Patent Application
20210196008
The present application relates to webs having precursors for producing mechanical fasteners, to tools for making precursors and precursor webs, and to mechanical fasteners made from the precursors and webs containing the fasteners. The mechanical fasteners are suitable for use in releasable closure systems, for example, but not limited to fastener systems for diapers.
Releasable closure systems, also called ‘hook and loop fasteners’ include a plurality of closely spaced upstanding projections with loop-engaging heads, also called ‘hook members’. The hook members can releasably engage with woven, nonwoven, or knitted loops, the corresponding ‘loop members’ . Mechanical fastener systems are used to provide releasable attachments in numerous applications, in particular fastener systems for disposable absorbent articles like diapers, napkins etc. Hook structures of various shapes can be made from thermoplastic materials by molding, for example as described in U.S. Pat. No. 3,594,865. Alternatively, hook members may be formed from precursors. The precursors are also formed by molding of a thermoplastic resin yielding a web containing a plurality of precursors on a backing. The web is then subjecting to a capping step where the precursors are shaped into hooks, resulting in a plurality of fasteners on the backing. Such methods are described, for example, in international patent application Nos. WO 94/23610 and 92/04839. Other technologies for making mechanical fasteners are described, for example, in US 7,198,743 B2.
There is a need for providing webs of fasteners on thin backings because such webs are mechanically more flexible and light weight. In WO2013/040156 hook members are described on thin backings. The hook members are prepared from precursors by capping. The backing was then thinned in a subsequent stretching step. Stretching, however, is an additional process step and may also lead to mechanical tensions in the backing and to a lower area density of the fasteners, which may not always be desired.
There is a need for alternative methods for making mechanical fastener webs. Advantageously such methods allow to produce fasteners of various shapes without requiring thick backings.
In the following there are provided webs containing precursors that have a greater base width than height. The precursors can be removed from the molds using little force and the precursors webs can have a thin backing layer. The precursors can be converted into mechanical fasteners.
In the following there is provided a web (10) of precursors (18) for mechanical fasteners (48), the web (10) comprising at least one backing layer (30) and a plurality of upstanding precursors (18) for mechanical fasteners arranged on the backing layer (30) and integral with the backing layer (30), wherein each precursor (18) of the plurality of precursors has a distal end (12) and a proximal end (16) by which the precursor (18) is connected to the backing layer (30), and wherein the base width (22) at the proximal end (16) of the precursor is greater than the height (24) of the precursor (18), and wherein the precursors (18) either have a constant width towards their distal ends (12) or taper towards their distal ends (12), and wherein the backing layer (30) has a thickness (32) of from about 10 μm to about 75 μm.
In another aspect there is provided a tool (80) for making the web (10) wherein the tool (80) comprises a mold surface (79) having a plurality of cavities (78) having the inverse shape of the precursors (18).
In a further aspect there is provided a method of making the tool (80) comprising depositing material on a surface or removing material from a surface or both to create a plurality of cavities (78) having the inverse shape of the precursors (18) to provide a mold surface (79).
In yet another aspect there is provided a method of making the web (10) comprising
In another aspect there is provided a web (40) of mechanical fasteners comprising at least one backing layer (30) and a plurality of upstanding mechanical fasteners (48) arranged on the backing layer (30) and integral with the backing layer (30), wherein each of the mechanical fasteners (48) of that plurality has (i) head portion (42) comprising the distal end (44) of the fastener (48) and (ii) a stem portion linking the head portion (42) of the fastener (48) with the backing layer (30) and comprising the proximal end (50) by which the fastener (48) is linked with the backing layer (30), wherein the stem portion is tapered and the width (52) of the head portion (42) is greater than the width (58) of the stem immediately underneath the head portion (42) such that the head portion (42) forms an overhang and wherein the width (52) of the head portion (42) is equal or less than the base width (54) of the fastener (48) at the proximal end (50) and wherein the base width (54) is greater than their height (26) of the fastener (48), and wherein the thickness (32) of the backing layer (30) is from about 10 μm up to about 75 μm.
In a further aspect there is provided a method of making the web (40) of fasteners comprising
In yet another aspect there is provided an absorbent article (100) comprising the web (40) of fasteners.
In a further aspect there is provided a method of making an absorbent article (100) comprising (i) providing an absorbent article, (ii) connecting the web (40) of fasteners to the absorbent article (100).
The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings, in which:
It is understood that the drawings and the following detailed description are for illustrative purposes only and should not be read in a manner that would unduly limit the scope of this disclosure. Reference will now be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Features illustrated or described as part of one embodiment can used with other embodiments to yield still a further embodiment. It is intended that the present disclosure include these and other modifications and variations.
Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Contrary to the use of “consisting”, the use of “including,” “containing”, “comprising,” or “having” and variations thereof is meant to encompass the items listed thereafter as well as additional items. The use of “a” or “an” is meant to encompass “one or more”. Any numerical range recited herein is intended to include all values from the lower value to the upper value of that range and including the end points of the range. For example, a concentration range of from 1% to 50% is intended to be an abbreviation and to expressly disclose the values 1% and 50% and the values between the 1% and 50%, such as, for example, 2%, 40%, 10%, 30%, 1.5%, 3.9% and so forth. Reference numerals are used for illustration only.
In this disclosure webs of precursors are provided. The webs of precursors according to the present disclosure contain a plurality of upstanding posts arranged on a backing layer. The posts are rather flat but rather wide. Due to that shape the precursors can be easily removed from molds and therefore can be obtained on thin backings. Mechanical fasteners on thin backings can be prepared from these precursors, by shaping the precursors to provide a loop-engaging head region, for example by creating an overhang in the head region, for example by capping. Therefore, webs of fasteners on thin backings can be obtained from the web of precursors without requiring stretching steps - although stretching may still be done. The fasteners resulting from the precursors have low height and small head regions but still have similar shear and peel strength behavior than commercial fasteners.
Therefore, the posts are referred to herein also as “precursors” or “precursors for mechanical fasteners”.
The plurality of precursors will now be described in greater detail by referring to
The precursor (18) comprises a head portion that includes the distal end (12) of the precursor. The precursor also has a base portion that includes the proximal end (16) of the precursor. The head portion may begin at the distal end (12) and continues towards the proximal end (16). It may form from 1% to about 50% of the height of the precursor above the backing. The base portion starts with the proximal end (16) and extends towards the distal end (12) of the precursor. It may comprise up to 50% of the height of the precursor. Between head portion and base portion there may be one or more than one middle portions.
The height (24) of the precursors is the height of the posts above the backing layer (30), i.e. the distance between the distal end (12) and the proximal end (16) of the precursors (18) as is illustrated in
For the purpose of this disclosure, all dimensions of the upstanding precursors or fasteners and backing layers described herein are measured by optical microscopy.
The precursors have a width at their base (base width) that is greater than their height (24). The base width (22) is the width measured at the proximal end (16). The term “width” should be understood to include the diameter of the post (18) with a circular cross-section. When the post has more than one width dimension (e.g. when the post (18) is of rectangular or elliptical shape, the term “width” refers to the largest width dimension, e.g. the largest axis or diameter—as illustrated in
The precursors (18) may have a variety of cross-sectional shapes. For example, the cross-sectional shape of the post may be a polygon (e.g., square, rectangle, hexagon, or pentagon), which may be a regular polygon or not, or the cross-sectional shape of the post may be curved (e.g., round or elliptical). The precursors (18) may have a symmetric or non-symmetric shape. For example, when viewed from the top (illustrated in
It is an advantage of the precursors according to the present disclosure that due to their shape they can be demolded easily and requiring only little force. This means thinner resin layers may be used when demolding the precursors and therefore the resulting webs can have precursors arranged on a thin backing layer. The backing layer (30) on which the precursors (18) are arranged can have a thickness (32) of 75 μm or less. Preferably, the backing layer (30) has a thickness (32) from about 10 μm up to about 75 μm, preferably from about 15 μm up to about 70 μm, more preferably from about 21 μm up to about 65 μm, or from about 21 μm up to about 50 μm. In one embodiment, the backing layer (30) has a thickness (32) from about 10 μm up to about 19 μm. A low thickness of the backing layer, or the web, is useful for saving raw materials. Additionally, backing layers or webs of small thickness have an increased mechanical flexibility and are of lower weight. For example, webs with thin backing layers can be easier wound up into rolls and can be transported more easily because they have a reduced weight. Moreover, increased flexibility helps to provide for a good fit of the web on the articles to which they are to be applied.
In the precursors for mechanical fasteners according to the present disclosure the backing layer and the upstanding posts are typically integral (that is, formed at the same time as a unit, unitary). In some embodiments, the backing layer and the precursors are made from the same thermoplastic material. The thermoplastic backing is typically in the form of a sheet or web that may have an essentially uniform thickness with the upstanding precursors directly attached to the thermoplastic backing. Upstanding posts on a backing can be made, for example, by conventional extrusion through a die and cast molding techniques as illustrated in
Suitable tool rolls (80) can be made, for example, by forming (e.g., by computer numerical control with drilling, photo etching, using galvanic printed sleeves, laser drilling, electron beam drilling, metal punching, direct machining, or lost wax processing) a series of holes having the inverse shape of the upstanding posts into the cylindrical face of a metal mold or sleeve. Other suitable tool rolls include those formed from a series of plates defining a plurality of post-forming cavities about its periphery such as those described, for example, in U.S. Pat. No. 4,775,310 (Fischer). Cavities may be formed in the plates by drilling or photoresist technology, for example. Still other suitable tool rolls may include wire-wrapped rolls, which are disclosed along with their method of manufacturing, for example, in U.S. Pat. No. 6,190,594 (Gorman et al.). The exposed surface of the mold, sleeve, plate, or wire may be coated to impart surface properties such as increased wear resistance, controlled release characteristics, and controlled surface roughness. The coating, if present, is preferably selected so that the adhesion of the thermoplastic material to the tool roll is less than the cohesion of the thermoplastic material at the time of the removal of the thermoplastic backing from the tool roll.
Another exemplary method for forming a thermoplastic backing with upstanding posts includes using a flexible mold belt defining an array of upstanding post-shaped cavities as described in U.S. Pat. No. 7,214,334 (Jens et al.). The mold belt is trained about first and second rolls, and a source of molten thermoplastic material is arranged to deliver the thermoplastic to the mold belt. The apparatus is constructed to force the plastic resin into the upstanding post-shaped cavities of the belt under pressure in a gap to mold the array of upstanding posts while forming the thermoplastic web layer.
Many thermoplastic materials are useful for precursors of mechanical fasteners according to the present disclosure. Suitable thermoplastic materials for the thermoplastic backing with upstanding elements include polyolefin homopolymers such as polyethylene and polypropylene, copolymers of ethylene, propylene and/or butylene; copolymers containing ethylene such as ethylene vinyl acetate and ethylene acrylic acid; polyesters such as poly(ethylene terephthalate), polyethylene butyrate and polyethylene napthalate; polyamides such as poly(hexamethylene adipamide); polyurethanes; polycarbonates; poly(vinyl alcohol); ketones such as polyetheretherketone; polyphenylene sulfide; poly(acrylonitrile-butadiene-styrene); plasticized polyvinylchlorides; and mixtures thereof Typically, the thermoplastic is a polyolefin (e.g., polyethylene, polypropylene, polybutylene, ethylene copolymers, propylene copolymers, butylene copolymers, and copolymers and blends of these materials). The various thermoplastic materials described above can be formulated into a master batch having a desired property (e.g., color); however, the presence or absence of dyes, pigments, or other colorants are not essential to this disclosure. Suitable thermoplastic materials that allow good filling of small-sized cavities have typically a low viscosity (e.g. a polypropylene with a melt flow rate of 25 g/10 min or higher). Suitable thermoplastic materials that allow fast solidification of the melt after filling of the cavities and by such resulting in a short time for deforming, contain typically small amounts of additives the increase rate of crystallization of the polymer (e.g. nucleating agents).
In some embodiments, the thermoplastic backing with upstanding elements can be made from a multilayer or multi-component melt stream of thermoplastic materials. This can result in elements formed at least partially from a different thermoplastic material than the one predominately forming the backing. A multilayer or multi-component melt stream can be formed by any conventional method. A multilayer melt stream can be formed by a multilayer feedblock, such as that shown in U.S. Pat. No. 4,839,131 (Cloeren). A multicomponent melt stream having domains or regions with different components could also be used. Useful multicomponent melt streams could be formed by use of inclusion co-extrusion die or other known methods (e.g., that shown in U.S. Pat. No. 6,767,492 (Norquist et al.).
In one aspect the present disclosure also refers to a tool for making a web containing the precursors as described herein. The tool has a surface containing a plurality of cavities shaped as negatives of the plurality of precursors according to the present disclosure. Presursors of shape and dimensions as described herein can be obtained by filling a moldable resin, typically in flowable form into the cavities. The resin is then allowed to solidify in the cavities, for example by cooling, or by curing it into a solid form. Removing the resin from the cavities yields the precursors. If the resin is filled in the cavities and also over the mold surface a web containing the cavities is obtained after stripping off the resin from the cavities and the mold surface. By controlling the thickness of the resin layer on the mold surface the thickness of the resulting backing layer (30) can be controlled. The thickness can be low and stretching of the resulting web to obtain thinner backings may be carried out but is not necessary.
The tool may be a cylinder having the cavities on its surface. Alternatively, the mold can contain several parts which may be attachable or can be removed from each other, for example the surface of the mold containing the cavities may be mounted on a carrier and removed from the carrier. Molds, or mold surfaces containing the cavities can be made by removing materials from a surface (etching, cutting, milling, drilling) or by method adding material (electro-plating) to create the desired cavities. Techniques known in the art may be used. Such methods may involve forming the required cavities by chemical etching, electro-plating, laser-etching or e-drilling as described, for example, in US patents Nos 5,900,350 and 6,289,766.
The precursors formed upon exiting the cavities of the mold typically do not have loop-engaging head regions, for example caps, but they can be subsequently formed in a subsequent shaping step, for example, as illustrated in
In some embodiments, distal caps of the upstanding fastening elements are reshaped after they are formed. For example, passing a thermoplastic backing having upstanding capped posts through a gapped nip of a heated rubber roll and a backup roll causes the overhanging portions of the distal cap, that extend beyond the post, to be pushed down toward the backing. This process is described in U.S. Pat. No. 6,132,660 (Kampfer).
In addition to the continuous methods described above, it is also envisioned that thermoplastic backings having upstanding fastening elements can be prepared using batch processes (e.g., single piece injection molding). The thermoplastic backing may have any suitable dimension, but length (L) and width (W) dimensions of at least 10 centimeters may be useful.
The present disclosure also provides fastener webs, i.e. webs containing a plurality of upstanding posts arranged on a backing layer of the web wherein the posts contain a loop-engaging head region. The webs of fasteners can be obtained by subjecting the precursors described above to a shaping step where the head regions of the precursors are formed into loop-engaging structures, for example by capping.
The plurality of the fasteners will now be described in greater detail by referring to
The fasteners of the present disclosure may have a height (26) that is smaller than the height of the precursors from which they originate, for example due to the capping. Typically, the fasteners have a height of from about 90 μm to about 900 μm, preferably from about 180 μm to about 360 μm. The height (26) of the fasteners is the height of the fasteners above the backing, i.e. the maximum distance between the distal end (44) and the proximal end (50) of the fasteners (48) as illustrated in
The width at the base (base width, (54)) of the fasteners (48) is greater than their height (26). The fasteners typically have the same width at their base as their precursors. They may have a width at their base of from about 105 μm to about 1010 μm, preferably from about 220 μm to about 900 μm, more preferably from 300 μm to about 600 μm. Like the precursors the term “width” should be understood to include the diameter of the stem with a circular cross-section. When the post has more than one width dimension (e.g. when the stem is of rectangular or elliptical shape, the term “width” refers to the largest width dimension, e.g. the largest axis or diameter—as illustrated in
The stems may have a variety of shapes. For example, the shape of the stems may be a polygon (e.g., square, rectangle, hexagon, or pentagon), which may be a regular polygon or not, or the cross-sectional shape of the stems may be curved (e.g., round or elliptical).
Typically, the stems taper and decrease in width from their proximal ends toward their distal ends (as illustrated in
In other embodiments the stems are tapered but the width of the stems decreases discontinuously, for example in discrete intervals interrupted by at least one interval where the width remains constant. Typically, the base width (50) of the fasteners (48) is greater than the width (58) immediately underneath their heads (42). The width (58) immediately underneath the heads (42) may be from about 100 μm to about 1000 μm, provided that the width is smaller than the width at the base (54). Suitable ratios of width at the base (54) to width (58) immediately underneath the heads (42) include ratios from about 5 to 1 to about 1.1 to 1, preferably from about 2.5 to 1 to about 1.5 to 1.
Generally, the heads (42) of the upstanding fastening elements (48) have a shape that is different from their precursors. The heads (42) typically protrude over the immediately underlying portion of the stem (58), i.e. the heads have at least one overhang. For example, the fastening element (48) may be in the cross-sectional shape of a mushroom (e.g., with a circular or oval head enlarged with respect to the underlying part of the stem), a nail, or a T. In some of these embodiments, the overhang of the heads extends beyond the immediately underlying part of the stem on at least two opposing sides. Preferably, the heads (42) have an overhang on each side of the stem (58). The extent of overhang on the two opposing sides may or may not be equal. In some of these embodiments, the fastener (48) is in the shape of a mushroom (e.g., with a circular or oval head enlarged with respect to the immediately underlying stem) or a nail. In preferred embodiments at least a portion of the overhang is in all directions although the amount of overhang may not be equal in all directions. In some embodiments the overhang extends up to 90 μm beyond the stem immediately underneath the head (42) in at least one direction. In other embodiments, the overhang is up to 85 μm, 80 μm or 75 μm. The minimum overhang may be selected, for example, based on the fiber diameter of the loop that is selected to engage with the mechanical fastener disclosed herein. In some embodiments, the overhang is at least 5 μm or at least 10 μm. The overhang may be in the range, for example, from 5 μm to 85 μm, or from 5 μm to 65 μm.
The overhang in the upstanding fastening elements disclosed herein is typically considered to be loop-engaging. The term “loop-engaging” as used herein relates to the ability of an upstanding fastening element to be mechanically attached to a loop material.
For creating an overhang the width (52) of the heads (42) of the fasteners (48) is greater than the width (58) of the stems directly underlying the heads. Since the stems are tapered, the width (58) of the stems directly underlying the head is also smaller than the width at the base (54). As illustrated in
The heads (42) can have various shapes and may be symmetric or non-symmetric. For example, when viewed from the top (illustrated in
Typically, the fasteners elements are obtained by providing the web of precursors to a shaping step to give the head region of the precursors a loop-engaging shape. Typically, the web or the backing layer and the base portion of the precursors may not be affected by the shaping step taken to convert the web of precursors into a web of fasteners. Therefore, the web of fasteners has a backing layer (30) as described above with respect to the precursors. Typically, the backing layer (30) of the web (40) of fasteners has a thickness (32) of 75 μm or less. Preferably, the backing layer has a thickness (32) between 10 μm to 75 μm, preferably from about 15 μm to about 70 μm, more preferably from about 21 μm up to about 65 μm, or from 21 μm to 50 μm. In one embodiment the backing layer (30) has a thickness (32) of from about 10 μm to 19 μm. In the mechanical fasteners according to the present disclosure the backing layer and the upstanding posts are typically integral (that is, formed at the same time as a unit, unitary). In some embodiments, the backing layer and the stems of the fasteners or the fasteners are made from the same thermoplastic material. The thermoplastic material typically is the same as described above for the precursors.
The web of fasteners may contain additional layers, as will be described below with respect to fastening laminates.
The web (40) of fasteners according to the present disclosure may be wound up into a roll for storage and transportation. An advantage of the webs according to the present disclosure is that webs can have very thin backings and are therefore of lower weight and can be easier stored, transported or processed.
For any of the embodiments of the mechanical fastener according to the present disclosure, the thermoplastic backing may be in the form of a roll, from which mechanical fastener patches containing a plurality of fasteners, for example, may be cut in a size appropriate to the desired application. In this application, the thermoplastic backing may also be a patch that has been cut to a desired size. In some of these embodiments, the second surface of the thermoplastic backing (i.e., the surface opposite the first surface from which the upstanding fastening elements project) may be coated with an adhesive (e.g., a pressure sensitive adhesive). In such embodiments, when the thermoplastic backing is in the form of a roll, a release liner may be applied to the exposed adhesive.
Fastening laminates that can be formed after joining the thermoplastic backing layer to a carrier may be useful, for example, in disposable absorbent articles. The fastening laminate may be in the form of a fastening tab that is bonded to at least one of the front waist region or the rear waist region extending outwardly from at least one of the left longitudinal edge or the right longitudinal edge of the absorbent article. In other embodiments, the fastening laminate may be an integral ear portion of the absorbent article.
In some embodiments of the mechanical fastener disclosed herein, the thermoplastic backing is not joined to a carrier, at least when it is initially formed. In other embodiments, the second surface of the thermoplastic backing (i.e., the surface opposite the first surface from which the upstanding fastening elements project) is joined to a carrier. The thermoplastic backing may be joined to a carrier, for example, by lamination (e.g., extrusion lamination), adhesives (e.g., pressure sensitive adhesives), or other bonding methods (e.g., ultrasonic bonding, compression bonding, or surface bonding). The thermoplastic backing may also be joined to a carrier during the formation of the thermoplastic backing with upstanding posts. The resulting article may be a fastening laminate, for example, a fastening tab joined to the back sheet of an absorbent article useful for joining the front waist region and the rear waist region of an absorbent article. The carrier, which in some embodiments may be joined to the second surface of the thermoplastic backing, may be continuous (i.e., without any through-penetrating holes) or discontinuous (e.g. comprising through-penetrating perforations or pores). The carrier may comprise a variety of suitable materials including woven webs, non-woven webs (e.g., spunbond webs, spunlaced webs, airlaid webs, meltblown web, and bonded carded webs), textiles, plastic films (e.g., single- or multilayered films, coextruded films, or films comprising foam layers), and combinations thereof. In some embodiments, the carrier is a fibrous material (e.g., a woven, nonwoven, or knit material). The term “nonwoven” when referring to a carrier or web means having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs can be formed from various processes such as melt blowing processes, spunbonding processes, spunlacing processes, and bonded carded web processes. In some embodiments, the carrier comprises multiple layers of nonwoven materials with, for example, at least one layer of a meltblown nonwoven and at least one layer of a spunbonded nonwoven, or any other suitable combination of nonwoven materials. Or, the carrier may be a composite web comprising a nonwoven layer and a dense film layer.
Fibrous materials that provide useful carriers may be made of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., thermoplastic fibers), or a combination of natural and synthetic fibers. Exemplary materials for forming thermoplastic fibers include polyolefins (e.g., polyethylene, polypropylene, polybutylene, ethylene copolymers, propylene copolymers, butylene copolymers, and copolymers and blends of these polymers), polyesters, and polyamides. The fibers may also be multi- component fibers, for example, having a core of one thermoplastic material and a sheath of another thermoplastic material.
One or more zones of the carrier may comprise one or more elastically extensible materials extending in at least one direction when a force is applied and returning to approximately their original dimension after the force is removed. The term “elastic” refers to any material that exhibits recovery from stretching or deformation. Likewise, “nonelastic” materials, which do not exhibit recovery from stretching or deformation, may be useful for the carrier as well.
Mechanical fasteners according to the present disclosure are useful components in fastening systems that include the mechanical fastener according to any of the above embodiments and a loop material. Although mechanical fasteners according to the present disclosure are useful with a variety of different loop materials, in some embodiments, the loop material is a low-loft loop material, which is desirable for use in fastening systems because of their low cost and low material-usage. Examples of low-loft materials include nonwoven materials, for example, made from any of the materials described above for carriers. In some embodiments, the loop material has a fiber basis weight in a range from 10 grams per square meter (gsm) to 30 gsm. Fiber basis weight is a basis weight of just the fiber in the loop material (e.g., removed from any backing). In some embodiments, the loop material has a fiber basis weight in a range from 10 gsm to 20 gsm or from 15 gsm to 20 gsm. In some embodiments, the loop material has a fiber diameter in a range from 15 micrometers to 25.4 micrometers. The loop material may have a loop height of up to 500 μm and a loop width of up to 2500 μm. In some embodiments, the loop material has a fiber basis weight in a range from 20 grams per square meter to 30 grams per square meter, and the mechanical fastener engages with the loop material with a shear strength of at least 2000 gram-force. However, in other embodiments, mechanical fasteners may be useful with loop materials having fiber basis weights in a range from 30 gsm to 50 gsm as well.
Fastening laminates according to the present disclosure may also be useful, for example, as fastening tabs for pants-style diapers such as those described in U.S. Pat. No. 5,531,732 (Wood). In some embodiments, the absorbent article according to the present disclosure is a disposable pants-style diaper having a fibrous outer covering or back sheet that can engage with upstanding fastening elements on a fastening tab disclosed herein. The fastening tab can be located on a seam or side panel portion of the pants-style diaper such that a free end of the fastening tab is able to engage the fibrous outer covering or back sheet. The fastening tab free end is useful, for example, for adjusting the pants-style diaper's circumferential fit or size (in other words, waist fit or size) by gathering the side panel portion. The side panel portion may be free of any integrally bonded absorbent core structure in some embodiments. In some embodiments, the pants-style diaper has at least one perforation line extending from the waist opening to one of the leg openings. The perforation is generally near the side seam, may be positioned toward the front portion of the diaper, and may be parallel or non-parallel to the side seam. In some embodiments, the pants-style diaper has a pair of perforation lines, one on each side of the diaper. The perforation line(s) can either be broken before the diaper is positioned around the user's torso or while the user is wearing the diaper. The fastening tab free end can then be used to refasten the diaper so that it is snug around the user's waist. The fastening tab free end may also be useful, for example, as a disposal means when the pants-style diaper is removed from the wearer (e.g., by tearing the side panel or perforation line). The fastening tab typically remains on the side panel portion. The diaper can then be rolled into a compact form for disposal, and the fastening tab can be used to keep the diaper in a rolled form. In some embodiments, a fastening tab according to the present disclosure can be applied to a pants-style diaper in a manufacturing process by using a laminate in which separated strips of the mechanical fastener disclosed herein are laminated to a nonwoven web using any of the methods described above. In some embodiments, two strips of the mechanical fastener can be positioned on the nonwoven web with the nonwoven extending beyond the mechanical fastener strips on both sides such that there are first and second side portions and a central portion of exposed nonwoven separated by the mechanical fastener strips of the laminate. The laminate can be in the form of a roll with longitudinally extending separated mechanical fastener strips. In an efficient embodiment of the manufacturing process of a pants-style diaper, the laminate can be cut in the cross-direction to a desired width of a fastening tab and aligned with two connected diapers in a web of diaper chassis. Then, the laminate can be cut down the middle of the central portion of exposed nonwoven at or about the same time the two connected diapers are cut apart so that half the laminate is applied to one diaper and half is applied to the other diaper. Then bonding of the side seams of the diaper and bonding of the fastening tab to the side seams can be carried out simultaneously, if desired. In these embodiments, each of the first and second side portions of exposed nonwoven can advantageously serve as a fingerlift for the left and right fastening tabs of two different pants-style diapers.
The fastening laminate including the mechanical fastener disclosed herein may also be useful, for example, for absorbent articles such as sanitary napkins. A sanitary napkin typically includes a back sheet that is intended to be placed adjacent to the wearer's undergarment. The back sheet may comprise a thermoplastic backing with spaced-apart, upstanding capped posts to securely attach the sanitary napkin to the undergarment, which mechanically engages with the capped posts. The back sheet may formed with upstanding capped posts. In other embodiments, the mechanical fastener may be in the form of a strip or patch that is attached to the back sheet with adhesive or using another bonding mechanism.
In other embodiments, the mechanical fastener according to the present disclosure may be useful, for example, in absorbent pads having at least a top sheet, an absorbent core, and a back sheet, wherein the back sheet comprises the mechanical fastener. The back sheet may formed with upstanding capped posts. In other embodiments, the mechanical fastener may be in the form of a strip or patch that is attached to the back sheet with adhesive or using another bonding mechanism. The absorbent pads may be useful, for example, in adult incontinence articles, which may be in the form of an open-type diaper having the general shape such as that shown in
Fastening tabs (130) are arranged at the lateral edges of the rear waist region (125) on each side comprising mechanical fastening patches (140) having mechanical fasteners (48). A dedicated landing zone can be arranged on the outer surface of the front waist region (115); alternatively the entire backsheet (110) can comprise a nonwoven material. The surface of the front waste region (115), for example a loop material, knitted material or a non-woven material, can be engaged by the mechanical fasteners (48) of the mechanical fastening patches (140) which are arranged at the fastening tabs (130) for fastening and closing the absorbent article, respectively.
The present disclosure will now be illustrated further by way of examples and illustrative embodiments. However, there is no intention to limit the disclosure to the embodiments illustrated in the examples and the list of embodiments.
An ethylene-propylene copolymer resin was extruded through a cast film die onto a rotating mold. The mold had a staggered array of cavities, approximately 0.64 mm apart in cross direction with a density of approximately 273 cavities per square centimeter. Each of the cavities had a cross section in form of a regular hexagon that tapered from the outside surface of the roll towards the end of the cavity. The hexagonal cross section at the outside surface of the roll had a width of approximately 0.5 mm. Width dimension at the distal end of the cavity was approximately 0.2 mm. The cavity had a depth of approx. 0.23 mm. The equipment used differed from that illustrated in
Example 1: To form mechanical fasteners the precursor web was processed by a method as described in U.S. Pat. No. 5,868,987 to form non-circular caps. The resulting fasteners had a height of about 0.21 mm. The oblong cap had an extension in cross direction of approximately 0.38 mm and in machine direction of 0.30 mm.
Example 2: To form mechanical fasteners the precursor web was processed by a similar method as described in Example 1, but with a flat capping roller. The resulting fasteners had a height of approximately 0.2 mm. The capping resulted in a circular cap that had a diameter of approximately 0.33 mm.
Peel and shear properties of these fasteners were evaluated using a nonwoven backsheet. The backsheet has been removed from an adult diaper; Abri Form L2 Super produced by Abena A/S Aabenraa, Denmark.
For peel evaluation, a patch of the mechanical fastener (25 mm in the machine direction (MD) and 13 mm in the cross-direction (CD)) was attached to one end of a tape carrier. The remaining open adhesive was covered by a thin nonwoven. From the nonwoven material a patch of 50 mm in the MD and 60 mm in the CD was cut. The mechanical fastener specimen was put on the nonwoven so that in the peel test both materials were evaluated in CD orientation. For engagement of the fasteners the hook specimen was pressed onto the loop materials using one cycle (one cycle=one forward and one backward pass) with a 2000-gram roller moving at 300 mm per minute. After clamping the nonwoven loop in the lower jaw and the hook specimen in the upper jaw T-peel is tested at a separation speed of 300 mm per minute.
For the example 1 and 2 maximum peel strength were 1.4 N and 1.3 N.
For shear evaluation, a patch of the mechanical fastener (25 mm in the machine direction (MD) and 13 mm in the cross-direction (CD)) was attached to one end of a tape carrier. The remaining open adhesive was covered by a thin nonwoven. The nonwoven material (50 mm in the MD and 60 mm in the CD) was attached with double sided tape to a metal plate. The mechanical fastener specimen was put on the nonwoven so that in the shear test both materials were evaluated in CD orientation. The mechanical fastener specimen was pressed onto the nonwoven using one cycle (one cycle=one forward and one backward pass) with a 2000-gram roller moving at 300 mm per minute. After clamping the metal plate with the nonwoven loop in the lower jaw and the hook specimen in the upper jaw shear is tested at a separation speed of 300 mm per minute.
In examples 1 and 2 maximum peels were 6 N and 11 N.
These examples show that precursors with their specific broad but flat geometry can still be removed from molds even with thin backings. Hooks prepared from the precursors according to the present description have similar peel and shear force behavior than commercial hooks despite their broader and flatter geometries.
In a first embodiment, the present disclosure provides a web (10) of precursors (18) for mechanical fasteners (48), the web (10) comprising at least one backing layer (30) and a plurality of upstanding precursors (18) for mechanical fasteners arranged on the backing layer (30) and integral with the backing layer (30), wherein each precursor (18) of the plurality of precursors has a distal end (12) and a proximal end (16) by which the precursor (18) is connected to the backing layer (30), and wherein the base width (22) at the proximal end (16) of the precursor is greater than the height (24) of the precursor (18), and wherein the precursors (18) either have a constant width towards their distal ends (12) or taper towards their distal ends (12), and wherein the backing layer (30) has a thickness (32) of from about 10 μm to about 75 μm.
In a second embodiment the present disclosure provides a web (10) according to the first embodiment, wherein the backing layer (30) and the precursors (18) comprise the same thermoplastic material.
In a third embodiment, the present disclosure provides a web (10) according to either one of the first or second embodiment, wherein the precursors (18) have a height (24) of from about 100 and up to about 1000 μm.
In a fourth embodiment, the present disclosure provides a web (10) according to any one of the first to the third embodiments, wherein the precursors have a width (22) from about 105 μm and up to about 1010 μm.
In a fifth embodiment, the present disclosure provides a web (10) according to any one of the first to the fourth embodiments, wherein the precursors (18) have a ratio of base width (22) to height (24) of from about 1.1:1.0 to 10:1.
In a sixth embodiment, the web (10) according to any one of the first to the fifth embodiments wherein the backing layer (30) has a thickness of from about 10 μm and up to about 50 μm.
In a seventh embodiment, the present disclosure provides a web (10) according to any of the first to the sixth embodiments, wound up into a roll.
In an eighth embodiment, the present disclosure provides a tool (80) for making a web (10) according to any one of the first to the seventh embodiment, wherein the tool (80) comprises a mold surface (79) having a plurality of cavities (78) having the inverse shape of the precursors (18) as defined in any one of the first to the fifth embodiments.
In a ninth embodiment, the present disclosure provides a method of making a tool (80) according to the eight embodiment, comprising depositing material on a surface or removing material from a surface or both to create a plurality of cavities (78) having the inverse shape of the precursors (18) to provide a mold surface (79).
In a tenth embodiment, the present disclosure provides a method of making a web (10) according to any of the first to the seventh embodiment, the method comprising
In an eleventh embodiment, the present disclosure provides a web (40) of mechanical fasteners comprising at least one backing layer (30) and a plurality of upstanding mechanical fasteners (48) arranged on the backing layer (30) and integral with the backing layer (30), wherein each of the mechanical fasteners (48) of that plurality has (i) head portion (42) comprising the distal end (44) of the fastener (48) and (ii) a stem portion linking the head portion (42) of the fastener (48) with the backing layer (30) and comprising the proximal end (50) by which the fastener (48) is linked with the backing layer (30), wherein the stem portion is tapered and the width (52) of the head portion (42) is greater than the width (58) of the stem immediately underneath the head portion (42) such that the head portion (42) forms an overhang and wherein the width (52) of the head portion (42) is equal or less than the base width (54) of the fastener (48) at the proximal end (50) and wherein the base width (54) is greater than their height (26) of the fastener (48), and wherein the thickness (32) of the backing layer (30) is from about 10 μm up to about 75 μm.
In a twelfth embodiment, the present disclosure provides a web (40) according to the eleventh embodiment, wherein the head portion (42) forms an overhang on each side of the stem.
In a thirteenth embodiment, the present disclosure provides a web (40) according to the eleventh or twelfth embodiment, wherein the backing layer (30) has a thickness of from about 10 μm up to about 50 μm.
In a fourteenth embodiment, the present disclosure provides a web (40) according to any one of the eleventh to the thirteenth embodiment, wherein the backing layer (30) and the fasteners (48) comprise the same thermoplastic material.
In a fifteenth embodiment, the present disclosure provides a web (40) according to any one of the eleventh to the fourteenth embodiment, wherein the fasteners (48) have a height (26) of from about 90 up to about 900 μm.
In a sixteenth embodiment, the present disclosure provides a web (40) according to any one of the eleventh to the fifteenth embodiments, wherein the fasteners (48) have a base width (54) from about 105 μm to about 1010 μm.
In a seventeenth embodiment, the present disclosure provides a web (40) according to any one of the eleventh to the sixteenth embodiment, wherein the fasteners (48) have a ratio of width (52) of head portion to base width (54) is from about 1.0:1.1 to about 1 to 5.
In an eighteenth embodiment, the present disclosure provides a web (40) according to any one of the eleventh to the seventeenth embodiment, wherein the fasteners (48) have a ratio of base width (54) to height (26) of from about 1.2:1.0 to about 10.5:1.0.
In a nineteenth embodiment, the present disclosure provides a web (40) according to any one of the eleventh to the eighteenth embodiment wound up into a roll.
In a twentieth embodiment the present disclosure provides a method of making a web (40) according to any one of the eleventh to the nineteenth embodiment, comprising
In a twenty-first embodiment, the present disclosure provides an absorbent article (100) comprising the web (40) of fasteners according to any one of the eleventh to the eighteenth embodiment.
In a twenty-second embodiment, the present disclosure provides a method of making an absorbent article (100) according to the twenty-first embodiment comprising (i) providing an absorbent article, (ii) connecting the web (40) of fasteners according to any one the eleventh to the eighteenth embodiments to the absorbent article (100).
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2018/058305 | 10/24/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62577907 | Oct 2017 | US |
