WO2000005058A1

WO2000005058A1 - Weatherseal having an electrically deformed polymer surface and method of manufacture

Info

Publication number: WO2000005058A1
Application number: PCT/US1999/014687
Authority: WO
Inventors: David Harold Berry; Matthew John Leatherman; David T. Zwolinski
Original assignee: Schlegel Corporation
Priority date: 1998-07-20
Filing date: 1999-06-28
Publication date: 2000-02-03
Also published as: WO2000005058A8; WO2000005058A9

Abstract

A weatherseal is disclosed including a thermoplastic contact layer having a surface texture in a molten phase to an electric field. The surface texture is a choppy, chaotic texture of peaks or ridges and troughs. The contact layer may be located on any of a variety of substrates including thermoplastic or thermoset, which in turn may be reinforced or unreinforced.

Description

WEATHERSEAL HAVING AN ELECTRICALLY DEFORMED

POLYMER SURFACE AND METHOD OF MANUFACTURE

Field of the Invention

The present invention relates to a seal for releasably contacting a panel, and particularly, to a weatherseal for releasably contacting a glass panel in an automobile, wherein the weatherseal includes a contact surface with a reduced coefficient of friction for allowing the glass panel to be moved smoothly into and out of contact with the weatherseal, while reducing passage of water or air between a seated glass panel and the weatherseal. The present invention further relates to sealing surfaces, and more particularly, to a weatherseal having a textured polymer contact surface formed by exposure of the polymer to an electric field.

Background of the Invention

Many vehicles employ windows formed of glass panels, wherein the window is moveable relative to a portion of the vehicle. A common construction includes the use of a glass panel in a door, wherein the door and the glass panel move relative to the remainder of the vehicle, and the glass panel moves relative to the door and hence seal. In this construction, the glass panel is frequently moved between an open position and closed position with respect to the door and/or a portion of the vehicle frame. Increased business transactions such as restaurant, banking and pharmacy services are now regularly offered in a drive-through format. These transactions require the repeated release and engagement of the glass panel and vehicle. The repeated opening and closing of the glass panel places significant stress on the seal between the glass panel and the vehicle.

Traditionally, a weather strip is employed at the interface between the glass panel and the vehicle door and/or the vehicle. The interface between the weather strip and the glass panel must be sufficient to substantially preclude the penetration of water and air along the periphery of the glass panel, while still permitting ready engagement and disengagement of the glass panel without requiring significant force.

Conventional sealing structures include a soft synthetic resin or synthetic rubber. However, such weather strips do not provide for the ready opening and closing of the glass panel relative to the seal. Often, a large force is loaded on the glass panel which resists opening or closing of the glass panel.

Prior weather strips often employed a fiber flocking on the area in which the weather strip contacts the glass panel. However, the flocking process is relatively complicated. The complex manufacturing process adds to the cost of the weather strip. Further, the flocking is relatively easily removed or worn away. As the flocking is worn from the weather strip, the loading force substantially increases.

Therefore, the need exists for a weatherseal that has reduced force requirements for moving a panel into and out of engagement with the weatherseal. The need also exists for a weatherseal having enhanced wear capabilities. A need also exists for a method of forming a low friction weatherseal. Summary of the Invention

The present invention encompasses a weatherseal having a textured contact surface for reducing friction with a panel. The weatherseal includes a substrate which provides a base upon which a contact layer is disposed. The substrate may be any of a variety of profiles or configurations, including reinforced and unreinforced, as well as single or multiple component to provide desired rigidities. The contact layer is a thermoplastic material that has been electrically deformed to create a textured surface.

In one configuration, the substrate is one of a thermoplastic or a thermoset material, that may have a reinforcing member. The contact layer is located on, at least, a portion of the weatherseal that contacts a panel. The contact layer is a thermoplastic such as polyethylene or polypropylene that has been exposed to a sufficient electric field, such as an electrostatic field, when at a sufficient temperature, to form a surface texture having a reduced contact area. The electrically deformed thermoplastic of the contact layer is then cooled at a sufficient rate to retain at least a portion of the surface texture. Brief Description of the Drawings

Figure 1 is a perspective view of an unreinforced seal incorporating the present invention.

Figure 2 is a perspective view of a reinforced seal incorporating the present invention. Figure 3 is a perspective view of an upper auxiliary seal incorporating the present invention.

Figure 4 is a top view of a contact layer of the present weatherseal.

Figure 5 is an enlarged top view of a contact layer that has not been processed by the present invention.

Figure 6 is a cross-sectional view of a portion of the seal of Figure 5.

Figure 7 is an enlarged top view of a contact layer of the present invention.

Figure 8 is a partial cross-sectional view of the seal of Figure 7.

Figure 9 is an enlarged top view of an alternative contact layer of the present invention.

Figure 10 is a partial cross-sectional view of the seal of Figure 9.

Figure 11 is a graph of the relationship between static coefficient of friction (C.O.F.) of the contact layer and a deforming electrical charge.

Figure 12 is a graph of the relationship between dynamic coefficient of friction (C.O.F.) of the contact layer and a deforming electrical charge.

Figure 13 is a schematic view of a processing line for forming the present seal.

Detailed Description of the Preferred Embodiment

The present invention encompasses a weatherseal 10 for releaseably and repeatedly engaging a panel. The weatherseal 10 of the present invention includes a substrate 40 and a contact layer 60, wherein the contact layer defines an area of contact between the weatherseal and the panel. The panel may be any of a variety of materials and does not limit the present invention. For example, the panel may be glass, metal or a composite, which is painted, surface treated or bare. In the operating environment, the panel is brought repeatedly into and out of engagement with the weatherseal 10. The engagement of the panel and the weatherseal 10 may result from motion of the panel, relative to the weatherseal.

The substrate 40 forms a base upon which the contact layer 60 is disposed and may be formed of a variety of materials including thermoplastic or thermosetting materials, such as TPE or EPDM or any combination thereof. Thus, the substrate 40 may have a relatively rigid portion and a relative soft portion. The substrate 40 may include a reinforcing member 42 such as a wire or metal carrier. It is contemplated, the substrate 40 may include a thermoplastic portion and a thermoset portion each having a unique rigidity. In addition, the substrate 40 may be formed of differing thickness to provide differing amounts of rigidity.

The contact layer 60 is located on the areas of the substrate 40 that contact the panel. The contact layer 60 is sufficiently connected to the substrate 40 to preclude unintended separation during operation. The contact layer 60 may be connected to the substrate 40 by mechanical or chemical bonding, such as heat bonding or adhesives. While the contact layer 60 may have a variety of thickness, at least partially dictated by the operating parameters of the weatherseal 10 and substrate 40, typical thickness of the contact layer are approximately 10 microns to approximately 1000 microns. The contact layer 60 generally has a thickness between approximately 40 microns to approximately 600 microns.

The contact layer 60 is a thermoplastic material, and preferably, an olefinic material with a high melt flow index. It is understood the contact layer 60 may include various fillers or additives and retain its thermoplastic nature. Preferably, the thermoplastic of the contact layer 60 has a melting temperature which is less than the melting temperature or degradation temperature of the substrate 40. The contact layer 60 has a surface 62 that is textured or convoluted. The texture of the contact layer surface 62 is selected to provide a multitude of raised portions 66 and recessed portions 68. wherein the raised portions define the area of contact between the weatherseal and the panel. The raised portions 66 or projections have a sufficient strength to substantially preclude deformation, fracture or failure upon engagement with the panel. The surface texture of the contact layer 60 is shown in Figures 4 and 7-10. The surface texture is a roughened texture or choppy having relatively abrupt transitions among a plurality of raised 66 and recessed 68 portions. These raised 66 portions and recessed 68 portions may appear as waves or undulations, generally having peaks and troughs. Unlike embossed surfaces, pressed surfaces or calandered surfaces, the surface texture 62 is non-repeating. That is, the contours are random. Thus, the surface texture 62 does not have a fixed frequency. The surface texture 62 is chaotic having raised 66 and recessed 68 areas within a general size range, but the particular size and location of a particular raised or recessed area are not predictable. As the contact layer 60 includes raised portions 66, upon engagement with the panel, the raised portions provide a reduced surface area for engagement with the panel.

As discussed in the method of manufacture, the contact layer 60 may be formed with a variety of texture configurations. The undulations may range from relatively high frequency, relatively peaked ripples, to generally rounded relatively low height rolling projections. Alternatively, the contact layer 60 may have a relatively creased or wrinkled surface 62 in a chaotic pattern. Method of Manufacture

Generally as shown in Figure 13, the present weatherseal 10 is formed by exposing a molten portion of the contact layer 60 to an electric field and particularly an electrostatic field. In Figure 13, the process path for the extrudate extends from the upper left to the lower right. Initially, the contact layer 60 is in a molten phase MP. The thermoplastic material of the contact layer 60 may be extruded or coextruded onto the substrate 40. Such extruded thermoplastic will have a molten surface downstream of the die. The electrostatic charge may be applied at a location in the processing line where the contact layer 60 has a molten surface. As the contact layer is thermoplastic, a portion of the layer is rendered by heating. The heating may be accomplished by a variety of ways such as heated air, radiation (infra red) or microwave. That is, at least, the surface of the contact layer 60 is heated above its melting point to form a molten or fluid portion.

The molten portion of the contact layer 60 is then exposed to an electric field such as an electrostatic field. An electrostatic field is generated from an electrode 70 proximal to the molten contact layer 60. The electrode 70 may be in the form of a grid. The voltage applied is at least partially determined by the particular material of the contact layer 60, the temperature of molten material, the proximity of the electrode 70 to the molten material and the desired surface texture. Thus, the contact layer 60 travels through a deformation area DA.

For electrodes within approximately 1/2^*' of the molten polypropylene contact layer 60, voltages of between approximately 45 kv to 65 kv have produced significantly reduced static and dynamic coefficients of friction, as shown in Figures 11 and 12. As shown in Figures 5 and 6, a contact layer is formed without any exposure to an electric field and has no relevant surface texture. Referring to Figures 7 and 8, a surface 62 is formed from exposing a 50kv charge to molten polypropylene at a distance of approximately 1/2 inch. As shown in Figures 9 and 10, a surface 62 is formed from exposure to a 65kv charge. However, the charge range may be between 5kv to approximately 100 kv. The resulting disturbance in the molten portion of the contact layer produces a surface texture in the molten material as shown in Figure 4.

It is believed that the amount of voltage within the electric field such as the electrostatic field in combination the proximity of the electrode to the molten layer, is an important parameter is determining the characteristics of the surface texture. Generally, as the strength of the electrostatic field increases, the slope of the surfaces and height of the peaks increases within the molten surface layer and hence the roughness of the contact layer increases.

Further, the viscosity of the molten portion of the contact layer affects the resulting surface texture. Generally, the more fluid the molten portion, the sharper the peaks. Conversely, the more viscous the molten material, the rounder the peaks.

In contrast, when an increased viscosity of the material is employed, the surface may exhibit relatively small irregularities and resemble a leather grained appearance.

It is contemplated the contact layer 60 may be disposed on the substrate 40 and allowed to completely cool. At a later time, the contact layer 60 is heated to above its melting point.

Conversely, the contact layer 60 may be in the form of a tape that is processed to form the surface texture 62, wherein the tape is subsequently disposed on the substrate 40.

The temperature of the molten material and the strength of the electric charge such as electrostatic charges are controlled in connection with a cooling of the thermoplastic material to retain the contoured, or textured surface of the contact layer.

The weatherseal 10 is then passed to the cooling station where the thermoplastic of the contact layer is sufficiently cooled with a sufficient temperature gradient to retain a desired amount of surface texture.

The cooling of the molten contact layer is preferably accomplished as quickly as possible. It has been found that impacting a cooling stream CS against the molten portion of the contact layer provides sufficient cooling. The cooling stream CS may include air, cooled air. water, cooled water or any other liquid or gas that is inert with respect to the material of the contact layer 60. Preferably, impacting the cooling stream CS does not substantially alter the induced surface texture. The temperature differential between the cooling stream CS and the molten contact layer 60 is also a parameter in determining the surface texture. Alternatively, the molten contact layer 60 may be cooled by immersing or partially immersing the contact layer in a cooling bath.

It is believed a weatherseal 10 having a contact surface 62 textured by an electric field, decreases the coefficient of friction for the thermoplastic material. As shown in Figures 1 1 and 12. has been found that forming a surface texture 62 on the contact layer 60 from exposure to the electric field reduces both the static and the dynamic coefficient of friction of the weatherseal, while the contact layer still provides the sealing function. The present invention obviates the need for a an embossing procedure such as a contacting roller. Further, by allowing the single material of the contact layer to form a relatively low friction surface, additional materials are not necessary and hence the cost of the weatherseal is reduced.

Prior weatherseals often generate noise upon movement between the weatherseal and the panel. The noise producing movement includes the motion associated with engaging and disengaging the panel, as well as the slight movement that often occurs when the panel is in the engaged position. That is. although the panel remains engaged with the weatherseal, stress on the vehicle often causes the panel to move slightly with respect to weatherseal. This movement generates noise, often characterized as chirp, chatter, squeak and itch.

It has been found that a weatherseal having the present contact layer reduces the noise generated upon motion of the panel relative to the weatherseal under both wet and dry conditions.

While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt the invention to a particular situation without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims.

Claims

In the Claims

1. A method of forming a surface texture in a thermoplastic contact layer of a weatherseal, comprising:

(a) disposing a thermoplastic contact layer on a portion of a substrate;

(b) rendering a portion of the thermoplastic contact layer in a molten phase;

(c) exposing the molten phase to an electric field to form a surface texture; and

(d) transforming the molten phase to a solid phase to substantially retain the surface profile.

2. The method of Claim 1, further comprising forming the surface texture to include a multitude of wave forms.

3. The method of Claim 1, further comprising employing an electrostatic field.

4. A method of forming a surface texture in a thermoplastic contact layer of a weatherseal, comprising:

(a) deforming the thermoplastic contact layer in a fluid phase with an electric field to induce a surface texture; and

(b) converting the deformed fluid phase thermoplastic contact layer to a solid phase to retain the surface texture.

5. The method of Claim 4, wherein deforming the thermoplastic contact layer includes raising a temperature of the thermoplastic above a melting temperature of the thermoplastic.

6. The method of Claim 4, wherein converting the deformed thermoplastic contact layer to a solid phase includes impinging a cooling stream on the contact layer.

7. The method of Claim 4, further comprising employing an electrostatic field as the electric field.

8. A method of forming a surface texture in a thermoplastic contact layer of a weatherseal, comprising:

(a) converting at least a portion the thermoplastic contact layer to a molten phase; (b) exposing the molten phase to an electric field to create the surface texture; and

(b) transforming the exposed molten phase to a substantially solid phase.

9. The method of Claim 8, further comprising employing an electrostatic field as the electric field.

10. A method of forming a surface texture in a thermoplastic contact layer of a weatherseal, comprising:

(a) exposing at least a portion of a molten thermoplastic contact layer to an electric field to form a surface texture; and

(b) cooling the molten thermoplastic contact layer to retain at least a portion of the surface texture.

11. A method of forming a surface texture in a thermoplastic contact layer of a weatherseal, comprising:

(a) subjecting the thermoplastic contact layer in a first state to an electric field to form a surface texture, and

(b) converting the thermoplastic contact layer to a second state to substantially retain the surface texture.

12. A thermoplastic contact layer of a weatherseal, comprising:

(a) a surface texture on the thermoplastic contact layer formed by exposure of a molten phase of the contact layer to an electric field.

13. A weatherseal having a thermoplastic contact layer for releasably contacting a panel, comprising:

(a) a resilient substrate; and

(b) a thermoplastic contact layer on at least a portion of the substrate, the contact layer having a multitude of non repeating projections, the projections being an integral and unitary portion of the contact layer, and having a reduced contact area to reduce friction with the panel.

14. A weatherseal having a thermoplastic contact layer for releasably contacting a panel, comprising: (a) a resilient substrate; and

(b) a thermoplastic contact layer on a portion of the substrate, the contact layer having a multitude of non repeating projections, the projections being an integral and unitary portion of the contact layer having the same composition as the remaining contact layer, and having a reduced contact area to reduce noise generated by contact between the weatherseal and the panel.