DESC:FIELD OF INVENTION

The present invention relates to roof ditch in automobiles. In particular, the invention relates to a new generation paintable roof ditch seal for automobiles. More particularly, the present invention relates to an integrated weather strip and reactive adhesive tape for automobile applications. The present invention also relates to a method for making such an integrated roof-ditch.

BACKGROUND OF THE INVENTION

In most of the passenger cars, the roof ditch is formed by joining of the outer side panel of the body, roof panel and the reinforcement panel by welding across its length. This roof ditch area needs to be sealed carefully by using a sealant and flexible rubber weather strips in order to avoid any water stagnation or entry of air and water into the passenger compartment of the automobile. Therefore, the roof ditch is an important component/sub-assembly of an automobile.

This joint is sealed properly with a polymeric sealant composition, which is cross-linked during the sealant baking process. Subsequently, a moderately flexible weather strip is mounted thereon to improve the aesthetics of the automobile and also to prevent water clogging and subsequent corrosion arising out of water entry through this joint.

The flexible weather strip also plays an important function of arresting the air entry into the passenger compartment, which may lead to NVH issues as well as poor HVAC performance, and which may ultimately cause customer discomfort.

DISADVANTAGES WITH THE PRIOR ART

If the sealant and weather strip used do not remain in the designed locations on the roof ditch, this may lead to entry of air and water inside the passenger compartment of the automobile.

This in turn may raise serious corrosion issues, NVH issues, sagging of roof trim over a period of time and bring discomfort to the customer. This may finally lead to poor acceptance of the automobile and cause loss of confidence among the customers and failure of model in today’s quality conscious market.

The best Available solution for the application could be PVC based paintable sealants, but they have numerous disadvantages. These are not user-friendly and can be applied only through Robotic Application for imparting a good visual or aesthetic appeal to it. This requires a substantial capital investment in machinery. The operational cost is also much more than the normal sealant application process.

The presently available product is not also eco-friendly and thus it cannot be recycled and needs to be straight away discarded in the landfill. It also requires a lot of storage space, so the handling and logistics is also not economically viable.

The shelf life of the product is very small and thus, it cannot be stored over a long period of time.

Finally, it is not designer friendly, because of occurrence of its sagging over extended periods of time due to various factors, such as temperature, cracking etc.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to eliminate issues related to quality, cost, aesthetic and durability of the weather strips for roof ditch in an automobile.

Another object of the present invention is to provide a low-cost weather strips for roof ditch in an automobile.

Still another object of the present invention is to provide an aesthetically appealing weather strips for roof ditch in an automobile.

Yet another object of the present invention is to provide a durable integrated weather strips and reactive adhesive tapes for roof ditch in an automobile.

Still further object of the present invention is to provide a sustainable and recyclable weather strips for roof ditch in an automobile.

Yet further object of the present invention is to provide automobile weather strips to reduce water leakage through / corrosion in roof ditch on the side joints of the vehicle body.

These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a new-generation paintable integrated roof-ditch seal for automotive application, the roof-ditch seal comprising:

• a base layer configured as a release liner;

• an intermediate layer to be pasted on the base layer; and

• a top layer to be applied on the intermediate layer.

Typically, the base layer is a silicone-based release liner and is preferably released prior to assembly.

Typically, the intermediate layer is a reactive cross-linkable epoxy or butyl-based adhesive preformed tape pasted on the base layer.

Typically, the intermediate layer is a reactive pressure sensitive cross-linkable hot melt adhesive tape pasted on the base layer.

Typically, the top layer is a polar polyester-based thermoplastic elastomer, which is applied on the intermediate layer to complete the seal on the roof ditch joinery.

Typically, the completed roof-ditch joinery is body-colored in the color of the Body-in-white (BIW).

Typically, the new-generation paintable integrated roof-ditch seal for automotive application comprises:

• a base layer configured as a silicone-based release liner preferably released prior to the roof-ditch assembly;

• an intermediate layer configured as a reactive cross-linkable butyl-based adhesive preformed tape or a hot melt adhesive tape pasted on the base layer; and

• a top layer configured as a polar polyester-based thermoplastic elastomer applied on the intermediate layer to complete the seal on the roof ditch joinery.

Typically, the completed roof-ditch joinery is body-colored in the color of the Body-in-white (BIW).

In accordance with the present invention, there is also provided a method for making a new-generation paintable integrated roof-ditch seal for automotive application, comprising the steps of:

• electrophoretic deposition of the roof ditch in the paint shop followed by baking in an Electrophoretic Deposition (ED) oven;

• pasting a roof-ditch seal and applying a roller thereon;

• transferring the prepared roof ditch to a sealer oven for baking;

• painting the top coat, baking and transferring to the TCF line

wherein Silicone-based release liner is released prior to the roof-ditch assembly, followed by pasting an intermediate layer of reactive cross-linkable epoxy or butyl-based adhesive preformed tape pressure sensitive hot melt adhesive tape on this base layer, and finally applying a top layer of polar polyester-based thermoplastic elastomer to complete the seal on the roof ditch joinery.

Typically, the completed roof-ditch joinery is painted body-colored by using the same paints as applied on the Body-in-white (BIW).

DESCRIPTION OF THE PRESENT INVENTION

The Sealant serves two purposes. First and foremost it seals the joinery to prevent entry of air, dust and water and it also helps to manage the gap and flush, in order to ensure a proper base formation for subsequent weather strip assembly.

The weather strip is assembled to cover the roof ditch by using a pair of plastic or metallic clips to firmly hold it on the body-in-white (BIW) at two locations along the longitudinal axis thereof. Out of these two weather strips, one is present on the LHS and the other on the RHS in the vehicle. In order to ensure a zero gap and to make it aesthetically pleasing, the weather strip is bonded to the BIW across the entire length of the sealant using a polymeric pressure sensitive adhesive tape.

Although, rubber weather strips are predominantly used, which are non-recyclable and have poor aesthetic appeal, there is always a need to maintain a long-term aesthetic appeal, in terms of ozone resistance and weather resistance.

Furthermore, the rubber weather strip needs to be predominantly made of black colour in order to achieve the above objectives.
Therefore, the vehicle designers are not left with many options in terms of the colour thereof.

A subsequent analysis of the customer complaints pointed to a lacuna between the actual conditions of the weather strips in the field vis-à-vis the design objectives and indicated that few cases of poor surface quality of the weather strips also occurred due to environmental degradation thereof.

With passenger cars becoming fashion accessories and status symbol, which are often expressed with wide-ranging buying preferences decided by the aesthetics of the vehicles, the modern customers expect their cars to be capable of delighting them in terms of their superior perceived quality.

With technologies ranging from Body colored bumpers to chrome finished decor, today’s automobile designers are on a constant quest of offering cars, having a thematic design.

Against this backdrop, an idea was conceived to replace the black weather strip with a body colored weather strips and this idea is the main aspect underlying the present invention.

Another idea related concept consists of assembling the weather strips in the paint shop rather than in the trim shop of the automobile manufacturing facility. The advantages of this second concept are obvious in terms of enhanced productivity and mitigation of complex tooling, which in turn leads to improvement in the Turn-Around Time (TAT).

These twin objectives are suitably met by using a pressure sensitive tape, which apart from its primary role of being an adhesive by bonding of the body colored weather strip to the sheet metal, simultaneously also functions as a sealant for sealing the joinery. The weather strip obtains its body colored paint from the paints that are sprayed on the body-in-white.

Therefore, the need for provisioning of separate stations in the trim shop is totally eliminated, which also leads to cost advantages in the roof ditch manufacture in the automobile plants.

The idea underlying the present invention also includes manufacture and application of body colored Roof ditch weather strips, manufactured using the Extrusion process, which are predominantly based on a Thermoplastic elastomer that is completely recyclable, thereby offer increase in the overall R&R score for a given vehicle. Any such sustainable solution also brings about significant cost savings at the automobile manufacturer’s end, since the turn-around-time for making a thermoplastic elastomer weather strip is substantially lesser as compared to the conventional Ethylene Propylene Diene Monomer (EPDM) based rubber weather strip.

Therefore, the best approach for the assembly is to mount the weather strip onto the roof ditch by using preformed tapes of curable epoxy or butyl based adhesive or hot melt pressure sensitive adhesive tapes.

Accordingly, the present invention includes the following components:

(i) Silicone-based Release Liner A used as the base of the roof ditch seal, which can be released before the assembly;

(ii) Reactive epoxy or Butyl-based adhesive preformed tapes or Pressure sensitive Hot-melt adhesive tapes B as the cross-linkable intermediate layer; and

(iii) Polyester-based polar Thermoplastic Elastomer C, which can subsequently be body-colored using the same paints as that was used for painting the body-in-white (BIW),

The technical idea behind this disclosure is also to use a Polar Polyester-based thermoplastic elastomer to make the polyester based weather strip that can subsequently be body-colored using the same paints as normally used for painting the body-in-white (BIW), in contrast to the conventionally used non-polar polymers, such as EPDM.
Another technical idea behind this disclosure is to develop a unique assembly mechanism which is reactive and durable and which also eliminates the need for a separate sealant and which avoids subsequent bonding failures due to non-polar rubber based weather strips.

Polymeric Weather strip: It is a polyester base thermoplastic elastomer, flexible, weather resistant, polar and paintable which is the uniqueness of this material and the innovation. Since it is paintable, it helps to replace the conventional black colour seals which are durable and gives better aesthetic appeal.

Reactive Adhesive tape: It is a Crosslinked Epoxy / Butyl base or hot-melt pressure sensitive adhesive tape, compatible with weather strip and gives greater adhesion between the polar weather strip and the body-in-white parts by controlled expansion during curing. This is specially designed in such a way to expand uniformly to the desirable limit and seal properly.

With this invention, it is proposed to offer enhanced quality levels to the customers, which is perceived as without any compromise with the durability aspects of this product. This in turn eliminates the existing issues on field, which range from color fading, chalking and poor aesthetics to corrosion, reduced HVAC performance and NVH.

Since, this offers a 100% foolproof solution to above issues, the related non-value added activities can be completely eliminated in the Trim, Chassis and Final (TCF) line in the automobile manufacturing plant. This also proves itself as an eco-friendly and sustainable solution, thereby making the vehicles equipped with such products significantly cost-efficient and user-friendly.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, which include:

Figure 1 shows a block diagram for the conventional method for performing roof ditch sealing in the TCF line of an automobile manufacturing plant.

Figure 2 shows a block diagram for the improved method in accordance with the present invention for roof ditch sealing for automobiles.

Figure 3 shows the detailed view of the paintable roof ditch seal configured in accordance with the present invention.

Figure 4 shows schematic side view of a roof ditch sealing in an automobile.

Figure 5 shows a detailed view of the roof ditch assembly of an automobile configured in accordance with the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a block diagram of the conventional method with the steps for carrying out the sealing of roof ditch on TCF line in an automobile manufacturing plant. The electrophoretic deposition on the roof ditch is done in the paint shop and is followed by baking in Electrophoretic Deposition (ED) oven at step 10 and subsequently; a seam sealer is applied at step 12. The treated roof ditch is now sent to a sealer oven at step 14 and then clip is mounted at step 16. The top coat paint is applied and the paint coat is baked and the treated roof ditch is transferred to the TCF line at step 18. In parallel, the solvent cleaning is done at step 20 and subsequently a promoter is applied. The adhesive tape is pasted on the sealed roof ditch joint at step 24. Further, the roller application is done at step 26 and finally, the seal is fitted and roller is applied at step 30 on the TCF line.

Figure 2 shows a block diagram for the improved method in accordance with the present invention for roof ditch sealing for automobiles. In this innovative method also, the electrophoretic deposition of the roof ditch is first done in the paint shop and is followed by baking in Electrophoretic Deposition (ED) oven at step 100, the roof ditch seal is pasted and roller is applied at step 112 and subsequently roof ditch is sent to a sealer oven for baking 114. However, here the conventional method of clip mounting step 16 is not applicable and roof ditch directly proceeds to step 118 for top coat painting, baking and then transferred to the TCF line. Moreover, parallel running steps of the conventional method, i.e. solvent cleaning at step 20, promoter application at step 22, adhesive tape pasting at step 24 and the roller application at step 26 are also not applicable here. Finally, the integrated weather strip and reactive adhesive tape fitted on the roof ditch is ready for TCF stage. The roof-ditch so obtained can be readily body-colored using the same paints as applied on the Body-in-white (BIW).

Therefore, the innovative method includes only the 3 following steps:

a) Applying an extruded profile of polyester-based thermoplastic elastomer to on the roof ditch;

b) Pasting on this base layer, another layer of cross-linkable epoxy or butyl based adhesive preformed tapes or pressure sensitive hot melt adhesive tape; and

c) Releasing Silicone-based release liner prior to assembly.

The configuration of the final product obtained after conclusion of the above 3 steps is schematically shown in Figure 3.

Figure 3 shows the detailed view of the paintable roof ditch seal configured in accordance with the present invention. It consists of a first silicone based release liner - which can be released prior to assembly. Subsequently another layer of epoxy or butyl based adhesive preformed tapes or pressure sensitive hot melt adhesive tape B - which can be cross-linked - is pasted on this base layer A. Finally a top layer C of a polyester based thermoplastic elastomer is applied to complete the seal on the roof ditch joinery.

Figure 4 shows a typical schematic side view of a roof ditch seal in an automobile. It shows the front and rear ends 150 and 160 respectively of the roof ditch and the middle area of the seal and ditch has a length L 1.4 meter in the embodiment shown in the example.

Figure 5 shows a detailed cross-sectional view of the roof ditch assembly of an automobile configured in accordance with the present invention. Basically, it consists of a roof panel 142, a roof ditch seal 144, polymeric sealant 146 and a side panel 148 of the body-in-white. The roof ditch seal has a cavity 152 and a metal strip 154 embedded thereunder.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The main advantages of the new-generation paintable roof-ditch seal for automotive application configured according to the present invention are as under:
• Body Colored Roof Ditch Seals offer improved aesthetics without additional paint consumption.

• Improved Weathering Performance.

• Reduction in work content and Turn Around Time in TCF line.

• Sustainable and Recyclable product.

• Reduction in water leakage chances and -corrosion of roof to Body side joints.

• Oven cured permanent and stronger bonding

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps. In the claims and the description, the terms “containing” and “having” are used as linguistically neutral terminologies for the corresponding terms “comprising”.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention. Furthermore, the use of the term “one” shall not exclude the plurality of such features and components described.

The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.

In the previously detailed description, different features have been summarized for improving the conclusiveness of the representation in one or more examples. However, it should be understood that the above description is merely illustrative, but not limiting under any circumstances. It helps in covering all alternatives, modifications and equivalents of the different features and exemplary embodiments.

Many other examples are directly and immediately clear to the skilled person because of his/her professional knowledge in view of the above description.

Therefore, innumerable changes, variations, modifications, alterations may be made and/or integrations in terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention.

These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

The exemplary embodiments were selected and described in order to be able to best represent the principles and their possible practical application underlying the invention. Thereby, the skilled persons can optimally modify and use the invention and its different exemplary embodiments with reference to the intended use. ,CLAIMS:We claim:

1. A new-generation paintable integrated roof-ditch seal for automotive application, the roof-ditch seal comprises:

• base layer configured as a release liner;

• intermediate layer to be pasted on the base layer; and

• top layer to be applied on the intermediate layer.

2. The roof-ditch seal as claimed in claim 1, wherein the base layer is a silicone-based release liner and is preferably released prior to assembly.

3. The roof-ditch seal as claimed in claim 1, wherein the intermediate layer is a reactive cross-linkable epoxy or butyl-based adhesive preformed tape pasted on the base layer.

4. The roof-ditch seal as claimed in claim 1, wherein the intermediate layer is a reactive pressure sensitive cross-linkable hot melt adhesive tape pasted on the base layer.

5. The roof-ditch seal as claimed in claim 1, wherein the top layer is a polar polyester-based thermoplastic elastomer, which is applied on the intermediate layer to complete the seal on the roof ditch joinery.

6. The roof-ditch seal as claimed in claim 5, wherein the completed roof-ditch joinery is body-colored in the color of the Body-in-white (BIW).

7. A new-generation paintable integrated roof-ditch seal for automotive application, the roof-ditch seal comprising:

• a base layer configured as a silicone-based release liner preferably released prior to the roof-ditch assembly;

• an intermediate layer configured as a reactive cross-linkable butyl-based adhesive preformed tape or a hot melt adhesive tape pasted on the base layer; and

• a top layer configured as a polar polyester-based thermoplastic elastomer applied on the intermediate layer to complete the seal on the roof ditch joinery.

8. Roof-ditch seal as claimed in claim 5, wherein the completed roof-ditch joinery is body-colored in the color of the Body-in-white (BIW).

9. A method for making a new-generation paintable integrated roof-ditch seal for automotive application as claimed in claims 1 to 6, wherein the method comprises the steps of:

• electrophoretic deposition of the roof ditch in the paint shop followed by baking in an Electrophoretic Deposition (ED) oven;

• pasting a roof-ditch seal and applying a roller thereon;

• transferring prepared roof ditch to a sealer oven for baking;

• painting the top coat, baking and transferring to the TCF line

wherein Silicone-based release liner is released prior to the roof-ditch assembly, followed by pasting an intermediate layer of reactive cross-linkable epoxy or butyl-based adhesive preformed tape pressure sensitive hot melt adhesive tape on this base layer and finally applying a top layer of polar polyester-based thermoplastic elastomer to complete the seal on the roof ditch joinery.

10. Method as claimed in claim 9, wherein the completed roof-ditch joinery is painted body-colored by using the same paints as applied on the Body-in-white (BIW).

Dated: this day of 28th September,2015. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT