WO2000047401A1

WO2000047401A1 - Insulating material

Info

Publication number: WO2000047401A1
Application number: PCT/GB2000/000392
Authority: WO
Inventors: Paul Roger Argall
Original assignee: WARRINGTON VEHICLE CENTRE Ltd
Current assignee: WARRINGTON VEHICLE CENTRE Ltd
Priority date: 1999-02-10
Filing date: 2000-02-10
Publication date: 2000-08-17
Anticipated expiration: 2001-08-10
Also published as: GB0026077D0; AU2556400A; GB2351698A; GB9902866D0

Abstract

A thermally insulating, laminated construction panel material is described, the material comprising: a plastics material foam core (12) having first and second faces (14, 14), said foam core having on at least one face thereof a heat reflective coating (20); a layer (22) of an adhesive material; and a layer (26) of fibre reinforced plastics material forming a surface of said panel. The adhesive layer may include particles for heat insulation and/or (24) spacing purposes.

Description

INSULATING MATERIAL

The present invention relates to a thermally insulating material of laminated construction particularly, though not exclusively, for the construction of insulating bodies for vehicles for the transport and storage of perishable food goods for example.

For at least the last 30 years, the transport and distribution sectors of the refrigeration market have utilised vehicle bodies constructed mainly from glass reinforced plastics (GRP) sheet, plywood and polystyrene or polyurethane foam. A typical insulating body construction may comprise a laminated structure having an outer skin of 1mm thick GRP; a 4mm thick panel of plywood; a central core of 75mm thick styrene; a 4mm thick panel of plywood; and, an inner skin of 1mm thick GRP, all of the laminate layers being bonded together by an adhesive such as an epoxy resin glue for example. Such a structure is relatively heavy and produces a panel thickness in the region of at least 85mm.

All commercial vehicles need to conform to government agency regulations imposed by legislation. In the EEC all vehicles for example must have a body width no greater than 2.6m. Conventional body panel structures having a thickness of about 85mm mean that only five industry standard sized pallets of lm x 0.9m can be contained in a 7.5 tonne vehicle of 4.2mm length and 2.3mm width.

Similar considerations exist with respect to the laminated construction of flooring materials which are currently used. In addition to being thermally insulating, such flooring materials must also be strong in order both to support the goods standing thereon during transport but also to resist the stresses imposed by loading vehicles such as fork lift trucks which are driven in and out of the transport vehicles during loading and unloading thereof. Conventional flooring materials frequently comprise, as in the wall panel material: a GRP layer on the inside; typically a 25mm thick plywood layer; a 75mm foam core; a 4mm thick plywood layer; and, 1mm GRP outer skin. Metal fixing plates are also embedded in the structure to enable the floor, and the body structure which is attached thereto to be fixed to the chassis of the vehicle by, for example, bolts in known manner. Again, this conventional structure is heavy and is also prone to puncture of the inner surface due to the rough treatment which it receives in use. Such puncturing leads to water ingress which further increases weight, reduces insulating efficiency and causes degeneration of the foam core.

The ability to produce insulating bodies which are lighter in weight and which are thinner in thickness whilst retaining adequate rigidity and strength would enable more efficient use of vehicles to be achieved by either carrying more load or by less fuel consumed due to a lighter vehicle.

It is an object of the present invention to provide a body panel construction which is thermally efficient, lighter in weight and, in most circumstances, is of less volume for a given area than conventional materials.

According to one aspect of the present invention, there is provided a thermally insulating, laminated construction panel material, the material comprising: a plastics material foam core having first and second faces; said foam core having on at least one face thereof a heat reflective coating thereon; a layer of an adhesive material; and a layer of fibre reinforced plastics material forming a surface of said panel.

The layer of adhesive material may be flexible. It may comprise or be a synthetic plastics resin material, for example an epoxy resin, more particularly a flexible epoxy resin.

Optionally, the layer of adhesive material may comprise insulating material such as low density silica particles such as that sold under the Aerosil name (trade name) by the Degussa company. These particles are capable of maintaining the resin layer strong and with a high degree of thermal insulation.

Optionally, the layer of adhesive material may also contain spacing means such as glass particles for example in order to maintain a desired thickness of resin during the curing process for the complete panel which is carried under pressure. However, any other means of spacing may be used.

The foam core material is preferably high density polystyrene foam of 20 to 40 kg/m³ density. The foam may be of the extruded variety. The thickness of the foam core may generally be about 50mm, however, any desired thickness may be employed for particular applications. A thickness in the range from 25 to 100mm will generally deal with most insulating requirements.

The heat reflective coating may be aluminium or silver for example.

The foam core may also have a layer of a plastics material adjacent the at least one surface of the foam core interposed between the foam core and the heat reflective coating. It has been found that a fibre or filament material such as a nylon fabric having a polyurethane material coated thereon or impregnated therein is particularly suitable (alternative coating/impregnating materials include silicones and elastomeric polymers). This material layer may be bonded to the foam core by a suitable adhesive, for example a pressure sensitive adhesive.

The heat reflective coating may be a metallic layer applied in any known way. This reflective layer may be incorporated onto the fibre or filament based plastics material as described above which may comprise the clothing material used for the protection of fire fighters for example. The reflective layer may be silver or aluminium for example. Preferably, the reflective layer does not comprise leaf-type metallic reflective material as the leaf forms a weak interface.

The outer surface is formed by a layer of reinforced plastics material on top of the synthetic resin layer being adhered thereto by the flexible adhesive properties of the resin layer itself. Suitable materials may include glass reinforced plastics (GRP) or aramid-type fibre reinforced plastics in some applications where superior strength is required. Where GRP is used, a suitable material for forming the internal surface of a container is that known as Kemlite (trade name) sold by the Crane Kemlite Company of the USA.

Preferably, both first and second faces of said foam core material are provided with the specified layers in substantially the same order.

Panels used for the roof and walls of refrigerated containers of transport vehicles wherein both the first and second faces of a foam core of thickness 50mm are provided with the layers described may be made to a maximum thickness of about 56mm compared with the 85mm of presently used insulating panels whilst providing greater strength and superior insulation properties. Thus, known 7.5 tonne vehicles as described above in relation to the prior art may be provided with bodies which will contain six instead of five industry standard sized pallets for stacking goods thereon.

Clearly the materials of the present invention are not only suitable for use on road vehicles but for any applications where insulating properties are required such as cold room storage for example.

According to a second aspect of the present invention, there is provided a laminated construction thermally insulating panel material, the material comprising a plastics material foam core having first and second faces; the core having bonded to the first face a plywood layer; a fibre reinforced plastics material layer being bonded to the plywood layer to form an outer surface; a layer of a fibre reinforced plastics material bonded to said second face; a layer of plywood bonded to the fibre reinforced plastics material layer; a layer of a fibre reinforced plastics material bonded to the plywood layer.

In the invention according to the second aspect, one or both of the layers of fibre reinforced plastics material may comprise an aramid poly amide. At least one such layer may be covered with a layer of grit and glass resin to provide a non-skid surface. The foam core on the first face may also contain metal plates for receiving fixing means such as bolts for example for joining this material to the chassis of a truck for example.

The plywood on the first face may be about 4mm thick for example but any suitable thickness may be used.

The plywood on the side of the second face of the foam core may be about 12mm thick for example and is to bear the weight and rigours of loading vehicles such as fork lift trucks being driven on and off. However, any suitable thickness may be used commensurate with the task to be performed.

The layer of fibre reinforced plastics (FRP) material on the side of the first face may be GRP and may be about 1mm thick minimum. However, other FRP materials may be used such as aramid reinforced plastics. The side of the first face is to form the outside surface of a floor panel, i.e. the underside of a container, the surface which is not directly loaded and abraded.

The side of the second face of the foam core has an outer layer of FRP material which may be for example of aramid or GRP material. However, desirably, this side also has a further layer of FRP material which is interposed between the plywood layer and the outer GRP layer and may be an aramid reinforced plastics material. The aramid material is particularly strong and resilient and may be a minimum of about 0.5mm thick.

The outer surface of FRP material may, as mentioned above, be of GRP material and which may also possess a grit surface coating for slip resistance.

The material of the second aspect is particularly suitable for floor panels of vehicles, being strong and abrasion resistant. A floor panel of about 90 to 93mm in thickness may be made having lighter weight greater strength than a conventional floor of about 110mm thickness. In order that the present invention may be more fully understood, examples will now be described by way of illustration only with reference to the accompanying drawings, of which:

Figure 1 shows a cross section through an insulating panel suitable for the walls and roof of an insulating container or cold room; and

Figure 2 which shows a cross section through an insulating panel suitable for the floor of an insulating container.

Figure 1 shows a cross section through part of an insulating panel 10 according to one embodiment of the present invention suitable for the manufacture of the side walls and roof of a container for the refrigerated transport or storage of perishable goods. The panel 10 comprises a central core 12 of 50mm thick high density extruded polystyrene foam commonly used in the building industry for insulation purposes. To each face 14, a layer 16 (shown as a thicker black line) of a suitable adhesive, for example a pressure sensitive adhesive such as a water-based acrylic co- polymer, bonds a layer of a polyurethane coated nylon fabric 18. On top of the layer 18 is a coating of a heat reflective material 20 such as silver or aluminium. In this case, the layer 18 also includes the reflective surface 20 formed thereon. Material 18 is a cloth similar to that used for the manufacture of protective clothing or an insulation barrier for example. To the heat reflective layers 20 are applied a layer 22 of a suitable adhesive to bond layer 18 through to layer 26. Mixed with the resin are particles of material having high thermal insulation properties. In this case the particles are of fumed silica sold under the trade name Aerosil and constitute about 9 weight per cent of the layer 22. Also included in the layer 22 are particles 24 which may be present as spacers so as to maintain the thickness of the layer 22 by preventing it from being squeezed out during curing under pressure. Clearly, the layers 22 may each have a different thickness on each side of the panel and different sized particles 24 or other spacer means may be used as desired. Any other suitable spacer means may be used as desired such that the insulating qualities of the adhesive layers 22 are not seriously degraded. On the outer surfaces of the layers 22 are layers 26 of GRP to confer strength and wear/abrasion resistance. These outer layers 26 may be different. For example, the layer on the inner surface of the container made from the panels may be of Kemlite (trade name) which has a good abrasion resistance and is easy to clean.

A panel as described above may be made with a thickness of about 56mm compared with 85mm for conventional material. However, the insulating ability, weight and strength of the material according to the present invention is equal if not superior in every respect to the conventional material.

In variants of Figure 1, the heat insulating particles and/or the spacers 24 are omitted from one or both layers 22.

Figure 2 shows another embodiment of the present invention where a cross section of part of a panel 30 suitable for the floor of a transport vehicle is shown. The panel 30 comprises a plastics foam core 32 of material similar to that of Figure 1 but of 75mm thickness in this case. On a first face 34 is bonded a layer of plywood 36 of about 4mm thickness to the outer surface of which is bonded a layer of FRP material 38, in this case, a GRP material of about 1mm minimum thickness. Steel plates 40 are let into the foam core 32 on the first face to receive fixing bolts (not shown) to attach the panel to the chassis of a truck (not shown) for example. A layer 42 of FRP, in this case GRP, is bonded to the second face 44 of the foam core 32. A layer of plywood 46 about 12mm thick is bonded to the FRP layer 42. A layer or layers 48 of aramid reinforced plastics material is bonded to the outer face of the plywood layer. Aramid materials such as Kevlar (Trade name), Twaron (Trade name) and Monsanto X500 (Trade name) may be used. An outer layer 50 of FRP, in this case, GRP-resin having a grit glass resin surface 52 is bonded to the FRP layer 48. The purpose of the GRP layer adjacent the second face 44 is to provide a barrier to water ingress into the foam core should the outer FRP layers 48, 50 and the plywood layer 46 become punctured. The layers 26 of Figure 1 may be of different thicknesses and/or constituents and may comprise GRP, aramid reinforced resin, aluminium sheet or, in some cases, steel for example.

Claims

1. A thermally insulating, laminated construction panel material, the material comprising: a plastics material foam core having first and second faces; said foam core having on at least one face thereof a heat reflective coating thereon; a layer of an adhesive material; and a layer of fibre reinforced plastics material forming a surface of said panel.

2. A material according to claim 1 wherein the foam core material is high density polystyrene foam of 20 to 40 kg/m³ density.

3. A material according to either claim 1 or claim 2 wherein the foam is of the extruded variety.

4. A material according to any one preceding claim wherein the thickness of the foam core is in the range from 25 to 100mm.

5. A material according to any one preceding claim wherein the heat reflective coating is aluminium or silver.

6. A material according to any one preceding claim wherein the foam core also has a layer of a plastics material adjacent the at least one surface of the foam core interposed between the foam core and the heat reflective coating.

7. A material according to claim 6 wherein the plastics material is a fibre or filament material such as a nylon fabric having a polyurethane coating thereon or impregnated therein.

8. A material according to claim 7 wherein the plastics material layer is bonded to the foam core by a suitable adhesive.

9. A material according to any one of preceding claims 6 to 8 wherein the heat reflective coating is a silvered or aluminised urethane layer incorporated onto the fibre or filament based plastics material.

10. A material according to any one preceding claim wherein the layer of adhesive material comprises synthetic plastics resin material.

11. A material according to claim 10 wherein the synthetic plastics resin material comprises a flexible epoxy resin.

12. A material according to any one preceding claim wherein the layer of adhesive material also contains heat insulating particles.

13. A material according to claim 11 wherein the heat insulating particles comprise low density silica particles.

14. A material according to any one preceding claim wherein the layer of adhesive material also contains spacing means.

15. A material according to any one preceding claim wherein both faces of the foam core have the layers specified in the preceding claims.

16. A wall panel for an insulating vehicle container when made of the laminate material of any one of preceding claims 1 to 15.

17. A laminated construction thermally insulating panel material, the material comprising a plastics material foam core having first and second faces; the core having bonded to the first face a plywood layer; a fibre reinforced plastics material layer being bonded to the plywood layer to form an outer surface; a layer of a fibre reinforced plastics material bonded to said second face; a layer of plywood bonded to the fibre reinforced plastics material layer; a layer of a fibre reinforced plastics material bonded to the plywood layer.

18. A material according to claim 17 wherein the foam core on the first face also contains metal plates for receiving fixing means for joining the material to a structure.

19. A material according to either claim 17 or claim 18 wherein the side of the second face also has a further layer of FRP material which is interposed between the plywood layer and the outer FRP layer.

20. A material according to claim 19 wherein the further layer is an aramid reinforced plastics material.

21. A material according to any one of preceding claims 17 to 20 wherein the outer layer on the side of the second face also has a grit surface coating for slip resistance.