KR100273482B1 - Multilayer Nonwoven Composite Web - Google Patents

Abstract

A first layer and a second layer of cellulose-based fibers, preferably cotton fibers, selected from the group consisting of meltblown thermoplastic artificial fibers, spunbonded thermoplastic artificial fibers, thermoplastic artificial staple fibers and composites thereof The second layer and the second layer are thermally bonded together at about 5 to about 75% of the surface area of the web to form a composite web having air permeability of about 25 to 37 fts / min / ft2, with improved liquid wick and retention Multilayered nonwoven composite webs having properties and particularly useful as a substitute for woven webs, such as textile webs. In a preferred embodiment, the composite web comprises at least one third layer of meltblown thermoplastic artificial fibers with a cellulosic fibrous layer interposed between the thermoplastic artificial fiber layers.

Description

Multilayer Nonwoven Composite Web

The present invention relates to a novel fibrous web, and more particularly to a novel multilayer nonwoven composite web in which a cellulosic fibrous layer and at least one thermoplastic nonwoven web are composited.

Nonwoven webs (fabrics) are defined as "sheets or web structures made by adhering and / or interlacing fibers, yarns or filaments by mechanical, thermal, chemical or solvent means". These webs do not need to convert fibers into yarns. Nonwoven webs are also referred to as so-called bonded webs or machined webs, and are called "nonwovens" because they are made by methods other than spinning, weaving or knitting. The basic structure of all nonwovens is a web of fibers or filaments. A single form of fiber or filament may be the basis of a nonwoven. Fibers measured in centimeters or inches, or fragments thereof, are called staple fibers. Generally, filament fibers are measured in kilometers or miles. In fact, filament fibers cannot be easily measured because their length spans several yards. For the fiber, the length must be significantly larger than the diameter. For example, the ratio of length-to-width (diameter) is at least 100 and usually much greater than this. Cotton fibers may be less than ½ inches to 2 inches or more in length and a typical length-to-diameter ratio may be about 1400. Other natural fibers exhibit the following typical ratios: flax fiber-1200; Ramie fiber-3000; And wool fibers-3000. As used herein, the term "fiber" is understood to include both short and long fibers, ie staple fibers and filament fibers, unless the fibers are specified as staples or filaments. For example, spunbonded webs consist of filament fibers, while meltblown webs include the fiber length of each bath such that these webs typically include both staple length and filament length fibers. In nonwovens, each individual fiber may be in a systematic or irregular arrangement. Tensile properties, stretching properties and tactile properties are imparted to the web not only by the form of adhesion, but also by the fiber-to-fiber combability and reinforcement by its components. Techniques for making nonwoven webs are based on the following key elements: fibers of various lengths and diameters; A web arranged according to the method of forming and processing; Bonding of fibers in the web and reinforcement by their components. By varying the combination of one or several elements within the composite, a wide range of nonwoven fiber types can be formed. Adjusting the shape and length of the fibers and adjusting the joints, along with the choice of manufacturing method, can provide a combination of highly technical and extremely flexible options. To date, nonwoven webs are a disposable substitute for prior art reusable test cotton gowns, surgical gowns, surgical drapes, face masks, shoe covers, sterile wraps, and other products. It is known to be used in the medical industry, estimated to exceed $ 1 billion. It is also known that nonwoven webs can be used in hygiene products such as sanitary napkins, disposable diapers, incontinence pads, and other similar products. To date, one of the advantages of nonwoven webs is that they are relatively low in cost compared to woven webs. The difference in cost between the nonwoven web and the woven web has been such that a real user can dispose of the nonwoven web product after one use and realize financial benefits over the multipurpose woven web.

Among the desirable properties desired for nonwoven webs used for medical and hygienic purposes are the feel (flexibility and drape), wicking, liquid retention, liquid absorption, and strength of the web. In addition, an important point in the acceptance of the nonwoven web by the real user is the extent to which the nonwoven web can approach the desirable properties of woven webs, especially cotton webs. Nonwoven webs generally have the disadvantage that many of the properties of woven webs are particularly poor in touch, wicking and liquid absorbency and liquid retention. Meltblown nonwoven webs exhibit pore volumes of, for example, about 85%, and spin-bonded nonwoven webs exhibit empty volumes of 90-95%. These webs also often exhibit undesirable chemical properties, such as hydrophobicity, which makes them less desirable, for example, for medical use. Moreover, the surface properties of these nonwoven webs are flexible and therefore tend to exhibit a smooth or oily feel and appearance. Since the fibrous materials of conventional nonwoven webs have in common a low surface tension, aqueous liquids are not attracted to the fibrous materials, and therefore these prior art webs have poor wicking and retention of these liquids. These webs are also difficult to treat with liquid repellents. In addition, the filamentary properties of the fibers of most prior art webs and methods of making them allow the fibers to be positioned in the web with the length dimension of the fibers arranged substantially parallel to the plane of the web, thus absorbing liquid into the body of the web. This is bad. To date, extensive efforts have been made to improve the properties of these nonwoven webs, including variations on how to manufacture and / or process the webs. However, these efforts increase the cost of the nonwoven web and can adversely change the monetary benefits over the woven web. In addition, since the fibers of the nonwoven web are usually petroleum-based, the market price of these raw materials has fluctuated significantly, and it has been important to finally treat the product after use.

The present invention provides a novel multi-layer composite web in which all layers are nonwoven and can exhibit the desirable properties of woven webs and the economic advantages of nonwoven webs. The web of the present invention is multilayered and is selected from the group consisting of melt blown thermoplastic artificial fibers, spunbonded thermoplastic artificial fibers, thermoplastic artificial staple fibers and combinations thereof, and having a weight of about 0.05 to about 10 oz. / yd ² lightweight first layer of man-made fibrous material; And a second layer of cellulosic staple fibers (excluding wood fibers) having a weight of about 0.1 to about 10 oz / yd ² , a fiber length of about 0.5 to about 3.0 inches, and a fineness of about 3 to 5 μm. These layers are bonded together by heat to form a composite web, and the adhesion area between the layers is preferably about 5 to about 75% of the area of one of the flat surfaces of the composite web. The bonding mode presented in this invention is in a form that does not adversely affect the web's tactile properties and other physical properties of the web, such as liquid wicking rate and retention rate. Thus, the preferred adhesion is only from one side of the laminate. In a preferred embodiment, the composite web comprises at least one third layer of fibrous material selected from the group consisting of meltblown thermoplastic artificial fibers, spunbonded thermoplastic artificial fibers, thermoplastic artificial staple fibers and combinations thereof. . This third layer is also lightweight and weighs about 0.05 to 10 oz / yd ² and is disposed on the face of the second layer opposite the first layer and thermally bonded to at least the second layer so that the second layer is the first layer. It is preferred to be inserted between the layer and the third layer. Other additional similar layers of similar material may be included in this composite.

The composite web product of the present invention, regardless of the number of layers used in the manufactured product, has a weight of about 0.5 to about 24 oz / yd ^{2 so} that the feel, drape and other properties are similar to the woven web. It is preferable to indicate. These limitations on the web of the present invention make it desirable, such as strength properties, wicking properties, liquid absorption and retention properties, and barrier properties (the ability to remove liquid while allowing or facilitating the movement of vapor and gas through the thickness of the web). It is necessary to carefully select the weight of each of the individual layers of the composite web that can provide the necessary or other necessary properties.

The composite web of the present invention is particularly useful for the manufacture of disposable medical products because of its excellent barrier properties, tactile feel, breathability, strength, wicking, liquid absorbency and liquid retention.

Referring to the drawings attached herein,

1 is a schematic diagram showing one embodiment of a web having various features of the invention;

2 is a schematic diagram showing another embodiment of a web having various characteristics of the present invention;

3 is a schematic view showing a manufacturing process of a web having various characteristics of the present invention;

4 is a schematic diagram showing a further process for producing a web having various properties of the present invention;

5 is a schematic diagram showing an additional process of making a web and showing an in-line web-forming apparatus;

6 shows an apparatus for use in testing liquid absorption and retention of webs;

7 shows an apparatus used to test the wick characteristics of a web;

8 to 34 are graphs showing wick values of samples classified in Table X;

FIG. 35 is a graph showing the wicking response of a lysate according to the present invention having various face core weights;

36 is a graph showing the wicking reaction of unlaminated cotton webs;

37 is a graph comparing laminates with cotton cores and laminates with ramie cores for wicking reactions.

In FIG. 1, the composite web 10 shown includes a first layer 12 and a second layer 14. These layers are bonded to each other and spaced apart from each other as shown by diamond-shaped bonding patterns 16 of approximately the same size as shown. These adhesive sites preferably extend over almost the entire area of the composite web to serve to integrate the layers into the composite web. FIG. 2 shows an additional web 10 ′ comprising a similar first layer 12 ′ and second layer 14 ′, each further including a third layer 20.

At least one of the layers of the composite web of the present invention is made of thermoplastic man-made fibres. Thus, the mutual bonding of the webs is such that various well-known thermal bonding means, such as passing the laminated layers through a set of heated rolls. It may be performed by any of the above. At least one of these rolls has a surface pattern of the protrusions 30 (see FIG. 3), which pattern is applied to the composite web by the rolls when the composite web is injected through a nip between these rolls. The combination of the pressure and the inverse provided creates a spaced adhesion site, such as the diamond-shaped site shown in FIG. Other thermal coupling means, such as ultrasonic welding, may be used if desired. Other techniques for bonding the impacts of composite webs of the present invention may include physical entanglement of multiple layers of fibers, such as by hydration, needle puncture, and the like. In any case, the desired bonding between the collisions is by means of relatively small spaces of adhesion, spaced apart, which extends over almost all of the composite web to form a single layer of adhesive web without adversely affecting the properties of the desired web. Effectively develop from In the adhesive action, about 5 to about 75% of the surface portion of the composite web constitutes an adhesive portion between the layers of the web. However, it is preferable that the total percentage of adhesive portions of the composite web is about 10 to about 25% of the area of the composite web.

In one embodiment of the method of making the composite web of the present invention, it is preferred that the layers of the web are each formed separately and laminated in a laminating-type operation. When the layers are kept in the condition of lamination, the web is bonded as described above. However, several layers of the web of the present invention may be formed at about the same time as in an in-line production process, wherein if one of the two layers is formed, a second or additional layer is formed on the first or previously formed layer. do. In this latter example, the gluing action may also be in-line and may be in a downstream position for the formation of the final layer of the web. These manufacturing techniques are well known to those skilled in the web manufacturing art. 3 shows a layer of previously formed layers 15, 17, 19 on a conveyor 21 moving forward to a web, and then the web is nipped 24 of a set of heated rolls 26 and 28. A method of bonding the layers to the composite web 21 by passing through is shown schematically. In this embodiment, the upper roll 28 is provided with a pattern of surface protrusions 30 which promotes the formation of the desired spaced adhesive portions 16. The composite web is withdrawn to roll 32 for storage and subsequent use, as shown. If necessary, the webs 15 and 19 are each molded from an artificial fiber that provides a composite self-sustainable web, for example by spunbonding, meltblowing or other methods.

4, the first layer 40 of thermoplastic synthetic fibers is formed using a conventional melt blowing or spunbonding method 44 and then deposited on a conveyor 42 moving forward to form a web of the present invention. The method of preparation is shown schematically. As described in FIG. 5, a layer 48 of cellulosic fibers produced offline or inline is added onto a first layer 40 disposed on a moving conveyor 42. The third layer 50 of thermoplastic man-made fibers is formed by conventional melt blown or spunbonding methods 51, which are laminated onto a cellulosic layer 48 to provide a web of three layers, in which the web The cellulosic fibrous layer 48 is disposed between the outer layers 40 and 50 of the thermoplastic artificial fibrous material. In the method shown, these multiple laminated layers are injected through a set of heated press rolls 54 and 56 to thermally bond the multiple layers to the composite web 59, wherein the pressure rolls One of them has a pattern of protrusions 58 on its outer surface. The composite web can be returned to roll 60 for further use. As will be described more fully hereinafter, one or both of the first layer 40 and the second layer 50 may be subjected to conventional meltblowing, spunbonding or similar techniques, including thermal bonding of artificial staple fiber webs. It can be formed by.

With respect to FIG. 5, a further embodiment of the method of manufacturing the web according to the invention is shown. In the method shown, for example, the first web 64 of man-made fibers is formed as by an on-line conventional meltblown or spunbonding device 66, which is injected past an idle roller 65. And is deposited in an upper run of the first conveyor 67. The method also includes a bale 69 of cellulosic fibrous material introduced into the inline carding unit 70 from the inline carding junction 68 as shown, and the carded web 71 being the second conveyor. Inline carding joint 68 is injected directly from carding unit on 72. From the conveyor 72, the cellulosic web is injected forward onto the top of the web 64 on the conveyor 67. In addition, a third web 74 of artificial fibers is formed as by an additional inline conventional meltblown or spunbonding apparatus 75, which is injected past the flow roller 76, The cellulosic layer 71 is laminated on the upper surface of the cellulosic web 71 inserted between the web 64 and the web 74 of artificial fibers. These web layers are injected forward through the heated rolls 78 and nips 77 of the set of rolls 79, the upper rolls 78 of these heated rolls having an upper web 74 and a cellulosic web 71 A projection 81 is provided on the outer cylindrical surface of the roll, which performs a thermally spaced gap between the molds to form this impact into a composite web. The bonded composite 83 is withdrawn to roll 85 for later storage and use. Optionally, the layer of artificial staple fibers is molded into a web 87, such as by conventional airborne web forming apparatus 89, to form cellulosic webs 71 and artificial fiber webs 64 and 74. It can be inserted between one or both to be a composite 83.

In the present invention, the composite web includes at least two layers. In any case, one or more of these layers are molded from cellulosic fibers. As used herein, "cellulosic" is meant to include staple fibers comprised of about 25% to 100% of cellulosic material. Suitable cellulosic materials from which fibers can be obtained include cotton, ramie, hemp, jute, flax, kenaf, sugar cane, eucalyptus, rayon (regenerated cellulose) and combinations thereof, but include wood fibers I never do that. Selected cellulosic fibers are typically processed as is well known in the art to obtain clean, clear fibers that readily absorb liquids. For example, refining and bleaching cotton removes oil and the like from the fibers, making the fibers flexible and absorbent, as well as the cleanliness and color clarity (white is regarded as one color) of foreign materials. Partially refined with little or no bleaching, however, can in most cases exhibit sufficient absorbent and / or wicking properties in use. Cellulose fibers suitable for use in the web of the present invention are about 0.5 to about 3 inches in length. Cotton fibers are preferably in the range of 0.5 to 1.25 inches long, while ramie or flax fibers are preferably in the range of 0.5 to 1.25 inches, while ramie or flax fibers may be in the range of about 3 inches or less in length. If necessary, the longer fibers can be cut into shorter fibers. The cellulosic fibers used are not molded into yarns. However, the fibers can be processed, such as by carding or similar, to align these fibers, or to irregularize these arrangements, and to shape the fibers into a self-maintaining web. If desired, the fibers can be used directly from a bale obtained from a fiber processing operation, in which case the fibers can be introduced as a layer into the web of the invention, in which the fibers are carded so that they are somewhat parallel to each other. Or irregularly arranged. It is preferred that the cotton fibers have a fineness of about 3 to 5 microns so as to be flexible enough to express the desired hand and drape among other properties of the composite web of the present invention. Cotton fibers of about 5 μm or more in size are less flexible, from which the shaped webs tend to be rough and unacceptable to the touch. Cotton fibers are a preferred type of cellulosic fibers used in the composite web of the present invention. Cotton fibers have a smooth surface and exhibit surface energies of about 44 dyne / cm compared to the surface energy of about 31 dyne / cm of polyolefin fibers, so that they remain in place in a layered state in the composite web of the present invention. It shows a tendency. Cotton fibers also contribute to wicking properties, absorbency, liquid retention, bulkiness, liquid repellency, vapor and gas permeability for composite webs, and are lighter than 0.5 oz / yd ² (17 g / m ² ), especially for certain composite structures. When meltblown webs are used, they impart significant properties such as strength.

Regardless of which of the cellulosic fibers is used to fabricate the inner layer of the multilayer composite web of the present invention, the inner layer should consist of staple length fibers opposite to the filament length fibers. Staple fibers are relatively short in individual lengths, most often a mixture of lengths of about 3 inches or less, preferably less than about 2 inches, to provide multiple ends to the fibers. These fibers are not formed into yarns, but it is desirable that the fibers not have any other major configuration other than the fact that these fibers are formed into a web that is sufficient to be laminated on a conveyor or manipulated by an automatic device for laminating onto an additional web on the conveyor. As long as the fibers are present in the inner layer, the fiber ends tend to extend in all directions within the web. Thus, many fiber ends may protrude from the flat central surface of the web. This feature of the staple fiber web is one of the main reasons that can be used in medical applications. According to the present invention, a web which could not be used so far is trapped between two webs of artificial nonwoven fibers so that the artificial web serves to receive short cellulose fibers. However, these artificial fiber webs must be carefully selected so as not to adversely affect the desired tactile properties of the resulting composite web. Also important is that the man-made fiber web should be chosen for its ability to impart the desired tactile and liquid wicking and retention properties to the composite web. It is formed into a web by the process of forming a substantial pore volume in the web in the present invention, wherein the web is formed of cellulose fibers such that vapor or liquid passes through the thickness of the web so that the liquid is quickly captured and does not pass through the composite web. This is achieved by using a web of artificial fibers made of fibers of finer fineness that do not inhibit migration into the inner layer but at the same time provide a barrier to bacteria and the like.

The short staple fiber ends of the inner layer of the composite web, which are generally lateral to the plane of the inner layer, serve to define many areas of liquid transport into the inner layer. Specifically, the outer layer of artificial fibers is naturally hydrophobic and has a low surface tension value. These fibers are also continuous in length and are poor transporters of liquids. On the one hand, the staple fibers of the inner layer are hydrophilic and have relatively high surface tension values, which are not smooth and are crushed along their length and are present in large numbers to attract their liquid into the body of the inner layer. In addition, many ends of the staple fibers of the inner layer extending laterally with respect to the plane of the inner layer have their affinity for the liquid and their large number in the inner layer, their geometric position and physical position moving the liquid into the inner layer. The path of transport of the liquid to the inner layer is defined by the fact that it defines a number of capillaries in the inner layer that strengthens and assists the retention of liquid in the inner layer. Cotton fibers are also preferred in webs because they expand when the web is wet if the web is expected to absorb liquids and act as a barrier.

As is widely recognized in the prior art, webs of cellulosic fibers in which the fibers are not bonded to each other cannot be used in most disposable medical supplies. First, the web does not have sufficient strength to exhibit self-maintenance, and second, the fiber can be an unacceptable source of misunderstanding because it is free from the web. For example, loose fibers of a surgical gown that enters an exposed wound or incision can be a source of granulomas in a patient, so the fibers must be appropriately contained in the present invention. According to the invention, the cellulosic fibers are mixed with the thermoplastic artificial fiber layer. The mixing of the cellulose-based fibrous layer and the thermoplastic artificial fibrous layer provides a composite composite web that exhibits increased properties, in particular wicking, liquid retention and strength, when these layers are spaced apart and thermally bonded to one another. In particular, the layer of artificial fibers provides abrasion resistance and strength to the composite web, so that in a preferred composite web a cellulosic fibrous layer is inserted between the outer layers of the artificial fiber.

While meltblown and spunbonded webs of conventional thermoplastic artificial fibers have been formed, additional special treatment is required to make these webs useful for disposable medical and hygiene articles, while the inventors have selected cellulosic layers selected from those webs. It has been found that the joining in one bonded composite web can produce a composite web that can incorporate these specific webs directly into the composite web of the present invention without the need for special treatment of the man-made fiber web. This performance provides a substantial economic advantage for the present invention.

In the present invention, the artificial fiber web is preferably formed by meltblowing or spunbond techniques. The meltblown fibers of these artificial fibers preferably have a diameter of about 0.5 to about 20 μm, whereas the diameter of the fibers in the spunbonded web is laminated to the meltblown web at a low end of about 0.8 μm, overlapping and less than 50 μm. Or above the top end of these diameter ranges. Spunbonded webs are generally harder than meltblown webs because they typically receive significant positions after quenching. In both cases, the fibers are formed into self-sustaining webs. Preferred weights of meltblown webs for use in the present invention are light weights ranging from about 0.05 to about 10 oz / yd ² , most preferably from about 0.25 to about 2 oz / yd ² . Preferred weights of the spunbonded webs for use in the present invention are also lightweight, in the range of about 0.1 to about 10 oz / yd ² , most preferably 0.3 to about 2 oz / yd ² . Webs lighter than about 0.05 oz / yd ² tend to have insufficient fiber density to contain cellulose fibers and provide the strength and other properties required for composite webs. Heavy weight webs, ie, webs of about 10 oz / yd ² or more, tend to form undesirably coarse composite webs when mixed with the cellulose fiber layer. A detailed description of the spunbond and meltblown processes and the web produced thereby is described in "Proceedings, Fiber Producer Conference 1983", April 12, 13 & 14, 1983, pp. Publications titled 6-1 to 6-11, the contents of which are incorporated herein by reference.

Preferred composite webs according to the present invention comprise an inner layer of cellulosic fibers sandwiched between outer layers of artificial fibers. Thus, composite webs may include different combinations of layers. For example, in addition to the required layer of cellulosic fibers, the composite web includes a first layer of meltblown artificial fibers in contact with one side of the cellulosic fibers and a third layer comprising spunbonded artificial fibers adjacent the opposite side of the cellulosic fiber layer. can do. Likewise, both the first and third layers can be meltblown fibers or spunbonded fibers. In addition, a multilayer of cellulose fibers may be provided that may or may not be separated by an additional inner layer of meltblown or spunbond artificial fibers. In some cases, the cellulose fibers are protected by at least one outer layer, preferably two outer layers of artificial fibers. It is well known that adding another layer to the composite web can increase the cost of the web and reduce the feel or other characteristics of the composite web.

Samples of composite webs using the features of the present invention were prepared according to the process illustrated in FIG. In preparing the sample, the cellulosic fibers are fed to an opener-mixer where the fibers are opened from the bales and mixed uniformly. The fibers from the opener-mixer are fed through a card, where the fibers are carded to form a web, which is fed onto a layer of thermoplastic artificial fibers doped directly from the card and wound on a conveyor. The card used in the preparation of this sample has a randomaizing unit attached to its discharge end, whereby the fibers were randomly placed on the web without the desired arrangement in the machine direction. Then, a third layer comprising thermoplastic artificial fibers is laminated on top of the cellulose fiber layer so that the cellulose fiber layer is inserted between the two outer layers of thermoplastic artificial fibers. This laminate was then fed through the nip between the heated roll sets. One of the rolls has a smooth surface, the other roll is provided with a protrusion pattern at a distance, and each protrusion has a diamond pattern cross section. Tables I and II provide details regarding the operating parameters used in the preparation of these samples and the composition of the various samples.

Samples generated as listed in Tables I and II were tested for various properties as described below:

block. Blocking refers to the ability of the fabric to suppress the permeation of liquids and microorganisms. The barrier property protects nurses and patients in the operating room from infection.

Exam Procedure

Water resistance AATCC test method 127-1985

Oil repellency grade AATCC test method 118-1983

Waterborne Permeability AATCC Test Method 42-1985

Water spray grade AATCC test method 22-1985

burglar. Medical nonwovens must also be strong enough to prevent tearing and puncture all the way from the manufacturing stage to the use of the workpiece.

Exam Procedure

Fracture Load IST ¹ 110.0-70 (82)

Elmendorf Tear Strength IST 100.0-70 (R82)

Mullen Bursting Strength IST 30.0-70 (R82)

Tensile Strength IST 110.0-70 (82)

※ Drape and comfort. The drape of nonwovens means the ability to match the shape of the object covered by this fabric. Subjects include patients, operating tables and equipment. Comfort is about breathability, the choice of materials and the design of the product.

¹ INDA (Association of the Nonwoven Fabrics Industry) standard test.

Exam Procedure

Frazier Air Permeability TST 70.1-70 (R82)

Cantilever Bending Length ASTMD 1388-64

The results of these tests are reported in Tables IIIA and IIIB.

The data in Table III show the strength values of the inventive laminates that are fully suitable for the expected use of the inventive laminates as a substitute for synthetic fibers or filaments, i.e., conventional textiles formed only from conventional SMS fabrics used to date for medical use. To indicate In addition, the laminates of the present invention exhibit good hand (bending length) and liquid barrier properties compared to laminates that do not include a layer of cellulose fibers. Laminates of the present invention possess excellent properties related to liquid absorption, retention and wicking, which ensure that they can be used even more usefully and preferably for medical use.

[Repellent Processing]

The laminated samples were processed with fluorine chemicals to improve their liquid repellent properties (water, oil, blood, alcohol and other aqueous liquids) and the barrier properties of the fabric.

The fluorine chemical processing was performed on the laminate samples using the padding technique, which is a common method of applying continuous processing. In this technique, the sample was immersed in a chemical mixture and then passed through the nip of a set of rollers to squeeze out excess chemical from the laminate saturated by the nip pressure. The nip pressure is adjusted to achieve the desired moisture pickup rate (WPU%). The moisture pickup rate is the amount of processing liquid absorbed by the laminate sample. The amount of raw sample was cut and quenched. Samples passed through padding rollers for processing fluorine chemicals were removed after processing. Moisture pickup rate was determined by the following equation;

WPU% = (weight of processed sample-weight of raw sample) / weight of processed sample x 100

Moisture pickup rates of the different laminate samples are reported in Table IV.

Fluorine compound treatment was performed using an 18 inch wide padding mangle. The fluorine chemical used to process the laminate samples was DuPont's 5% "jonyl" PPR fabric protector. A moisture pickup rate of 140% was set. Samples were subjected to fluorine chemical processing in two dips and two nippa padded mangles at a pressure of 30 psi. The processed samples were then dried at 250 ° F. for 3.5 minutes on the pan frame of the convection oven. The following fluorine chemical formulations were used:

Padding application technology (140% moisture pickup rate)

Component weight%

Zonyl PPR 3.6

Water 96.4

Total amount 100.0

Fluorine chemically processed samples were tested for barrier, strength and water resistance and comfort using the test procedure described above. The results for the processed laminate samples are reported in Table V.

The water resistance level required to pass the liquid through the sample was markedly higher in the raw sample, which demonstrated good barrier properties provided by the meltblown web. However, the liquid-repellent processed samples 1, 2 and 3 containing only cotton staple fibers in the middle layer showed much more water resistance levels than the corresponding unprocessed samples, and the processed samples with only polypropylene (PP) in the middle. In general, higher levels of water resistance were found. On the other hand, the water resistance of most samples having only polypropylene in the center was significantly reduced by the liquid repellent processing. The water fraction grade of most processed samples has been shown to increase as a result of fluorine chemical processing. The biggest advantage of fluorine chemical processing was that the oil repellency rating increased to 0.0 (raw sample). In addition, fluorine chemical processed samples containing only cotton in the center consistently showed high oil repellency values of 8.

Samples 8-15 in the following table were used for comparison. Except for Sontara fabrics containing wood pulp, none of the samples contained a cellulosic fibrous layer, but contained at least one layer of artificial fibers. Table VI provides the composition and preparation method for each sample.

These samples were tested for several properties considered to be important in laminates used as replacements for woven webs. The results of these experiments are reported in Table VIII.

For further comparison, several woven fabrics were purchased that differ in fiber content, weight, and processing type and are described in Figure VII. 100% cotton denim fabric is often used as a pants material. Poplin fabrics are often used in pants and shirts. Denim fabrics are used at nominal weights of 10, 12 and 14.5 oz / yd ² . "Indigo" denim consists of such nonwoven fabrics (undelogging), stripped and weakly refined fabrics, and stripped, weakly refined and fluorine chemical processed fabrics. It became. Some of the "white" denim fabrics were also processed with fluorine chemicals. Poplin fabrics were evaluated after de-lamination, scouring and bleaching DP processing and after combination of DP processing and fluorine chemical processing. All pretreatment, DP processing and liquid repellent processing were performed using commercially available equipment. Further analysis of these fabrics is reported in Table VIII. The test results performed on the fabrics are reported in Table VIII.

The composite web of the present invention exhibited a tactile feel and drape close to the type of woven webs that have been used in surgical gowns and similar medical supplies to date. The air permeability of the composite web of the present invention, ie, about 25 to about 37 ft ³ / min / ft ^2, is comparable to that of woven webs such as shirt materials and thus provides equivalent barrier properties and breathability as such woven webs. The presence of the fibrous layer in the composite web according to the present invention provides enhanced permeability compared to conventional single layered woven webs, thereby increasing the usefulness of the composite web to applications where the barrier properties of the web are important.

The absorbency and retention of laminates, cotton mats and conventional fabrics prepared according to the invention were examined. Absorption capacity was measured by melting the procedure developed by the Swedish Textile Institute (TEFO) and reported by the TAPPI Journal, July 1987. 6 shows a test apparatus consisting of a large funnel 80 to which glass frit 82 is attached and a graduated collection cylinder 84. Circular test pieces 86 having an area of 100 cm ² were placed overnight at 21 ° C. and 65% RH. The sample was placed on top of the glass frit. The test piece was saturated with 100 ml of liquid delivered at a rate of 7 mm / sec from a height of 2.54 cm. 100 gm of 100 cm ² round weight (88) was quickly placed on a saturated test piece and the composite was drained for 10 minutes. The amount of liquid collected in the cylinder was measured and the product's absorption capacity (C) was calculated by the following formula: C = a-b

Where a is the total liquid volume (100 ml) and b is the liquid (ml) not absorbed under 100 Pa pressure.

Each test sheet was repeated seven times.

This result is reported as a millimeter approximation. Retention capacity was measured as a series of absorption capacity measurements. After measuring the amount of unabsorbed liquid at 10 minutes in the performance test, a weight of 2.9 kg was loaded on top of the sample for a pressure of 3 kPa (a load of 100 Pa was already hung on the test piece from the performance test). The complex was drained for 5 minutes. At the end of this period, the amount of liquid in the cylinder was noted, and an additional 2 kg weight was applied even though a total load of 5 kPa was applied. The wet sample was allowed to stand for another 5 minutes before measuring the amount of liquid collected in the cylinder. The amount of liquid (C _rm and C ' _rm ) in which the sample was retained under two different pressures was calculated as follows: C _rm = C-c, where C is the absorbing capacity and c is the unabsorbed liquid under 3 kPa pressure. ); C ' _rm = C-c', where C is absorbent and c 'is an unabsorbed liquid under 5 kPa pressure.

This test was repeated seven times for each sheet and the results are shown in milliliter approximations. The results of these tests are reported in Table XI. For another comparison, the absorption and retention of 100% carded cotton webs under various loads are reported in Table XII. Samples 37-40 of Table XI do not contain a cellulose fiber layer. In particular, their absorption and retention capacity is negligible. From these data and the data in the above table, it is evident that the laminates of the present invention are superior in many physical respects, in particular for medical use, to conventional nonwoven fabrics. It is also noted that the fabrics of the present invention are light weight and are actually superior in terms of the fabric liquid absorption and retention capacity of the present invention having a smaller amount (weight) of meltblown material. Thus, the fabric of the present invention provides economic advantages. Moreover, although 100% cotton appears to lose some capacity as the web increases in weight, when these cotton webs are incorporated into the laminate structure of the present invention, the laminate product unexpectedly increases the weight of the cotton into the inner layer. Improved retention.

The wick of the sample was tested using the apparatus facility shown in FIG. The device is equipped with a top loading balance (90) with a printer (92), a laboratory jack (94), a water reservoir (95) holding a test liquid (96), and a thick (40-6Oμ) glass frit (100). Funnel 98, rubber tube 102 connecting funnel 98 to water reservoir 94, 100 g circular weight (area 100 cm ² ), and stop position (not shown). The funnel 98 is mounted on the ring stand 110 in a vertically adjustable manner. A 100 cm ² round sample 108 is randomly cut from the sheet left overnight at 20 ° C. and 65% relative humidity. Seven samples are cut from each test sheet. Procedurally, raise the test liquid reservoir until the surface of the glass frit is condensed (but not with water). Place the specimen on the frit at 100 g circular top weight. Operate the stop position while setting the weight of the sample and read the weight of the test liquid lost from the reservoir into the sample every 10 seconds over 3 minutes. This provides enough time for the amount of liquid to be absorbed into the sample to be stable. This result is represented by a curve of time versus amount. This procedure was repeated seven times for each sheet to be evaluated. The results of the analysis of several samples are reported in Table X. Curves of time versus amount of results obtained from the testing of these samples are presented in FIGS.

Of particular note in FIGS. 8 to 34 is that the wicking characteristics of conventional laminates containing man-made fibers or filaments appeared very poor. On the other hand, the fabrics produced when these fabrics are laminated with a layer of natural cellulose fibers exhibit excellent wicking properties, thus providing fabrics suitable for medical and other applications.

While the present invention has been described with reference to specific embodiments, those skilled in the art will recognize that various modifications can be made within the scope of the present invention. For example, other bonding patterns may be used in addition to the diamond patterns described herein. In addition, various fluorine compound processing agents are commercially available and are well known in the art. See, eg, Menacombe Lewin and Stephenme. Handbook of Fiber Science and Technology edited by Sello: Volume II. Chemical Processing of Fibers and Fabrics, Functional Finishes, Part B]. The contents of this document, especially the pages 172-183, are incorporated by reference herein.

Claims (23)

A multi-layer nonwoven composite web useful for use as a substrate for woven webs, the method comprising from 0.05 to 10 selected from the group consisting of meltblown thermoplastic manually processed fibers, spunbonded thermoplastic manually processed fibers, manually processed thermoplastic staple fibers, and combinations thereof oz / yd ² weight first fibrous material layer; A second layer of staple fiber nonwoven fabric based on cellulose, having a weight of 0.1 to 10 oz / yd ² , a length of 0.5 to 3 inches of fiber and a fineness of 2 to 5 microns of fiber; And a fibrous material selected from the group consisting of meltblown thermoplastic manually processed fibers, spunbonded thermoplastic manually processed fibers, manually processed thermoplastic staple fibers, and combinations thereof. Consisting of a third layer of 0.05 to 10 oz / yd ² weight disposed on the opposite side, wherein the first layer, the second layer and the third layer are sandwiched between the first layer and the third layer. The web is disposed in a lying direction on the web surface so as to intervene and non-hydraulically bonded to each other, wherein the first layer and the second layer are non-hydraulically bonded to each other so that the air permeability is 25 to 37 ft ³ / min / ft ² Wherein the bonding area between the layers is between 5 and 75% of one of the areas of the composite web. The fiber material of claim 1 wherein the third layer is comprised of a fibrous material selected from the group consisting of meltblown thermoplastic passive processed fibers, spunbonded thermoplastic passive processed fibers, manually processed thermoplastic staple fibers, and combinations thereof. 0.05-10 oz / yd ² , bonded to the second layer such that the second layer can be interposed between the first layer and the third layer so as to be disposed opposite the first layer relative to the second layer Multilayered nonwoven composite web, characterized in that. The multi-layered nonwoven composite web of claim 1, wherein the layers are thermally bonded to one another at regular spatial intervals over a flat area of the web. The multilayer nonwoven composite web of claim 1 wherein the pore volume of the first and third layers is at least 85%. The multi-layered nonwoven composite web of claim 1, wherein the composite web has a moisture wicking rate of 0.01 g / sec to 0.05 g / sec and a water retention value of 7 to 15 ml at 3 kPA. The multi-layered nonwoven composite web of claim 1, wherein the burst strength of the composite web is 40 to 225 kPA. The multi-layered nonwoven composite web of claim 1, wherein the bond is thermally bonded at spaced apart bond areas. The multi-layered nonwoven composite web of claim 1, wherein the ends of the fibers extend outwardly from the side of the second layer plane to the first and third layers and through the layers. The multi-layered nonwoven composite web of claim 1, wherein the fibers of the second layer are cotton fibers having a length of 0.5 to 1.25 inches and a fineness of 3 to 5 microns. The multi-layered nonwoven composite web of claim 1, wherein the bonding area between the layers is 10-30% of the composite web area. The multilayer nonwoven composite web of claim 1, wherein said first layer is a meltblown web. The multi-layered nonwoven composite web of claim 1, wherein said first layer is a spunbonded web. 2. The multi-layered nonwoven composite web of claim 1, wherein said first and third layers are meltblown webs. The multi-layered nonwoven composite web of claim 1, wherein the first and third layers are spunbonded webs. The multi-layered nonwoven composite web of claim 1, wherein the first layer is in the form of a meltblown web and the third layer is a spunbonded web. The multi-layered nonwoven composite web of claim 1, wherein the thermoplastic artificial fibers are polypropylene fibers. The multi-layered nonwoven composite web of claim 1, wherein the staple fibers of the second layer are comprised of 25 to 100% cellulose material. 17. The multilayer nonwoven composite web of claim 16, wherein said cellulose material is a cotton material. The multi-layered nonwoven composite web of claim 1, wherein the fibers of the second layer are buckled along its length. A multi-layer nonwoven composite web that can be used as a substrate for a woven fabric web, wherein 0.05-10 oz / yd is selected from the group consisting of melt blown thermoplastic artificial fibers, spunbonded thermoplastic artificial fibers, thermoplastic staple artificial fibers, and combinations thereof A first layer of ^two weights of fiber material; And a second layer of staple fiber nonwoven fabric based on cellulose not derived from wood and having a weight of 0.1 to 10 oz / yd ² and a length of 0.5 to 3 inches and a fineness of 2 to 5 microns. The first layer and the second layer are non-hydraulically bonded onto the web surface such that the air permeability is 25 to 37 ft ³ / min / ft ² and the weight is 0.5 to 24 oz / yd ² and the bonding area between the layers is A multi-layer nonwoven composite web, characterized in that it forms an adhesive web that is 5 to 75% of the area of the composite web. 20. The multilayer nonwoven composite web of claim 1 or 19, wherein the first layer has a weight of 0.25 to 2.0 oz / yd ² . 20. The multilayer nonwoven composite web of claim 1 or 19, wherein the second layer has a weight of 1-4 oz / yd ² . 20. The multi-layered nonwoven composite web of claim 1 or 19, wherein the bonding area between the layers is 10-30% of the area of the composite web.