METHOD AND APPARATUS FOR COATING INSULATION PANELS

Field of the Invention

[0001] The present invention relates to insulation panels, a method of coating insulation panels and an apparatus for coating insulation panels.

Background to the Invention

[0002] Insulation panels may be used in many insulation applications including in insulation of buildings and in other applications such as refrigeration units and the like. Insulation panels are thermally insulative, for example vacuum insulation panels or foam boards such as open or closed cell foams, for example phenolic, polyisocyanurate, polystyrene, or polyurethane foam insulation boards.

[0003] Insulation panels may lose their insulation performance over time. This may be due to the ingress of moisture and air. It may also be due to accidental damage to the insulation panel. It is known to coat insulation panels to minimise loss of insulation performance.

[0004] GB2548887 describes a method for coating a vacuum insulation panel comprising applying a liquid applied membrane by spraying and encapsulating a vacuum insulated panel with the liquid applied membrane wherein the method comprises spraying one side of the panel, turning the panel over, and spraying the other side of the panel.

[0005] Providing an alternative method of coating an insulation panel would be beneficial.

Summary of the Invention

[0006] In one aspect, the present invention relates to a method of coating an insulation panel comprising:

(i) positioning the insulation panel in a first coating position;

(ii) a first coating step comprising coating the insulation panel with a coating layer on a plurality of sides;

(iii) moving the insulation panel in at least one direction to a second coating position; and

(iv) a second coating step comprising coating the insulation panel with a coating layer on the remaining side(s), wherein the insulation panel is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete.

[0007] The insulation panel may be any suitable rigid insulation.

[0008] Positioning the insulation panel in a first coating position may be performed manually or in an automated manner, for example the insulation panel may be positioned on a processing line in a factory. In the first coating position the insulation panel is positioned in such a manner so that a plurality of sides are exposed to allow a plurality of sides to be coated.

[0009] The first coating step comprises coating the insulation panel with a coating layer on a plurality of sides may be performed manually or in an automated manner, for example the insulation panel may be coated on a processing line in a factory. The insulation panel is positioned in the first position so that a plurality of sides are exposed. Some or all of these sides may be coated while the panel is in the first coating position. The insulation panel is maintained in the same orientation during coating as it was orientated when positioned in the first coating position. The insulation panel is coated on a plurality of sides with a coating layer while it is positioned in the first coating position. The insulation panel does not move from the first coating position during the first coating step. At least some of the plurality of exposed sides are coated with the coating layer. Beneficially a plurality of sides being coated in the first coating step allows time and cost savings while coating the insulation panel as a number of sides can be coated at the same time before the insulation panel is moved.

[0010] Moving the insulation panel in at least one direction to a second coating position may be performed manually or in an automated manner, for example the insulation panel may be moved on a processing line in a factory. The insulation panel may be moved in one or more directions, for example horizontally, vertically, or a combination thereof, as long as the insulation panel is maintained in the same orientation as the insulation panel was oriented when positioned in the first coating position. For example, the insulation panel may move on a conveyor to the second coating position. Beneficially moving the insulation panel in at least one direction to a second coating position allows the sides which are not coated in the first coating position, for example because they are not exposed, to be then coated.

[0011] The second coating step comprises coating the insulation panel with a coating layer on the remaining side(s) may be performed manually or in an automated manner, for example the insulation panel may be coated on a processing line in a factory. The coating layer of the first coating step and the coating layer of the second coating step cure to form a continuous coating layer. Beneficially the second coating step completely envelopes the insulation panel in a continuous coating layer because it coats the remaining side(s) of the insulation panel. The coating layer may provide additional protection against damage to the insulation panel, for example accidental damage when handling the panel. The coating layer may provide additional benefits such as enhanced thermal insulation, enhanced vapour resistivity, or enhanced protection from moisture. The coating layer is coated to the entire exterior of the insulation panel and may provide the insulation panel with a waterproof barrier. The coating layer may be continuous over the entire surface of the envelope so that there are no discontinuities, such as voids or gaps in the coating layer. The coating layer may also reduce susceptibility of the insulation panel to damage, in storage, in transit, during installation and throughout the lifetime of the panel. This results in enhanced insulation properties and/ or increased longevity of the insulation panel.

[0012] The insulation panel is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete. The insulation panel is oriented in the same manner in the first coating position and the second coating position. The insulation panel is oriented in the same manner when moving in at least one direction from the first coating position to the second coating position. The insulation panel is not rotated or turned over between the first coating position and the second coating position. Moving the insulation panel from the first coating position to the second coating position does not alter the angle at which the insulation panel is orientated. The insulation panel only experiences planar movement. The insulation panel does not experience rotational movement. Beneficially maintaining the insulation panel in the same orientation from the beginning of the first coating step until the second coating step is complete may simply the coating process. Rotating the insulation panel can increase the expense of the coating process as it adds more complexity to the method so it is beneficial to maintain the same orientation of the insulation panel from the beginning of the first coating step until the second coating step is complete.

[0013] The method may comprise coating a second insulation panel, wherein the method comprises:

(i) positioning the second insulation panel in the first coating position;

(ii) a first coating step comprising coating the second insulation panel with a coating layer on a plurality of sides;

(iii) moving the second insulation panel in at least one direction to a third coating position while maintaining the first insulation panel in the second coating position; and (iv) a second coating step comprising coating the second insulation panel with a coating layer on the remaining side(s), wherein the second insulation panel is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete. Coating a second insulation panel while coating the first insulation panel may speed up the coating process for multiple insulation panels. The first coating position of the first insulation panel and the first coating position of the second insulation panel may be the same coating position. The second insulation panel is moved from the first coating position to a third coating position. The third coating position is a different position to the second coating position. Beneficially moving the second insulation panel in at least one direction to a third coating position while maintaining the first insulation panel in its second coating position may allow the coating layer on the first insulation panel to cure while coating the second insulation panel with a coating layer on the remaining side(s). This allows the process of coating more than one insulation panels to be faster. The coating layer on the first insulation panel can be cured while the coating layer is applied to the second insulation panel.

[0014] The at least one direction may be a vertical direction, for example it may be raising the panel. Beneficially this may increase the ease with which coating the insulation panel with a coating layer on the remaining side(s) is performed. The insulation panel may also be moved in lateral directions between the first and the second coating positions, for example, the insulation panel may be transferred along a conveyor. When coating a second insulation panel, moving the first insulation panel in a vertical direction may allow space for the second insulation panel to pass underneath the first insulation panel or moving the second panel in a vertical direction may allow space for the first insulation panel to pass under the second insulation panel.

[0015] A first side of the insulation panel may be positioned in contact with a supporting surface in the first position. Beneficially this may allow the insulation panel to support its own weight in the first position allowing the insulation panel to be self-supporting, for example, free-standing on the supporting surface without additional supports. Where the insulation panel is self-supporting it is possible to coat all the sides of the insulation panel apart from the first side while the insulation panel is in the first position.

[0016] Where the first side of the insulation panel is positioned in contact with a supporting surface in the first position, the method may comprise coating the insulation panel with a coating layer on one or more of the sides which are not contacting the surface for example all sides save the side that is in contact with the surface. Beneficially this allows all but one of the sides to be coated which may help reduce processing time. The insulation panel may be releasably held on one of the sides coated in the first coating step when the insulation panel is in the second coating position.

[0017] Where the first side of the insulation panel is positioned in contact with a supporting surface in the first position, moving of the insulation panel in the single linear direction will maintain the first side of the insulation panel parallel with the surface because the insulation panel is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete. The panel is not rotated, twisted, or turned in such a manner which would make the first side not remain parallel with the surface.

[0018] In a method of the invention coating may be performed by spraying. The first coating step and/or the second coating step may be performed by spraying. Beneficially spraying is a quick method for coating the insulation panel with the coating layer. Spraying may reduce wastage of the composition which forms the coating layer. Spraying may provide an even distribution of the coating layer so that the coating layer is of uniform thickness.

[0019] The method of the invention may comprise lowering the insulation panel after the second coating step. The insulation panel may be lowered onto one of the sides which was coated while the insulation panel was in the first position. Beneficially the coating layer on these sides may dry and/or cure while the insulation panel is in the second position so that there is no need to wait for the coating layer applied in the second position to dry and/or cure before lowering the insulation panel. While lowering the insulation panel it is no longer required for the insulation panel to maintain the same orientation. Once the second coating step is complete and the insulation panel is coated on all sides it is no longer essential to maintain the insulation panel in the same orientation.

[0020] The method of the invention may comprise delaying lowering the insulation panel after the second coating step until the coating is tack free as measured according to ASTM C679 - 15. Tack free means that the coating is dry and properly adhered to the outer surface of the insulation panel. When the coating is tack free it will be dry to the touch. When the coating is tack free is will not easily adhere to a surface onto which the insulation panel is placed. It will not wet the surface. Depending on the coating layer this may be from about 5 to about 60 seconds. For example a non-foam polyurethane coating layer may be tack free in about from about 5 to about 30 seconds, for example from about 10 to about 20 seconds. Beneficially delaying lowering the insulation panel provides time for the coating layer applied in the second position to dry or cure and become tack free. This allows the insulation panel to be lowered onto the side which is coated in the second coating step without the coating being damaged. [0021] In the method of the invention the insulation panel may be a vacuum insulation panel. The method is advantageous to use with vacuum insulation panels as vacuum insulation panels may benefit from being encapsulated in a coating layer, for example to provide protection from damage. Examples of suitable vacuum insulation panels are disclosed in GB2555099, the contents of which are incorporated herein.

[0022] The method may also be used on insulation panels such as foam boards, for example boards formed from phenolic foams, polyisocyanate foams, extruded polystyrene foams, or expanded polystyrene foams. Suitable insulation panels may be open celled or may be closed cell insulation foam boards.

[0023] The coating layer may be a polyurethane coating layer. The polyurethane coating layer may be formed from a polyurethane resin composition. The coating layer may be a non-foam polyurethane. The coating layer which is coated in the first position and the coating layer which is coated in the second position may be formed from different materials.

[0024] The coating layer may be a polyurethane resin composition comprising a first isocyanate containing part and a second polyol containing part. The polyurethane coating layer may be formed from a polyurethane resin composition. The polyurethane resin composition may be a two-part composition comprising a first isocyanate containing part and a second polyol containing part. The isocyanate containing part may have a viscosity of from about 2000 mPa s to about 3000 mPa s when measured at 20 °C. The polyol containing part may have a viscosity of from about 2000 mPa s to about 3000 mPa s when measured at 20 °C. Suitably, the isocyanate containing part and the polyol containing part each have a viscosity of 2000 to 2500 mPa s when measured at 20 °C, such as about 2300 mPa s when measured at 20 °C. This facilitates easy application of the resin to the VIP envelope. Beneficially the parts may be stored separately and mixed during the coating steps, for example they may be mixed by in a spray head when the coating is performed by spraying. Beneficially the polyurethane resin composition cures quickly.

[0025] The coating layer may be less than about 5 mm thick. Beneficially this thickness does not significantly increased the thickness of the insulation panel. The insulation panel which is coated in the coating layer is still suitable for applications, such as in refrigeration units, where space is at a premium and minimising the thickness is required. [0026] The coating layer may be from about 0.1 mm to about 3 mm thick, such as from about 0.1 mm to about 1.5 mm thick. Beneficially a thickness of about 0.1 mm means that the insulation layer will be sufficiently thick to provide the required benefit to the insulation panel. [0027] The coating layer may have a vapour resistance of from about 10 MN s/g to about 100 MN s/g, for example the polyurethane coating layer may have a vapour resistance of about 14 MN s/g or more for a coating thickness of about 0.5 mm to about 3 mm. Suitably, the coating layer may have a vapour resistance of 70 to 100 MN s/g, such as about 70 MN s/g or about 80 MN s/g or about 90 MN s/g, for a coating layer having a thickness of from about 0.5 mm to about 3 mm. Suitably the coating layer may be a polyurethane coating layer.

[0028] The coating layer may have a vapour resistivity of from 5000 MN s/gm to 100000 MN s/gm, preferably the coating layer has a vapour resistivity of about 7000 MN s/gm or more. For example the vapour resistivity may be about 6000 MN s/gm to 10000 MN s/gm, or about 10,000 MN s/gm to 100,000 MN s/gm, or about 20,000 MN s/gm to 90,000 MN s/gm, or about 30,000 MN s/gm to 80,000 MN s/gm or about 40,000 MN s/gm to 70,000 MN s/gm. Advantageously, the coating layer can act as a waterproof coating about the entire surface of the insulation panel. This reduces the insulation panel’s susceptibility to permeation from moisture, for example, rainwater in transit, or condensation when in storage or in use. The coating layer may also provide a barrier to corrosive substances such as corrosive acid, which may for example leach from other insulation panels such as foams in close proximity to the coated insulation panel.

[0029] In another aspect the present invention relates to an insulation panel coated according to the method of the invention. The insulation panel may be a vacuum insulation panel or a foam insulation board (with or without facing material applied), for example an isocyanurate foam board, a phenolic foam board, an extruded polyurethane foam board, an expanded polyurethane foam board, an extruded polystyrene foam board, or an expanded polystyrene foam board. The insulation panel may be formed from fibrous materials such as fibreglass or mineral wool.

[0030] In another aspect the invention relates to an apparatus for coating an insulation panel comprising:

(i) positioning means to position the insulation panel in a first coating position,

(ii) coating means for performing a first coating step coating wherein the insulation panel is coated with a coating layer on a plurality of sides of the insulation panel while the insulation panel is in a first position;

(iii) moving means for moving the insulation panel in at least one direction to a second coating position; and (iv) coating means for performing a second coating step comprising coating the insulation panel with a coating layer on the remaining side(s), wherein the insulation panel is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete.

[0031] The coating means for performing the first coating step and the coating means for performing the second coating step may be the same coating means. Beneficially this allows all the coating steps to be performed with a single coating means. All coating steps may be achieved with a single coating means. A single coating means may perform all the coating steps. The coating means may be on supporting means, such as a gantry, which allows the coating means to move from performing the first coating step while the panel is in the first coating position to performing the second coating step while the panel is in the second coating position.

[0032] The apparatus may comprise a second moving means for moving a second insulation panel in at least one direction from the first coating position to a third coating position while maintaining the first insulation panel in the second coating position. Beneficially this allows the coating applied to the first insulation panel in the second coating step to become tack free while the coating means is performing a second coating step on a second insulation panel.

[0033] The coating means may perform the second coating step on the first insulation panel in the second coating position and the same coating means may perform the second coating step on a second insulation in a third coating position. Beneficially this allows a single coating means to perform all the coating steps on both the first and the second insulation panel.

[0034] The moving means may move the insulation panel in a vertical direction. Beneficially this allows the side(s) of the insulation panel which were not coated in the first coating step to be coated. Wherein a second insulation panel is coated moving first insulation panel in a vertical direction allows the second insulation panel to travel beneath the first insulation panel to be positioned in the third coating position.

[0035] The coating means may be a spray means. Beneficially a spray means provides a quick method for coating the insulation panel with the coating layer. A spray means may reduce wastage of the composition which forms the coating layer. A spray means may provide an even distribution of the coating layer so that the coating layer is of uniform thickness.

[0036] The moving means may be releasably attachable to the insulation panel, for example the moving means may be a suction means. The moving means being releasably attached to the insulation panel allows the panel to be moved into the correct position and for the moving means to release the panel when it is no longer required to be attached to the panel.

Brief Description of the Drawings

[0037] Embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings in which:

[0038] Figure 1 is a flow diagram of an embodiment of the method of the invention.

[0039] Figure 2 is a flow diagram of an embodiment of the method of the invention.

[0040] Figure 3 shows an insulation panel which is coated in a coating layer.

[0041] Figure 4 shows an embodiment of an apparatus of the invention.

Detailed Description of the Drawings

[0042] An embodiment of the method 100 of coating an insulation panel 300 is shown in Figure 1. The method 100 comprises:

(i) positioning 102 the insulation panel 300 in a first coating position;

(ii) a first coating step 104 comprising coating the insulation panel 300 with a coating layer 302 on a plurality of sides;

(iii) moving 106 the insulation panel 300 in at least one direction to a second coating position; and

(iv) a second coating step 108 comprising coating the insulation panel with a coating layer 302 on the remaining side(s), wherein the insulation panel 300 is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete.

[0043] Figure 2 shows an embodiment of the method 200 of coating an insulation panel 300 where two insulation panels 300 are coated. The method 200 shown in Figure 2 comprises the steps shown in Figure 1 with the additional steps which may be performed to coat a second insulation panel 300.

[0044] The method 200 comprises:

(i) positioning 102 the insulation panel 300 in a first coating position;

(ii) a first coating step 104 comprising coating the insulation panel 300 with a coating layer 302 on a plurality of sides;

(iii) moving 106 the insulation panel 300 in at least one direction to a second coating position; positioning a second insulation panel 300 in the first coating position; (iv) positioning 202 a second insulation panel 300 in the first coating position;

(v) a first coating step 204 comprising coating the second insulation panel 300 with a coating layer 302 on a plurality of sides;

(vi) moving 206 the second insulation panel 300 in at least one direction to a third coating position while maintaining the first insulation panel 300 in the second coating position;

(vii) a second coating step 108 comprising coating the first insulation panel 300 with a coating layer 302 on the remaining side(s),

(viii) a second coating step 208 comprising coating the second insulation panel 300 with a coating layer 302 on the remaining side(s), and wherein the second insulation panel 300 is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete.

[0045] The second insulation panel 300 cannot be positioned 202 in the first coating position until the first insulation panel 300 has moved 104 from the first coating position. The first insulation panel 300 may be moving 104 from the first coating position to the second coating position while the second insulation panel 300 is being positioned in the first position. Alternatively the first insulation panel 300 may be positioned in the second coating position while the second insulation panel 300 is being positioned 202 in the first coating position.

[0046] The second insulation panel 300 may be moving 206 from the first coating position to the second coating position while the first insulation panel 300 is positioned in the second coating position. The second insulation panel 300 may be positioned in the third coating position before performing the second coating step 108 for the first insulation panel 300.

[0047] The second coating step 108 for the first insulation panel 300 may be completed before the second coating step 208 for the second insulation panel 300 is started.

[0048] The first insulation panel 300 may be lowered 110 while the second coating step 208 is ongoing or it may be beneficial to lower 110 the first insulation panel 300 after the second coating step 208 of the second insulation panel 300 is complete.

[0049] The second insulation panel 300 may be lowered 210 once the second coating step 208 is completed.

[0050] The at least one direction in which the insulation panel 300 is moved 106, 206 may be a vertical direction. Beneficially this allows the side(s) of the insulation panel 300 which are not coated during the first coating step 104, 204 to be coated with a coating later 302. Vertically moving 106, 206 the insulation panel 300 may also allow another insulation panel 300 to pass beneath the vertically moved insulation panel 300.

[0051] The first side of the insulation panel 300 may be positioned in contact with a supporting surface in the first spray position. When the insulation panel 300 is in this position the insulation panel 300 may be coated with a coating layer 302 on one or more of the sides which are not contacting the surface. The skilled person will appreciate that because the orientation of the insulation panel 300 is maintained from the beginning of the first coating step until the second coating step is complete when moving 106, 206 the insulation panel 300 in at least one direction the first side of the insulation panel 300 is maintained parallel with the surface.

[0052] The first coating step 104, 204 may be performed by spraying. The second coating step 108, 208 may be performed by spraying.

[0053] After the second coating step 108, 208 the method may comprise lowering 110, 210 the insulation panel 300. Lowering 110, 210 the insulation panel 300 may be delayed until the coating layer 302 is tack free as measured according to ASTM C679 - 15.

[0054] The coating layer 302 may be a polyurethane, for example non-foam polyurethane. The coating layer 302 may be a polyurethane resin composition comprising a first isocyanate containing part and a second polyol containing part. The coating layer 302 may be less than about 5 mm thick. The coating layer 302 may be from about 0.1 mm to about 3 mm thick, such as from about 0.1 mm to about 1.5 mm thick. The coating layer 302 may have a vapour resistance of from about 10 MN s/g to about 100 MN s/g. The coating layer 302 may have a vapour resistivity of from 5000 MN s/gm to 100000 MN s/gm, preferably the coating layer 302 may have a vapour resistivity of about 7000 MN s/gm or more.

[0055] An insulation panel 300 coated according to the method of the invention is shown in Figure 3. The insulation panel 300 which is coated according to the method of the invention will have a coating layer 302 on the outer surface of the insulation panel 300. The insulation panel 300 may be a vacuum insulation panel.

[0056] An embodiment of the apparatus 400 for coating an insulation panel is shown in Figure 4. The apparatus 400 is shown comprising:

(i) positioning means 402 to position the insulation panel 300 in a first coating position,

(ii) coating means 404 for performing a first coating step comprising coating the insulation panel 300 with a coating layer 302 on a plurality of sides; (iii) moving means 406 for moving the insulation panel 300 in at least one direction to a second coating position; and

(iv) coating means 408 for performing a second coating step comprising coating the insulation panel 300 with a coating layer 302 on the remaining side(s), wherein the insulation panel is maintained in the same orientation from the beginning of the first coating step until the second coating step is complete.

[0057] The positioning means 402 may be a means of raising the insulation panel 300 to a first coating position. When in the first coating position the coating means 404 can perform a first coating step comprising coating the insulation panel 300 with a coating layer 302 on a plurality of sides. The coating means 404 may be a spray means. The positioning means 402 may be a platform on which the insulation panel 300 can be positioned on. The positioning means 402 may be movable in a vertical direction to raise the insulation panel when the first coating position is a raised position.

[0058] Once the coating means 404 has coated a plurality of sides of the insulation panel 300 the insulation panel 300 may move from the first coating position to the moving means 406 for moving the insulation panel to the second coating position. For example, an insulation panel 300 may move around on a conveyor system 410, for example a chain conveyor or a belt conveyor. The apparatus, including the conveyor system 410, will maintain the insulation panel 300 in the same orientation throughout the movement from the first coating position to the moving means 406.

[0059] The moving means 406 will expose any uncoated sides of the insulation panel 300 so that the coating means 408 which is suitable for performing a second coating step will coat the insulation panel 300 with a coating layer 302 on the remaining side(s). The moving means 406 may be releasably attachable to the insulation panel 300, for example the moving means 406 may be a suction means. The moving means 406 will maintain the insulation panel 300 in the same orientation while the coating means 408 coats the insulation panel 300 with a coating layer 302 on the remaining side(s). The coating means 408 may be a spray means.

[0060] The moving means 406 will be suitable for moving the insulation panel 300 in at least one direction to a second coating position. The moving means 406 may, for example, be a suction means which can attach to a side of the insulation panel 300 on one of the plurality of sides of the insulation panel which is coated. The moving means 406 may move the insulation panel 300 in a vertical direction while maintaining the insulation panel 300 in the same orientation. [0061] The coating means for performing the first coating step 404 and the coating means for performing the second coating step 408 may be the same coating means. For example, a single coating means may move on a supporting means 412 from a position wherein the coating means can perform the first coating step to a position where the coating means can perform the second coating step. The supporting means 412 may be a frame or a gantry or the like.

[0062] The apparatus 400 may comprise a second moving means 414 for moving a second insulation panel 300 in at least one direction from the first coating position to a third coating position while maintaining the first insulation panel 300 in the second coating position. The second moving means 414 may be configured in the same manner as the first moving means 406. The moving means 414 may be releasably attachable to the insulation panel 300, for example the moving means 414 may be a suction means. Beneficially this allows the apparatus 400 to coat a second insulation panel 300 while the coating layer 302 on the first insulation panel 300 is curing or drying to become tack- free. Coating a second insulation panel 300 in the third coating position may be performed by a coating means 416. The coating means 416 may be a spray means.

[0063] The coating means which can perform the second coating step 408 on a first insulation panel 300 in the second coating position can be the same coating means 416 which can perform the second coating step on a second insulation 300 in a third coating position. The coating means may move from the second coating position to the third coating position and back again. The coating means may be on a supporting means 412, for example a frame or a gantry or the like.

[0064] A single coating means may be used instead of separate coating means for coating in the first, second, and third coating position.

[0065] The words “comprises/comprising” and the words “having/including” when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0066] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.