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Title:
COMPOSITE XPS THERMAL INSULATION PANELS
Document Type and Number:
WIPO Patent Application WO/2012/016991
Kind Code:
A1
Abstract:
A composite XPS thermal insulation board may comprise a bottom, a central and a top XPS board having an extrusion skin at each external face of the composite XPS board with the individual XPS boards secured together to form the composite XPS board by thermal welds at their contact faces.

Inventors:
MUENDER KURT (DE)
FREEMAN MARK (FR)
GARCIA FELIX (ES)
Application Number:
PCT/EP2011/063319
Publication Date:
February 09, 2012
Filing Date:
August 02, 2011
Export Citation:
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Assignee:
KNAUF INSULATION (BE)
MUENDER KURT (DE)
FREEMAN MARK (FR)
GARCIA FELIX (ES)
International Classes:
B32B5/32; B29C65/20; E04B1/80
Domestic Patent References:
WO2011037740A12011-03-31
WO2011037740A12011-03-31
Foreign References:
EP1213119A22002-06-12
EP1213118A22002-06-12
DE4421016A11995-12-21
EP1318164A12003-06-11
GB1219516A1971-01-20
GB2184684A1987-07-01
JPH06218860A1994-08-09
DE4421016A11995-12-21
EP1213118A22002-06-12
EP1213119A22002-06-12
EP1231118A22002-08-14
EP1231119A22002-08-14
EP1318164A12003-06-11
GB1219516A1971-01-20
GB2184684A1987-07-01
JPH06218860A1994-08-09
Other References:
See also references of EP 2601044A1
Attorney, Agent or Firm:
ARC-IP SPRL et al. (Rue Emile Francqui 4, Mont-Saint-Guibert, BE)
Download PDF:
Claims:
Claims A composite XPS thermal insulation board comprising a bottom, a central and a top XPS board characterised in that each external face of the composite XPS board comprises an extrusion skin. A composite XPS thermal insulation board in accordance with claim 1 , in which the central XPS board comprises an extrusion skin on each of its contact faces. A composite XPS thermal insulation board in accordance with any preceding claim, in which the extrusion skin has been removed from the contact faces of the bottom and the top XPS boards. A composite XPS thermal insulation board in accordance with any preceding claim, in which the individual XPS boards are secured together to form the composite XPS board by thermal welds at their contact faces. A composite XPS thermal insulation board comprising a bottom, a central and a top XPS board, characterised in that each individual XPS board is secured to its adjacent XPS board(s) by a thermal weld at its contact face. A composite XPS thermal insulation board in accordance with claim 4 or claim 5, in which the thermal welds are variable intensity thermal welds. A composite XPS thermal insulation board comprising at least two individual XPS boards, characterised in that the individual XPS boards are secured together by a variable intensity thermal weld at their contact faces. A method of manufacturing a composite XPS thermal insulation board comprising laminating together a bottom, a central and a top XPS board characterised in that the method comprises the step of retaining the extrusion skin on each external face of the composite XPS board. A method of manufacturing a composite XPS thermal insulation board in accordance with claim 8, in which the method comprises the step of retaining the extrusion skin on each contact face of the central XPS board. A method of manufacturing a composite XPS thermal insulation board in accordance with claim 8 or claim 9, in which the method comprises the step of removing the extrusion skin from the contact faces of the bottom and the top XPS boards. A method of manufacturing a composite XPS thermal insulation board in accordance with any of claims 8 to 10, in which the method comprises the step of securing the individual XPS boards together by thermal welding at their contact faces. A method of manufacturing a composite XPS thermal insulation board comprising laminating together a bottom, a central and a top XPS board characterised in that the method comprises the step of securing the individual XPS boards together by thermal welding at their contact faces. A method of manufacturing a composite XPS thermal insulation board in accordance with claim 1 1 or claim 12, in which the step of thermal welding comprises creating variable intensity thermal welds at the contact faces of the individual XPS boards. A method of manufacturing a composite XPS thermal insulation board comprising laminating together at least two individual XPS boards, characterised in that the method comprises the step of securing the individual XPS boards together by a variable intensity thermal weld at their contact faces. A method of manufacturing a composite XPS thermal insulation board in accordance with claim 13 or claim 14, in which the variable intensity thermal welds are created in a step comprising passing contact surfaces of the individual XPS boards over a crenulated surface of a welding bar.
Description:
COMPOSITE XPS THERMAL INSULATION PANELS

This invention relates to extruded polystyrene (XPS) insulation panels.

XPS insulation panels are manufactured by extruding polystyrene with a blowing agent through a die or nozzle. The thermal conduction through an XPS insulating panel depends upon the panel's thickness and the panel's intrinsic properties (including, for example the cell structure created during extrusion and expansion and the insulating properties of the blowing agent used).

Unfortunately, the intrinsic insulating properties tend to degrade as the thickness of the extruded XPS insulating material is increased. Consequently, it can be advantageous to laminate two XPS boards together to form a thicker board such that the intrinsic insulating properties of the laminated insulating board are better than would be obtained by extruding a monolithic XPS board of the same thickness. Furthermore, previously used blowing agents are being replaced by blowing agents which are more environmentally friendly but whose ability to enhance the intrinsic insulating properties of XPS boards is generally reduced. Thus the use as blowing agents of, for example, HCFCs rather than CFCs, or CO2 rather than CFC or HCFCs exacerbates the difficulties of obtaining optimised intrinsic insulating properties with thick monolithic XPS boards. European patent application EP1 213 1 18 A1 discloses laminating together two XPS boards whose extrusion skin has been removed using a water permeable adhesive. The removal of the extrusion skin and the use of water permeable adhesive is intended to ensure that no barrier is created between the two boards which could block water vapour transmission. European patent application EP1 213 1 19 A1 discloses laminating together two XPS boards whose extrusion skin has been removed by solvent welding.

Again, the removal of the extrusion skin and the use of solvent welding is intended to ensure that no barrier is created between the two boards which could block water vapour transmission. A method of joining polystyrene and/or polyethylene boards using an oil heated bar to melt the contact surfaces is disclosed in DE4421016. However, EP1 213 1 18 A1 and EP1 213 1 19 A1 disclose that this method was not implemented as it produced a barrier layer between the two boards which prevents water vapour transmission.

Whilst EP 1 231 1 18 A1 and EP 1 231 1 19 A1 are primarily concerned with composite XPS boards which consist of two individual boards joined together, they disclose that a 60mm thick board can be used to make composite boards of 120 mm, 180 mm and 240 mm by joining respectively two, three or four 60 mm boards together. Similarly, it is disclosed that a 50 mm thick board can be used to make boards of 100 mm, 150 mm, 200 mm or 250 mm by joining respectively two, three, four or five 50 mm boards together.

The present invention provides a new and technically advantageous

configuration for a composite XPS board and associated manufacturing techniques.

In particular, in comparison with prior art monolithic XPS thermal insulation boards of the same thickness, the composite XPS thermal insulation boards of the present invention provide a means for:

- Reducing and/or improving the product density (increasing thickness of a monolithic XPS board generally increases its density); and/or

- Improving dimensional stability; and/or

- Reducing aging time (i.e. the time taken for cell gas content to stabilise).

According to a first aspect, the present invention provides a composite XPS board as defined in claim 1 . Other aspects of the invention are defined in other independent claims. The dependent claims define preferred or alternative embodiments.

The term "composite XPS board" indicates a board comprising a plurality of individual XPS boards which are secured together.

According to the teaching of EP1 213 1 18 A1 and EP1 213 1 19 A1 , it was considered essential to remove the extrusion skins from each face of the individual XPS boards when manufacturing a laminated, composite XPS thermal insulation board. It is thus surprising that a composite XPS thermal insulation board having acceptable properties, including acceptable water vapour transmission, can be configured without removing each extrusion skin. Retaining the extrusion skin at each external face of the composite XPS board may improve the water vapour transmission characteristics of the composite XPS product.

Thermal performance of a composite XPS board is a function of, inter alia, its overall thickness. Removal of extrusion skins, which is generally achieved by planing (typically using a rotary plane) removes a layer of material from the individual XPS board, thus reducing thickness. Consequently, when each extrusion skin of the individual XPS boards is removed in the manufacture of the composite XPS board, individual XPS boards must be manufactured so that they have a greater thickness before removal of the extrusion skin than their desired thickness after removal of the extrusion skin. The aspect of the present invention which provides for extrusion skin(s) to be retained not only reduces the number of steps in the manufacture of the composite XPS boards but also reduces the amount of raw material required to provide the individual XPS boards of the desired thickness. Retaining the extrusion skin on each contact face of a central XPS board has the additional advantage that this individual XPS board does not requires processing between its manufacture and its lamination to form the composite XPS board.

It may be advantageous to remove the extrusion skin from the contact face of bottom and top XPS boards, especially when a central XPS board comprises an extrusion skin on each of its contact faces, notably to optimise the thickness tolerance of the composite XPS board. When manufacturing an individual XPS board at a desired nominal thickness, the actual manufactured thickness will vary within a certain tolerance. In a composite XPS board, the variation in thickness will thus include the sum of the thickness tolerance of each individual XPS board. Removing the extrusion skin from the contact face of a bottom and a top XPS board, especially where the composite XPS board consists of three individual XPS boards, provides an advantageous way of controlling the tolerance of the thickness of the composite XPS board to be less than the sum of the extrusion thickness tolerances; this is because the thickness tolerance associated with removal of the extrusion skin may be controlled more easily and to a tighter degree than the extrusion tolerance. Thus, the tolerance of the thickness of the top and bottom XPS boards once their extrusion skins have been removed may be tighter than the tolerance of the thickness of the central XPS board. In some embodiments of the invention, the extrusion skin may be removed from each face of each XPS board.

In view of the teaching of EP1 213 1 18 A1 and EP1 213 1 19 A1 , it is also surprising that a composite XPS thermal insulation board having acceptable properties, including acceptable water vapour transmission, may be

manufactured by joining the individual XPS boards together by thermal welds. Variable intensity thermal welds provide an advantageous way of doing this, both in terms of the welding process and the manufactured composite XPS boards. The term "variable intensity thermal weld" designates a thermal weld in which the amount of melting or welding is more intense at some portions than at others. The variable intensity weld may comprise:

a) welded portions separated by less intensely or non-welded portions; and/or b) spaced welded portions in the form of lines separated by less intensely or non-welded portions.

Particularly where the composite XPS board consists of or comprises top, central and bottom XPS boards, the individual XPS boards are preferably welded together simultaneously to produce the composite XPS board.

The thermal weld may be created using a weld bar or bars passing over and preferably contacting and pressing against a surface to be welded. Preferably, the weld bar(s) are stationary with relative movement with respect to the surface to be welding resulting from movement of the XPS board(s). Embodiments in which weld bar(s) move may also be envisaged. The contact surface prior to welding may be substantially planar (for example in the state of a substantially flat XPS surface having its extrusion skin) or planar (for example an extruded surface having had its extrusion skin removed by rotary planing). Alternatively, the contact surface prior to welding may be profiled, for example, it may comprise a plurality of crenulations or peaks and trough, preferably regularly spaced across its surface. Such profiling may have (i) a pitch of greater than 10mm, or greater than 15 mm and/or less than

100mm, 80mm or 50 mm; and/or a peak to trough distance of greater than 0.5mm, or greater than 1 mm and/or less than 6mm or 5 mm. A profiled contact surface may be used (i) to create a variable intensity weld; and/or (ii) to optimise welding by melting primarily peaks of the profile to reduce the amount of material melted and/or increasing the area of the contact surface. Such a profiled surface may be provided by (i) extruding the surface with the desired profile; (ii) planing an extruded surface to remove the extrusion skin and provide the desired profile; or (iii) planing an extruded surface to partially remove the extrusion skin and provide the desired profile.

The invention is particularly advantageous in respect of composite XPS boards having a thickness of at least 90 mm, especially where each individual XPS board has a thickness of at least 20mm. Particularly where the composite XPS board consists of three individual XPS boards, its thickness may be less than 140 mm or less than 130 mm and/or greater than 210 mm or greater than 220 mm.

The thickness of individual XPS boards may be substantially the same; this facilitates the manufacturing process and manufacturing and stocking of the individual XPS boards as raw materials. Preferably, the thickness of the top and bottom XPS boards is substantially the same; the thickness of the bottom XPS board may be between ± 10% of the thickness of the top XPS board.

Particularly where it is desired to manufacture a composite XPS board having a thickness which can not be assembled from individual XPS boards having the same thickness, the thickness of the central XPS board may be different from the thickness of each of the top and bottom XPS boards by at least 5mm, preferably by at least 10mm. The composite XPS board is preferably free from adhesives. This facilitates recycling, both during manufacturing and at the end of the life of the product.

The invention will now be described, by way of example only, with reference to the accompanying drawings of which:

Fig 1 is a perspective view of a composite XPS thermal insulation board;

Fig 2 is an enlarged schematic representation of a variable intensity thermal weld;

Fig 3 is a schematic side view of apparatus suitable for manufacturing the XPS board of Fig 1 ;

Fig 4 is a side view of the welding bar shown in Fig 3;

Fig 5 is a schematic cross sectional view along line 5-5 of Fig 3;

Fig 6 is a schematic representation similar to Fig 5 of an alternative weld bar.

The composite XPS thermal insulation board 10 of Fig 1 comprises three individual XPS boards: bottom XPS board 1 1 , central XPS board 12 and top XPS board 13. It will be appreciated that the terms top, central and bottom are intended to indicate the relative positions of the individual XPS boards within the composite XPS board and not their orientation or the orientation of the composite XPS board.

Both the top external face 14 and the bottom external face 15 (hidden from view) of the composite XPS board comprise their XPS extrusion skins. The term "face" indicates the major surfaces of the composite XPS board or of the individual XPS boards as opposed to their two side surfaces and two end surfaces. The term "contact face" indicates a face at which an individual XPS board is in contact with another individual XPS board. In Fig 1 , only the edges of the contact faces are visible, the top 13 and central 12 XPS boards being secured together by thermal welding at their respective contact faces 13', 12' and the bottom 1 1 and central 12 XPS boards being secured together by thermal welding at their respective contact faces 1 1 ', 12".

The composite XPS board 10 has a thickness t, ie perpendicular to its external faces 14, 15 made up of the thicknesses of each individual XPS board 1 1 ,12, 13. Fig 2 shows an enlarged representation of part of the connection between contact faces of individual XPS boards. This shows a variable intensity thermal weld 21 comprising welded beads 22 separated by less intensely welded portions 23. Fig 3 illustrates a process of laminating bottom 1 1 , central 12 and top 13 XPS boards together to form composite XPS board 10. The individual XPS boards 1 1 , 12, 13 are advanced in direction 31 such that their contact faces pass over and are pressed against (by un-shown pinch rollers) heating surfaces

32,33,34,35 of thermal welding bars 36,37. Pinch rollers 38, 38' subsequently join the melted or partially melted contact faces of the individual XPS boards together to form the composite XPS boards 10. Drive rollers (not shown) situated upstream of the welding bars 36,37 push the individual XPS boards over the welding bars, some traction also being provided by the pinch rollers 38, 38'. The temperature of each weld bar 36,37 may be monitored, preferably at spaced positions across its length, and adjusted automatically to a desired nominal temperature. The weld bars 36, 37 are preferably electrically heated, though oil heating may be used. Whilst a single heat source may be used for the entire length of each weld bar, it is preferred to configure independently controllable heat sources for at least the extremities of each weld bar 36,37; this may facilitate obtaining a constant temperature along the entire length of each weld bar 36,37 taking in to account edge effects which are liable to disrupt the temperature at the extremities.

As shown in Fig 5 which is a cross section of weld bar 37 taken along line 5-5 in Fig 4, each heating surface 34, 35 of the weld bar comprises crenulations 51 which, in this embodiment, have the form of V-shaped teeth forming V-shaped peaks 52 and troughs 53. Alternatively, the crenulations may take the form of a series of square and/or rectangular shaped teeth. The crenulations 51 may be used to:

a) facilitate contact between the contact face of an individual XPS board and the weld bar, especially when the contact face is pressed against the weld bar by a roller (not shown) ; and/or

b) create a variable intensity thermal weld, the peaks of the crenulations causing more intense localised melting and/or welding of a contact face of an XPS board than the troughs.

In the configuration shown in Fig 5, the position of the peaks 52 on one heating surface 35 correspond to the position of the troughs 53 on the other heating surface 34. Figs 6 illustrates an alternative arrangement in which the position of the peaks 52 on one heating surface 35 correspond to the position of the peaks 52 on the other heating surface 34.

Preferably, the variable intensity thermal weld 21 comprises a weld of the entire (or substantially the entire) contact face of each XPS board having spaced weld portions 22 which are more intensely melted and/or welded. It has been found that this creates high mechanical strength at the join between individual XPS boards whilst also allowing acceptable levels of water vapour transmission for the composite XPS board.

XPS thermal insulation boards typically have a water vapour transmission of about 80-300. Example composite XPS thermal insulation boards in

accordance with the present invention have been found to have the following water vapour transmission:

Water vapour transmission properties are determined in accordance with EN 12086 and generally expressed as: - water vapour diffusion resistance factor, μ, for homogeneous products; and

- water vapour resistance, Z, for faced or non-homogeneous products.