WO2017176832A1

WO2017176832A1 - High strength weldable structural tape

Info

Publication number: WO2017176832A1
Application number: PCT/US2017/026058
Authority: WO
Inventors: Phoebe ZHOU
Original assignee: Zephyros, Inc.
Priority date: 2016-04-06
Filing date: 2017-04-05
Publication date: 2017-10-12
Also published as: CN107262970A

Abstract

A weldable adhesive or sealant formulation comprising a structural tape including a solid rubber, a liquid rubber, a tackifier, and an epoxy, wherein the tape is weldable and substantially free of any fibrous filler and includes less than about 20% of any conductive filler.

Description

HIGH STRENGTH WELDABLE STRUCTURAL TAPE

FIELD OF THE INVENTION

[0001] The present teachings relate generally to weldable sealants and adhesives. More specifically, the present teachings relate to sealants and adhesives including a rubber component, a tackifier component, and a minimal amount (e.g., 20% by weight or less) of a solid metallic component.

BACKGROUND OF THE INVENTION

[0002] Weldable sealant and adhesive formulations often utilize conductive fillers (e.g., carbon black, iron phosphide, graphite, iron powder, nickel powder, and the like) that result in the sealants/adhesives having a relatively narrow region of green state (e.g., pre-activation) viscosity. Lower viscosity allows the sealant/adhesive material to "squeeze-out" of the spot weld "tip" area between substrates thus enabling the conductive fillers to bridge the gap between the substrates to provide the low resistance required for proper resistance welding. Alternatively, higher green state viscosities tend to improve the mechanical properties of the sealant/adhesive post-cure as well as improving processing, handling and packaging requirements. However, sealants/adhesives with this higher green-state viscosity have less of an ability to "squeeze-out" sufficiently to allow the metal substrates to engage the conductive fillers. Further, exposure of such adhesives and sealants to low temperatures may also cause an increase in viscosity, presenting challenges to weldability and a reduction in tack strength and adhesion.

[0003] Further, conductive fillers typically used in the sealant/adhesive field for improving the weldability may be unintentionally encapsulated by non-conductive polymeric materials, wetting agents, plasticizers and the like within the adhesive or sealant composition, that are used to provide strength and corrosion resistance. These encapsulations of the conductive fillers inhibit and/or limit the material from being "conductive" in its supplied form. Only during the pressure applied by the resistance welding and the displacement of the adhesive/sealant from the applied pressure (if the pressure and displacement are sufficient) does the material become thin enough to engage the conductive materials to provide for a sufficient weld condition.

[0004] Various non-conductive fibrous materials (e.g., cellulose, Kevlar, polyethylene, glass, etc.) are also commonly used in sealant/adhesive formulations. In the green state, fibers provide flow control, dimensional stability, extrusion die swell control and cracking resistance to the sealant/adhesive. Unfortunately, during welding, these nonconductive fibers have a tendency to prevent the sealant/adhesive material from moving away or adequately "squeezing-out" during the applied pressure from the spot weld. Furthermore, the fibers may prevent adequate bridging of the gap between the weld substrates, thus, detrimentally increasing the electrical resistance. Conductive fibers, such as carbon fiber may help to remedy some of these issues, but they tend to be expensive and fragile to the mixing and forming processes. Nickel coated glass spheres improve electrical conductivity well at high loading levels but will crush under the applied pressure of a spot/resistance weld which detrimentally breaks up the conductive path needed for a proper spot/resistance weld.

[0005] It would thus be desirable to provide a sealant/adhesive formulation that overcomes the issues identified above to make a material that has high-strength and improved adhesion and tackiness at low temperatures, along with an appropriate viscosity to allow for displacement to form a highly weldable material.

SUMMARY OF THE INVENTION

[0006] The present teachings meet some or all of the above needs by providing for a formulation that is formed into a structural tape comprising an adhesive/sealant formulation. The adhesive formulation includes a solid rubber, a liquid rubber, and an epoxy, wherein the tape is weldable and substantially free of any fibrous filler and includes less than about 20% of any conductive filler. The adhesive may include a tackifier. The liquid rubber may be present in an amount of at least about 1 %, at least about 2%, at least about 3% or even at least about 4%. The liquid rubber may be present in an amount of less than about 10%, less than about 7%, or even less than about 5%. The epoxy may be a solid epoxy, a semi-solid epoxy, a liquid epoxy, or any combination thereof. The epoxy may include at least about 5%, at least about 10%, at least about 20% or even at least about 25% of a liquid epoxy resin. The epoxy may include at least about 5%, at least about 10%, or even at least about 20% of a solid epoxy resin. The epoxy may include at least about 1 %, at least about 3%, or even at least about 5% of a semi-solid epoxy resin. The tape may include less than 15% of any conductive filler. The tape may include a non-conductive filler. The tape may include at least about 4%, at least about 6%, at least about 8%, or even at least about 10% of a non-conductive filler. A 2mm thickness of the tape exposed to oven bake temperatures of at least about 165°C has a resulting sag of less than 1 mm, less than 0.8 mm, or even less than 0.5 mm. The tape may be substantially free of any core/shell component. The tape may have a viscosity of at least 8 Nm and not higher than 28 Nm with Torque Rhemoter test (XSS-300) under such conditions of 40 rpm at 60°C. The ratio of liquid rubber to solid rubber may be from about 2:1 to about 1 :2. The ratio of liquid rubber to solid rubber may be about 1 : 1 . The ratio of liquid rubber to solid rubber may be about 4:5. The tackifier may be included in the adhesive in an amount of from about 0.2% to about 10% of the adhesive. The tack of the adhesive including a tackifier may increase by at least 1000% percent as compared to the adhesive without the tackifier. The tack of the adhesive including a tackifier may increase by at least 3000% percent as compared to the adhesive without the tackifier.

[0007] The teachings herein provide for a sellable sealant formulation having a relatively low amount of conductive filler (e.g., about 15% or less) and a viscosity allowing for sufficient movement during spot welding while maintaining minimal sag.

DETAILED DESCRIPTION

[0008] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the teachings, its principles, and its practical application. Those skilled in the art may adapt and apply the teachings in its numerous forms, as may be best suited to the requirements of a particular use. Accordingly, the specific embodiments of the present teachings as set forth are not intended as being exhaustive or limiting of the teachings. The scope of the teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. Other combinations are also possible as will be gleaned from the following claims, which are also hereby incorporated by reference into this written description.

[0009] This application claims the benefit of the filing date of Chinese patent Application No. 201610210673.9, filed April 6, 2016, the entirety of the contents of that application being hereby incorporated by reference herein for all purposes.

[0010] The teachings herein utilize a combination of liquid and solid rubbers with a multi functional epoxy material to produce a weldable sealant that maintains high strength and minimal sag while still having a viscosity that is sufficiently low so that the sealant moves as needed during welding. The adhesive/sealant compositions described herein may also be formulated with a tackifying component in order to improve the overall adhesion of the material upon activation and cure while minimizing any deleterious effects on weldability and sag.

[0011] The sealant material (which may be referred to herein as an adhesive or tape) according to the teachings herein include one or more rubber components. The rubber may be in liquid form or in solid form. The rubber may be supplied in both liquid form and solid form. The rubber may be any rubber that allows the epoxy resin to retain some ductility (i.e., reduce the brittleness of the adhesive), toughness, or both before curing, after curing, or both. The rubber may allow the adhesive to elongate without breaking, cracking, fracturing, becoming unattached to one of the surfaces, or a combination thereof. Some rubbers that may be used are: carboxyl terminated butadiene acrylonitrile (CTBN), carboxyl terminated butadiene (CTB); core shell, polybutadiene, polybutadiene with maleic anhydride, or a combination thereof. The rubber may be non-reactive with the epoxy resins. An example of a nonreactive rubber- containing component is Kane Ace MX 136 available from Kaneka. Kane Ace MX 136 is a dispersion consisting of 25% by weight core shell rubber based on polybutadiene with 75% by weight liquid epoxy resin based on Bisphenol F. The rubber may have reactive groups that can react with epoxy resins. An example of a rubber with groups that can react with epoxide groups is a carboxyl terminated butadiene acrylonitrile (CTBN) rubber. The CTBN rubber may be mixed into the epoxy resin using elevated temperature and possibly a catalyst such as triphenylphosphine to create a reaction component. The epoxy may include about percent by weight or more rubber, about 15 percent by weight or more rubber, or preferably about 25 percent by weight or more rubber. The epoxy may include about 45 percent by weight or less, about 35 percent by weight or less, or about 30 percent by weight or less rubber (i.e., about 30 percent by weight rubber). The epoxy may include between about 20 percent by weight and about 30 percent by weight rubber. The total composition may include about 3 percent by weight or more, about 5 percent by weight or more, or about 7 percent by weight or more rubber (i.e., about 7.5 percent by weight rubber). The total composition may include between about 2 percent by weight and about 15 percent by weight or about 5 percent by weight and about 10 percent by weight rubber. The reaction component may be referred to herein as part of the epoxy. For example, the rubber may be mixed into a resin and then the amount of rubber added to the composition may be recited by one of the weight percentages of epoxy recited herein However, the amount of rubber added to the adhesive may be a sufficient amount so that the adhesive includes ductility, toughness, or both. The amount of rubber added may be a sufficient amount so that the cured adhesive has an elongation of about 1 percent or more, about 2 percent or more, or even about 2.5 percent or more. The amount of rubber added may be a sufficient amount so that the cured adhesive has an elongation of between about 1 percent and about 10 percent, preferably about 2 percent and about 7 percent, or more preferably between about 2.5 percent and about 6 percent.

[0012] The adhesive/sealant may be substantially free of any fibrous fillers. The lack of such fibrous fillers may aid in maintaining a sufficiently low viscosity to allow for displacement during a welding process.

[0013] Epoxy resin is used herein to mean any of the conventional epoxy materials containing at least one epoxy functional group. The epoxy resin may be any epoxy resin that may be used to adhere two or more materials together. The epoxy resin may be any epoxy resin so that the epoxy resin once cured adheres two or more materials together and allows the cured adhesive to be less brittle. In addition, a rubber component may be included with the epoxy to provide for an adhesive where the resulting adhesive is less brittle than it would be in the absence of the rubber component. The epoxy resin may be any epoxy resin that adheres to metal and glass and may withstand temperature and humidity variations. The epoxy resins may be difunctional, trifunctional, multifunctional, or any combination thereof. Moreover, the term epoxy resin can be used to denote one epoxy resin or a combination of multiple epoxy resins. The epoxy resin may be a solid epoxy or a liquid epoxy. The adhesive material may include about 5 percent by weight epoxy or more, preferably about 15 percent by weight epoxy or more, more preferably about 25 percent by weight or more, even more preferably about 40 percent by weight epoxy or more, or most preferably about 50 percent by weight epoxy or more. The adhesive material may include about 90 percent by weight epoxy or less, about 85 percent by weight epoxy or less, or about 80 percent by weight epoxy or less. The adhesive material may include between about 20 percent and about 85 percent by weight epoxy resin, preferably between about 45 percent and about 80 percent by weight epoxy resin, and more preferably between about 50 percent and about 78 percent by weight epoxy resin. As discussed, the percentage epoxy resin by weight includes both solid and liquid epoxy. As an example, it is contemplated that weight percentages may be lower or higher when other ingredients such as elastomers, impact modifiers, crosslinking agents, fillers, alternative polymers, and combinations thereof, are used in greater or lesser weight percentages.

[0014] The epoxy may be aliphatic, cycloaliphatic, aromatic, or the like. The epoxy may be supplied as a solid (e.g., as flakes or pellets) or a liquid or both. An epoxy resin is added to the adhesive material to create a thermoset and to increase the adhesion, flow properties, or both, of the material. As an example, the epoxy resin may be a phenolic resin, which may be a novalac type or other type resin. For example, bisphenol A resin, bisphenol F resin, or a combination thereof may be employed. Moreover, various mixtures of several different epoxy resins may be employed as well. The epoxy resin may be a reaction product of epichlorohydrin and bisphenol A. The epoxy resin may include a diglycidyl ether of bisphenol A.

[0015] The epoxy resin may be comprised of about 20% or more, more typically about 30% or more and even possibly about 40% or more by weight thereof of liquid epoxy resin (e.g. a resin that has a molecular weight such that it is liquid at 23° C). The epoxy resin may be comprised of about 100% or less, about 90% or less, or preferably about 80% or less by weight liquid epoxy resin. Such liquid epoxy resin typically has a viscosity at a temperature of 23° C. of about 5 Pa s or more and typically about 22 Pa s or less, although higher and lower values may also be possible. The liquid epoxy resins may include diglycidyl ethers (bisphenol A or F) such as those commercially available from the Kukdo Chemical Co. Ltd. The liquid epoxy resins may be epoxy phenol novolac based such as those commercially available from Kukdo Chemical Co. Ltd.

[0016] The adhesive/sealant may include a solid epoxy and a liquid epoxy. The ratio of solid epoxy to liquid epoxy may be any ratio so that when the green adhesive including the epoxy mixture and the second surface are applied to the first surface, the second surface and/or the adhesive do not move along the first surface, fall off the first surface, or both. The ratio of solid epoxy to liquid epoxy may be any ratio so that the viscosity of the green adhesive is low enough so that the adhesive may be evenly applied to a surface. The ratio of solid epoxy to liquid epoxy may be any ratio so that the green state adhesive holds the first surface and the second surface static relative to each other before curing, during curing, or both. The ratio of solid epoxy to liquid epoxy may be about 1 : 1 or greater, about 1 .2: 1 or greater, or about 1 .4: 1 or greater. The ratio of solid epoxy to liquid epoxy may be about 1 :2 or less, about 1 : 1 .5 or less, or about 1 : 1 .2 or less. The ratio of solid epoxy to liquid epoxy is between about 1 : 1 and about 3:1 and may be between about 1 .2:1 and about 2.5: 1 .

[0017] The metallic filler may comprise carbon steel, titanium, aluminum, brass, iron, stainless steel, bronze, copper, chrome steel, tin, or any conductive material. The discrete metallic portions may comprise a material with a coating. For example, the coating may be a material that assists in avoiding corrosion of the conductive material.

[0018] The metallic filler may be solid. They may be hollow. The solid metallic portions may have a largest diameter of at least about 0.10mm. The solid metallic portions may have a largest diameter of at least about 0.20mm. The solid metallic portions may have a largest diameter of at least about 0.30mm. The solid metallic portions may have a largest diameter of less than about 2.5mm. The solid metallic portions may have a largest diameter of at least about 1 .0mm. The solid metallic portions may have a largest diameter of at least about 0.50mm. [0019] The metallic filler may be present in an amount of at least about 1 % by volume of the formulation. The solid metallic portions may be present in an amount of at least about 2% by volume of the formulation. The solid metallic portions may be present in an amount of at least about 5% by volume of the formulation. The solid metallic portions may be present in an amount of at least about 10% by volume of the formulation. The solid metallic portions may be present in an amount of less than about 30% by volume of the formulation. The solid metallic portions may be present in an amount of less than about 20% by volume of the formulation. The solid metallic portions may be present in an amount of less than about 15% by volume of the formulation. The volume percentage of the solid metallic portions may vary based upon the thickness of the adhesive or seal material and the area covered.

[0020] The tackifier may be selected from a material that improves the adhesive properties of the adhesive/sealant. Non-limiting examples include rosin esters, polyterpene resins and hydrocarbon resins. An exemplary hydrocarbon resin material is 1 ,3-pentadiene polymer with 2-methyl-2-butene available from ATP Elastomers, Akron, OH. The tackifier may be a polyterpene resin, manufactured by Kraton Corporation, Almere, Netherlands. The tackifier may be a rosin ester manufactured by Kraton Corporation, Almere, Netherlands. The amount of tackifier present in the total adhesive/sealant composition may be from about 0.1 % by weight to about 5% by weight. The amount of tackifier present in the total adhesive/sealant composition may be from about 0.5% to about 3%.

[0021] The formulation described herein allows for the weldability or improved weldability of adhesive and sealant formulations having higher viscosities than would traditionally be weldable. The formulations described herein may have a viscosity at room temperature of greater than 30,000 Pa s. The formulations described herein may have a viscosity at room temperature of greater than 40,000 Pa s. The formulations described herein may have a viscosity at room temperature of greater than 50,000 Pa s. The formulations described herein may have a viscosity at room temperature of greater than 60,000 Pa s. The formulations described herein may have a viscosity at room temperature of greater than 70,000 Pa s. The formulations described herein may have a viscosity at room temperature of greater than 80,000 Pa s. [0022] The adhesive or sealant material described herein may pass shunt weld testing for metal to metal welding (with the material described herein located therebetween) by having resulting cycle loss of less than 2.0 or even less than 1 .0 for welding that occurs anywhere between 2 inches to 6 inches from the shunt.

[0023] In general, the teachings herein provide for a weldable sealant or adhesive material that includes a plurality of discrete solid metallic portions, whereby the sealant or adhesive material can have a higher viscosity than traditional weldable materials dues to the presence of the discrete metallic portions and their ability to create nodes for improved weldability.

[0024] The adhesive or sealant may be structural in nature. Alternatively, the adhesive may be an elastic adhesive or sealant material. Accordingly, the resulting material may be a structural or may be a sealing material. The material may be formed as a tape.

[0025] The adhesive or sealant may likely include epoxy materials that are blended or pre-reacted in adduct form in various ratios. These materials may be formulated with polymerization and cross-linking schemes commensurate with typical epoxy chemistries. The adhesive or sealant may also include low odor and/or non-flammable polymeric materials. The adhesive or sealant may further include one or more materials for promoting adhesion and one or more materials to act as curing agents. Various polymeric materials may be included such as rubber materials, thermoplastic materials (polyethylene, polyurethane), impact modifiers, and the like. Additional materials may also be included in the adhesive or sealant including but not limited to antioxidants, stabilizers, solvents, initiators and crosslinkers.

[0026] The adhesive or sealant may further include one or more impact modifiers for improving the toughness of the adhesive or sealant. The impact modifiers may be present in an amount of at least 1 %, at least 5%, at least 10%, at least 20% or even at least 25% by weight of the total adhesive or sealant composition. The impact modifiers may be present in an amount of less than 40%, less than 30%, less than 20%, or even less than 10% by weight of the total adhesive or sealant composition. A structural material may include from about 5% to about 20% by weight of impact modifiers. An elastic material may include from about 15% to about 30% by weight of impact modifiers. [0027] The adhesive or sealant may further include any number of toughening agents, stabilizers, catalysts, adhesion promoters and/or fillers. Any one, or any combination of these additional materials may be present in an amount of at least 2%, at least 5%, at least 10% or even at least 15% by weight of the composition. Any one, or any combination of these additional materials may be present in an amount of less than 20%, less than 15%, or even less than 10% by weight of the composition. A structural material may include from about 5% to about 15% by weight of one or any combination of these additional materials. An elastic material may include from about 5% to about 10% by weight of one or any combination of these additional materials.

[0028] The adhesive/sealant may include an impact modifier. The adhesive/sealant may be substantially free of any impact modifier. The impact modifier, if present, may include one or more core/shell polymers. As used herein, the term core/shell polymer describes an impact modifier wherein a substantial portion (e.g., greater than 30%, 50%, 70% or more by weight) thereof is comprised of a first polymeric material (i.e., the first or core material) that is substantially entirely encapsulated by a second polymeric material (i.e., the second or shell material). The first and second polymeric materials, as used herein, can be comprised of one, two, three or more polymers that are combined and/or reacted together (e.g., sequentially polymerized) or may be part of separate or same core/shell systems. The first polymeric material, the second polymeric material or both of the core/shell impact modifier include or are substantially entirely composed of (e.g., at least 70%, 80%, 90% or more by weight) one or more thermoplastics. Exemplary thermoplastics include, without limitation, styrenics, acrylonitriles, acrylates, acetates, polyamides, polyethylenes or the like. It may be desirable for the glass transition temperature of the first or core polymeric material to be below 23 °C while the glass temperature of the second or shell polymeric material to be above 23 °C, although not required.

[0029] Examples of useful core-shell graft copolymers are those where hard containing compounds, such as styrene, acrylonitrile or methyl methacrylate, are grafted onto core made from polymers of soft or elastomeric containing compounds such as butadiene or butyl acrylate. U.S. Pat. No. 3,985,703, which is herein incorporated by reference, describes useful core-shell polymers, the cores of which are made from butyl acrylate but can be based on ethyl isobutyl, 2-ethylhexyl or other alkyl acrylates or mixtures thereof. The core polymer, may also include other copolymerizable containing compounds, such as styrene, vinyl acetate, methyl methacrylate, butadiene, isoprene, or the like. The shell portion may be polymerized from methyl methacrylate and optionally other alkyl methacrylates, such as ethyl, butyl, or mixtures thereof methacrylates. Examples of core-shell graft copolymers include, but are not limited to, "MBS" (methacrylate-butadiene-styrene) polymers, which are made by polymerizing methyl methacrylate in the presence of polybutadiene or a polybutadiene copolymer rubber. The MBS graft copolymer resin generally has a styrene butadiene rubber core and a shell of acrylic polymer or copolymer. Examples of other useful core-shell graft copolymer resins include, ABS (acrylonitrile-butadiene-styrene), MABS (methacrylate- acrylonitrile-butadiene-styrene), ASA (acrylate-styrene-acrylonitrile), all acrylics, SA EPDM (styrene-acrylonitrile grafted onto elastomeric backbones of ethylene-propylene diene monomer), MAS (methacrylic-acrylic rubber styrene), and the like and mixtures thereof.

[0030] The adhesive or sealant may also include one or more additional polymer and/or copolymer materials, such as thermoplastics, elastomers, plastomers, combinations thereof or the like. The adhesive or sealant may include polyurethanes. Polymers that might be appropriately incorporated into the adhesive or sealant include epoxies. Combinations of epoxies and polyurethanes may be utilized. Combinations of epoxies and acrylates (e.g., methacrylates) may be utilized. Silane-modified polymers may be included.

[0031] One or more additional polymeric materials may be included. Such polymeric materials may include but are not limited to halogenated polymers, polycarbonates, polyketones, urethanes, polyesters, silanes, sulfones, allyls, olefins, styrenes, acrylates, methacrylates, silicones, phenolics, rubbers, polyphenylene oxides, terphthalates, acetates (e.g., EVA), acrylates, methacrylates (e.g., ethylene methyl acrylate polymer) or mixtures thereof. Other potential polymeric materials may be or may include, without limitation, polyolefin (e.g., polyethylene, polypropylene) polystyrene, polyacrylate, poly(ethylene oxide), poly(ethyleneimine), polyester, polysiloxane, polyether, polyphosphazine, polyamide, polyimide, polyisobutylene, polyacrylonitrile, polyvinyl chloride), poly(methyl methacrylate), polyvinyl acetate), poly(vinylidene chloride), polytetrafluoroethylene, polyisoprene, polyacrylamide, polyacrylic acid, polymethacrylate.

[0032] The adhesive or sealant may include a curing agent (e.g., an initiator). Examples of suitable curing agents include materials selected from aliphatic or aromatic amines or their respective adducts, amidoamines, polyamides, cycloaliphatic amines, anhydrides, polycarboxylic polyesters, isocyanates, phenol-based resins (e.g., 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 or polyamides such as triethylenetetramine, diethylenetriamine tetraethylenepentamine, cyanoguanidine, dicyandiamides and the like. The curing agent may be a peroxide or sulfur curing agent. An accelerator for the curing agents (e.g., a modified or unmodified urea such as methylene diphenyl bis urea, an imidazole or a combination thereof) may also be provided for preparing the adhesive or sealant.

[0033] The adhesive or sealant material may cure at room temperature with no additional stimulus. The adhesive or sealant material may undergo an induction cure, a microwave cure, an ultra-violet activated cure, or a moisture cure, any of which may occur at room temperature or at an elevated temperature. The adhesive or sealant may cure via a redox reaction cure system. The adhesive or sealant material may comprise a two-component cure system wherein cure occurs upon mixing of the two-components. Typically, the adhesive or sealant material cures at temperatures in the range of about 15°C to about 40°C.

[0034] During manufacture, the adhesive or sealant material may be formed in its green state by die-cutting, extrusion, injection molding, calendaring, hand shaping, or by means of gravity. The discrete metallic portions may be located onto an extruded adhesive or sealant and then calendar rolled and pressed into the material to prevent exposure of the metallic portions that could cause corrosion.

[0035] Examples [0036] Example formulations 1 through 4 in accordance with the teachings herein are set forth at Table 1 below. Formulation 4 is prepared according to the teachings herein, but is formulated without a tackifier.

[0037] Table 1

[0038] Test Results

[0039] Testing specimens are prepared as a smooth-surfaced adhesive sample in accordance with the present teachings supported by a clean metal coupon (0.025m x 0.1 m). The area covered by the adhesive is (0.025m x 0.025m). Prior to testing, the adhesive and coupon are conditioned at 0°C for 3 hours in an effort to mimic cold weather conditions. A test specimen is then clamped into a tension testing device. A cooled coupon is set by a grip as a probe at a distance of 0.5 mm from the test specimen. The probe should be large enough to cover the area of the adhesive. At a speed of 1 mm/s, the probe is then brought into contact with the adhesive until the contact force is 3 N. After a contact time of 15 seconds, the probe is separated from the adhesive at a speed of 10 mm/s. The tack of the specimens is recorded as the maximum force in Newtons to separate the probe from the adhesive. Test results of each of the example formulations set forth above are shown at Table 2 below.

[0040] Table 2

[0041] Any numerical values recited herein include all values from the lower value to the upper value in increments of one unit provided that there is a separation of at least 2 units between any lower value and any higher value. As an example, if it is stated that the amount of a component or a value of a process variable such as, for example, temperature, pressure, time and the like is, for example, from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to 51 , 30 to 32 etc. are expressly enumerated in this specification. For values which are less than one, one unit is considered to be 0.0001 , 0.001 , 0.01 or 0.1 as appropriate. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner. As can be seen, the teaching of amounts expressed as "parts by weight" herein also contemplates the same ranges expressed in terms of percent by weight. Thus, an expression in the Detailed Description of the Invention of a range in terms of at "V parts by weight of the resulting polymeric blend composition" also contemplates a teaching of ranges of same recited amount of "x" in percent by weight of the resulting polymeric blend composition."

[0042] Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints. The use of "about" or "approximately" in connection with a range applies to both ends of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", inclusive of at least the specified endpoints.

[0043] The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. The term "consisting essentially of" to describe a combination shall include the elements, ingredients, components or steps identified, and such other elements ingredients, components or steps that do not materially affect the basic and novel characteristics of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, ingredients, components or steps herein also contemplates embodiments that consist essentially of the elements, ingredients, components or steps. By use of the term "may" herein, it is intended that any described attributes that "may" be included are optional.

[0044] Plural elements, ingredients, components or steps can be provided by a single integrated element, ingredient, component or step. Alternatively, a single integrated element, ingredient, component or step might be divided into separate plural elements, ingredients, components or steps. The disclosure of "a" or "one" to describe an element, ingredient, component or step is not intended to foreclose additional elements, ingredients, components or steps. All references herein to elements or metals belonging to a certain Group refer to the Periodic Table of the Elements published and copyrighted by CRC Press, Inc. , 1989. Any reference to the Group or Groups shall be to the Group or Groups as reflected in this Periodic Table of the Elements using the lUPAC system for numbering groups.

[0045] It will be appreciated that concentrates or dilutions of the amounts recited herein may be employed. In general, the relative proportions of the ingredients recited will remain the same. Thus, by way of example, if the teachings call for 30 parts by weight of a Component A, and 10 parts by weight of a Component B, the skilled artisan will recognize that such teachings also constitute a teaching of the use of Component A and Component B in a relative ratio of 3: 1 . Teachings of concentrations in the examples may be varied within about 25% (or higher) of the stated values and similar results are expected. Moreover, such compositions of the examples may be employed successfully in the present methods.

[0046] It is understood that the above description is intended to be illustrative and not restrictive. Many embodiments as well as many applications besides the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the invention should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. The omission in the following claims of any aspect of subject matter that is disclosed herein is not a disclaimer of such subject matter, nor should it be regarded that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter.

Claims

Claim 1 : A structural tape comprising:

an adhesive material including:

a solid rubber;

a liquid rubber; and

an epoxy;

wherein the tape is weldable and the adhesive is substantially free of any fibrous filler and includes less than about 20% of any conductive filler.

Claim 2: The structural tape of claim 1 , wherein the liquid rubber is present in the adhesive in an amount of at least about 1 %, at least about 2%, at least about 3% or even at least about 4%.

Claim 3: The structural tape of claim 1 or claim 2, wherein the liquid rubber is present in the adhesive in an amount of less than about 10%, less than about 7%, or even less than about 5%.

Claim 4: The structural tape of any of the preceding claims, wherein the epoxy is a solid epoxy, a semi-solid epoxy, a liquid epoxy, or any combination thereof.

Claim 5: The structural tape of any of the preceding claims, wherein the epoxy includes at least about 5%, at least about 10%, at least about 20% or even at least about 25% of a liquid epoxy resin.

Claim 6: The structural tape of any of the preceding claims, wherein the epoxy includes at least about 5%, at least about 10%, or even at least about 20% of a solid epoxy resin.

Claim 7: The structural tape of any of the preceding claims, wherein the epoxy includes at least about 1 %, at least about 3%, or even at least about 5% of a semi-solid epoxy resin. Claim 8: The structural tape of any of the preceding claims, wherein the adhesive includes less than 15% of any conductive filler.

Claim 9: The structural tape of any of the preceding claims, wherein the adhesive includes a non-conductive filler.

Claim 10: The structural tape of any of the preceding claims, wherein the adhesive includes at least about 4%, at least about 6%, at least about 8%, or even at least about 10% of a non-conductive filler.

Claim 1 1 : The structural tape of any of the preceding claims, wherein a 2mm thickness of tape exposed to oven bake temperatures of at least about 165°C has a resulting sag of less than 1 mm, less than 0.8 mm, or even less than 0.5 mm.

Claim 12: The structural tape of any of the preceding claims, wherein the tape is substantially free of any core shell component.

Claim 13: The structural tape of any of the preceding claims, wherein the adhesive has a viscosity of at least 8 Nm with Torque Rheomoter test (XSS-300) under a condition of 40 rpm at 60C.

Claim 14: The structural tape of any of the preceding claims, wherein the adhesive has a viscosity of less than about 28 Nm with Torque Rheometer test (XSS-300) under a condition of 40 rpm at 60C.

Claim 15: The structural tape of any of the preceding claims, wherein the tape is tacky at room temperature.

Claim 16: The structural tape of any of the preceding claims, wherein the ratio of liquid rubber to solid rubber is from about 2: 1 to about 1 :2. Claim 17: The structural tape of any of the preceding claims, wherein the ratio of liquid rubber to solid rubber is about 1 : 1 .

Claim 18: The structural tape of any of the preceding claims, wherein the ratio of liquid rubber to solid rubber is about 4:5.

Claim 19: The structural tape of any of the preceding claims, including a tackifier in the adhesive in an amount of from about 0.2% to about 10% of the adhesive.

Claim 20: The structural tape of any of the preceding claims, wherein the tack of the adhesive including a tackifier increases by at least 1000% percent as compared to the adhesive without the tackifier.

Claim 21 : The structural tape of any of the preceding claims, wherein the tack of the adhesive including a tackifier increases by at least 3000% percent as compared to the adhesive without the tackifier.