HEAT-SEALABLE STRINGER TAPE FOR SLIDE FASTENERS

Abstract: A heat-sealable stringer tape (11) comprises a major portion (14) which is heat-sealable and a marginal portion (13) which extends along one longitudinal edge of the major portion (14). The stringer tape (11) is a warp-knitted fabric and comprises a knit ground structure arranged over the entire width of the stringer tape (11). The stringer tape (11) also includes a plurality of thermoplastic filament yarns (L4) arranged in the major portion.

Description: The present invention relates generally to a slide fastener and more particularly to a heat-sealable slide fastener stringer tape which can be heat-sealed to a garment made of thermoplastic synthetic resin. A slide fastener is usually attached to a garment by sewing. However, where a garment is made of synthetic resinous sheets such as vinyl chloride sheets, a needle is difficult to pass therethrough. Furthermore, where the thus stitched garment is subjected to severe lateral severe forces, the synthetic resinous garment is inclined to be torn along the stitching. With such a difficulty in view, a heat-sealable slide fastener stringer tape has been proposed which tape comprises a woven fabric coated on its one surface with thermoplastic resin. When attaching such a heat-sealable stringer tape to the garment, the heat-sealable stringer tape and the garment are overlapped on each other and pressed together under heat, so that the thermoplastic resin liquefies to thus unify the garment and the stringer tape. Although this proposal has been satisfactory in attaching the stringer tape to the garment with increased stability, this coated stringer tape is disadvantageous in that it is expensive because coating is rather time-consuming. In order to solve the problem, another type of heat-sealable stringer tape has been proposed as disclosed in Japanese Utility Model Publication No. 59-29527. The disclosed heat-sealable stringer tape is a woven stringer tape employing thermoplastic synthetic resinous yarns as the warp threads while non-thermoplastic yarns are used as the weft threads. Since the themoplastic synthetic resinous yarns are incorporated into the stringer tape as the stringer tape is being woven, this heat-sealable woven tape is less expensive, indeed. Furthermore, since a predetermined region of the stringer tape is almost entirely occupied by the thermoplastic synthetic resinous yarns, the stringer tape can be attached to the thermoplastic resinous garments firmly. However, the disclosed stringer tape has a disadvantage in that, since the thermoplastic synthetic resinous yarns are employed as the warp threads, the thermoplastic yarns, as soon as fused, will become reduced in thickness and sometimes become torn, thus being liable to cause the stringer tape as a whole to lose the required strength. US-A-2 470 251, on which the preamble of claim 1 is based discloses a stringer tape comprising a first longitudinally-extending portion which is heat-sealable and a second longitudinally-extending portion which is not heat-sealable, said first and second portions being disposed in side-by-side relationship to each other. However, the stringer tape disclosed in US-A-2 470 251 is a woven fabric, with thermoplastic yarns forming part of the fabric. Therefore, this stringer tape suffers from the same disadvantages as does the stringer tape disclosed in JP-Y-59-29527. FR-A-2 197 538 discloses a stringer tape of a warp-knitted structure which contains thermoplastic yarns. However, FR-A-2 197 538 is not directed at a heat-sealable stringer tape. In the stringer tape of FR-A-2 197 538 thermoplastic yarns are arranged as wefts, extending over the full width of the stringer tape. The thermoplastic yarns form part of the fabric of the stringer tape. This stringer tape therefore suffers from the same disadvantages as does the stringer tape disclosed in JP-Y-59-29527. With the foregoing difficulties in view, it is therefore, an object of the present invention to provide a heat-sealable stringer tape for slide fasteners which is entirely free from the disadvantages which the conventional stringer tapes have encountered. Another object of the present invention is to provide a heat-sealable stringer tape for slide fasteners which can be heat-sealed to a garment made of thermoplastic synthetic resin firmly and easily. Still another object of the present invention is to provide a heat-sealable stringer tape for slide fasteners which can be manufactured with less cost. Yet another object of the present invention is to provide a heat-sealable stringer tape for slide fasteners which can be heat-sealed to a garment made from thermoplastic synthetic resin without the risk of causing the stringer tape to lose its required strength. According to the present invention there is provided a stringer tape comprising a first longitudinally-extending portion which is heat-sealable and a second longitudinally-extending portion which is not heat-sealable, said second portion extending along one longitudinal edge of said first portion; said stringer tape being characterised in that it is a warp-knitted fabric; in that the entire width of the stringer tape comprises a knit ground structure, said knit ground structure comprising a plurality of chain stitches extending in a longitudinal direction to form a plurality of wales and at least one weft extending in a transverse direction over the entire width of the stringer tape; in that a plurality of thermoplastic filament yarns are provided in the first portion of the stringer tape, said plurality of thermoplastic filament yarns being additional to said knit ground structure; and in that said first portion of the stringer tape is a major portion and said second portion of the stringer tape is a marginal portion. Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which preferred structural embodiments incorporating the principles of the present invention are shown by way of illustrative example. FIG. 1 is a schematic diagram showing the patterns of a plurality of yarns in a warp-knitted heat-sealable stringer tape according to a first embodiment of the present invention; FIG. 2 is a diagram showing the guide bar movement for the yarns shown in FIG. 1; FIG. 3 is a fragmentary plan view of a pair of slide fastener stringers each including a slide fastener stringer tape according to the first embodiment of the the present invention; FIG. 4 is a lateral cross-sectional view of the slide fastener stringers of FIG. 3, but as attached to the respective garment fabric pieces; FIG. 5 is a schematic diagram showing the patterns of yarns in a warp-knitted heat-sealable stringer tape according to a second embodiment of the present invention; FIG. 6 is a schematic diagram showing the patterns of yarns in a warp-knitted heat-sealable stringer tape according to a third embodiment of the present invention; FIG. 7 is a diagram showing the guide bar movement for the yarns shown in FIG. 6; and FIG. 8 is a schematic diagram showing the patterns of yarns in a warp-knitted heat-sealable stringer tape according to a fourth embodiment of the present invention. FIG. 4 shows a pair of slide fastener stringers 10, 10, each including a heat-sealable stringer tape 11 and a row of coiled coupling elements 12 formed from a monofilament and sewn onto the stringer tape 11 along one longitudinal edge thereof. The heat-sealable stringer tape 10 comprises a major portion 14 and a longitudinal marginal portion 13 extending along one longitudinal edge of the major portion 14 and adapted for mounting the coupling elements 12 thereon. As shown in FIG. 1, the stringer tape 11 is of warp-knitted fabric and includes a knit ground structure arranged over the entire width thereof. As better shown in FIG. 2, the knit ground structure comprises a plurality of chain stitches L1 knitted in a pattern of 1-0/0-1 to form a plurality of wales, a first laid-in weft yarn L2 laid in a pattern of 0-0/11-11 and a second laid-in weft yarn L3 laid in a pattern of 11-11/0-0 to join the wales in every course. The first laid-in weft yarn L2 and the second laid-in weft yarn L3 extend transversely over the full width of the stringer tape 11 and are laid in symmetrical relation to each other. Yarns 16 forming the chain stitches L1, and the first and second laid-in weft yarns L2, L3 are all polyester textured yarns. The chain-stitch-forming yarn 16 and either of the first and second laid-in weft yarns L2, L3 have thickness of 150 denier, while the other laid-in weft yarn L3, L2 has thickness of 300 denier. As shown in FIG. 1, the major portion 14 further includes a plurality of (seven in this embodiment) thermoplastic filament yarns made from polyvinylchloride and laid as laid-in warp yarns L4. These laid-in warp yarns L4 are laid in a pattern of 0-0/0-0 to fill the inter-wale grooves interposed between each adjacent ones of the fourth through the eleventh wales and to extend lineally along the wales. The provision of the thermoplastic filament yarns as the warp yarns L4 advantageously permits the stringer tape 11 to be heat-sealed to a thermoplastic garment 15. The thermoplastic warp yarn L4 is 220 denier thick and is lower in fusing point than the chain stitches L1 and the first and second laid-in weft yarns L2, L3 made of polyester textured yarns. As a result, when the stringer tape 11 is subjected to high frequency welding, the thermoplastic warp L4 liquefy and functions to firmly fuse the stringer tape 11 and the thermoplastic garment 15. Since the warp yarns L4 extend rectilineally along the wales, the amount of the thermoplastic filament yarns constituting the warp yarns L4 can be reduced, thus helping to economize the cost of the stringer tape as a whole. FIG. 5 shows a second embodiment of the present invention. The only difference which makes the second embodiment differ from the preceding one is that the major portion 14 (which could be also referred to as an intermediate portion in this embodiment) of the stringer tape 21 has another or second marginal portion 13' provided along the other longitudinal edge of the major portion 14. The second marginal portion 13' is identical in structure with the first marginal portion 13. This results in the stringer tape 21 in this embodiment being disposed symmetrical relative to the longitudinal axis of the stringer tape 21. In this embodiment, the first laid-in weft yarn L2 is laid in a pattern of 0-0/14-14, while the second laid-in weft yarn L3 in a pattern of 14-14/0-0. Since there are the longitudinal marginal portions 13, 13' on both longitudinal edges of the stringer tape 11, either of which is available for carrying the coupling elements 12; when mounting the fastener elements 12 on the stringer tape 11, an operator need not choose one longitudinal edge along which the marginal portion 13 exists. Therefore, the stringer tapes 11 are very easy to handle in the operation of mounting fastener elements 12 thereon, thus resulting in enhancement of the manufacturing efficiency of the slide fastener as a whole. FIG. 6 shows a third embodiment of the present invention. A heat-sealable stringer tape 31 according to the third embodiment is substantially identical with the stringer tape 21 according to the preceding embodiment with the only exception that the major portion 14 includes a plurality of laid-in warps L4' are laid over the fourth through the eleventh wale in a pattern of 1-1/0-0. Each of the laid-in warp L4' extends longitudinally and meandrously on and along the respective wales, so as to expose themselves on the front surface of the stringer tape 31. This enhances the adhesive strength to heat-seal the stringer tape 31 to the thermoplastic garment 15 under heat and pressure. FIG. 8 shows a fourth embodiment of the present invention. A heat-sealable stringer tape 41 according to the fourth embodiment is substantially identical with the stringer tape 11 according to the second embodiment with the only exception that the major portion 14 includes a plurality of laid-in warps L4'' laid over the third through the twelfth wale in a pattern of 2-2/1-1/0-0/1-1. Each of the laid-in warps L4'' extends meandrously between each adjacent wales to join the wales. Since extending meandrously between each adjacent wales, the laid-in warps L4" have been advantageously reduced in number while they can still maintain the commensurate adhesive strength. Although the warp knitted stringer tapes 11, 21, 31, 41 are knitted by a crochet machine in the illustrated embodiments, they can be also knitted by a russell machine or a tricot knitting machine. Furthermore, in all the illustrated embodiments, the chain stitches L1 are of closed type, nevertheless, open type chain stitches in a pattern of 0-1/1-0 can be employed instead. The longitudinal marginal portion 13 of the stringer tape 11, 21, 31, 41 may be reinforced by laying an additional laid-in weft thread (not shown) therein over the three wales thereof. With the structure of the present invention set forth above, the following advantages are enjoyed. Since the heat-sealable filament yarns laid in the form of laid-in warps are independent in structure from the knit ground structure, the fusion of the heat-sealable filament yarns for the purpose of attaching the stringer tape to the garment will never damage the knit ground structure. Furthermore, the laid-in warp yarns can be laid at various positions and in various patterns in order to satisfy the required adhesive strength with which the stringer tape is heat-sealed to the garment. Obviously, various modifications and variations of the present invention are possible in the light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

Claims: A stringer tape (11, 21, 31, 41) comprising a first longitudinally-extending portion (14) which is heat-sealable and a second longitudinally-extending portion (13) which is not heat-sealable, said second portion (13) extending along one longitudinal edge of said first portion (14); said stringer tape being characterised in that it is a warp-knitted fabric; in that the entire width of the stringer tape comprises a knit ground structure, said knit ground structure comprising a plurality of chain stitches (L1) extending in a longitudinal direction to form a plurality of wales and at least one weft (L2, L3) extending in a transverse direction over the entire width of the stringer tape (11, 21, 31, 41); in that a plurality of thermoplastic filament yarns (L4) are provided in the first portion (14) of the stringer tape, said plurality of thermoplastic filament yarns (14) being additional to said knit ground structure; and in that said first portion (14) of the stringer tape is a major portion and said second portion (13) of the stringer tape is a marginal portion. A heat-sealable stringer tape (11) according to claim 1, the thermoplastic filament yarns (L4) being laid rectilineally in and along interwale grooves interposed between each pair of adjacent wales of the knit ground structure. A heat-sealable stringer tape (31) according to claim 1, each of the thermoplastic filaments (L4) is laid to extend meandrously on and along their respective wales so as to expose itself on the front surface of the stringer tape (31). A heat-sealable stringer tape (41) according to claim 1, each of the thermoplastic filament (L4) being laid to extend meandrously between each pair of adjacent wales to join the wales. A heat-sealable stringer tape (21) according to any preceding claim, including a third portion (13' ) which extends along an other longitudinal edge of the major portion (14) and which is identical in structure with said second portion (13) so that the stringer tape (21) is symmetrical relative to a longitudinal axis of the stringer tape (21). A heat-sealable stringer tape (11, 21, 31, 41) according to any preceding claim, the chain stitches (L1) and the laid-in weft (L2, L3) being made of polyester textured yarns and the heat-sealable filament (14) being made of polychloride vynil which is lower in fusing point than the polyester textured yarns.

Inventors: IKEGUCHI, YOSHITO
Applicants: YOSHIDA KOGYO K.K.
Application year: 1990
Main classification: A44B19
IPC codes: A44B19