SLIDE FASTENER WITH SEALING FUNCTION

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC § 119 from German Patent application Ser. No. 102024122100.3 filed on Aug. 2, 2024, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention is related to a slide fastener including: a pair of fastener stringers, each of the pair of fastener stringers including a fastener tape and a fastener element row attached to each of opposing side portions of the pair of fastener stringers; and a slider provided slidably at the fastener element row of each of the pair of fastener stringers for engagement and disengagement of fastener elements. Each of the fastener elements includes a base portion attached to the respective fastener tape and a coupling portion for engagement with another coupling portion of an opposite fastener element, and a groove facing an opposite fastener tape and extending in a tape length direction is formed in the coupling portion of each of the fastener elements. Each of the pair of fastener stringers includes a seal part which is adhered to a surface portion of the fastener tape thereof and which extends beyond an edge portion of the fastener tape into the groove of the fastener element, the seal part of each of the pair of fastener stringers being in sealing abutment when the slide fastener is in an engaged state.

BACKGROUND

A related slide fastener is disclosed in the related art, for example, in U.S. Pat. No. 8,869,356B2. The seal parts which are in sealing abutment in the engaged state of the slide fastener provide a sealing function. Thereby, it may be prevented that fluid passes through the slide fastener. Thus, a slide fastener with a water-tight or air-tight property may be provided. Such slide fasteners have various applications, including clothes, tents, wetsuits, spacesuits, water tanks, etc.

The slide fastener of U.S. Pat. No. 8,869,356B2 creates sealing abutment by receiving the portion of the seal part which extends beyond the edge portion of one of the fastener tapes in the grooves of the coupling portions of the fastener elements of the opposite fastener tape and vice versa when the slide fastener is in the engaged state. Each fastener element has a consolidating block which is received in slots of the fastener elements of the opposite fastener element row to thereby stabilize the pair of fastener stringers in the engaged state. While the consolidating blocks result in some stabilization of the engaged fastener stringers, a rotational force on the fastener elements in a direction perpendicular to the fastener tapes may result in a peeling-off of the fastener elements.

An alternative solution for providing fluid tightness to a slide fastener is presented in EP1388302A1. One surface of each fastener tape is completely covered by a seal part which protrudes over the edge of the fastener tape, and holes are provided along the side portions of the fastener tapes. The fastener elements are injected onto the fastener tapes so that a connecting portion penetrates through the holes thereby fixing the fastener elements on the tape. The holes are a disadvantage for the manufacturing process, as they require an additional manufacturing step, and the injection of the fastener elements needs to be precisely at the position of the holes. Furthermore, the holes may potentially be a source of leakage of fluid through the fastener tapes.

A different solution of a slide fastener with a sealing function is presented in WO2022/043684A1. There, the sealing function is provided by a sealing abutment between an edge portion of one of the fastener tapes and grooves provided in the coupling portions of the fastener elements provided on the opposite fastener tapes and by contact between pressure portions provided on the coupling portions of the fastener elements of the opposing fastener tapes. Such a slide fastener does not have the problem of holes in the fastener tape as in EP1388302A1, and also does not have the problem of a large peeling force being potentially applied to the fastener elements. Further, the pressure portions reduce a gap between a first fastener element on one of the fastener tapes and a second fastener element on the opposite fastener tape in the engaged state of the slide fastener and thereby improve the sealing property. However, the pressure portions are integrally formed with the coupling portions and are therefore made of the same hard material as the fastener elements. Thereby, the sealing due to the contact of the pressure portions may not be perfect.

Due to these problems in the related art, it is therefore an object of the present invention to provide a slide fastener which has a strong sealing function and is robust and durable, and to provide a method for manufacturing the slide fastener.

SUMMARY

According to one aspect of the present application, a slide fastener includes: a pair of fastener stringers, each of the pair of fastener stringers including a fastener tape and a fastener element row attached to each of opposing side portions of the pair of fastener stringers; and a slider provided slidably at the fastener element row of each of the pair of fastener stringers for engagement and disengagement of fastener elements. Each of the fastener elements includes a base portion attached to the respective fastener tape and a coupling portion for engagement with another coupling portion of an opposite fastener element, and a groove facing an opposite fastener tape and extending in a tape length direction is formed in the coupling portion of each of the fastener elements. Each of the pair of fastener stringers includes a seal part which is adhered to a surface portion of the fastener tape thereof and which extends beyond an edge portion of the fastener tape into the groove of the fastener element, the seal part of each of the pair of fastener stringers being in sealing abutment when the slide fastener is in an engaged state. The edge portion of the fastener tape of each of the pair of fastener stringers is located in the groove of the fastener element of the opposite fastener tape respectively, when the slide fastener is in the engaged state.

In the slide fastener, the fastener element may include an upper portion provided on an upper side of the fastener stringer and having an upper base portion provided on an upper tape surface of the fastener tape and a lower portion provided on a lower side of the fastener stringer and having a lower base portion provided on a lower tape surface of the fastener tape. The fastener element may further include a connecting portion connecting the upper and lower portions in an up-down direction perpendicular to the upper and lower tape surfaces and being provided outside the fastener tape at the edge portion thereof.

In the slide fastener, the coupling portion may include upper and lower coupling portions respectively extending from the upper and lower base portions towards the opposite fastener tape. Facing surfaces of the upper and lower coupling portions and a surface portion of the connecting portion form a boundary of the groove.

In the slide fastener, the seal part may cover a side surface portion of the base portion which extends in a direction away from the fastener tape in an up-down direction.

In the slide fastener, the edge portion of the fastener tape may include a core thread.

In the slide fastener, the fastener tape of each of the pair of fastener stringers may include a base sheet which is coated with and/or impregnated by a plastic material which is impermeable to fluid.

In the slide fastener, each of the fastener elements may be made of a polyamide resin, the plastic material may include a first polyurethane and the seal part may include a second polyurethane.

In the slide fastener, the seal part may include a seal edge portion protruding over the fastener tape in a tape width direction and extending parallel to the edge portion of the fastener tape.

According to another aspect of the present invention, a method for manufacturing the slide fastener includes: providing a pair of base sheets for the fastener tape for each of the pair of fastener stringers; covering at least one of upper and lower surfaces of each of the base sheets with a plastic material to thereby obtain the fastener tape for each of the pair of fastener stringers; attaching the fastener element row for each of the pair of fastener stringers to each of the opposing side portions for the pair of fastener stringers; and for the fastener tape for each of the pair of fastener stringers, adhering the seal part to the surface portion of the fastener tape so as to extend beyond the edge portion of the fastener tape into the groove of the fastener element.

In the method, the covering at least one of the upper and lower surfaces of each of the base sheets with the plastic material may include extruding the plastic material onto each of the base sheets. The attaching the fastener element row for each of the pair of fastener stringers to each of the opposing side portions for the pair of fastener stringers may include injecting the fastener elements onto the fastener tape for each of the pair of fastener stringers. The adhering the seal part to the surface portion may include injecting the seal part onto the surface portion of the fastener tape and into the groove of the fastener element.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an upper surface of a fastener stringer of a slide fastener according to an embodiment of the first aspect of the present invention.

FIG. 2 is a perspective view of the fastener stringer of FIG. 1, in which some of the fastener elements are removed for ease of representation.

FIG. 3A is a perspective view of a fastener element of the fastener stringer according to the embodiment.

FIG. 3B is a perspective view of one fastener element and a portion of the seal part of the fastener stringer of the embodiment.

FIG. 4A is a front view of FIG. 3B.

FIG. 4B is a sectional view along the line A-A in FIG. 4A.

FIG. 5 is a side view of the fastener stringer of the embodiment in the front direction.

FIG. 6A is a partial perspective view of an upper side of the slide fastener according to the embodiment of the present invention.

FIG. 6B is a partial perspective view of a lower side of the slide fastener according to the embodiment of the present invention.

FIG. 7 is a flow chart of a method of manufacturing a slide fastener according to the second aspect of the present invention.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a plan view of an upper surface of a fastener stringer 1 and FIG. 2 is a perspective view of the fastener stringer 1 of a slide fastener 100 (see FIGS. 6A, 6B) according to the embodiment of the present invention. The plan view of the lower surface of the fastener stringer 1 is similar to the plan view of the upper surface shown in FIG. 1. As will be explained in more detail with reference to FIGS. 6A and 6B, the slide fastener 100 includes another fastener stringer 1 which is similar to the one shown in FIG. 1 and a slider 60 which is slidably attached to the pair of fastener stringers. The fastener stringer 1 includes a fastener tape 40 and a fastener element row 2 provided at a side portion 42 of the fastener tape 40. The side portion 42 of the fastener tape 40 can be also said as the side portion 42 of each of the pair of fastener stringers 1. The plan view of FIG. 1 shows an upper tape surface 41a of the fastener tape 40. The fastener tape 40 is an elongated member which is long in a tape length direction. The tape length direction is also called a front-back (F-B)-direction within this specification. The front (F)-direction is directed upwards with respect to the paper plane, and the back (B)-direction is directed downwards with respect to the paper plane of FIG. 1. The fastener tape 40 also defines a tape width direction which is perpendicular to the front-back direction. The tape width direction may also be called a left-right (L-R)-direction. The left (L)-direction is directed leftwards with respect to the paper plane of FIG. 1, and the right (R)-direction is directed rightwards with respect to the paper plane of FIG. 1. The fastener tape 40 also defines an up-down (U-D)-direction which is perpendicular to the tape length direction and the tape width direction. The up (U)-direction is a direction perpendicular to the paper plane of FIG. 1 and is directed towards the viewer of the FIG. 1, and the down (D)-direction is directed in the opposite direction to the up-direction.

The fastener tape 40 may include a base sheet of a woven or non-woven material. The upper and/or lower surfaces of the base sheet are coated with a fluid-tight layer. Thereby, the fastener tape 40 may be provided with a fluid-tight property.

The fastener tape 40 includes an edge portion 43 which is an outer boundary of the fastener tape 40. The edge portion 43 includes a core thread 44 which extends in the tape length direction and which has an increased thickness in the up-down direction compared to a thickness in the up-down direction of a tape inner portion 45 of the fastener tape 40. The core thread 44 enables a better fixation of the fastener elements 20 to the fastener tape 40 compared to a fastener stringer 1 without the core thread 44.

The fastener element row 2 includes a plurality of fastener elements 20 which are arranged at a predetermined pitch in the tape length direction at the side portion 42 of the fastener tape 40. The shape of the fastener elements 20 will be explained in more detail below.

The slide fastener 100 further includes a slider 60 (see FIGS. 6A, 6B) provided slidably at the fastener element rows 2 for engagement and disengagement of the fastener elements 20 of the opposing fastener stringers. The fastener stringer 1 may further include upper and lower stops (not shown) which are provided at front and back end portions of the fastener element row 2 in the front-back direction and which limit the movement of the slider 60 in the tape length direction.

The fastener stringer 1 further includes a seal part 50 which is adhered to a surface portion 46 of the fastener tape 40. The seal part 50 includes a seal inner portion 51 which is provided on the fastener tape 40 and a seal outer portion 52 which protrudes beyond the edge portion 43 of the fastener tape 40. The seal part 50 further includes a seal edge portion 53 which is an outer boundary of the seal part 50 outside the fastener tape 40 and which protrudes towards an opposite fastener stringer 1 (see FIGS. 6A, 6B). When the slide fastener 100 is closed, the seal parts 50 of the two fastener stringers are in sealing abutment. Thereby, a sealing function is provided.

In the following, the fastener elements 20 and the seal part 50 will be described in more detail with reference to FIGS. 3A to 5. FIG. 3A is a perspective view of one fastener element 20 of the fastener stringer 1 according to the embodiment without the seal part, to facilitate the description. FIG. 3B is a perspective view of the one fastener element 20 together with a portion of the seal part 50 of the fastener stringer 1 of the embodiment. FIG. 4A is a front view of FIG. 3B, FIG. 4B is a sectional view along the line A-A in FIG. 4A, and FIG. 5 is a side view of the fastener stringer 1 of the embodiment. As one may take in particular from FIGS. 3A to 5, the fastener element 20 includes an upper portion 20a provided on an upper side of the fastener stringer 1, and a lower portion 20b provided on a lower side of the fastener stringer 1. The upper portion 20a includes an upper base portion 21a provided on the upper tape surface 41a of the fastener tape 40. The lower portion 20b includes a lower base portion 21b provided on a lower tape surface 41b of the fastener tape 40. The upper and lower portions 20a, 20b include upper and lower coupling portions 22a, 22b, respectively, for engagement with another upper or lower coupling portion of an opposite fastener element 20. The upper and lower coupling portions form a coupling portion of the fastener element 20. The upper and lower coupling portions 22a, 22b include upper and lower neck portions 23a, 23b extending away from the upper and lower base portions 21a, 21b, respectively, in the tape width direction and having a dimension in the tape length direction which decreases with the extension of the upper and lower neck portion 23a, 23b away from the upper and lower base portions 21a, 21b, respectively. The upper and lower neck portions 23a, 23b are continuous with upper and lower head portions 24a, 24b, respectively, which extend further away from the upper and lower neck portions 23a, 23b, respectively, and which respectively include two protrusions 25a, 25b which protrude in opposite directions in the tape length direction. Thereby, the upper and lower head portions 24a, 24b are bulging in the front-back direction.

The upper and lower portions 20a, 20b are connected by a connecting portion 26 which extends in the up-down direction. The connecting portion 26 is located completely outside the fastener tape 40 and is provided at the edge portion 43 of the fastener tape 40. Facing surfaces of the upper and lower base portions 21a, 21b and an inner surface portion of the connecting portion 26 form a boundary of a gripping portion 31 for gripping the fastener tape 40. In particular, the gripping portion 31 includes a first gripping portion 31a which is in contact with the core thread 44 and a second gripping portion 31b which is in contact with the upper and lower tape surfaces 41a, 41b. The fastener element 20 clamps the fastener tape 40 by the gripping portion 31.

Facing surfaces of the upper and lower head portions 24a, 24b and a surface portion of the connecting portion 26 form a boundary of a groove 27 which extends completely through the coupling portion of the fastener element 20 in the tape length direction and which is open towards the opposite fastener tape 40. The seal part 50 adheres to the surface portion 46 of the fastener tape 40 and extends beyond the edge portion 43 of the fastener tape 40 into the groove 27 of the fastener elements 20. The upper portion of the fastener element 20 further includes an upper frontside portion 28a which faces in the front direction and an upper backside portion 29a which faces in the back direction and which both extend in a direction away from the upper tape surface 41a in the up-direction. The lower portion of the fastener element 20 further includes a lower frontside portion (not shown) which faces in the front direction and a lower backside portion 29b which faces in the back direction and which both extend in a direction away from the lower tape surface 41b in the down-direction. As one may take in particular from FIGS. 3B and 5, the seal part 50 covers upper and lower side surface portions 32a, 32b at the upper, lower, front and backside portions. Thereby, the sealing function of the seal part 50 is further improved.

The seal edge portion 53 extends in parallel with the edge portion 43 of the fastener tape 40 (see in particular FIGS. 1 and 2). Thereby, a very good sealing function may be obtained when the fastener stringers 1 of the slide fastener 100 are in sealing abutment in the engaged state of the slide fastener 100.

As one may take in particular from FIGS. 3A and 5, the groove 27 is located completely outside the fastener tape 40 and does not penetrate through the fastener tape 40. The connecting portion 26 is also located completely outside the fastener tape 40, and is connecting the upper and lower portions 20a, 20b of the fastener element 20 in the vicinity of the upper and lower neck portions 23a, 23b. In a view in the up-down direction, the upper and lower base portions 21a, 21b are located completely within the fastener tape 40 (see in particular FIG. 5).

FIGS. 6A and 6B are partial perspective views of upper and lower sides of the slide fastener 100 according to the embodiment, respectively. The slide fastener 100 includes the pair of fastener stringers 1 described above and the slider 60 slidably provided at the fastener element rows 2 for engaging and disengaging the opposing fastener elements 20 of the pair of fastener stringers 1. The two seal parts 50 of the opposing fastener stringers 1 are in sealing abutment when the fastener elements 20 are in the engaged state to thereby provide a sealing function. In this engaged state, the edge portion 43 of the fastener tape 40 of each of the pair of fastener stringers 1 is located in the groove 27 of the fastener element 20 of the opposite fastener tape 40 respectively.

In FIG. 6A, the upper tape surface 41a of the fastener tape 40 and an upper blade 60a of the slider 60 is visible. In FIG. 6B, a lower tape surface 41b of the fastener tape 40 and a lower blade 60b of the slider 60 is visible.

In FIGS. 6A and 6B, the slide fastener 100 is partially open. When the slider 60 is moved in the front (F)-direction, opposing fastener elements 20 are engaged, and the slide fastener 100 is closed. When the slider 60 is moved in the back (B)-direction, opposing fastener elements 20 are disengaged and the slide fastener 100 is opened.

The slider 60 may also include a pull tab (not shown) attached to a pull tab attachment rod 61 of the slider 60.

FIG. 7 is a flow chart of an embodiment of a method of manufacturing a slide fastener according to the second aspect of the present invention. In particular, the slide fastener 100 according to the embodiment shown in FIGS. 1 to 6B may be manufactured by this method. The method starts at step S1 with providing a pair of base sheets for the fastener tapes. At step S2, a polyurethane film is extruded on upper and/or lower surfaces of each base sheet to thereby obtain a pair of fastener tapes. The polyurethane may penetrate into the base sheet in one example. When the polyurethane is extruded on only one of the upper and lower surfaces of the base sheet, the one surface may be coated thickly and the other surface may be coated less thickly, with gaps of fabric of the base sheet permeated by the polyurethane. Next, at step S3, polyamide fastener elements having grooves are injected onto the fastener tapes. At step S4, a polyurethane seal part is injected onto each fastener tape and into the grooves of the fastener elements. The polyurethane of the seal part may be different from the polyurethane of the film in one example of the embodiment. In another example of the embodiment, the polyurethane of the seal part may be the same as the polyurethane of the film. Thereby, the slide fastener 100 explained above may be obtained.

As described above, according to a first aspect of the present invention, the edge portion of the fastener tape of each of the pair of fastener stringers is located in the groove of the fastener element of the opposite fastener tape respectively, when the slide fastener is in the engaged state. Thus, in the engaged state, the fastener elements may be stabilized against a rotation around the edge of the fastener tape which may occur in the slide fastener of U.S. Pat. No. 8,869,356 B2 where only the opposing seal part, but not the fastener tape, is received in the grooves of the opposing fastener elements. In addition, the feature that “the edge portion of the fastener tape of each of the pair of fastener stringers is located in the groove of the fastener element of the opposite fastener tape respectively, when the slide fastener is in the engaged state” according to the present invention implies that the edge portion of each fastener tape is located closer to the coupling portions of its fastener elements compared to the related art, in particular compared to U.S. Pat. No. 8,869,356 B2. Thereby, a peeling force on the fastener elements may be suppressed in the slide fastener according to the present invention compared to the related art. Furthermore, a consolidation block like in U.S. Pat. No. 8,869,356 B2 is not necessary. Thereby, the manufacturing efficiency of the slide fastener may be increased.

Each fastener tape is an elongated member which is long in a tape length direction. The tape length direction may also be called a front-back direction. A direction in which the slide fastener moves to engage the fastener elements may be called the front direction, and a direction in which the slide fastener moves to disengage the fastener elements may be called a back direction. When the slider slidably provided at the fastener element rows moves in the front direction to engage the fastener elements of the fastener element rows, the slide fastener is closed. When the slider moves in the back direction to disengage the fastener elements from the engaged state, the slide fastener is opened. Each fastener tape includes an upper tape surface and an opposite lower tape surface.

Each fastener element row includes a plurality of fastener elements. The fastener elements are attached to the opposing side portions of the fastener tape at a pitch which is a regular interval in the tape length direction. The fastener elements are in particular made from a resin material in one example. In one example, the fastener elements may be made from a polyamide resin. In particular, the fastener elements may be injected onto the fastener tape in one example.

Each fastener element includes a base portion attached to the respective fastener tape. The base portion may be in direct contact with the respective fastener tape. Each fastener element further includes a coupling portion which extends from the base portion towards the opposite fastener tape and is for engagement with another coupling portion of an opposite fastener element. In particular, the coupling portion extends beyond the edge portion of the fastener tape which is the outer boundary thereof towards the opposite fastener element.

In one example, the coupling portion may include a neck portion which extends from the base portion towards the opposite fastener element and which has a decreasing width in the tape length direction as the neck portion extends away from the base portion. A head portion may extend from the neck portion towards the opposite fastener elements and may be provided with two protrusions, one protruding in the front direction and the other one protruding in the back direction. Thereby, the head portion is bulging in the front-back direction.

The groove may extend through the coupling portion in the front-back direction in one example. Thereby, the seal part may easily extend from the fastener tape into the groove. The groove faces the opposite fastener tape. This means, the groove is open towards the opposite fastener tape.

The seal part is made of a material which allows to provide a sealing function. In particular, the seal part may include a sealing material impermeable to fluid, in particular impermeable to liquid and/or gas. In particular, the sealing material is impermeable to water. The seal part may be made of a plastic or a resin in one example and has preferably flexibility. For example, the seal part may be made of polyurethane. In general, the surface portion of the fastener tape to which the seal part adheres includes only a portion of the upper and/or lower tape surface of the fastener tape. In one example, the surface portion may include a portion of only the upper tape surface. In another example, the surface portion may include a portion of only the lower tape surface. In yet another example, the surface portion may include a portion of the upper tape surface and a portion of the lower tape surface. Preferably, the surface portion includes a portion of the side portion of the fastener tape between neighboring fastener elements. In one example, the surface portion includes a portion of the edge of the fastener tape which extends perpendicular to the upper and lower tape surfaces. The seal part extends into the grooves. Preferably, the grooves may be located completely outside the fastener tape. In one example, the seal part does not extend beyond the groove in the direction of the opposing fastener tape. In one example, the seal part may be an integral member.

In one example, the seal part may be injected, preferably directly injected, onto the surface portion of the fastener tape and into the groove.

The slider may include an upper blade (upper wing) and a lower blade (lower wing) which are distant from each other in an up-down direction which is a direction perpendicular to the upper and lower surfaces of the fastener tapes. The upper tape surface is facing in the up direction and the lower tape surface is facing in the down direction. A tape width direction is a direction which is perpendicular to the up-down direction and the tape length direction. The tape width direction may also be denoted as a left-right direction within this specification. The upper blade may include an upper blade surface and the lower blade may include a lower blade surface, which face each other in the up-down direction. Further, the upper blade may include flanges protruding from left and right side portions of the upper blade surface, respectively, in the down direction towards the lower blade. Similarly, the lower blade may include flanges protruding from left and right side portions of the lower blade surface, respectively, in the up direction towards the upper blade. The upper blade and the lower blade may be connected by a guide column which extends in the up-down direction. The upper blade, the lower blade and the guide column may define the boundary of a guide channel for the fastener elements. That is, when the slide fastener moves along the fastener element rows, the fastener elements may pass through the guide channel. The fastener elements may be in sliding engagement with the boundary of the guide channel when the slide fastener is moved along the rows of fastener elements to thereby engage or disengage the fastener elements.

In an expedient embodiment of the slide fastener, the fastener element may include an upper portion provided on an upper side of the fastener stringer and having an upper base portion provided on an upper tape surface of the fastener tape and a lower portion provided on a lower side of the fastener stringer and having a lower base portion provided on a lower tape surface of the fastener tape, and the fastener element may further include a connecting portion connecting the upper and lower portions in an up-down direction perpendicular to the upper and lower tape surfaces and being provided outside the fastener tape at the edge portion thereof. The fastener element thus clamps to the side portion of the fastener tape. The related fastener elements are described in the related art. But when these fastener elements are used with conventional slide fasteners, they may have a problem that they are not sufficiently well fixed to the fastener tape as the fastener elements and the fastener tape may be made of different materials which may not adhere well to each other. In the present invention, the seal part is adhered to a surface portion of the fastener tape and extends into the groove of the fastener element. In particular, the material of the seal part and the material of the surface portion of the fastener element may be such that the seal part adheres well to the surface portion in one example. For example, they may be made of the same or a similar plastic material, e.g. from polyurethane. Thereby, an additional fixing force may be applied to the fastener elements. When the grooves extend through the coupling portion in the front-back direction and the seal part extends completely through the grooves, the fixation may be further improved.

In a further expedient embodiment of the present invention, the coupling portion may include upper and lower coupling portions respectively extending from the upper and lower base portions towards the opposite fastener tape, and facing surfaces of the upper and lower coupling portions and a surface portion of the connecting portion form a boundary of the groove. The upper and lower coupling portions may provide a particular strong engagement of the slide fastener. The facing surfaces of the upper and lower coupling portions may face each other in the up-down direction. In particular, the seal part does not extend beyond the upper and lower coupling portions towards the opposite fastener element. In one example, the upper (lower) coupling portion includes an upper (a lower) neck portion which extends from the upper (lower) base portion towards the opposite fastener element and which has a decreasing width in the tape length direction as the upper (lower) neck portion extends away from the upper (lower) base portion. An upper (a lower) head portion may extend from the upper (lower) neck portion towards the opposite fastener element and may be provided with two protrusions, one protruding in the front direction and the other one protruding in the back direction. Thereby, the upper (lower) head portion is bulging in the front-back direction.

In one expedient example, the connecting portion is connecting to the upper and lower portions at the position of the upper and lower neck portions and the boundary of the groove is formed by facing surfaces of the upper and lower head portions and the surface portion of the connecting portion.

In a further embodiment, the seal part may cover a side surface portion of the base portion which extends in a direction away from the fastener tape in an up-down direction. Thereby, the fastener elements may be further fixed to the fastener tape. In an example where the base portion includes upper and lower base portions, the seal part may cover an upper side surface portion of the upper base portion which extends in a direction away from the upper tape surface in the up direction. Additionally, or alternatively, the seal part may cover a lower side surface portion of the lower base portion which extends in a direction away from the lower tape surface in the down direction.

In one embodiment of the present invention, the edge portion of the fastener tape may include a core thread. The core thread has a thickness in the up-down direction which is larger than a thickness in the up-down direction of an inner portion of the fastener tape. The core thread may improve the fixation of the fastener elements to the fastener tape, in particular, when they include the connecting portion outside the fastener tape according to the above embodiment. It is preferable in this case that the thickness in the up-down direction of the seal part on the tape surface is larger than a protruding thickness in the up-down direction of the core thread so that the seal part covers the core thread while having a smooth outer surface.

In one embodiment of the present invention, the fastener tape of each of the pair of fastener stringer may include a base sheet which is coated with and/or or impregnated by a plastic material which is impermeable to fluid. Thereby, the sealing function of the slide fastener may be further improved. The fluid may be a liquid and/or a gas, and in particular the fluid may be water. In one example, the plastic material may be provided in the form of a film or a layer on the base sheet of the fastener tape. The film or layer may be provided on only one of the upper and lower tape surfaces. Alternatively, the film may be provided on both upper and lower tape surfaces. In one example, the plastic material may be extruded onto the base sheet. In another example, the plastic material may be extruded or injected onto one surface of the base sheet so that the surface may be coated thickly and the other surface may be coated less thickly, with gaps of fabric of the base sheet permeated by the plastic material. The plastic material may be a resin material in one example. In one example, the plastic material may be a polyurethane. The base sheet may be made of a woven or nonwoven material in one example, but it is not limited to this.

The plastic material and the materials from which the fastener elements and the seal part are made are not particularly limited. In one example, the plastic material and the material from which the fastener element and the seal part are made are all different from each other. In one expedient example, the fastener element material has a higher melting point than the plastic material and/or the seal part material. In one example, the tensile strength of the seal part material is preferably at least 20 MPa and at most 80 MPa, more preferably at least 30 MPa and at most 70 MPa and most preferably at least 30 MPa and at most 60 MPa. In one example, the tensile strength of the seal part material is 50 MPa.

In one example, the elongation of the seal part material is preferably at least 500% and at most 800%, more preferably at least 600% and at most 700%. In one example, the elongation of the seal part material is 650%.

In one example, the Shore A hardness of the seal part material according to DIN ISO 7619-1 is preferably at least 70 and at most 100, preferably at least 80 and at most 90. In one example the Shore A hardness of the seal part material is 85.

In one expedient embodiment of the invention, each of fastener elements is made of a polyamide resin, the plastic material includes a first polyurethane and the seal part includes a second polyurethane. Fastener elements made from a polyamide resin are durable and have good molding properties which is preferable for manufacturing. Polyurethane has good sealing properties. However, polyurethane and polyamide do not adhere well to each other. Thus, the first and second polyurethane are preferably such that they adhere well to each other to thereby ensure that the fastener elements are additionally fixed to the fastener tape by the seal part which adheres to the fastener tape and extends into the grooves. Preferably, the first polyurethane and the second polyurethane are different from each other. In an expedient embodiment, the first polyurethane has a higher softness than the second polyurethane. Hardness/softness may be defined in relation to the Shore A hardness of the polyurethanes in one example, but the invention is not limited to this. It is further preferable, in particular for the manufacturing of the slide fastener, that the polyamide resin has a melting point which is higher than the melting point of the first and/or second polyurethane. In one expedient example, the polyamide is PA612, the first polyurethane is Elastollan 1180A and the second polyurethane is Elastollan C85A.

In one embodiment of the slide fastener according to the present invention, the seal part may include a seal edge portion protruding over the fastener tape in a tape width direction and extending parallel to the edge portion of the fastener tape. Thereby, a tight sealing abutment of the seal parts of the two fastener tapes may be ensured.

According to a second aspect of the present invention, there is provided a method for manufacturing the slide fastener according to any one of the above, the method including: providing a pair of base sheets for the fastener tape for each of the pair of fastener stringers; covering at least one of upper and lower surfaces of each of the base sheets with a plastic material to thereby obtain the fastener tape for each of the pair of fastener stringers; attaching the fastener element row for each of the pair of fastener stringers to each of the opposing side portions for the pair of fastener stringers; and for the fastener tape for each of the pair of fastener stringers, adhering the seal part to the surface portion of the fastener tape so as to extend beyond the edge portion of the fastener tape into the groove of the fastener element. This is different from the manufacturing process disclosed in U.S. Pat. No. 8,869,356 B2, in which first the fastener elements are provided on the base sheets of the fastener tapes, and then a resin is injected onto the tape which simultaneously forms the seal part. Such a manufacturing method may face the problem that the resin layer does not create a perfect seal, especially at the boundary between the fastener elements and the tape, as in general, the fastener element and the seal part are of different materials which may not adhere well to each other. These problems are overcome by the manufacturing method of the present invention. Just to be entirely clear, the upper and lower surfaces of the base sheets, at least one of the upper and lower surfaces of each base sheet being covered by the plastic material, become the upper and lower surfaces of the fastener tapes. The base sheet may be made out of a fabric which may include a woven or a non-woven material in one example.

In an expedient embodiment of the method according to the present invention, the covering at least one of the upper and lower surfaces of each of the base sheets with the plastic material may include extruding the plastic material onto each of the base sheets, the attaching the fastener element row for each of the pair of fastener stringers to each of the opposite side portions for the pair of fastener stringers may include injecting the fastener elements onto the fastener tape for the pair of fastener stringers, and the adhering the seal part to the surface portion may include injecting the seal part onto the surface portion of the fastener tape and into the groove of the fastener element. As the plastic material is extruded onto the base sheet, no parting line is created, as extrusion is done in a continuous process.