GB2471703A

GB2471703A - Multilayer plastic glazing panel

Info

Publication number: GB2471703A
Application number: GB0911939A
Authority: GB
Inventors: David John Anderson
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-07-09
Filing date: 2009-07-09
Publication date: 2011-01-12
Also published as: GB0911939D0

Abstract

The glazing panel comprises a first layer 52 and a second layer 54 and a number of ribs 56 connecting the first and second layers together which define a number of cavities 60 between the first and second layers, a third layer 64, is secured to the first layer such that the second and third layers define the facing surfaces of the panel. The third layer may include a heat or light reflecting dye and an ultraviolet filter or be heat absorbing. The third layer may be made from PVC and may have a lower resonant frequency relative to the panel with just the other layers, which may be made from polycarbonate, such that when the third layer is secured to the first layer the entire panel has a lower resonant frequency. The third layer may be secured by bonding or a peripheral securing device and may also be acoustically isolated from the first layer. Also claimed are a roof and method for constructing the panel.

Description

Plastics Glazing Panels

Field of the Invention

The invention relates to plastics glazing and particularly, but not exclusively, to plastics glazing panels for roofing such as roofing of conservatories.

Background to the Invention

It is known to upgrade existing glazing installations that have glass glazing panels by applying window film products on the inner or outer face of the glass. The film may be clear or tinted and may include reflecting metals to provide protection from solar heat, glare or ultra violet or microwave radiation and to retain heat to maintain room temperature during winter. The preferred construction for excluding solar heat, providing enhanced winter insulation and a shield against microwave radiation (such as mobile phone signals) is to include a reflecting metal in the film. One side of the film is provided with an adhesive. As an alternative to providing a metal layer, a tint may be incorporated in the film or the adhesive.

It is also known to provide window films that do not include a metal layer or tint.

Such films are essentially just clear and may improve glass safety by helping to prevent shattering.

All such films typically include ultraviolet filters to stabilise the film and/or prevent fading of furnishings and other items that are located behind the glazing panel to which the film is applied.

A typical window film provided with a reflecting metal comprises a reflecting metal foil sandwiched between two layers of polyester film. Such window films are usually supplied in rolls having nominal widths in the range of 600 to 1200mm and a nominal thickness in the range 20 to 200 microns. In order to apply such a film to a glass panel of a glazing installation, the film is first cut to match the exposed surface area of the glass so that it can be fitted within the inner perimeter of the frame that supports the glass. The film is then bonded to the glass using a water-based system. The film is floated onto the glass panel and once in position is fixed in place by expelling the water using a squeegee. This enables the adhesive to make contact with and bond to the glass.

Referring to Figure 1, known glazed roof structures often make use of plastics cellular glazing panels 10 that comprise a first outer layer 12 and a second outer layer 14 and a plurality of internal ribs 16 connected with the first and second outer layers to define a plurality of chambers, or cells, 18 between the layers. The cells 18 typically contain nothing but air, which serves as an insulator. Such glazing panels may be made of a polycarbonate and formed by an extrusion process.

Window films for use on glass are not suitable for application to plastics cellular glazing panels such as the cellular glazing panels 10 described above. There are two main reasons for this. Firstly, the exterior major surfaces 20, 22 of the cellular glazing panel that are defined by the first and second outer layers 12, 14 are not flat.

As shown in somewhat exaggerated form in Figure 1, there tends to be a slight rise between each point at which the layers 12, 14 connect with an internal rib 16.

Secondly, the internal ribs 16 are not of uniform thickness. Some are structural components and are relatively thick to provide rigidity and strength, while others simply subdivide the space between the outer layers to create the cells 18 and are much thinner as they have no structural function.

Due to the undulations in the exterior major surfaces 20, 22 of plastics cellular glazing panels 10, it is difficult to obtain a satisfactory bond between a window film and the glazing panel. Furthermore, at least in part due to the different thicknesses of the internal ribs 16, the coefficient of expansion of the glazing panel is non-uniform.

Thus, when the glazing panel 10 heats up during the day, parts of the film will be stretched, often resulting in adhesive slippage. Adhesive slippage does not reverse as the parts contract on cooling. This results in bunching of the film, leading to the presence of fingers and bubbles in the film. This is not aesthetically pleasing and areas of non-adhesion may provide technical problems as water ingress into the bubbles and fingers can result in the deterioration of the film. This is due to the retained water causing lifting of the film and the combined effect of ultraviolet rays and the moist conditions between the film and the glazing panel.

Known plastics cellular glazing panels may incorporate a tint for absorbing solar energy. Because the solar tint runs all the way through, or at least runs through a significant part of the sheet, such panels are not particularly effective at excluding heat. This is because heat is absorbed throughout, or substantially throughout, the glazing panel. As a consequence, the whole of the glazing panel heats up and the reduction in temperatures within the space enclosed by the structure incorporating the glazing panel is insufficient to provide comfort for occupants of the space.

Summary of the Invention

The invention provides a plastics glazing panel comprising a first layer, a second layer, a plurality of ribs connected with said first and second layers for dividing a space between said first and second layers into a plurality of cavities and a third layer secured to said first layer, said second and third layers defining oppositely facing major surfaces of the glazing panel and said third layer comprising a glazing sheet that is at least semi-rigid.

The invention also includes a composite plastics glazing panel comprising a hollow plastics glazing panel and a plastics sheet secured to said hollow plastics glazing panel, said plastics sheet being at least semi-rigid and defining a major exterior surface of the composite glazing panel.

The invention also includes a method of manufacturing a plastics glazing panel, said method comprising securing a plastics sheet to a hollow plastics glazing panel such that said plastics sheet defines a major exterior surface of the glazing panel.

Brief Description of the Drawings

In order that the invention may be well understood, an embodiments thereof, which is given by way of example only, will now be described with reference to the drawings in which: Figure 1 is a schematic side elevation of a prior art cellular glazing panel; and Figure 2 is a schematic side elevation of a plastics glazing panel according to the invention.

Detailed Description of the Illustrated Embodiment

Figure 2 is a schematic side elevation of a plastics glazing panel 50 in accordance with the invention. Tt is to be understood that the drawing is not intended to be an accurate representation of the proportions of the parts of the glazing panel and that for ease of representation some parts are shown somewhat out of scale.

The glazing panel 50 comprises a first layer 52, second layer 54 and a plurality of ribs 56, 58 disposed between the first and second layers. The ribs 56 connect the first and second layers and are structural members of the glazing panel 50. Accordingly, the ribs 56 are relatively thick and sized to provide the desired strength and rigidity to the panel. The ribs 58 extend transverse to the ribs 56. Because they are not intended to perform a structural function, the ribs 58 are relatively thin, as compared with the ribs 56. The ribs 56, 58 cooperate with the first and second layers 52, 54 to define a plurality of cells, or cavities, 60 containing air that serves as an insulator. In the illustrated embodiments, the ribs 56 are perpendicular to the respective planes of the first and second layers 52, 54 and the ribs 58 are perpendicular to the ribs 56. It is to be understood that this is not essential. For example, at least some of the ribs 56 and/or ribs 58 may be inclined to the first and second layers 52, 54.

It will be noted that the second layer 54 defines a major exterior surface 62 of the glazing panel 50 that comprises undulations in the same way as the first and second layers of the known cellular glazing panel 10 shown in Figure 1.

The first and second layers 52, 54 and ribs 56, 58 are integral and, for ease of reference, in the description that follows may be referred to as the basic unit. The basic unit may, for example, be made of polycarbonate, polyvinylchoride (PVC), polymethylmethacrylate or polyester. In general, the first and second layers 52, 54 are relatively thin (for example they may be approximately 1mm thick) and the ribs 56, 58 may be thinner still.

The glazing panel 50 comprises a third layer 64 that is secured to the first layer 52 (the dashed line in Figure 2 indicates an idealised join line between the two layers, although in practice, depending at least in part on the way in which the two layers are joined, it may not be possible to discern any such join line). The third layer 64 defines a major exterior surface 66 of the glazing panel 50. In the illustrated embodiment, the third layer 64 is bonded to the first layer 52. This can be achieved by heating the surfaces of the two layers 52, 64 that are to be joined prior to bringing them into contact so that the two layers are melded or fused to one another. The surfaces may be heated by any convenient known method including the use of radio frequency or ultrasonic techniques. Alternatively, the third layer 64 can be pressed onto the first layer 52 at, or adjacent, the exit of an extruder from which the basic unit is extruded. In this way, it is possible to utilise the heat of extrusion and thereby reduce the energy input required for the manufacturing process. As yet another alternative, the basic unit and third layer can be co extruded.

As an alternative to bonding the third layer 64 to the first layer 52 by means of heating techniques, the two layers may be joined by means of an adhesive. Yet another alternative would be to apply a surface modifier (for example a solvent) to one or both of the surfaces to be joined to chemically modify the surface(s) in such a way that they would bond on making contact. In either case, it may be desirable to apply pressure to the basic unit and third layer during the bonding process.

In the illustrated embodiment, the third layer 64 is a rigid, or at least semi-rigid, plastics sheet that has a film 68 on the major exterior surface 66. The film 68 may incorporate a heat reflecting foil, tints, dyes and/or an ultra violet filter. The heat reflecting foil (not shown) can serve to reflect solar heat away from a glazed structure to prevent undesired heating and reflects heat into the structure to prevent undesired heat loss. The heat reflecting foil may be a metal foil, for example, an aluminium, stainless steel, gold, chrome, or other metal foil with ultra-violet, light, infra red or micro-wave reflecting characteristics having a thickness in the range that provides transparency to achieve light transmission of 0 to 80 %. The exact thickness will depend upon the metal used and the exact wavelength of radiation that is to be reflected or transmitted. In general the thickness will range from 0.5 to 200 Angstroms preferably 3 to 20 Angstroms.

As an alternative to applying a film 68 to the third layer 64, the enhancements provided by the film may be incorporated directly into the third layer. For example, the third layer 64 may be a single sheet in which a heat reflecting metal foil is embedded during manufacture or a sandwich construction comprising two or more layers of plastics material with one or more layers of metal foil sandwiched between them.

The third layer 64 may have a nominal thickness t in the range 1 to 12mm. It is presently anticipated that a preferred range would have a nominal thickness in the range 1 to 6mm. The plastics from which the third layer 64 is formed may be transparent or semi transparent (translucent). While not limited to such materials, the third layer may be a polycarbonate, polyvinylchoride (PVC), polymethylmethacrylate, polyester, polypropylene, polystyrene, or polyvinylfluoride and may incorporate ultra violet filters to protect the glazing panel against degradation due to exposure to the environment and/or tints to reduce glare.

it will be appreciated that the provision of the third layer provides the glazing panel with sufficient strength and rigidity to avoid the expansion and contraction problems associated with the prior art plastics glazing panels exemplified by the glazing panel shown in Figure 1. Furthermore, it also allows the provision of a major surface that is considerably flatter than the major surfaces 20, 22 shown in Figure 1. Accordingly, a film, such as the film 68 can be used on the plastics glazing panel 50 with better results than are obtained when using such a film on known plastics cellular glazing panels. Alternatively, it is possible to integrate the enhancements provided by such films directly into the third layer.

Hollow polycarbonate roofing structures are notorious for the drumming sound that they emit when it is raining. The noise can be so loud as to drown out speech. This factor limits the market for these roof structures. It has been found in tests that embodiments of the plastics glazing panel can at least reduce the drumming sound to allow the area below the conservatory or roof to be used in comfort. This is because the presence of the third layer alters the sonic/acoustic properties of the glazing panel as compared with a panel comprising just the basic unit. The properties of the glazing panel can be tuned, by for example selection of the material used to form the third layer so to enhance the sound deadening effect of the third layer. For this purpose, it may be preferred to have a third layer made of a plastics material that is softer than that of the basic unit to which it is secured. For example, if the basic unit is made of a polycarbonate, a third layer comprising polyvinylchloride (PVC) sheeting has been found to produce good results. II is generally preferred that the third layer has a lower resonant frequency than the basic unit it is fixed to.

It will be understood that the third layer may be provided simply to tune the sonic/acoustic properties of the glazing panel and so does not have to include a material(s) that will provide protection heat reflection, light reflection or radiation protection or a film such as the film 68. For this purpose, the third layer may simply be a rigid or semi-rigid transparent or translucent plastics sheet.

In addition to reducing the noise levels resulting from the impact of rain on the glazing panel, the provision of the third layer will generally improve the ability of the glazing panel to block external noise. Measurements on embodiments of the glazing panel has shown a reduction of 20 db or more depending on the thickness of the third layer and the material from which it is made and on the frequency of the sound. It will be understood that a thicker third layer may be better able to absorb the impact of the rainfall.

It will be appreciated that the third layer may be secured to the first layer of the basic unit by a variety of methods other than bonding. For example, the third layer may be secured to the basic unit by clamping, a clip arrangement, tape or a combination of these. it will be understood that where such techniques are used, if the glazing panel has to be cut to size, it may be necessary to, at least in part remake the join after the cutting operation.

It is believed that better acoustic properties may be obtained if the third layer is at least in part acoustically isolated from the basic unit. This effect is readily achievable if the third layer is secured to the basic unit by clamps, clips, tapes or the like since the securing forces will typically be applied only around the periphery of the glazing panel. Where the third layer is secured to the basic unit by bonding, whether using heat, adhesives or chemical modifiers, the same result can be achieved if the bonding between the third layer and basic unit is not over the entire extent of their opposed faces, but for example, is only around the periphery of the glazing panel.

Alternatively, or additionally, the adhesive used may be one that provides a vibration absorbing connection between the two parts.

II will be appreciated that the third layer provides the possibility of reducing the noise transmitted by the glazing panel, as compared with a basic unit not having the third layer. The reduction in noise transmission may be due to one, or a combination, of 1) the bond between the third layer and basic unit being one that the properties of the third layer produce a composite glazing panel having a lower resonant frequency than the basic unit by itself; 2) having a thicker side providing a major exterior surface of the glazing panel, which is better able to absorb the impact of rainfall and the like than is the first of second layer of the basic unit; 3) having a third layer that is made from a softer material than the material from which the basic unit is made; and 4) providing for some acoustic separation between the basic unit and third layer.

The third layer and/or film (where provided) may include heat absorbing materials and/or tints for absorbing solar energy, typically in the wavelength range 800 to 3000 nanometres. A third layer so provided can be combined with a basic unit to provide a composite glazing panel having heat absorbing materials and/or tints concentrated in what can serve as an outer surface/layer of a glazed structure. The result should be that a greater proportion of the solar heat absorbed by the glazing panel is dissipated to the outside air than would be the case with a known cellular plastics glazing panel provided with heat absorbing tints, thereby providing the possibility of a worthwhile reduction in temperatures within a space enclosed by a structure incorporating the composite glazing panel. The benefit obtained may be enhanced if the third layer is secured to the basic unit in such a way as to provide some degree of resistance to heat conduction between them. Thus, for example, it may be preferable to secure the third layer to the basic unit by clamping, a clip arrangement, tape or a combination of these, or where securing is by bonding, by bonding in such a way that the bond is not over the entire extent of the opposed faces of the two parts. Where securing is by bonding, an adhesive having poor heat conduction properties could be used. Alternatively, or additionally, the benefit may be enhanced if the basic unit has high insulation values.

High insulation values can be obtained by increasing the thickness of the basic unit and/or increasing the number of cells defined between its exterior layers.

II will be appreciated that in embodiments in which a film, such as the film 68, is provided on the third layer, the third layer may be secured to the basic unit such that the film is between the basic unit and third layer. Since this configuration allows the third layer to protect the film from the external environment, it is possible to use lower quality and cheaper films than if the film is to form the external surface of the glazing panel in the way shown in Figure 2.

It is believed generally preferable that the third layer is added to the basic unit, and when used the film is added to the third layer, at a place of manufacture and that the composite glazing panel thus formed is sent to construction sites. However, in principle, the third layer could be secured to the basic unit on site and equally, a film could be fitted to the third layer on site.

Claims

Claims 1. A plastics glazing panel comprising a first layer, a second layer, a plurality of ribs connected with said first and second layers for dividing a space between said first and second layers into a plurality of cavities and a third layer secured to said first layer, said second and third layers defining oppositely facing major surfaces of the glazing panel and said third layer comprising a glazing sheet that is at least semi-rigid.
2. A plastics glazing panel as claimed in claim 1, wherein said third layer includes at least one heat and/or light reflecting material.
3. A plastics glazing panel as claimed in claim 1 or 2, wherein said third layer includes a tint or a dye.
4. A plastics glazing panel as claimed in claim 1, 2 or 3, wherein said third layer includes an ultra violet filter.
5. A plastics glazing panel as claimed in any one of the preceding claims, wherein said third layer comprises a heat absorbing tint and/or heat absorbing material.
6. A plastic glazing panel as claimed in any one of the preceding claims, wherein said third layer has a thickness greater than said first layer.
7. A plastics glazing panel as claimed in any one of the preceding claims wherein said third layer comprises rigid or semi-rigid plastics sheeting bonded to said first layer.
8. A plastics glazing panel as claimed in any one of the preceding claims, wherein said third layer is made from a material that is softer than the material from which the first layer is made.
9. A plastics glazing panel as claimed in any one of the preceding claims, wherein said first layer, second layer and ribs have a first resonant frequency absent said third layer and said third layer has a second resonant frequency that is lower than said first resonant frequency such that when said third layer is secured to said first layer said glazing panel has a resonant frequency lower than said first resonant frequency.
10. A plastics glazing panel as claimed in any one of claims 1 to 8, wherein said third layer is secured to said first layer such that said third layer is at least in part substantially acoustically and/or isolated from said first layer.
11. A plastic glazing panel as claimed in any one of the preceding claims, wherein said first layer, second layer and ribs are a polycarbonate extrusion and said third layer comprises PVC sheeting secured to said first layer.
12. A composite plastics glazing panel comprising a hollow plastics glazing panel and a plastics sheet secured to said hollow plastics glazing panel, said plastics sheet being at least semi-rigid and defining a major exterior surface of the composite glazing panel.
13. A composite plastics glazing panel as claimed in claim 12, wherein said plastics sheet is releasably secured to said hollow plastics glazing panel by a peripheral securing device.
14. A composite plastics glazing panel as claimed in claim 12, wherein said plastics sheet is secured to said hollow plastics glazing panel by bonding by application to at least one of said plastics sheet and said hollow plastics glazing panel: 1) energy causing heating; 2) an adhesive; and 3) a surface modifier.
15. A composite plastics glazing panel as claimed in claim 12, 13 or 14, wherein said plastics sheet incorporates a heat absorbing material and/or tint.
16. A composite plastics glazing panel as claimed in any one of claims 12 to 15, wherein said plastics sheet is secured to said hollow plastics glazing panel such that thermal conduction therebetween is at least partially impeded.
17. A roofing structure comprising at least one glazing panel as claimed in any one of the preceding claims.
18. A method of manufacturing a plastics glazing panel, said method comprising securing plastics sheeting to a hollow glazing panel such that said plastics sheeting defines a major exterior surface of the glazing panel.
19. A method of manufacturing a plastics glazing panel as claimed in claim 18, comprising bonding a surface of said hollow glazing panel to a surface of said plastics sheeting.
20. A method of manufacturing a plastics glazing panel as claimed in claim 19, wherein at least one of said surfaces is heated to facilitate bonding.
21. A method of manufacturing a plastics glazing panel as claimed in claim 19 or 20, wherein an adhesive or surface modifier is applied to at least one of said surfaces to facilitate bonding.
22. A method of manufacturing a plastics glazing panel as claimed in any one of claims 18 to 21, wherein said hollow glazing panel has a resonant frequency and said plastics sheeting has a resonant frequency lower than said resonant frequency of the hollow glazing panel such that the plastics glazing panel has a lower resonant frequency than said hollow glazing panel.
23. A method of manufacturing a plastics glazing panel as claimed in any one of claims 18 to 21, comprising securing said plastics sheeting to said hollow glazing panel such that said plastics sheeting is at least in part at least substantially acoustically isolated from said hollow glazing panel.
24. A method of manufacturing a plastics glazing panel as claimed in any one of claims 18 to 23, wherein said plastics sheeting is made from a material that is softer than a material from which said hollow glazing panel is made.
25. A method of manufacturing a plastics glazing panel as claimed in claim 24, wherein said hollow glazing panel is made from polycarbonate and said plastics sheeting is made from PVC.
26. A method of manufacturing a plastics glazing panel as claimed in any one of claims 18 to 25, wherein said third layer includes at least one of: -a heat reflecting foil; -an ultraviolet filter; and -a dye, tint or heat absorbing material.
27. A method of manufacturing a plastics glazing panel as claimed in any one of claims 18 to 26, comprising providing a film on said major surface defined by said plastics sheeting, said film including at least one of: -a heat reflecting foil; -an ultraviolet filter; and -a dye, tint or heat absorbing material.
28. A plastics glazing sheet substantially as herein described with reference to Figure 2.
29. A method of manufacturing a plastics glazing panel substantially as herein described with reference to Figure 2.