EP0530470A1 - Slide fastener, particularly for plastic bags - Google Patents

Abstract

A slide fastener, particularly for plastic bags, consists of a first fastener strip (3) having at least one first fastener profile (6), a second fastener strip (4) having at least one second fastener profile (7), and a slider (5) by means of which the fastener profiles (6, 7) can be engaged and disengaged, the fastener strips (3, 4) being made of plastic. In order to provide an environmentally friendly slide fastener of this type, the slider (5) is also made of plastic, namely the same plastic or a similar plastic to the two fastener strips (3, 4). <IMAGE>

Description

The invention relates to a slide fastener, in particular for plastic bags, consisting of a first fastener tape with at least one first fastener profile, a second fastener tape with at least a second fastener profile, and a slide through which the fastener profiles can be engaged and disengaged, the fastener tapes being made of Are plastic. The invention further relates to a slide for such a slide closure and a plastic bag, a plastic bag or a plastic bag with such a slide closure.

Such slide closures are generally known in practice. In the known slide fasteners, the slide in these slide fastener-like slide fasteners is still made of metal. Attempts have already been made with rigid plastics, for example polyacetals, but these slides are unable to securely close the slide fastener tape with the previous S-shaped construction. The end opening of this slide springs back too easily. The slide lock can be closed and opened with the metal slide.

In order to prevent the slider from being pulled out at the respective ends of the pockets or bags, so-called end clamps, which are also made of metal, are attached to the ends of the slide closure. For lighter applications, the ends of the fastener tape can also be spot welded.

The metal slide and metal end clamps have the disadvantage that they are not only very heavy, but that the plastic bags or bags equipped with them can only be used or reused (recycled) when the metal parts, i.e. the slide and the end clips have previously been painstakingly removed by hand. These metal parts must then be disposed of separately.

The object of the invention is therefore to propose an environmentally friendly slide closure of the type mentioned.

According to the invention, this object is achieved in that the slide is made of plastic, either from the same plastic as the two fastener tapes or from a similar - related - plastic. The plastic bag can also be made of the same or similar - related - plastic. The slide fastener and also the plastic bag to which it is attached can then be recycled in an environmentally friendly manner without the need to sort out individual parts of the slide fastener or the plastic bag and to dispose of them separately.

Advantageous further developments are described in the subclaims.

A thermoplastic is preferably used. The plastics polyethylene and polypropylene are particularly suitable. These materials can be reused (recycled) in the manner described. The plastic polyethylene is used in practice in two different basic forms, namely, on the one hand as so-called high-pressure polyethylene (LDPE), and on the other hand as so-called low-pressure polyethylene (high density polyethylene = HDPE). Both basic forms can be reused (recycled) together, so that they are to be regarded as "the same plastic" in the sense of this application. Similar or related plastics can also be recycled together in the present case, that is, ground in and compounded and reused without separation. For example, if the bag is made of polyethylene and the slide is made of polypropylene, this is true, as numerous tests have shown. Both related plastics are olefins, and the relatively low addition of the polypropylene of the pusher to the larger amount of polyethylene in the bag or sack affects the recyclate only insignificantly. Tests have shown that, for example, an admixture of up to 25% polyethylene to polypropylene results in a reprocessable polyethylene regrind with only insignificantly softer properties. Conversely, an addition of polypropylene to polyethylene up to 25% results in only an insignificantly harder regrind.

So if the plastic bag or the plastic bag and the slide closure including slide and end clamps consists of one of the plastics mentioned, the bag can be ground directly and as a whole and processed into a new plastic part or a new film. This is not only possible with polyethylene and polypropylene, but also with other thermoplastic materials.

A further advantageous development is characterized in that a first, continuous channel is provided for the first fastener tape in the slide and that a second channel is provided for the second fastener tape in the slide, which is in the first channel at an angle of at least 20 ° flows. This creates a completely new construction of the slide. The known sliders for slide closures are made a metal alloy. The end of the slide must compress the slide fastener tapes after entering the slide opening and thus close. For this purpose, relatively high forces must be applied to the slide fastener tapes. In order to be able to exert these relatively high forces on the slide fastener edges, the slide fasteners for slide fasteners have so far been produced from a metal alloy. Due to the two side slots through which the slide fastener tapes have to be inserted into the slide, only the heart of the approximately S-shaped slide body holds it together. If this centerpiece, which can also be referred to as a web, is not sufficiently resistant to bending, the slide end gapes too far, so that the slide fastener tapes are not compressed sufficiently. The slide lock cannot then be closed.

The plastics from which foils for plastic bags and plastic bags are made are relatively soft. Known sliders can therefore not be made from these plastics. The centerpiece of the slider would be far too soft, so that the slider end - as described above - would open and the closure band would not close.

In order to counteract this tendency to gap open, a completely new structure of this slide was created. The special construction of this slider makes it possible to significantly strengthen the centerpiece and to make the important, stressed parts more resistant to bending. Due to the steep angle of incidence of the second channel, the closing of the two slide fastener tapes is also significantly promoted. As a result, the design of the slider can be kept so small that when processing the slider with the fastener tape and the plastic bag or the plastic bag there are no significant disadvantages compared to the previous metal slides.

Would the well-known metal slide valve simply in all Parts would be reinforced, it would be so big and bulky that when welding the slide fasteners, in which the slide is already open, incorrect welds would occur continuously. With such a large slider, the welding tabs of the slide closures would then have to be significantly lengthened. This would be associated with disadvantageous, greater material consumption. Nevertheless, difficulties would arise when shipping the bags because of the large volume. In addition, there would be the danger that if the slides were lying on top of one another if the slides were too large, they would press in and damage the film of the pockets above and below.

Therefore, the smallest possible design of the slide is essential. The innovation creates a slide with which the greatest possible stability and security can be achieved with the smallest possible, smallest possible construction. The second fastener tape is inserted through the second channel at a particularly steep angle into the slide.

The first channel can taper in a funnel shape. This taper is provided towards the closing end of the slide. The height of the channel thus decreases towards that end of the slide at which the fastener tapes emerge from the slide in the closed state. Here, the height of the first channel at this exit end can be less than the height of the fastener tapes. The outlet opening for the two closed fastener tapes can be kept so narrow because, despite the relatively large inlet angle between the first and second channels, the fastener tapes require a certain amount of pressure in order to press the fastener profiles of the fastener tapes into one another. Since the plastic used for the fastener tapes is relatively elastic, the height of the outlet opening can be kept very low. This height can be chosen towards zero, so that the closed slide fastener tapes, which in practice can be about 2.2 mm thick (high), bend the outlet opening of the slide and to a certain extent Extend the degree until the resistance of the plastic becomes so strong that it compresses the fastener tapes. The spring action of the slide caused thereby is used to close the fastener tapes.

In another embodiment, if the slide is made of polypropylene, the outlet opening of the slide can even be approximately 2.30 to 2.35 mm with a closed slide fastener tape thickness of 2.2 mm, for example. As tests have shown, this end opening is sufficient to securely close the band, because the construction of the slide means that the core or the web is sufficiently rigid to securely close the band, which further enhances the steep angle of incidence of the second band. On the other hand, the slide is not in a stretched position in extended rest position and does not lose its contact pressure when actuated due to a possible flow behavior.

According to a further advantageous development, the second channel tapers in a funnel shape. The taper is towards the first channel. The cross section of the second channel thus becomes narrower towards the first channel. This increases the functional reliability of the slide.

The slide can be essentially cuboid.

According to a further advantageous development, an end clip is provided at each end of the slide closure, which is essentially U-shaped. At its end edges, it can have mutually pointed, tapering end edges. The end clips are preferably made of the same plastic as the two fastener tapes.

It is advantageous to manufacture several end clamps in one injection molded part. The end brackets of the injection molding are connected to one another by narrow webs, so that one end bracket each can be demolished. The end clip can be welded on at the end of the bag or at the end of the slide fastener using heating pliers.

Embodiments of the invention are explained below with reference to the accompanying drawings.

Fig. 1

einen Schieber für einen Gleitverschluß in einer Seitenansicht,

Fig. 2

den in Fig. 1 dargestellten Schieber in einer Ansicht von vorne (gem. Fig. 1 von rechts),

Fig. 3

eine Kunststofftasche mit einem Gleitverschluß und zwei Endklammern in einer Ansicht von vorne,

Fig. 4

in einer der Fig. 3 entsprechenden Darstellung eine Kunststofftasche mit einem Gleitverschluß, an dessen Enden punktartige Verschweißungen vorhanden sind,

Fig. 5

eine Reihe von Endklammern, die in einem einzigen Spritzgußteil hergestellt sind und die durch schmale Stege miteinander verbunden sind,

Fig. 6

eine Heizzange, mit der eine Kunststoffendklammer auf den Gleitverschluß aufgeschweißt werden kann,

Fig. 7

den in den Fig. 1 und 2 dargestellten Schieber in einer Ansicht von unten,

Fig. 8

den in den Fig. 1, 2 und 7 dargestellten Schieber in einer der Fig. 1 entsprechenden Darstellung mit angedeutetem ersten Kanal und

Fig. 9

den in den Fig. 1, 2, 7 und 8 dargestellten Schieber in einer den Fig. 1 und 8 entsprechenden Darstellungen, allerdings von hinten.

In the drawing shows

Fig. 1

a slide for a slide closure in a side view,

Fig. 2

1 in a view from the front (according to FIG. 1 from the right),

Fig. 3

a plastic bag with a slide closure and two end clips in a view from the front,

Fig. 4

in a representation corresponding to FIG. 3, a plastic bag with a slide closure, at the ends of which point-like welds are present,

Fig. 5

a series of end clamps which are made in a single injection molded part and which are connected to each other by narrow webs,

Fig. 6

heating tongs with which a plastic end clip can be welded onto the slide lock,

Fig. 7

the slider shown in Figs. 1 and 2 in a view from below,

Fig. 8

the slide shown in FIGS. 1, 2 and 7 in a representation corresponding to FIG. 1 with indicated first channel and

Fig. 9

1, 2, 7 and 8 shown in a slide corresponding to FIGS. 1 and 8, but from behind.

Fig. 3 shows a plastic bag 1 with a slide fastener 2, which consists of a first fastener tape 3 and a second fastener tape 4 and a slide 5 through which the fastener profiles 6, 7 (Fig. 2) of the fastener tapes 3, 4 in engagement and can be disengaged. End clips 8 are provided at the ends of the fastener tapes 3, 4.

These end brackets 8 are shown in an enlarged perspective in FIG. 5. They are essentially U-shaped. Several, in the present case four end clips 8 are connected to one another by narrow webs 9. The end brackets 8 and the webs 9 are made as a single injection molded part. One plastic end clip 8 can be torn off.

The end bracket 8 is then welded in the manner shown in FIG. 6 by means of heating tongs 10 at the end of the bag 1 onto the slide closure 3, 4.

FIG. 4 shows, in a representation corresponding to FIG. 3, in which the same parts are provided with the same reference numerals, a plastic bag 1 with a slide closure 2, which in turn consists of two closure straps 3, 4 and a slide 5. In this case, instead of the end clamps, 2 point-like welds 8 'are provided at the ends of the slide closure. This version is suitable for lighter applications.

3 and 4, the pockets 1, the slide fasteners 2, consisting of fastener tapes 3, 4 and sliders 5, and the end clips 8 are all made of the same or similar plastic.

As can be seen from FIGS. 1, 2, 7, 8 and 9, a first, continuous channel 11 for the first fastening tape 3 is provided in the slide 5. On one side of the slider 5, a lateral slot 13 adjoins this first channel 11, through which the flag 12 adjoining the first closure band 3 can pass.

Furthermore, a second channel 14 for the second closure band 4 is provided in the slide 5. The second channel 14 opens into the first channel 11 at an angle of at least 20 °. In practice, this angle is preferably in the range between 20 and 50 °.

A slot 15 also adjoins the second channel 14 laterally in order to allow the passage of the flag 16 adjacent to the second fastener tape 4.

As can be seen from Fig. 1, the fastener tapes 3, 4 are fed from the right. When the slide 5 moves to the right in FIG. 1, the fastener tapes 3, 4 emerge from the slide 5 on the left in the closed state.

The first channel 11 tapers in a funnel shape, specifically towards the closing end 17 of the slide 5. As can be seen from FIG. 1, the height of the first channel at its outlet end 17 can be less than the height of the fastener tapes. In this case, this height is zero, so that the approximately 2.2 mm thick closed slide fastener tape 3.4 bends the end opening of the slide at the outlet end (left in FIG. 1) and stretches to a degree at which the resistance of the Plastic material of the slider 5 becomes so strong that it reliably compresses the fastener tapes 3, 4 and the fastener profiles 6, 7 of the fastener tapes 3, 4 are reliably hooked.

The second channel 14 is funnel-shaped towards the first channel 11. This increases functional reliability. For A reliable function of the slider 5 does not matter whether the second sealing tape 4 - as shown in FIG. 1 - lies on the upper surface 18 of the channel 14 or - not shown in the drawing - on its lower surface 19. There is sufficient play for the insertion of the second fastener tape 4 into the funnel-shaped second channel 14. The second fastener tape 4 is reliably drawn into the funnel-shaped second channel 14 and reliably positioned to the first fastener tape.

The slide 5 is essentially cuboid. The first channel 11 runs centrally through the longitudinal axis of the slide 5. The second channel 14 begins at the underside of the slide 5 and runs obliquely at an angle to the first channel 11. At the entry end 20 of the slider 5, a projection 21 is provided below the entry point of the first fastener tape 3, which is approximately triangular in cross section.

As shown in FIG. 5, the end clamps 8 have mutually facing, tapering end edges 22 which rest against one another in the initial state shown in FIG. 5.

The slot 13 of the first channel 11 and the slot 15 of the second channel 14 face each other.

With the slide 5, a pull tab is connected, which is not shown in the drawing figures. Such pull tabs are already well known. They can be manufactured separately and connected to the slider. But it is also possible to form the pull tab in one piece with the slide 5.

Claims (13)

Slide closure, in particular for plastic bags, consisting of a first closure band (3) with at least a first closure profile (6), a second closure band (4) with at least a second closure profile (7), and a slide (5) through which the closure profiles ( 6,7) can be engaged and disengaged, the fastener tapes (3,4) being made of plastic,

characterized by

that the slide (5) is made of plastic, namely from the same plastic or from a similar plastic as the two fastener tapes (3, 4). Slide fastener according to claim 1, characterized in that the fastener tapes (3, 4) and / or the slide (5) are made of thermoplastic material, preferably of polyethylene and / or are made of polypropylene. Sliding closure according to one of the preceding claims, characterized in that a first, continuous channel (11) for the first fastener tape (3) is provided in the slide (5) and that a second channel (14) for the second closure band (4) is provided which opens into the first channel (11) at an angle of at least 20 °. Sliding closure according to claim 3, characterized in that the first channel (11) tapers in a funnel shape. Sliding closure according to claim 4, characterized in that the height of the first channel (11) at its outlet end (17) is less than the height of the closure straps (3, 4). Sliding closure according to claim 4, characterized in that the height of the first channel (11) at its outlet end (17) is 0.10 to 0.15 mm greater than the height of the closure straps (3,4). Sliding closure according to one of claims 3 to 6, characterized in that the second channel (14) tapers in a funnel shape. Sliding closure according to one of the preceding claims, characterized in that the slide (5) is cuboid. Sliding closure according to one of the preceding claims, characterized by an end bracket (8) which is essentially U-shaped. Sliding closure according to claim 9, characterized in that the end clip (8) is made of the same material or of a similar material as the closure strap or straps (3,4) and / or like the slide (5) and / or like the plastic bag (1). Sliding closure according to claim 9 or 10, characterized in that the end clamp (8) has pointed end edges (22) which face one another. Slide for a slide closure according to one of claims 1 to 11. Plastic bag, plastic sack or plastic bag, characterized by a slide closure according to one of claims 1 to 11.

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