Separator for sheets
The invention relates to a separator for sheets, in par¬ ticular fragile sheets such as glass sheets, comprising a strip of honeycomb material which is provided on both sides with a cover layer, in which on a side of the separator connecting means are arranged for making a detachable connection with a sheet.
Such separators are used in the glass sheet industry. The glass leaves the glass melting furnace as a continuous band, which is cut into sheets, after which the sheets are placed upright against each other. The sheets have, for example, a height of 3 metres and a width of 6 metres. In order to be able to transport several sheets simultaneous¬ ly, for example every 8 to 10 sheets a number of separators are disposed so that there is a gap between each set of glass sheets. Known separators have a thick¬ ness of approximately 25 mm. To obtain sufficient strength, without the weight and the costs being too high, the known separators are made of paper honeycomb material with a cardboard cover layer on both sides.
The separators are automatically laid on a glass sheet after the latter has been cut off, but prior to placing upright. To prevent the separators from sliding, they are provided on one end with a thickening, called a nose in the technical field, which hooks behind the upper edge of the glass sheet when placing it in an upright position. Because there is still the risk that when handling the glass sheet a separator moves and/or falls on the ground, the result being that the production process is disturbed, the known separator is provided with one or more suction cups. When the separator is placed automatically some pressure has to be exerted so that each suction cup ad¬ heres detachably to the glass sheet. After use the
separators can be detached from the glass sheet.
The known separator with at least one suction cup has the disadvantage that in the strip of honeycomb material a recess has to be made for the suction cup to receive the suction cup for the greater part, so that the separator does not get too thick. Apart from this the suction cup should not leave any traces on the glass, whereby only certain plastics are suitable as material for the suction cups. A suction cup of that kind of plastic, however, has the disadvantage that it is difficult to glue to the honeycomb material. So that the separators can be stacked for storage and because the suction cup should not adhere to the next separator, each separator has to be provided at its rear side as well with a recess, which entails extra costs, and the separators have to be stacked exactly, placing higher demands on the production process of the separator. Furthermore, the suction cup has to be glued in the correct position in its recess so that the edge of the suction cup is parallel to the cover layer of the strip of honeycomb material, because the suction cup cannot otherwise suck onto the glass. This requires an exact and thus costly manufacture.
It is an object of the invention to provide a separator which can be manufactured in a simple and cheap way and can be handled easily.
According to the invention this object is achieved with a separator, such as set forth in the opening paragraph, in which the connecting means comprise an adhesive layer which is applied to a cover layer of the strip of honeycomb material.
Because the connecting means are applied as an adhesive layer to the cover layer of the honeycomb material no recesses have to be made therein. The adhesive layer can
easily be applied to the cover layer, in view of the fact that the adhesive layer does not have to be positioned in a special way with regard to the cover layer, because after application the side which adheres detachably to the sheet is automatically parallel to the cover layer. The adhesive layer is provided with a protective layer, which is removed directly before placing on a sheet so that the adhesive layer is kept dust free.
The adhesive layer preferably comprises a layer of syn¬ thetic foam which has open cells on the side that adheres detachably to the sheet, so that when adhering to the sheet the many open cells act in the manner of small suction cups which are also easily detached because, as a result of the deformation of the foam from an edge of the adhesive layer, they can progressively work loose, and do not all have to be loosened at the same time.
According to an advantageous embodiment the synthetic foam is a polyvinyl chloride foam, which leaves no traces on glass and can be processed well.
Preferably the adhesive layer has thickness of 1 to 3 mm so that with a thickness of approximately 25 mm of the honeycomb material the separator hardly gets any thicker as a result of using the adhesive layer and little material is needed for the adhesive layer.
In an advantageous way the adhesive layer is applied with a glue to the cover layer of the strip of honeycomb material so that the separator provided with an adhesive layer is simple to manufacture. In addition the glue is preferably a pressure sensitive glue, so that it is pos¬ sible to have the adhesive layer provided with glue in stock and after applying the adhesive layer the separator can be used immediately without having to wait.
In the case of an elongated separator which has a thick¬ ening at one end so as to hook behind the glass sheet, it is advantageous if the adhesive layer is applied in the form of an adhesive strip at a distance from the other end of the separator to the cover layer of the strip of honeycomb material on which the thickening is located. An adhesive strip can be easily automatically applied to the separator from a roll, and after hooking the separator with thickening about the edge of the glass sheet the adhesive strip at a distance from the other end suffices to securely detachably connect the separator by pressing to the glass sheet. The separator is thus suited to be completely automatically disposed on the glass sheet.
In the case of an elongated separator without thickening the adhesive layer is preferably applied in the form of two lengths of adhesive strip to a cover layer of the strip of honeycomb material, one length of adhesive strip being applied at a distance from each end of the separator. Because the thickening does not have to be made the production process is simple, seeing as the adhesive strips can be applied simultaneously. Also less material is needed for an adhesive strip than for a thickening. For disposing this separator on a glass sheet other apparatus is needed because the separator does not hook about the edge of the glass sheet and because the separator has to be pressed at the location of both lengths of adhesive strip.
For a detachable connection which adheres securely to a glass sheet, adhesive strip with a width of approximately 25 mm suffices.
According to a first advantageous embodiment the adhesive strip is applied substantially in the longitudinal direc¬ tion of the separator and the adhesive strip has a length of 150-250 mm. As a result it is possible that the user in
the glass factory can himself apply the adhesive strip to the separators since the exact position and direction of the adhesive strip requires less precision when applying it in the longitudinal direction on the separator.
According to another advantageous embodiment the adhesive strip is applied substantially in transverse direction over the entire width of the separator. This embodiment makes it possible that the honeycomb material with its cover layers is manufactured in great width after which the adhesive strip is applied as a long tape in width direction and the honeycomb material can then be cut up into narrow elongated separators. The width of a separator is usually approximately 70 mm.
The invention will now be described on the basis of two preferred embodiments as shown schematically and not to scale in the accompanying drawings.
Figure 1 shows a schematic front view of an embodiment of a separator according to the invention.
Figure 2 shows a side view of the separator of figure 1.
figure 3 shows a schematic front view of another em¬ bodiment of the separator according to the invention.
Figure 4 shows a side view of the separator of figure 3.
The figures 1 and 2 show a first embodiment of the separator according to the invention. The separator 1 consists of honeycomb material 2 with on one side a first cover layer 3 and on the other side a second cover layer 4, in which on the first cover layer 3 a thickening or nose 5 is applied to a first end and at a distance from the other end a length of adhesive strip 6 is applied. In figure 1 a small portion the first cover layer 3 is cut
away to show a number of honeycomb cells. In this em¬ bodiment the thickening 5 also consists of honeycomb material, but can also consist of another material. The adhesive strip 6 consists of polyvinyl chloride foam which is glued to the first cover layer 3 by means of a pressure sensitive glue. Whilst applying the adhesive strip to the cover layer and during the storage of the separator the adhesive layer is covered by a silicone protective layer (not shown) which is removed from the adhesive layer just before placing the separator on the glass sheet.
In the embodiment the separator has a length a of more than 3 metres, a width b of 70 mm and a thickness c of 23 mm. The thickening has a height d of 45 mm and a thickness e of 23 mm. The thickening 5 is at the upper end of the separator, and the adhesive strip 6 with a width of 25 mm is applied at a distance g of approximately 0.5 metres from the lowest end of the separator. The adhesive strip 6 has a thickness of 1 to 3 mm. Depending on the height of the glass sheet another distance g can be selected instead of the distance of 0.5 metres.
Figure 3 shows another embodiment of the separator consis- ting of the same honeycomb material which is provided on both sides with a cover layer and which is now indicated with the reference number 10, but where no thickening has been made. For a secure adhesion to a glass sheet the separator is now provided with two lengths of adhesive strip 6 , each of which are applied at a distance of ap¬ proximately 1 metre from an end of the separator. In this way an equal spreading of the adhesive strip over the length of the separator is achieved. Otherwise the ad¬ hesive strip 6 is the same as the adhesive strip in the figures 1 and 2.
In the embodiments shown the adhesive strip 3 is applied
over the width of the separator. This offers advantages when manufacturing the separators, seeing as the honeycomb material with cover layers can then be manufactured over a large width and the adhesive strip can be applied thereon as a long strip in width direction, after which the whole can be cut up into narrow elongated separators.
It is, however, also possible that the user in the glass factory applies the adhesive strip himself to the honeycomb material, and then it is easier to apply the adhesive strip in the longitudinal direction of the separator, since then the adhesive strip, as far as position and direction are concerned, does not have to be applied so exactly to the cover layer. For a better ad- hesion it is then possible to apply a greater length of adhesive strip, for example an adhesive strip with a length of 150 to 250 mm.
JK/FL