Sealing strip and a synthetic cavity plate sealed therewith

Abstract: A strip is described which is suitable for sealing the ends of synthetic plate material dust-proof, yet water and water vapour permeable and ventilating. Such plate material comprises at least two basically parallel synthetic plates which are kept at each other's distance by means of dividing walls, enclosing a number of elongated channels which end at the ends of the synthetic plate material. The strip comprises a first strip with an open-pore structure which is air and (water) vapour permeable, yet dust-proof, and which has a pattern coat with a pattern of at least one layer which completely seals the pores at their location. In addition, a synthetic plate material which is sealed by means of the above-mentioned strip, as well as a method for sealing the ends of such a synthetic material are described.

Description: The present invention relates to a sealing strip for sealing in a dust-proof, yet ventilating manner comprising pores over substantially the entire surface, which pores are dust-proof, yet water and water vapour permeable. The invention moreover relates to a synthetic cavity plate comprising at least two basically parallel synthetic plates which are kept at a distance by means of dividing walls, thus enclosing a number of elongated channels ending at a side face of said cavity plate. A cavity plate of the above-mentioned kind is, for example, applied for light-transparent roof coverings, sun rooms, etc. In these cases, translucent plastic is generally used, whether or not coloured, e.g. acrylate or polycarbonate, for example, those known by the trade names 'Plexiglass' and 'Lexan'. The dividing walls and the plates enclose cavity channels of generally polygonal cross-section, specifically triangular or quadrangular, which ensure the desired heat insulation. In order to avoid dust particles and small organisms from entering into the channels, the leading ends of these channels are sealed dust-proof. A hermetic seal of the channel ends will, however, lead to condensation in the cavity of the cavity plate. Such condensation is not only irritating, it may well provide a culture medium for fungi, algae and micro-organisms, which are inevitably present in the air. In the long run, the growth of these organisms in the channels will lead to highly unpleasant looking sediment, which is disadvantageous to the light transmission of the cavity plate. Although the sealing of the channels is dust-proof, it should therefore nevertheless be water and vapour permeable as well as ventilating in order to avoid the above-mentioned problem. In that case, condensation, if any, may be discharged via the ends of the cavity channels. A sealing strip of the kind referred to at the opening paragraph is known from European patent application EP 376.386. The strip described therein comprises a first strip of non-woven material which, on the one hand, is dust-proof, on the other hand, however, ensures the desired ventilation and water as well as water vapour discharge, and a second strip attached onto the first in the form of an air-proof and humidity-proof film, which extends beyond the first strip and which is provided with an adhesive coat by which the film adheres to the first strip and by which the assembly is adhered around the edge of the cavity plate. The film comprises a series of openings where the first strip is left bare. A drawback of this strip is that it ensures ventilation and permeability of water and water vapour only at locations where the film is provided with openings. This means that ventilation and water discharge is only possible in a relatively small surface. As a consequence, condensed water seeping from the cavity channel accumulates beneath the openings where the strip is sealed. This is particularly the case, if the cavity plate is placed at a small angle, which is often the case with application in sun rooms or light-transparent roof coverings. Moreover, the known strip has the drawback that the film extends just a little from the first strip at the area of the openings in the film, which adversely affects the strength and durability of the strip assembly. In addition to this, at the edge of the cavity plate the strip commonly comprises a stack of the first strip together with the film, contrary to the part of the strip which is located at the outside wall of the cavity plate in an attached state, which only comprises the film as it extends beyond the first strip. As a result, the strip thickness is thicker at the edge than it is along the outside wall of the cavity plate. This increased thickness is disadvantageous, since the application of cavity plate sealed by means of the above-mentioned strip generally involves sliding elements which are slid onto the ends of the cavity plate, during which damage may be caused at the thickening along the edge portion of the strip. Another sealing strip and cavity plate sealed by a sealing strip is known from German patent application 38 38 641. This known sealing strip is wrapped around a leading edge of the cavity plate and adheres to opposite sides thereof. The strip is made of polyurethane and has pores over its entire surface which are ventilating and permeable to water vapour, but impermeable to dust and particularly to water. Condens water inside the cavity plate is hence not likely to be discharged by this strip and instead will tend to accumulate behind it, giving rise to the growth of fungi and associated stains. Alternatively a leading edge of a cavity plate may be sealed as described in European patent application 711.883. In this case the sealing consists of a foam with an open pore structure which extends over the entire surface of the leading ends of the channels within the cavity plate. The open pore structure of this foam resides in open channels extending through the foam layer which allow for ventilation and discharge of water but are impermeable to dust and other particles. Although this sealing method thus allows discharge of water and ventilation over the entire surface of the leading edge of the cavity plate, the relatively large ventilating surface of this sealing adversely affects the isolation value of the cavity plate as a whole. The present invention has inter alia for its object to provide a sealing strip and cavity plate whose leading edge is sealed in a dustproof, yet ventilating and water permeable manner, allowing ventilation and discharge of water over the entire surface without the aforementioned drawbacks. To this end, a sealing strip of the kind referred to in the opening paragraph is characterized in that some of the pores in the strip are completely sealed according to a pattern and in that a backside of said strip is provided with adhesive tracks at opposite longitudinal edges thereof by which said strip is capable of adhering to said cavity plate. Such a strip provides a water as well as water vapour permeable and ventilating, yet dust-proof sealing across the entire surface of the leading end of the cavity channels, while a large amount of air and humidity control is possible by means of the pattern according to which pores are locally sealed completely. Due to the fact that the cavity channels are sealed in a water(vapour) permeable manner over the entire surface of their leading ends it is prevented that water accumulates behind the strip. The material for the strip with the open-pore structure is particularly selected on the basis of its filter function, while the selectivity may be improved even more and the ventilation reduced to a desired level, thus enhancing the insulation value of the cavity plate, by means of a pattern-based coating,. The filter function of the material of the strip with the open-pore structure particularly refers to the pore size of the material. This determines which particles can permeate the material and which are stopped by it. In practice, the pore size will show a certain distribution which has a certain average value. This average value, as well as the absolute number of pores that are too large are decisive in the selectivity process. By applying a pattern in accordance with the invention, a number of these pores, whether or not too large, may be sealed. Although many working methods can be opted for, for applying the pattern where the pores are sealed completely, it is preferred that said pores are sealed by a screen print coating which is water and air impermeable and which has been provided according to said pattern. It is possible to apply a very accurately defined pattern by means of screen printing, as a result of which the ventilation is regulated to the greatest possible extent, while the pattern can be varied in a relatively simple way in order to optimally meet the customer's demands. Another advantage is that the accurately defined pattern-based coating of the strip prevents a thickening of the strip at the edge of the cavity plate, and as a result, it does not have the drawbacks commonly known of the strip according to the prior art described hereinbefore. Since the strip is provided with an adhesive layer, at least along its edge, application of an adhesive film extending beyond or along the strip is unnecessary. In an advantageous embodiment said coating hardens by means of UV-radiation. If this is the case, a fluid layer is applied onto the strip, for example by means of screen printing, which is then followed by the hardening thereof by means of UV-radiation, e.g. by means of flash treatment. Subsequently, a next layer may be applied onto the layer first applied onto the strip by performing the same activities. Contrary to the case requiring thermal hardening of the layer, applying a layer which hardens by means of UV-radiation will not affect the layer underneath which is already present. In an advantageous embodiment the coating comprises polyurethane, polyamide or polyvinyl chloride. Since the strip pore size is generally selected in such a way that micro-organisms, e.g. fungi and algae, are blocked, it is preferred to treat the strip with an agent against fungi and algae, thus preventing them from finding a medium for excess growth. In addition, the present invention concerns a synthetic cavity plate comprising at least two basically parallel synthetic plates which are kept at a distance by means of dividing walls, thus enclosing a number of elongated channels, the ends of which are sealed dust-proof, yet water and water vapour permeable and ventilating. This synthetic cavity plate is characterised in that its channels are sealed by applying a strip according to the present invention. The invention will be explained in more detail by means of the drawing annexed, in which: figure 1 shows a schematic view of cavity plate, the leading end of which can be sealed by the strip according to the present invention; figure 2 shows a schematic view of a strip according to the prior art; and figure 3 shows a schematic view of a detail of the strip according to the present invention. The drawings are purely schematic and not drawn to scale. Particularly for purposes of clarity, some dimensions have been represented in a greatly exaggerated manner. Whenever possible, parts in the figures are indicated with the same reference number. Figure 1 shows synthetic cavity plate 1, which comprises two parallel translucent outside plates 2,3, which are kept at each other's distance by means of dividing walls 4. The translucent synthetic material comprises, for example, acrylic plastic or polycarbonate, commercially available under the name 'Plexiglass' or 'Lexan'. The outside plates 2,3 and the dividing walls 4 enclose a number of elongated cavity channels 5, which end at both sides of the cavity plate. In order to prevent dust particles and micro-organisms from permeating the cavity channels, the cavity channels may be sealed at their leading ends by means of a dust-proof, yet water and water vapour permeable strip. Figure 2 schematically shows a part of dust-proof yet water and water vapour permeable strip according to the prior art. This strip comprises a first strip 7 of non-woven material which is dust-proof on the one hand, yet on the other hand, ensures ventilation and water as well as water vapour discharge. A film 8, which extends beyond strip 7, has been applied onto this first strip 7 and has been provided with an adhesive layer to adhere the film 8 to first strip 7 and to adhere the assembly around the edge of the cavity plate. Film 8 also comprises a number of openings 9, which leave first strip 7 locally bare. Figure 2 shows an upper view of the strip. Here the shadings in the openings 9 indicate the visible part of first strip 7, while the edges of the non-visible part of the strip 7 beneath the film 8 are indicated by means of the dotted lines 7a. This figure clearly shows that beneath and next to the openings 9, a relatively large continuous surface of the strip is impermeable to air and water as well as water vapour, thus blocking ventilation and water drainage locally. As a consequence, the water will accumulate at these spots. In addition to this, film 8 extends beyond the first strip 7 over a relatively small distance at the area of the openings 9, which is indicated by means of 'x' in figure 2. This adversely affects the strength and durability of strip 7 and, in addition, might cause problems if the film comes loose from first strip 7 over this distance x. Figure 3 schematically shows a part of a strip 10 according to the present invention. Strip 10 comprises a first strip with an open-pore structure 11, which is intended to extend over the entire width of the cavity plate end, unlike the existing strip, in which specifically the film 8 is intended to extend over the entire width. According to the present invention, the first strip 10 with an open-pore structure is provided with a layer 12 which locally seals the pores completely. This layer 12 preferably comprises an air-proof and a waterproof layer of, for example, polyurethane, polyamide or polyvinyl chloride, which has been applied according to a pattern. This is preferably realised by means of screen printing. Preferably a layer 12 is applied which hardens by means of UV-radiation. With this, it is possible to apply a fluid layer by means of screen printing, which can be hardened by means of UV-radiation, for example by means of a flash treatment. Subsequently, a second layer, which hardens by means of UV-radiation, may be applied onto the hardened layer 12 without affecting the first layer 12. The various layers 12 may have different patterns, colours and constructions. Advantageously, strip 10 is provided with an adhesive layer, at least along its edges, in order to attach strip 10 to the cavity plate 1. This adhesive layer is not shown in the figures and is preferably placed at the back of strip 10. In this way, the edges of strip 10 can be attached against the outside of the outside walls 2, 3 when folding them. The pattern of layer 12 has a regular shape in figure 2; it is, of course, also possible to apply a more irregular or asymmetrical pattern. As such, the choice of pattern depends on the ventilation desired and the filter function of underlying strip 11 with an open-pore structure. Advantageously, the pattern is applied in such a way that thickenings at the edges of the cavity plate 1 are avoided when attaching strip 10 to the cavity plate 1. In this way, damage to cavity plate 1 is avoided during further handling. The application of strip 10 according to the present invention offers a dust-proof, yet water and water vapour permeable sealing of the leading ends of the cavity channels 5 across their entire surface. Contrary to the known strip, it is avoided that relatively large continuous surfaces of the leading ends are covered by impermeable material. As a result, the accumulation of moisture beneath the strip is avoided. Although the invention has merely been explained by means of an example showing the design, it may be obvious that the invention is by no means limited to this example. On the contrary, many more designs and variations are available for the expert. As referred to above, the pattern-based coating is available in various patterns and, in addition to the screen printing method, it can be designed in various ways. In addition, the invention is not limited to double-walled plates and cavity plate, the strip according to the present invention, however, may also be applied for sealing the leading ends of cavity plate which exists of more than two plates, while the plates are, again, attached to each other by means of dividing walls.

Claims: Sealing strip (10) for sealing in a dust-proof, yet ventilating manner comprising pores (11) over substantially the entire surface, which pores are dust-proof, yet water and water vapour permeable, characterized in that some of the pores in the strip are completely sealed according to a pattern (12) and in that a backside of said strip is provided with adhesive tracks at opposite longitudinal edges thereof by which said strip is capable of adhering. Sealing strip according to claim 1, characterised in that said pores are sealed by a screen print coating which is water and air impermeable and which has been provided according to said pattern. Sealing strip according to claim 2, characterized in that said coating has been hardened by means of UV-radiation. Sealing strip according claims 2 or 3, characterised in that said coating comprises polyurethane, polyamide or polyvinyl chloride. Sealing strip according to one or more of the preceding claims, characterised in that the strip comprises an agent against fungi and algae. Synthetic cavity plate (1) comprising at least two basically parallel synthetic plates (2,3) which are kept at a distance by means of dividing walls (4), thus enclosing a number of elongated channels (5) ending at a side face of said cavity plate, characterized in that said side face is sealed by a strip according to anyone of the preceding claims, adhering with said adhesive tracks to opposite plates of the cavity plate.

Inventors: HOOFT JOHANNES WILHELMUS GERAR, HOOFT, JOHANNES WILHELMUS GERARDUS
Applicants: MULTIFOIL BV, MULTIFOIL B.V.
Application year: 1997
Main classification: E04C2
IPC codes: E04C2