Field of the Invention The present invention relates to multilayer masking tapes, in particular but not exclusively to, improvements in separation characteristics of multilayer masking tapes. The present invention also relates to methods of manufacturing multilayer masking tapes that comprise a first layer, a second layer and a release region. Background of the Invention

Problems arise in obtaining a good finish to a masked edge when a substance such as paint or sealant to be applied to a non-masked off area is applied thickly or is applied in multiple distinct application stages. Example embodiments of the present invention aim to address problems associated with the prior art, whether identified herein, or otherwise.

Summary of the Invention

In one example embodiment there is provided a multilayer masking tape comprising: a first layer, and a second layer separably adhered to the first layer; characterised by further comprising a release region between the first layer and the second layer to aid separation of the second layer from the first layer.

In one example embodiment the second layer is arranged on the first layer such that an edge of the first layer corresponds to an edge of the second layer, and wherein the corresponding edges provide a masking edge for the multilayer masking tape.

In one example embodiment the corresponding edges are aligned with one another so as to present a masking edge that is common to both first and second layers.

In one example embodiment the second layer is arranged on the first layer such that first and second edges of the first layer correspond to respective first and second edges of the second layer, and wherein each pair of corresponding edges provides a masking edge for the multilayer masking tape.

In one example embodiment the first and second layers are of the same width as each other along the length of the multilayer masking tape. In one example embodiment the first and/or second layers are of constant width along the length of the multilayer masking tape.

In one example embodiment the release region is positioned away from a masking edge provided by the first layer, so as not to reduce adhesion between the first and second layers at said masking edge.

In one example embodiment the release region is positioned away from a masking edge provided by the second layer, so as not to reduce adhesion between the first and second layers at said masking edge.

In one example embodiment the release region is positioned away from masking edges provided by the first and second layers together, so as not to reduce adhesion between the first and second layers at said masking edges.

In one example embodiment the release region extends along the length of adhered portions of the first and second layers.

In one example embodiment the first and second layers comprise the same type of masking tape.

In one example embodiment the second layer comprises an adhesive surface for separably adhering the second layer to the first layer; and wherein the release region comprises a portion of the adhesive surface of the second layer having reduced adhesiveness.

In one example embodiment the second layer comprises an adhesive surface for separably adhering the second layer to the first layer; and wherein the release region comprises a release coating applied between the first and second layers. In one example embodiment the second layer comprises an adhesive surface for separably adhering the second layer to the first layer; and wherein the release region comprises a release sheet applied between the first and second layers.

In one example embodiment the second layer comprises an adhesive surface for separably adhering the second layer to the first layer; and wherein the release region comprises a portion of the adhesive surface at which no adhesive is provided.

In one example embodiment the first and second layers are visually distinguishable from one another. In one example embodiment the first layer and second layer are visually distinguishable from one another by different shapes, colours, markings or the like so that in use the presence of the first and/or second layer in the multilayer masking tape can be determined individually.

In one example embodiment the second layer comprises a built in region of weakness by which the second layer may be broken to aid separation of the second layer from the first layer in use. In one example embodiment the first layer comprises a built in region of weakness by which the first layer may be broken to aid separation of the first layer from a masked substrate in use.

In one example embodiment the first and/or second layer comprises self-adhesive masking tape.

In one example embodiment the multilayer masking tape may further comprise a third layer separably adhered to the second layer and still further comprising a release region between the second layer and the third layer to aid separation of the third layer from the second layer. Fourth and one or more further layers are also envisaged, arranged in a corresponding manner to the first and second layers as described above.

In another example embodiment there is provided a method of manufacturing a multilayer masking tape, the method comprising steps of: separably adhering a second layer to a first layer with a release region between the first layer and the second layer to aid separation of the second layer from the first layer.

In one example embodiment the step of separably adhering comprises placing the second layer on, e.g. on top of the first layer such that the first and second layers are adhered along one or more masking edges. Suitably, the release region is provided away from masking edges of the first and second layers.

In one example embodiment the method comprises providing a release coating or release sheet between the first and second layers to form the release region. Suitably, the method is performed on/uses/results in the production of a multilayer masking tape wherein the first layer and/or second layer and/or release region are as described in the multilayer masking tape of example embodiments set out herein. In still another example embodiment there is provided a method of masking off part of a substrate, the method comprising steps of:

masking off the part of the substrate with multilayer masking tape comprising: a first layer, a second layer separably adhered to the first layer, and a release region between the first layer and the second layer to aid separation of the second layer from the first layer; and

subsequently separating the second layer from the first layer making use of the release region.

Suitably, the method uses a multilayer masking tape wherein the first layer and/or second layer and/or release region are as described in the multilayer masking tape of example embodiments set out herein.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

Brief Introduction to the Drawings

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

Figure 1 shows a perspective view of a multilayer masking tape according to an example embodiment; Figure 2 shows an exploded perspective view of the multilayer masking tape of Figure 1 ; and

Figures 3 and 4 show the multilayer masking tape of Figure 1 arranged in use as part of a method of masking off part of a substrate according to an example embodiment. Description of Preferred Embodiments

Figures 1 and 2 show a perspective view and an exploded perspective view respectively, of a multilayer masking tape 10 according to an example embodiment of the present invention. The multilayer masking tape 10 comprises a first layer 1 , and a second layer 2 that is separably adhered to the first layer 1 . A release region 30 is provided between the first layer 1 and the second layer 2 to aid separation of the second layer 2 from the first layer 1 when the masking tape is used. The first and second layers 1 , 2 are conveniently provided as layers of self-adhesive masking tape. In the example embodiment of Figures 1 and 2 the release region 30 is provided by the presence of a release sheet 3 applied between the first and second layers 1 , 2. In the representation of Figure 1 a gap is shown between edges of the first layer 1 and the corresponding edge of the second layer 2. Although such a gap may be present during the process of manufacture of the multilayer masking tape, the thickness of the release sheet 3 is relatively small, and the second layer 2 will adhere to the first layer 1 so that the edges thereof stick to one another and provide a masking edge. The release region 30 provided by the release sheet 3 is positioned away from masking edges provided by the first and second layers together, so as not to reduce adhesion between the first and second layers at said masking edges. Without the presence of the release region 30, the adhesion between the first and second layers 1 , 2 would make separating the second layer 2 from the first layer 1 a difficult task. The release region extends along the length of adhered portions of the first and second layers 1 , 2 so that in use it is not important what length of tape is cut or produced in order to get effective separation starting from the end of the multilayer masking tape. The release region as described facilitates the separation without impacting on masking functionality for the first layer 1 , or the combination of the second layer 2 with the first layer 1 . In particular the release region as described facilitates the separation without impacting on masking functionality at both edges of the multilayer masking tape 10.

In the example embodiment of Figures 1 and 2, the same type of masking tape is used for the first and second layers 1 , 2, that is a masking tape having suitable adhesive properties to perform a masking function, and with the first and second layers 1 , 2 being of the same width as each other so that the second layer 2 can be arranged on the first layer 1 with the edges of the first layer 1 corresponding to the edges of the second layer 2. The release sheet 3 suitably also comprises a tape, such as a self-adhesive tape to stick to one or other of the first and second layers 1 , 2 in the multilayer masking tape structure.

In this way the embodiment of Figures 1 and 2 is arranged to provide masking edges when both first and second layers 1 , 2 are present, and to provide masking edges with the first layer 1 on separation of the second layer 2 from the first layer 1 . That is, the multilayer masking tape 10 provides corresponding edges that are aligned with one another so as to present a masking edge that is common to both first and second layers 1 , 2 on each of the two sides of the multilayer masking tape 10. The use of the masking edges of the first and second layers 1 , 2 together, and then for just the first layer will be described in more detail with reference to Figures 3 and 4 below. Figures 3 and 4 show multilayer masking tape according to an example embodiment arranged in use as part of a method of masking off part of a substrate. In this instance the substrate to be masked off is part of an aeroplane wing W. The first step is to mask off part of the substrate with the multilayer masking tape 10. In this example embodiment the multilayer masking tape 10 is placed along two sides of a joint on the wing. A first deposit of sealant S is then applied between the masked off parts and smoothed using a metal squeegee and given time to cure. Once curing is completed and the sealant has set the second layer 2 is removed from the first layer 1 and the process of applying sealant S is carried out for a second time.

The multilayer masking tape 10 in this example embodiment allows two separate applications of sealant S, but without the need to align a new layer of masking tape with the previous sealant edge when making the second application. The removal of the second layer 2 of the multilayer masking tape 10 avoids problems associated with any residue that the first application of sealant S may leave behind on top of the second layer 2. Using the same multilayer masking tape 10 for a second application of sealant S may not result in a sufficiently smooth edge to the sealed part of the wing W. In order to increase usability of the multilayer masking tape 10 the first and second layers 1 , 2 are visually distinguishable from one another, for example by having distinguishing colouration, markings or the like so that in use the presence of the first 1 and second layer 2 in the multilayer masking tape can be determined individually. As will be apparent, methods of manufacturing the multilayer masking tape described herein may comprise separably adhering a second layer to a first layer, with a release region between the first layer and the second layer to aid separation of the second layer from the first layer. The first and second layers used in manufacture may be of self-adhesive tape, and comprise the same specification such as width, adhesive tack etc. The step of separably adhering suitably comprises placing the second layer the first layer such that the first and second layers are adhered along one or more masking edges, and wherein the release region is provided away from masking edge(s) of the first and second layers. In manufacturing the embodiments described above the method further comprises providing the release sheet between the first and second layers to form the release region.

Some possible modifications, as alternative example embodiments will now be described in the context of the examples set out above. In the example embodiment of Figures 1 and 2 the corresponding edges at both sides of the multilayer masking tape 10 are masking edges, but in many instances the multilayer masking tape of example embodiments may provide only one masking edge. Equally, the alignment of the edges of the first and second layers may not correspond, so that there is a set-back, or set-forward of the edge of one layer relative to another. This could be achieved by partially overlapping the layers, or using first and second layers are of different width to each other. In other embodiments the first and/or second layers may not be of constant width along their length, to facilitate provision of one or more non-linear masking edges.

As described above, a release sheet, for example provided by a non-adhesive tape or by a tape which adheres to one or other of the first and second layers only, is a convenient way of forming the release region. In other embodiments the release region may be provided as a portion of the adhesive surface of the second layer that has reduced adhesiveness or no adhesiveness, either by virtue of the way the adhesive is applied, or the nature of the adhesive, or by some other means such as overlaying of a release coating such as a lacquer. When using the multilayer masking tape 10 separation of the second layer 2 from the first layer 1 will be started by peeling the second layer 2 at the end of tape 10, using the release region to start the process. If the end of the tape is not accessible, or in other circumstances, it may be desirable to cut through the multilayer masking tape, for example through at least the second layer thereof in order to provide a new end from which the separation of the second layer 2 can be started. In order to facilitate the provision of a new end, so that the risk of damage to any underlying substrate in use is reduced the second layer 2 suitably comprises a built in region of weakness such as point, line or area of weakness (not shown). The built in region of weakness may be provided along the length of the multilayer tape, either continuously or intermittently. The built in region of weakness may comprise a scored or cut region, for example produced by laser or by use of a die. Using the built in region of weakness the second layer 2 may be more easily broken, to thus aid in separation of the second layer 2 from the first layer 1 .

It will be appreciated that although two layer masking tapes have been described, the principles herein may be scaled up to cover three, four or more layers, as appropriate. The number of layers, tape width, tape material and type of adhesive used in the multilayer tape may be selected in example embodiments according to the intended substrate to be masked off and the substance that is to be applied to the non-masked area as is typical in the use of single layer masking tapes.

Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.