Abstract:
A method of sealing an interface, the method comprising: providing a sealant material, locating the sealant material adjacent to the interface, exposing the sealant material to an elevated temperature such that the sealant material flows adjacent the interface, and curing the sealant material to seal the interface.

Description:
CLAIM OF PRIORITY 
     To the extent applicable, the present invention claims the benefit of the priority of U.S. Provisional Application Ser. No. 60/589,701, filed Jul. 21, 2004, the contents of which are incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a sealant material for sealing a component of an article of manufacture such as an automotive vehicle. 
     BACKGROUND OF THE INVENTION 
     Sealant materials are often applied to a surface for sealing or for otherwise covering the surface, including any joints associated therewith. There presently exist a vast number of sealant materials that serve these purposes for different articles of manufacture. However, in certain circumstances, it may be desirable for sealant materials to serve other additional purposes depending on the components or articles of manufacture to which the sealant materials are applied. 
     For example, in some industries, such as the furniture, appliance or automotive industries, joints are often part of a show surface, and are thus visible to a user or consumer. Accordingly, one desirable characteristic for a sealant material covering a joint is to provide a generally smooth or continuously or controlled patterned surface that is cosmetically pleasing. If colorant is not already included in the sealant, but a color is desirable, preferably the sealant material is paintable or otherwise coatable. 
     As another example, it may be desirable for a sealant material to be compatible with other components of an article of manufacture. For instance, it may be desirable for a sealant material to provide a relatively smooth and consistent surface such that a component of an article of manufacture may be contacted with that sealant material without surface inconsistencies of the sealant material showing or reading through the component. 
     Certain assembly operations in the aforenoted industries and others, require that a sealant material be heated along with the article to which it is applied. For instance, some priming or painting operations are conducted at elevated temperatures. Thus, another desirable trait for certain sealants is that they exhibit attractive temperature response characteristics for a desired application (e.g., a sealant material preferably does not exhibit random oozing, bubbling, rippling, or the like). 
     SUMMARY OF THE INVENTION 
     A sealant material and method of using the sealant material are disclosed. The sealant material is typically activatable to flow, cure, expand or a combination thereof upon exposure to a condition such as heat. Preferably, the sealant material includes an ingredient, shape, configuration or otherwise for inhibiting the flow of bubbles through the sealant material during activation thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description: 
         FIG. 1A  illustrates a perspective view of an exemplary sealant material formed according to the present invention and disposed upon an exemplary substrate; 
         FIG. 1B  illustrates a sectional view of the exemplary sealant material and substrate of  FIG. 1A  after activation of the sealant material; 
         FIG. 2  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 3  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 4  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 5  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 6  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 7  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 8  is a graph of an exemplary response to heat exhibited by an exemplary sealant material; 
         FIG. 9  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 10  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 11  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 12  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 13  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 14  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 15  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIG. 16  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention; 
         FIGS. 16A-16C  illustrates a variety of exemplary sealant materials according to the present invention; and 
         FIG. 17  illustrates a sectional view of another exemplary sealant material disposed upon an exemplary substrate in accordance with an aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is predicated upon the provision of an improved sealant material and articles incorporating the same. The sealant material may include any combination of formulation improvements or design improvements disclosed herein. For example, and without limitation, the sealant material may include: a hardened surface; a tailored surface energy; a layer of blocking material; two or more portions of different material; one or more waxes; a tailored curing rate; particular positioning of the sealant material; masses for blocking bubbles; a coating, combinations thereof, the like or others. As another example, the sealant material may be part of an assembly that is to be assembled to an article of manufacture. 
     Examples of other sealant materials including physical designs of sealant materials and formulations of sealant materials, both of which may be used in conjunction with or as part of the sealant material of the present invention, are disclosed in the following references: U.S. Pat. Nos. 6,350,791; 6,489,023; 6,720,387; 6,742,258; 6,747,074; 2004/0033324; 2004/0016564; WO 02/086003; WO 03/103921; WO 03/072677; WO 03/011954; WO 2004/037509; EP 0 742 814 B1; EP 1 240 266 B1; copending U.S. Provisional Application Ser. No. 60/558,594, filed Apr. 1, 2004, titled “Sealant Material” and copending U.S. Provisional Application Ser. No. 60/577,027, filed Jun. 4, 2004, titled “Sealant Material”, all of which are incorporated herein by reference for all purposes. 
     Referring to  FIG. 1 , there is illustrated one exemplary basic design of a sealant material  10  that may have an improved formulation according to the present invention. Of course, it should be understood that the formulations disclosed herein may be used in any of the physical designs of any sealant material disclosed herein or any other sealant material. 
     It is generally contemplated that, the sealant material may be formed in a variety of shapes or configurations. In the embodiment illustrated in  FIG. 1 , the sealant material  10  is an elongated strip that extends along a length (L) and has a rectangular cross-section perpendicular to that length (L). 
     The sealant material may be used to cover, seal, reinforce, provide acoustic damping or the like to a variety of members or components of a variety of articles of manufacture. In the embodiment illustrated in  FIG. 1 , the sealant material  10  is placed within an opening  30  (e.g., a cavity, ditch or recess) that is formed by panels  14 ,  16 . In the particular embodiment illustrated, the opening  30  is a roof ditch of an automotive vehicle that is typically formed from body panels of the vehicle. As shown, the overlapping ends  24  of the panels  14 ,  16  at least partially define the opening  30  and the overlapping ends  24  form an interface  34  between the two panels  14 ,  16 . Typically, the interface  34  will define one or more gaps  36  between the overlapping ends  24  of the panels  14 ,  16 , even though effort is typically expended to minimize such gaps  36  for articles of manufacture such as automotive vehicles. In the embodiment shown, the sealant material  10  overlays the interface  34 . 
     The expandable material is typically configured to activate upon exposure to a stimulus such as heat or others as discussed below. Upon activation, the sealant material typically softens, melts, cures, possibly expands, a combination thereof or the like. In  FIG. 1B , the expandable material  10  has been activated to soften and/or melt such that it flows and whets the substrate or the panels  14 ,  16  about the interface  34  thereby sealing the interface  34 , the gap  36  or both formed by the panels  14 ,  16 . 
     Generally, it is contemplated that a variety of materials can be employed in the sealant material. Thus, the preferred materials discussed herein should not be considered limiting unless otherwise stated. 
     Epoxy Materials 
     Epoxy materials can be particularly suitable for the sealant material of the present invention. Epoxy resin is used herein to mean any of the conventional dimeric, oligomeric or polymeric epoxy materials containing at least one epoxy functional group. The polymer based materials may be epoxy containing materials having one or more oxirane rings polymerizable by a ring opening reaction. In preferred embodiments, the sealant material includes up to about 80% of an epoxy resin. More preferably, the sealant includes between about 10% and 50% by weight of epoxy containing materials. 
     The epoxy containing materials may be aliphatic, cycloaliphatic, aromatic or the like. The epoxy may be supplied as a solid (e.g., as pellets, chunks, pieces or the like) or a liquid (e.g., an epoxy resin) or both. The epoxy may be blended with one or more ethylene copolymers or terpolymers that may possess an alpha-olefin. As a copolymer or terpolymer, the polymer is composed of two or more different monomers, i.e., small chemically reactive molecules that are capable of linking up with each other or similar molecules. Preferably, an epoxy resin is added to the sealant material to increase the flow properties of the material. One exemplary epoxy resin may be a phenolic resin, which may be a novalac type or other type resin. Other preferred epoxy containing materials may include a bisphenol-A epichlorohydrin ether polymer, or a bisphenol-A epoxy resin which may be modified with butadiene or another polymeric additive. 
     Epoxy/Elastomer 
     One or more of the epoxy containing materials may be provided to the sealant material as an epoxy/elastomer hybrid, e.g., a blend, copolymer or adduct that has been previously fabricated. The epoxy/elastomer hybrid, if included, may be included in an amount of up to about 90% by weight of the sealant material. Typically, the epoxy/elastomer hybrid is approximately 1 to 50% and more typically is approximately 5 to 20% by weight of the sealant material. 
     In turn, the hybrid itself generally includes about 1:5 to 5:1 parts of epoxy to elastomer, and more preferably about 1:3 to 3:1 parts or epoxy to elastomer. In one preferred embodiment, the epoxy/elastomer hybrid preferably includes approximately 40 to 80% of an epoxy resin (such as disclosed in the above), and about 20 to 60% of an elastomer compound. The elastomer compound may be any suitable art disclosed thermoplastic elastomer, thermosetting elastomer or a mixture thereof. Exemplary elastomers include, without limitation natural rubber, styrenebutadiene rubber, polyisoprene, polyisobutylene, polybutadiene, isoprene-butadiene copolymer, neoprene, nitrile rubber, butyl rubber, polysulfide elastomer, acrylic elastomer, acrylonitrile elastomers, silicone rubber, polysiloxanes, polyester rubber, diisocyanate-linked condensation elastomer, EPDM (ethylene propylene diene rubbers), chlorosulphonated polyethylene, fluorinated hydrocarbons and the like. In one embodiment, recycled tire rubber is employed. 
     The epoxy/elastomer hybrid, when added to the sealant material, preferably is added to modify structural properties of the sealant material such as strength, toughness, stiffness, flexural modulus, or the like. Additionally, the epoxy/elastomer hybrid may be selected to render the sealant material more compatible with coatings such as water-borne paint or primer system or other conventional coatings. 
     Rheology Modifier 
     The sealant material can also include one or more materials for controlling the rheological characteristics of the sealant material over a range of temperatures (e.g., up to about 250° C. or greater). 
     In one embodiment, any suitable art-disclosed rheology modifier may be used, and thus the rheology modifier may be organic or inorganic, liquid or solid, or otherwise. In one preferred embodiment, the rheology modifier is a polymer, and more preferably one based upon an olefinic (e.g., an ethylene, a butylenes, a propylene or the like), a styrenic (e.g., a styrene-butadiene-containing rubber), an acrylic or an unsaturated carboxylic acid or its ester (such as acrylates, methacrylates or mixtures thereof; e.g., ethylene methyl acrylate (EMA) polymer) or acetates (e.g., EVA). The rheology modifier may be provided in a generally homogeneous state or suitable compounded with other ingredients. It is also contemplated that the various clays, minerals or other materials discussed in relation to fillers below can be employed to modify rheology of the sealant material. 
     Blowing Agent 
     Optionally, one or more blowing agents may be added to the sealant material, although for some applications the sealant material will be substantially or entirely devoid of blowing agent or blowing agent accelerator. When used, the blowing agent typically produces inert gasses that form as desired an open and/or closed cellular structure within the sealant material. In this manner, it may be possible to lower the density of articles fabricated from the material. In addition, the material expansion can help to improve sealing or wetting capability. 
     The blowing agent may include one or more nitrogen containing groups such as amides, amines and the like. Examples of suitable blowing agents include azodicarbonamide, dinitrosopentamethylenetetramine, azodicarbonamide, dinitrosopentamethylenetetramine, 4,4 i oxy-bis-(benzenesulphonylhydrazide), trihydrazinotriazine and N, N i -dimethyl-N,N i  dinitrosoterephthalamide. In a one embodiment, modified and unmodified azocarbonamides may be supplied to the material  10  in particle form having particles sizes of, for example, 120 and 180 microns. Advantageously, the azocarbonamides can assist the sealant material in leveling itself (i.e., forming a surface of maintaining the surface  24  in a substantially flat condition). 
     An accelerator for the blowing agents may also be provided in the sealant material. Various accelerators may be used to increase the rate at which the blowing agents form inert gasses. One preferred blowing agent accelerator is a metal salt, or is an oxide, e.g. a metal oxide, such as zinc oxide. 
     Amounts of blowing agents and blowing agent accelerators can vary widely within the sealant material depending upon the type of cellular structure desired, the desired amount of expansion of the sealant material, the desired rate of expansion and the like. Exemplary ranges for the amounts of blowing agents and blowing agent accelerators in the sealant material range from about 0% by weight to about 5% by weight and are preferably in the sealant material in fractions of weight percentages. 
     Curing Agent 
     One or more curing agents and/or curing agent accelerators may be added to the sealant material. Amounts of curing agents and curing agent accelerators can, like the blowing agents, vary widely within the sealant material depending upon the type of cellular structure desired, the desired amount of expansion of the sealant material, the desired rate of expansion, the desired structural properties of the sealant material and the like. Exemplary ranges for the curing agents, curing agent accelerators or both present in the sealant material range from about 0% by weight to about 7% by weight. 
     Preferably, the curing agents assist the sealant material in curing by crosslinking of the polymers, epoxy resins or both. It is also preferable for the curing agents to assist in thermosetting the sealant material. Useful classes of curing agents are materials selected from aliphatic or aromatic amines or their respective adducts, amidoamines, polyamides, cycloaliphatic amines (e.g., anhydrides, polycarboxylic polyesters, isocyanates, phenol-based resins (such as phenol or cresol novolak resins, copolymers such as those of phenol terpene, polyvinyl phenol, or bisphenol-A formaldehyde copolymers, bishydroxyphenyl alkanes or the like), or mixtures thereof. Particular preferred curing agents include modified and unmodified polyamines such as triethylenetetramine, diethylenetriamine tetraethylenepentamine, cyanoguanidine and the like. An accelerator for the curing agents (e.g., methylene diphenyl bis urea) may also be provided for preparing the sealant material. 
     Filler 
     The sealant material may also include one or more fillers, including but not limited to particulated materials (e.g., powder), beads, microspheres, or the like. Preferably the filled includes a relatively low-density material that is generally non-reactive with the other components present in the sealant material. 
     Examples of fillers include silica, diatomaceous earth, glass, clay, talc, pigments, colorants, glass beads or bubbles, glass, carbon ceramic fibers, antioxidants, and the like. Such fillers, particularly clays, can assist the sealant material in leveling itself during flow of the material. The clays that may be used as fillers may include clays from the kaolinite, illite, chloritem, smecitite or sepiolite groups. Examples of suitable fillers include, without limitation, talc, vermiculite, pyrophyllite, sauconite, saponite, nontronite, montmorillonite or mixtures thereof. The clays may also include minor amounts of other ingredients such as carbonates, feldspars, micas and quartz. The fillers may also include ammonium chlorides such as dimethyl ammonium chloride and dimethyl benzyl ammonium chloride. Titanium dioxide might also be employed. 
     In one preferred embodiment, one or more mineral or stone type fillers such as calcium carbonate, sodium carbonate or the like may be used as fillers. In another preferred embodiment, silicate minerals such as mica may be used as fillers. It has been found that, in addition to performing the normal functions of a filler, silicate minerals and mica in particular can assist in leveling the sealant material. 
     When employed, the fillers in the sealant material can range from 10% to 90% by weight of the sealant material. According to some embodiments, the sealant material may include from about 0% to about 3% by weight, and more preferably slightly less that 1% by weight clays or similar fillers. Powdered (e.g. about 0.01 to about 50, and more preferably about 1 to 25 micron mean particle diameter) mineral type filler can comprise between about 5% and 70% by weight, more preferably about 40% to about 60%, and still more preferably approximately 55% by weight of the sealant material. In one highly preferred embodiment the sealant material may contain approximately 7% by weight mica. 
     Other Additives 
     Other additives, agents or performance modifiers may also be included in the sealant material as desired, including but not limited to a UV resistant agent, a flame retardant, an impact modifier, a heat stabilizer, a colorant, a processing aid, a lubricant, a reinforcement (e.g., chopped or continuous glass, ceramic, aramid, or carbon fiber or the like). 
     Other polymers may also be incorporated into the sealant material, e.g., by copolymerization, by blending, or otherwise. For example, without limitation, other polymers that might be appropriately incorporated into the sealant material include halogenated polymers, polycarbonates, polyketones, urethanes, polyesters, silanes, sulfones, allyls, olefins, styrenes, acetates, ethyelene vinyl acetates, acrylates, methacrylates, epoxies, silicones, phenolics, rubbers, polyphenylene oxides, terphthalates, or mixtures thereof. Other potential polymeric materials may be or may include, without limitation, polyethylene, polypropylene, polystyrene, polyolefin, polyacrylate, poly(ethylene oxide), poly(ethyleneimine), polyester, polyurethane, polysiloxane, polyether, polyphosphazine, polyamide, polyimide, polyisobutylene, polyacrylonitrile, poly(vinyl chloride), poly(methylmethacrylate), poly(vinyl acetate), poly(vinylidene chloride), polytetrafluoroethylene, polyisoprene, polyacrylamide, polyacrylic acid, polymethacrylate, and polyacetals. 
     Formation 
     The sealant material of the present invention may be formed using several different techniques. Preferably, the sealant material or at least a portion thereof has a substantially homogeneous composition within itself. However, it is contemplated that various combining techniques may be used to increase or decrease the concentration of certain components in certain locations of the portions of the sealant material or the sealant material itself. 
     According to one embodiment, the sealant material can be formed by supplying the components of the material in solid form such as pellets, chunks and the like, in liquid form or a combination thereof. The components are typically combined in one or more containers such as large bins or other containers. Preferably, the containers can be used to intermix the components by rotating or otherwise moving the container. Thereafter, heat, pressure or a combination thereof may be applied to soften or liquidize the components such that the components can be intermixed by stirring or otherwise into a single homogenous composition. 
     According to another embodiment, the materials of the sealant material may be processed by heating one or more of the components that is generally easier to soften or liquidize such as the polymer based materials to induce those components into a mixable state. Thereafter, the remaining components may then be intermixed with the softened components. 
     For mixing, a variety of mixers or other devices may be employed. For example, such devices can include, without limitation, an internal mixer, a kneader, a mill, a single or twin screw extruder, a planetary mixer, a compounding extruder, combinations thereof or the like. 
     Application 
     The sealant material may be applied to a variety of substrates. However, for exemplary purposes and with no intention of limiting the invention unless otherwise stated, the material of  FIGS. 1A and 1B  is shown as applied to components  14 ,  16  (e.g., overlapping panels) for forming a joint. The joint, as shown, is formed with overlapping ends  24  of the two components  14 ,  16 . In one embodiment, the substrate is formed of a material that includes metal (e.g., steel, aluminum, iron, tin, magnesium, a combination thereof or the like), plastic (e.g., reinforced plastic), a combination thereof or the like. 
     As discussed, the sealant material  10  may be formed in a variety of shapes, sizes, patterns, thicknesses or the like and may be formed using a variety of forming techniques such as molding, extruding, thermosetting and the like. It is also contemplated that the sealant material or one of the portions thereof may be initially formed in a substantially liquid state wherein the material is shaped by its container or shaped by a substrate to which the material has been applied. 
     The sealant material may be dry to the touch shortly after it is initially formed to allow easier handling, packaging, application to a substrate and the like of the material, however, it is also possible for the material to be wet, tacky or both. As such, the sealant material may be placed adjacent a substrate either manually, automatically or semi-automatically. In one preferred embodiment, the sealant material is extruded directly onto the substrate that is to be sealed by the material. In another embodiment, the sealant material is manually applied as an insert. 
     In the embodiment illustrated in  FIG. 2 , the sealant material  10  is placed or located within the opening  30  (e.g., a cavity, ditch or recess) that is formed by the panels  14 ,  16 . In the particular embodiment illustrated, the opening  30  is a roof ditch of an automotive vehicle that is typically formed from body panels of the vehicle. As shown, the overlapping ends  24  of the panels  14 ,  16  at least partially define the opening  30  and the overlapping ends  24  form an interface  34  between the two panels  14 ,  16 . Typically, the interface  34  will define one or more gaps  36  between the overlapping ends  24  of the panels  14 ,  16 , even though effort is typically expended to minimize such gaps  36  for articles of manufacture such as automotive vehicles. 
     For sealing a substrate, the sealant material is typically placed upon the substrate adjacent to a target location that is to be sealed. Generally, it is contemplated that the target location of the substrate may be any type of opening of the substrate such as a cavity, a recess, a gap or the like or may be a flat or contoured portion of the substrate. 
     In  FIGS. 1A and 1B , the target location is the interface  34  and/or the one or more gaps  36  formed by the components  14 ,  16 . As can be seen, the sealant material  10  is placed or located overlaying and/or adjacent the interface  34  and the one or more gaps  36  formed by the interface  34 . 
     Once the sealant material has been formed in a desired configuration and located, as desired, relative to a substrate, the material may be activated to flow, expand, whet, seal, cure or a combination thereof to form a seal of a desired configuration. Activation of the sealant material, may take place in a single stage or multiple stages and may utilize a variety of stimuli to cause activation. Activation, as used herein, generally denotes inducing the sealant material to flow, generally soften, foam, expand, cure or a combination thereof and can be caused by exposure of the sealant material to a variety of stimuli such as heat, light, electricity, pressure, moisture and the like. Curing, as used herein, generally denotes any stiffening, hardening, solidifying or the like of the sealant material and can be caused by exposure to a variety of stimuli such as heat, cooling, light, moisture combinations thereof or the like. 
     According to one embodiment, the sealant material may be at least partially activated prior to application of the sealant material to a substrate such that the sealant material is in a generally flowable state when it is applied to the substrate. In such a situation, curing of the material may occur during or after the time the sealant material is applied to the substrate. 
     According to another embodiment, the sealant material may undergo a single stage activation, a single stage cure or both. According to still other embodiments, the sealant material may undergo a selective multiple stage activation, a multiple stage cure or both. For example, a portion of the sealant material may be exposed to a stimulus to at least partially cure a portion of the sealant material, e.g. a cure to a predetermined depth (e.g., on the order of about 1 mil to about 2 mm), or a cure in certain regions along or within the mass of material. 
     Upon activation, typically caused by exposure to heat or other stimulus, the first portion of the sealant material becomes more flowable than the second portion as previously described. Advantageously, this allows the first portion to flow over and seal the target location of the substrate while the second portion can maintain a surface suitable for various uses also previously described. 
     Additionally or alternatively, it is contemplated that a sealed joint prepared in accordance with the present invention can be further coated with a top coat (e.g., a paint) and optionally a primer (between the top coat and the joint), a clear coat (e.g., a polyurethane, an acrylic such as a glycidyl methacrylate (GMA)-based coating, or a mixture thereof) over the top coat, or a combination thereof. Preferably one such coating is a water-based coating, although solvent based coatings may also be used. In one embodiment, the coating includes a two component polyurethane coating. In another embodiment the coating is applied as a powder coating. Preferably an electrocoating process is used to apply a coating layer, such as an e-coat or other layer. 
     It is additionally or alternatively contemplated that the sealant material of the present invention may include a treated (e.g., a hardened or cured) surface. As can be seen in  FIG. 2 , there is illustrated an exemplary sealant material  50  that has at least one treated surface  52 . Typically, the sealant material  50  will be treated to a depth below the treated surface  52 , but such depth will typically depend upon the method of treating the surface  52 . 
     In one embodiment, the surface  52  is chemically treated to partially or fully harden or cure the surface  52 . For example, a curing agent, a curing agent accelerator or both may be coated (e.g., brushed, wiped, dripped, dabbed or the like) over the surface  52  of the material such that the surface cures and hardens. Exemplary curing agents could include amines, amides, acids, isocyanates, dicyandiamides, other curing agents or curing agent accelerators discussed herein or otherwise, combinations thereof or the like. Such partial or full curing or hardening will typically only extend to a shallow depth within the sealant material. 
     In another embodiment, the surface  52  is heat treated to partially or fully harden or cure the surface  52 . For example, an energy source may expose the surface  52  to energy or heat for a limited period of time for thereby curing and hardening the surface  52 . Exemplary energy sources, could in UV radiation sources (e.g., UV lamps), lasers, electromagnetic radiation sources, heating elements, combinations thereof or the like. Such partial or full curing or hardening will typically only extend to a shallow depth within the sealant material. 
     After or during treatment of the surface, the sealant material can be placed upon the substrate followed by activation and sealing of the sealant material as previously described. Prior to or during activation, the treated surface of the sealant material may be separated from the substrate by the remainder or thickness of the sealant material as shown in  FIG. 2  or it may be directly adjacent or contacting the substrate. The sealant material can be activated as previously described and the surface will typically remain rigid during such activation. Advantageously, the surface can assist in confining or otherwise controlling any flow of the sealant material. Moreover, the surface can prevent bubbles from flowing to and/or through the treated surface or to another surface and forming surface irregularities (e.g., bubbles or the like) thereon. 
     In another embodiment, it is contemplated that a hardened or cured surface may be formed on the sealant material by coating or spraying a surface of the material with an at least partially liquidized solution. Typically, the solution will harden or cure upon the surface of the sealant material for providing the treated (e.g., hardened or cured) surface. 
     It is also contemplated that the sealant material may include multiple portions of the same or different material, which may be formed by extrusion, co-extrusion, tri-extrusion or other techniques. In a preferred embodiment, the sealant material includes a separate portion that is relatively hard or rigid compared to the rest of the sealant material or does not become flowable like the rest of the sealant material upon activation. The separate portion may be formed of relatively rigid polymeric material such a polyethylene terphthalate (PET), a metal material such as a foil (e.g., aluminum foil), a fabric, a mesh combinations thereof or the like. 
     As one example, in  FIG. 3 , there is a sealant  60  having a separate portion shown as a film or layer  62  that is substantially entirely encapsulated or surrounded by sealant material  64 . Preferably, the sealant material  64  has been extruded about the film or layer  62 . As another example, in  FIG. 4  a sealant  70  is shown with a separate portion illustrated as a film or layer  72  that has been sandwiched between a first mass  74  and a second mass  76  of sealant material. Generally, it is contemplated that the sealants may be formed by pultrusion, extrusion (e.g., co-extrusion) or otherwise. 
     In another embodiment, a sealant is formed by providing a separate portion formed of a material similar to the sealant material, but which has been formulated to exhibit different characteristics than the sealant material. For example, the separate portion may have a viscosity, prior to or during activation of the sealant material, that is at least 10%, more typically at least 30% and even more typically at least 80% greater than the viscosity of the sealant material. As another example, the separate portion may be formulated so as to, upon activation, substantially entirely cure in an amount of time that is less that 90% more typically less than 80% and even more typically less than 60% of the amount of time that it takes for the sealant material to substantially entirely cure. In  FIG. 5  such a separate portion has been co-extruded as a film or layer  80  with a mass  82  of sealant material such that the film or layer  80  overlays the mass  82 . 
     Advantageously, the separate portions of the sealants described can assist in preventing bubbles from moving to and/or forming irregularities upon one or more surfaces of the sealant material. 
     It is also contemplated that the separate portion of the sealant material may have a more complex configuration. For example, in  FIG. 6 , there is illustrated a sealant  88  with a separate portion  90  that includes at least one, but preferably a pair of extensions  92  extending into an activatable portion  94  of the sealant  88 . 
     In another additional or alternative embodiment, the sealant material may be formulated such that the sealant material, upon activation, exhibits a particular surface or interfacial energy, a particular curing characteristic, a particular degree of whetting, a particular viscosity or a combination thereof. Advantageously, such formulations can assist the sealant material in purging gas or air (e.g., bubble) that nucleate through or purge from the sides of the sealant material. 
     As one example, the sealant material is formulated such that the surface energy of sealant material, upon activation or in its softened, melted or flowable state, is relatively close to the surface energy of the substrate to which the sealant material has been applied. In such an embodiment, the surface energy of the sealant material is typically no more than 50% greater or less, more typically no more than 25% greater or less and even more typically not more than 10% greater or less than the surface energy of the substrate for purposes of clarification, a quantity of 110 is 10% greater than a quantity of 100 and a quantity of 90 is 10% less and like calculating may be made for other values. Ingredients which can assist the sealant material in attaining a desired surface energy include, without limitation, particulated polymeric materials such as particulated polytetrafluoroethylene (PTFE). 
     In  FIG. 7 , a sealant material  100  is formulated such that its activation surface tension is relatively close to the surface energy of the substrate, which as shown are the panels  14 ,  16  that are preferably covered by e-coat. As depicted, a bubble  102  has formed during activation, upon the panel  14  between the sealant material  100  and the panel  14 . Advantageously, since the surface tensions of the sealant material  100  and the panel  14  are relatively close to each other, the interfacial tension between the panel  14  and the sealant material  100  is lower than any interfacial tension between the bubble  102  and the panel  14 , the bubble  102  is more likely to nucleate through or out by the sides of the sealant material  100  at a faster rate thereby purging the bubble prior to cure of the sealant material  100 . As such, the bubble  102  is less likely to be caught upon or below a surface  104  of the material  100  and form any surface irregularities. 
     The sealant material may also be formulated to have a relatively low viscosity upon activation for a desired period of time thereby assisting in more rapid nucleation or expulsion of bubbles from the sealant material. Generally, the desired period of time is an amount of time long enough to purge the bubbles from the sealant material but short enough to prevent the sealant material from flowing to undesirable locations (e.g., off of the substrate). In such an embodiment, the sealant material, upon activation, will typically maintain its viscosity below about 10,000 centipoise for a period of time between about 5 seconds and about 20 minutes, more typically below about 5,000 centipoise for a period of time between about 15 seconds and about 5 minutes and even more typically below about 1000 centipoise for a period of time between about 30 seconds and 2 minutes. 
     Achieving such a relatively low viscosity can be accomplished by including one or more thermoplastics (e.g., polyamides), one or more waxes, one or more thermoplastic waxes, a combination thereof or the like in the sealant material. In one embodiment, the sealant material has a cure profile such as that modeled in  FIG. 8  upon exposure to a stimulus such as heat. In  FIG. 8 , the sealant material is exposed to heat (e.g., by entry into an e-coat or paint oven) and remains substantially uncured for a first period of time  110  followed by experiencing a substantially full cure over a second relatively short period of time  112 . Preferably, the sealant material reaches its relatively low viscosity for a desired period of time during the first period of time. 
     One method of accomplishing a cure profile similar to that in  FIG. 8  is by providing the sealant material with an encapsulated curing agent, curing agent accelerator or both. For example, a curing agent, a curing agent accelerator or both may be encapsulated in a thermoplastic shell wherein the shell melts upon exposure to the heat (e.g., in the e-coat or paint oven) over a period of time (e.g., the first period of time  110 ) such that curing of the sealant material is essentially or substantially delayed for that period of time. However, after the melting of the thermoplastic shell or encapsulation, the curing agent, the curing agent accelerator or both can cure the sealant material over a second period of time (e.g., the second relatively short period of time  112 ). 
     In still other alternative or additional embodiments, it is contemplated that the sealant material may be formed in a variety of shape, sizes and configurations. Moreover, the sealant material may be located in variety of locations relative to the substrate to which it is applied. 
     In one embodiment, the sealant material of the present invention is applied to overlapping panels that form an interface. In  FIGS. 9-11 , strips of sealant material are applied to the overlapping panels  14 ,  16  that form the roof ditch such as was previously discussed. As shown, the strips are generally circular in cross-section, but may be configured as needed or desired. In each Figure, there is a first or upper panel  14  having an end portion  24  that overlaps an end portion  24  of the second or lower panel  16 . In  FIG. 9 , a strip  120  of sealant material is located upon the first panel  14  and, upon activation, the strip  120  becomes flowable and flows over the interface  34  between the panels  14 ,  16  and contacts and whets the second panel  16  and then cures to seal the interface  34 . 
     In  FIG. 10 , a strip  124  of sealant material is located upon the second panel  16  and, upon activation, the strip  124  becomes flowable and flows over the interface  34  between the panels  14 ,  16  and contacts and whets the first panel  14  and then cures to seal the interface  34 . In  FIG. 11 , there is a first strip  130  of sealant material located upon the first panel  14  and the a second strip  132  of sealant material located upon the second panel  16 . Upon activation, the first and second strip  130 ,  132  flow toward the interface  34  and converge upon each other to seal over the interface. Typically the embodiments of  FIGS. 9-10  assist in allowing air to be purged away from the interface  34  at an earlier stage or more effectively during flow of the sealant material such that bubbles are less likely be trapped by the sealant material and/or form surface irregularities on the sealant material. 
     In  FIG. 12 , the two strips  130 ,  132  as shown in  FIG. 11  are interconnected by an intermediate member  134 , which may be formed of the sealant material or another material. Typically, the strips  130 ,  132  of  FIG. 12  operate to seal the interface as in  FIG. 11 , however, the member  134  can maintain a desired spacing between the strips  130 ,  132  during placement of the strips  130 ,  132  in the roof ditch and/or upon the panels  14 ,  16 . 
     In another additional or alternative embodiment, the sealant material may be attached to a trim piece or other component such that the trim piece or other component and the sealant material can be assembled to a substrate together. In  FIG. 13 , a strip  140  of sealant material is attached (e.g., adhered) to a surface  142  of a trim piece  144  and the trim piece  144  and strip  140  can be assembled together into the roof ditch  30  and onto one or both of the panels  14 ,  16 . In such an embodiment, fasteners (e.g., adhesives or mechanical fasteners, spots of fast curing sealant material, combinations thereof or the like) may be used to hold the trim piece in place during activation of the strip  140  of sealant material such that the sealant material can cure and adhere to the surface  142  of the trim piece  144  and the panels  14 ,  16 . Preferably, the trim piece  144 , the sealant material or both are paintable (e.g., in a traditional automotive paint oven). 
     In still another additional or alternative embodiment, the sealant material may include pieces (e.g., flakes, powder, chunks, fibers, spheres, platelets, combination thereof or the like) of blocking material for preventing bubbles from penetrating through the sealant material to an outwardly facing surface of the sealant material. Preferably, the pieces of material remain substantially solid during flow of the sealant material such that bubbles or air cannot penetrate to the pieces. For example, in  FIG. 14 , pieces  150  of blocking material, which may be flakes, chunks, powder or the like, are coated as a layer  152  over a surface of an activatable portion  154  of a sealant material  156  such that the layer  152  can prevent penetration of bubbles therethrough to a outwardly facing surface  158  of the layer  152  and/or sealant material  156 . As another example, in  FIG. 15 , pieces  160  of blocking material, shown as flakes, are interspersed throughout an activatable portion  162  of a sealant material  164  such that bubbles are prevented from penetrating through the sealant material  164  to an outwardly facing surface  166  thereof. Exemplary materials, which may be used to form the pieces of blocking material include polyethyleneterephthalate (PET), polyamides, glass, porous glass, ceramic, nanocomposites, nanoparticles, carbon black, feathers or the like, however, many other material may be used as well. 
     In another additional or alternative embodiment, it is contemplated that the sealant material may include a magnetic material. For example, a magnetic material such as magnetic flakes, powders, particles or the like may be included in the sealant material. Preferred magnetic particles for use in the present invention are ferrites, such as barium ferrite and strontium ferrite. Also preferred are iron oxides. One particularly preferred type of magnetic particle for use in the present invention is sold under the tradename HM406 “Starmag” ceramic powder, commercially available from Hoosier Magnetics, Inc., 65 Main Street, Postsdam, N.Y. 13676. The particle size of the magnetic particles is preferably between about 0.1 and 100 microns in diameter and more preferably from about 1 to about 10 microns, with the average magnetized particle size being preferably from about 0.5 to 10 microns, e.g., about 2 to about 5 microns. Advantageously, the magnetic material can assist in holding the sealant material in place upon a metal substrate (e.g., roof ditch panels) prior to, during and possibly after activation of the sealant material. 
     In other additional alternative embodiments, it is contemplated that the sealant material may be designed to have a relatively small contact surface for contacting a first portion of a surface of a substrate for supporting the sealant material on the substrate prior to activation of the sealant material. Typically, such a sealant material is additionally configured to, upon activation, flow and contact one or more additional second portions of the surface of the substrate progressively outward from the first portion. Typically, the second portions of the surface are at least 50%, more typically at least 100%, even more typically at least 150% and still more typically at least 200% of the amount of surface area represented by the first portion. 
     As an example, in  FIG. 16 , there is illustrated a sealant material  170  having a central portion  172  with an initial contact surface  174  which is contacting a first portion  176  of a surface  178  of one or both of the panels  14 ,  16  forming a roof ditch. As shown, the sealant material  170  has a generally U-shape cross-section with a first flange  180  and surface  187  cantilevered over one second portion  188  of the surface  174  and a second flange  190  and surface  192  cantilevered over another second portion  188  of the surface  174 . Upon activation of the sealant material, the flanges  180 ,  190  are typically progressively lowered such that the surfaces  182 ,  192  progressively contact the second portions  188  of the surface  174 . 
     Other embodiments, which may seal in a similar manner to that of the sealant material of  FIG. 16  are illustrated in  FIGS. 16A-16C . In  FIG. 16A  there is illustrated a sealant material  200  with an initial contact surface  202  and a cross-section that is a truncated triangle or trapezoid. In  FIG. 16B , there is illustrated a sealant material  210  with an initial contact surface  222  and a circular cross-section. In  FIG. 16C , there is illustrated a sealant material  220  with an initial contact surface  222  and a triangular cross-section. Advantageously, such embodiments can assist the sealant materials in purging air to the sides of the sealant material upon activation. 
     In yet another additional or alternative embodiment shown in  FIG. 17 , there is illustrated a sealant material  230  composed of multiple strands  232  (e.g., 2, 3, 4 or more) which are woven together, for instance, in a licorice-like or braided configuration. It is believed that such an embodiment provides multiple passageways for air to be purged from the sealant material upon activation thereof. 
     Generally, it is contemplated that for any of the embodiments discussed herein, a fastener (e.g., a mechanical fastener, an adhesive, a tape or the like) may be employed to at least temporarily hold the sealant material in place until activation. For example, a tape (e.g., a pressure sensitive or double sided tape) may be employed to at least temporarily adhere the sealant material to a substrate. Such a tape may be used at ends (e.g., adjacent A, C or D pillars for an automotive vehicle) of the sealant material or at middle portions of the sealant material and may be employed to hold the sealant material in place, restrict flow of the sealant material or both. 
     In one embodiment, it is contemplated that the sealant material may be tacky or pressure sensitive and may be provided upon a release film or release tape. In such and embodiment, an individual or machine could handle or contact the release film or tape in a manner that allows one side of the sealant material to be contacted and adhered to a substrate. Thereafter, the release film or tape can be removed from the sealant material and the sealant material will be held in place by tackiness of the sealant material. In such an embodiment, it may be preferable to provide the sealant material as a roll with the release tape thereon such that the sealant material can be rolled onto the substrate. 
     Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. Plural structural components can be provided by a single integrated structure. Alternatively, a single integrated structure might be divided into separate plural components. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. 
     The preferred embodiment of the present invention has been disclosed. A person of ordinary skill in the art would realize however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention.