REINFORCED SEALING. TRIMMING OR GUIDING STRIPS

Field of the Invention

The present invention relates to reinforcing members formed from rigid material which in use are at least partially embedded in a strip formed of relatively flexible material. The strip may, for example, be for sealing around and supporting a window pane in the window for a vehicle door or for sealing between the door opening in the vehicle body and the door. The invention also relates to apparatus and methods for forming reinforcing members which in use are at least partially embedded in a strip formed of relatively flexible material

Background to the Invention

The use of sealing, trimming or guiding strips formed with flexible material is known for sealing around movable window panes mounted in door frames of vehicle doors and for sealing between the frame of a door and the door opening in the vehicle body. It is known to embed within the flexible material of such strips reinforcing members or "carriers". Typically, such reinforcing members or carriers are embedded within the part of the strip that forms a channel for gripping or receiving a flange of the door frame or vehicle body. The presence of the reinforcing member or carrier in the channel tends to securely locate the strip with respect to the flange or body.

It is also known to provide pre-formed loop-shaped sealing strips for fitment around closable openings of a vehicle such as around a door opening or a boot or trunk opening. The ends of the strips are joined together by a heat-bonding sheet of material. Such an arrangement is disclosed in WO-A-01 89810 ("Butt Joint"), which is hereby fully incorporated by reference. In that document the ends of the sealing strip to be joined and the heat-bondable sheet of material are

heated by a conventional heater so that the sheet of material thermally bonds to the extruded flexible material of the sealing strips. In the document the heat- bondable material has a melting point between 120 and 130 degrees C.

EP-A-0473283 ("SR carrier", GDX-6340) describes a strip that has a carrier embedded within the base and side walls of a flange-receiving channel of a strip formed of flexible material. The carrier has a plurality of slots formed therein which allow bending of the strip.

Typically, such a carrier is embedded within such the flexible material of the sealing, trimming or guiding strip by feeding the carrier into an extrusion die together with the flexible material. This forms the strip with the carrier embedded therein.

Such carriers are typically formed from metal. If the carrier is applied to the extrusion die with no surface treatment or coating, then it has been found that no bond (or only a very weak bond) is formed between the carrier and the flexible material. The flexible material and the carrier are generally coupled together by the flexible material passing through the slots, slits or apertures formed in the carrier so that parts of the flexible material positioned on opposite sides of the carrier are connected to each other by the flexible material that passes through the slots, slits or apertures. Such a coupling is not particularly strong. The flexible material may become detached from the carrier.

To overcome this problem it is known to coat the carrier with an agent. This agent causes the flexible material to bond to the carrier. The agent is applied to the carrier in liquid form prior to co-extrusion occurring with the flexible

material. These liquid agents are difficult and expensive to apply. For health and safety reasons, special precautions have to be made to ventilate the workspace where the bonding agent is applied to the carrier, which increases production costs.

In one aspect, embodiments of the present invention seek to provide an improved arrangement that allows a carrier to be bonded to the flexible material of a sealing, trimming or guiding strip.

Brief Summary of the Invention

According to a first aspect of the present invention, there is provided a reinforcing member formed of rigid material for being at least partially embedded in a strip formed of relatively flexible material, wherein the reinforcing member has a coating applied thereto which is bondable to the flexible material and to the reinforcing member such that the flexible material is secured to the reinforcing member, wherein the surface coating is formed from a material which is in a solid state with prior to application to the rigid member.

The material is in a solid state in the sense that it is not in a liquid or gaseous (fluid) state.

The reinforcing member may be a so-called "carrier". The carrier may be formed from any rigid material. Preferably, the carrier is formed from metal.

The material from which the surface coating is formed may be a powder. Alternatively, the surface coating may be in the form of a sheet, tape or foil.

In the embodiment heating means may be operable to heat the reinforcing member by exposing the member to an electrical or magnetic field. The heating means may comprise an inductive heater or a capacitive heater. The heating means may apply microwave radiation to the reinforcing member. These heating types each provide distinct advantages. The inclusion in a list should not be taken to imply that all the heating types are equivalent.

In some embodiments the heating means is operable to heat the reinforcing member to 120 ⁰ C or more.

According to a second aspect of the present invention, there is provided apparatus for forming a reinforcing member formed of rigid material for being at least partially embedded in a strip formed of relatively flexible material, including means for applying a coating to the reinforcing member which is bondable to the flexible material and to the reinforcing member such that the flexible material is secured to the reinforcing member, wherein the surface coating is formed from a material which is in a solid state with prior to application to the rigid member.

According to a third aspect of the present invention, there is provided a method of forming a reinforcing member formed of rigid material for being at least partially embedded in a strip formed of relatively flexible material, including applying a coating to the reinforcing member which is bondable to the flexible material and to the reinforcing member such that the flexible material is secured to the reinforcing member, wherein the surface coating is formed from a material which is in a solid state with prior to application to the rigid member.

Brief Description of the Drawings

For better understanding of the present invention embodiments will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a partial side elevational view of a motor car;

Figure 2 is a perspective view of the inner panel of a door for the motor car of Figure 1;

Figure 3 is a cross-sectional view taken along the line IV-IV of Figure 1 showing a sealing, trimming or guiding strip mounted on the door frame of the inner door panel of Figure 2;

Figure 4 shows a partial perspective view of the first carrier embedded within the sealing, trimming or guiding strip of Figure 3;

Figure 5 shows a partial perspective view of a second carrier for use in the strip of Figure 3;

Figure 6a and 6b show the partial overhead plan views of the carrier with special slot formations;

Figure 7 shows a perspective view of a carrier applied to a corner region of a frame;

Figure 8 shows a partial perspective view of a metal blank from which a carrier is formed;

Figure 9 shows a partial perspective view of the metal blank of Figure 8 to which a coating or film is applied in accordance with an embodiment of the invention;

Figures 10 to 15 show various embodiments of apparatus for forming a sealing, trimming or guiding strip having a carrier embedded therein in accordance with the invention;

Figure 16 shows a modification to the carrier coating to that shown in Figure 6a;

Figures 17a and 17b show forms of sheet for forming a carrier coating; and

Figures 18,19 and 20 show modifications of the Figure 13,14 and 15 embodiments in which the carrier coating is formed from powder.

In the drawings like elements are generally designated with the same reference numeral.

Detailed Description of Embodiments of the Invention

As shown in Figure 1, a car 5 has a door 6 and a window frame 8 defining an opening 10. The pane of window glass is slidable in a vertical direction in the frame 8 so as to be lowerable into a hollow part of the door 6.

In inner door panel 9 of the door 6 of Figure 1 is shown in more detail in Figure 2. The inner door panel 9 includes the frame 8. The finished door 6 will also have a outer panel fitted over and spot-moulded to (or attached by other means)

of the inner door panel 9. The outer panel will be visible from the exterior of the vehicle.

A sealing, trimming or guiding strip 11 is mounted to the frame 8 of the inner door panel 9.

Figure 3 shows in more detail the form of the frame 8 and the sealing, trimming or guiding strip 11. The window frame 8 is in the form of a metal section 12 which forms flange 18 and a channel 22 having a rigid re-entrant integral formation 23 extending partially across its mouth. The part of the sealing strip 11 along the top of the window 8 is shown as 24 in Figure 3. The sealing strip 11 defines a channel 28 which is sized to fit closely on the flange 18. The sealing strip 11 comprises a body formed of extruded, flexible, resiliently deformable plastics or rubber or similar material (e.g. TPE or EPDM).

The hook-shaped locking protrusion 30 of the strip 23 is resiliently deformed to fit into the channel 23 as the channel 28 is mounted on the flange 18. The protrusion 30 is provided with a hollow internal chamber 31. Integral coupling parts 33A and 33B are provided on opposite sides of the protrusion 30. Coupling part 33 A engages the rigid re-entrant formation 23. Coupling part 33B engages rigid protrusion 35 formed on the flange 18. In this way, the strip 24 is secured to the frame 8 and this is assisted by the first rigid carrier 36 which is embedded in the extruded material of the strip. The carrier 36 reinforces the sealing strip 11 in the region of the channel 28.

The carrier 36 may be of any suitable form. It may be made of unapertured metal strip. Instead, however, it may incorporate slits or slots (e.g. to increase its flexibility) or could be in the form of (completely) separate side-by-side

metal elements. In another form, it could be made of looped wire. The base of the channel-shape formed by the carrier 36 may be unapertured and or the channel-shape formed by the carrier 36 may be provided with parallel slits at the base. Different forms of carrier 36 will be described later.

The extruded plastics or other material of the strip 11 extends to form sealing lips 38, which extend from the opposite side of the channel 28 to the formation 30. The sealing lips 38, when the door 6 is closed, seal against the part of the car 5 body which runs along the top of the door opening. On the same side as the channel 28 as the formation 30 (on the outside of the car 5 body), extruded material extends to form a lip 42 which is one wall of a glass-receiving channel 44 for receiving the window glass 46. The glass-receiving channel 44 has a base lip 48 extending across the base of the channel 44 abutting against the end of the window glass 46. The second wall of the channel 44 is formed by a linear limb 49 from which two further sealing lips 50 extend. The lips 50 engage one side of the glass - the opposite side of the glass that is engaged by the sealing lip 42. The sealing lips 42, 48 and 50 may be provided with a flocked surface or other low-friction surface treatment 52.

Along the side of the window frame 8 a further carrier 54 may be embedded within the lip 42 in order to reinforce that lip. The further carrier 54 may be in the form of a thin, generally linear metal strip. The further carrier 54 may be provided with slits 56 as shown in Figure 4. These slits 56 better enable the further carrier 54 to be bent as necessary to follow curves in the window frame 8.

The first carrier 36 is generally U-shaped (or channel-shaped) and may have an integral limb 60 extending from one end thereof which extends generally

parallel to the limb 49 of the channel 44 of the strip 11, so that the channel 44 lies to one side of the limb 60 and the protrusion 30 extends to the opposite side of the limb 60.

The first carrier 36 can be formed from a metal blank 62 of the form shown in Figure 5. The metal blank 62 has a plurality of slits 64 formed therein. The slits 64 may be expanded to form slots by stretching the blank 62 in a longitudinal direction of the blank in order to enlarge the slits 64 to form the slots.

Alternative forms of carrier are shown in Figures 6a and 6b. The carrier of Figure 6a includes a region A of less flexible, i.e. a more rigid, material which is undisturbed (solid) material. The carrier also includes a second more flexible, i.e. less rigid, and more compressible, region B having generally linear slots 66 which extend transversely inwardly from its edges, as well as both transversely and longitudinally intermediately disposed arcuate slots 68. If desired, the more flexible region B may be stretched to expand longitudinal to increase the widths of the slots 66 and arcuate slots 68 to further increase flexibility and compressibility. The arcuate slots 68 may have a linear wall 69 and an arcuate wall 70 opposite thereto, such that the middle of the slots 68 is wider than the edges of the slots.

Figures 6b shows a different arrangement of carrier. This carrier also includes a region A of less flexibility and less compressibility, which is defined by a plurality of generally circular through-apertures 74. The through apertures 74 are preferably aligned in uniform columns and rows and occupy a central portion of the carrier but not the longitudinal outer, edge-adjacent regions. The carrier also includes a region B of increased flexibility and increased

compressibility, comprising a plurality of slots 66 and a plurality of slots 68 having the same form as the correspondingly numbered slots of Figure 6a.

Figure 7 shows an alternative arrangement of carrier. The carrier of Figure 7 corresponds to the carrier shown in Figure 5 but bent to form a U-shaped channel which is configured to extend around a flange (for example, a flange like 18 as shown in Figure 3 or a flange formed around a boot or trunk opening of a car body). The flange 76 extends around an approximately right-angled corner 80. The carrier is able to follow the contour of the corner 80 by virtue of the slits formed either side of the base 82 of the carrier. The legs 84 of the carrier are able to be splayed apart in the region of the corner 80.

As explained above, typically the carrier would be formed from an unapertured metal blank formed for example aluminium or steel. Such a plain metal blank for forming the carrier 85 is shown in Figure 8. As also mentioned above, a problem exists with known carrier arrangements which are embedded in flexible sealing strips, in that there is no direct bonding between the metal of the carrier and the flexible material. A known liquid agent or primer can be applied to the carrier 85 in order to enable the carrier to be fixed to the flexible material but this is difficult and expensive to apply.

Figure 9 shows a sheet of material or foil 100 applied to a first surface of the carrier 85 to form a coating 101. A similar sheet of material or foil 102 may be applied to the second, opposite surface of the carrier 85 to form a coating 103. It is not essential that a coating 101,103 is applied to both sides of the carrier - a coating 101,103 may be applied to only one side. Additionally, or alternatively, a coating may be applied to the ends 87 or sides 89 of the carrier 85. The sheets 100, 102 are formed of a material which readily bonds to the

carrier 85, and also readily bonds to the flexible material of the strip 11. The coating 101,103, therefore, allows the material of the carrier 85 to be fixed/bonded firmly to the material of the strip 11 by means of the intermediate coating 101,103. The coating 101,103 is straightforward to apply by attaching the sheets 100,102 to the carrier 85, compared to the known liquid coatings.

The sheets 100,102 may comprise thermoplastic material, polyolefin or (e.g. long chain) polyethylene. In the embodiment, the sheets 100,102 may be of any suitable type for ensuring an effective bond between the flexible material of the strip 11 (e.g. EPDM) and the carrier 85 (i.e. the sheet 100,102 will bond to both the flexible material of the strip 11 and the carrier 85, thereby securing them together), taking into account the material and characteristics of the flexible material from which the body of the sealing strip 11 is formed and the material from which the carrier 85 is formed. The sheets 100,102 may, for example, have a melting point of between 120 and 130°C.

The sheets 100,102 are generally flat/planar (and may be stored and supplied from a reel around which they are wound).

As shown in Figure 9 the sheet 100 may include a plurality of slits or apertures 104 formed therein. These allow the passage of air between the carrier 85 and the coating 101 - making the coating 101 air-permeable. The slits or apertures 104 may prevent air bubbles appearing between the carrier 85 and the coating 100, so that the coating 100 may be applied smoothly and closely over the carrier 85. It should be understood that the slits or apertures 104 may not be present in the sheet 101/coating 100.

The present invention is applicable to many forms of carrier. The carrier may be formed of solid material, as shown in Figure 8. The carrier may alternatively have slots, slits or apertures formed therein as shown in Figures 4, 5, 6a, 6b or 7.

Figure 9 shows the coatings 101, 103 formed over (lie entire width of the carrier 85. A coating may be formed over only part of the width of the carrier 85. Figure 6a shows the coating 101 formed only over the central region of the carrier 85. That is, the coating 101 does not extend to the edges of the carrier 85. The coating is confined between the dashed lines 106.

In Figure 6b the coating 101 is provided only along the edges of the carrier. That is, the coating 101 is not present in the central region at all - i.e. the coating 101 is not present in the region containing the slots 68 and the apertures 74. The region between the inner dashed lines 108 of Figure 6b is not provided with a coating 101. Also, the region outward of the outer dashed lines 109 is not provided with a coating 101.

Referring now to Figure 7, the coating 101 is applied only over the unapertured base portion 82 of the carrier.

Various arrangements for forming a sealing or guiding strip 11, comprising a coated carrier 85 will now be described with reference to Figures 10 to 15.

Figure 10 shows reel 110 around which a carrier 85 bank is wound - that is a metal carrier in an unapertured state, as shown in Figure 8. The sheet 100 is applied to the carrier 85 at processing station 112. The sheet 100 is applied to the carrier 85 by heating the sheet 100 and/or the carrier 85 so that the sheet

100 bonds to the carrier 85 to form coating 101. The coated carrier then passes to processing station 114 comprising a plurality of movable rollers 115. The processing station 114, by means the positioning of rollers 115 as shown, stores a length of the coated carrier 85. Storing a length of coated carrier 85 in this way may be advantageous when it is desired to change the reel 110 containing the carrier 85 bank - for example, when the carrier reel 110 is exhausted (i.e. all the carrier material has been used). When this happens, the stored carrier material in the processing station 114 can continue to be supplied to the subsequent processing unit 116 whilst an operator connects a new reel 110 of carrier material. The new reel 110 can be connected to the processing station 112, so that the coating 100 can be applied as before. The carrier material is then applied to the processing station 114. By moving the rollers 115 in order to allow different lengths of carrier material to be stored in the processing station 114, a continuous supply of carrier can be provided to the processing unit 116 despite there being an interruption in the supply of carrier to the processing station 114.

In addition to storing carrier material, the processing station 114 may also cool the carrier 85 and coating 101 (which was heated in order to allow the sheet 100 to adhere to the carrier 85). This may be performed by blowing relatively cool air onto the coated carrier 85, or by any other means. Cooling may be performed prior to the processing station 114.

At the processing unit 116 slits, apertures or slots are formed in the carrier 85. These slits, apertures or slots may be of the form as described earlier (reference numbers 64,66,68,74), or any other suitable form. The processing unit 116 may further stretch the carrier 85 in a longitudinal direction to open the slits.

The processing unit 116 may also shape the carrier 85, for example, into a U- shape (or channel-shape).

It is advantageous to cool the coated carrier 85 (in the processing stage 114 or elsewhere) because otherwise the hot coating 101 might stick to the cutting parts of the processing unit 116.

Figure 11 shows an alternative arrangement. In this arrangement the coating stage 112 is located after, i.e. downstream of, the storage stage 114 and the aperture forming stage 116. A separate shaping stage 118 is provided downstream of the coating stage 112. This stage 118 shapes the carrier into a desired shape - for example a U-shape. Advantageously, the coated carrier may be cooled at an intermediate stage between the coating stage 112 and the shaping stage 118 - for example by applying relatively cool air.

Figure 12 shows a further processing arrangement for the carrier 85. In Figure 12 the reel 110 is present, but is not shown. Carrier 85 material from the reel 110 is passed to aperture forming stage 116, and from there to carrier shaping stage 118. Downstream of the aperture forming stage 116 is the coating applying stage 112.

Figure 12 additionally shows an extrusion head 120. The extrusion head 120 receives the coated carrier 85 and also the flexible material (not shown) from which the sealing, trimming or guiding strip 11 is formed. In the extrusion head 120 the flexible material is bonded to the coated carrier 85. The sealing strip 11 that exits from the extrusion head 120 may have the form of the sealing strip shown in Figure 3, with the carrier(s) embedded therein. Of course, if two

carriers are present (as shown in Figure 3 at 36 and 54), two carriers will be supplied to the extrusion head.

No extrusion head 120 is shown in Figures 10 or 11. However, for those arrangements, when it is desired to embed the coated carrier 85 within flexible material to form a sealing, trimming of guiding strip, the coated carrier 85 will be supplied to an extrusion head 120.

In the Figure 12 arrangement, the carrier 85 and sheet 100 (not shown) which forms the carrier 85 coating 101 is heated to above the melting temperature of the sheet 100 at coating stage 112. The heated coated carrier 85 is then applied to the extrusion head 120. This will cause the coating 101 to firmly bond to the carrier and also will cause the coating 101 to firmly bond to the flexible material from which the sealing strip 11 is formed. Thus, the carrier is fixed in position relative to the sealing strip by the coating 101. The nature of the heating will be discussed further below

Figure 13 shows an alternative embodiment. In contrast to Figure 12, no separate coating stage 112 is provided. Instead, the sheets 100,102 for forming the coatings 101,103 are supplied from reels 122 directly into the extrusion head 120. Conventionally, the material passing through an extrusion head 120 (which in this instance will comprise the carrier 85, sheets 100,102 and flexible material forming the strip 11) will be heated to approximately 9O ⁰ C. This is below the melting temperature of the sheet 100,102. This may cause the sheet 100,102 to bond only to the flexible material, and not to the metal carrier 85. In order to facilitate the bonding of the coating material to the carrier 85 (in addition to the flexible material), a heating stage 124 may be provided between the shaping stage 118 and the extrusion head 120 - to heat the carrier 85.

The heating stage 124 may be applied by any conventional (e.g. primarily convection) mechanism, such as by a flame, oven, hot air blower or other heat source as shown. The carrier 85 may be heated as it travels between the shaping stage 118 and the extrusion head 120 at a temperature of substantially 300 ⁰ C, for example. The heating stage 124 heats the carrier 85 primarily by convection. The high temperature of the heating stage 124 heats the carrier sufficiently so that the sheet 100,102 bonds to the carrier 85 when it comes into contact with the carrier in the extrusion head. The flexible material then readily bonds to the sheets 100,102. The strip 11 is therefore formed with the carrier 85 firmly connected to the flexible material - by means of sheets 100,102.

Alternatively, the carrier 85 may be heated by at least one of inductive heating, capacitive heating, the application of an electric field, the application of a magnetic field and the application of a microwave radiation. Thus, heating may be achieved without conventional convection heating.

In order to bond the carrier 85 to the sheet 100,102 the carrier is heated to approximately 120°C or more. The temperature may be approximately 18O ⁰ C or 300 ⁰ C, for example. (WO-A-0189810 - discussed above - discloses a foil that has a melting point of between 120 and 130 ⁰ C. The temperature to which the carrier is heated is not stated, and will be less than 120 ⁰ C - typically 80 ⁰ C.)

In the alternative arrangement, the carrier 85 is exposed to electromagnetic radiation (for example microwave radiation), or to a magnetic or electrical field to cause inductive or capacitive heating of the carrier 85. For example, the radiation may be applied at a power of 900 watts. Applying such radiation or a magnetic or electrical field causes heating of the carrier 85. Simultaneously or

contemporaneously heat may be applied to the flexible material and sheet 100,102 using, for example, the heating stage 124 described above.

The radiation applying means may be incorporated in the heating stage 124. Alternatively, the flexible material and sheets 100,102 may be heated by the extrusion head 120.

Further alternatively, the metal carrier 85 may heat the flexible material and sheets 100,102 when they lie adjacent to the carrier 85 (by virtue of the heat already applied to and stored in the carrier 85). However, it may be preferable (but is not essential) that conventional heat is applied in addition to the microwave radiation or a magnetic or electrical field because the microwave radiation (or the magnetic or electrical field) will only directly heat the carrier 85. The inductively/capacitively heated carrier 85 will in turn heat the flexible material of the strip 11 (by conduction) close to the carrier 85 but may not heat sufficiently parts more distant from the carrier 85. By applying conventional heat in addition to the electromagnetic radiation, or a magnetic or electrical field, the whole of the flexible material of the strip 11 can be brought to the required temperature.

If the carrier 85 is formed of a material that can be heated by inductive or capacitive heating. A suitable metal may be used - for example steel. Carbon/graphite may be added to the carrier 85 to facilitate inductive or capacitive heating.

Figure 13 shows reels 122 which supply the sheets 100,102 to the extrusion head 120. These reels 122 may not be provided. Instead, the carrier 85 coating may be provided from a source directly to the extrusion head 120. The

extrusion head 120 is then modified to include an additional die to form the coating on the carrier by extrusion.

Figure 14 shows a modification to the Figure 13 arrangement. In this arrangement, additionally heaters 126 are provided for heating the sheets

100,102. Further, rollers 128 are provided which press the sheets 100,102 against opposite sides of the carrier 85 in order to firmly bond the sheet

100,102 to the carrier 85 to form coating 101,103. Preferably, the rollers 128 are coated with PTFE in order to prevent the coatings 101,103 adhering to the roller 128.

Figure 15 shows yet a further embodiment. In this embodiment additional rollers 130 are provided in pressing stage 132 to press the sheets 100,103 against the carrier 85. Incorporated within the pressing stage 132 may the of inductive/capacitive heater for heating the carrier 85.

The rollers 128 may be arranged to move transversely with respect to the direction of travel X of the carrier 85 (that is, perpendicularly to the plane of the paper of the Figure). This allows the position of the coating 101,103 on the surface of the carrier 85 to be varied. For example, the coating may be present at varying positions on the carrier along the length of the carrier. For example, along one length of the carrier, the coating 101 may be positioned as shown in Figure 6a whereas, by moving the rollers 128 transversely, along another length of the carrier the coating 100 can be extended up to one edge of the carrier (and will be consequently be further from the other edge of the carrier) - as shown in Figure 16.

By appropriate selection of the carrier slits, slots or apertures, and/or appropriate selection of the size and position of the coating 101,103, the position of the neutral bending axis of the strip 11 can be predetermined: the neutral bending axis is the line along which, when the strip 11 is bent, the flexible material is subjected neither to compressive nor to tensile forces.

In a modification, two or more heat sources are provided which heat the sheet 100,102. For example, a first heat source may be provided at position Hl or H2 in Figure 15, and a second heat source may be provided at position H3. The first heat source may heat the sheet 100,102 to approximately 100 degrees C (when the heat source is in position Hl, this heating will be applied indirectly by the carrier 85 heated by the heat source). Heating by the first heat source will enable weak bonding between the sheet 100,102 and the carrier 85. The second heat source subsequently may heat the carrier 85/sheet 100,102 to approximately 180 degrees C. The first and second heat sources may be spaced apart by 30 cm for example. The provision of a first, relatively cool heat source may allow initial weak bonding of the partially melted sheet 100,102 to the carrier 85 before the higher temperature heating is applied. This may reduce the likelihood of the sheet 100,102 melting prior to application to the carrier 85.

The sheets 100,102 may be melted before they are applied to the carrier 85. The material from the sheets 100,102 may be applied to the carrier 85 in liquid form.

Figure 17a shows a cross section through the sheet 100 according to one embodiment of the invention. In this embodiment the sheet has a constant cross section.

Figure 17b shows an alternative embodiment. In this embodiment the sheet 100 has two domed portions 134 positioned just inwardly of the edges of the sheet 100. The excess material in the domed regions 134 may be pressed into the slits, slots or apertures in the carrier by the rollers 128 (or rollers 130). This may advantageously reduce the rippled appearance in the exterior surface in the sealing strip (where indentations appear at regions corresponding to the slits, slots or apertures) in the carrier. This is also known as the "hungry dog" effect.

The inductive/capactive heating may be performed by positioning the carrier 85 within a coil in order to inductively heat the carrier 85. A source of high frequency electricity is used to drive a large alternating current through the coil. Such a coil is known as the work coil. The passage of current through the coil generates a very intense and rapidly changing magnetic field in the space within the work coil. The alternating magnetic field induces a current flow in the conductive carrier 85. The arrangement of the work coil and the carrier 85 can be thought of as an electrical transformer. The work coil is like the primary where electrical energy is fed in, and the carrier 85 is like a single turn secondary that is short-circuited. This causes large eddy currents to flow through the carrier 85.

In addition to this, the high frequency used in induction heating applications may give rise to a phenomenon called skin effect. This skin effect forces the alternating current to flow in a thin layer towards the surface of the carrier 21. The skin effect increases the effective resistance of the metal to the passage of the large current. Therefore it greatly increases the heating effect caused by the current induced in the carrier 85.

For ferrous metals like iron and some types of steel, there is an additional heating mechanism that takes place at the same time as the eddy currents mentioned above. The intense alternating magnetic field inside the work coil repeatedly magnetises and de-magnetises the iron crystals. This rapid flipping of the magnetic domains causes considerable friction and heating inside the material of the carrier 85. Heating due to this mechanism is known as

Hysteresis loss. This can be a large contributing factor to the heat generated during induction heating, but only takes place inside ferrous materials. For this reason ferrous materials lend themselves more easily to heating by induction than non-ferrous materials .

The sheet 100,102 may be adapted to be heatable by a capacitive and/or inductive heating. For example, the sheet 100,102 be electroconductive and may comprise carbon/graphite or the like. This renders the sheet 100,102 heatable by inductive/capacitive heating.

The sheet 100,102 may be formed from material available from Collano Ziro AG. The Collano Xiro material may have the following chemical characterisation: Thermoplastic hotmelt adhesive film based on modified polyethylene copolymers (ethylene vinyl acetate, EVA) with small amounts of additives (e.g. chalk, talcum and/or waxes). It can be delivered as a coating, a slit or unslit film with or without PE or siliconized paper as carrier.

The Collano film may be type XAF 2210/2211 previously available from Sarna Xiro AG. It has the following properties :-

Chemical Basis thermoplastic adhesive film based on modified Polyolefin

Melting temperature 120 - 130 ⁰ C (Kofler Bank)

Melt Flow Index (190°C/21.2N) 2-6 g/10min (DIN 53735)

Density 0.92 g/cm ³ (DIN 53479)

Minimum bonding temperature 140 ⁰ C

As an alternative to the coating being formed from sheets 100, 102, the material from which the surface coating is formed may be a powder (in pellet form). The powder may include polyethylene or polyolefϊn. The powder may be applied at a rate of 1 gram per metre at a width of 45mm. The powder may be applied over the same area as the sheet 100,102 in the embodiments described above, and as shown by the dashed lines 106 in Figure 6a, 108 and 109 in Figure 6b, Figure 7, and 106 in Figure 16.

The Collano film may be formed into a powder by breaking up the film into particles prior to application to the carrier.

As an alternative, the powder coating may be formed from material known as DuPontNucrel ® 0910HS.

DuPont Nucrel 091 OHS (high stability) is a copolymer of ethylene and methacrylic acid made with nominally 8.7 wt% methacrylic acid. It contains one of more of the following ethylene copolymers:-

CAS Number %

9010-77-9 0-100

25053-53-6 0-100

37433-35-5 0-100

It has a melting point of 80-105 ⁰ C. It can be used in extrusion coating, co- extrusion and laminating processes. It is available in pellet form. It has the following properties :-

Physical Nominal Values Test Method

Density 0.93g/cm ³ ASTM D792 - ISO 1183

Melt Index (190°C/2.16kg) lOg/10 min ASTM D1238 - ISO 1133

Thermal Nominal Values Test Method Melting Point (DSC) 103 ⁰ C (217°F) ASTM D3418 - ISO 3146

Vicat Softening Point 86°C (187 ⁰ F) ASTM D1525 - ISO 306

Freezing Point (DSC) 84 ⁰ C (183°F) ASTM D3418

Nucrel 091 OHS is normally processed at melt temperatures ranging from 260°- 305 ⁰ C in flat die equipment. The actual processing temperatures will usually be determined by either the specific equipment or substrate or one of the other polymers in a co-extrusion. Materials of construction used in the processing of this resin should be corrosion resistant. Stainless steels and/or duplex chrome or nickel plating are recommended for dies and adapters.

For extrusion processing the following temperatures are suggested: -

Cylinder Zone 5 Temp. 290 ⁰ C

Cylinder Zone 4 Temp. 290 ⁰ C Cylinder Zone 3 Temp. 280 ⁰ C

Cylinder Zone 2 Temp. 23O ⁰ C

Feed Zone 235 ⁰ C

Melt Temperature 290 ⁰ C

Die Zone 290°C

When a powder coating is applied, the Figure 10 embodiment is modified to apply the powder to the carrier 85 at processing station 112. The powder may be applied to the carrier from a reservoir by air pressure. The powder is applied to the carrier 85 by heating the powder and/or the carrier 85 so that the powder bonds to the carrier 85 to form a coating. The coated carrier then passes to processing station 114 as in the Figure 10 embodiment using sheet 100.

In addition to storing carrier material, the processing station 114 may also cool the carrier 85 and coating (which was heated in order to allow the powder to adhere to the carrier 85). This may be performed by blowing relatively cool air onto the coated carrier 85, or by any other means. Cooling may be performed prior to the processing station 114.

At the processing unit 116 slits, apertures or slots are formed in the carrier 85 as in the Figure 10 embodiment using sheet 100.

When a powder coating is applied, the Figure 11 embodiment is modified to apply powder by the coating stage 112 located after, i.e. downstream of, the storage stage 114 and the aperture forming stage 116.

When a powder coating is applied, the Figure 12 embodiment is modified to apply powder by the coating applying stage 112. In the Figure 12 arrangement, the carrier 85 and powder which forms the carrier 85 coating is heated to above the melting temperature of the powder at coating stage 112. The heated coated carrier 85 is then applied to the extrusion head 120. This will cause the coating to firmly bond to the carrier and also will cause the

coating 101 to firmly bond to the flexible material from which the sealing strip 11 is formed. Thus, the carrier is fixed in position relative to the sealing strip by the coating.

5 Figure 18 shows an alternative embodiment, with similarities to the Figure 13 embodiment. In contrast to Figure 12, no separate coating stage 112 is provided. Instead, the powder 150 for forming the coating is supplied from reservoir 154 directly into the extrusion head 120 via guide 156. Conventionally, the material passing through an extrusion head 120 (which in

10 this instance will comprise the carrier 85, powder 150 and flexible material forming the strip 11) will be heated to approximately 90°C. This is below the melting temperature of the powder 150. This may cause the powder 150 to bond only to the flexible material, and not to the metal carrier 85. In order to facilitate the bonding of the powder coating material to the carrier 85 (in

1.5 addition to the flexible material), a heating stage 124 may be provided between the shaping stage 118 and the extrusion head 120 - to heat the carrier 85.

The heating stage 124 may be applied by any conventional (e.g. primarily convection) mechanism, such as by a flame, oven, hot air blower or other heat 0 source as shown. The carrier 85 may be heated as it travels between the shaping stage 118 and the extrusion head 120 at a temperature of substantially 300 ⁰ C. for example. The heating stage 124 heats the carrier 85 primarily by convection. The high temperature of the heating stage 124 heats the carrier sufficiently so that the powder 150 bonds to the carrier 85 when it comes into

25 contact with the carrier in the extrusion head 120. The flexible material then readily bonds to the powder 150. The strip 11 is therefore formed with the carrier 85 firmly connected to the flexible material - by means of powder coating.

Alternatively, the carrier 85 may be heated by at least one of inductive heating, capacitive heating, the application of an electric field, the application of a magnetic field and the application of a microwave radiation. Thus, heating may be achieved without conventional convection heating.

In order to bond the powder to the carrier 85 the carrier is heated to approximately 120 ⁰ C or more. The temperature may be approximately 180 ⁰ C or 300 ⁰ C, for example.

In the alternative arrangement, the carrier 85 is exposed to electromagnetic radiation (for example microwave radiation), or to a magnetic or electrical field to cause inductive or capacitive heating of the carrier 85. For example, the radiation may be applied at a power of 900 watts. Applying such radiation or a magnetic or electrical field causes heating of the carrier. Simultaneously or contemporaneously heat may be applied to the flexible material and powder 150 using, for example, the heating stage 124 described above.

The radiation applying means may be incorporated in the heating stage 124. Alternatively, the flexible material and powder 150 may be heated by the extrusion head 120.

Further alternatively, the metal carrier 85 may heat the flexible material and powder 150 when they lie adjacent to the carrier 85 (by virtue of the heat already applied to and stored in the carrier 85). However, it may be preferable (but is not essential) that conventional heat is applied in addition to the microwave radiation or a magnetic or electrical field because the microwave radiation (or the magnetic or electrical field) will only directly heat the carrier

85. The inductively/capacitively heated carrier 85 will in turn heat the flexible material of the strip 11 (by conduction) close to the carrier 85 but may not heat sufficiently parts more distant from the carrier 85. By applying conventional heat in addition to the electromagnetic radiation, or a magnetic or electrical field, the whole of the flexible material of the strip 11 can be brought to the required temperature.

Figure 19 shows a modification to the Figure 18 arrangement. In this arrangement, additionally heater 126 is provided for heating the powder 150. Further, roller 128 is provided which presses the powder 150 against the carrier 85 in order to firmly bond the powder 150 to the carrier 85 to form coating 158. Preferably, the roller 128 is coated with PTFE in order to prevent the powder 150 adhering to the roller 128.

Figure 20 shows yet a further embodiment. In this embodiment additional rollers 130 are provided in pressing stage 132 to press the powder 150 against the carrier 85. Incorporated within the pressing stage 132 may be the inductive/capacitive heater for heating the carrier 85.

The rollers 128 may be arranged to move transversely with respect to the direction of travel X of the carrier 85 (that is, perpendicularly to the plane of the paper of the Figure). This allows the position of the coating 158 on the surface of the carrier 85 to be varied.

In a modification, two or more heat sources are provided which heat the sheet 100,102. For example, a first heat source may be provided at position Hl or H2 in Figure 15, and a second heat source may be provided at position H3 in a similar manner to the Figure 15 embodiment.

One to three or 10 slits 104 in the sheet 100 (Figure 9) per cm may be provided. The slits 104 may coincide in position with the slits, slots or apertures in the carrier 85 (although this will not usually be the case). Because the flexible material is firmly fixed with respect to the carrier by virtue of the sheet 100, it is not so important for the flexible material to pass through apertures in the carrier.

The carrier 85 may for example be 10cm in width. In Figure 6a the coating 101 may be 8cm in width (i.e. 80% of the width of the carrier 85 is coated). Alternatively, the entire width of the carrier may be coated. Typically the sheet 100, 102 (and the formed coating 101,103) are approximately 0.1mm in thickness.

The invention is applicable to strips comprising more than one carrier. A coating 101, 103 may be applied to each carrier or to only selected carriers.

In the known arrangement mentioned above, where a liquid agent or primer is applied to the carrier, the bond between the carrier and the flexible material is not significantly affected by subsequent heating. In contrast the coating 101,103,158 of the embodiments may be weakened by subsequent heating. This may be advantageous to facilitate recycling because the material of the carrier 85 and the flexible material may be separated from one another.