Stock material or miscellaneous articles – Structurally defined web or sheet – Including fastener for attaching to external surface
Reexamination Certificate
1999-04-01
2001-01-30
Thomas, Alexander S. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including fastener for attaching to external surface
C428S099000, C024S442000, C024S452000
Reexamination Certificate
active
06180205
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to fasteners, in particular to hook and loop type fasteners.
Arrays of molded male fastener elements, e.g., hooks, are often formed integrally with a sheet-form base, to provide a sheet-form fastener component. This component can then be engaged with a similar component of female fastener elements to form a “hook and loop” fastener. It is desirable that the fastener elements have good strength and toughness, so as to provide strong engagement during repeated use of the fastener. It is, on the other hand, desirable that the sheet-form base be relatively soft and flexible, e.g., to allow the base to flex with a fabric article to which it is attached and to prevent the edges of the sheet-form component from causing discomfort to a wearer.
SUMMARY OF THE INVENTION
The invention features an improved, continuously formed touch fastener product with different portions having different material properties, and methods and apparatus for making such a product.
The invention can provide a fastener having both relatively hard, durable regions and relatively softer, more flexible regions. In one aspect of the invention, such a fastener product is produced by forming, from a cross-linkable polymer, a plurality of molded fastener elements integral with a sheet-form base, and selectively cross-linking regions of the polymer to form the hard, durable regions. The regions that are not cross-linked remain relatively soft and flexible. In another aspect of the invention, such a fastener is produced by forming the hard, durable regions from a first polymer, and joining to the first polymer a second polymer having properties different from the first polymer to form the relatively softer, more flexible regions.
In one aspect of the invention, the invention features a fastener including a sheet-form base member, and, extending outwardly from, and integral with, the base member, a plurality of molded fastener elements. At least a portion of the fastener includes a cross-linkable polymer, and a first portion of the fastener is cross-linked and a second portion of the fastener is not cross-linked or is cross-linked to a degree less than the first portion.
Preferred embodiments include one or more of the following features. At least some of the fastener elements are cross-linked. The base member is not cross-linked. The fastener elements include a cross-linkable polymer and the base member includes a non-cross-linkable polymer, or, alternatively, both the fastener elements and the base include a cross-linkable polymer. The base member has a flexural modulus of less than about 80,000 pounds per square inch (psi), more preferably 10,000 to 60,000 psi, and the fastener elements have a flexural modulus of greater than 80,000 psi, more preferably 80,000 to 120,000 psi. The fastener elements have a flexural modulus that is at least 25% higher than that of the base member, more preferably at least 50% higher. The base has a thickness of less than 0.015 inch, more preferably about 0.001 to 0.005 inch. The cross-linkable polymer is selected from the group consisting of polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), poly(ethylene terephthalate) (PET), polyacrylates, polyamides, thermoplastic elastomers, and mixtures thereof. At least some of the fastener elements are male fastener elements, e.g., hooks. The hooks are cross-linked.
According to another aspect, the invention features a method of making a fastener including (a) forming a fastener comprising a sheet-form base member and a plurality of molded fastener elements extending outwardly from and integral with said sheet-form base member, at least a portion of the fastener being formed from a cross-linkable polymer; and (b) cross-linking the cross-linkable polymer in a manner so that a first portion of the fastener is cross-linked while a second portion of the fastener remains non-cross-linked or is cross-linked to a lesser degree than the first portion.
Preferred embodiments include one or more of the following features. Step (b) is performed using electron beam radiation. The cross-linkable polymer is a thermoplastic elastomer that is capable of increasing at least 25% in flexural modulus upon substantially complete cross-linking. The fastener is formed entirely of a thermoplastic elastomer. The fastener elements are hooks. The hooks are cross-linked during step (b). At least a portion of the base is not cross-linked during step (b).
In yet another aspect, the invention features a method of making a fastener including (a) forming a fastener comprising a sheet-form base member and a plurality of molded fastener elements extending outwardly from and integral with said sheet-form base member, by forming a first portion of the fastener from a cross-linkable polymer, and joining the first portion to a second portion of the fastener that is formed from a second polymer; and (b) at least partially cross-linking the first cross-linkable polymer. The invention further features fasteners made by this method.
According to another aspect of the invention, the invention features a method of making a continuous fastener product having an array of fastener elements extending from a sheet-form base. The method includes: (a) providing a mold roll defining a plurality of fastener element mold cavities extending into the mold roll from the outer circumferential surface of the mold roll; (b) applying a first polymer to a surface of the mold roll and forcing some of the first polymer into the mold cavities, with some of the first polymer remaining on the surface of the mold roll in the form of a film having thickness; (c) with a doctoring blade, removing at least some of the first polymer remaining on the surface of the mold roll after step (b) from the surface of the mold roll to at least reduce the thickness of the film of the first polymer on the mold roll surface; (d) applying a second polymer to the mold roll, the second polymer being compatible with the first polymer and adhering thereto; (e) solidifying the first polymer in the mold cavities to form fastener elements; and (f) removing the fastener elements from the mold cavities.
Preferred implementations of the method include one or more of the following features. In step (c), substantially all of the first polymer that remains on the mold roll after step (b) is removed by the doctoring blade. The first polymer is applied by an extruder. The second polymer is applied by an extruder. The first polymer is cross-linkable and the method includes cross-linking the first polymer after removal from the mold roll. The first polymer is relatively harder than the second polymer. The second polymer is more elastic, when solidified, than the first polymer. The method includes, after step (d), bonding a third polymer to the second polymer.
According to another aspect of the invention, the invention features a method of making a continuous fastener product having an array of fastener elements extending from a sheet-form base. The method includes: (a) providing a mold roll defining a plurality of fastener element mold cavities extending into the mold roll from the outer circumferential surface of the mold roll; (b) applying a first polymer to the surface of the mold roll and forcing some of the first polymer into the mold cavities, with some of the first polymer remaining on the surface of the mold roll in the form of a film having thickness; (c) with a doctoring blade, removing at least some of the first polymer remaining on the surface of the mold roll after step (b) from the surface of the mold roll to at least reduce the thickness of the film of the first polymer on the mold roll surface; (d) applying a tie layer to the mold roll, the tie layer being compatible with and adhering to the first polymer; and (e) applying a second polymer to the tie layer.
Preferred implementations of the method include one or more of the following features. The first and second polymers are different materials. The tie layer comprises an adhesive. The tie layer comprises a polymer.
T
Tachauer Ernesto S.
VanBenschoten Brian J.
Fish & Richardson P.C.
Thomas Alexander S.
Velcro Industries B.V.
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