METHOD AND APPARATUS FOR PRODUCING HOOK FASTENERS
20170265602 · 2017-09-21
Assignee
Inventors
Cpc classification
B29C59/046
PERFORMING OPERATIONS; TRANSPORTING
B29C59/04
PERFORMING OPERATIONS; TRANSPORTING
B29C59/025
PERFORMING OPERATIONS; TRANSPORTING
B29L2031/729
PERFORMING OPERATIONS; TRANSPORTING
Y10T24/2792
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
Abstract
Apparatus and process are described for forming projections on a substrate for use as hook-type fasteners in touch fastening systems, wherein vibration energy may be used to soften a substrate which may be positioned between a mold and a source of vibration. The mold may include a plurality of cavities into which the softened substrate may be forced to form the projections. The substrate may comprise a film, sheet, web, composite, laminate, etc. and be useful as an attachment strip for temporary or permanent fastening. The source of vibration may be an ultrasonic horn. The process to form such projections may be operated in a continuous, semi-continuous or intermittent manner.
Claims
1-41. (canceled)
42. A process for forming projections on a substrate comprising: providing a first device having an outer surface; providing a solid substrate material having a first surface; providing a second device as a source of vibration energy; wherein one or both of the first device and the second device contain a plurality of cavities, the cavities having a shape to produce projections, wherein the projections have a shape of one or more of hooks, curved pins, and angled pins, wherein the angled pins have a rectangular cross section; positioning the substrate material between the first device and the second device; applying power to the second device to locally soften the substrate material such that a portion of the softened substrate material is forced into the cavities to form the projections on a portion of the first surface of the substrate material and a portion of the substrate material serves as a carrier for the projections.
43. The process of claim 42, wherein applying power to the second device comprises applying intermittent power to the second device.
44. The process of claim 42, wherein providing a substrate material comprises providing a film, sheet, web, composite, laminate, foam, fabric, non-woven, fiber-reinforced composite, thermoplastic, and/or thermoset material.
45. The process of claim 42, wherein providing the substrate comprises providing a first layer and a second layer, the first layer having one or more openings which expose a surface of the second layer, and wherein forming the projections comprises forming projections on the surface of the second layer.
46. The process of claim 42, wherein providing the substrate material comprises providing a laminate comprising continuous and/or intermittent layers of different materials.
47. The process of claim 42, further comprising applying vibration energy to aid in removing the projections from the cavities.
48. The process of claim 42, further comprising forming apertures in the substrate.
49. The process of claim 42, further comprising passing a second substrate material between the substrate material and the first device or the second device and exposing the second substrate material to the vibration energy causing the second substrate material to adhere to the substrate material.
50. The process of claim 49, wherein the second substrate material comprises a film, sheet, web, composite, laminate, foam, fabric, non-woven, fiber-reinforced composite, thermoplastic, and/or thermoset material.
51. The process of claim 42, further comprising passing a second material between the substrate material and the first device or second device, wherein the second material comprises paper.
52. The process of claim 42, wherein a cross section of the projections is at least one of rectangular, square, polygonal, and elliptical.
53. The process of claim 42, wherein the cross section of the projections is rectangular.
54. The process of claim 42, wherein at least a portion of the first device and/or the second device includes a wavy surface that forms at least a portion of the substrate into a creped area.
55. The process of claim 42, wherein the first device comprises a first rotating roll.
56. The process of claim 55, wherein the second device comprises a second rotating roll.
57. The process of claim 42, wherein the first device comprises a rotating roll, and the second device comprises a stationary second device.
58. The process of claim 42, wherein the second device is a source of mechanical, electromechanical, or acoustical energy.
59. The process of claim 42, wherein the second device comprises an ultrasonic horn.
60. The process of claim 42, wherein the cavities are arranged to form an intermittent pattern of projections on the substrate.
61. An apparatus for forming projections on a substrate comprising: a first device having an outer surface; a second device as a source of vibration energy to soften the substrate material; wherein one or both of the first device and the second device contain a plurality of cavities, the cavities having a shape to produce projections, wherein the projections have a shape of one or more of hooks, curved pins, and angled pins, wherein the angled pins have a rectangular cross section, wherein the second device is constructed and arranged to locally soften the solid substrate material such that a portion of the softened substrate material is forced into the cavities to form the projections on a portion of a first surface of the substrate material and wherein a portion of the substrate material serves as a carrier for the projections.
62. The apparatus of claim 61, wherein a cross section of the projections is at least one of rectangular, square, polygonal, and elliptical.
63. The apparatus of claim 62, wherein the cross section of the projections is rectangular.
64. The apparatus of claim 61, wherein at least a portion of the first device and/or the second device includes a wavy surface that forms at least a portion of the substrate into a creped area.
65. The apparatus of claim 61, wherein the first device comprises a first rotating roll.
66. The apparatus of claim 65, wherein the second device comprises a second rotating roll.
67. The apparatus of claim 61, wherein the first device comprises a rotating roll, and the second device comprises a stationary second device.
68. The apparatus of claim 61, wherein the second device is a source of mechanical, electromechanical, or acoustical energy.
69. The apparatus of claim 61, wherein the second device comprises an ultrasonic horn.
70. The apparatus of claim 61, wherein the cavities are arranged to form an intermittent pattern of projections on the substrate.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain principles of the invention.
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DETAILED DESCRIPTION
[0045] Molded hook fasteners have generally been molded by, for instance, extruding or injecting a thermoplastic melt on a rotating drum, or mold, the mold comprised of a lamination or stack of metal plates, the plates having recessed or notched edges or otherwise designed to provide a series of cavities along the outer periphery that may be filled by the molten polymer. A strip-like base portion may be simultaneously molded from which projections, or hooks, molded in the cavities, may protrude.
[0046] It has been found that a relatively less complicated and relatively less expensive process may use vibration energy to soften the polymer to manufacture the projections (hooks, mushroom heads, etc.) instead of the extrusion or injection processes. In one exemplary embodiment, as shown in schematic cross-sectional side view in
[0047] During operation, the vibrating source 13 is positioned in close proximity to the outer surface of the rotating molding roll 15 and in contact with the substrate of thermoplastic material 11 being processed. The source of vibration 13 may include, but not be limited to, a vibrating ultrasonic horn, for example. These horns may be made from metals such as aluminum or titanium and are sold in the United States by companies such as Branson Ultrasonics, Dukane or Sonitek, and in Europe by a company such as Mecasonics. The source of vibration 13 may be vibrated in frequencies between about 50 Hz to about 50 kHz, as required. Other sources of vibration energy may be utilized, including but not limited to, a rotating eccentric roller, high pressure sound waves or other mechanical and/or electromechanical or acoustical forms of vibration energy. Such energy may therefore be transferred to a substrate and assist in the formation of the projection herein.
[0048] A portion of the thermoplastic material substrate 11 in contact with the molding roll 15 and vibrating source 13 may be softened by the vibration energy from the source and a desired portion of the thermoplastic material caused to enter into the cavities 17 of the molding roll forming hook-shaped or otherwise shaped elements or projections 19 on the front surface of the film or sheet 21 as the roll turns. This process may be referred to as rotary forming. Reference to a force may be understood as applying a requisite amount of pressure to the thermoplastic material to assist in its entry and fill-out of the cavities 17. The thermoplastic sheet 21 may function as a carrying strip for the hooks 19.
[0049] Thermoplastic materials which may be used to produce the hook fasteners may include, but not be limited to, polyamides, polyolefins such as polypropylene and polyethylene, acrylonitrile-butadiene-styrene (ABS), polyester, polycarbonate, polyvinyl chloride (PVC) and blends thereof. The thermoplastic materials may also be modified or reinforced with fillers, fibers, flame retardants, colorants, etc.
[0050] An advantage of the present invention is that the thermoplastic material that is immediately adjacent to the vibrating source may not melt and may therefore retain most, if not all, of its' original properties, in other words, not be subjected to a heat history which might detract from its' original properties.
[0051] When a previously molecularly oriented material or, alternatively, materials capable of being molecularly oriented are used, the molecular orientation of the material entering into the cavities may be maintained, increased or reduced by altering the vibration energies applied
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[0053] In addition, if the shrinkage attributable to orientation prior to exposure to vibrational energy is of a given value (S.sub.1), in a given direction in said substrate, the shrinkage (S.sub.2) that may exist after exposure to vibrational energy, in the same direction in the projection may be at least 50% of its original value, or higher (e.g. 150%). That is, S.sub.2.gtoreq.0.50(S.sub.1). Reference to shrinkage herein may be understood as the loss in dimension that will occur when the substrate is heated to a temperature above which the orientation will relax and generally disappear. As noted herein, this may be above the glass transition temperature (Tg) for an amorphous polymer or about the melting point (Tm) for a crystalline polymer.
[0054] In addition, it is contemplated herein that one may start with a substrate that contains little or no orientation, which may be understood as that situation where the shrinkage is less than or equal to 5.0% in any given direction. It may also be characterized as that situation where the Elmendorf Tear strength in a given machine direction (ET.sub.MD) is approximately equal to the Elmendorf Tear (ET.sub.CD) in a given cross direction, with respect to a given substrate. Cross-direction may be understood as that direction, e.g., that is transverse to a machined direction (MD). That is, ET.sub.MD is within about +/−20% of ET.sub.CD. Elmendorf tear strength may be measured by ASTM D1922 and may be understood as the average force required to propagate tearing through a length of the substrate at issue. Accordingly, for such substrate that contains little or no orientation, the application of vibrational energy and the formation of a projection for mechanical engagement may provide a projection that includes orientation, relative to the generally non-orientated substrate from which it was formed. The orientation in such projection may be such that it includes shrinkage in a given direction of greater than 5.0%.
[0055] Furthermore, it is contemplated herein that one may start with a substrate that has biaxial orientation, which may be understood as that situation where there is orientation in both the machine and cross-directions. For example, the machine and cross-direction may indicate relatively uniform shrinkage values of greater than 5.0%. It may therefore be appreciated that upon formation of a projection for mechanical engagement, the underlying substrate will now substantially retain the biaxial orientation, due to the ability to focus the vibration energy at the surface of the substrate, to form the projection, without substantially disturbing the underlying biaxial orientation present in the substrate.
[0056] It should also be noted that with respect to the properties of the substrate and projection noted above, one or more of such properties may be present in any given substrate/projection configuration.
[0057] In the case where a multilayered material (laminate) may be utilized, a portion of one or more or the layered materials may be formed into the cavities allowing for the production of a product where the properties of the hook portion may be selectively engineered.
[0058] Where a multilayered laminate is utilized, the fastener elements may be produced from one or more colors and the strip-like base may be of a different color(s). In addition, if a multilayered laminate is utilized having a transparent surface layer, the fastening elements or the strip-like material may be formed to be transparent.
[0059] Unlike prior art taught in this field where raw material is converted to a molten state prior to forming a substrate in web form to include integral projections, the present disclosure allows the substrate material to retain such desirable properties as molecular orientation, multicolored layers or composite structures by softening the polymer and forming it into the desired shape using vibratory energy, thereby also minimizing the thermal history of the polymer(s) processed.
[0060] With reference to
[0061] In some instances, an after-burst of ultrasonic energy may be applied during or after cooling has taken place to aid in “decoupling” the projections from the mold or horn. This may be particularly useful when the projections are formed in the surface of the source of energy, i.e. the horn.
[0062] One example of a process for providing projections on a substrate which may be used as one of the mating portions in a touch fastening system is shown in
[0063] Power may be applied (Block 500) to the source of vibration to selectively soften the substrate material and allow material into the cavities in the molding roll, forming projections. Alternatively, the molding roll may be smooth and the cavities for forming the projections may be formed into the surface of the source of vibration as depicted in
[0064] The projections, and substrate, if required, may be cooled and the substrate including projections extending from the surface thereof may be stripped from the molding roll to form a strip for use in a touch fastener system. Cooling make take place between the molding roll and the source of vibration, in the molding roll or on the substrate after release from the roll. The projections may subsequently be post-formed into a desired shape.
[0065] As described herein, the cavities for forming the projections may be also be formed in the surface of a rotating horn (see
[0066] Although hook-shaped cavities and hook-shaped projections are referenced herein, it is anticipated that cavities may be chosen to produce projections having other shapes which may function as the “hook” portion of a touch fastener system including, but not limited to, straight pins, angled pins, tapered pins, mushroom headed pins and curved pins, as well as elements with varying cross-sections such as, but not limited to round, oval, square, rectangular, trapezoidal, cross, multi-lobed, grappling hook, multi-limbed or combinations of these. The projections may have a solid core or may be in hollow form such as tubular. Examples of some of these shapes are shown in
[0067] The surfaces of the vibrating source 13 may be shaped so as to increase the length of time thermoplastic materials may be subjected to the vibration energy or to otherwise improve the properties and/or performance of the process.
[0068] In another exemplary embodiment, as shown in
[0069] In another exemplary embodiment, as shown in
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[0071] In another exemplary embodiment, as shown in
[0072] In another exemplary embodiment, as shown in
[0073] In still another exemplary embodiment, two or more sources of vibration, either stationary or rotary in nature, may be utilized simultaneously.
[0074] As described above, the process and apparatus according to the present disclosure is suitable for forming a product having projections which may function as hook fasteners or projecting elements having other shapes in touch fastening systems on one or more surfaces of a strip of thermoplastic material substrate, the substrate comprising film, sheet, web, composite, laminate or other form, or from portions thereof. The substrate may include a cellular structure, such as a foamed polymer, for example, or be a molecularly oriented film or a composite that may, for example, include a fibrous reinforcement. The projections may have a variety of shapes, lengths and dimensions. The projections may be formed from one or more of the materials making up the multilayered film or substrate sheet or portions of such.
[0075] It is contemplated that at least a portion of the substrate may comprise a thermoset polymer.
[0076] It is further contemplated that the substrate upon which the projections are formed may include continuous or intermittent layers of materials and combinations thereof. For instance, it is contemplated that projections may be formed on an intermittent web, to produce diaper closure tabs, possibly inline with a diaper manufacturing machine.
[0077] It is further contemplated that projections may be formed in their final shape or produced partially shaped and post-formed to obtain their final geometry, for instance, a straight pin that may be reshaped into a hook shape, or a straight pin that may be blunted into a mushroom shape in a subsequent processing step or a deformed hook that may be post-formed into a hook capable of functioning as a fastening element.
[0078] It is further contemplated that the projections as formed herein may provide a means of fastening, either temporary or permanent, by engaging with a material having loop elements (e.g. structures that will mechanically engage a projection such as a hook), or engaging to screen-like materials, open-celled foam-like materials or a material having similar or mating projections (for instance, hooks, mushrooms, etc.)
[0079] In a particular advantage of the process described herein, the projections of the present disclosure may be formed intermittently on a substrate by turning the source(s) of vibration on and off as desired or by intermittently altering the position and/or contacting force and/or vibration frequency of the vibrating source. For example, one may move an ultrasonic horn or other vibration source up and down intermittently while a web passes through the process to intermittently form projections on a substrate. As such, projections may be formed in a desired pattern, and the pattern may be varied during the in-line processing of the substrate. Accordingly, the projections may be of uniform height or multilevel height depending on the conditions of operation of the apparatus.
[0080] Projections, according to the present disclosure may be formed on a substrate, such as a web, with portions of the web formed to be creped or folded to allow the web to stretch.
[0081] In another exemplary embodiment, projections may be formed while simultaneously attaching them to an extensible or non-extensible web. As shown in
[0082] Further, a pattern of projections may be formed by passing a pre-perforated or pre-die cut masking material between the substrate (film, sheet, composite, etc.) and molding roll thereby selectively covering areas of the molding roll and providing an intermittent pattern of projections. The mask may be removed (
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[0087] In addition, it is contemplated that projections may be formed through openings in covering layers of material by passing multiple layers of material between a molding roll and vibration source where the covering layer may include holes that align with the pattern of cavities in one or more of the rolls, or where porous materials, such as textiles, may provide openings for the substrate material to be forced through and into the cavities in the roll(s), or where the strength of the covering layer is sufficiently weak such that a substrate material may burst through the covering material and into the cavities of the mold.
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[0089] Further, a laminate of multiple layers, for instance, thermoplastic substrate/fabric/thermoplastic fabric may be passed between cooperating rolls/vibration sources (see, for instance,
[0090] It is further contemplated that intermittent cuts or slits or other wise shaped apertures may be produced in the substrate by raising portions of the molding roll surface (or rotary horn surface) to create cuts or very thin portions of the substrate. These modifications to the substrate may serve to make the fastening strip softer and/or stretchable and/or breathable.
[0091] The process and apparatus as described herein may provide advantages over an extrusion/molding process as relatively less heating and cooling energy may be consumed since only the material used to form the projections may be heated and cooled. Further, multiple colors may be provided by the choice of substrate material and a broad variety of properties may be obtained through the selection of substrate materials, including but not limited to, molecularly oriented substrates or composite substrates. Materials that have printed patterns, logos, etc., may be used as substrates and thereby have projections formed into one or more of their surfaces allowing the printed patterns, etc. to remain legible. Start-up time for the process may be relatively fast and the process may be started and stopped at will, eliminating the need for complex and costly automated transfer winders, as are often required in continuous extrusion processes. Finally, floor space may be reduced substantially.
[0092] Touch fasteners are often adhered to various thermoplastic objects. One such application involves the attachment of touch fasteners to automotive door panels and interior headliner panels. The materials chosen for use as touch fasteners (polyamides, polyolefins, etc.) often make adhesive bonding difficult, expensive and a common source of failure. It is contemplated that a version of the process and apparatus described herein may eliminate or reduce the need for adhesives to bond fasteners to base materials as the hook-type fasteners (projections) may be formed as part of or formed onto the surface of such base materials.
[0093] The processes and apparatus described heretofore are primarily directed at continuous or semi-continuous methods of forming projections on various surfaces. In another exemplary embodiment, which may be described as “plunge forming”, the projections may be formed anywhere on a thermoplastic object using automatic equipment, a robotically held or hand-held horn, or other source of vibration, which may be brought to the location where the projections are desired to be formed.
[0094] In some instances, an after-burst of ultrasonic energy may be applied during or after cooling has taken place to aid in “decoupling” the projections from the mold or horn. This may be particularly useful when the projections are formed in the surface of the source of energy, i.e. the horn. It is contemplated that a removable or replaceable horn tip may be used to allow relatively rapid changing of the pattern of projections.
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[0096] In another exemplary embodiment, as shown in
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[0098] The process and apparatus described herein may greatly reduce the complexity of insert molding hook type materials into larger molded objects as different types of materials may be fed in layers to the apparatus and the projections formed on or through one or more of the layers. Materials for a portion of the substrate layer or for the projections may thus be different from the substrate materials. The use of an ultrasonic horn or other source of vibration energy and the use of a mold-like base as disclosed herein to form projections on objects in a discontinuous or intermittent process or to locally form a pattern of projections on the surface of an object, may provide relatively lower capital and space requirements as well as a very flexible process capable of being easily moved. It is contemplated that all of the features disclosed regarding the continuous or semi-continuous process herein also may apply to the local application of projections on an object.
[0099] The projections disclosed herein for use as elements in a touch fastening system may be produced in a relatively wide range of sizes and densities to provide a wide range of fastening or holding strength. While not being held to any particular limits, it is contemplated that the height of such projections may range from less than about 10 microns to greater than about 5 mm.
[0100] The description and drawings illustratively set forth the presently preferred invention embodiments. The description and drawings are intended to describe these embodiments and not to limit the scope of the invention. Those skilled in the art will appreciate that still other modifications and variations of the present invention are possible in light of the above teaching while remaining within the scope of the following claims. Therefore, within the scope of the claims, one may practice the invention otherwise than as the description and drawings specifically show and describe.