Varying the loop engageability of fastener element arrays

Details Varying the loop engageability of fastener element arrays Varying the loop engageability of fastener element arrays

2000-06-02

2003-04-08

Sakran, Victor (Department: 3677)

Buckles, buttons, clasps, etc.

Including readily dissociable fastener having numerous,...

Having mounting surface and filaments constructed from...

C024S304000, C024S442000, C024S446000, C024S450000

Reexamination Certificate

active

06543099

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to varying the loop engageability of arrays of molded fastener elements, and to the formation of fastener products with exposed grip flanges.
Hook components for hook and loop fastening include a base from which tiny fastener elements (e.g., hook-shaped or mushroom-shaped elements) extend in an array. Hook components with hook-shaped elements may be formed by integrally molding the base and fastener elements in a continuous process employing a mold roll that includes a set of stacked disk-shaped mold plates having fastener-shaped cavities defined at their peripheries, e.g., as described in U.S. Pat. No. 4,794,028 (Fischer), the full disclosure of which is incorporated herein by reference. Hook components may also be injection molded as discrete parts. In the Fischer process, it is generally preferable that the entire molding region of the mold roll include an even distribution of mold cavities, to promote uniform resin flow and molding pressures over the mold roll surface and also to avoid uneven demolding stresses that could distort the fastener. To produce fastener products of the same resin but with different loop engagement characteristics, manufacturers either vary the hook density by changing the spacing between adjacent rows of hooks, or replace the mold plates with others having a different hook cavity shape or in-row spacing.
To form a closure, male fastener elements engage overlying female fastener elements. When the male element is hook-shaped, the fastener element will individually exhibit directional shear strength, i.e., the shear strength in one direction will be significantly higher than in other directions. In some applications it is desirable that the array of fastener elements exhibit bidirectional shear strength, i.e., shear strength substantially equal in each of two opposite directions. To accomplish this, some fastener products include arrays of hooks in which a plurality of rows of fastener elements are arranged so that, in each row, all of the crooks face in the same direction and parallel to the direction of the row, and so that the crooks of adjacent rows face in opposite directions, as shown in FIG.
1
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It is often desirable for a hook and loop fastener to have areas in which there is no engagement or a reduced strength engagement of the two sides of the fastener. Such areas may, for example, be associated with a gripping tab to enable the user to more easily separate the two parts of the fastener.
SUMMARY OF THE INVENTION
The present invention features, in several aspects, an array of hook-shaped fastener elements in which the relative spacing between adjacent hooks varies across the array such that some of the fastener elements are rendered less capable of engagement with loop elements than other fastener elements.
In preferred fastener products, the hook elements are arranged so that some of the hook elements interfere with adjacent hook elements to prevent engagement of the hook elements with loop elements. Advantageously, for fastener products that are molded on mold rolls that include a stack of registered mold plates, e.g., as described in U.S. Pat. No. 4,794,028 (a “Fischer process”), this arrangement can be accomplished by simply adjusting the registration of the mold plates, without the need for other process or tooling changes.
In one aspect, the invention features an array of hook-shaped fastener elements arranged in parallel rows, each fastener element including a stem and a crook extending from the stem in a predetermined direction to a distal tip. The array includes a plurality of rows of fastener elements arranged such that, in each row, all of the crooks face in the same direction and parallel to the direction of the row, and such that the crooks of adjacent rows face in opposite directions. The longitudinal spacing between opposing tips of adjacent hooks of adjacent rows is greater, in a first portion of the array, than the longitudinal spacing between opposing tips of adjacent hooks of adjacent rows in a second portion of the array. As a result, the crooks of the hooks of the first portion of the array are more exposed for engaging loops than the crooks of the hooks of the second portion of the array.
In preferred implementations, the crooks of the hooks of adjacent rows in the second portion of the array overlap each other in side profile to interfere with the ability of the crooks to engage loop elements.
In another aspect, the invention features a fastener product that includes (a) a first fastener component comprising a common base and an array of hook-shaped fastener elements arranged in parallel rows on the common base, and (b) a second fastener element, comprising a common base and a plurality of loops extending from the base for engagement with the hooks. Each fastener element includes a stem and a crook extending from the stem in a predetermined direction to a distal tip, and the array includes a plurality of rows of fastener elements, arranged so that, in each row, all of the crooks face in the same direction and parallel to the direction of the row, the crooks of adjacent rows face in opposite directions. The longitudinal spacing between opposing tips of adjacent hooks of adjacent rows is greater, in a first portion of the array, than the longitudinal spacing between opposing tips of adjacent hooks of adjacent rows in a second portion of the array. As a result, the crooks of the hooks of the first portion of the array are more exposed for engaging loops than the crooks of the hooks of the second portion of the array.
In preferred implementations, the product includes a strip of fastener tabs or a fastener tape.
In some cases, the product includes a personal care product. By “personal care product” as used within this patent application, we mean diapers, training pants, swim wear, absorbent underpants, adult incontinence products and feminine hygiene products.
In another aspect, an absorbent article is provided. The article has a flexible sheet for fitting about the body of a wearer, the flexible sheet having a first waist portion and a second waist portion. A first fastener element is coupled to the first waist portion, having a common base and a plurality of loops extending from the base. A second fastener component is coupled to the second waist portion such that the second fastener component can be brought into contact with the first fastener element when the first waist portion and the second waist portion are fitted about the body of a wearer. The second fastener component has a common base and an array of hook-shaped fastener elements arranged in parallel rows on the common base, with the fastener elements arranged as described above so as to enhance the grippability of the second fastener component.
In another aspect, the invention features a method of forming an array of fastener elements extending from a common base. The method includes providing a mold having a mold surface from which an array of fixed mold cavities extend inwardly. Each mold cavity defines a hook including a stem and a crook extending from the stem in a predetermined direction, with the array including a plurality of rows of cavities arranged such that, in each row, all of the crooks face in the same direction and parallel to the direction of the row, and with the crooks of adjacent rows face in opposite directions. The registration of adjacent rows is adjusted so that the longitudinal spacing between opposing tips of adjacent hooks of adjacent rows in a first portion of the array is greater than the longitudinal spacing between opposing tips of adjacent hooks of adjacent rows in a second portion of the array, such that the crooks of the hooks of the first portion are more exposed for engaging loops than the crooks of the hooks of the second portion. Moldable resin is delivered to the mold, thereby filling the mold cavities and forming the common base. The resin is solidified in the cavities to form the fastener elements, which are then removed from their corresponding fixed mold cavities by

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