The invention relates to a method for the production of an adhesive closure device, preferably consisting of at least one plastic material. The invention relates furthermore to an apparatus for carrying out the method and an adhesive closure device produced according to the method and using the apparatus according to the invention.
These touch fastener elements, which also include mechanical fastening elements, with touch fastener elements made in a complementary manner, form a fastener which can be repeatedly opened and closed, hooks or mushroom-like fastener parts interacting with loop-like fastener elements of another touch fastener element with the formation of a touch fastener. Solutions are also known in which the same touch fastener elements of two different touch fastener elements interact with one another (hermaphroditic fastener).
Thus DE 699 22 264 T2 discloses supplying a belt-like backing part with a plurality of projecting stem parts to a molding gap between heatable molding rolls, into which by way of an extrusion means an additional molding belt of plastic material can be supplied which as the actual molding tool with mold recesses shapes the hot stem ends of the stem parts into head parts in order to obtain a mushroom-like touch fastener element in this way. Since the indicated head parts in the known solution are formed from the plastic material of the stem parts, in this respect the head parts are of smaller dimension due to low material charging in the free and therefore projecting head surface which is available for interlocking; this can adversely affect the required adhesion forces.
Conversely, U.S. Pat. No. 6,180,205 B1 proposes a production method using a molding roll in which a belt-like backing part can be connected to a plurality of hook fastener elements which can be dimensioned to be relatively large. For this purpose the molding roll on its outer periphery has hook-shaped mold recesses into which plastic material is pressed to fill the mold by way of a first extruder means. Excess plastic material on the outer peripheral side of the molding roll is removed by means of a cutting removal means which is technically called a doctor blade. By means of a second extruder means which is located downstream in the production direction, the backing part material is then applied and permanently connected to the hook-shaped fastener parts during the cooling process of the roll. A stripper roll then removes the finished fastener part from the molding means. Due to the hook geometry, difficulties can arise during the mold removal process and, furthermore, a relatively high proportion of plastic scrap is formed in the production process due to use of the indicated doctor blade.
WO 2006/099000 A2 furthermore discloses spraying a belt-like conveyor device on its upper strand side with droplets of plastic material, the plastic material being molded based on its surface tension into hemispherical shell bodies which are then permanently connected on their arching top to a belt-like backing part, with the formation of a touch fastener element. In one development of this solution it is also possible, in the manner of thickened stem parts, to supply a belt-like backing part which on its top bears grain-shaped agglomerates as the stern parts onto which then the hemispherical head parts can be placed. The touch fastener element which is produced in this way and which is designed to be used in particular as a fastener for baby diapers or incontinence diapers is, however, made relatively stiff and leaves much to be desired with respect to the fastener characteristics. US 2006/0220271 A1 discloses a comparable solution which, however, calls for a molding tool in the form of a molding roll with the corresponding mold recesses instead of a belt for production of hemispherical fastener elements. In this respect production of stem parts between the head parts and backing part is not done with this known solution.
U.S. Pat. No. 5,785,784 discloses a production method for producing a belt-like backing part on which there are a plurality of projecting stem parts. In a downstream production step the free stem ends are heated and then thicken as a result of the surface tension of the plastic material, in particular, into a hemispherical head part. If, in a continuation of the known solution, the head parts produced in this way are reshaped by means of a so-called calander rolling method, widened head part geometries are formed which with respect to the low material charge are made relatively small and are widened only in the direction of the earlier rolling direction.
Based on this prior art, the object of the invention is to further improve the known solutions while retaining their advantages, especially at low production costs to devise a reliable touch fastener which can be adjusted in wide ranges in terms of its fastening behavior. This object is achieved by a method with the features of claim 1; an apparatus with the features of claim 3 and a touch fastener element with the features of claim 6.
The method according to the invention is used to produce a touch fastener element, preferably consisting of at least one plastic material which is characterized in that a backing part with a plurality of projecting stem parts is connected to individual head parts such that at least for some of the indicated stem parts their free ends come into contiguous or embedded contact with the contact side of the respectively assignable head part. By subsequently placing separately produced head parts on the free end side of the assignable stem parts different material components of the stem parts can be combined with head parts in very wide ranges and likewise different geometries for head parts and/or stem parts can be defined. Based on the plurality of combination possibilities, a plurality of technical parameters can thus be set in a touch fastener element produced in this way. The method according to the invention is moreover reliable in application and can be economically implemented.
An apparatus has proven to be especially economical for carrying out the method in which for the individual head parts there is a molding tool with a plurality of mold recesses which correspond to the respective head geometry, and with a supply device for the already finished backing part with the stem parts whose free ends can be inserted into the mold recesses by means of the supply device.
The touch fastener element is especially serviceable and mechanically durable if the stem parts and head parts consist of plastic materials which are different from one another, in particular the stem parts are formed from a thermoplastic and the head parts consist of acrylate material. The relatively hard acrylate material for the respective head part allows the possibility of resistant hooking underneath for the loops of a corresponding touch fastener element so that a touch fastener structured in this way enables very high adhesive and peeling strength values.
Other advantageous embodiments of the solution according to the invention are the subject matter of the other dependent claims.
The solution according to the invention is detailed below using one exemplary embodiment as shown in the drawings. The figures are schematic and not to scale.
The method according to the invention is detailed below using the production apparatus as shown in
For molding the individual head parts 16 there is a molding tool designated as a whole as 22, with a plurality of individual mold recesses 24 which correspond to the respective head geometry in terms of their configuration. The mold recesses 24 are a component of a molding belt 26 which revolves in the manner of a transport belt, the mold recesses 24 of the upper strand being filled with plastic material and the lower strand guiding essentially the empty mold recesses 24. The mold recesses 24 are in turn repeatedly present in a regular or irregular distribution in the transverse and longitudinal direction of the molding belt 24.
Furthermore there is a supply device designated as a whole as 28 for the already finished backing part 12 with the stem parts 14 whose free ends 18 can be inserted into the mold recesses 24 by means of the supply device 28. For this purpose, the supply device 28 has a type of storage roll 30 from which the stem part-fastener material can be unwound. By way of corresponding deflection rolls 32 the belt material can be supplied to the molding tool 22 and the complete touch fastener product can be taken up on the end onto a transport roll designated as 34 for further transport. For the sake of simpler depiction, individual transport and guide devices have been omitted, likewise the heating and cooling devices for the production apparatus are not shown. The transport direction of the molding tool 22 and the supply device 28 is, however, indicated with an arrow 36.
As
To produce the fixed connection between the stem parts 14 and the head parts 16, in turn a curing device 40 which is not detailed is used which is located preferably at the end of the connecting process, specifically a short distance in front of the point before, viewed in the direction of the arrow 36, the finished touch fastener element removed from the molding tool 22 is carried away in the direction of the transport roll 34. Depending on the respective plastic material used, the curing device 40 can be a conventional heat source, but also an UV emitter and the like. If acrylate material is used for the head parts 16, the curing device 40 is preferably a UV emission source.
Touch fastener elements, produced according to the illustrated method using the described apparatus, are shown enlarged in
It is surprising to one with average skill in the art in the field of fastener technology that for mushroom-head fastener systems he can connect any head parts 16 to any stem part material 14 in order in this way to be able to offer functional touch fasteners in a wide range of applications. As
Depending on the depth of the mold recesses 24 of the molding tool 22 which are used, different lengths for the stem parts 14 can also optionally be implemented so that then the head parts 16 end at different level heights relative to the belt-like backing part 12. The backing part 12 itself can also consist of a multiextrusion layer arrangement or can have be film-like and elastically stretchable. The indicated head parts 16 viewed from overhead can form spherical shell bodies which are smooth to the outside; but implementations in polygonal form, in particular in a hexagonal shape, are also possible. By using acrylate material for the head parts 16 they also form a type of edge protection toward their surrounding edge 42; this in turn benefits the service life of the overall fastener.
Number | Date | Country | Kind |
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10 2007 015 441.2 | Mar 2007 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2008/000646 | 1/29/2008 | WO | 00 | 8/31/2009 |