MXPA99011453A - Method and apparatus for forming headed stem mechanical fastener structures - Google Patents

Abstract

There is provided a method of deforming the hook head portions (23) of hook elements (25) on a web backing (30). The hook elements on the web backing are fed into a nip (64) formed between a support surface (68) and an upper heated surface (66) having a durameter hardness of less than 90 Shore A. This upper heated surface compressively engages the hook head (25) causing it to turn down and permanently deform. This increases the uniformity of the hook head elements forming a fiber engaging crook region.

Description

METHOD AND APPARATUS FOR FORMING MECHANICAL FIXED HEADSET HOLDER STRUCTURES FIELD AND BACKGROUND OF THE INVENTION The present invention relates to a method and an apparatus for finishing vertical filaments to form hooks of mechanical fasteners. More particularly, the invention relates to a method for forming topped hook configurations with greater uniformity and ease of hooking to the fiber. Hook and eyelet mechanical fasteners are widely used for a wide range of products and applications. There are a variety of methods for forming hook materials for use in these mechanical fasteners of the eyelet and hook closure type. During these years it has been found that the hooks have different hooking mechanisms and characteristics according to the materials of the eyelet, depending on the hooks and / or the material of the buttonhole. This limits the practical applicability of any particular hook forming technique to produce hooks that can be applied to only certain types of uses or for use with only certain types of corresponding eyelet materials. Some of the first hook materials are REF .: 32210 formed using the procedures described in U.S. Patent Nos. 2,717, 437 and 3,009,235 wherein special warps of vertical nylon yarn are cut so as to form nylon hook material with the open end and non-functional vertical filaments. The hooks formed by these types of methods are large (e.g., approximately 2 mm) requiring the use of open hair eyelet materials and have a rather low number of hooks per unit area. These hooks are also quite abrasive and therefore are not very suitable for uses in which the hooks could be in contact with sensitive skin. Hooks of this type are still used today due to durability in prolonged use. Similar types of hook structures are formed in accordance with the method of U.S. Patent No. 3,594,865 wherein a thermoplastic material is formed directly on a J-shaped "wire" hook using shallow J-shaped matrices. These "wire matrices" are formed in a continuous loop of mold material, which is passed through an extruder. The extruder pushes the molten plastic, such as nylon, into the wire dies while also impregnating a fabric coil immediately below the mold material of the wire matrix. Exiting the extruder, the resin Excessive thermoplastic is separated from the surface of the wire matrix molds. The flexible hooks remain in the backrest when the matrix is removed essentially by pulling the now solidified hooks and the backing away from the mold material of the wire matrix. U.S. Patent No. 3,594,863 relates to a similar apparatus for producing a web having filaments. The two patents indicate that the described methods can produce a wide variety of forms. U.S. Patent No. 3,594,865 states that the traditional method for directly injection molding a hook is limited to shapes that have to be tapered from the base to the tip. However, the hook shapes formed by these patents are relatively large and the hooks have to taper from the outer face to the opposite side along the length of the hook. The types of traditional molded hook shapes indicated in U.S. Patent No. 3,594,865 are like those described in U.S. Patent Nos. 4,984,339 and 5,315,740. These patents disclose shaped J-shaped hooks having a profile defined by a generally concave face, with smooth inner contour and an outer face of generally convex shape. The hook tapers continuously and smooth from the base of the hook towards the Free end of the hook. The hook is designed in such a way that it will not deform to release a buttonhole engaged in the hook in cutting mode or with a desired applied force. The above-mentioned patent discloses a similar hook having a low displacement volume for the area defining the tip of the hook. This is described as being convenient for use in applications such as disposable diapers and the like. Although these J-shaped hooks are generally adequate performance materials, they are very difficult to manufacture, particularly when making very small hooks such as those described in Patent No. 5,315,740. The small, complex shaped mold cavities are very difficult to manufacture and when they form extremely small hooks a proportionally larger number of mold cavities of J-shaped hooks have to be formed. The mold cavities of small complex shape are also much more susceptible to clogging and loss of definition of the molding cavity due to wear. Extremely flexible and inexpensive methods for forming hooks of a wide variety of sizes and shapes are described in PCT applications Nos. WO 94/23610 and 92/04839, as well as in the U.S. series No. 08 / 723,632. Using the methods described in these patents and the patent applications, a backing having a large number of vertical thermoplastic filaments is fed through a gap between a contact line formed, for example, by two calendering cylinders. The upper contact line is smooth and heated so that the distal ends or tips of the filaments ~ deform under heat and mechanical pressure, forming several types of finishing structures depending on the conditions of the selected contact line, the relative speed of the filaments in the line of contact, and the size and shape of the filaments. The non-deformed filament portion and the generated cap together form a hook structure. The precursor material, a backing having vertical undistorted thermoplastic filaments, can be formed by molding techniques. However, the formation and use of mold cavities in the form of vertical filaments are much simpler and less problematic than the formation of J-shaped hook molds. For example, these simple mold cavity shapes have much less possibility of clogging or wearing out adversely, depending on the selection of mold materials. In addition, it has been found that using this method it is relatively easy to form large numbers of hooks separated very closely by unit area, which is Particularly suitable for coupling with materials of non-woven eyelets or relatively soft fabrics. These slightly fluffy eyelet materials are generally also inexpensive, which makes this hook structure extremely convenient for low cost limited use applications such as disposable garments. The feel of these hook materials is also advantageous. Due to the high density of hooks and / or because the hooks have a flat or relatively flat top surface, the hooks are extremely pleasant to the skin, non-abrasive and have a film-like texture. Preferred hook materials are those which are essentially difficult to perceive as such at casual contact of the skin. This makes the hooks useful for disposable garments worn close to the skin (eg, diapers or surgical gowns). The present invention relates to a method for improving the aforementioned method of forming hooks and hooks formed by it.

DESCRIPTION OF THE INVENTION In the method for forming filament head mechanical fasteners of the present invention, a precursor web material having a set of vertical thermoplastic filament bases and hook heads projecting distally from at least one surface of the fabric backing. The vertical filament bases may have any shape but preferably have a substantially constant width along the length of the filament or may taper inwardly from the backing of the fabric. In the upper portion of the base of the filament is the hook head having a portion projecting outwardly from the base of the filament. This portion of the hook head projecting outward forms a portion that engages fibers. The hook head can be formed generally by deforming a portion of the filament tip in a finishing process or in a molding process. A hook head formed by capped or similar procedures will typically have a fiber engaging portion that extends outwardly from the base of the filament in any of a variety of angles depending on the process conditions, e.g. , of the finishing procedure. In the method of the invention, the precursor fabric material having vertical filament base portions and hook heads, with fiber-engaging portions projecting outward, is fed into a nip that forms a separation. The separation can have a constant width or can be tapered. The tapering of the separation is performed along its length preferably from an initial width given to a narrower end width, however, the spacing could taper in some cases slightly wider in at least a portion of the length of separation. The contact line forms a compression zone with a heated upper surface having an effective durometer hardness of less than 90 Shore A. The heated upper surface engages by compression to the hook heads causing the portions that hook fibers to be projecting from the hook head bend downward and deform permanently. The fiber-engaging portions, bent downward, permanently deformed, have an outward tip that is below a plane formed by the upper end portions of the hook heads. The portions hooking hook head fibers preferably form a downward angle from the upper portion of the hook head towards the base fabric. In addition, preferably both the upper surface and the bottom surface of the fiber engaging portion form an angle towards down. This downward angle on the bottom surface forms a portion or Curved region included.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic illustration of a method for forming a web of material having vertical filaments to manufacture the finned filament fasteners.

Figure 2 is a schematic illustration of a method for finishing or deforming hook heads using a calendering system.

Figure 3 is a schematic illustration of an alternative apparatus for forming headed filament fasteners such as those used in the method of the invention.

Figure 4 is a side view of a headed filament fastener as used in the method of the invention.

Figure 5 is a perspective view of a headed filament fastener produced by the method of the invention.

Figures 6A and 6B are before and after photographs of a headed filament fastener produced by the method of the invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The precursor fabric material used in the method of the invention is a cloth backing with a given width dimension and an indeterminate length dimension. The backrest has numerous vertical hook elements having filament bases projecting from at least one surface. At the distal end of the filament bases there are portions of head with upper portions and portions that hook fibers, which project outwards. The hook elements can be distributed throughout the backrest or only on a portion of the backrest. The hook heads or the bases of the filaments can have various shapes, however, the upper portion of the hook head portion on the filament base is generally in substantially the same plane as the portions that hook fibers of the portion. of hook head. However, portions that hook hook-head fibers can project upward from the top of the head of the head. hook or slightly down from the top of the hook head. The hook head portions of the mechanical fasteners are preferably provided by means of a finishing method. In the preferred finishing process, a heated surface element is positioned opposite to a supporting surface element to form a contact line preferably extending across the width of the backing fabric or surface or at least through a substantial portion of the fabric having vertical filaments. The contact line also it extends along the length of the fabric at a given distance forming a compression zone. The precursor fabric is fed into the contact line that forms a separation. The separation tapers from a given initial width in the compression zone. The tips of the filaments are initially engaged in a width of the given inlet spacing and are compressed in the contact line to a width of the given final spacing. In this compression zone the contact line progressively engages and compresses the polymer filaments between the surface element of the heated contact line and the support surface element. Although this compression is preferably continuous, it can be intermittent and / or different compression values in the compression zone as determined by the width of the gap and the change in the width of the gap along the length of the contact line. This heat and this compression cause the distal ends of the vertical thermoplastic filaments to be deformed into finished or hooked head structures which can engage a fibrous eyelet material. In a preferred embodiment, at least in a portion of the compression zone the surface of the heated contact line element is provided with at least one series or set of structures of peaks and valleys (grooves), wherein the average depth between the peak and the valley is generally ba bOO microns. The average spacing of the adjacent peak structures is less than the average width of the filament base immediately adjacent to the end portions of the filament before being deformed by the heated surface element of the contact line. Preferably, the peak structures are spaced apart so that each end portion of the filament is brought into contact with two to twenty, preferably four to ten, peak structures while being deformed. A given set of peak and valley structures preferably extends in shape longitudinally at a distance at least equal to the average distance between adjacent vertical filament elements (closest neighbor distance averaging in at least two directions) and preferably continuously along the length of the separation element heated in the area Of compression. Similarly, sufficient peak and valley structures are provided in a given set so that the adjacent peak and valley structures of the set extend laterally at least a distance equal to the average distance between the adjacent vertical filament elements. (closest average neighbor distance in at least two directions). The peak and valley structures in the heated contact line element provide topped filament hooks having a substantially increased directionality and, depending on the structure, more uniformity of the shape of the hook head across the length and width of the cloth. The method and apparatus of the invention relate to the deformation of pre-formed hook heads of hook elements in a precursor fabric. The precursor fabric is provided with a vertical assembly of hook elements having base portions of thermoplastic filaments and portions thereof. of hook heads with portions that hook fibers that project outward, which project away from a cloth backing. The apparatus includes an elastically deformable heated deformation surface element having an effective durometer hardness at the use temperature of less than about 90 Shore A, preferably less than 80 Shore A, as opposed to a supporting surface element which forms a line of contact, which can be tapered from an entry gap width to a final gap width defining a compression zone. The effective durometer hardness of the deformation surface is generally greater than 30 Shore A and preferably greater than 50 Shore A. A feeding element is provided for feeding the precursor fabric into and through the compression zone of the nip. In the method of the invention, the width of the contact line spacing may decrease in the compression zone, but the contact line may also have a generally constant spacing along at least a portion of its length. length in the compression zone or the width of separation may decrease and increase intermittently or decrease in different proportions, or combinations of previous Usually, the length of the compression zone of the contact line is defined by a first inlet separation width and a second separation, which is generally equal to or less than the first separation width, which defines a final contact line separation . The width of the entry spacing of the given contact line is defined by the thickness of the backing substrate web and the average height of the vertical hook elements at the point at which the hook elements of the precursor web material engage. first by compression the heated upper surface that defines the contact line. The width of the final spacing is the narrowest spacing on the contact line after which the fabric and deformed hook heads are substantially released by compression with the surface element of the heated nip. The narrower spacing or linear pressure is generally set to selectively deform the hook-engaging portion of the hook head, which depends on the hardness of the material forming the hook element, the shape and spacing of the hooks. hook elements, the hardness of the deformation surface and the temperature of the deformation surface. This selective deformation results in the deformation of the portions that hook fibers projecting outwardly from the hook heads fiber engaging portions projecting outward from the hook heads so that they generally project at an angle downwardly from the upper portions of the hooks. hook head towards the base fabric. This downward angle (measured from a reference line taken from the top of the hook head and parallel to the backrest) is generally from 0 to 70 degrees, preferably from 5 to 60 degrees, more preferably from 5 to 35 degrees (defined by a linear extension running from a central region of the portion of the upper part of the hook head to one end of the fiber hook portion of the hook head). The filament hook fasteners with head of the invention can be formed using a backing material having a set of thermoplastic, plastically deformable, vertical filaments. These vertical hook elements are preferably formed in an integral backrest of the same thermoplastic material. Suitable thermoplastic materials include polyolefins such as polypropylenes or polyethylenes, polyamides such as nylon, polyesters such as poly (ethylene terephthalate), plasticized polyvinyl, copolymers and mixtures thereof, optionally, with other polymers or plasticizers, or the like. A suitable method for forming the fabric used to form this precursor fabric material for a fined filament type of a headed filament hook fastener is shown in Fig. 1. A pre-selected thermoplasic resin feed stream 4 is fed by conventional means in an extruder 6 that melts the resin and moves the heated resin to a matrix 8. The matrix 8 extrudes the resin as a broad ribbon of material on the mold surface 10, e.g. , a cylinder, having a set of mold cavities 12 in the form of elongated holes, which are preferably tapered to facilitate the removal of the solidified resin from the mold cavities. These mold holes or cavities are preferably in the form of straight cavities (ie, only one axis in the longitudinal direction). The mold cavities can be connected to a vacuum system (not shown) to facilitate the flow of the resin into the mold cavities. This could require a blade or doctor blade to remove excess extruded material on the inside face of the mold cylinder. The mold cavities 12 preferably end in the mold surface having a open end for the entrance of the liquid resin and a closed end. In this case, a vacuum 14 could be used to evacuate at least partially the mold cavities 12 before entering the matrix 8. The mold surface 10 preferably matches that of the matrix 8 where they are in contact to avoid that the excess resin is extruded, eg. , the lateral edges of the matrix. The mold surface and the cavities can be cooled by air or water, or the like, before releasing the backing and the vertical filaments formed integrally from the mold surface such as by a release cylinder 18. This provides a cloth 20 of a back 30 having vertical filaments 28 formed integrally of thermoplastic material. Alternatively, the vertical filaments could be formed in a preformed backing or the like by extrusion molding or other known techniques. The filaments formed by the method of Fig. 1, or similar methods, can be topped to form a hook element of precursor fabric material by the use of a heated nip that can be formed by two calendering cylinders, 22 and 24, as shown in Fig. 2. The heated calendering cylinder 22 is brought into contact with a predetermined portion of a distal end 26 of the filaments 28 projecting upwards from the backrest 30. The temperature of the cylinder will be that which easily deforms the distal ends 26 under pressure created by the contact lines in the compression zone 35 without causing the resin to stick to the surface of the cylinder. 22. The surface of the cylinder 22 can be treated with release coatings resistant to high temperatures to allow higher temperatures and / or longer contact times between the tips of the filaments or distal ends 26 and the heated cylinder 22. In the method of the invention a contact line is used, as shown in Fig. 2, to further deform a mechanical filament fastener element with head, as shown in Fig. 4. The surface, e.g. , the heated deformation cylinder 22 is provided with a material having a durometer hardness which will allow the hook head fiber engaging portion 23 to be deformed by compression to the hook head top portion 25 by means of the heated deformation cylinder material without substantially deforming the filament base portion 27 and / or the upper portion of the hook head 25. As such with relative rigidity or higher modulus material forming the base portion of filament, base portions of filaments with larger average diameter, higher density of hook elements or a deformation cylinder of higher temperature, the material of the cylinder may have a higher relative hardness of durometer hardness. The material forming the outer surface of the heated deformation cylinder can be any relatively thermally stable elastically deformable material such as silicone rubber. The outer surface of the heated deformation cylinder 22 can be treated with release materials as above. The contact time between the hook head 25 and the heated deformation surface element should be relatively short such that the heated deformation surface element deforms the projecting fiber hook portion 23 of the hook head 25. without substantial deformation of the filament base portion 27. The heated deformation element is then elastically recovered to be available for deformation of subsequent fiber engaging portions. As shown in the Fígs. 6A and 6B, for example, the method of the invention improves the uniformity of a hook head shape by deforming the fiber engaging portions 23 of the hook heads 25 to the same relative downward slope, assuming that the height of the original hook element of the precursor fabric and the thickness of the backing are relatively uniform. Such uniformity of the hook elements of the precursor fabric and the thickness of the backing are obtained by means of the preferred finishing method, as described with respect to Fig. 2 to originally form the hook elements. Although the thickness of the precursor fabric (e.g., the total height of the hook element and the thickness of the fabric backing) will be substantially uniform with this method of forming the hook elements, the fiber engaging portions that are Outwardly projecting 23 may vary significantly with respect to their orientation relative to backup, particularly from batch to batch. This variability is substantially reduced by the method of the invention while also providing a fiber engaging portion 23 of the downwardly projecting hook having an increased ability to grip individual fibers of a corresponding fibrous eyelet material. Alternative methods and apparatuses (e.g., Fig. 3) for producing the filament fasteners with head of the invention could be similar to those disclosed. in the pending US application, series No. 08 / 781,783, except modified to provide a heated cylinder of adequate hardness. In the method and apparatus of Fig. 3, a finishing apparatus 50 is used to form a filament fastener element with head 52 having numerous generally uniform heads 32 or to further deform the portion that engages fibers of a filament element. Filament fastener with head according to the apparatus and method of the invention as described above. A precursor fabric 20 having a backing 30 with a back surface 58 and a multiplicity of polymer filaments 28 or filament fastener elements formed projecting distally from a front surface b3 is directed to an inlet of a contact line 64. The inlet of the contact line 64 is formed between a heated cylinder 66 and a curved support structure 68. The curved support structure 68 preferably has a shape that generally corresponds to that of the heated cylinder 66 at a slightly larger radius of curvature . The piston 80 provides a compressive force between the curved support structure 68 and the heated cylinder 66. The contact line 64 defines a first input separation width at an input of the contact 72 and a second final separation width at an outlet of the contact line 76 defining a compression zone 75. The second final separation width is preferably smaller than the first separation width. In the preferred embodiment, the separation width of the contact line 64 decreases continuously in a substantially linear proportion at least in some region. Preferably, this substantially linear change in the width of the gap occurs at least in a region immediately adjacent to the input gap width of the contact line between the entry of the contact line 72 and the line output. 76. In an alternative embodiment (not shown), the contact line 64 may decrease to a minimum value at an intermediate location between the input 72 and the outlet 76 of the contact line or decrease then increase and then decrease again, etc. A fluid, such as air or water, can be introduced through the pipe 78 to the interface between the back surface 58 of the backing 30 and the surface 116 to create a fluid support. The surface 116 may optionally be coated with a low surface energy material such as polytetrafluoroethylene (PTFE) or weight polyethylene. ultra high molecular Without the air support, the back 30 tends to wrinkle when it enters the contact line 64, potentially causing breaks in the backrest 30. A piston 80 is provided to position the curved support structure 68 relative to the heated cylinder 66. Curved support structure 68 can also rotate along a pivot point 82 to further adjust the gap width of the contact line 64 in the compression zone 75. When a filament fastener with head is formed from filaments vertical using the apparatus, eg. , Fig. 3, the relative speed of the heated cylinder 66 and the line speed of the precursor web 20 determine the total shape of the capped heads 32 in the headed filament holder 52. The rotation speed of the heated cylinder 66 it may be greater than, less than or equal to the line speed of the precursor web 20. For some applications, the cylinder 66 may be stationary while the precursor web 20 moves through the contact line. Alternatively, the cylinder 66 can be rotated in a direction opposite to the direction of movement of the precursor fabric 20. Synchronous movement of the heated surface 22 or 66 is preferred to form more heads symmetrical 98 around the filament (ie, generally symmetric with respect to two or more reflection planes). Alternatively, the relative movement of the heated surfaces 22 and 66 may be slightly asynchronous to achieve asymmetric heads 98 around the filament (i.e., with one or fewer reflection planes), such as J-shaped hooks. Also to form a web precursor with topped filament fastener elements the specific shape and orientation of the topped heads of the topped heads 32 can be determined by the relative size, spacing and orientation of the peaks and grooves on the heated surface element (as mentioned above), the relative speeds of the fabric 20 and the heated surface element, as well as the temperature and shape of the heated surface element and the formed spacing and the length of the compression zone. If grooves are provided in the heated surface element, they are preferably continuous and uniform across the heated surface element. The grooves can be oriented in the machine direction or oriented in the direction of movement of the fabric through the contact line in the compression zone. This results in a filament head which is longer in the direction of the machine or the movement of the fabric than in the transverse direction. It is also possible that the orientation of the grooves forms an angle in a heated surface element, with respect to the direction of the machine or the direction of movement of the fabric. Where the peaks and grooves form an angle with respect to the direction of the machine, the resulting topped heads may be provided with elongated shafts at angles with respect to the longitudinal direction of the fabric. However, when the peaks and grooves form an angle with respect to the machine direction, the relative speeds of the fabric and the heated surface element should substantially coincide to prevent the peaks from scraping or removing the filaments. The angle of the sets of peaks and grooves with respect to the machine direction can range from greater than zero to 180 degrees. In general, the filament head fastener elements of precursor fabric used in the method of the invention, regardless of how they are formed, are in the form of base portions of substantially vertical filaments at an angle of approximately 90 degrees to the substrate of the filament. backrest, however, this angle can range between 80 and 100 degrees, preferably between 85 and 95 degrees. The hook head portion is formed in a distal end portion 26 of the filament portion. The hook heads can be elongated in one or more directions by forming the portions that hook fibers. These fiber-engaging portions extend outwardly from the filament portion at any angle so that they can project upwards away from the backing of the film, parallel to the backing of the film, or even downward with respect to the backing of the film. . The preferred hook head portions are generally flat or flat top surfaces as formed by a top-off method. These hook heads are suitable for hooking products of relatively open woven and non-woven eyelets as used in disposable or limited use garments. A flat upper or flat upper hook head surface is also smooth to the touch and is not abrasive unlike molded hooks which generally have a distinct apex (eg, in the inclinations of the hooks away from a peak in minus two directions). Vertex hook fasteners are less pleasing to the skin, making them less suitable for use in relation to sensitive skin (eg, in a baby diaper).

For use in diapers and similar garments, the topped filament hooks are preferably of uniform height, preferably approximately 0.10 to 1.3 mm in height and more preferably approximately 0.2 to 0.5 mm in height. Particularly in the preferred precursor-finished filament hook elements, the deformed hooks have a density in the backrest preferably of 60 to 1600 hooks per square centimeter and more preferably of about 100 to 700 hooks per square centimeter. The base portions of the filaments have a diameter adjacent to the head portions of the deformed hooks preferably of 0.07 to 0.7 mm, and more preferably of about 0.1 to 0.3 mm. The deformed hook heads project radially beyond the base portions of the filaments on at least one side preferably, on average, about 0.01 to 0.3 mm, and more preferably, on average, about 0.02 to 0.25 mm and have thicknesses average between its outer and inner surfaces (i.e., measured in a direction parallel to the axis of the filaments) preferably from about 0.01 to 0.3 mm and more preferably from about 0.02 to 0.1 mm. The hook head portions have a ratio between average diameter (ie, measured radially of the axis of the heads and the filaments) and thickness of the average head preferably from 1.5: 1 to 12: 1, and more preferably from 2.5: 1 to 6: 1. For good flexibility and strength, the backing of the headed filament fastener is preferably a film of 0.02 to 0.5 mm thick, and more preferably 0.06 to 0.3 mm thick, especially when the fastener is made of polypropylene or a copolymer of propylene and ethylene. For some uses, a stiffer backing could be used, or the backing can be coated with a layer of pressure-sensitive adhesive on its surface opposite the surface with the hooked filament hooks through which the backing could adhere to a substrate. . For most uses of the eyelets and hooks, the deformed hook elements should be distributed substantially uniformly over the entire surface area of the fabric backing, generally • in a square, stepped or hexagonal configuration. The method of the invention produces vertical thermoplastic hook projections as shown in Fig. 5 and Figs. 6B with a substantially undistorted filament base portion 27 and a hook head portion 25 'having a deformed fiber engaging portion 23'. The deformed fiber engaging portion 23 ' It projects down. Preferably, the lower surface of the fiber engaging portion also projects downwardly forming a curve 26 'between the lower face of the fiber engaging portion 23' and the filament base portion 27. The degree of deformation of the filament engagement portion 23 'depends on the relative hardness of the heated cylinder 22; the shape, thickness and material forming the fiber engaging portion 23; the pressure of the contact line; and the nature of the filament portion 27. The filament fasteners with head of the invention can be produced in long, wide fabrics, which can be rolled up as rolls for convenient storage and shipping. The material of the filament fastener with head in such rolls may have a layer of pressure-sensitive adhesive on the surface of the backing opposite to that of the deformed hook elements, adhesive that can be adhered in a detachable manner to the heads of the deformed hook elements in underlying wraps of the filament holder with head in the roll. These rolls do not require a release liner to protect the layer of pressure sensitive adhesive in the roll. The limited area of the heads to which the pressure-sensitive adhesive on the roll adheres maintains the material of the filament fastener with head in a stable roll form until it is ready for use, and then allows the material of the fastener to be easily unwound from the roll. Pieces of the desired lengths of the headed filament fasteners can be cut from the roll of fastener material and can be secured in adhesive or otherwise to articles such as a fin of a garment to allow the fin to be secured in a manner that can be detached. The deformed headed filament fasteners of the invention can be used particularly in a fastening flap or they can be attached in another manner to a disposable or limited use garment such as a hospital diaper or gown. Filament holders with deformed heads can also be used as auto-coupling fasteners.

TEST METHODS All tests were performed at constant temperature and humidity in a room conditioned at 23 ° C and 50% relative humidity.

Release test at 135 degrees The 135-degree peel test was used to measure the amount of force required to detach a sample of mechanical filament fastener material with a head from a eyelet fastener material sample. A 2-inch piece was placed. x 5 in. (5.08 cm x 12.7 cm) of an eyelet test material on a 2-in. Steel panel. x 5 in. (5.08 x 12.7 cm) using a double-coated adhesive tape. The eyelet material was placed on the panel with the transverse direction of the eyelet material parallel to the longitudinal dimension of the panel. A 1 inch band was cut. x 5 in. (2.54 cm x 12.7 cm) of the mechanical fastener to be tested and a 1"mark was placed. (2.54 cm) from both ends of the mechanical fastener band. The band of hooks was then placed centrally over the buttonhole so that there was a 1"contact area. x 1 in. (2.54 cm x 2.54 cm) between the band and the eyelet material and the guide edge of the band was along the length of the panel. The band and laminate of buttonhole material were rolled manually, once in each direction, using a 4.5 pound (1000 grams) cylinder at a speed of approximately 12 puig. (30.5 cm) per minute. Paper was used between the non-hooked regions of the band and the eyelet material to ensure a maximum hook-up of 1 in. (2.54 cm). Holding the guide edge of the band, the laminate was lightly cut manually about 1/8 inch (0.32 cm), engaging the hook elements of the band in the eyelets. The sample was then placed in a release template at 135 degrees. The template was placed in the lower jaw of an Instron ™ Model 1122 tensile tester. Without previously detaching the sample, the guide edge was placed in the upper jaw with the 1"mark. on the lower edge of the jaw. At a head speed of 12 in. (30.5 cm) per minute a graphic recorder set at a paper speed of 20 in. Was used. (50.8 cm) per minute to record the detachment that was maintained at 135 degrees. An average of the four highest peaks in grams was recorded. The force required to separate the band from the mechanical fastener from the eyelet material was reported in grams / 2.54 cm in width. The reported values are an average of at least five tests.

Debris test at 135 degrees The test of detachment by twisting to 135 degrees was performed in a manner similar to the 135 degree peel test except that the preparation of the sample was different. After the mechanical fastener band was placed on top of the buttonhole material on the panel, a 9 lb. (4 kg) weight was placed on top of the laminate. Then the weight was twisted about 0.5 in. (1.3 cm) in one direction, then 0.5 in. (1.3 cm) in the opposite direction. This was done twice during a total of four twists. The twist detachment test was then performed as described above for the 135 degree peel test.

Fast adhesion This test method was used to determine the force required to disengage a mechanical fastening system of eyelets and hooks after applying a minimum force to engage the material of the mechanical fastener and eyelet material. A 2-inch piece was placed. x 5 in. (5.08 cm x 12.7 cm) of an eyelet test material on a 2-in. Steel panel. x 5 in. (5.08 x 12.7 cm) using a double-coated adhesive tape. The eyelet material was placed on the panel with the transverse direction of the eyelet material parallel to the longitudinal dimension of the panel. A template was then placed 90 degree detachment in the lower jaws of an Instron ™ constant value elongation tensile tester. The buttonhole on the panel was then inserted into the 90 degree peel template. One piece of 1 in. X 1 in. (2.54 cm x 2.54 cm) of mechanical fastener material to a 250 g weight test apparatus using a double coated adhesive tape. The test apparatus was then inserted into the upper jaw of the tensile tester and without applying any pressure was placed on top of the eyelet material. With the speed of the test apparatus set at 12 in. (30.5 cm) per minute a graphic recorder set at a paper speed of 5 in. Was used. (12.2 cm) per minute to record the force required to disengage the fastener material from the eyelet material. The peak value was read from the register and the force was recorded in grams / 2.54 cm in width. The reported values are an average of at least two tests.

Examples Examples 1-4 A precursor fabric material was prepared that had a set of vertical thermoplastic filaments similar to that described for Example of PCT Application No. WO 94/23610. The density of the filaments was 2500 filaments / inch2 (386 filaments / cm2). The filament height was 18 mils (0.46 mm) and the width or diameter of the filaments was 7.9 mils (0.20 mm). The thickness of the fabric backing was. of 4.5 mils. { 127 microns). The precursor fabric was prepared from an ethylene-propylene impact copolymer resin such as those obtainable from Union Carbide as # SRD7-587 and # SRD7-560. The precursor fabric was fed through a contact line formed by two calendering cylinders. The surface of the upper cylinder, which was put in contact with the distal ends or ends of the filaments had a model of structures of peaks and valleys (grooves). The furrows were approximately 0.98 mil (0.025 mm) deep and were separated by 2 mils (0.050 mm). The grooves were oriented in the transverse direction. The temperature of the upper cylinder was set at 290 ° F (143 ° C), and the temperature of the lower cylinder, which was brought into contact with the cloth backing, was set at 60 ° F (16 ° C). The separation of the contact line was 8 mils (0.20 mm) and the precursor fabric was fed through the contact line once. The pressure of The piston that held the calendering cylinders together was enough to compress the fusion zone. The speed of the line was 10.7 meters / minute. The resulting capped filament hooks were elongated in the machine direction. The diameter of the topped in the direction of the machine was 12 mils (0.30 mm) while the diameter of the topped in the transverse direction was 8 mils (0.20 mm). The height of the topped filaments was 13.5 mils (0.34 mm). This elongated topped filament hook fastener was used as a precursor fabric that was fed into a rubber nip. The top cylinder was composed of a 6 in. (15.2 cm) diameter cylinder that was approximately 0.25 in. (0.63 cm) of silicone rubber coated on its outer surface. The durometer of the rubber coating was approximately 58 Shore A. The top cylinder was heated with an electric heating element to a surface temperature of approximately 300 ° F (139 ° C). The support cylinder was approximately 10 in. (25.4 cm) in diameter and had a silicone rubber coating of approximately 0.25 inches (0.63 cm). The durometer of the rubber coating was approximately 70 Shore A. The support cylinder was cooled with mains water. The hook fastener Elongated capped filaments were fed into the heated rubber contact line at a line speed of 55 feet / minute (17 meters / minute) with a contact line pressure of approximately 22 pli. The filament hook fastener with the resulting head was tested for fast adhesion, 135 deg. Detachment and 13b deg. This fastener with hooked filament hooks that was used as a precursor fabric was also tested as a control. The detachment tests were performed in such a way that the detached front part was perpendicular to the elongated axis of the finishes. The eyelet material used for the test was a nonwoven eyelet material similar to that used as the eyelet fastening surface in the Huggies ™ Supreme ™ infant diapers. The results are given in Table I together with the resulting dimensions of the hook head. Using the same contact line pressure and cylinder temperatures, samples of the precursor fabric of elongated capped filament hook fasteners were fed into the heated rubber nip at line speeds of 75 p / min (23 meters / minute), 100 feet / minute (30 meters / minute) and 125 feet / minute (38 meters / minute). The hook fasteners of resulting filaments with heads were also tested. The results of the test and the dimensions of the hook head are given in Table 1.

Table I Example 6 A precursor fabric having rounded, round ("golf tee" shaped) filament fasteners was prepared in a manner similar to that described for the Example of PCT Application No. WO 94/23610. The precursor fabric was prepared from a resin of ethylene-propylene impact copolymer such as those obtainable from Union Carbide as # SRD7-587 and # SRD7-560. The density of the filaments was 1600 filaments / inch2 (247 filaments / cm2). The height of the filaments was 12.5 mils (0.31 mm) and the width or diameter of the finishes was 12 mils (0.30 mm) and the diameter of the filaments was tapered from the base (0.30 mm) just below the top (0.20 mm). The thickness of the finish was 0.03 mm. The thickness of the cloth backing was 5 mils (127 microns). Samples of the round capped filament fastener were fed into a heated contact line as described in Examples 1-4. The pressure of the contact line was 34 pli, the speed of the line was 50 feet / minutes (15 meters / minute) and the temperature of the upper cylinder coated with rubber was 275 ° F (135 ° C). This resulted in a slight bending of the hook head to substantially flatten the fiber hook portion of the hook head.

Example 7 The same precursor fabric used in Example 6 was fed into a heated nip in a manner similar to that described for Example 6 except that the upper rubber cylinder was heated to 280 ° F (137 ° C). This resulted in greater bending of the fiber engaging portion compared to Example 6 to give a mushroom-shaped hook head.

Example 8 The same precursor fabric used in Example 6 was fed into a heated nip in a manner similar to that described for Example 6 except that the upper rubber cylinder was heated to 304 ° F (151 ° C). This treatment resulted in a mushroom-shaped hook head that completely curved until the fiber engaging portion touched the filament.

It is noted that in relation to this date the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property

Claims (15)

1. A method for forming a mechanical filament fastener with head having a backing cloth and a set of vertical hook elements with vertical filament base portions and hook heads with downwardly projecting fiber engaging portions characterized in that it comprises : a) providing a fabric, having a cloth backing, with a set of projections of substantially vertical thermoplastic hook elements each formed at least in part by a substantially vertical filament base portion and a hook head portion that has a fiber engaging portion extending outwardly from the base portion of the filament, the fabric having a first average thickness; b) providing a contact line having at least a first heated deformation surface element and at least one second opposing surface element defining a separation having a zone of compression defined by a first width of inlet spacing and a second end spacing, wherein the first spacing width is substantially equal to or less than the first average thickness of the fabric; moving the fabric along a cloth path in, and through, the compression zone such that at least a portion of the set of fiber engaging portions of substantially vertical hook elements is preferably deformed downwardly by elastic deformation of the heated surface deformation element.

2. The method according to claim 1, characterized in that the heated surface deformation element has an effective durometer hardness less than 90 Shore A.

3. The method according to claim 1, characterized in that the heated surface element has a Shore A hardness from 30 to 90.

4. The method according to claim 1, characterized in that the first speed is substantially equal to the second speed.

5. The method according to claim 4, characterized in that the first speed is substantially different from the second speed.

6. The method according to claim 1, characterized in that the compression zone has two or more heated surface elements.

7. The method according to claim 1, characterized in that the vertical hook projections are formed by a polyolefin.

8. The method according to claim 1, characterized in that the first and second surface elements forming the contact line are formed by two calendering cylinders.

9. The method according to claim 1, characterized in that the width of Separation decreases between the first inlet separation width and the second final separation width.

10. The method according to claim 1, characterized in that the heated surface deformation element has an effective durometer hardness from 50 to 80 Shore A.

11. The method according to claim 1, characterized in that the heated surface deformation element has an outer surface formed by silicone rubber.

12. The method according to claim 1, characterized in that the fiber engaging portion of the non-deformed hook heads projects upwards from the top of the hook head.

13. The method according to claim 1, characterized in that the fiber engaging portion of the deformed hook heads projects at an angle from 0 to 70 degrees down from the top of the hook head towards the cloth backing.

14. The method according to claim 1, characterized in that the fiber engaging portion of the deformed hook heads projects at an angle from 5 to 60 degrees down from the top of the hook heads towards the cloth backing.

15. A mechanical filament fastener with head characterized in that it has a backing cloth and a set of vertical hook elements with vertical filament base portions and hook heads with downwardly projecting fiber engagement portions, said mechanical filament fastener with head is obtained by the method of any of claims 1 to 14.