IES83842Y1 - A composite insulating panel and its method of manufacture - Google Patents

Abstract

ABSTRACT A method for manufacturing a composite insulating panel of the type comprising an external metal skin, an internal metal skin and an insulating core of foam material therebetween, the method includes the steps of:- conveying one of the metal skins continuously along a flatbed with an outer surface of the skin lowermost; laying down liquid insulating foam reactants onto the first skin; leading the second metal skin continuously over the liquid insulating foam reactants and the first metal skin; heating the assembly in an oven to allow the foam reactants to expand to form an insulating core between the metal skins; cutting the panel to a desired length, and applying a seal to at least one of the exposed foam edges of the panel. The seal which comprises a gas and/or vapour barrier is applied in-line.

Description

“A composite insulating panel and its method of manufacture” Introduetion The invention relates to a panel of the type comprising an external sheet and a backing sheet with an insulating foam core therebetween.

Over time diffusion of gas/vapour from insulating panels often results in decreased thermal conductivity. To cater for this in production, an insulating panel is manufactured to the required thickness to provide the desired insulating properties taking account of estimated the effects of ageing on the insulating properties of a panel when installed in a particular operational environment. This is generally inefficient and wasteful.

The present invention addresses these problems.

Statements of Invention According to the invention there is provided a method for manufacturing a composite insulating panel of the type comprising an external metal skin, an internal metal skin and an insulating core of foam material therebetween, the method includes the steps of: - conveying one of the metal skins continuously along a flat bed with an outer surface of the skin lowermost; laying down liquid insulating foam reactants onto the first skin; leading the second metal skin continuously over the liquid insulating foam reactants and the first metal skin; heating the assembly in an oven to allow the foam reactants to expand to form an insulating core between the metal skins; cutting the panel to a desired length, and applying a seal to at least one of the exposed foam edges of the panel.

In one embodiment the method comprises the step of removing dust from the exposed foam edge prior to application of the seal.

The dust may be removed from the exposed foam edge by the application of suction.

Alternatively or additionally the exposed foam edge is brushed to remove dust.

In one embodiment the seal is applied in—line.

In another embodiment the seal comprises a gas and/or vapour barrier.

In one embodiment the method includes the step of applying a seal in the form of a strip of film, membrane or tape to the exposed edge of the panel. Preferably the strip is retained in place by adhesive bonding.

In one embodiment the method includes the step of applying a seal forming liquid to the exposed edge of the panel. Preferably the liquid is applied by spaying or by coating.

In one embodiment the seal comprises a polymeric material, preferably the polymeric material is polyvinylidene chloride or polyvinyl alcohol or polyvinyl chloride.

In another embodiment the seal comprises a thermoplastics material.

In a further embodiment the seal comprises a foil. The seal may comprise a metallic foil. In a preferred embodiment the seal comprises an Aluminium foil.

In another embodiment the seal comprises a laminate foil comprising polymeric material with a metallic coating. Preferably the metallic material is Aluminium.

According to another aspect of the invention there is provided an insulating panel comprising an external metal skin, an internal metal skin and an insulating core of foam material therebetween, the panel having at least one cut edge and the panel having a seal applied to the cut foam edge.

In one embodiment the panel has two opposed cut edges and a seal is applied to both out edges.

In another embodiment the seal comprises a gas and/or vapour barrier.

In one embodiment the seal is in the form of a strip of film, membrane or tape.

Preferably the strip is retained in place by adhesive bonding.

In one embodiment the seal is comprised of a seal forming liquid. Preferably the liquid is applied by spaying or by coating.

In another embodiment the seal comprises a polymeric material. Preferably the polymeric material is polyvinylidene chloride or polyvinyl alcohol or polyvinyl chloride.

In one embodiment the seal comprises a foil. Preferably the seal comprises a metallic foil. Most preferably the seal comprises an Aluminium foil.

In another embodiment the seal comprises a laminate foil comprising polymeric material with a metallic coating. Preferably the metallic material is Aluminium.

In a further embodiment the seal comprises a thermoplastics material.

Description of Drawings The invention will be more clearly understood from the following description thereof given by way of example only with reference to the accompanying drawings, in which Fig. 1 is a transverse cross sectional view of a panel of the invention; Fig. 2 is a side view of a part of an apparatus used in the method of the invention; and Fig. 3 is a side view of an alternative apparatus used in the method of the invention.

Detailed Description Referring to Figs. 1 and 2 a composite insulating panel 1 comprises an external metal skin 2, an internal metal skin 3, and an insulating core 4 of foam between the skins 2, 3. Both skins 2, 3 may be of steel material and are usually profiled to a desired profile shape. The insulated panel 1 is typically used for roofing and/or wall cladding, partitions, compartmental wall panels, cold store panels, clean room envelopes, food processing areas and the like applications, particularly where added fire resistance is required. The insulating panels 1 are manufactured by first conveying one of the metal skins 2 continuously along a flat bed with an outer surface of the skin 2 lowermost. Liquid insulating foam reactants including a blowing agent are then laid down through a lay down device such as a poker 20 onto the first skin 1. The second skin 3 is laid continuously over the liquid insulating foam reactants and the first metal skin 2. The assembly thus formed is then heated in an oven 21 to allow the foam reactants to expand to form an insulating core 4 between the metal skins 2.3. The continuous panel thus formed is then cut to a desired length using an in-line saw 22.

The top and bottom edges 5 and 6 of the resulting cut panel are exposed. Referring to Fig. 3 in a preferred arrangement any dust remaining on the cut edge is first removed in steps 25. For example, a suction may be applied to suck up the dust and/or the edge may be brushed. These dust removal step(s) 25 may be carried out in-line. They ensure that the cut edge is prepared to receive and bond with the applied seal. A seal 7 is applied to at least one of the exposed cut edges 5, 6 of the panel. The seal 7 is a gas and/or vapour impermeable seal.

An in—line sealing means 23 may be used to apply the seal 7 to the exposed edges.

At least one of the top and bottom edges 5, 6 of the panels, which are exposed when the panel is cut, are sealed by the in—line sealing means 23 to prevent the diffusion out of the blowing agent used in the manufacture of the panel. The seal 7 forms a gas or vapour barrier on the panel. The seal 7 may comprise a membrane or film strip or tape, which is continually applied to the cut edge of the panel.

The seal 7 may alternatively be in the form of an aqueous emulsion applied by spraying or coating onto the edges onto the exposed panel edges.

Suitable seals include: Aluminium foil, or a foil of polymeric material coated with Al.

Foils, membranes or emulsions comprising a polymeric material for example polyvinylidene chloride (PVDC) from Solvay or Dow, polyvinyl alcohol (PVOH), polyvinyl chloride (PVC), or laminated foils or membranes comprised of polymeric and metallic layers. It will be appreciated that seals of any suitable thermoplastics material may the used.

The panel comprises an insulating foam with high insulating properties. Insulating foams with a closed cell structure are particularly suitable. Polyisocyanurate for example has the desired closed cell structure for good thermal conductivity. The choice of blowing agent used in the manufacturing process effects the thermal conductivity of the panel. In addition, over time the blowing agent escapes from the foam and is replaced by air, with the effect of reduced thermal conductivity. During the ageing process changes in the internal cell gas pressure result in reduced thermal conductivity.

The steel faced insulated polyisocyanurate panels thus produced have excellent structural properties and a high thermal conductivity.

Panels may be readily produced in any desired length, width or thickness.

Example: Comparative measurements of the thermal conductivity of polyisocyanurate steel faced panels were taken after ageing the panels for 25 weeks at 70°C. The edges of one set of panels were sealed with Aluminium foil. The edges of the second set were not sealed.

The panels were of dimensions 500x500x80mm. Sections of dimensions 250x250x25mm were cut from the middles of the panels and the thermal conductivity measured. The effect of different blowing agents use was also considered.

Blowing Initial K value Aged K Value Aged K Value Agent W/mK (unsealed) (sealed) W/mK W/mK 141b 0.0184 0.0192 0.0188 365/227 0.0190 0.0201 0.0192 Water blown 0.0215 0.0232 0.0214 Thus the panels with exposed edges sealed have superior thermal properties.

The sealed panels provide more stable K values irrespective of blowing agent used.

The invention provides a method of production of sealed panels with improved thermal conduction and K value. The invention further provides for the provision of panels with the required levels of thermal conductivity which have a reduced thickness in comparison with panels that are currently in use.

The invention provides an extremely efficient factory scale process for manufacturing high quality composite Steel faced PIR panels on a continuous basis. Thus, the unit costs of production of such panels is minimised.

The invention is not limited to the embodiments hereinbefore described which may be varied in detail.

Claims (4)

1. A method for manufacturing a composite insulating panel of the type comprising an external metal skin, an internal metal skin and an insulating core of foam material therebetween, the method includes the steps of :- conveying a first metal skin continuously along a flat bed with an outer surface of the skin lowermost: laying down liquid insulating foam reactants onto the first skin: leading the second metal skin continuously over the liquid insulating foam reactants and the first metal skin; heating the assembly in an oven to allow the foam reactants to expand to form an insulating core between the metal skins; cutting the panel to a desired length, and applying a seal to at least one of the exposed foam edges of the panel.

2. A method as claimed in claim 1 comprising the step of removing dust from the exposed foam edge prior to application of the seal, dust may be removed from the exposed foam edge by the application of suction, alternatively or additionally the exposed foam edge is brushed to remove dust.

3. A method as claimed in any preceding claim wherein the seal is applied in line.

4. A method as claimed in any preceding claim wherein the seal comprises a gas and/or vapour barrier, the method may include the step of applying a seal in the form of a strip of film, membrane or tape to the exposed edge of the panel, the strip may be retained in place by adhesive bonding, the method may include the step of applying a seal forming liquid to the exposed edge of the panel, the liquid may be applied by spraying or by coating, the seal may comprise a polymeric material such as polyvinylidene chloride. polyvinyl alcohol or polyvinyl chloride, the seal may be a thermoplastic material, the seal may comprise a foil such as a metallic foil, the seal may comprise a laminate foil comprising polymeric material with a metallic coating. An insulating panel whenever manufactured by a method as claimed in any preceding claim.