JP2005515912A - Filled nonwoven laminate with barrier properties - Google Patents

Abstract

  The present invention is directed to a single use, disposable absorbent laminate (10) comprising one or more layers (12), (22) of a hydrophilic melt spun material bonded to a breathable film (14). Yes. The melt spun fabric layers (12), (22) may comprise at least one spunbonded fabric, meltblown fabric, or other nonwoven that has been rendered hydrophilic prior to bonding to the film (14). The filament or microfiber of the spunbonded or meltblown fabric may contain a hydrophilic additive in or on the filament or microfiber. The surgical drape film (14) remains breathable while the laminate can resist the penetration by liquids and viruses.

Description

  The present invention is directed to a single use disposable absorbent laminate comprising a nonwoven web bonded to a breathable film. Such laminates include, but are not limited to, surgical and healthcare related products such as surgical drapes and gowns, disposable work clothing such as coveralls and laboratory clothing, and diapers, training pants, incontinence clothing, physiological It has a variety of uses in the field of limited use and disposable items, including personal care absorbent products such as napkins, bandages, wipes, etc. Many of these products require highly technical components and at the same time are required to be of limited use, i.e. disposable items. “Limited use or disposable” means that the product and / or component is used only a few times or once before being discarded.

For example, surgical drapes are designed to greatly reduce fluid permeation through surgical drapes if not prevented. In the surgical environment, these sources of fluid include patient bodily fluids such as blood, saliva, and sweat, and life support fluids such as plasma and saline. Previously, surgical drapes were made of cotton or linen. However, surgical drapes tailored from such materials are permeable or “run through” the various liquids encountered in surgical procedures. In such cases, there was a path through which biological contaminants present in or subsequently in contact with the liquid could permeate the surgical drape. Also, in many cases, surgical drapes made from cotton or linen have poor barrier properties against the permeation of airborne contaminants. In addition, such articles are expensive and, of course, require washing and sterilization steps before reuse.
Currently, disposable surgical drapes are widely replaced by linen surgical drapes. Advantages in such disposable surgical drapes include forming such articles from a liquid absorbent fabric and / or a liquid impervious film that prevents the liquid from penetrating. See, for example, Japanese Patent No. 8080318 assigned to Kyowa Hakko Kogyo Co., Ltd., US Pat. No. 5,546,960 assigned to Molnlycke AB, and WO 96/09165 assigned to Exxon. In this way, biological contaminants carried by the liquid are prevented from passing through such fabrics. However, in some situations, surgical drapes formed from absorbent fabrics and / or liquid-impermeable films are NFPA 702-1980 Class 1 flammability conditions, tear strength, and relatively “lint-free”. At the expense of other drape characteristics such as being free of fibrous elements of play. Class 1 flammability conditions are met when the material takes 20 seconds or more to spread 5 inches from a standardized ignition source according to NFPA 702-1980 test conditions.

In some cases, a surgical drape made solely from a liquid absorbent fabric, such as a fabric formed from hydrophilic fibers, absorbs liquid well and is more breathable than a non-porous material. However, the breathability provided by such nonwovens is usually at the expense of the drape's liquid barrier properties. Due to the desire for improved liquid absorbent and fluid impermeable barrier properties, absorbent nonwoven webs have been laminated to various films or barrier layers. One commonly available application of such a configuration is that it is used to form a surgical drape. A surgical drape marketed under the trade name Klindrape®, assigned to Mollyckie AB, is a liquid absorbent non-woven topsheet containing essentially hydrophilic rayon staple (discontinuous) fibers and a fluid non-woven topsheet. It is considered that it contains a permeable polyethylene intermediate sheet, a cellulose bottom sheet, and an adhesive component for attaching the top sheet and the bottom sheet to the polyethylene sheet. The above Klinidrape® has liquid absorbency and fluid impermeability, but the drape provides a relatively large number of lint particles with adhesive-type joints, meeting the class 1 flammability conditions of NFPA 702-1980. Do not pass.
In such drapes, the strength and fluid barrier properties are improved by laminating the nonwoven to the film. For considerations in surgical drape applications, spunbonded fabrics containing continuous synthetic filaments have been laminated to the film. Such laminate fabrics do not significantly increase the drape density and are relatively low cost. One such laminate fabric consisting of a multilayer film bonded to a support layer, such as a hydrophobic spunbonded fabric layer, is disclosed in British Patent No. 2296216, assigned to Kimberly Clark Worldwide, It is described as having a drape application. However, because the laminate spunbonded fabric component described above does not exhibit hydrophilic properties, drapes made from such laminate fabrics lack fluid absorbency.

Another laminate disclosed in WO 96/09165 and assigned to Exxon has a microporous film bonded between an outer nonwoven layer containing hydrophobic spunbonded filaments and a hydrophilic nonwoven inner layer. Composed of combined. For use as a surgical drape, the film component provides a barrier to fluid while the spunbonded component provides strength to the drape. However, this laminate uses an adhesive bond to attach the film to the nonwoven substrate.
Microporous films are well known in the art and in some embodiments typically consist of a film containing an amount of particulate filler material dispersed therein. These films having a particulate filler material are known as filled films. In typical processing conditions to form a filled microporous film, the particulate filler film is stretched and / or crushed between compression rollers, thereby creating pores in or around the particulates. This makes the film breathable and allows water vapor and other gases to permeate through the pores formed in and through the film in the area containing and near the pores, but not as water. Normally inhibits permeation of liquids. Filler-containing film treated in a manner to extend typically a breathable film having a moisture vapor transmission rate of at least 300 grams per square meter per 24 hours (300g / m ^2/24 hours).

  One approach to facilitating processing a filled film and subsequently laminating the film to other material components is to form a surface or “skin” layer on one or both sides of the filled film. is there. These additional film layers often have a low filler content, are monolithic film layers, or a combination thereof. Such multilayer filled films include a base or “core” layer containing pore-generating fillers, a skin layer optionally containing such pore-generating fillers or other fillers, and additives. Typically, the core layer provides most of the overall film strength and barrier properties, while the skin layer contributes to providing them but provides additional desired properties. The stretching and / or crushing processing conditions performed on these films can also make these films breathable. For multilayer filled films containing pore-forming fillers in all layers, stretching and / or crushing creates pores around the particles as described above, examples of such films are described in US Pat. No. 6,045,900. For multilayer filled films with or without a small amount or minimal pore-forming filler, film breathability can be obtained. This is due to the proper choice of polymer components, the contribution of inclusions in each skin, and the appropriateness of the multilayer film, for example to stretch the film so that the skin layer is thin enough to allow water vapor and other gases to pass through. Can be achieved by simple processing. McCorack et al. Describe examples of such films in US Pat. No. 6,075,179.

One problem in heat laminating the above material composition to another material composition has long been recognized and faced. The problem is that, as a result of known attempts to hot spot the nonwoven layer to the microporous thermoplastic film, the laminate often fails to meet the blood bleed-through conditions described in ASTM-F1670-95. It is. An example of this problem is given as a comparative example in US Pat. No. 6,238,767, where hot spot bonding is used to join a multilayer stretched thinned microporous film to a nonwoven material. As a result, the laminate does not meet the ASTM-F1670-95 test. To overcome this problem, US Pat. No. 6,238,767 describes a calendering technique with a smooth roll that joins a microporous film and a nonwoven material.
The difficulty of obtaining a heat bonded laminate of nonwoven and microporous film that passes the ASTM-F 1670-95 test will be further increased when the nonwoven web is treated with a non-rigid surfactant. When such a web is thermally bonded to the microporous film, it is believed that some of the non-rigid surfactant present in the web is transferred to the film itself in the bonding zone by the heat and pressure of the thermal bonding process. When a liquid such as water, blood, or urine comes in contact with this surfactant present in the microporous region of the film, the resulting surface tension of the liquid is sufficient to pass through the microporous network. Decrease. Such laminates do not pass the blood bleeding standards described in ASTM-F1670-95. The pressure and temperature used in the thermal bonding process are believed to cause intimate contact between the surfactant, the nonwoven polymer and the polymer or other material present in the film in the bonding region. As a result, the surfactant is present in the microporous region, and it is thought that the surface tension of the liquid in contact with the region is reduced and the liquid can pass through the laminate.

A common technique used to counteract the effects of surfactant contamination on the film is to avoid the effect entirely by attaching the film to the surfactant treated nonwoven web via an adhesive. . As long as the bonding is not due to heat and the film and the surfactant-treated nonwoven are physically separated, the reduction in the surface tension of the liquid in the microporous region is eliminated or minimized. . Another technique is to thermally bond the film to a web that does not contain a surfactant. Once bonding is achieved, the film / nonwoven laminate can be treated locally with a surfactant to make it hydrophilic as a subsequent step. U.S. Pat. No. 5,901,706 to Griesbach et al. Describes laminates made by adhesive attachment or by thermal bonding followed by treatment with a surfactant suitable for surgical drape.
Finally, prior to the present invention, thermal bonding of the microporous film to the surfactant treated nonwoven web allows the film / nonwoven laminate to pass the ASTM-F1670-95 blood bleed criteria. It was thought that the liquid barrier property required for the liquid crystal could not be reliably provided.

  The present invention is directed to a disposable absorbent laminate comprising a melt-spun nonwoven material that has been surface treated with a surfactant and one or more layers thermally bonded to a breathable film, and a method of making the same. Such laminates are useful for surgical drapes, disposable work garments such as gowns, coveralls and laboratory garments, and personal care such as diapers, training pants, incontinence garments, sanitary napkins, bandages, wipes, etc. Has the use of absorbent products. In accordance with the present invention, the laminate provides excellent liquid absorbency, produces relatively little lint particles and passes the ASTM-F1670-95 blood bleed standard, and NFPA 702-1980 class 1 flammability conditions And maximizing drape strength at a relatively low cost. Accordingly, the present invention is directed to a laminate comprising a nonwoven web that has been treated with a surfactant and a stretched film. The stretched film comprises a core layer and at least one skin layer. The core layer has a percentage of the micropore generating filler material that is incorporated into the core layer. The stretched film is stretched at least in one direction to a percentage of its original size until the desired vapor permeability level is reached. The film is thermally bonded to the surfactant treated nonwoven material. The end result is a laminate having an exposed surface that forms a breathable barrier and passes through blood bleed through in accordance with ASTM F1670-95 and can absorb aqueous liquids.

In another embodiment, the present invention is directed to a breathable absorbent laminate according to ASTM F1670-95. The laminate comprises a nonwoven web treated with a surfactant. The nonwoven web is thermally bonded to the multi-layer polyolefin resin film at a plurality of bond points, at least some of the bond points forming an attachment between the web and the multi-layer film. At least one layer of the multilayer film contains some percent of microporous filler by weight.
In another embodiment, the present invention is directed to a surgical drape comprising a thermally bonded laminate formed from a stretched multilayer filled film and a surfactant treated hydrophilic and absorbent meltspun nonwoven web. It has been.
The laminates of the present invention provide improved liquid absorbency while passing the blood bleed through criteria described in ASTM-F1670-95 and provide class 1 flammability conditions of NFPA 702-1980 (20 seconds or more). While satisfying large flame propagation), it provides comfort, improved drape strength and meets the need in the art for materials with relatively low amounts of lint particles.
The laminate of the present invention can be formed from thermally bonding a film having at least one microporous layer and one or more nonwoven layers to include at least one hydrophilic melt spun fabric. . In general, the nonwoven filaments considered are formed from a hydrophobic polymer material. These materials are rendered hydrophilic by treatment with a hydrophilic chemical additive such as a surfactant in or on the filament.

As used herein, the term “polymer” generally includes, but is not limited to, homopolymers such as copolymers, terpolymers, and the like, such as block, graft, random, and alternating copolymers, and blends and modifications thereof. . Further, unless otherwise specified, the term “polymer” should include all possible geometric shapes of the molecule. These shapes include, but are not limited to, isotactic, syndiotactic, and random symmetries.
As used herein, the term “nonwoven” or “web” refers to a fabric having a structure of individual fibers or filaments that are randomly and / or unidirectionally deposited together in a mat. Nonwoven fabrics can be made by a variety of methods including, but not limited to, air deposition, wet deposition, water entanglement, short fiber carding and bonding, and solution spinning. Suitable nonwovens include, but are not limited to, spunbonded fabrics, meltblown fabrics, wet deposition fabrics, water entangled fabrics, spunlace fabrics, and combinations thereof. The basis weight of nonwovens is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm), and useful fiber diameters are usually expressed in microns. . (Note that osy is multiplied by 33.91 to convert from osy to gsm.)

As used herein, the term “melt-spun fabric” refers to a melted thermoplastic material or more than one melted thermoplastic material that is spun into a plurality of fine, usually circular, extruded filaments or fiber diameters. It refers to a nonwoven web of filaments or fibers formed by extrusion or coextrusion from the capillaries of the die. Melt spun fabrics include, but are not limited to, spunbond fabrics and meltblown fabrics, which are characterized by having heat bonded joints throughout the fabric.
As used herein, the term “spunbonded fabric” or “spunbond fabric” refers to a melted thermoplastic material or more than one melted thermoplastic material, and a plurality of fine, usually circular spinnerets. Small diameter formed by extruding or co-extruding from a capillary and rapidly reducing the diameter of the extruded filament, for example, by drawing fluid in a non-extractable or extractive manner, or by other known spunbond mechanisms Refers to a continuous filament web. These small diameter filaments are substantially uniform with respect to each other. The diameter characterizing these filaments ranges from about 7 to 45 microns, preferably from about 12 to 25 microns. The manufacture of spunbonded nonwoven webs is described in U.S. Pat. No. 4,340,563 to Appel et al., U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. US Pat. Nos. 3,338,992 and 3,341,394, US Pat. No. 3,276,944 to Levy, US Pat. No. 3,502,538 to Petersen, granted to Hartman U.S. Pat. No. 3,502,763 and U.S. Pat. No. 3,542,615 granted to Dobo et al. And Canadian Patent No. 803,714 granted to Herman.

  As used herein, the term “meltblown fabric” refers to extruding molten thermoplastic material from a plurality of fine, usually circular die capillaries as molten yarns or filaments into a high velocity gas (eg, air) stream. Refers to a fabric made of fibers formed by thinning a molten thermoplastic material filament and reducing its diameter to that of a “microfiber”. The meltblown fibers are then carried by the high velocity gas stream and deposited on the collecting surface to form a randomly dispersed web of meltblown fibers. The meltblown process is well known and A. Wendt, E .; L. Boone and C.I. D. Fluharty, “Manufacture of Super-Fine Organic Fibers”, NRL Report 4364, and K.K. D. Lawrence, R.A. T.A. Lukas and J.A. A. Young, "An Improved Device for the Formation of Super-Fine Thermoplastic Fibers", NRL Report 5265, and U.S. Pat. No. 3,849,241 issued November 19, 1974 to Buntin et al. .

As used herein, the term “microfiber” means a small diameter fiber having an average diameter of about 100 microns or less, eg, a diameter from about 0.5 microns to about 50 microns. More specifically, the microfibers may have an average diameter from about 1 micron to about 20 microns. Microfibers having an average diameter of about 3 microns or less are usually referred to as ultrafine microfibers.
As used herein, the term “multilayer laminate” refers to a spunbond / meltblown / spunbond (SMS) laminate, where some of the layers are spunbond (S) and some are meltblown (M). Laminate and Block et al. U.S. Pat. No. 4,041,203, Collier et al. U.S. Pat. No. 5,169,706, Potts et al. U.S. Pat. No. 5,145,727, Perkins et al. U.S. Pat. 178,931, and other laminates disclosed in Timons et al. US Pat. No. 5,188,885. Such a laminate is formed by sequentially depositing a spunbond fabric layer, then a meltblown fabric layer, and finally another spunbond layer on a moving forming belt, and then bonding the laminate in the manner described below. Can be manufactured. Such fabrics typically have a basis weight of about 0.1 to 12 osy (about 3.4 to 400 gsm), or more specifically about 0.4 to about 3 osy (about 14 to 100 gsm). Multi-layer laminates may also have various numbers of meltblown layers or multiple spunbond layers in many different configurations, such as other materials in film (F) or coform materials such as SMMS, SM, SFS, etc. May be included.

As used herein, the term “multilayer film” or “multilayer filled film” means a film having a number of contacting adjacent layers, each layer being uniformly distributed in the planar dimensions of the film. ing.
As used herein, the term “spun lace fabric” refers to a web of material composed of one or more types of non-continuous fibers in which the fibers are not bound to binder material or thermal bonding. Water entangled to achieve mechanical coupling.
As used herein, the term “wet-deposited fabric” refers to a fabric formed by a process such as a papermaking process, in which fibers or filaments dispersed in a liquid medium are deposited on a screen. And the liquid medium will flow through the screen, leaving a cloth on the surface of the screen. The fiber binder may be added to the fibers in the liquid medium or after being deposited on the screen. The wet deposition fabric may contain natural and / or synthetic fibers.
As used herein, the term “water entanglement” or “water entanglement” refers to a web of material consisting of one or more types of fibers or filaments exposed to a high speed water jet and the fibers entangled. It refers to the process in which mechanical coupling is achieved.

As used herein, the terms “breathable” and “microporous” refer to materials that are permeable to vapor and / or gas but that form a barrier to the permeation of liquid. This term usually have a minimum water vapor transmission rate of approximately 100g / m ^2/24 hours (WVTR), it refers to a material that can be passed through the steam. The fabric's WVTR, in one aspect, is the water vapor transmission rate that gives an indication of how comfortable the fabric is to wear. WVTR is measured as described below, the results are reported in grams / m ^2/24 hours. However, the use of breathable barriers, in many cases, it is desirable to have a high WVTR, breathable barrier of the present invention, about 300g / m ^2/24 hr, 800g / m ^2/24 hours, 1500 g / m ² / or more than 24 hours, or can have a WVTR in excess also a 3000 g / m ^2/24 hours. Breathable films are well known in the art and can be produced by any known method.

As used herein, the term “hot spot bonding” refers to passing the fabric, web or multilayer fabric and / or web of fibers to be bonded between a heated calendar roll and an anvil roll. . Calendar rolls are usually, but not always, patterned in such a way that the entire fabric is not bonded across the entire surface of the fabric, and anvil rolls are usually flat. Thus, various patterns of calendar rolls have been developed for functionality and aesthetic reasons. An example of a pattern is taught in US Pat. No. 3,855,046 to Hansen Pennings. Typically, the percent bonded area varies from about 10% to about 30% of the area of the fabric laminate web. As is well known in the art, the laminate layers are held together by bonding and the filaments and / or fibers are bonded within each layer to provide integrity to each individual layer.
As used herein, the term “ultrasonic coupling” refers to hot spots by passing the fabric between a sonic horn and an anvil roll, as shown, for example, in Bornslaeger US Pat. No. 4,374,888. It means to perform a bonding process.
As used herein, the terms “non-rigid surfactant” and “surfactant” refer to chemicals that render a polymer surface hydrophilic and can be extracted to some extent from such surface by an aqueous fluid.

As used herein, “machine direction” or MD means the direction in which the fabric is manufactured. “Lateral” or CD means the direction on both sides of the fabric, that is, the direction substantially perpendicular to the MD.
As used herein, the terms “recovery” and “shrink” mean that the stretched material contracts when the biasing force is stopped, and then the material stretches by applying the biasing force. For example, a 1 inch relaxed and unbiased material is stretched 50% by stretching to a length of 1.5 inches, which is stretched that is 150% of the relaxed length. It will have a length. If this exemplary stretched material shrinks, it will recover to a length of 1.1 inches after the biasing and stretching forces are partially or completely released, and the material It will have 80% (0.4 inch) recovery. As used herein, a “micropore-generating filler” can be added to a polymer and does not interfere or adversely affect the extruded film formed from the polymer, but does not affect the entire film. It is meant to include particles and other shaped materials that can be dispersed in a similar manner. In general, the microporous filler is in particulate form and will usually have a slightly spherical shape, with an average particle size in the range of about 0.5 to about 8 microns. The film will usually contain at least about 30% microporous filler based on the total weight of the film layer. Both organic and inorganic microporous fillers are within the scope of the present invention provided they do not interfere with the film forming process, the breathability of the resulting film, or the ability of the film to be bonded to the fibrous polyolefin nonwoven web. Is considered to be contained within.

  Referring to FIG. 1, there is shown a laminate 10 according to the present invention comprising a laminate film 14 and a surfactant treated nonwoven web 12 bonded thereto. Bonding the web 12 to the film 14 is accomplished at least in part at the bond point 16 by hot spot bonding, i.e., using heat and / or pressure with a heated bond roll at least one of which is patterned. Is done. The multilayer film 14 includes a plurality of layers that can include a core layer 18 and one or more skin layers 20 on either side of the core layer 18. Each of the skin layers 20 may further include an extrudable thermoplastic polymer and / or additive that imparts special properties to the film 14. As shown in FIG. 1, at least one skin layer 20 (two shown in the embodiment of FIG. 1) and nonwoven web 12 are overlaid on each other such as face-to-face or surface-to-surface. Arranged with respect to. Web 12 and film 14 or both are joined together over the entire surface or at least a portion of the respective surface, such as thermal bond point 16. The web 12 or film 14 of the laminate 10 may have different shapes and dimensions. However, in many embodiments, the web 12 and film 14 are substantially similar in shape and are coextensive with respect to each other.

In some embodiments, as described below, the nonwoven web 12 may include a surfactant-treated spunbond layer. Another embodiment includes a nonwoven web 12 in which at least one spunbonded layer and one or more meltblown fabric layers are combined, wherein the one or more fabric layers are within each fabric. It is rendered hydrophilic by incorporating a surfactant into or on it, thereby making the nonwoven web absorbent.
Another embodiment as shown in FIG. 2 contemplates sandwiching the multilayer film 14 between two nonwoven webs 12 and 22. Each of the nonwoven webs 12 and / or 22 may itself consist of a single layer of melt spun fabric, eg, spunbond or meltblown fabric, or each of the nonwoven webs 12 and / or 22 may be a plurality. Individual nonwoven webs, each of the individual nonwoven webs 12 or 22 being either the same web, a similar web, or a different web. For example, each of the webs 12, 22 may comprise a spunbond layer and a meltblown layer, or a first spunbond layer, a meltblown layer, and a second spunbond layer. Other layers and combinations are possible as well, depending on the intended use of the product. In any of the embodiments, any of the nonwoven webs can be treated with a surfactant to make them hydrophilic, and any of the webs can be treated with other surface modifiers.

  FIG. 3 shows an embodiment of the invention similar to FIG. 1, but FIG. 3 shows that the single layer nonwoven web is replaced with a multilayer nonwoven web 24. Any one or all layers of the nonwoven web 24 may be treated with a surfactant, and adjacent layers of the nonwoven web 24 may be formed from a heat miscible polymer. In the embodiment of FIG. 3, the nonwoven web 24 comprises a spunbond / meltblown / spunbond (SMS) laminate having a first spunbond layer 26, a meltblown layer 28, and a second spunbond layer 30. As in FIG. 1, the film 14 of FIG. 3 is composed of a plurality of layers including a core layer 18 and one or more skin layers 20 on either side of the core layer 18. Each skin layer 20 may include an extrudable thermoplastic polymer and / or an additive that imparts special properties to the film 14. As shown in FIG. 3, in any of the contemplated embodiments, the film can be positioned so that the film 14 forms the outer surface of the laminate 10.

  FIG. 4 shows another embodiment in which the multilayer film 14 is sandwiched between at least one nonwoven web 22 (however, can be replaced by the nonwoven web 12) and at least one multilayer nonwoven web 24. FIG. The embodiment of is shown. Any one or all of any one or all layers of the nonwoven web may be treated with a surfactant, but at least one nonwoven layer in at least one nonwoven web is hydrophilic. It is desirable that While various combinations are contemplated, one possible embodiment of the laminate 10 is itself a spunbond / meltblown / spunbond (first spunbond layer 26, meltblown layer 28, and second spunbond layer 30). Including a non-woven web 24 comprising an SMS) laminate laminated to the film 14. The nonwoven web 12 is bonded to the opposite side of the film 14 so that the film 14 is sandwiched between the webs 22 and 24. At least one of the layers 26, 28, or 30 is surfactant treated.

As is apparent from the above description and drawings, many combinations and amounts of single and / or multilayer webs and films are possible. Furthermore, there are many possibilities as to which of these layers and / or webs are pretreated with a surfactant. In any case, in each embodiment, the film 14 can act to block penetration of external liquid through the laminate 10. Accordingly, the film 14 is attached to at least one adjacent layer of the laminate 10. In any of the embodiments, the film 14 can be attached to the nonwoven webs 12, 22, and / or 24 of the laminate 10 by hot spot bonding 16.
In some embodiments, film 14 may include an extrudable polyolefin having multiple layers, at least one of these layers containing a microporous filler. Still referring to FIG. 4, it can be seen that the core layer 18 of the film 14 contains such a micropore-forming filler 32. The micropore generating filler 32 gives the core layer 18 characteristics such as air permeability obtained by appropriate processing. Therefore, the filler 32 can be dispersed throughout the core layer 18. Typically, the film 14 is rendered breathable by adding filler 32 to the film 14 during the film forming process and then subsequently stretching the film to create pores in or around the filler 32. This makes the film breathable and allows water vapor and other gases to permeate into and through the micropores created through and through the film in and near the pores. It is possible to suppress the permeation of the liquid. The microporous filler 32 may also be included in the skin layer 20 for desirable properties such as breathability, anti-blocking properties, improved attachment to the nonwoven web, and the like. Of course, all embodiments, including those shown in FIGS. 1-3, consider the use of such micropore-generating fillers 32.

Most typically, such filler material 32 used in the core layer 18 of the film 14 is primarily used, for example, in weight percentages ranging from about 25% to about 60% based on the total weight of the layer 18. The amount of filler material 32 can vary widely as long as the desired degree of liquid impermeability throughout the film 14 is maintained.
Suitable polymers for core layer 18 include polyethylene, polyethylene blends, polypropylene, polypropylene blends, polyethylene and polypropylene blends, polyethylene or a combination of polypropylene and a suitable amorphous polymer blend, ethylene monomers and propylene monomers. And copolymers of such copolymers with polyethylene or polypropylene, or suitable amorphous polymers, semi-crystalline / amorphous polymers, “heterophasic” polymers, or combinations thereof. Examples of useful polymers that can be included in the polymer portion of core layer 18 are EXXPOL®, EXCEED® and EXACT® polymers from Exxon Chemical Company, Baytown, Midland, Michigan. ENGAGE (R), ACHIEVE (R), ATTAIN (R), AFFINITY (R), and ELITE (R) polymers from Dow Chemical Company, and Basell USA Inc., Wilmington, Delaware. From CATALLOY® polymer. Other useful polymers include elastomeric thermoplastic polymers.

Each of the skin layers 20 may be formed from a polymer that provides antibacterial activity, water vapor permeability, adhesion, and / or tack-free properties, and may contain a micropore-generating filler 32. Suitable polymers for skin layer 20 include polyolefin homopolymers, copolymers and blends, CATALLOY® polymers, ethylene vinyl acetate (EVA), ethylene ethyl acrylate (EEA), ethylene acrylic acid (EAA), ethylene methyl acrylate. (EMA), ethylene butyl acrylate (EBA), polyester (PET), nylon (PA), ethylene vinyl alcohol (EVOH), polystyrene (PS), polyurethane (PU), and amorphous ethylene propylene random copolymer are mainly half An olefinic thermoplastic elastomer that is the product of a multi-stage reactor that is molecularly diffused into a continuous high-polypropylene monomer / low-ethylene monomer matrix that is crystalline can be used alone or There are polymers and polymer blends used in combination.
A more detailed description of a film having a core layer and a skin layer is assigned to the same assignee as the present invention and is incorporated herein by reference in its entirety, US Pat. Nos. 5,695,868, 6, See 075,179 and 6,238,767.

Examples of certain possible microporous filler materials 32 incorporated into the core layer 18 include calcium carbonate (CaCO ₃ ), various clays, silicon (SO ₂ ), alumina, barium sulfate, sodium carbonate, talc, magnesium sulfate, Titanium dioxide, zeolite, aluminum sulfate, cellulose type powder, diatomaceous earth, magnesium sulfate, magnesium carbonate, barium carbonate, kaolin, mica, carbon, calcium oxide, magnesium oxide, aluminum hydroxide, pulp powder, wood powder, cellulose derivative, polymer Particles, chitin and chitin derivatives. The microporous filler material 32 can optionally be coated with a fatty acid such as stearic acid or a large chain fatty acid such as behenic acid, which facilitates free flow (in bulk) of the particles. And can be easily dispersed in the polymer matrix. Also, the silicon-containing filler may be present in an amount effective to impart tack-free properties.
Filler materials that can be incorporated into the skin layer 20 include calcium carbonate (CaCO ₃ ), various clays, silicon (SO ₂ ), and the like. A particularly useful filler is a silicon-containing filler such as diatomaceous earth that imparts tack-free properties to the film when present in an effective amount.

In some multilayer films 14, the core layer 18 may comprise polyethylene filled with about 60% by weight of calcium carbonate that serves as the micropore filler 32. The skin layer 20 may comprise a suitable CATALLOY® polymer. Such CATALLOY® polymers may include copolymers of ethylene. The skin layer 20 may also contain an additive in order to impart non-tackiness. The overall ratio of skin layer 20 to core layer 18 can be approximately 4.5% to 12% by weight. In another multilayer film 14, the core layer 18 is as described above, but the skin layer 20 is a polymer of a suitable CATALLOY® polymer and an EVA polymer having a vinyl acetate content of about 28%. Blends may contain diatomaceous earth or other additives added or not added to impart tack-free properties.
It is contemplated that the absorbent component of the laminate 10 is any one or all of the nonwoven webs 12, 22, and / or 24. The web can be formed by a number of methods including, but not limited to, spunbond and meltblowing methods. Regardless of the number of layers or their particular configuration, the actual material used to make any of the nonwoven webs can form single and / or multi-components, or conjugates, fibers or filaments. It may include synthetic filaments and / or fibers that can be made from a variety of known thermoplastic polymers.

  Suitable polymers for forming the nonwoven web of the present invention include, but are not limited to, polyolefins such as polyethylene, polypropylene, polybutylene, and the like. Of the polymers suitable for forming the conjugate fibers, polymers particularly suitable for the high melting point component of the conjugate fibers include polypropylene, copolymers of propylene and ethylene or blends thereof, polyesters, and polyamides, and more Specifically, polypropylene. A particularly suitable polymer for the low melting point component is polyethylene, more specifically linear low density polyethylene, high density polyethylene and blends thereof. The most suitable constituent polymers for the conjugate fibers are polyethylene and polypropylene. Particularly suitable polymers for forming the nonwoven web include narrow molecular weight distribution polymers such as metallocene catalyzed polypropylene, particularly metallocene catalyzed inelastic polypropylene. In addition, the polymer component may be a thermoplastic elastomer blended therein, or to enhance crimpability and / or reduce fiber bonding temperature and the resulting web's abrasion resistance, strength and flexibility. Additives that enhance the properties may be included. Still other suitable polymer additives include polybutylene copolymers and ethylene-propylene copolymers.

  In some embodiments, one or more hydrophilic additives are added to the polymer melt to form a hydrophilic melt spun fabric. Particularly useful hydrophilic additives are surfactants that are non-toxic, have low volatility, and are well soluble in molten or semi-molten polymers. In addition, the hydrophilic additive is thermally stable at temperatures up to 175 degrees Celsius and is sufficiently delaminated so that the additive can be incorporated into the polymer filament without the need to apply heat as the filament solidifies. It is desirable to move from most to the surface of the polymer filament. At the polymer surface, the additive modifies the polymer surface so that when contacted with an aqueous fluid (by reducing the surface tension of the aqueous liquid), the surface of the polymer is immediately wetted. Such additives include, but are not limited to, the following additives: (i) polyoxyalkylene modified fluorinated alkyl, (ii) polyoxyalkylene fatty acid ester, (iii) polyoxyalkylene modified polydimethylsiloxane And PEG-terephthalate (polyethylene glycol modified terephthalate), and (iv) ethoxylated alkylphenols, one or a combination of additives. An example of a suitable polyoxyalkylene modified fluorinated alkyl is FC-1802, a product of Minnesota Mining and Manufacturing Company. An example of a suitable polyoxyalkylene fatty acid ester is PEG-400ML, a product of Henkel Corporation / Energy Group. An example of a suitable polyoxyalkylene-modified polydimethylsiloxane is MASIL® SF-19, a product of PPG Industries. An example of a suitable ethoxylated alkylphenol is Triton® 102, a product of Union Carbide. The choice of one or more additives depends on, for example, cost, compatibility with the polymer material, and overall contribution to the properties of the laminate. A process for modifying a hydrophobic polymer to be hydrophilic by adding a surfactant to the polymer melt is shown in patents such as US Pat. No. 5,759,926 to Pike et al. This is incorporated herein by reference in its entirety.

  Alternatively and / or additionally, hydrophilic additives, particularly surfactants, may be added to the melt spun fabric after forming the fabric. Suitable methods for adding the hydrophilic additive to the melt spun fabric include, but are not limited to, foam coating, spray coating, or solution coating. In embodiments where the hydrophilic properties of the absorbent fabric are due to hydrophilic additives added to the surface of the fabric filaments, the hydrophilic additive is any additive that is thermally stable at temperatures up to 60 degrees. There may be. At the filament surface, the additive changes the intrinsic hydrophobicity of the filament surface such that the filament surface wets when contacted with the aqueous fluid (by reducing the surface tension of the aqueous fluid). Such additives include, but are not limited to, those specified above and those with thermal stability up to 60 degrees. Any of these additives are suitable for the present invention so long as they do not adversely affect the desired properties of the resulting laminate. Furthermore, the hydrophilic melt spun fabric and other components making up the absorbent laminate of the present invention may also be treated with any known antistatic agent. A process for rendering a hydrophobic polymer hydrophilic by surface treating the fibers is shown in Krzysik et al. US Pat. No. 6,204,208, which is incorporated herein by reference in its entirety.

Generally, the concentration of the hydrophilic additive in or on the filaments or fibers that comprise the melt spun fabric (eg, spunbonded filaments or meltblown microfibers) should be from about 0.05% to about 5.0% by weight Can do. Further, the concentration of the hydrophilic additive in or on the filaments or fibers making up the melt spun fabric can be from about 0.1% to about 1.5% by weight.
The selection of one or more hydrophilic additives depends on, for example, the overall contribution to cost, compatibility with the polymer material, and final drape characteristics. Hydrophilic melt spun webs provide superior liquid absorbency to the laminates of the present invention as compared to normal or hydrophobic spunbonded fabrics. For use as a surgical drape, the laminate of the present invention provides comparable liquid absorbency without becoming flammable compared to commercially available drapes. In some embodiments, the hydrophilic melt spun fabric may have a basis weight of about 15 to about 140 grams per square meter (gsm). In another embodiment, the hydrophilic melt spun fabric may have a basis weight of about 20 to about 60 grams per square meter (gsm).

The hydrophilic melt spun web of the present invention may also be treated with various chemicals or contain various chemicals to impart additional desirable properties. Any of these chemicals are suitable for the present invention as long as the chemical does not adversely affect the desired properties of the laminate. For example, the hydrophilic melt spun web may be treated with any known antistatic agent, flame retardant, or other desirable chemical finish. Further, in hospital related applications of the laminate of the present invention, it is desirable to treat the web to be conductive to prevent electrostatic charging. One way in which this result can be achieved is to apply a normal salt solution, such as lithium nitrate, to the continuous filament web before or after making the melt spun fabric. In one embodiment, the surfactant and salt solution are combined and then applied to the melt spun fabric in one processing step.
In the practice of the present invention, a single nonwoven web layer 12 may be laminated to the film layer 14 as shown in FIG. An example is a spunbond (S) / film (F) laminate. Alternatively, a plurality of nonwoven web layers may be incorporated into the laminate, similar to the embodiment of FIGS. Examples of such materials include, for example, SFS multilayer laminate composites. Another example is a meltblown (M) / F laminate, an SMS / F laminate. In fact, any combination of surfactant treated nonwoven webs, layers, or a single layer within the nonwoven web that is bonded to the microporous film is contemplated. In one possible embodiment, the laminate can be used as a surgical drape. In the surgical drape embodiment, the outermost layer facing away from the patient may comprise a hydrophilic melt spun web.

  If the laminate 10 is comprised of a hydrophilic melt spun fabric and a film (ie, the embodiment of FIG. 1 or a similar configuration), it is desirable for the film to contact the patient. The film may have protrusions as described in US Pat. No. 5,546,960 or other three-dimensional features that minimize patient contact. As a surgical drape, the laminate of the present invention may be provided with one or more fenestrations (not shown). In some such applications, each of the fenestrations is usually sized to overlap the patient's surgical site and provide a means for the healthcare provider to access the site. The fenestration may extend through one or more layers of the surgical drape and can be dimensioned depending on the intended use of the surgical drape. In addition, the surgical drape may include other components such as a cutting material, a release layer over the cutting material, a pouch containing a surgical instrument, and other surgical drape components known to those skilled in the art. Although the described embodiment is directed to a surgical drape, the laminate of the present invention has many other uses. Other applications include, but are not limited to, patient preparation pads, examination table covers, patient mattress bed covers or liners.

  The laminate components of the present invention may be made by any method of making similar laminates known to those skilled in the art. A hydrophilic melt spun fabric may be made by adding a hydrophilic chemical additive to the polymer melt followed by forming melt spun filaments or fibers. Alternatively, the hydrophilic chemical additive may be coated on the melt spun fabric. These methods can also be used to make other nonwovens formed from essentially hydrophobic polyolefins used in combination with melt spun fabrics in absorbent drapes hydrophilic. Heat bonding together a hydrophilic melt spun fabric and film suitable for the present invention involves pressing such materials together against each other through a nip formed by a heated roll that rotates together, by ultrasonic bonding, and by hydrophilic bonding. The adjacent opposing surfaces of the adhesive melt spun fabric and the film can be achieved by other means of joining together in defined areas.

Some of the previously disclosed embodiments of the present invention (not shown) use a multilayer film 14 consisting of a particle-filled core layer 18 and a single skin layer 20. In at least one of the most basic configurations, one skin layer 20 is attached to the first outer surface of the core layer 18 simultaneously, usually by a coextrusion process, to form the multilayer film 14. In embodiments having this configuration, the multilayer film 14 defines an overall thickness, and the first skin layer 20 comprises a thickness of about 10% or less of the overall effective thickness of the multilayer film 14. The first skin thickness is determined.
The effective thickness of the film is used to take into account pores or air space in the breathable film layer. In normal, non-breathable, non-breathable films, the actual thickness and effective thickness of the film are typically the same. However, in a filler-filled film that has been thinned by stretching as described herein, the thickness of the film will also include the air space. In order to ignore this added volume, the effective thickness is calculated according to the test method described below.
For example, in certain embodiments, the thickness of the first skin layer 20 can be manufactured to not exceed about 5 microns. In another embodiment, the thickness of the first skin layer 20 can be manufactured to not exceed about 3 microns. In yet another embodiment, the thickness of the first skin layer 20 can be manufactured to not exceed about 2 microns. Such a thickness can be achieved by stretching the film 14 to such an extent that the multilayer film 14 is thinned to the dimensional range defined herein.

In the case of a multilayer film 14 comprising a core layer 18 sandwiched between two skin layers 20 as shown in each of FIGS. 1-4, possible embodiments include a first skin layer and a second skin. It is defined that layer 20 has a combined thickness that does not exceed about 15% of the overall thickness of multilayer film 14. Another embodiment provides that the first skin layer and the second skin layer 20 have a combined thickness that does not exceed about 8% of the overall thickness of the multilayer film 14. Yet another embodiment provides that the first skin layer and the second skin layer 20 have a combined thickness that does not exceed about 6% of the overall thickness of the multilayer film 14. The skin layer 20 can also be formed so that it does not exceed about 3% of the overall thickness of the multilayer film 14.
Furthermore, it is not necessary for each skin layer 20 to have the same dimensions. For example, one of the skin layers 20 can range from about 0 to about 15% and the other of the skin layers 20 can range from about 15% to about 0%. In some embodiments, the film 14 in the final laminate may have a film thickness from about 0.3 mil (about 8 microns) to about 1 mil (0.025 mm). In other possible embodiments, the film 14 may have a film thickness from about 0.5 mil (about 13 microns) to about 0.8 mil (about 20 microns). The film 14 in the final laminate may also have a film basis weight of less than about 25 grams per square meter (gsm). Further, the film 14 in the final laminate may have a film basis weight that is less than about 20 gsm. Also, such thickness and basis weight ranges can be used for any of the embodiments discussed herein.

  In any event, the particulate filler-filled film 14 is formed and then stretched to create pores around or near the filler particles throughout the core layer 18, which imparts air permeability to the layer 18. Proper selection of the type and amount of polymer and filler in each skin layer 20 ensures that after stretching, such layer 20 does not impede the permeation of water vapor or other gases through the film 14. In forming the individual layers 28 and 30 of the film 14, the layers 28 and 30 may be coextruded to ensure interfacial contact and reduce processing complexity. The method for forming the film 14 is generally known. Film 14 can be formed from either a cast or blown film apparatus and can be co-extruded and embossed if desired. Furthermore, the film 14 can be stretched or stretched by passing the film 14 through a film stretching apparatus. In general, this stretching can be done on CD or MD or both.

We have stretched the multilayer film 14 described in the embodiments, and then thermally bonded them under certain conditions to a melt spun web that has been pre-treated with a surfactant, so that the water-based fluid can penetrate. It has been found that a laminate can be obtained that reliably prevents The composition of the layers in the film and the ratio of the thickness of each layer is determined by the liquid bleed after the stretched film is hot spot bonded to a nonwoven web made absorbent by treating the web with a surfactant. It is an element for maintaining a certain degree of air permeability while maintaining a consistent resistance. More importantly, as the film is stretched, significant continuity is maintained in the skin layer adjacent to the surfactant treated nonwoven web while the core layer is microporous.
The inventors have shown that shrinking the multilayer film after stretching and before thermal bonding to the surfactant-treated melt spun fabric produces a laminate that reliably prevents the penetration of water-based fluids. I found it to be a method. Stretching of the stretched multilayer film has been described in relation to stretched multilayer films containing microporous fillers, for example, as previously cited US Pat. No. 6,045,900. Such shrinkage has been observed to improve the physical properties of the resulting film, such as large stretch before tearing in the direction of stretching. In the context of the present invention, applying appropriate processing conditions (eg stretching and shrinking) to the extruded film prior to lamination to the surfactant treated nonwoven web will enhance the desired fluid barrier properties. And / or as an element to maintain.

Referring to FIG. 5, the process of forming the laminate 10 of FIGS. 2 and 4 is shown. A co-extruded film device 34 forms a film 14 having multiple layers of skin layers and core layers (not shown). Typically, the device 34 will include two or more polymer extruders 36. In one manufacturing method, the film 14 may be extruded into a pair of nip or chill rollers 38, one of which may be patterned to impart an embossed pattern to the film 14. This is particularly advantageous for reducing matting and providing a matte finish. In another method, the film 14 can be extruded onto a chill roll and have a smooth or matte finish. Typically, film 14 will have an overall thickness of approximately 25 to 60 micrometers when initially formed, and in the case of a multilayer film, the sum of the skin layers or tie layers is For example, having an initial thickness that can be from about 3% to about 30% of the overall thickness.
From the co-extruded film device 34, the film 14 is directed to a film stretcher 40, such as a machine direction stretcher (MDO), which is commercially available from vendors such as Marshall and Williams Company, Providence, Rhode Island. . Such a device 40 has a plurality of pairs of stretch rolls 42. These paired stretch rolls move at a predetermined speed and may be rotated faster, slower, or at the same speed relative to each other. Typically, throughout the process shown in FIG. 5, the draw roll moves progressively at a higher speed to progressively stretch and thin the film 14 in the machine direction of the film. Some of the draw rolls 42 may optionally move at a slower speed than the previous draw roll 42 so that the film 14 can shrink in the machine direction as well. The draw roll 42 is typically heated for processing convenience. In addition, the unit 40 also includes a roll (not shown) that can be used to pre-heat the film 14 before stretching and to heat or cool the film after stretching, upstream from the stretching roll 42. It may also be included downstream.

After exiting the film stretching unit 40, the stretched film 14 can contract by an amount substantially less than the stretched amount. This shrinkage is such that the ratio of the speed of the film in the nip formed by roll 44 to the speed of the last set of draw rollers in draw unit 40 is less than 100%, preferably between about 70% and 90%. This is achieved by rotating the heated calendar roll 44 so as to satisfy the following range.
One possible film 14 can be seen in particular in FIG. 4, where the film comprises a core layer 18 made of polyethylene filled with about 60% by weight of calcium carbonate serving as a micropore-generating filler 32; From a multilayer film 14 comprising: 50% EVA having a vinyl acetate content of about 28%, a skin layer 20 comprising a polymer blend of 50% CATALLOY® KS-357P and 5% by weight of an anti-blocking agent. Become. The ratio of skin layer to core layer can range from about 4.5% to about 12% by weight. The initial thickness of the skin layer 20 on each side of the core layer 18 may be the same. Removal of such fillers 32 from the skin layer 20 is possible by film forming in-line and laminating to a non-woven material.

  Still referring to FIG. 5, when the multilayer film 14 is extruded, the film is stretched by a stretching unit 40 having a stretching roll at a temperature of about 160 degrees Fahrenheit to about 220 degrees Fahrenheit. After film 14 is sufficiently thin and before the stretched film passes through the last set of draw rolls 42, film 14 is brought to a temperature between about 160 degrees Fahrenheit and about 220 degrees Fahrenheit. Slightly shrinks while maintained. After the film 14 exits the stretching unit 40, the film further shrinks before being thermally bonded to the nonwoven webs 12, 22, and / or 24 with a calendar roll 44. This cumulative shrinkage appears to have the beneficial effect of thickening and reducing any pores formed in the skin layer 20. Films that have undergone this treatment will have a breathability between about 300 WVTR and about 3500 WVTR.

In some embodiments, the multilayer film 14 and the nonwoven web, such as 12 and 22, are then combined together to form a heated calender roll 44 comprising a smooth steel roll and a patterned steel roll. And laminated together. These rolls 44 have a discrete bond pattern with a defined bond surface area for the resulting laminate. In general, the maximum bonding point surface area for a given area on one side of the laminate 10 does not exceed about 50% of the total surface area. There are many individual bond patterns that can be used, all of which typically have a bond point surface area of between 15% and 30%. Laminate 10 may exit calendar roll 44 and then be wound on roll 46 for later processing. Alternatively, the laminate 10 may continue to be inline for further processing or conversion.
Similar processes may be used to form a laminate 10 of film 14 and a single nonwoven web, such as web 12 as shown in FIGS. The modification of the process already described uses only one nonwoven web layer 12, and the nonwoven web 12 and film 14 are placed so that the desired skin layer 20 is adjacent to the face of the desired nonwoven web 12. Arranging and adjusting the bonding temperature at the calendar roll 44 so that hot spot bonding occurs between the film 14 and the nonwoven material 12.

The temperature at which the film 14 is heated while stretched will depend on the composition of the film, as well as the breathability and other desired final properties of the laminate 10. In most cases, the film is heated to a temperature not higher than 5 degrees below the melting point of the core layer in the film. The purpose of heating the film is to allow it to stretch quickly without causing film defects. The amount stretched depends on the polymer composition, but usually the film is up to about 300% or more of the original length (ie, a length of 1 cm would be stretched to 3 cm, for example). Thus, it can be stretched to an amount less than that which would cause film defects. In most applications, for example, the stretching will be at least 200% of the original film length, often in the range of about 250% to 500%. Laminating the nonwoven web and film is accomplished by the heat and compressive force applied by the calendar roll 44. The strength of the hot spot bond that attaches the hydrophilic nonwoven web and film to each other can be measured by peel strength. After thermal bonding, if necessary, the laminate 10 may be heated or cooled by methods known to those skilled in the art (not shown).
The present invention has been described above by way of example only and is not to be construed as limiting the scope of the invention in any way. On the contrary, after reading the description herein, other embodiments, modifications and equivalents may be made to those skilled in the art without departing from the spirit of the invention and / or the scope of the claims. Clearly understood. In the examples, reference is made to certain data measured by certain tests. These tests are described below.

Film thickness The overall thickness of the film was measured in cross section from a micrograph. As one method of obtaining a micrograph, a field emission scanning electron microscope (FESEM) and the following preparation procedure were used. Each film sample was immersed in liquid nitrogen and cut by impact with a razor blade. The freshly cut section was attached to the specimen stub in an upright state using copper tape. Scanning photomicrographs were taken at a magnification of approximately 2000X to see each film structure. For each multilayer film sample, three individual specimens and two photomicrographs corresponding to each specimen were prepared and the dimensions of these photographs were measured directly. In order to calibrate the dimensions, a reference scale was superimposed on each photomicrograph. At least three measurements were taken for each micrograph, thereby producing a set of at least 18 data points or measurements for each film sample used to determine thickness. From each data point set for the corresponding film sample, the average thickness value for each film sample was calculated in microns.

Effective thickness The effective thickness of the film material was calculated by dividing the basis weight of the film by the density of the polymer and filler forming the film. Density can be readily determined from vendor information or commercially available references. To obtain the effective thickness of the film material in inches, multiply the weight per unit area measured in ounces per square yard (osy) by 0.001334 (a factor that converts UK units to metric) and the result Was divided by the density of the polymer blend in grams per cubic centimeter (g / cc).

Water vapor transmission rate test The water vapor transmission rate (WVTR) for the sample material was calculated according to normal ASTM standard E96-80. A 3 inch diameter (7.62 cm) round sample was cut from each of the test materials and a control that was a piece of CELGARD® 2500 film from Hoechst Celanese Corporation, Somerville, NJ. CELGARD® 2500 film is a microporous polypropylene film. Three specimens were prepared for each material. The test dish was a number 681 vaporometer cup distributed by Thwing-Albert Instrument Company, Philadelphia, Pennsylvania. 100 milliliters (ml) of distilled water was poured into each wepometer cup and individual samples of test and control materials were placed over the top of the individual cup openings. Tighten the threaded flange to form a seal along the edge of each cup (without sealant grease) and related across a 6.5 centimeter (cm) diameter circle with an exposed area of approximately 33.17 square centimeters The test or control material to be left exposed to the ambient atmosphere. The cup was weighed and placed in a forced air oven set at a temperature of 37 ° C. (100 ° F.). The oven was a constant temperature oven in which outside air was circulated in order to prevent water vapor from collecting inside. A suitable forced air oven is, for example, Blue M Electric Co., Blue Island, Illinois. Blue M Power-O-Magic 60 ovens distributed by After 24 hours, the cup was removed from the oven and weighed again. The water vapor permeability value of the preliminary test was calculated as follows.

Test WVTR = (number of weight loss grams over 24 ^{hours) × 315.5 (g / m 2} /24 hours)

The relative humidity in the oven was not particularly controlled. A predetermined set conditions of 100 ° F (37 ° C.) and ambient relative humidity, CELGARD WVTR of (R) 2500 film control has become 5000 grams per square meter per 24 hours (g / m ^2/24 hours) Has been located. Therefore, a control sample was associated with each test and the preliminary test values were corrected to the prescribed conditions using the following formula:

WVTR = (Test WVTR / control ^{WVTR) × 5000g / m 2/} 24 hours (g / m ^2/24 hours)

Other methods of determining WVTR using other test systems are possible. One particular test system used to measure WVTR values for some of the examples and comparative examples of films and laminates is available from Modern Controls, Inc., Minneapolis, Minnesota. It was a PERMATRAN-W 100K water vapor transmission analysis system commercially available from (MOCON).

Blood bleed through test blood barrier results were measured according to ASTM F1670-95. In this test, test strips are exposed to simulated synthetic blood for a specified time and pressure sequence. Only visual observation is used to determine when or if penetration has occurred. Report the result as acceptable (“conform”) or unacceptable.
Hydrostatic Pressure (Hydrohead Pressure) Test The hydrostatic pressure test measures the resistance of a nonwoven material to water permeation under low hydrostatic pressure. This test procedure is a federal test method standard no. 191A method 5514, AATCC test method 127-89, and INDA test method 80.4-92 modified to include support for synthetic fiber window screen materials available at any hardware store. Schmid Corp., Spartanburg, South Carolina. A test head of Textest FX-300 Hydrostatic HeadTest available from is filled with pure water. The pure water is maintained at a temperature between 65 degrees Fahrenheit and 85 degrees Fahrenheit (18.3 to 29.4 ° C.), which is normal ambient conditions (about 73 degrees Fahrenheit (23 ° C.) and a relative humidity of about 50 degrees. %) And the test was conducted under the conditions. A sample of 8 inch x 8 inch (20.3 cm x 20.3 cm) square test material was placed so that the test head reservoir was completely covered. The sample was subjected to a standardized water pressure that was increased at a constant rate until leakage was observed on the outer surface of the sample material or the desired hydrostatic pressure was achieved. Hydrostatic resistance was measured when the first signs of leakage were seen in three separate areas of the sample. This test was repeated for five specimens of each sample material. The hydrostatic resistance results for each specimen were averaged and recorded in millibars (mbar). Higher values indicate greater water permeation resistance.

Peel Test To determine peel strength, test for the amount of tensile force that will pull the layers of the laminate apart. The magnitude of peel strength is obtained using a 4 inch (10.2 cm) wide cloth, a width of the weider clamp, and a constant spread rate of 12 inches (30.5 cm) per minute. The film side of the specimen is covered with masking tape or other suitable material that prevents the film from being torn during testing. Since the masking tape exists only on one side of the laminate, it does not contribute to the peel strength of the sample. Remove by hand enough to allow the sample to be clamped in place. Test specimens were prepared according to, for example, 02021 in Massachusetts, Washington, St. Instron Model ™ available from Instron Corporation, 2500, or Datton St., 19154, Philadelphia, Pennsylvania, with a long parallel clamp of at least 4 inches (10.2 cm). Thwing-Albert Instrument Co., 10960. Clamp to Thwing-Albert model INTELLECT II available from The sample specimen is then pulled apart at a rate of 300 mm (about 12 inches) to 180 degrees of separation and the tensile strength is recorded in grams force per 4 inches as an average based on the curve generated.
Absorbency test This test is performed in accordance with the federal specification UU-T-595b. This is done by cutting a test sample to 4 inches x 4 inches (10.2 cm x 10.2 cm), weighing it and then saturating with water for 3 minutes by immersion. The sample is then removed from the water and a corner is hung for 30 seconds to drain excess water. The sample is then reweighed and the difference between the wet weight and the dry weight is the water absorption of the sample expressed in grams per 4 inch × 4 inch sample. The percentage of absorbency (% absorbency) is obtained by dividing the total water absorption by the dry weight of the sample and multiplying it by 100.

(Example of the present invention)
All films in the examples were multilayer films having two outer or skin layers that were the same in each example, with an intermediate or core layer sandwiched therebetween. All films were cast films and all films were embossed before being stretched to provide a matte finish on one of the outer surfaces. Tables 1, 2 and 3 include measurements and measurements made in accordance with the previously described methods that characterize selected properties of the film laminate.

Example 1
In this example, the film used was cast co-extruded skin-core-skin, or both Dow Chemical Co. Approximately 39% by weight Dow 3310 and approximately 2.8% Dowlex 4012, 0.2% CIBA B900 antioxidant, 58% Supercoat®, and available from English China Clay It was an “ABA” film with a core layer containing stearic acid-coated CaCO ₃ with a fine powder. The two outer or skin layers on either side of the core layer are 50% 760.36 ethylene vinyl acetate (EVA) from Exxon Chemical Company and Basell USA Inc. Consists of 4.5% polymer blend with 50% KS357P CATALLOY® polymer from (Wilmington, Del.) And approximately 4% Ampacet 10115 anti-blocking agent. Ampacet 10115 anti-blocking agent contains approximately 20% by weight of Superfloss® diatomaceous earth and is available from Ampacet Corporation, Tarrytown, NY. The three-layer film was extruded using a cast co-extrusion device of the type described to give an unstretched film having a thickness of approximately 51 microns (2 mils). The film was wound on a roll and later sent to a machine direction stretcher (MDO). The MDO unit was preheated from 185 ° F. to 210 ° F. (85 ° C. to 99 ° C.) and the film was stretched to approximately 4 × at these temperatures. “Film stretched to 4x” means, for example, that a 1 m long film is stretched until the resulting length is 4 m. Each of the two skin layers comprised approximately 2.25% of the total film weight. As a result, the core layer represented approximately 95.5% of the weight of the film. After stretching and before being thermally bonded to the nonwoven web, the film was shrunk 20% without additional heat. The final film basis weight was approximately 21 grams per square meter (gsm) and the actual thickness of the resulting film was approximately 20 microns. See FIG. 6 for the micrograph of this example.

The nonwoven web was composed of 0.4 osy spunbond, 0.8 osy spunbond / meltblown / spunbond (SMS) nonwoven web and surfactant. Spunbond having a basis weight of about 14 gsm is formed from about 1.8 denier filaments extruded from a copolymer of ethylene and 3.5% propylene (resin 6D43 available from Union Carbide), which is heated It was a point bond. The SMS fabric has a basis weight of 0.8 osy, 0.29 osy spunbond outer layer from a suitable polypropylene resin such as Montell PF304, and 0.22 from a suitable polypropylene resin such as Exxon 3746G. It consisted of a meltblown center layer. After the spunbond and meltblown layers have been hot spot bonded, the SMS laminate is dipped into a Gemtex SM-33 surfactant and water bath and then dried to yield about 1% by weight of Gemtex SM-33. Added on the nonwoven.
The stretched film and nonwoven web are then heated together at a calendar temperature of 245 degrees Fahrenheit (118 ° C) for the pattern roll and 260 degrees Fahrenheit (127 ° C) for the anvil roll at a rotational speed of 800 FPM (244 meters per minute). Combined.

Example 2
The laminate of Example 2 was made in the same manner as Example 1 except that the composition of the skin layer included 96% CATALLOY KS-084P polymer from Basell USA.
Example 3
The laminate of Example 3 was made in the same manner as Example 1 except that the film core layer was made using 35% Supercoat and approximately 62% Dow 3310. The resulting film was measured to have a basis weight of approximately 17.3 gsm and an actual film thickness of about 19 microns. See FIG. 7 for the micrograph of this example.
Example 4
Laminate films are available from Dow Chemical Co. Contains approximately 42% by weight of Dow 3310, a trace amount and type of antioxidant similar to that described in Example 1, and 58% CaCO ₃ similar to that described in Example 1. It was composed of a core layer. Two outer or skin layers on either side of the core layer are available from Basell USA Inc. It was composed of 6 percent KS084P CATALLOY® polymer from (Wilmington, Delaware). No diatomaceous earth or other anti-slip agent or filler was added to the skin layer material. The three layer film was extruded using a cast extruder of the type described to give an unstretched film having a thickness of approximately 51 microns (2 mils). The film was wound on a roll and later fed through a machine direction stretcher (MDO). The stretch roll of the MDO unit was progressively heated from approximately 150 ° F. to 210 ° F. (from 66 ° C. to 99 ° C.). The film was stretched to approximately 4x at these temperatures. Each of the two skin layers comprised approximately 3% of the total film weight. As a result, the core layer represented approximately 94% of the weight of the film. After stretching and before heat bonding to the nonwoven web, the film was shrunk 10% without additional heat. The final film basis weight was approximately 23.1 gsm, and the actual thickness of the resulting film was measured to be approximately 23 microns.

The nonwoven material of Example 1 was thermally bonded to the film using the same calender roll as in Example 1, which consisted of a 230 degree Fahrenheit (110 ° C.) pattern roll and a 180 degree Fahrenheit (82 ° C) smooth roll and a bonding rate of 330 FPM.
The resulting laminate properties were measured using a hydraulic head pressure test and a peel test. Due to the time delay specified in the ASTM 1670 test method, the barrier properties of the laminate were evaluated by the hydraulic head pressure test. A value of at least 300 mbar was chosen as the value for pre-sorting samples for subsequent tests using the ASTM 1670 procedure. (Samples with a hydraulic head pressure test value below 300 mbar tend to fail the ASTM 1670 test.) The laminate of this comparative example does not consistently achieve the desired 300 mbar value. The peel test evaluated the strength of thermally bonding the surfactant treated 0.8 osy SMS to the film. The results are recorded in Table 1.

Example 5
The film was made of the same material as Example 4 and stretched and bonded as described in Example 4 with the difference that it had an elongation of 3.4x and a shrinkage of 18%. The laminate properties from the peel test and the water head pressure test are recorded in Tables 1 and 2, respectively. The laminate of this example consistently achieved a water head pressure value of 300 mbar or greater. The peel value evaluating the thermal bond between the film and the surfactant treated nonwoven is quite large. Since the film is stretched less and shrinks more, the resulting film was measured to have a basis weight of approximately 29.7 gsm and an actual film thickness of approximately 25 microns. This greater thickness is believed to be the reason for the difference in water head pressure value and peel value.
Example 6
The film for Example 6 and the resulting laminate are the same as Example 4 except that the skin layer constitutes 12% of the weight of the film. Since the peel value is similar to Comparative Examples 3 and 7, it is estimated that an excess amount of polymer in the skin layer is required to promote acceptable attachment of the hydrophilic nonwoven. A conclusion is made. The WVTR value was not determined in this example. The resulting film was measured to have a basis weight of approximately 20.2 gsm and an actual film thickness of about 23 microns.

Comparative Example 1
This laminate consisted of 1.0 osy hydrophilic spunbond laminated by heat to a multilayer film containing no filler. The hydrophilic spunbond was made according to a method illustrating that a hydrophilic chemical additive is added to the polymer melt, as described in US Pat. No. 5,901,706. The hydrophilic chemical additive was MASIL® SF-19, a surfactant product from PPG Industries. The multilayer film consisted of a 0.6 mil film with two skin layers each contributing 30% of the weight to the film composition. Each skin layer consists of 65% CATALLOY® polymer 71-1, 25% Exxon's 3445, 5% low density polyethylene (Quantum Chemical's NA334), 5% TiO ₂ concentrate ( Ampacet 110210, 50/50 blend in polypropylene). The core layer consists of 25% CATALLOY® polymer 71-1, 30% Exxon's 3445, 5% low density polyethylene (Quantum Chemical's NA334), and 40% TiO ₂ concentrate. It was formed. The film was stretched to 1.5 × at a temperature of about 140 ° F. to 160 ° F. (from 60 ° C. to 71 ° C.). The resulting film was measured to have a basis weight of approximately 15.4 gsm and an actual film thickness of about 10 microns. See FIG. 8 for the micrograph of this example.

The nonwoven web and film consist of a heated steel calender roll consisting of a pattern roll having a measured temperature of 174 degrees Fahrenheit (79 ° C.) and a smooth roll having a measured temperature of 146 degrees Fahrenheit (63 ° C.) at 25 FPM ( 7.6 meters per minute) and were thermally coupled together. The nonwoven material contacted the pattern roll and the film contacted the anvil roll.
The calculated effective thickness for this film is advantageously compared to the actual measured thickness, as shown in Table 3, with a difference of 14%. This difference contributes to the variability in the individual measured basis weight values of the film specimens used to determine the average GSM value. This difference is the effective thickness value for each of the other examples (Example 1, Example 3 to Example 6, Comparative Example 2, and possibly Example 2). And at least half of the 31% or greater difference determined between the actual thickness value. This distinction between the actual film thickness value and the effective film thickness value for Comparative Example 1 confirms the presence of the microporous structure for all other examples.

Comparative Example 2
This laminate is from 1.0 osy hydrophilic spunbond thermally bonded to a multilayer film containing calcium carbonate (CaCO ₃ ) similar to that used in Example 1 as a microporous filler in all film layers. It was. The hydrophilic spunbond was the same as described in Comparative Example 1. The multi-layer film is made up of 60% CaCO _{3 in} high viscosity butene-rich APAO polymer outsourced by Huntsman, 55% CaCO ₃ , both 22% Dowlex 2035LLDPE and 23% Affinity (registered) by Dow Chemical (Trademark) EG-8200LLDPE. Each skin layer constituted 10% of the weight of the film. The film was stretched to approximately 3x at temperatures from about 140 degrees Fahrenheit to about 160 degrees Fahrenheit. The resulting film was measured to have a basis weight of approximately 29.2 gsm and an actual film thickness of about 22 microns. See FIG. 9 for the micrograph of this example.
The nonwoven and film are heated together using a heated steel calender roll consisting of a pattern roll having a measurement temperature of 200 degrees Fahrenheit and a smooth roll having a measurement temperature of 170 degrees Fahrenheit at a line speed of 150 FPM. Combined. The nonwoven material contacted the pattern roll and the film contacted the anvil roll.

(Table 1)

(Table 2)

(Table 3)

  Although the invention has been described in connection with certain possible embodiments, it will be understood that the invention is not limited to such embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents that may be included within the scope and spirit of the invention as defined in the appended claims.

2 shows a portion of a cross section of an embodiment of a laminate of the present invention. 2 shows a portion of a cross section of another embodiment of a laminate of the present invention. Figure 4 shows a part of a cross section of yet another embodiment of a laminate of the present invention. Figure 3 shows a part of the cross section of yet another embodiment of a laminate of the present invention. FIG. 5 illustrates one possible process for forming the multilayer film shown in FIGS. 3 and 4. FIG. The micrograph of the various examples of a film cross section is shown. The micrograph of the various examples of a film cross section is shown. The micrograph of the various examples of a film cross section is shown. The micrograph of the various examples of a film cross section is shown.

Claims (48)

A nonwoven web treated with a surfactant;
A film comprising a core layer and at least one skin layer;
The core layer contains a weight percentage of micropore-forming filler, and the film is stretched in at least one direction to a percentage of the original dimensions to be microporous, and the surfactant Thermally bonded to the treated nonwoven,
The laminate is a breathable barrier according to ASTM F1670-95.   The core layer includes from about 30% to about 75% by weight polyolefin resin and from about 70% to about 25% by weight filler having an average dimension of less than about 10 microns, the skin layer comprising: The laminate according to claim 1, comprising a CATALLOY polymer.   The laminate of claim 1, wherein the core layer comprises about 35% to about 75% by weight polyolefin resin and about 65% to about 25% by weight filler.   The laminate of claim 1, wherein the surfactant treated nonwoven web comprises spunbond polyolefin.   The laminate of claim 1, wherein the surfactant treated nonwoven web comprises a spunbond of any of polypropylene, polyethylene, a copolymer of polypropylene, and a copolymer of polyethylene.   The laminate of claim 1 wherein the surfactant treated nonwoven web comprises at least one layer of meltblown polyolefin and at least one layer of spunbond polyolefin. The laminate of claim 1, wherein the stretchable film laminate filler comprises CaCO ₃ .   The laminate of claim 1, wherein the laminate tested according to NFPA 702-1980 meets a flame propagation standard of 20 seconds or greater for Class 1 materials.   The laminate of claim 1 comprising a surgical drape. The laminate, laminate according to claim 1, characterized in that it has a water vapor transmission rate of at least about 300g / m ^2/24 hours.   The laminate according to claim 1, wherein the core layer is sandwiched between a first skin layer and a second skin layer.   The laminate according to claim 1, wherein the skin layer contains a proportion of ethylene vinyl acetate.   The laminate according to claim 1, wherein the core layer contains linear low-density polyethylene made of metallocene.   The laminate according to claim 1, wherein the core layer contains linear low density polyethylene.   The laminate according to claim 1, wherein the skin layer contains a CATALLOY polymer.   A breathable laminate according to ASTM F1670-95, comprising a nonwoven web treated with a surfactant and thermally bonded to the multilayer polyolefin resin film at a plurality of bond points, wherein at least one layer of the multilayer film further comprises A breathable laminate characterized by comprising a proportion of microporous filler by weight.   At least one layer of the multilayer film includes from about 30% to about 75% by weight polyolefin resin and from about 70% to about 25% filler by weight having an average size of less than about 10 microns, and at least The breathable laminate of claim 16, wherein one other layer comprises a CATALLOY polymer.   The at least one layer of the multilayer film comprises from about 35% to about 75% by weight polyolefin resin and from about 65% to about 25% by weight filler. Breathable laminate.   The breathable laminate according to claim 16, wherein the surfactant-treated nonwoven web comprises spunbond polyolefin.   The breathable laminate of claim 16, wherein the surfactant treated nonwoven web comprises a spunbond of any of polypropylene, polyethylene, a copolymer of polypropylene, and a copolymer of polyethylene.   17. The breathable laminate of claim 16, wherein the surfactant treated nonwoven web comprises at least one layer of meltblown polyolefin and at least one layer of spunbond polyolefin. The breathable laminate according to claim 16, wherein the stretchable film laminate filler comprises CaCO ₃ .   The breathable laminate of claim 16, comprising a surgical drape. The laminate is breathable laminate of claim 16, characterized in that it comprises a water vapor transmission rate of at least about 300g / m ^2/24 hours.   The breathable laminate according to claim 16, wherein at least one layer of the multilayer film contains a proportion of ethylene vinyl acetate.   The breathable laminate according to claim 16, wherein at least one layer of the multilayer film contains a linear low density polyethylene of metallocene.   The breathable laminate of claim 16, wherein at least one layer of the multilayer film comprises linear low density polyethylene.   The breathable laminate according to claim 16, wherein at least some of the bonding points form a bonding attachment between the web and the multilayer film. A method of forming a laminate according to ASTM F1670-95, comprising:
Treating the nonwoven web with a surfactant,
Heating a multilayer film having at least one layer comprising a microporous filler;
Stretching the multilayer film to an unstretched proportion during the heating stage;
Thermally bonding the multilayer film to the surfactant treated nonwoven web;
Including methods.   30. The method of claim 29, further comprising shrinking the multilayer film by a small percentage prior to bonding the film to the nonwoven web.   At least one layer of the multilayer film includes from about 30% to about 75% by weight polyolefin resin and from about 70% to about 25% filler by weight having an average dimension of less than about 10 microns. 30. The method of claim 29, wherein:   30. The method of claim 29, further comprising a CATALLOY polymer for at least one layer of the multilayer film.   30. The method of claim 29, further comprising bonding a second nonwoven web to the laminate such that the multilayer film is disposed between the two nonwoven webs.   30. The method of claim 29, wherein the multilayer film is maintained at a temperature between about 160 degrees Fahrenheit and about 220 degrees Fahrenheit with the film stretched.   32. The method of claim 30, wherein the multilayer film is maintained at a temperature between about 160 degrees Fahrenheit and about 220 degrees Fahrenheit with the film contracted.   30. The method of claim 29, wherein the multilayer film is stretched to at least about 200% of its original length.   30. The method of claim 29, wherein the multilayer film is stretched between about 250% to about 500% of its original length.   30. The method of claim 29, wherein the multilayer film is stretched to at least about 300% of its original length.   30. The method of claim 29, wherein the laminate tested according to NFPA 702-1980 meets a flame propagation standard for Class 1 materials of 20 seconds or greater. A method of forming a laminate according to ASTM F1670-95, comprising:
Treating at least one surface of the nonwoven web with a surfactant;
Forming an outer layer from the treated nonwoven web;
Heating a multilayer film having at least one layer comprising a microporous filler and at least one skin layer;
Stretching the multilayer film to at least 200% of the unstretched state with heat applied to the film;
Layering the multilayer film on the treated nonwoven web such that the skin layer contacts the surfactant treated surface;
Thermally bonding the film to the surfactant treated surface;
A method involving that.   41. The method of claim 40, further comprising shrinking the multilayer film by a small percentage prior to bonding the film to the nonwoven web.   41. The method of claim 40, further comprising shrinking the multilayer film by about 20% of the final stretched state.   41. The method of claim 40, wherein the laminate tested according to NFPA 702-1980 meets a flame propagation standard for Class 1 materials of 20 seconds or greater.   41. The method of claim 40, wherein the surfactant is coated on the surface of the nonwoven web.   41. The method of claim 40, wherein the film is maintained at a temperature between about 160 degrees Fahrenheit and about 220 degrees Fahrenheit with the film stretched.   14. The method of claim 13, wherein the film is maintained at a temperature between about 160 degrees Fahrenheit and about 220 degrees Fahrenheit with the film deflated.   41. A method according to claim 40, which relates to the production of a surgical drape. 41. The method of claim 40, wherein the water vapor transmission rate test (WVTR) as measured by test method ASTM standard E96-80 gives a value greater than about 300 g / m < ² > / day.

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