Fasteners engageable with loops of nonwoven fabrics and with other open structures, and methods and machines for making fasteners

Abstract

A method of forming a fastener is provided, including (a) forming, from a thermoformable material, a preform product having a sheet-form base and an array of preform stems integrally molded with and extending from the base to corresponding terminal ends; (b) heating the terminal ends of the stems to a predetermined softening temperature, while maintaining the sheet-form base and a lower portion of each stem at a temperature lower than the softening temperature; and (c) contacting the terminal ends with a contact surface that is at a predetermined forming temperature, lower than the softening temperature, to deform the terminal ends to form heads therefrom that overhang the sheet-form base. Fasteners and other methods of forming them are also provided.

Description

[0001]This application is a continuation in part of U.S. Ser. No. 09 / 870,063, filed May 30, 2001, now U.S. Pat. No. 6,708,378, which is a divisional of U.S. Ser. No. 09 / 231,134, filed Jan. 15, 1999, now U.S. Pat. No. 6,248,276. This application is also a continuation in part of U.S. Ser. No. 09 / 808,395, filed Mar. 14, 2001 pending. This application also claims priority fromunder U.S. Provisional Application Ser. No. 60 / 295,937, filed Jun. 4, 2001. The entire contents of each of the foregoing are hereby incorporated by reference.TECHNICAL FIELD[0002]This invention relates to touch fasteners commonly known as hook and loop fasteners and to self-engaging fasteners. In many aspects it deals with the particular case in which hooks engage flexible loops such as are formed of fibers of thin nonwoven materials and the like.BACKGROUND[0003]The present invention relates to male fastener components that engage in openings of a female component, in particular to loops formed by fibers of a nonw...

AI Technical Summary

Benefits of technology

[0020]Preferred methods include one or more of the following features. The contact surface comprises the cylindrical surface of a roll. The contact surface has a sandpaper-like texture. The contact surface has a surface roughness (rugosity) of about 10 to 200 microns. The contact surface defines a plurality of dimples. The contact surface includes a density of dimples per unit area of the contact surface that is greater than or equal to the density of stems per unit area of the base. The surface roughness imparted to the heads is sufficient to increase the peel strength of the fastener by from about 10 to 100%. The contact surface is so related to the thickness and nature of the heads being formed that contact with the upper surface of the heads is effective to transmit the effect through the resin thickness of the heads sufficiently to impart a degree of texture or surface roughness to the peripheral edge of the head or the undersurface of the head or both, in regions contacted by loops during hook-to-loop engagement. Preferably, the contact of the conforming surface with the head imparts discrete depressions distributed in X or Y or both directions and numbering in the range between about 3 and 15 depressions per head.

[0069]In the case of using a heated pressing roll following preheating with convection heating as described, anti-adhering material is provided at the interface between the forming surface and the resin. In preferred embodiments the material comprises a Teflon or other anti-stick coating of the forming surface, injection of water or steam to the interface, or both. In this manner, the speed of operation of the process may be increased while still using developed tooling that employ hot rolls or other heated forming surfaces.

Problems solved by technology

With such materials, effective loop height does not permit transition of loading from the hook head to the hook stem during peeling action, as does occur with expensive loop products that have higher loop height.

Such peeling force on the component causes it to flex and progressively peel from the other.

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