WO2015042128A2

WO2015042128A2 - Masking tape

Info

Publication number: WO2015042128A2
Application number: PCT/US2014/056056
Authority: WO
Inventors: Dyfrig E. Clement; Kin-Chau CHAN; Clive Bew; Martyn V. Hagedorn; Gareth M. Jones
Original assignee: 3M Innovative Properties Company
Priority date: 2013-09-20
Filing date: 2014-09-17
Publication date: 2015-03-26
Also published as: WO2015042128A3; GB201316765D0

Abstract

A method of making an edge masking strip for masking an edge of a substrate to be painted is disclosed. The method comprises the steps of: (i) providing a precursor edge masking strip material; (ii) adapting the precursor edge masking strip material so that it forms an edge masking strip having a first face adapted to attach to a mounting surface, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and (iii) adapting the structure of the second portion of the precursor edge masking strip material by either removing material from the precursor edge masking strip material or shaping the precursor edge masking strip material.

Description

MASKING TAPE

Background

The present invention relates to an edge masking strip for masking an edge of a substrate, the substrate having a surface to be spray painted.

Summary

When carrying out vehicle body repairs or refinishing motor vehicle bodywork, it is normally necessary to mask off the gap between adjacent panels or posts in order to prevent overspray entering the gap between the panels. For example, there exists a visible shut line or gap, which can be curved, between a static member (such as an A or B post of a vehicle) and a moveable member (such as a front or rear door). The width, depth and curvature of the gap vary depending on the model of the vehicle and the relative position of the static and moveable parts. Similarly a gap may exist between two static posts, or between two moving parts. Without any form of adequate sealing or masking of the gap, paint spray would tend to ingress into the gap, with any overspray producing an accumulation of paint in the gap. This results in an undesirable formation of paint runs on the interior surface of the gap, more particularly at the edge of at least one adjacent panel, which would require rectification. Rectification involves rubbing down of the paint runs, which is both time consuming and costly.

Conventional masking tapes, for preventing the flow of paint into such gaps, involve the application of a paint absorbing material such as an elongate foam tape to fill the gap between a moveable part of a vehicle such as a door, bonnet/hood or trunk/boot and an adjacent part/post of the vehicle. One face of the foam tape has a longitudinally extending strip of pressure sensitive adhesive enabling the foam tape to be secured at the edge of either a moving part or a static part in such a way that when the moving part closes onto the static part, a seal is made between the two parts. Unless the tape is very carefully positioned at the edge of the static part or the moveable part, movement of the moveable part can displace the foam so as to expose the adhesive. Since the adhesive does not absorb the spray paint, this results in the accumulation of paint giving rise to the formation of a ridge which is apparent tactio-visually. Excessive paint accumulation at the surface of the foam strip can cause parts of the foam to remain adhered to the painted paint when the remainder of the strip is pulled away, commonly known as "picking".

Various methods and devices have been developed and adopted in the art to overcome the drawbacks of the accumulation of paint spray around existing masking tapes. One area in particular is around the adhesive region, so as to allow the interior surface of the gap to be spray painted in such a manner that the edge of the paint work blends into the adjacent unpainted regions. WO 02/068556 teaches a foam masking tape comprising an elongate flat strip of foam material that has been bent around and attached to an adhesive strip of material to form a tube. To avoid the build-up of paint spray in the gap between two substrates the adhesive is shielded away from the paint spray by being located in a recess in the foam material.

WO 00/30761 teaches a sealing member that is substantially symmetrical in shape such as a rectangular or square shaped sealing member. An adhesive track is located mid-way between the opposite faces of the sealing member, creating a demarcation zone at the edge of the strip. This ensures that when the foam member is attached to the static part of the motor vehicle there is no adhesive exposed in the region of the demarcation zone. The open cell foam of the sealing member in the vicinity of the gap absorbs the paint overspray, thereby preventing a paint edge from building up. US201 1/0308710 teaches an elongate masking article that can be removably attached to a vehicle for masking a surface to be painted, the article being formed from a polymeric foam. It has been found that the presence of a skin on the external surface of the article results in an improvement in the quality of the paint edge produced on the adjacent panel surface. More specifically, the number of paint speckles that appear along the paint edge, which can give the edge a fuzzy appearance, is reduced, with consequential benefits to the overall appearance of the re-painted surface. It is believed that the formation of the speckles is inhibited by increasing the smoothness of the surface through the presence of the skin.

Another technique adopted by the skilled person involves inwardly folding lengthwise an edge of a strip of masking tape onto an adhesive side of the masking tape leaving a section of the adhesive side exposed lengthwise. The exposed adhesive section of the masking tape is then applied to an interior surface of a static part of the vehicle such that the non-adhesive section of the tape formed by the folded portion protrudes outwardly. A strip of foam based material is then adhered lengthwise to the masking tape before closing the moving part and spray painting the vehicle. The non-adhesive portion of the folded tape prevents the paint from coming into contact with the adhesive region and forming an undesirable ridge. This technique, known as "French masking", often results in a smoother paint line. However, such a masking technique is only suitable for masking simple geometric gaps. The inextensible nature of the masking tape reduces its ability to follow the contours of the interior surface of the static member easily. This is exacerbated when masking significantly curved profiles e.g. at the junction where the door post meets the floor of the vehicle. Due to the curvature of the gap, there is a tendency for the tape to lift away from the vehicle pillar/post, which often results in excessive paint build up. For some vehicles, the attached foam based material is compressed by the movable part to an extent that it protrudes outwardly from the gap. This causes paint to 'bridge' between the surface of the adjacent part and the edge of the foam. Such a build-up of paint results in the formation of a ridge with a rough paint edge when the foam and the tape are subsequently removed from the vehicle post. Furthermore, the application of this masking tape is a time consuming process since it requires the user to separately prepare the masking tape for application to the vehicle and subsequently apply a strip of foam based material onto the masking tape to mask the gap. Considerable skill in positioning the tape and foam correctly on the vehicle is also required. GB2486736 discloses an adaption of the above lengthwise folded masking tape with improvements to overcome the drawbacks mentioned above. GB2486736 teaches a pre-formed masking strip comprising a backing that is analogous to the masking tape described above, the backing having an adhesive region to fix the masking strip to an interior surface of a gap. A gap filler analogous to the foam material extends from the backing and is adapted to prevent paint flow into the gap. Instead of folding a strip of masking tape, in order to provide an adhesive free region in the vicinity of the paint line, GB2486736 teaches the provision of a spacer adapted to space the adhesive region of the backing away from the interior surface of the gap. This helps to achieve a smooth paint line on the substrate to be painted because the adhesive is positioned away and shielded from the paint line. In order to achieve a good quality paint line finish at an edge demarcated by the masking strip, the necessity of shielding the adhesive region from, or relocating the adhesive region out of contact with, the paint during spraying, has been appreciated. However, this technique is not effective all of the time and other factors may contribute to the accumulation of paint in the region between the backing of the masking strip and the masked surface.

There is a continuing desire to improve the finish of the edge of the new paintwork so that the result resembles the finish on a newly manufactured vehicle as closely as possible.

The present invention aims to address these problems by providing a method of making an edge masking strip for masking an edge of a substrate to be painted, comprising the steps of: i) providing a precursor edge masking strip material; ii) adapting the precursor edge masking strip material so that it forms an edge masking strip having a first face adapted to attach to a mounting surface, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and iii) adapting the structure of the second portion of the precursor edge masking strip material by either removing material from the precursor edge masking strip material or shaping the precursor edge masking strip material. Preferably, the step of removing material comprises the step of machining a channel or recess in the precursor edge masking strip material, said channel or recess having a cross-section with a substantially angled profile. More preferably, the step of removing material comprises the step of grinding a channel or recess in the precursor edge masking strip material, said channel or recess having a cross-section with a substantially angled profile.

The present invention also provides a method of making a masking strip for masking an interior surface of a gap between a first substrate and a second substrate positioned adjacent the first substrate, comprising the steps of: i) providing a precursor edge masking strip material; ii) adapting the precursor edge masking strip material so that it forms an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray; iii) providing a precursor gap filler material; iv) forming a profile in the precursor gap filler material by removing material from the precursor gap filler material and/or folding at least a portion of the precursor gap filler material; and v) securing the precursor gap filler material to the precursor edge masking strip material such that a portion of a gap filler extends at an angle from the second face of a masking strip.

Preferably, the profile is one of: substantially rectangular, substantially angled, substantially curved or a channel or recess.

The step of forming a profile preferably comprises the step of forming a channel or recess in the precursor gap filler material by folding the precursor gap filler inwardly in two and securing opposed portions of the precursor gap filler material along its length such that the channel or recess lies adjacent to the folded portions of the precursor gap filler material.

Preferably, the method further comprising the steps of; vi) adapting the opposed portions of the precursor edge masking strip material so as to form two edge masking strips positioned edge-to-edge along their length; vii), securing the precursor edge masking strip material to the channel or recess in the precursor gap filler material; and viii) separating lengthwise the assembled strip so as to create two masking strips. Preferably, the step of securing the precursor gap filler material to the precursor edge masking strip material comprises the steps of a) applying an adhesive strip to the precursor gap filler material, and, b) adhering the precursor gap filler material to the precursor edge masking strip material. Said at least one folded portion of the precursor gap filler material is preferably adhered to the adhesive strip so as to leave a width of exposed adhesive strip adjacent the folded portion of the precursor gap filler material. The method may also comprise the steps of vi) adapting opposed portions of the precursor edge masking strip material so as to form two edge masking strips positioned edge-to-edge along their length, vii) securing the precursor edge masking strip material to the channel or recess in the precursor gap filler material to form an assembled strip; and, viii) separating lengthwise the assembled strip so as to create two masking strips.

The invention yet further provides a method of forming a masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, comprising: a) adapting a precursor masking strip material so that it forms a masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip; and, b) forming the masking strip as a single body such that the edge masking strip is integral with the gap filler. The masking strip is preferably formed by moulding or extruding.

The method may further comprise the step of thermoforming the precursor masking strip material around at least one shaped mould, wherein the shaped mould has a first forming face representing the edge masking strip and a second forming face representing the gap filler such that the resultant thermoformed masking strip is shaped with a first leg forming the edge masking strip and a second leg forming the gap filler.

Preferably the shaped mould has a substantially triangular cross section. The present invention also provides a method of forming a continuous profile of a predetermined shape extending along a strip of a formable material, comprising the steps of; i) thermoforming the material against at least one shaped mould to form a strip of profiled material; and, ii) indexing along a length of the mould such that adjacent portions of the profiled material are seamlessly joined by overlapping.

Preferably the continuous profile is a masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, the masking strip comprising an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip.

Preferably the step of thermoforming the formable material comprises the step of vacuum forming the formable material.

The present invention also provides a thermoformed masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, the masking strip comprising an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip, integral with the second face of the masking strip.

The present disclosure includes, but is not limited to, the following exemplary Embodiments:

Embodiment 1. A method of making an edge masking strip for masking an edge of a substrate to be painted, comprising the steps of:

i) providing a precursor edge masking strip material;

ii) adapting the precursor edge masking strip material so that it forms an edge masking strip having a first face adapted to attach to a mounting surface, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and

iii) adapting the structure of the second portion of the precursor edge masking strip material by either removing material from the precursor edge masking strip material or shaping the precursor edge masking strip material.

Embodiment 2. The method as in Embodiment 1, wherein the step of removing material comprises the step of machining a channel or recess in the precursor edge masking strip material, said channel or recess having a cross-section with a substantially angled profile.

Embodiment 3. The method as in Embodiment 1, wherein the step of removing material comprises the step of grinding a channel or recess in the precursor edge masking strip material, said channel or recess having a cross-section with a substantially angled profile. Embodiment 4. A method of making a masking strip for masking an interior surface of a gap between a first substrate and a second substrate positioned adjacent the first substrate, comprising the steps of:

i) providing a precursor edge masking strip material;

ii) adapting the precursor edge masking strip material so that it forms an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray;

iii) providing a precursor gap filler material;

iv) forming a profile in the precursor gap filler material by removing material from the precursor gap filler material and/or folding at least a portion of the precursor gap filler material; and

v) securing the precursor gap filler material to the precursor edge masking strip material such that a portion of a gap filler extends at an angle from the second face of the masking strip.

Embodiment 5. The method as in Embodiment 4, wherein the profile is one of: substantially rectangular, substantially angled, substantially curved or a channel or recess.

Embodiment 6. The method of Embodiment 4, wherein the step of forming a profile comprises the step of forming a channel or recess in the precursor gap filler material by folding the precursor gap filler material inwardly in two and securing opposed portions of the precursor gap filler material along its length such that the channel or recess lies adjacent to the folded portions of the precursor gap filler material.

Embodiment 7. The method of Embodiment 6, further comprising the steps of;

vi) adapting the opposed portions of the edge precursor masking strip material so as to form two edge masking strips positioned edge-to-edge along their length;

vii) securing the precursor edge masking strip material to the channel or recess in the precursor gap filler material to form an assembled strip; and

viii) separating lengthwise the assembled strip so as to create two masking strips.

Embodiment 8. The method as in any of the Embodiments 4 to 7, wherein the step of securing the precursor gap filler material to the precursor edge masking strip material comprises the steps of a) applying an adhesive strip to the precursor gap filler material; and

b) adhering the precursor gap filler material to the precursor edge masking strip material. Embodiment 9. The method of Embodiment 8, wherein said at least one folded portion of the precursor gap filler material is adhered to the adhesive strip so as to leave a width of exposed adhesive strip adjacent the folded portion of the precursor gap filler material.

Embodiment 10. The method of Embodiment 4, further comprising the steps of:

vi) adapting opposed portions of the precursor edge masking strip material so as to form two masking strips positioned edge-to-edge along their length,

Embodiment 1 1. A method of forming a masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, comprising:

a) adapting a precursor masking strip material so that it forms an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip; and

b) forming the masking strip as a single body such that the edge masking strip is integral with the gap filler.

Embodiment 12. The method of Embodiment 1 1, wherein the masking strip is formed by moulding or extruding.

Embodiment 13. The method of Embodiment 1 1 or 12, further comprising the step of thermoforming the precursor masking strip material around at least one shaped mould, wherein the shaped mould has a first forming face representing the edge masking strip and a second forming face representing the gap filler such that the resultant thermoformed masking strip is shaped with a first leg forming the edge masking strip and a second leg forming the gap filler.

Embodiment 14. The method of Embodiment 13, wherein the shaped mould has a substantially triangular cross section. Embodiment 15. A method of forming a continuous profile of a predetermined shape extending along a strip of a formable material, comprising the steps of; i) thermoforming the material against at least one shaped mould to form a strip of profiled material; and

ii) indexing along a length of the mould such that adjacent portions of the profiled material are seamlessly joined by overlapping.

Embodiment 16. The method of Embodiment 15, wherein the continuous profile is a masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, the masking strip comprising an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip.

Embodiment 17. The method of any of Embodiments 15 or 16, wherein the step of thermoforming the formable material comprises the step of vacuum forming the formable material.

Embodiment 18. A thermoformed masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, the masking strip comprising an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip, integral with the second face of the masking strip.

The present invention and its preferred features and advantages are further described below with reference to illustrative embodiments shown in the drawings.

Brief Description of the Drawings

Fig. 1 is a schematic view of a gap between two substrates to be painted;

Fig. 2 is a schematic view of a gap between a door and a 'C post of a vehicle;

Fig. 3 is a side view of a masking strip to mask the gap shown in Fig. 1 comprising an edge masking strip of the present invention and a gap filler;

Fig. 4 is an illustration of a gap formed between two metal shims to mimic the space between the edge masking strip of the masking strip and the surface adjacent to an edge of a substrate to be painted; Fig. 5 is a schematic side view of an edge masking strip when attached to a surface adjacent to an edge of a substrate to be painted;

Fig. 6 is a schematic view showing various differently profiled masking strips embodying of the present invention, in which each profile forms a backing that is differently spaced from the surface adjacent to the edge of the substrate to be painted;

Fig. 7a is a side view illustration of a method of approaching a grinding wheel at an angle to a strip of precursor edge masking strip material so as to machine a channel having an angled cross- sectional profile in the precursor edge masking strip material;

Fig. 7b is also is a side view illustration of a method of approaching a grinding wheel at an angle to a strip of precursor edge masking strip material so as to machine a channel having an angled cross- sectional profile in the precursor edge masking strip material;

Fig. 8a is schematic view of an abrasive covered wheel having a flat grinding face;

Fig. 8b is a schematic view of an abrasive covered wheel having an angled grinding face;

Fig. 9 is a schematic view of an abrasive covered wheel having a grinding face with a multi-angle face profile;

Fig. 10 is a schematic view of a precursor edge masking strip material having a substantially trapezoidal cross-section used to form two edge masking strips of the present invention, back-to- back;

Fig. 1 1 is a schematic view of a precursor edge masking strip material adapted to generate two edge masking strips according to an alternative embodiment of the present invention;

Fig. 12 is a schematic view of an edge masking strip whereby the edge masking strip is bent at an angle to create a space between the non-contact region of the edge masking strip and the surface adjacent to the edge of the substrate to be painted;

Fig. 13(a) is a schematic view of an edge masking strip according to a second embodiment of the present invention whereby the edge masking strip is bent at two locations to create three face portions, each face portion being angled with respect to each other;

Fig. 13(b) is a schematic view of an edge masking strip according to a third embodiment of the present invention similar to that of Fig. 13(a), but in which a portion of the edge masking strip is curved;

Fig. 13(c) is a schematic view of the backing shown in Fig. 13(b) or Fig. 13(a) applied to an interior surface adjacent to an edge of a substrate to be painted;

Fig. 14(a and b) are schematic views of an precursor edge masking strip material, in which opposite portions of each precursor masking strip material is adapted with space defining features, each space defining feature being as the edge masking strip as shown in Figs. 12 and 13b respectively;

Fig. 15(a) is a schematic side view of a gap filler showing a recess or channel cut out from a portion proximal to the end of the gap filler material having a substantially rectangular profile; Fig. 15(b) is a schematic side view of a gap filler shown in Fig. 15a, encouraged to extend from the edge masking strip when attached to the edge masking strip of the present invention;

Fig. 16(a) is a schematic side view of a gap filler in another embodiment of the present invention showing a recess or channel cut out from a portion proximal to the end of the gap filler material having a substantially angled profile;

Fig. 16(b) is a schematic side view of a gap filler shown in Fig. 16a, encouraged to extend from the edge masking strip when attached to the backing of the present invention;

Fig. 17 is a schematic side view of a masking strip in another embodiment of the present invention, whereby the gap filler is folded inwardly in two;

Fig. 18 (a to h) shows schematic views of the processing steps used to create a masking strip as shown in Fig. 17;

Fig. 19 is a schematic view of apparatus to machine a channel or recess in the gap filler material to create the masking strip shown in Fig. 15 as an alternative to folding the edges of the gap filler material as shown in Figs. 18(b to d);

Fig. 20 is a schematic view of apparatus to machine a channel or recess in the gap filler material to create the masking strip shown in Fig. 16b as an alternative to folding the edges of the gap filler material as shown in Figs. 18(b to d);

Fig. 21 is a schematic illustration of a folding or gathering device for folding the edges of the gap filler inwardly in two according to another embodiment of the present invention;

Fig. 22 is a top view of the folding or gathering device of Fig. 21 ;

Fig. 23 is a side view of the folding or gathering device of Fig. 21 ;

Fig. 24(a) is a cross-section on the line X-X of Fig. 22;

Fig. 24(b) is a cross-section on the line Y-Y of Fig. 22;

Fig. 25 is a schematic view of a mould/tool profile for vacuum forming a masking strip according to another embodiment of the present invention;

Fig. 26(a and b) are a side view and a cross-sectional view of the mould shown in Fig. 25 showing the vacuum drill holes located at strategic positions along the mould/tool face;

Fig. 27 is a schematic illustration of the thermoformable material in relation to the mould/tool shown in Fig. 25 or Fig. 26;

Fig. 28 is a schematic illustration of the processing step of applying the vacuum and heating to the thermoformable material in proximity to the mould/tool shown in Fig. 25 or Fig. 26;

Fig. 29 is a schematic illustration of the thermoformable material taking the shape of the mould/tool face shown in Fig. 25 or Fig. 26;

Fig. 30 (a and b) shows a schematic top view and side view of the vacuum moulded masking strip produced by the mould/tool shown in Fig. 25 or Fig. 26 according to an embodiment of the present invention; and

Fig. 31 is a diagram illustrating a process of forming the masking strip shown in Fig. 18, 19 or 20. Detailed Description of the Drawings

In the following description reference to "paint" should be understood to include a base coat, paint, (the coloured paint layer seen on vehicles) and clear coat (also known as lacquer), and a smooth paint edge includes an edge that is smooth to touch, which does not cause a finger nail to catch against the edge of the paint coating. The types of defects encountered on the interior surface of a gap between two substrates leading to a rough paint edge surface or a rough surface adjacent to an edge of the substrate to be painted as result of inferior masking strips, are:

a) Overspray - the presence of visibly noticeable droplets of paint on the surface adjacent to the edge of the substrate which it is intended to paint;

b) Picking - the breaking away and transfer of the masking material, in particular of the foam material when the masking strip is pulled away from a surface adjacent to an edge of the substrate to be painted. This typically occurs due to the accumulation of paint adjacent the masking strip adhesive leading to excess paint penetrating into the pore structure of the foam material of the masking strip. This results in a section of the foam material being adhered strongly to the edge of the substrate causing it to remain behind when the rest of the masking strip is pulled away from the substrate once the paint has dried;

c) Impression - following the accumulation of paint around the masking strip and the surface adjacent to the edge of the substrate, particularly in the vicinity of the adhesive, there is a tendency for the non-adhesive region of the masking strip to touch or make contact with the wet paint leaving an impression in the paint;

d) Ridge or prominent paint line - this is a common type of defect found in conventional masking tapes and is as a result of the accumulation of paint in areas of the masking strip possessing little or no paint absorption characteristics, such as in the vicinity of the masking strip adhesive.

The following description is made with reference to a particular embodiment of the present invention, involving masking the interior surface of a gap between two substrates to be painted, each of the substrates having a surface and a further surface to be spray painted. However, the present invention is also applicable to spray painting any substrate having an edge, whereby a smooth paint line finish is required on a surface adjacent to the edge of the substrate to be painted or at that edge. Hence the reference to a gap between two substrates is not intended to limit the application of the invention in any way. The term "gap" is therefore used to indicate such a spatial relationship between two substrates, and the term "space" to indicate the space between a substrate and either an edge masking strip or a backing. It has been found that by controlling the size and shape of the space the depth paint penetrates into the space can be controlled and minimised. The shape of the space is controlled by the structure of the masking strip, such as providing a spacing means that spaces the strip away from the edge of the substrate, or shaping portions of the masking strip adjacent the edge. This prevents paint from accumulating in and around the region surrounding the space, resulting in a smooth paint line finish on the substrate to be painted. More particularly, a smooth paint line finish can be achieved at the edge of the substrate at or near the mouth of a gap between two substrates. The present invention is applicable to any substrate having an edge and a surface to be spray painted, where the application of spray paint onto the substrate surface ideally results in a smooth paint line finish on a surface adjacent to the edge, a surface adjacent to the edge of the substrate lying in a different plane, or a surface remote from the substrate surface. Examples of substrates having a surface to be spray painted and an edge include but are not limited to parts of a motor vehicle, such as an A, B, C or D post, panel edge, wing, bonnet, boot or other sealing area. The present applicant has found that by configuring the edge masking strip so that, in use, the edge masking strip cooperates with the surface adjacent to the edge of the substrate to be painted to generate a space with an open end in line of sight of the paint spray and having a controlled shape and size, paint can be effectively excluded from entering deeply and accumulating in this space. This, in combination with shielding the adhesive region from the paint, results in a good paint line finish more consistently than the previously known techniques described above.

Without wishing to be bound by theory, it is believed that during spraying, there is a build-up of air turbulence at the mouth of the space, which creates a build-up of pressure that creates a resistance to penetration of paint into the space. US6793998 recognises that turbulence can occur around the opening or edges of the masking causing an uneven application of the paint to the surface to be treated. The degree of air turbulence and the depth of penetration of the paint into the space will depend on a host of variables, including, but not limited to: the air pressure of the spray gun; viscosity of the paint; ambient temperature; and the size and shape of the space between the edge masking strip and the mounting surface to which edge masking strip is attached. By controlling the shape and size of the space such as width and/or depth of the space, the fluid dynamics can be tailored so as to effectively exclude paint from entering or penetrating further into the space. In too wide a space, the hydrostatic pressure of the paint fluid exceeds the pressure built up in the space resulting in the paint travelling further into the space. Too narrow a space results in the paint fluid 'bridging' across the space due to the surface tension of the paint, resulting in an undesirable prominent paint line. The factors controlling the shape and size of the space will not only depend on the shape and size of the edge masking strip, but also on the shape and dimensions of the substrate with which edge masking strip cooperates. For example, in the case of a vehicle, the substrate could be a static substrate, such as car body panel, and the surface adjacent to the edge of the substrate could form part of an interior surface of a gap between the static part and a moveable part, such as a door. There are a wide variation in the dimensions and shapes of gaps between such static and moveable members depending upon the model of the vehicle under consideration. For example, the gap between a front door of a vehicle and the "A" post (which supports the door hinges) may differ from the gap between the door and the "B" post (which supports both the catch for that door and the hinges for the rear door), and may differ again from the gap between the rear door and the "C" post (which supports the catch for the rear door). The edge masking strip can be tailored to cater for the wide variations in the shape and size of the substrate so as to provide the necessary space that will function to exclude paint from penetrating within the space created. More specifically, the edge masking strip is provided with a first face, said first face comprising a first portion, adapted to contact a mounting surface on a substrate, and a second portion. The second portion is adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray. The size and/or shape of the space is determined by the structure of the first portion and/or second portion so as to substantially exclude paint from penetrating the space. There are numerous ways to configure the structure of the first portion and/or the second portion of the edge masking strip to achieve this effect. One option comprises the step of adapting the surface of the edge masking strip so that, in use, the surface of the second portion of the edge masking strip cooperates with the mounting surface adjacent to the edge of the substrate to generate a space of a predetermined shape. Preferably, the structure of the first portion and/or the second portion of the edge masking strip is adapted so that, in use, the second portion of the edge masking strip and the mounting surface adjacent to the edge of the substrate surface to be painted cooperate to create a space that is substantially "V" shape. A substantially 'V shaped space allows the width of the space to decrease with increasing depth. Consequently the resistance experienced by the paint increases with depth so that further penetration of the paint in the space is prevented. In turn, this effectively controls the neat visual appearance of the paint line.

The space bound by the mounting surface of the substrate and the second portion of the edge masking strip can be determined by either adapting the structure of the second portion in cooperation with the mounting surface or, equally, the structure of the first portion in contact with the mounting surface. This is so as to encourage the second portion to be spaced apart from the mounting surface or, alternatively, a combination of both the first portion and the second portion to be spaced apart. The structure of the first portion and/or the second portion can alternatively be adapted by machining to remove material from the first portion and/or the second portion, for example, by grinding.

The shape of the space is not restricted to being 'V shaped and other appropriate shapes are permissible so as long as the space functions to exclude the paint from penetrating into the space. Optionally, at least one face or side of the space has a curved profile. To that end, the second portion of the edge masking strip may be provided with a curved profile. Preferably, the first portion of the edge masking strip is angled with respect to the second portion so that, in use, a space is generated of a shape and size bound by the second portion and the mounting surface adjacent to the edge of the substrate. This results in paint being substantially prevented from penetrating the space.

The structure of the first portion and/or the second portion of the edge masking strip may be adapted by providing spacing means configured to space the edge masking strip (at the second portion) away from the mounting surface adjacent to the edge of the substrate to be painted. This is an alternative to adapting the surface of the edge masking strip by removing material from the edge masking strip, another option to control the spacing between the edge masking strip and the mounting surface of the substrate to which the edge masking strip is attached. The shape and/or size of the spacing means can be controlled such that the space formed can function to exclude paint from penetrating into the space as discussed above.

The edge masking strip may be formed as a single body wherein the first portion is angled with respect to the second portion so that, in use, the second portion cooperates with the mounting surface adjacent to the edge of the substrate to be painted to generate a space of a predetermined size and/or shape. Preferably, the first portion is bent with respect to the second portion. Alternatively, the edge masking strip comprises a third portion located between the first portion and the second portion, said third portion being angled with respect to the first portion and the second portion. In this situation, the third portion is bent with respect to the first portion and the second portion. Thus, when attaching the edge masking strip to the mounting surface adjacent to the edge of the substrate by means of the first portion, the non-contact face of the edge masking strip defines a space of a predetermined shape bounded by the second portion and/or the third portion and the mounting surface. Such an edge masking strip is preferably formed by the process of moulding or extruding.

Fig. 1 is a schematic view of a gap 1 between two substrates 2, 3 to be painted and Fig. 2 is an illustration of the masking according to the invention as applied between a door 10 and a 'C post 12 of a vehicle. In Fig. 1, the gap 1 is formed between a static part 2 and a moveable part 3, each of which comprises a substrate to be painted. In the example shown in Fig. 1 and illustrated further in Fig. 2, the static part 2 is a 'C pillar 12 and the moveable part 3 is a door 10. Suppose the external surface of a door 10 and/or a rear panel 1 1 are to be painted by spraying. In order to prevent paint from penetrating into the gap formed between the door 10 and the 'C pillar 12, the interior surface of the gap formed between the door and the 'C pillar is masked. However, this concept also extends to other static and moveable vehicle parts. The static part 2 presents a first substrate surface to be painted and the moveable part 3 presents a second substrate surface to be painted. The gap 7 comprises two interior surfaces 5, 6, with the first interior surface 5 representing the interior surface of the static part 2, and the second interior surface 6 representing the interior surface of the moveable part 3. The first 5 and the second 6 interior surfaces lie in a different plane to the first 2 and second 3 substrate surfaces to be spray painted. The top of the gap 7 is defined as coinciding with the edges of the first 2 and second 3 substrates to be painted.

The interior surface 6 of the moveable part 3 comprises a curved surface having a turning point T (proximal to the edge of the moveable part 3), which is effectively determined by the thickness of the material forming the outer shell of the moveable part 3. Due to the curvature of the interior surface 6 of the moveable part 3, a paint line PL_m naturally forms on the interior surface of the moveable part 3 at the boundary between where the interior surface 6 of the moveable part 3 is exposed externally, i.e. in line of sight of the paint spray, and the region that is not exposed to the paint falling below the paint line, PL_m. The paint line PL_m typically lies adjacent to or at the turning point T of the curved interior surface, i.e. proximal to the edge of the moveable part 3. Due to the structure of the interior surface 6 of the moveable part 3, paint naturally tends to rest at the turning point, T. Thus, to achieve a smooth paint line finish on the interior surface 6 of the moveable part 3, ideally there should be no or little contact between the masking strip and the curved portion of the interior surface 6 of the gap 1 so as to allow the curved surface of the moveable part 3 to dictate the formation of a smooth paint line finish.

However, the situation tends to be different for the static part 2. As demonstrated in Fig. 2 and shown in the cross-section in Fig. 1, the interior surface 5 of a static part 2 generally comprises a straight portion that extends deeper into the vehicle shell. As shown in Figs. 1 and 2 both the interior surfaces 5, 6, lie in a different plane to the surface of the substrates 2, 3 to be spray painted. In the particular example shown in Fig. 2, the interior surfaces 5, 6 lie in a different plane to the exterior surface of the door 10 and the rear panel 1 1. A large portion of the interior surface 5 of the static part 2 is exposed to the paint or is susceptible to being prone to contain defects through the ingress of paint, and thus, the treatment of the interior surface 5 of the static part 2 (the surface adjacent to the edge of the substrate 2) to achieve a smooth paint line finish would generally be different to that of the moveable part 3. Although, ideally, there should be minimal or no contact between the masking strip and a portion of the interior surface 5 of the static part 2, the positioning of a paint line, PL_S, (see Fig. 5) formed on the static part 2 is dependent on the positioning of the masking strip on the interior surface 5 of the static part 2. When the masking strip is applied close to the top of the gap 1 , the paint line, PL_S, is formed on the static part 2, close to the top 7 of the gap 1. Since the profile of the interior surface 6 of the moveable part 3 is different to the profile of the interior surface 5 of the static part 2, the method of achieving a smooth paint line on the interior surface 5 of the static part 2 is different to that used on the moveable part 3, which has a largely curved interior surface 6. Thus, the masking strip has to be engineered to function differently on the moveable part 3 than on the static part 2. The static part 2 presents the most challenging area in which to achieve a smooth paint line finish.

Since to achieve a smooth paint line finish, it is necessary to treat each interior surface of the gap formed between the two substrates 2, 3 differently, the method to achieve a smooth paint line finish between the masking strip and the static part 2 and between the masking strip and the moveable part 3 will be described separately.

The edge masking strip 14 shown in Fig. 3 has a first face 18 and second face 20 opposite the first face 18, the first face 18 having an adhesive region 23 to fix the masking strip 16 to the interior surface 5 of the gap (usually the static part 2 as shown in Fig. 3) and a non-contact region 24. The interior surface 5 of the gap 1 forms a mounting surface to fix the masking strip 16 to. For ease of explanation, the adhesive region 23 on the first face 18 of the edge masking strip 14 is provided on a first portion 22 of the edge masking strip 14, and the non-contact region of the edge masking strip is provided on a second portion 24, i.e. the first face 18 of the edge masking strip is divided into a first portion 22 and a second portion 24. In the particular embodiment of the present invention, the non- contact region (or second portion) 24 of the edge masking strip 14 is offset at a distance 27 from the interior surface 5 of the gap 1 to define a space 26. The width and/or height of the space 26 can be controlled so as to substantially exclude paint from penetrating this region as will be discussed further below. A gap filler 28 extends from the edge masking strip 14, more particularly from the second face 20 of the edge masking strip and is adapted to prevent paint flow into the gap. Here, the gap filler 28 has a proximal end 29a and is crimped where this proximal end 29a is joined to the edge masking strip, such that an angle ΘΟΑΡ is created between the edge masking strip and the gap filler. The crimping is formed by placing the gap filler 28 under pressure during manufacture to reduce the volume of the gap filler 28 at the join significantly.

As demonstrated in Fig. 3, the masking strip 16 is engineered such that, in use, the gap filler 28 is positioned below the paint line, PL_m, to present a 'contactless' free zone in the vicinity of the turning point, T, in order to achieve a smooth paint line finish at or in the region of the turning point, T. For an angle ΘΟΑΡ in the range 30 to 90° (measured between the edge masking strip 14 and the gap filler 28 at the proximal end 29a of the gap filler 28) prior to installation of the masking strip or with the moving part open, there will be minimal or no contact between the gap filler and a portion of the second interior surface 6 of the gap 1 at or in the region of the paint line, PL_m. When the moveable part 3 is closed, it contacts and resiliently deforms the gap filler 28 into a generally curved shape, as shown in Fig. 3. The gap filler 28 is based on a flexible, compressible and/or conformable material, and may be a foam like material, preferably a foam material such as a polyurethane foam, for example, X4200AM, available from Caligen Foam LTD, Broad Oak, Accrington, Lancashire, BB5 2BS, United Kingdom. The material forming the edge masking strip 16 of the masking strip 14 is based on a flexible, compressible and/or conformable material, e.g. polyethylene foam material. An example of a suitable polyethylene foam material is Aveolit TA1001 foam, available from Sekisui Alveo AG, Queens Chambers, Eleanors Cross, Dunstable, Bedfordshire, LU6 1 SU, United Kingdom.

Edge Masking Strip

The following description will focus on fabricating an edge masking strip as adapted to achieve a smooth paint line finish on a surface of the substrate or mounting surface, adjacent the edge of the substrate, to which the edge masking strip 14 is attached (see Fig. 5). The edge masking strip 14 may or may not be used together with other components, such as a gap filler 28, to form a completed masking strip 16, as discussed in more detail below. The edge masking strip 14 of the present invention is therefore applicable for masking the surface adjacent to an edge of any substrate alone or in conjunction with other masking components where necessary. For example, with reference to Fig. 1, the edge of the substrate could be the edge of the static part 2 and the surface adjacent to the edge of the substrate the interior surface 5 that lies in a different plane to the surface of the substrate 2 to be spray painted. The same applies to the moveable part 3. For ease of explanation of the properties of the edge masking strip 14, the following description will describe the edge masking strip when arranged to cooperate with the static part of a vehicle, e.g. the 'C pillar 12 of a vehicle as shown in Fig. 2. However, the static part is not restricted to the 'C pillar and could be extended to the other pillars of a vehicle, e.g. the Ά', 'B' or 'D' pillar of a vehicle or at other shut lines, e.g. at the bonnet, boot, or fuel filler cap. Equally, it could be attached to the moveable part 3 of the vehicle in which the interior surface is shaped with substantially straight portions that are largely exposed to the external surface, i.e. in line of sight of the paint. Non-automotive applications are also envisaged. It has been found that by controlling a space between a non-contact region of the edge masking strip 14 or masking strip 16 (not shown) (i.e. the second portion 24) and the interior surface 5 of the substrate on which the edge masking strip 14 or masking strip 16 is mounted, paint can be effectively excluded from travelling further into this space. This therefore prevents paint from accumulating in this region, resulting in a smooth paint line finish on the mounting surface adjacent to an edge of the substrate to be painted. This phenomenon can be demonstrated by artificially creating spaces of known width and depth with the sole purpose of demonstrating that the size of the space has an effect on the penetration depth of paint into the space. The term "size" should be taken to mean the combination of the overall volume and shape of the space. Spaces of different width and/or depth were created by spacing apart metal shims 38 of different thicknesses as shown in Fig. 4. The interior surface region 39 in the vicinity of the gap 36 formed by the spaced apart metal shims was spray painted and investigated to establish the presence of any paint, sprayed as indicated by arrows P, that has penetrated into the gap. Table 1 details the visual observations on the interior surface 39 of the gap formed between the metal shims 38 at different widths and/or height of the gap 36, whereby the height of the gap is varied by using metal shims of different heights and the width of the gap is varied by spacing apart the metal shims at different spaces. Table 1 clearly demonstrates that not only the height but most importantly the width of the gap 36 influences the depth of penetration of paint into the gap 36. At small widths, in the particular the example where the gap 36 was set at 50μηι in width, no paint was observed in the gap, more particularly none was observed on the interior surface 39 of the gap. Thus, it can be concluded that as the width of the gap 36 decreases, the amount of paint being able to travel into the bottom of this region formed by the space reduces. This also demonstrates that the deeper the space 36, the more the amount of paint travelling to the bottom of the spaced region also reduces. Although no quantitative measure was made, the results were assessed qualitatively. Substantially excluding paint from the space should be taken to mean that there was substantially no paint coverage of the interior surface of the space visible to the naked eye.

Table 1 : Observations on the interior surface between the metal shims

Similarly, the edge masking strip 14 of the masking strip 16 can be configured so that when attached to the interior surface 5 of a substrate 2, such as the 'C pillar of a vehicle, the edge masking strip 14 cooperates with the interior surface 5, which forms the mounting surface of the substrate to a create space 26 so as to effectively exclude paint from penetrating into this region (see Fig. 5). The space 26 represents the region bound by the edge masking strip 14 and the interior surface 5 to which the masking strip 14 is attached, i.e. the area between the non-contact region (second portion 24) of the edge masking strip 14 and the interior surface 5 adjacent to the edge of the substrate 2. In the particular example shown in Fig. 5, the non-contact region 24 of the edge masking strip 14/masking strip 16 adjacent the interior surface 5 is tapered or is formed with an angled profile that cooperates with the interior surface 5 at an angle Θ_Β, measured between the non-contact region 24 and the interior surface 5. Thus, the first face 18 of the edge masking strip 14 proximal to the interior surface 5 has a first portion 22 and a second portion 24, the first portion 22 being angled with respect to the second portion 24 (see Fig. 5). The region of adhesive 23, in this example, a strip of pressure sensitive adhesive, for attaching the edge masking strip 14 to the interior surface 5 extends along a portion of the first portion 22, and the non-contact region is formed by the second portion 24. Although, in the particular embodiment shown in Fig. 5, the non-contact region 24 is formed by the second portion 24, the non-contact region of the edge masking strip is not restricted to being the second portion 24 alone, as the adhesive strip 23 does not necessarily extend over the entire face of the first portion 22 of the edge masking strip 14. Thus, a portion of the first portion 22 of the edge masking strip 14 may also represent the non-contact region of the edge masking strip 14. The edge masking strip 14 is therefore attached to the substrate 2 so that the structure of the second portion 24 is adapted to provide a tapered surface 44 that cooperates with the interior surface 5 so as to create a space 26 bound by the tapered surface 44 and the interior surface 5 having a substantially a 'V shaped profile as shown in Fig. 5.

The edge masking strip 14 is arranged so that the open end or the mouth 48 of the space 26 is in line of sight of the paint spray. However, the structure of the second portion 24 is not restricted to a tapered surface and other geometric shapes are permissible so that the space 26 bounded by the interior surface 5 of the gap 7 and the non-contact region 24 of the edge masking strip 14 is not restricted to a substantially 'V shaped profile. Other shapes are permissible, such as a substantially rectangular space, which function so as to exclude paint from penetrating into this region. For example, the structure of the second portion 24 forming the non-contacting region 24 of the edge masking strip 14 does not necessarily need to have straight face profiles but can have a substantially curved profile. Moreover, the space is not necessarily created by adapting the structure of the second portion 24 since the space can be created by adapting the structure of the first portion 22 that is mounted on the interior surface 5 of the gap 7 so as to encourage the second portion 24 to sit spaced apart from the interior surface 5. For example, this can be envisaged by attaching the edge masking strip 14 to the interior surface 5 upside down. In the particular example shown in Fig. 5, a V-shaped profile provides a space 26 whereby the width of the space decreases with increasing depth in the space. The width 26 of the space can be controlled by controlling the angle, Θ_Β, the tapered profile makes with the vertical as shown in Fig. 5.

Table 2 details the visual defects observed on the interior surface 5 using an edge masking strip 14 where the geometric shape of the non-contact region 24 (formed by the second portion 24 of the edge masking strip 14) of the edge masking strip 14 provides a tapered surface at different angles as shown in Fig. 6. In the particular examples shown in Fig. 6, the masking strips are composed of Aveolit TA1001 foam (available as above) having a thickness of 1mm and overall width of 8mm. One example of the edge masking strip shown in Fig. 6 has a thickness of 2mm to cater for the larger angle of the tapered edge. The tapered surface of the second portion 24 was made by precision grinding the surface of the edge masking strip as will be discussed in more detail below. According to the observations shown in Table 2, the angle Θ_Β the tapered surface of the second portion 24 makes with the vertical influences the presence of defects such as a prominent paint line and/or overspray on the interior surface 5.

Table 2: Observations on the interior surface of the gap at different angles.

The greater the angle the tapered surface of the second portion 24 makes with the vertical, the wider the open end or mouth 48 of the space 26 that is exposed to the paint spray and, therefore, the more susceptible the interior surface 5 of the substrate 2 adjacent the non-contact region 24 of the edge masking strip 14 is to overspray. Conversely, the smaller the angle Θ_Β the tapered surface of the second portion 24 makes with the vertical, the narrower the mouth or open end 48 of the space 26 that is in line of sight of the paint spray, to the extent that the open end or mouth of the space will function to exclude paint spray from entering this region. This is consistent with the observations made with reference to the gaps formed between the spaced apart metal shims 38 discussed above with reference to Fig. 4. Without wishing to be bound by theory, it is believed that the build-up of air turbulence, and thus the build-up of air pressure in the spaced region 26 bound by the non-contact region 24 of the edge masking strip and the interior surface 5, controls the penetration of paint fluid into the space 26. Little air turbulence is generated around a wide open mouthed space, creating an environment for paint fluid penetration and ingress. The narrower the space 26, the greater the air turbulence and pressure generated. Determining the size of the space 26 so as to function to exclude paint from penetrating this region is dependent upon a number factors including, but not limited to: the air pressure of the paint spray gun; the viscosity of the paint; and the surface and shape characteristics of the interior surface forming the gap 7. The size of the space 26 will be dependent upon what is deemed to be an acceptable paint line finish. However, there will be a saturation point in the size of the space 26, in particular to the width of the space 26 at the mouth 48 of the gap 7, beyond which paint will penetrate or ingress into this region resulting in an unacceptable paint line finish.

Table 2 shows that a tapered angle greater than 8° to the vertical resulted in an undesirable prominent paint line on the interior surface 5 of the substrate 2 on which the edge masking strip 14 is attached. The greater the angle, the higher the number of defects found on the interior surface 5. At angles in the region of 18° - 30°, a band 2-3mm wide of fine overspray resulted on the interior surface 5. Using an 8mm width of edge masking strip 14 and considering that the adhesive region covers approximately 5mm of the width of the edge masking strip 14, the length of the non-contact region 24 forming the tapered surface is thus 3mm. Using simple trigonometry, an angle of 18° will result in an open end or mouth 48 having a width of approximately 1mm (3mm x tan(18°) = 0.97mm). This is in agreement with the observations made with reference to Table 1. Conversely, where the edge masking strip 14 makes an angle less than 8° with the vertical and having an open end or mouth 48 with a width of approximately 0.42mm (3mm x tan(8°) = 0.42mm) resulted in a satisfactory/good paint line finish, i.e. very minute traces of fine over spray.

There are various techniques for configuring the geometric shape of the non-contact region 24 of the edge masking strip 14 adjacent the interior surface 5 to which the edge masking strip is attached as to substantially exclude paint from penetrating this region. These include, but are not limited to: adapting the surface of the edge masking strip 14 by removal of material from the surface of a precursor edge masking strip material (such as to form a tapered surface as described above); and adapting by the addition of material to the surface of a precursor edge masking strip material to space the edge masking strip 14 away from the interior surface 5 of the substrate by means of a spacer 51. The size of the spacer 51 is controlled so as to precisely control the space 26 between the edge masking strip 14 and the interior surface 5 so as to function to substantially exclude paint from penetrating this region. Referring now to Figures 7 a and 7b in some embodiments, at least one channel or recess 1 10 is machined in the surface of a strip of a precursor edge masking strip material 1 17 forming the edge masking strip 14, the recess or channel 1 10 having a precisely controlled angled profile that extends along the length of the masking strip 16 so that the resultant edge masking strip 14 has a tapered edge. The precursor edge masking strip material 1 17 may be a soft, flexible foam material or polymer strip, for example, a polyethylene foam. In one embodiment, the edge masking strip material was based on Aveolit TAl 001 available as above, but other types of soft, flexible foam material or polymer strips that are conformable to the shape of the interior surface 5 of the gap 7 are suitable. There are various methods to precisely machine or cut a channel or recess 1 10 with an angled profile in the precursor edge masking strip material 1 17. These include, but are not limited to: cutting blades, rotary knives, machining (routing), water jet cutting, and laser cutting. Whilst all of these processes are effective to some degree, grinding the surface of the precursor edge masking strip material 1 17 is very effective. The grinding process enables the implementation of a low cost surface machining process to the precursor edge masking strip material 1 17, one which is capable of delivering the precise angle control and clean finish required to form a precisely controlled space effective to exclude paint in the required manner.

To provide the surface of the edge masking strip with a tapered surface or channel having an angled profile, a grinding wheel 60 set at a desired angle 9QR to the horizontal is positioned for relative movement along the length of a strip of the precursor masking strip material 1 17. This enables the grinding of a channel 1 10 with an angled profile that extends longitudinally along the length of the precursor edge masking strip material 1 17 having a controlled depth as shown in the cross-section in Fig. 7a and 7b. Alternatively or in combination to setting the grinding wheel 60 at a desired angle, the precursor edge masking strip material 1 17 could be made to approach the surface of the grinding wheel at a set desired angle.

Grinding can be achieved using several grinding processes including, but not limited to, belt sanders and conventional grinding wheels. In the case of grinding a foam product, the use of a belt carrier wheel 62, 64 in which the belt is a 3M Trizact A160 belt abrasive, available in the UK from 3M United Kingdom pic, 3M Centre, Cain Road, Bracknell, RG12 8HT, has been shown to be effective to grind the surface of the foam material forming the precursor edge masking strip material. The use of an abrasive covered wheel 62, 64 as opposed to a conventional grinding wheel 60 has the advantage that the shape of the grinding surface of the abrasive covered wheel 62, 64 can easily be manipulated simply by controlling the shape of the wheel 68 supporting the abrasive belt 66. For example, a channel with an angled profile having a specified width can be ground in the precursor masking strip material simply by adapting the face 70 of the supporting wheel with an angled edge 9QR and controlling the width of the supporting wheel. Figs. 8a and 8b show two examples where the grinding faces 70 of an abrasive covered wheel 62, 64 that are adapted to have a relatively flat surface (Fig. 8a) or an angled profile (Fig. 8b) respectively. In the particular embodiment shown in Figs. 8a and 8b, the width of the wheel was adapted to grind a channel or recess having a width of approximately 18mm. The angle 0_GR the abrasive face 70 of the grinding wheel shown in Fig. 8b makes with the horizontal is representative of the angle Θ_Β the tapered surface of the edge masking strip 14 makes with the first face. Thus, the greater the angle 0_GR of the grinding face 70 of the abrasive covered wheel 62, 64 makes with the planar surface of the precursor edge masking strip material 117, the greater the angle Θ_Β, of the tapered profile that is ground out of the precursor edge masking strip material 1 17. This enables the application of different shaped channels to be ground out of the precursor edge masking strip material 1 17 that would be difficult to achieve safely on a manufacturing scale using conventional grinding wheels.

The ability to control the topography of the face 70 of an abrasive wheel, in particular the face of the supporting wheel 64, also allows the face of the wheel to be provided with a profile for simultaneously grinding multiple recesses or channels in a strip of the precursor edge masking strip material 1 17, each recess or channel having a desired profiled shape, for example, an angled profile (see Fig. 9). The machining of multiple recesses or channels in the precursor edge masking strip material 1 17 enables multiple masking strips to be manufactured simultaneously in the same manufacturing process. In the particular embodiment shown in Fig. 9, the profile face 70 of the abrasive covered wheel 72 is provided with two angled profiles 74, 76 so that when applied to a strip of the precursor edge masking strip material, the edges of the precursor edge masking strip material 1 17 are ground simultaneously creating a masking strip having a substantially trapezoidal shape as shown in Fig. 10. In the particular embodiment shown in Fig. 9, the angled profile faces 74, 76 make an angle 0_GR of approximately 1 1° with the horizontal. This equates to a taper in the edge masking strip having an angle Θ_Β of approximately 1 1°.

The trapezoidal cross-sectional shape represents two strands of the edge masking strips 1 14a, 1 14b edge-to-edge, which are subsequently separated substantially midway along the length of the precursor edge masking strip material 1 17 as shown by the dashed line in Fig. 10 to create two strands of edge masking strips 14. For example, separation of the precursor edge masking strip to create two edge masking strips can be assisted by the provision of perforations along the length of the precursor edge masking strip shown by the dashed line. In one embodiment, the grinding process was set up by mounting a commercially sourced grinder on a slitter re-winder. However, any suitable electrical or air motor can be used to drive the grinding process. The grinding wheel 72 was positioned over a roller in the web path of a strip of the precursor edge masking strip material 1 17 and the vertical and horizontal position between the surface of the precursor edge masking strip material 1 17 and the grinding face 72 is precisely adjusted for height and angle to give the desired profile cut in the precursor edge masking strip material 1 17. Precision control over the cut depth and angle may be achieved through three dimensional Vernier control positioning of the grinding wheel during process set-up. In this particular embodiment, the Vernier control allows precise control over the x, y, and z coordinates and the angle of the grinding face. In this particular embodiment, angles were set to typically cut a recess or channel in the precursor edge masking strip material having an angled profile Θ_Β between 10° and 20°.

In one example, the precursor masking strip material 1 17, which is typically a foam material, is guided through the appropriate web path past the grinding wheel 72, the precursor masking strip material 1 17 running through the re -winder at a speed of approximately 5 meters/minute. The grinding wheel is operated at an approximate rotational speed of 2950 rpm which equates to a relative abrasive surface speed in the region of 23 ms^"1 for a 150mm diameter wheel. The precursor edge masking strip material 1 17 is then ground out of the foam web to a predetermined depth and angle.

During the grinding process, the texture of the precursor edge masking strip material 1 17, in particular of a foam surface, can be influenced not only by the type of abrasive used but most significantly by the direction of rotation of the grinding wheel relative to the direction of travel of the foam web forming the precursor edge masking strip. When the grinding wheel rotates in the same direction as direction of travel of this foam web, a visually coarser finish is achieved on the ground surface than when the direction of the grinding wheel rotation is opposite to the direction of travel of this foam web. Typical polymeric foam type materials forming the precursor edge masking strip material, due to their inherent manufacturing process, such as extrusion, have a smooth surface or skin. In comparison to a ground surface, the smooth skin has poor absorption characteristics for paint. In order to prevent the accumulation of paint between the edge masking strip and the interior surface of the gap leading to a prominent paint line, the non-contact region 24 of the edge masking strip 14 adjacent the space 26 can be lined with a high absorbency paper so as to wick away any paint contacting the edge masking strip 14. The ground surface of the backing material provides a good key for bonding the paper. However, the process of grinding low surface energy foam produces a coarse surface that may have different liquid absorption characteristics.

As an alternative to an abrasive covered wheel, the grinding surface of a conventional grinding wheel, such as an aluminium oxide wheel, can be shaped with an appropriate profile so as to machine a channel with the desired profile in the precursor edge masking strip material 1 17. The process of grinding foam from a polymeric web can produce a significant amount of dust debris and static charging of the foam web, resulting in the potential for significant dust contamination of the web. To eliminate such dust contamination, de-ionised air and static dissipation systems with vacuum extraction of dust can be employed. Finally, following grinding of the channel or recess in the foam web, the web can be cut lengthwise at the desired width to form the edge masking strip 14 embodying the present invention. Alternatively, instead of machining a shaped profile in the precursor edge masking strip material by means of grinding, the shaped profile can be formed in the precursor edge masking strip material simply by cutting. For example, and as shown in Fig. 1 1 , a strip of the precursor edge masking material 1 17 can be cut lengthwise along a centre line at an appropriate angle to create two edge masking strips, 1 14a, 1 14b, each having a tapered edge formed by cutting along the centre line 78 at a predetermined angle.

Yet alternatively, the edge masking strip 14 can be fabricated by moulding, such as. extrusion or vacuum forming around a suitable mould or pressing a web of thermoformable foam between shaped platens of a hot press. As well as the ability to mould simple geometries such as a tapered edge running along at least one edge of a strip of the precursor edge masking strip material 1 17, more complicated geometric shapes can be moulded than are otherwise possible by means of machining alone. The precursor edge masking strip material 1 17, in the form of a web, can be moulded with multiple profiles wherein at least one face of the edge masking strip 1 16 is divided into two or more portions, each portion being angled with respect to the other. For simple geometries as shown in Fig. 12, the first face 80 of the edge masking strip 1 16 resembles the face profile shown in Fig. 5 providing a tapered edge and thus, is divided into two face portions 122, 124, a first portion 122 and a second portion 124, the first portion 122 of the face 80 being bent at an angle (180 - Θ_Β) with respect to the second portion 124 so as to create a substantially 'V shaped space when cooperating with the interior surface 5 adjacent to the edge of the substrate 2. Thus, as an alternative to machining a tapered edge in a solid edge masking strip or even moulding a solid edge masking strip with a tapered edge, the first 122 and second portions 124 of the web forming the edge masking strip shown in Fig. 12 are bent at an angle. The degree of bending controls the degree to which the non-contact region 124 of the edge masking strip 116 formed by the second portion extends from the interior surface 5.

For more complicated profiles beyond a two portion profile of the kind shown in Fig. 13a, at least one face 180 of the edge masking strip can be divided to form three face portions, 222, 224, 226, a first portion 222, a second portion 224 and a third portion 226 located between the first portion 222 and the second portion 224, each of the face portions being angled with respect to its neighbour. In the particular embodiment shown in Fig. 13a, the first portion 222 is angled at an angle θ_Βι with respect to the third portion 226 (measured from the first face 180 of the edge masking strip) and the third portion 226 is angled at an angle Θ_Β2 with respect to the second portion 224 (measured from the second face 182 opposite the first face 180). The geometric profile of the edge masking strip shown in Fig. 13a is such that when the first portion 222 is provided with a strip of adhesive and is adhered onto the interior surface 5, the apex 82 between the second portion 224 and third portion 226 abuts against the interior surface 5 to cause the second portion 224 to extend from the interior surface 5. This creates a space bounded by the second portion 224 and the interior surface 5. More specifically, during adhesion of the first portion 222 to the interior surface 5, a portion of the non- adhesive region of the first portion 222 and the third portion 226 can flex as a result of the apex 82 between the second portion 224 and third portion 226 butting up and pushing against the interior surface 5. The width of the space is determined by the angle θ_Βι formed between the first portion 222 and the third portion 226 and/or the angle Θ_Β2 between the second portion 224 and/or the third portion 226, as well as the resiliency of the material forming the edge masking strip. The smaller the angle Θ_Β2 the second portion makes with the third portion 226, the more the second portion 224 extends from away of the interior surface 5 when the edge masking strip 1 16 is attached to the mounting surface of the substrate, and thus, the wider the space. The smaller the angle θ_Βι between the first portion 222 and the third portion 226, the further away the second portion 224 extends from the interior surface 5 when offered up prior to adhesion of the first portion, and thus the wider the space bounded by the second portion 224 and the interior surface 5 after adhesion of the first portion 222. By controlling the angle(s), ΘΒΙ, Θ_Β2, and the material resiliency independently or together, the size of the space 26 can be varied (see Fig. 13c). Alternatively, instead of the third portion 226 being a substantially straight portion as shown in Fig. 13 a, the third portion 226 can be a substantially curved as shown in Fig. 13b. The width of the spaced region 26 bounded by the non-contact region of the edge masking strip 1 16 and the interior surface 5 is determined by the degree of curvature and/or length of the third portion 226, 326.

The thickness of the edge masking strip aids in determining the size of the space bounded by the non-contact region of the edge masking strip 216 and the interior surface 5. As demonstrated in Fig. 13c, by coating the part of the first portion 222 with an adhesive strip 23, the region of the first portion 222 where there is no adhesive flexes or provides a hinge point. The apex 82 of the edge masking strip 1 16 between the second portion 224 and the third portion 326 abuts and pushes against the interior surface 5 of the gap 7. The degree of this flexibility of the precursor edge masking strip material 1 17 including the compressibility of the apex portion controls the degree which the second portion 224 extends away from the interior surface 5. Too thick a material will inhibit any flexing of the region of the precursor edge masking strip material 1 17 where there is no adhesive, in particular the region between the first portion 222 and the third portion, at a hinge point 82. More importantly, the thicker the precursor edge masking strip material 1 17 used, the lesser the ability of the edge masking strip 1 16 to replicate the shape of the mould, in particular the finer detail of the mould, for example, the varying contour profile of the mould face. In one particular embodiment, a 1.0 mm thick polyethylene foam Aveolit TA1001 , available as above, was used. However, other types of mouldable materials are suitable for use in the present invention so as to allow the edge masking strip 1 16 to conform easily to the shape of the interior surface 5 adjacent to the substrate 2.

To improve efficiency in the fabrication of the edge masking strip of the present invention, the edge masking strip 1 16, 216 can be moulded simultaneously in a one-step operation with two edge masking strips, 1 16a, 216a, 1 16b, 216b connected edge-to-edge as shown in Fig. 14(a and b). In this situation, opposite portions of a precursor edge masking strip material 1 17 are moulded with space defining features (e.g. varying face profiles), each space defining feature representing one edge masking strip 1 16a, 216a, 1 16b, 216b as discussed above with reference to Fig. 12 and Fig. 13. The moulded precursor edge masking strip material 1 17 is subsequently separated substantially along a centre line located substantially midway across the width of the moulded precursor edge masking strip material 1 17 along the length of the strip as shown by the dashed line in Fig. 14 (a and b), to create two lengths of the edge masking strip 1 16a, 216a, 1 16b, 216b.

Masking Strip - Edge Masking Strip and Gap Filler

To prevent paint from penetrating into the region of a gap 7 formed between two substrates 2, 3 to be painted, a gap filler 28 can be fixed to the edge masking strip such that the edge masking strip 14 forms a backing of the masking strip 16. The masking strip 16 therefore comprises a gap filler 28 and the edge masking strip 14 described above. The gap filler 28 extends at an angle Θ₀ΑΡ from the second face 20 of the edge masking strip facing towards the gap 1 to mask the region of the gap 1 between the two substrates 2, 3 to be painted (see Fig. 3). Ideally, when not in use, the angle ΘΟΑΡ the gap filler 28 makes with the second face 20 of the edge masking strip 14 is less than 90° (as measured between the gap filler 28 and the second face 20 of the edge masking strip distal from where they are bonded together). In use, when the edge masking strip 14 is attached to a first interior surface 5 of the gap 1 , the distal end 29b of the gap filler 28 furthest away from the point of connection with the edge masking strip 14 locates itself below the paint line, PL_m. This is in the unexposed region of the moveable substrate 3 such that there is no contact between the gap filler 28 and a portion of the interior surface 6 of the gap at or in the region of the paint line, PL_m. The simplest approach is to separately attach or bond or crimp the gap filler 28 to the second face 20 of the edge masking strip 14 either before or following attachment of the edge masking strip 14 to the interior surface 5. For ease of explanation, the edge masking strip 14 has a first face 18 and an opposite second face 20. An adhesive region 22 extends along a portion of the first face 18 of the edge masking strip 14 and the gap filler 28 extends from the second face 20 of the edge masking strip 14. However, other means to fix the gap filler 28 to the edge masking strip 14 may be used, such as double sided adhesive tape, application of hot melt adhesive or ultrasonic welding. In this particular embodiment, the gap filler 28 is composed of a polyurethane foam. An example of polyurethane foam that can be used in the present invention is X4200am polyurethane foam sourced from Caligen Foam LTD, as above. Equally, a number of other foams or non-foamed polymeric materials including woven and non-woven fabrics are suitable for use in the fabrication of the gap filler 28.

The gap filler 28 and the edge masking strip 14 of the present invention are preferably fabricated together as a preformed masking strip 16. The advantage of fabricating the masking strip 16 comprising the edge masking strip 14 and gap filler 28 as a preformed product removes the inconvenience of having to separately attach the edge masking strip 14 and then the gap filler 28 to the interior surface 5 of the gap 1.

The machining process discussed above with reference to the precursor edge masking strip material 1 17 could also be employed to machine a recess of a predetermined profile in a strip of a precursor gap filler material 128a, for forming the gap filler 28. In this particular embodiment, the precursor gap filler material forming the gap filler 128, 228 in Fig. 15 and 16, comprises a strip of polyurethane foam. At least one end or edge of the strip of precursor gap filler material 128a, 228a is machined to form a profile 90, 190 extending along the length of the strip such that when the machined profiled end is attached or bonded to the second face 20 of the edge masking strip 14 as shown in Figs. 15b and 16b, the shape of the profile 90, 190 causes the remainder 129, 229 of the strip of precursor gap filler material 128a, 228a to extend away from the edge masking strip 14 at an angle ΘΟΑΡ· Figs. 15(a and b) and Fig. 16(a and b) demonstrate two examples where the profile of the recess machined at one end of the strip of foam material used as the precursor gap filler material 128a, 228a is stepped 90 or angled 190 so as to cause the precursor gap filler material 128a, 228a to extend at an angle from the edge masking strip 14 when bonded or otherwise secured thereto.

In Fig. 15(a and b), a semi-rectangular recessed profile 90 is machined at one end of a strip of foam material forming the precursor gap filler material 128a. The step change in the gap filler thickness at point X encourages the remainder 129 of the gap filler 128 to extend outwards at an angle from the edge masking strip 14. Alternatively, the gap filler 228 is encouraged to extend from the second face 20 of the edge masking strip 14 at an angle by machining a tapered surface or angle profile 190 at one end of the gap filler 228 (see Fig. 16(a and b)). The degree of extension from the second face 20 of the edge masking strip 14 is determined by the angle the taper makes with the width of the gap filler 228. Bonding of the precursor gap filler material 128a, 228a to the second face 20 of the edge masking strip 14 can be by any means, including, but not limited to: double side adhesive tape, hot melt adhesive, welding, crimping or sewing. As shown in Fig. 17, the gap filler 328 can be formed by inwardly folding lengthwise one edge of a strip of a precursor gap filler material 98 in two onto a strip of adhesive 96 extending along the length of the precursor gap filler material 98 so that the folded edges 92, 93 are out of register. The folded edge 92 of the gap filler is close or proximal to the second surface 20 of the edge masking strip 14 (where the first surface 18 of the edge masking strip 14 comprises the adhesive region 22 for attachment onto the mounting surface adjacent to the edge of the substrate surface to be painted). The edge 92 of the gap filler is folded over in two such that it adheres to the edge of the adhesive strip 94 leaving an exposed portion 96 of the adhesive strip 94 for subsequent attachment to the edge masking strip 14 (see Fig. 17). By folding and bonding lengthwise one edge of a strip of the precursor gap filler material 98 such that the edge of the precursor gap filler 98 is bonded to one edge of the adhesive strip 94, the resultant gap filler 328 is formed into a loop as the adhesive does not extend across the whole of the interior facing portion of the folded strip of precursor gap filler material 98. Equally, it is possible to provide the gap filler 328 with an adhesive surface such that when folded both folded portions adheres to themselves over the entire folded interface.

For continuous mass manufacture, the folding operation can be performed by drawing a strip or web of the precursor gap filler material from a roll via a series of rollers to a station comprising a folding device to fold lengthwise in two at least one edge of the precursor gap filler material. For example, the folding device can be based on the arrangement described and shown in WO83/04380. Securing the folded edge of the web can be accomplished by passing the folded region through a pair of nip rollers. Further details of a process for manufacturing a continuous masking strip of the present invention are discussed below. Conveniently two masking strips can be fabricated simultaneously, each masking strip resembling the masking strip shown in Fig. 17. Fig. 18 (a to h) shows the series of steps involved. In step 1 as shown in Fig. 18a, a strip/web of polyurethane foam material 100 of a suitable thickness is cut to a suitable width. As discussed with reference to Fig. 17, the gap filler can be composed of polyurethane foam, e.g. X4200am polyurethane foam available from Caligen Foam LTD as above. In this particular embodiment, a strip of polyurethane foam having a thickness in the range 3mm to 4mm is cut to a width of approximately 54mm. In step 2 as shown in Fig. 18b, one face 102 of the strip/length of the precursor gap filler material is coated along the middle with a strip of adhesive 104. In the particular embodiment shown in Fig. 18b, the strip of adhesive 104 has a width, D, of approximately 12mm. Various techniques to coat the foam strip with the adhesive strip can be used. These include, but are not limited to: the application of double sided adhesive tape, hot melt adhesive or other bonding agents commonly known in the art. In step 3 as shown in Fig. 18c, the longitudinal edges 107a, 107b of the gap filler material are folded upwards and inwards. In step 4 as shown in Fig. 18d, the longitudinal edges 107a, 107b of the gap filler material 100 are folded in two (as indicated by the arrows) in such a manner that they are adhered or bonded to the edges of the adhesive 104 leaving a central portion 108 of the adhesive exposed. Between the folded edges of the precursor gap filler material, a recess or channel 210 is formed having a substantially rectangular cross-section and extending centrally along the length of the precursor gap filler material, the base of the recess or channel comprising the exposed adhesive portion 108. In the particular embodiment shown in Fig. 18d, the folded ends are bonded to the adhesive portion leaving an exposed adhesive region 108 of approximately 6mm in width. Each of the two folded ends 107a, 107b of the precursor gap filler material either side of the recess or channel 210 represent two gap fillers edge- to-edge as will be made clear below. In the particular embodiment shown in Fig. 18d, for efficiency a portion of the precursor gap filler sheet material is coated with a relatively narrow strip of adhesive such that the edges of the precursor gap filler material adhere to the edges of the adhesive, and thus, each gap filler is folded into a loop. Alternatively, the entire face of the precursor gap filler material at the interface between the folded portions 107a, 107b can be coated with an adhesive so permitting the folded edges to adhere entirely onto the adhesive region without forming the precursor gap filler material into a loop.

The folding of the ends of the precursor gap filler material onto a strip of adhesive can be achieved in an automated process by drawing a strip of the precursor gap filler material 100 into a processing station comprising a folding or gathering device 1 12 as shown in Figs. 21 to 23. This takes the strip of the precursor gap filler material 100 at Section Y-Y of Fig. 22-23 and folds the edges of the foam around the adhesive region as shown at Section X-X of Fig. 22-23 by virtue of the narrowing of the passageway through the gathering device. One example of a gathering or folding device 1 12 having a passageway whose width narrows along the length of the gathering or folding device is a cone shaped device 1 12 as shown in Fig. 21. This has an entrance 1 14 with a width that is greater than the width of the strip of the precursor gap filler material and an exit orifice having a width that is smaller than the unfolded width of the strip of precursor gap filler material but substantially equal to the folded width. Fig. 24a and Fig. 24b shows a cross-section along the sections X-X and Y-Y of Fig. 22-23 respectively, showing the stages of the precursor gap filler material at the entrance 1 14 of the gathering or folding device and when folded at the exit of the gathering or folding device. The folded strip of the precursor gap filler material is then passed through a pair of nip rollers 121 as shown in Figs. 22-23 which pressure set the folded edges 107a, 107b onto the edge of the adhesive region 104 leaving an exposed region 108 of adhesive. Alternatively, a separate strip of adhesive positioned substantially centrally and along the length of the precursor gap filler material can be drawn together with the precursor gap filler material through the gathering or folding device, such that the folded portions of the precursor gap filler material are pressed or laminated together through the gathering or folding device. Other bonding techniques known in the art are also suitable. These include, but are not limited to, drawing the folded strip of gap filler material through a pair of heated nip roller(s) to partially melt and bond the folded edges of the precursor gap filler material. Other techniques include having a separate station for applying hot melt adhesive to the gap filler material prior to being drawn through the gathering or folding device.

In step 5 as shown in Fig. 18e, a strip of the precursor edge masking strip material 1 17 whereby two edge masking strips are joined back-to-back is adhered to the exposed adhesive region 108 of the folded foam material to form an assembled strip. When joined to the precursor gap filler material, each of the edge masking strips forms a backing to the gap filler. In the particular embodiment shown in Fig. 18e, the strip of precursor edge masking strip material has a substantially trapezoidal cross-section as discussed above such that when cut substantially down the middle yields two edge masking strips. However, the strip of the precursor edge masking strip material is not restricted to the substantially trapezoidal shape as shown in Fig, 10 and 18e, but other (parabolic) shapes or profiles are permissible so as to exclude paint from penetrating into the space bounded by the surface adjacent to the substrate to be painted and the non-contact region of the edge masking strip 14. One example is the precursor edge masking strip material 1 17 discussed above with reference to Fig. 14(a and b) having multiple portions, each portion being angled (bent) with respect to its neighbour.

Various techniques can be used to fabricate the precursor edge masking strip material 1 17. These include, but are not limited to: grinding, cutting, extrusion or moulding as discussed above. The strip of the precursor edge masking strip material is orientated on the exposed adhesive region 108 of the precursor gap filler material 100 such that the first face 18 of the precursor edge masking strip material 1 17 responsible for creating the paint excluding space is furthest away from the exposed adhesive region 108. In the particular embodiment shown in Fig. 18e, the first face 18 of the edge masking strip comprises tapered ends and is furthest away from the exposed adhesive region 108 of the gap filler. The second face 20 of the edge masking strip lies nearest to the exposed adhesive region 108 of the gap filler. At this stage, the degree to which the folded gap filler material extends away from the precursor edge masking strip material is dependent upon the thickness of the foam material and the distance between the folded edges. The recess or channel 210 formed in the precursor gap filler material 100, as a result of the folded edges 107a, 107b of the precursor gap filler material 100, cooperates with the second face 20 of the precursor edge masking strip material to create a space 1 1 1. The depth of this space 1 1 1 is determined by the thickness of the precursor gap filler material. In step 6, as shown in Fig. 18f, the face 20 of the precursor edge masking strip material 1 17 is adhered to the exposed adhesive region, for example, by the application of pressure (Step 7 in Fig. 18g). Due to the thickness and resiliency of the precursor gap filler material, the folded regions 107a, 107b are caused to extend away from the precursor edge masking strip material 1 17 at an angle so as to adopt a substantially 'K' shaped configuration (see Fig. 18h). The thicker the precursor gap filler material and the wider/deeper the space 1 1 1 (not shown in Fig. 18h), the more the folded edges of the precursor gap material are forced to extend away from the precursor edge masking strip material as the precursor edge masking strip material is stuck to the exposed adhesive 108. The folded foam 107a, 107b of the precursor gap filler material 100 hinges itself from the face 20 of the edge masking strip 14 due to the folded return of the folded edges. This creates a pressure point due to a differential in thicknesses of the precursor gap filler material 100. However, a point will be reached in the thickness of the precursor gap filler material 100 whereby the thickness becomes too great to facilitate any controllable folding of the edges of the strip of precursor gap filler material.

The assembled precursor gap filler material 100 and the precursor edge masking strip material 1 17 form two masking strips 14a, 14b joined edge-to-edge. In step 8 as shown in Fig. 18(h), the assembly is cut substantially centrally along a centre line for its length to yield two separate and complete masking strips 16, the precursor edge masking strip material forming the edge masking strip of the completed masking strip. A strip of adhesive 23 responsible for enabling the edge masking strip to be attached to the interior surface of the gap between two substrates is applied onto a portion of the first face 18 of the edge masking strip 14. The strip of adhesive can be applied during any of the steps 5 to 8 discussed above or can pre-applied to the edge masking strip 14 prior to step 5. Anoptional liner (not shown) may also be applied.

The same principle method with reference to Fig. 18(a to h) can also be applied for simultaneously fabricating two masking strips edge-to-edge, each masking strip resembling the masking strip shown in Figs. 15 and 16. Instead of folding the edges of the precursor gap filler material to create a profile shaped with a recess or channel substantially disposed centrally along the length of the precursor gap filler material, a recess or channel 90, 190, having either a rectangular cross-section 90 or a 'substantially 'V shaped 190 can be machined (e.g. by grinding as discussed above) into the precursor gap filler material 100 of sufficient thickness substantially centrally along its length as shown in Figs. 19 and 20. The two gap fillers 328a, b 428a, b are located either side of the machined channel or recess 90, 190. As described with reference to Fig. 15(a and b) and Fig. 16(a and b), the rectangular machined profile or the angle machined profile cooperates with the second surface of the precursor edge masking strip to create a space which when bonded to the precursor edge masking strip material causes the gap filler material either side of the machined channel to extend away from the precursor edge masking strip material at an angle and adopt a 'K' shaped configuration (similar to the configuration shown in Fig. 18h). The extent of this deformation is again dictated by the dimensions of the profile, similarly to the folded precursor gap filler material described above with reference to Fig. 18(a to h). Bonding the precursor gap filler material to the precursor edge masking strip material, more specifically to the second face 20 of the edge masking strip 14, can be achieved by coating a portion of the base of the recess or channel 90, 190 with adhesive or alternatively by suitably welding the base of the recess or channel to the precursor edge masking strip material. Finally, the assembled precursor gap filler material and precursor edge masking strip material is cut substantially centrally along a centre line for its length to yield two separate and complete masking strips, each completed masking strip comprising an edge masking strip represented by the cut precursor edge masking strip and a gap filler. Further details of the arrangement of processing stations for the mass manufacture of the masking strip of Fig. 18 are discussed below with reference to Fig. 31. Instead of separately fabricating the edge masking strip and the gap filler and then assembling them together as discussed above, the edge masking strip and the gap filler can be integrally formed as a single body. A sheet of thermoformable material can be thermoformed around a mould, the mould being shaped to form a single body comprising the gap filler and edge masking strip extending from it, such that the gap filler and the edge masking strip are composed of the same material. In this particular embodiment, the material used in moulding the masking strip is a polyethylene cross linked foam, Aveolit TA1001, available from Sekisui Alveo AG, as above. As the degree of detail that is replicated from the mould is dependent upon the thickness of the thermoformable sheet material, this thickness is chosen to ensure maximum detail is replicated from the mould but yet the thermoformed sheet has sufficient rigidity to function as a masking strip, such that the gap filler extends from the edge masking strip without collapsing. The sheet of thermoformable material used in the particular embodiment has a thickness of about 1.0mm, although other thicknesses can be used.

The mould is shaped so that the moulded product comprises a gap filler that extends from a backing (which acts as an edge masking strip). The gap filler is adapted to prevent paint from penetrating a gap between two substrates and the edge masking strip being adapted to cooperate with an interior surface of the gap to create a space that substantially excludes paint penetration. In this particular embodiment, the thermoformable sheet material is vacuum formed around a shaped mould 420 having a substantially triangular or 'V cross-section having a first forming face 422 for shaping the edge masking strip and a second forming face 424 for shaping the gap filler (see Fig. 25), separated by an angle Θ_Μ· Thus, the resultant vacuum formed masking strip 216 shown in Fig. 30a, b is shaped with a first leg 126 that forms the edge masking strip 214 (replicating the first forming face 422 of the mould 420) and a second leg 128 (replicating the second forming face 424 of the mould 420) that forms the gap filler 328. The second leg 128 is formed at an angle θ_ν with respect to the first leg 126. The angle Θ_Μ between the first forming face 422 and the second forming face 424 of the mould 420 determines the angle θ_ν between the moulded first 126 and second 128 legs of the vacuum- formed masking strip 216, which in turn controls the degree by which the gap filler 328 extends from the edge masking strip 214 in the moulded masking strip 216.

The first forming face 422 of the mould is contoured such that, in use, the profile of the moulded first leg 126 of the masking strip enables a portion 224 of the first leg 126 (non-contacting region) to cooperate with the interior surface of the gap to create a space. This space is sized to exclude paint from penetrating into this region. The simplest approach would be to include a tapered or other shaped portion on the edge masking strip by contouring the first forming face of the mould with two face portions. Thus, the moulded first leg is profiled with two portions as discussed with reference to Fig. 13b to make a first portion and a second portion on the first face of the edge masking strip 14, the first portion being angled with respect to the second portion. This results in the edge masking strip having a similar profile to that shown in Fig. 13b. The first portion is provided with a strip of adhesive so that when the first portion is adhered to an interior surface of a gap, the second portion extends from the interior surface of the gap to create a substantially triangular or 'V shaped space bounded by the second portion and the interior surface of the gap. The angle is created by the presence of a third portion positioned between the first portion and the second portion. This in turn dictates the width of the space bounded by the second portion and the interior surface of the gap. The first forming face 422 of the mould may have alternative profiles so that, in use, the profile of the first leg creates a space between the non-contact region of the edge masking strip and the interior surface of the gap, the size of the space functioning to exclude paint from travelling into the space. In the particular embodiment shown in Figs. 25 and 26a, 26b, the first forming face 422 of the mould is contoured with three face portions, 422a, 422b, 422c so that the profile of the moulded first leg 126 forming the edge masking strip replicates the three face portions as shown and discussed above with reference to Fig. 12, 13(a and c), each face portion being angled with respect to its neighbour.

As shown in Fig. 25, each face of the mould is stepped to form a demarcation region for separating the trim or waste from the vacuum moulded masking strip. The choice of material of the mould/tool 420 is dependent upon its ability to be machined to form the different profiles in each face of the mould. The mould in this particular embodiment was fabricated from brass material. However, other easily machineable materials can be used to form the mould, such as aluminium. Vacuum holes 423 are drilled at regular positions along the length and width of the mould 420. This ensures that the foam sheet material is drawn onto the mould, particularly in the region around the sharp detail of the profile so as to replicate the finer detail on the mould face, for example, the angled profile of each face of the mould. The underside of the mould is formed with a cavity through which the vacuum drilled holes are connected to a source of vacuum, for example, a vacuum pump, by means of suitable pipework (see Fig. 26b).

Various techniques for vacuum forming a sheet of thermoformable foam material around a precisely shaped mould can be used. Moreover, no vacuum holes are necessary in the mould in the case of thermoforming the material around the mould. However, the vacuum holes help to enhance the replication of the detail from the mould. As shown in Fig. 27 at stage 1, a blank section of thermoformable material 200 is cut to size to fit the thermoforming machine aperture 202 and clamped in place. At stage 2 as shown in Fig. 28, the thermoformable sheet is heated to a temperature so that the intricate details or profiles are replicated from each face of the mould when the sheet material is vacuum drawn onto the mould face. A sliding cover containing ceramic heaters is moved completely over the clamped foam to heat the foam surface to a temperature of around 1 10°C. In practice this takes about 25 seconds. When the surface of the foam sheet has reached 1 10°C, the mould which is located below the foam sheet is brought up to make contact with the foam sheet and at the same time the vacuum pump is activated for a predetermined length of time (with the resultant vacuum indicated by arrows V). At stage 3 as shown in Fig. 29, whilst under vacuum the ceramic heaters are moved away from the foam and the softened sheet foam is drawn onto and into the detailed profiles of the mould. A portion of the sheet of foam then takes the shape of the mould, in particular the contours of the mould face. At stage 4, the moulded sheet material is then allowed to cool for a predetermined length of time, following which the vacuum pump is switched off and the moulded sheet is withdrawn from the mould. Fig. 30a and 30b show a top view and a cross-sectional view of the moulded sheet foam wherein the profile of the mould face 422, 424 is replicated in the foam. At stage 5, the trim is removed from the moulded foam by cutting the thermoformable material along the dashed lines 130 shown in Fig. 30b. As can be seen in Fig. 30b, the first leg representing the edge masking strip has three portions 222, 224, 326 representing the edge masking strip profile discussed above with reference to Fig. 13b. The portions of the leg are angled with respect to each other to create a critical profile forming an apex 82 in the face of the edge masking strip so that, in use, the non-contact region of the edge masking strip cooperates with the surface adjacent to the edge of the substrate to be painted and forming part of the interior surface of the gap to create a space sized so as to exclude paint. In the particular embodiment shown in Fig. 30b, the third portion 326 of the first face of the edge masking strip 214 is curved as shown and described with reference to Fig. 13c. The degree of curvature influences the degree by which the non-contact region of the edge masking strip extends from the interior surface of the gap to which the masking strip is attached. A strip of adhesive coating is applied to the edge masking strip first leg portion 222 (first portion), e.g. a hot melt adhesive or double sided sticky tape. The adhesive coating can be applied during any of the stages 1 to 5. However, it is easier to apply the adhesive to the first portion region of the edge masking strip whilst the thermoformable material is still located on the mould in stage 4 since the mould surface provides a support for the application of the adhesive to the first portion.

The length of the vacuum moulded masking strip is limited by the length of the tool. By indexing the strip along the length of the tool, a continuous length of masking strip can be moulded. Once a first portion of the thermoformable sheet is moulded around the tool, the sheet of thermoformable material is moved longitudinally along the tool by a predetermined length so that a blank portion of the same thermoformable sheet material is adjacent the tool and the process of vacuum forming a second portion of blank sheet around the tool is repeated as discussed with reference to Figs. 25 to 28 (stages 1 to 5). This is repeated along the length of the sheet material so as to provide a continuous strip of masking strip. To achieve a seamless joint between adjacent moulded portions, the sheet of material is not moved all the way across the length of the tool until a fresh length of blank sheet is adjacent the tool but rather a slightly shorter distance so as to permit overlapping of adjacent moulded portions of the masking strip at their ends. More specifically, the trailing edge of a first moulded masking strip overlaps the leading edge of a neighbouring second moulded masking strip. Obviously, the number of repeats and the overall length of the masking strip will be dependent on the length of the tooling used. The longer the tool, the less repeats are required to achieve the same length of masking strip than if the tooling was shorter. Finally the trim is removed from the moulded masking strip.

The process of vacuum forming a sheet of thermoformable material around a shaped tool by indexing along the length of the tool so as to produce a continuous length of moulded strip is not restricted to masking strips for vehicles and can be used in other applications as an alternative to extruding. For example, the same indexing process can be used in fabricating draft excluders or seals for doors and windows. Details and contour profiles that cannot be easily reproduced by extruding alone can be produced by vacuum forming techniques described above. Equally, vacuum forming techniques can be applied to materials that cannot easily be extruded due to their inherent material properties or chemistry. In some embodiments and as a precautionary measure, for example, during heavy application of paint spray, the surface of the non-contacting region of the edge masking strip can be formed to absorb paint, so that it draws paint away from a proximal surface of a part of the vehicle body. For example, the non-contacting region of the edge masking strip proximal to the interior surface of the gap can be lined or coated with paper having a high paint absorbency, e.g. Neenah Gessner raw 39gsm GP paper, available from Neenah Gessner GmbH, Otto-von-Steinbeisstr. 14b, 83052 Bruckmuhl, Germany.

It will be appreciated that any suitable thermoformable foams could be used to produce the edge masking strip and/or the gap filler of the masking strip of the present invention. Suitable materials can be found not only among polyethylene foams but also among, for example, polyester, polystyrene, polyvinylchloride, polyethylene and polypropylene foams. The foam can be open cell or closed cell provided it is sufficiently resiliently compressible for conforming to a required shape for a given application.

Industrial Process

Fig. 31 is a diagram illustrating the processing stations that may be used in the mass manufacture of masking strip, as described with reference to Figs. 17 to 20. Starting at the top right hand corner of Fig. 31 and following the arrows, precursor edge masking strip material 517 forming the edge masking strip of the masking strip in the form of a polymeric foam is fed from a supply roll via a take-up roll 518 to Station 1 (519). In this particular embodiment, the precursor edge masking strip material on roll 517 is interleaved with a protective or release paper supply roll which is taken up by the roll 518 as it is fed to Station 1 (519). Station 1 is responsible for the application of the pressure sensitive adhesive to a portion of the precursor edge masking strip material. The pressure sensitive adhesive on the edge masking strip should be capable of adhering the masking strip of the present invention to the interior surface of the gap between two substrates, in the case of vehicle to the bodywork of the vehicle, e.g. the static part. When the masking strip is packaged in the form of a roll, the surface of the masking strip opposite the adhesive region of the backing may be coated with a release material or release liner to prevent the adhesive region of the backing in one layer of the roll adhering to the masking strip in an adjacent layer of the roll. Any suitable release material may be used for this purpose. In the particular embodiment shown in Fig. 31, the pressure sensitive adhesive is supplied from a roll 520 of adhesive strip on a release liner. The combination of the adhesive strip and the backing material forming the edge masking strip are laminated together by feeding through a pair of nip rollers 522. Whatever form of adhesive is used, it should permit flexing of the masking strip whilst being secure enough, when the masking strip is used to mask the gap between a static part and a moveable part 3 or between two moveable parts 3 of a vehicle, to withstand the pressure wave created by closing a moveable part 3 of the vehicle onto it. The attachment means should also be able to withstand any post-treatment of the applied paint (e.g. baking). To improve the adhesion between the adhesive layer and the backing material, the backing material can optionally be corona treated at a suitable treatment station 521 prior to the application of the pressure sensitive adhesive onto the precursor edge masking strip material in Station 1 (519).

The precursor edge masking strip material that leaves Station 1 (519) comprises a strip of adhesive coated with a release liner. Following treatment of the precursor edge masking strip material in Station 1 , the precursor edge masking strip material then travels to the grinding operation at Station 2 (523). The grinding operation at Station 2 grinds at least one edge of the precursor edge masking strip material to create at least one chamfered edge as described above with reference to Fig. 7 to 10. In the particular embodiment shown in Fig. 31 and to improve efficiency of manufacture, the grinding operation involves grinding lengthwise both edges of the precursor masking strip material so that the cross-section of the strip of precursor masking strip material has a substantially trapezoidal shape as shown in Fig. 10. Any excessive trim is also removed from the ground/machined precursor edge masking strip material and fed onto a roll 524 for possible recycling.

An additional station may be optionally added after the grinding operation to laminate the tapered edge of the precursor edge masking strip material with high absorbency paper or paint. However, this may not be necessary since the ground surface of the precursor edge masking strip material may have improved paint absorbent characteristics. Following grinding a tapered edge to at least one edge of the precursor edge masking strip material, the treated precursor edge masking strip material is at a stage for fixing onto the precursor gap filler material to complete the masking strip. Below the supply roll of the precursor edge masking strip material is a supply roll 525 of the precursor gap filler material. It will be appreciated that any suitable thermoformable foams could be used to produce the backing forming the edge masking strip and/or the gap filler of the masking strip of the present invention. Suitable materials can be found not only among polyethylene foams but also among, for example, polyester, polystyrene, polyvinylchloride, polyethylene and polypropylene foams. The foam can be open cell or closed cell provided it is sufficiently resiliently compressible for conforming to a required shape for a given application.

The precursor gap filler material in the form of a polymeric foam is fed from the supply roll into Station 3 526 responsible for grinding a channel or recess having a substantially rectangular or angled profile substantially centrally and along the length of the strip of precursor gap filler material so as to create two gap fillers either side of the recess or channel as discussed above with reference to Fig. 19 and 20. Following grinding a channel or recess in the precursor gap filler material, the machined precursor gap filler material is fed via a series of rollers to Station 4 (527) responsible for the application of adhesive in the machined channel or recess of the precursor gap filler material. As discussed with reference to Fig. 18e, the precursor gap filler material following the machining step in Station 4 is brought together with the treated precursor edge masking strip material by passing through a pair of nip rollers 528 to encourage the machined recess or channel in the precursor gap filler material to bond to the edge masking strip material. As a result of the bonding, the precursor gap filler material either side of the machined channel or recess is encouraged to extend from the face of the precursor edge masking strip material and adopt a substantially 'K' type configuration comprising two masking strips edge-to-edge as discussed above. Finally at Station 5 (529), the assembled/laminated precursor gap filler material and the precursor edge masking strip material is cut to generate two masking strips, each masking strip comprising an edge masking strip and a gap filler extending from the edge masking strip. Two master roll winders 530a, 530b pick up the completed masking strips as continuous rolls. To cater for the fabrication of the masking strip whereby the edges of the precursor gap filler material are folded inwardly in two so forming a recess or channel in the folded precursor gap filler material as described with reference to Fig. 18(a to h), the processing stations shown in Fig. 31 is adapted by replacing the grinding station 526 with an adhesive station and the adhesive station 527 with a folding or gathering station. Instead of machining a recess or channel in the precursor gap filler material and subsequently bonding the machined precursor gap filler material to the precursor edge masking strip material so as to adopt a substantially 'K' shaped configuration, the recess or channel is formed in the precursor gap filler material by feeding a strip of the precursor gap filler material coated with an adhesive strip into a folding or gathering station. A typical folding or gathering station is described above with reference to Figs. 21 to 24. However, other folding devices that are capable of folding the ends inwardly in two along the length of the precursor gap filler material can be used. The remaining processing stations responsible for treating the precursor edge masking strip material, for example, cutting the assembled strip and rolling up the finished masking strips are the same as discussed with reference to Fig. 31. It will be appreciated that the different combinations of the processes and features discussed above can be used interchangeably to fabricate the masking strip of the present invention. For example, the moulding and machining process described above can be used interchangeably in any suitable combination to fabricate the edge masking strip and/or gap filler of the present invention.

Claims

1. A method of making an edge masking strip for masking an edge of a substrate to be painted, comprising the steps of:

i) providing a precursor edge masking strip material;

2. The method as claimed in claim 1, wherein the step of removing material comprises the step of machining a channel or recess in the precursor edge masking strip material, said channel or recess having a cross-section with a substantially angled profile.

3. The method as claimed in claim 1, wherein the step of removing material comprises the step of grinding a channel or recess in the precursor edge masking strip material, said channel or recess having a cross-section with a substantially angled profile.

4. A method of making a masking strip for masking an interior surface of a gap between a first substrate and a second substrate positioned adjacent the first substrate, comprising the steps of: i) providing a precursor edge masking strip material;

iii) providing a precursor gap filler material;

5. The method as claimed in claim 4, wherein the profile is one of: substantially rectangular, substantially angled, substantially curved or a channel or recess.

6. The method of claim 4, wherein the step of forming a profile comprises the step of forming a channel or recess in the precursor gap filler material by folding the precursor gap filler material inwardly in two and securing opposed portions of the precursor gap filler material along its length such that the channel or recess lies adjacent to the folded portions of the precursor gap filler material.

7. The method of claim 6, further comprising the steps of;

8. The method as claimed in any of the claims 4 to 7, wherein the step of securing the precursor gap filler material to the precursor edge masking strip material comprises the steps of a) applying an adhesive strip to the precursor gap filler material; and

b) adhering the precursor gap filler material to the precursor edge masking strip material.

9. The method of claim 8, wherein said at least one folded portion of the precursor gap filler material is adhered to the adhesive strip so as to leave a width of exposed adhesive strip adjacent the folded portion of the precursor gap filler material.

10. The method of claim 4, further comprising the steps of:

1 1. A method of forming a masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, comprising:

12. The method of claim 1 1, wherein the masking strip is formed by moulding or extruding.

13. The method of claim 1 1 or 12, further comprising the step of thermoforming the precursor masking strip material around at least one shaped mould, wherein the shaped mould has a first forming face representing the edge masking strip and a second forming face representing the gap filler such that the resultant thermoformed masking strip is shaped with a first leg forming the edge masking strip and a second leg forming the gap filler.

14. The method of claim 13, wherein the shaped mould has a substantially triangular cross section.

15. A method of forming a continuous profile of a predetermined shape extending along a strip of a formable material, comprising the steps of;

i) thermoforming the material against at least one shaped mould to form a strip of profiled material; and

16. The method of claim 15, wherein the continuous profile is a masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, the masking strip comprising an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip.

17. The method of any of claims 15 or 16, wherein the step of thermoforming the formable material comprises the step of vacuum forming the formable material.

18. A thermoformed masking strip for masking a gap between a first substrate and a second substrate positioned adjacent the first, the masking strip comprising an edge masking strip having a first face adapted to attach to a mounting surface, and a second face, opposite the first, said first face comprising a first portion adapted to contact the mounting surface and a second portion adapted to co-operate with the mounting surface to form a space with an open end in line of sight of a paint spray, and a gap filler extending from the second face of the masking strip, integral with the second face of the masking strip.