Hook structure for integrally molded surface fastener

Abstract: Hook elements (2) of a surface fastener can intermesh reliably with the loop elements of a companion surface fastener and can be unfastened from the loop elements very smoothly. The integrally molded hook element (2) has softness and strength similar to those of monofilamentary hooks of a woven surface fastener.

Description: This invention relates to an integrally molded surface fastener member comprising (a) a flat base; and (b) a plurality of hook elements in rows extending from said flat base, each said hook element including (i) a back extending from said flat base with a gradual slope, (ii) a front extending at least partially upright from said flat base, (iii) a standing portion, and (iv) a hook head extending forwardly from said standing portion, each said hook element having a varying cross sectional area increasing gradually from said hook head toward said flat base. There are currently known a variety of surface fasteners including hook elements which are made of woven and cut monofilaments. Such surface fasteners are characterized by the softness of fabrics and monofilaments, thereby assuring strong fastening with and smooth unfastening from a mating pile surface. Further, the monofilaments undergoing an elongation process have excellent tensile and bending strength even when the monofilaments are very thin. Monofilamentary hooks can be spaced very densely according to textile weave, thus causing very reliable fastening and being durable in repeated use. Partly since materials for such woven surface fasteners are very expensive and partly since they are made through a number of manufacturing processes, it is very difficult to reduce the manufacturing cost. To overcome the above inconvenience of the woven surface fasteners, integrally molded surface fasteners have been developed, in which hook elements integrally extend from a base by extrusion or injection molding. An integrally molded surface fastener member of the type mentioned above is disclosed in US-A-4.725.221. In this conventional surface fastener the standing portion of each hook element has a substantial elliptic cross sectional shape. The positional relationship between adjacent hook elements in each row is not disclosed. Hook elements in integrally molded surface fasteners cannot be shaped as delicately as those of woven surface fasteners. Molded hook elements do not have sufficient molecule orientation. Therefore when it is as thin as a monofilament, each hook element is too weak to be applied for practical use. The hook element should be inevitably large so as to be strong enough. In such a case, the hook element becomes not only too rigid but also the number of the hook elements per unit area (density of the hooks) is reduced, resulting in weaker intermesh with koop elements of the companion fastener member. To compensate for this inconvenience, when the tips of the hook elements are made rigid, fastening and unfastening become somewhat unsmooth and stiff. In addition, the loop elements on the companion surface fastener member may be damaged, cut or worn out easily. Therefore, surface fasteners of this type are used only for installing interior finish materials for which repeated fastening and unfastening is not carried out frequently, for example. It is therefore an object of this invention to provide a novel structure of hook elements which can assure smooth fastening and unfastening, very strong intermesh and reliable operation for a long period of time similar to woven surface fasteners. According to this invention there is provided an integrally molded surface fastener member of the type mentioned above, characterized in that at least one side of said standing portion of each of said hook elements is provided with a reinforcing rib extending from said flat base and that the furthermost forward edge of the hook head of each hook element and the end of the sloped back of an adjacent hook element in the same row are aligned substantially perpendicularly with respect to said base. The front of each hook element extends upright from the base while its rear is gradually sloped. The hook element has a pair of reinforcing ribs on its opposite sides. Since the sectional area of the hook element is increased gradually from its head toward its root, the whole hook element is deformed resiliently when it is unfastened from a mating loop element. In addition, since it receives unfastening force at its thickest portion, the hook element is protected against breakage, assuring smooth unfastening. The reinforcing ribs are provided so as to protect the hook element against transverse bend. When fastened, each loop element of the companion surface fastener is guided along the sloped back of one hook element, being made to intermesh an adjacent rear hook element reliably and strongly. Specifically, when a furthermost forward edge of the hook head of one hook element is aligned perpendicularly above the sloped end of the hook element in front of the first-mentioned hook element, the ratio of intermesh between the hook elements and loop elements can be further increased. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary side elevational view, partially in cross section, showing hook elements in an integrally molded surface fastener; FIG. 2 is a fragmentary front elevational view of the surface fastener of FIG. 1; FIG. 3 is a fragmentary front elevational view of another surface fastener; FIG. 4 is a plan view of the hook elements in the direction of the arrow III of FIG. 1; FIG. 5 is a plan view of the hook elements taken along line IV-IV of FIG. 1; FIG. 6 is a plan view of a modified surface fastener ; FIG. 7 is a fragmentary side elevational view of a further modification of the surface fastener; and FIG. 8 is a plan view of the modification of the surface fastener of FIG. 7. DETAILED DESCRIPTION This invention will now be described with reference to embodiments shown in the accompanying drawings. FIG. 1 is a fragmentary side elevational view of typical hook elements of a surface fastener. In FIG. 1, reference numeral 1 stands for a flat base, on which a plurality of hook elements 2 protrude in rows. A number of rows are juxtaposed on the base 1. Two rows A and B of the hook elements are shown in FIG. 1. The hook elements on the rows A and B face opposite directions. Both the base 1 and the hook elements 2 are made of thermoplastic resin by either extrusion or injection molding as described above. Each hook element includes a portion 21 extending from the base 1 (hereinafter referred to as a standing portion 21) and a downward hook head 22 at the forward end of the standing portion 21, looking like the crest of a wave in cross section. A back 23 of the standing portion 21, i.e. a side opposite to the hook head 22, is sloping gently from the base 1. A front 24 of the hook element is rounded at its bottom, extending upright from the base 1. The standing portion 21 fans out toward the base 1 in side cross section outline. A pair of reinforcing ribs 21a are formed integrally with the base 1. The ribs 21a are shaped as desired. Typical examples of the ribs 21a are shown in FIGS. 2 and 3. As viewed from the front side of the hook elements, the ribs 21a have a substantially uniform width from the bottom to the top in Fig. 2. The ribs 21a shown in FIG. 3 are tapered toward their tops. The hook head 22 is at the forward end of the standing portion 21, forming a space 25 between its underside and the front 24. The hook head 22 is slightly tapered toward its forward edge 26. In other words, the hook element 2 is enlarged gradually from the forward edge 26 to the bottom 27 of the standing portion 21. When the hook elements 2 of the surface fastener member are pressed to loop elements of a non-illustrated companion surface fastener, some loop elements are guided along the sloped backs 23 of the hook elements while some loop elements are guided to the forward edges 26 of the hook heads 22. The former loop elements intermesh the hook heads 22 of the hook elements 2 adjacent to the sloped backs 23. The latter loop elements grip the hook heads 22. In either case, the hook elements 2 and the loop elements of the surface fasteners fasten reliably one another. In the embodiment shown in FIG. 1, the furthermost forward edge 26 of the hook head 22 of one hook element and the end 28 of the sloped back 23 of an adjacent hook element are aligned substantially along the same perpendicular line, thereby enabling the hook elements and the loop elements to intermesh further reliably. The reinforcing ribs 21a prevent the hook elements from bending transversely when the hook elements are pressed to the loop elements repeatedly. Since each hook head 22 is tapered toward its forward edge so as to be flexible, each hook element can be unfastened from the loop element smoothly. In addition, the above-mentioned structure of the standing portion 21 enables the hook element to absorb at its bottom an excessive unfastening force applied to the hook head 22, thereby allowing the standing portion 21 to regain its original posture resiliently, and releasing quickly the loop element from the hook head 22. FIG. 6 shows an example of a modified hook element 2 whose standing portion is lengthened. Since such hook elements 2 tend to bend transversely, standing portions of the hook elements 2 in adjacent rows A and B are interconnected by reinforcing ribs 3, 3 as shown in FIG. 6. This example differs from those described above in the point. The ribs 3, 3 assist in reinforcing the standing portions as a whole. Therefore it is possible to thin the other parts of the hook elements, thereby making it possible to space the hook elements more densely. The surface fastener thus formed become more similar to the woven surface fasteners. In an example shown in FIGS. 7 and 8, the standing portions 211 except for the backs 213 are straight, the ribs 30 are made tall, and a space between adjacent two hook elements 20, 20 is narrowed. This is because the hook elements can be thinned due to existence of the reinforcing ribs 30. Therefore the hook elements can be spaced closely, allowing the hook heads 212 to intermesh with the loop elements more easily. Even when the front 214 of the standing portion 211 is straight, the hook head 212 will not be damaged or broken. The hook elements having the structure described above can intermesh reliably with the loop elements of a companion surface fastener element, and can be unfastened from the loop elements very smoothly. The entire hook element can receive resiliently instant forces applied at the time of fastening and unfastening, being protected against breakage. The reinforcing ribs enable the hook elements to be used reliably and repeatedly. Further, the surface fasteners according to this invention can fasten and unfasten smoothly the mating loop elements similar to woven surface fasteners. When the standing portions of the hook elements in adjacent rows are inter-connected via the reinforcing ribs, the hook elements can be not only strengthened but also be thinned, so that the hook elements can be spaced densely, enabling easy and reliable intermesh with the loop elements of the companion surface fastener. The integrally molded surface fastener according to this invention can function in a manner similar to woven surface fasteners.

Claims: An integrally molded surface fastener member comprising: (a) a flat base (1); and (b) a plurality of hook elements (2) in rows extending from said flat base (1), each said hook element (2) including (i) a back (23) extending from said flat base (1) with a gradual slope, (ii) a front (24) extending at least partially upright from said flat base (1), (iii) a standing portion (21), and (iv) a hook head (22) extending forwardly from said standing portion (21), each said hook element (2) having a varying cross sectional area increasing gradually from said hook head (22) toward said flat base (1) characterized in that at least one side of said standing portion (21) of each of said hook elements (2) is provided with a reinforcing rib (21a) extending from said flat base (1), and that the furthermost forward edge (26) of the hook head (22) of each hook element (2) and the end (28) of the sloped back of an adjacent hook element in the same row are aligned substantially perpendicularly with respect to said base. An integrally molded surface fastener member according to claim 1, wherein said hook elements (2) arranged on at least two adjacent rows are inter-connected at said standing portions (21) thereof via said reinforcing ribs (21a). An integrally molded surface fastener member according to claim 1, wherein each said reinforcing rib (21a) has a varying cross sectional area increasing gradually from said hook head (22) toward said flat base (1).

Inventors: MURASAKI RYUICHI, YOSHIDA HIROSHI, MURASAKI, RYUICHI, YOSHIDA, HIROSHI
Applicants: YOSHIDA KOGYO KK, YOSHIDA KOGYO K.K.
Application year: 1991
Main classification: A44B18
IPC codes: A44B18