Two-part epoxy adhesive that co-cures with urethane adhesives

Abstract

Two-part adhesive compositions include Part A) a curative part including at least one diamine curing agent and at least one modified aralkylene diamine curing agent, and Part B) an epoxy part including at least one epoxy resin. The two-part adhesive composition, upon mixing cures at room temperature, and the curing of the two-part adhesive composition occurs even if the mixed two-part adhesive composition is placed adjacent to an uncured or partially cured two-part curing urethane adhesive.

Description

[0001] TWO-PART EPOXY ADHESIVE THAT CO-CURES WITH URETHANE ADHESIVES

[0002] Summary

[0003] Disclosed herein are two-part epoxy adhesive compositions that when the uncured epoxy adhesive is placed near an uncured or partially cured urethane adhesive, the epoxy adhesive fully cures. Also disclosed are articles that contain the two-part epoxy adhesive compositions, and methods of forming articles that contain the two-part epoxy adhesive composition.

[0004] In some embodiments, the two-part adhesive composition comprises Part A) a curative part comprising at least one diamine curing agent and at least one modified aralkylene diamine curing agent, and Part B) an epoxy part comprising at least one epoxy resin. The two-part adhesive composition, upon mixing cures at room temperature, and the curing of the two-part adhesive composition occurs even if the mixed two-part adhesive composition is placed adjacent to an uncured or partially cured two-part curing urethane adhesive.

[0005] Also disclosed are articles. In some embodiments, the article comprises a first substrate with a first major surface and a second major surface, a first curable adhesive composition, comprising a room temperature curing two-part adhesive composition formed by mixing a two-part adhesive composition, and a second curable adhesive composition comprising a two-part room temperature curing two-part adhesive composition formed by mixing a two-part adhesive composition. The second curable adhesive composition is disposed adjacent to or atop the first curable adhesive composition. If the first curable adhesive composition comprises the two-part epoxy adhesive composition described above, the second adhesive composition comprises a two- part urethane adhesive composition, and if the first curable adhesive composition comprises a two-part urethane adhesive composition the second adhesive composition comprises the two-part epoxy adhesive composition described above.

[0006] Also disclosed are methods of forming articles. In some embodiments, the method of forming an article comprises providing a substrate with a first major surface and a second major surface, providing a first curable adhesive comprising a room temperature curing epoxy adhesive composition, mixing the two parts of the first curable adhesive to form a first mixed composition and disposing the first mixed composition on at least a portion of the first major surface of the substrate, providing a second curable adhesive comprising a room temperature curing urethane adhesive composition, mixing the two parts of the second curable adhesive to form a second mixed composition and disposing the second mixed composition on at least a portion of the first major surface of the substrate adjacent to the disposed first mixed composition or atop the first mixed composition and permitting the curable adhesives to cure at room temperature.

[0007] Brief Description of the Drawings

[0008] The present application may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings.

[0009] Figure 1 is a cross-sectional view of an article of this disclosure.

[0010] Figure 2 is a cross-sectional view of another article of this disclosure.

[0011] Figure 3 is a cross-sectional view of yet another article of this disclosure.

[0012] Detailed Description

[0013] A number of applications utilize a polyurethane adhesive layer adjacent to another structural adhesive. In many embodiments, the polyurethane layer and the structural adhesive are both two-part room temperature curing compositions that are dispensed adjacent to each other. In many embodiments, the structural adhesive is an epoxy adhesive. Often the room temperature curing two-part epoxy adhesives contain amino curing agents, amino curing catalysts or both. Since the isocyanates present in the two- part urethane compositions are reactive with amino compounds, the amino compounds from the epoxy adhesive can migrate into the urethane composition and react with the isocyanate compounds. Typically, isocyanates are more reactive with amines than with the polyols present in the two-part urethane adhesive. Because if the amine curative from the two-part epoxy adhesive migrates into the two-part urethane adhesive and reacts with the isocyanate present, it forms a urea and thus is not available to cure the epoxy adhesive. This can deplete the amount of amino curing agent in the epoxy adhesive, causing incomplete cure of the epoxy adhesive, Additionally, the reaction of epoxy adhesive amine curing agent with the isocyanate of the urethane adhesive, depletes the content of isocyanate and also gives incomplete curing in the urethane adhesive. The incomplete curing can be particularly pronounced at the region where the epoxy adhesive and the urethane composition are in contact. This can create a weak boundary layer between the epoxy adhesive and the urethane composition. In some instances, the epoxy structural adhesive and / or the urethane adhesive can be so incompletely cured in the interface region such that the surface of one or both of the adhesives remains tacky.

[0014] In this disclosure, two-part epoxy adhesives are described in which the curative portion of the two-part adhesive contain an epoxy curative made from formaldehyde oligomer with 1,3-benzenedimethanamine and phenol such that epoxy adhesive fully cures and the epoxy adhesive and urethane adhesives have limited interaction when disposed adjacent to each other. Additionally, other components in the epoxy adhesive, such as glass bubbles, aid in reducing the migration of the epoxy curative compounds into the urethane composition by reducing the area of contact between the epoxy adhesive and the urethane composition.

[0015] The term “adhesive” as used herein refers to polymeric compositions useful to adhere together two adherends. Examples of adhesives are structural adhesives.

[0016] Structural adhesives refer to adhesives that that can bond other high strength materials (e.g., wood, composites, or metal) so that the adhesive bond strength is in excess of 6.0 MPa (1000 psi).

[0017] The terms “epoxy-based” and “urethane-based” describe adhesive compositions that contain curable epoxy compositions and curable isocyanate compositions (isocyanates and polyols).

[0018] The terms "room temperature" and "ambient temperature" are used interchangeably to mean temperatures in the range of 20°C to 25°C.

[0019] The terms “polymer” and “macromolecule” are used herein consistent with their common usage in chemistry. Polymers and macromolecules are composed of many repeated subunits. As used herein, the term “macromolecule” is used to describe a group attached to a monomer that has multiple repeating units. The term “polymer” is used to describe the resultant material formed from a polymerization reaction. The term “adjacent” as used herein refers to two layers that are directly next to each other and in contact with each other. The term “atop” as used herein refers to a layer that is on top of another layer and in direct contact with the other layer.

[0020] The term “alkyl” refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. The alkyl can be linear, branched, cyclic, or combinations thereof and typically has 1 to 20 carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

[0021] The term “aryl” refers to a monovalent group that is aromatic and carbocyclic. The aryl can have one to five rings that are connected to or fused to the aromatic ring. The other ring structures can be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.

[0022] The term “alkylene” refers to a divalent group that is a radical of an alkane. The alkylene can be straight-chained, branched, cyclic, or combinations thereof. The alkylene often has 1 to 20 carbon atoms. In some embodiments, the alkylene contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of the alkylene can be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms.

[0023] The term “arylene” refers to a divalent group that is carbocyclic and aromatic. The group has one to five rings that are connected, fused, or combinations thereof. The other rings can be aromatic, non-aromatic, or combinations thereof. In some embodiments, the arylene group has up to 5 rings, up to 4 rings, up to 3 rings, up to 2 rings, or one aromatic ring. For example, the arylene group can be phenylene.

[0024] The term “aralkylene” refers to a divalent group of formula -R / '-Ar3- where Rais an alkylene and Ar3is an arylene (i.e., an alkylene is bonded to an arylene).

[0025] The term “alkoxy” refers to a monovalent group of formula -ORawhere Rais an alkyl group. The term “aryloxy” refers to a monovalent group of formula -ORawhere Rais an aryl group.

[0026] Disclosed herein are two-part adhesive compositions that are room temperature curing. Room temperature curable two-part adhesives are ones in which the two parts are kept separate until the two parts are mixed to initiate curing. The two-part adhesives cure even when adjacent to curing urethane adhesives.

[0027] As was mentioned above, two-part curable epoxy-based adhesives when placed adjacent to curable urethane adhesives tend to give incomplete curing. This is because the curatives from the two-part epoxy-based adhesive can be absorbed into the urethane adhesive leaving a paucity of curative in the epoxy-based adhesive, and at the same time reduce the available reactive species (isocyanates) in the curable urethane adhesive. Thie effect is particularly apparent at the interface between the epoxy-based adhesive and urethane-based adhesive can remain tacky, evidencing incomplete cure of the epoxy adhesive, the urethane adhesive, or both. The curable two-part adhesive compositions of this disclosure overcome this difficulty.

[0028] In some embodiments, the two-part adhesive composition comprises Part A) a curative part comprising at least one diamine curing agent and at least one modified aralkylene diamine curing agent, and Part B) an epoxy part comprising at least one epoxy resin. The two-part adhesive composition may include a variety of additives, where the additives may be present in Part A, Part B, or both. The two-part adhesive composition, upon mixing cures at room temperature, and the curing of the two-part adhesive composition occurs even if the mixed two-part adhesive composition is placed adjacent to an uncured two-part curing urethane composition.

[0029] The two-part adhesive composition includes Part A, the curative part. Part A includes at least one diamine curing agent and at least one modified aralkylene diamine curing agent and may include a variety of additives. In this way, Part A can be described as a mixture of the curative or curative combination and the additive or additive combination. The term “curing agent” as used herein is used according to the common usage in the epoxy curing art, namely it encompasses compounds (such as amino groups) that react with epoxy rings, and curing catalysts, compounds that catalyze the homopolymerization of epoxy rings.

[0030] The curative or curative combination comprises at least one diamine curing agent and at least one modified aralkylene diamine curing agent. A wide variety of diamine curing agents are suitable. In some embodiments, the at least one diamine curing agent comprises a compound of general Formula 1 :

[0031] H2N-[(CH2)a-O-]n(CH2)b-NH2 Formula 1 where a is an integer of 1 or greater, b is an integer of 1 or greater and may be the same as a or may be different, n is an integer of 2 or greater.

[0032] In some embodiments, the at least one diamine curing agent comprises a compound of general Formula 1 where a is 2, b is 2, and n is 3. An example of such a curing agent is 4,7, 10-tri oxa- 1,13 -tridecanediamine.

[0033] The diamine curing agent typically comprises 20-50 weight% based upon the total weight of Part A.

[0034] The curative or curative combination also comprises at least one modified aralkylene diamine curing agent. In some embodiments, the modified aralkylene diamine curing agent comprises an oligomer of 1,3-benzeneeimethanamine, formaldehyde, and phenol. An example of a suitable modified aralkylene diamine curing agent is ANCAMINE 2422 from Evonik Industries, AG

[0035] The modified aralkylene diamine curing agent typically comprises 15-35 weight% based upon the total weight of Part A.

[0036] In some embodiments, the curative or curative combination comprises one or more additional curing agents. These curing agents may be compounds that react with epoxy rings, curing catalysts, or combinations thereof.

[0037] In some embodiments, the curative or curative combination further comprises one or more curing catalysts. Examples of curing catalysts include tertiary amines and metal salts. Examples of particularly suitable curing catalysts include calcium nitrate tetrahydrate, and the tertiary amine curing agent VERSAMINE EH 50 from BASF Corporation.

[0038] Besides the curative or curative combination, Part A may also comprise one or more additives. Among the additives are glass bubbles, at least one hydroxide salt selected from magnesium hydroxide, aluminum hydroxide or a combination thereof, at least one intumescent polyphosphate reagent, at least one pigment, at least one flame retardant, at least one coupling agent, and fumed silica.

[0039] In some embodiments, Part A optionally comprises glass bubbles or polymeric bubbles. Glass bubbles and polymeric bubbles are particularly suitable because it has been found that the presence of glass bubbles decreases the density of the cured adhesive. It is also believed the presence of glass or polymeric bubbles in the adhesive assists in hindering the flow of amine curative into the curable urethane adhesive. Additionally, the presence of glass or polymeric bubbles in the curable urethane adhesive can also assist in hindering the flow of amine curative across the interface. In some embodiments, the glass bubbles comprise hollow borosilicate glass bubbles with a true density of from 0.1-0.8 g / cm3. Examples of suitable glass bubbles include XLD3000 glass bubbles from 3M Company, St. Paul, MN. In some embodiments, the glass bubbles have been surface modified with an amino silane surface treatment agent. Amino-silane surface treatment agents, also know as amino-silane coupling agents, are well known materials in the adhesive arts. Typically, the amino-silane surface treatment agents are of general Formula 2:

[0040] A-RJ-B

[0041] Formula 2 wherein A comprises an amino group, -NR5R6where R5and R6are each independently an H atom or an alkyl group, wherein at least one of R5and R6is an H atom; R1is a linking group comprising an alkylene group with 1-5 carbon atoms; and B is a group -SiR2R3R4wherein R2and R3are alkoxy groups with 1-4 carbon atoms, and R4is an alkyl, alkoxy or aryloxy group.

[0042] These agents function to treat the surface of the glass bubbles in that the silane group reacts with the surface of the glass bubble, and the amino group is available to react with epoxy resins of Part B. In this way the glass bubbles can become incorporated into the cured epoxy matrix.

[0043] The amount of glass bubbles in Part A, if present, are 5-40 weight% based upon the total weight of Part A.

[0044] In some embodiments, Part A further optionally comprises at least one hydroxide salt selected from magnesium hydroxide, aluminum hydroxide or a combination thereof. Examples of suitable hydroxide salts include the high purity magnesium hydroxide MAGNIFIN H-7 from J.M. Huber Corporation, and aluminum hydroxide trihydrates ATH 916 and ATH 9400SG from J.M. Huber Corporation. The amount of hydroxide salt in Part A, if present, is 5-20 weight% based on the total weight of Part A. In some embodiments, Part A optionally comprises at least one intumescent polyphosphate reagent. In some embodiments, the at least one intumescent polyphosphate reagent comprises: ammonium polyphosphate; melamine polyphosphate; ethylene diamine phosphate, and combinations thereof. Examples of suitable intumescent polyphosphate reagent include INTUMAX AC-3 from Broadview Technologies, Newark, NJ. The amount of intumescent polyphosphate reagent in Part A, if present, is 5-40 weight% based upon the total weight of Part A.

[0045] In some embodiments, Part A optionally comprises at least one pigment. Examples of suitable pigments include carbon black such as VULCAN XC-72R from Cabot Corporation, and titanium dioxide such as TI-PURE R-960 from the Chemours Company, Wilmington, DE. The amount of pigment in Part A, if present, is 0.1-5 weight% based upon the total weight of Part A.

[0046] Part A may also comprise other flame-retardant agents in addition to or instead of the intumescent polyphosphate reagent. In some embodiments, the flame -retardant agent comprises boron-based flame retardants, melamine, aluminosilicate, red phosphorous powder, organophosphorus compounds, expendable graphite, talc, and combinations thereof. Particularly suitable additional flame-retardant agents include the ammonium polyphosphate available as EXOLIT AP 462 from Clariant. The one or more other flameretardant agents in Part A, if present, are 5-40 weight% based upon the total weight of Part A.

[0047] In some embodiments, Part A optionally comprises at least one coupling agent. In some embodiments, the coupling agents are amino-silane coupling agents. Such coupling agents are well known materials in the adhesive arts. Typically, the amino-silane coupling agents are of general Formula 2A:

[0048] A-R4-B

[0049] Formula 2A where A comprises an amino group, -NR5R6where R5and R6are each independently an H atom or an alkyl group, where at least one of R5and R6is an H atom, R1is a linking group comprising an alkylene group with 1-5 carbon atoms, and B is a group -SiR2R3R4wherein R2and R3are alkoxy groups with 1-4 carbon atoms, and R4is an alkyl, alkoxy or aryloxy group. The coupling agent is particularly suitable when glass bubbles are used, since the silane end of the coupling agent can bond to the surface of the glass bubbles and the amino group can react into the epoxy matrix to help to hold the glass bubbles in the epoxy matrix. Additional suitable coupling agents include the silsesquioxane oligomer available as WSA-9911 from Gelest Inc., Martinsville, PA. The one or more coupling agents in Part A, if present, are 0. 1-2.0 weight% based upon the total weight of Part A.

[0050] In some embodiments, Part A optionally comprises at least one fumed silica. Examples of suitable fumed silicas include the CAB-O-SIL materials TS 382 or TS 720 from Cabot Corporation. The one or more fumed silicas in Part A, if present, are 1.0-10.0 weight% based upon the total weight of Part A.

[0051] The two-part adhesive composition includes Part B, the epoxy part. Part B includes at least one epoxy resin and may include a variety of additives. In this way, Part B can be described as a mixture of the epoxy resin or epoxy resin mixture and the additive or additive combination.

[0052] Part B includes at least one epoxy resin. In some embodiments, the at least one epoxy resin comprises: a liquid diglycidyl ether of bisphenol F; a liquid diglycidyl ether of bisphenol A; a liquid epoxy novolac resin, a liquid aliphatic epoxy resin, a liquid cycloaliphatic epoxy resin; 1,4-cyclohexandimethanoldiglycidylether; 3,4- epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate; tetraglycidylmethylenedianiline; N,N,N',N'-tetraglycidyl-4,4'-methylenebisbenzenamine; triglycidyls of para-aminophenol, N,N,N',N'-tetraglycidyl-m-xylenediamine; and combinations thereof. Particularly suitable epoxy resins include the DGEBA (di-glycidyl ether of bisphenol A) resin EPON 828 and the aliphatic triglycidyl ether HELOXY 48 from Hexion Specialty Chemicals, Louisville, KY. In some embodiments, the at least one epoxy resin comprises 30-80% by weight of Part B.

[0053] Besides the epoxy resin or epoxy resin mixture, Part B may also comprise one or more additives. Among the additives are glass bubbles, at least one hydroxide salt selected from magnesium hydroxide, aluminum hydroxide or a combination thereof, at least one intumescent polyphosphate reagent, at least one pigment, at least one flame retardant, and fumed silica. Each of these additives is described above, and the amounts of the additives can similarly be used in Part B. Part B may also comprise at least one coupling agent. If used in Part B, the coupling agent is not an amino-silane coupling agent but rather an epoxy-silane coupling agent. Typically, the epoxy-silane coupling agents are of general Formula 2B:

[0054] A-RJ-B

[0055] Formula 2B where A comprises an epoxy group, R1is a linking group comprising an alkylene group with 1-5 carbon atoms, and B is a group -SiR2R3R4wherein R2and R3are alkoxy groups with 1-4 carbon atoms, and R4is an alkyl, alkoxy or aryloxy group. The coupling agent is particularly suitable when glass bubbles are used, since the silane end of the coupling agent can bond to the surface of the glass bubbles and the epoxy group can react into the epoxy matrix to help to hold the glass bubbles in the epoxy matrix. Additional suitable coupling agents include the silsesquioxane oligomer available as WSA-9911 from Gelest Inc., Martinsville, PA. The one or more coupling agents in Part B, if present, are 0.1-2.0 weight% based upon the total weight of Part B.

[0056] In some embodiments, the two-part adhesive composition comprises a Part A that comprises at least one diamine curing agent, at least one modified aralkylene diamine curing agent, at least one fumed silica, at least one flame retardant, magnesium hydroxide, an intumescent polyphosphate, an epoxy curing catalyst, and a tertiary amine epoxy curing agent. In some embodiments, the two-part adhesive composition comprises a Part B that comprises a first epoxy resin, a second epoxy resin, at least one coupling agent, at least one fumed silica, magnesium hydroxide, an intumescent polyphosphate, and at least one pigment.

[0057] Regardless of which part the additives are in, the overall amounts of the additives can vary. In some embodiments, the additives include glass or polymeric bubbles. Suitable glass bubbles are described above. The bubbles if present are present in an amount of from 1-40% by weight based on the total weight of the adhesive composition.

[0058] In some embodiments, the additives include hydroxide salts. Suitable hydroxide salts are described above. The hydroxide salts, if present are present in an amount of from 5-20% by weight based on the total weight of the adhesive composition. In some embodiments, the additives include intumescent polyphosphate reagents. The intumescent polyphosphate reagents, if present are present in an amount of from 5- 40% by weight based on the total weight of the adhesive composition.

[0059] In some embodiments, the additives include pigments. The pigments, if present are present in an amount of from 0.1-5 weight% based upon the total weight of the adhesive composition.

[0060] In some embodiments, the additives include flame-retardant agents in addition to or instead of the intumescent polyphosphate reagent. The flame-retardant agents, if present are present in an amount of from 5-40% by weight based on the total weight of the adhesive composition.

[0061] In some embodiments, the additive includes at least one coupling agent. The coupling agents may be of Formula 2A or 2B, depending upon which Part the coupling agent is disposed. The one or more coupling agents, if present, are 0.1-2.0 weight% based upon the total weight of the adhesive composition.

[0062] In some embodiments, the additive includes fumed silica. The fumed silicas, if present, are present in an amount of from 1.0-10.0 weight% based upon the total weight of the adhesive composition.

[0063] Besides the above listed additives, the adhesive composition may include other optional additives. In some embodiments, the adhesive composition further comprises in Part A, Part B, or both, an additive comprising water, thixotropic agents, catalysts, pigments, fdlers, coupling agents, and polymer bubbles, with the proviso that Part B does not include water.

[0064] The two-part adhesive compositions of this disclosure, have a wide range of desirable properties. As mentioned above, the curing of the two-part adhesive composition occurs even if the mixed two-part adhesive composition is placed adjacent to an uncured two-part curing urethane adhesive.

[0065] Two-part curing urethane adhesives are well known in the adhesive art. The two- part curing urethane adhesives include at least one polyisocyanate, at least one polyol, and may contain a wide range of other additives. Typically, the adhesive includes a curing catalyst to facilitate the reaction between the polyisocyanate and polyol. In many instances the curing catalyst is a metal compound such as di-butyl tin or a tertiary amine. As mentioned above, the reaction of a polyisocyanate with an amine to form a urea is much quicker than the reaction between a polyisocyanate and a polyol. Therefore, when the amine -containing two-part curing epoxy adhesive of this disclosure are disposed adjacent to the two-part curing urethane adhesive, the amine materials from the epoxy adhesive can transfer to the urethane adhesive and react with the polyisocyanates present therein. As discussed above, this transfer can adversely affect both curing adhesives, but can be particularly detrimental to the curing epoxy adhesive since the loss of amine curative can leave the epoxy adhesive not fully cured.

[0066] Examples of suitable two-part curing urethane adhesives include compositions such as 3M SCOTCH-WELD URETHANE ADHESIVE EC-3549. Other suitable urethanes include, for example 3M SCOTCH-WELD URETHANE ADHESIVE EC-3532, 3M SCOTCH-WELD URETHANE ADHESIVE EC-3535, and 3M SCOTCH-WELD URETHANE ADHESIVE DP604NS.

[0067] In some embodiments, the cured two-part adhesive compositions have additional desirable properties. Among the desirable properties is flame resistance. In some embodiments, the flame resistance is such that it meets the flame retardant UL94V0 test.

[0068] Also disclosed are articles. In some embodiments, the articles comprise a first substrate with a first major surface and a second major surface, a first curable adhesive composition, comprising a room temperature curing epoxy adhesive composition formed by mixing a two-part adhesive composition, and a second curable adhesive composition comprising a two-part room temperature curing urethane adhesive composition formed by mixing a two-part adhesive composition, wherein the first curable adhesive composition is disposed adjacent to the second curable adhesive composition and both the first curable adhesive composition and the second curable adhesive composition cure at room temperature. The first curable adhesive may be disposed next to each other or may be disposed atop each other.

[0069] The articles may further comprise a second substrate, such that upon curing the articles have a first substrate, a cured adhesive layer formed from two curing adhesives, and a second substrate.

[0070] A wide range of substrates are suitable for use in the articles of this disclosure. In some embodiments, the first and second substrates comprise a film, a rigid polymeric plate, or the surface of an article, wherein the article comprises a battery. In some embodiments, at least one of the first substrate and the second substrate comprises a battery or a battery component. In some embodiments, the battery component comprises a battery pack component or a battery cell. In some embodiments, the two-part adhesive bonds a battery pack lid to a cooling plate.

[0071] Suitable first curable adhesive compositions are described above and include two- part curable compositions comprising Part A) a curative part comprising at least one diamine curing agent and at least one modified aralkylene diamine curing agent; and Part B) an epoxy part comprising at least one epoxy resin. The two-part curable adhesive may also contain a variety of optional additives.

[0072] As described above, the curative part comprises a modified aralkylene diamine curing agent comprising a blend of 1,3-benzeneeimethanamine, a formaldehyde oligomer, and phenol, and the at least one diamine curing agent comprises a compound of general Formula 1:

[0073] H2N-[(CH2)a-O-]n(CH2)b-NH2

[0074] Formula 1 where a is an integer of 1 or greater, b is an integer of 1 or greater and may be the same as a or may be different, n is an integer of 2 or greater.

[0075] The second curable adhesive is a curable urethane adhesive comprising at least one polyol, at least one polyisocyanate, and at least one curing catalyst.

[0076] Also disclosed herein are methods of forming articles. In some embodiments, the method comprises providing a first substrate with a first major surface and a second major surface, providing a first curable adhesive comprising a room temperature curing two-part adhesive composition, mixing the two parts of the first curable adhesive to form a first mixed composition and disposing the first mixed composition on at least a portion of the first major surface of the substrate, providing a second curable adhesive comprising a different room temperature curing two-part adhesive composition, mixing the two parts of the second curable adhesive to form a second mixed composition and disposing the second mixed composition on at least a portion of the first major surface of the substrate adjacent to the disposed first mixed composition, or atop the first curable adhesive, and permitting the first curable adhesive and the second curable adhesive to cure at room temperature.

[0077] One of the first and second curable adhesives is an epoxy adhesive, and the other is a urethane adhesive. In some embodiments, the first curable adhesive comprises a room temperature curing two-part epoxy adhesive as described above. In other embodiments, the first curable adhesive comprises a comprises a room temperature curing two-part urethane adhesive.

[0078] The epoxy curable adhesive composition comprises Part A) a curative part comprising at least one diamine curing agent and at least one modified aralkylene diamine curing agent, and Part B) an epoxy part comprising at least one epoxy resin. The two-part epoxy may also contain a variety of additives. These two-part curable adhesives are described in detail above.

[0079] The urethane curable adhesive composition comprises at least one polyol, at least one polyisocyanate, and at least one curing catalyst, and wherein each of the first and second curable adhesive composition cures at room temperature and wherein each of the first and second curable adhesive composition may comprise additional optional additives.

[0080] The two-part adhesive can be mixed and disposed on a surface in a variety of ways. In some embodiments, one or both of the curable two-part adhesives can be mixed and then disposed on a surface. In other embodiments, one or both of the curable two-part adhesives can be simultaneously mixed and disposed through the use of a mixing and dispensing tool.

[0081] The disclosure may be further understood by reference to the figures. Figure 1 shows a cross-sectional view of an article of this disclosure. The article has first substrate 100, second substrate 400 with curable epoxy composition layer 200, curable urethane composition layer 300. Upon curing layers 200 and 300 form cured epoxy and urethane layers. Interface 250 fully cures such that the interface is not a weak boundary layer. In this embodiment, the two curable layers are atop each other.

[0082] Figure 2 shows a cross-sectional view of another article of this disclosure. The article has first substrate 100, second substrate 400 with curable epoxy composition layer 200, curable urethane composition layer 300. Upon curing layers 200 and 300 form cured epoxy and urethane layers. Interface 250 fully cures such that the interface is not a weak boundary layer. In this embodiment, the two curable layers are beside each other.

[0083] Figure 3 shows a cross-sectional view of another article of this disclosure. In this article, substrate 400 has layers of curable epoxy composition layer 200, curable urethane composition layer 300. Upon curing layers 200 and 300 form cured epoxy and urethane layers. Interface 250 fully cures such that the interface is not a weak boundary layer. In this embodiment, the two curable layers are atop each other and upon curing form a coating and do not adhere together substrates.

[0084] Examples These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, unless noted otherwise. Solvents and other reagents used were obtained from Sigma-Aldrich Chemical Company; Milwaukee, Wisconsin unless otherwise noted. The following abbreviations are used: RPM = revolutions per minute. The terms “weight %”, “% by weight”, and “wt%” are used interchangeably.

[0085] Table 1: Materials

[0086] Test Methods

[0087] Co-Curing Test

[0088] The ability for a 2-part epoxy adhesive to cure when placed adjacent to a 2-part urethane adhesive was tested. A layer of PU was dispensed according to the manufacturer’s instructions onto the surface of a PTFE (polytetrafluoroethylene) release liner. Immediately a layer of the epoxy adhesive was disposed adjacent to the layer of PU adhesive. Comparative adhesives were dispensed according to the manufacturer’s instructions, experimental adhesives were mixed as 2 to 1 weight ratio. After allowing the adhesives to cure for 24 hours at ambient temperature (that is to say room temperature, about 22°C), the adhesives were peeled apart at the interface area. The results are summarized in Table 3 below.

[0089] Examples EX-1 - EX2 and Comparative Examples CEX-1 - CEX3

[0090] Two-part epoxy adhesive compositions were prepared according to the General Assembly method using the components shown in Table 2, and tested according to the above test method. For Comparative Examples CEX2 and CEX3, the commercially available 2-part epoxy adhesives EA-1 and EA-2 were used.

[0091] General Assembly of two-part Adhesives

[0092] Part B Assembly

[0093] Quantities of DGEBA, ATE, CA-2 were mixed in a high-speed mixer at 2,200 RPM at ambient temperature (i.e., 21°C) for 1 - 2 minutes. After mixing, FS-1 or FS-2 was added, and speed mixed at 2,200 RPM for 2 - 4 minutes. The remaining ingredients were added, and speed mixed at 2,200 RPM for 1 - 2 minutes.

[0094] Part A Assembly Quantities of TTD and Cure Agent or MXDA were added to a plastic cup and mixed well. Then Ca(NO3)2-4H2O was added, by means of a high-speed mixer operating at 2,200 RPM at ambient temperature (i.e., 21°C) for 5-10 minutes. After the Ca(NO3)2-4H2O was dissolved, CA-1 and Catalyst were added and mixed. FS-1 or FS-2 was added, and speed mixed at 2,200 RPM for 2 - 4 minutes. The remaining ingredients were added, and the mixture was speed mixed at 2,200 RPM for 1 - 2 minutes.

[0095] Table 2: Compositions (in weight percent) Testing

[0096] The adhesive compositions were tested according to the Co-Curing Test Method described above. The Results are presented in Table 3 below.

[0097] Table 3

[0098] In Table 3, the two Examples have a failure mode away from the interface meaning that the two adhesives were able to co-cure effectively and form a strong interfacial bond. In the Comparative Examples where the failure mode was at the interface and the epoxy surface felt tacky, this indicates that that the epoxy adhesive did not fully cure with the result that a weak interfacial bond was formed.

Claims

What is claimed is:

1. A two-part adhesive composition comprising:Part A) a curative part comprising at least one diamine curing agent and at least one modified aralkylene diamine curing agent;Part B) an epoxy part comprising at least one epoxy resin; wherein the two-part adhesive composition, upon mixing cures at room temperature, and wherein the curing of the two- part adhesive composition occurs even if the mixed two-part adhesive composition is placed adjacent to an uncured or partially cured two-part curing urethane adhesive.

2. The two-part adhesive composition of claim 1, wherein the at least one modified aralkylene diamine curing agent comprises: an oligomer of 1,3-benzeneeimethanamine, formaldehyde, and phenol.

3. The two-part adhesive composition of claim 1, wherein the at least one diamine curing agent comprises a compound of general Formula 1:H2N-[(CH2)a-O-]n(CH2)b-NH2Formula 1 wherein a is an integer of 1 or greater; b is an integer of 1 or greater and may be the same as a or may be different; n is an integer of 2 or greater.

4. The two-part adhesive composition of claim 1, wherein the at least one diamine curing agent comprises a compound of general Formula 1:H2N-[(CH2)a-O-]n(CH2)b-NH2Formula 1 wherein a is 2; b is 2; n is 3.

5. The two-part adhesive composition of claim 1, wherein the curative part further comprises.an epoxy curing catalyst; and a tertiary amine epoxy curing agent.

6. The two-part adhesive composition of claim 1, further comprising at least one additive, wherein one or more of the additive components are present in Part A, Part B, or both, the additive components comprise: glass bubbles: at least one hydroxide salt selected from magnesium hydroxide, aluminum hydroxide or a combination thereof; at least one intumescent polyphosphate reagent; at least one pigment; at least one flame retardant; at least one coupling agent; and fumed silica.

7. The two-part adhesive composition of claim 6, wherein Part A) comprises: at least one diamine curing agent; at least on modified aralkylene diamine curing agent; at least one fumed silica; at least one flame retardant; magnesium hydroxide; an intumescent polyphosphate; an epoxy curing catalyst; and a tertiary amine epoxy curing agent.

8. The two-part adhesive composition of claim 6, wherein Part B) comprises: a first epoxy resin; a second epoxy resin; at least one coupling agent; at least one fumed silica; magnesium hydroxide;an intumescent polyphosphate; and at least one pigment.

9. An article comprising: a first substrate with a first major surface and a second major surface; a first curable adhesive composition, comprising a room temperature curing two-part adhesive composition formed by mixing a two-part adhesive composition; and a second curable adhesive composition comprising a two-part room temperature curing two-part adhesive composition formed by mixing a two-part adhesive composition, wherein the second curable adhesive composition is disposed adjacent to or atop the first curable adhesive composition and wherein if the first curable adhesive composition comprises a two-part epoxy adhesive composition the second adhesive composition comprises a two-part urethane adhesive composition, and if the first curable adhesive composition comprises a two-part urethane adhesive composition the second adhesive composition comprise a two-part epoxy adhesive composition.

10. The article of claim 9, wherein the two-part curable adhesive composition comprises: Part A) a curative part comprising at least one diamine curing agent and at least one modified aralkylene diamine curing agent; andPart B) an epoxy part comprising at least one epoxy resin.

11. The article of claim 10, wherein the at least on modified aralkylene diamine curing agent comprises: an oligomer of 1,3-benzeneeimethanamine, formaldehyde, and phenol.

12. The article of claim 10, wherein the at least one diamine curing agent comprises a compound of general Formula 1:H2N-[(CH2)a-O-]n(CH2)b-NH2Formula 1 wherein a is an integer of 1 or greater; b is an integer of 1 or greater and may be the same as a or may be different; n is an integer of 2 or greater.

13. The article of claim 10, wherein the first curable adhesive further comprises at least one additive, wherein one or more of the additive components are present in Part A, Part B, or both, the additive components comprise: glass bubbles: at least one hydroxide salt selected from magnesium hydroxide, aluminum hydroxide or a combination thereof; at least one intumescent polyphosphate reagent; at least one pigment; at least one flame retardant; at least one coupling agent; and fumed silica.

14. The article of claim 9, wherein the second curable adhesive comprises: at least one polyol; at least one polyisocyanate; and at least one curing catalyst.

15. The article of claim 9, further comprising a second substrate, wherein the second substrate is in contact with the first curable adhesive, the second curable adhesive or both.

16. The article of claim 15, wherein the first curable adhesive and second curable adhesive are cured.

17. The article of claim 9, wherein the first and second substrates comprises a film, a rigid polymeric plate, or the surface of an article, wherein the article comprises a battery.

18. A method of forming an article comprising: providing a substrate with a first major surface and a second major surface; providing a first curable adhesive comprising a room temperature curing epoxy adhesive composition;mixing the two parts of the first curable adhesive to form a first mixed composition and disposing the first mixed composition on at least a portion of the first major surface of the substrate; providing a second curable adhesive comprising a room temperature curing urethane adhesive composition; mixing the two parts of the second curable adhesive to form a second mixed composition and disposing the second mixed composition on at least a portion of the first major surface of the substrate adjacent to the disposed first mixed composition or atop the first mixed composition; and permitting the curable adhesives to cure at room temperature.

19. The method of claim 18, wherein: the first curable adhesive composition comprises:Part A) a curative part comprising at least one diamine curing agent and at least one modified aralkylene diamine curing agent; andPart B) an epoxy part comprising at least one epoxy resin, and the second curable adhesive composition comprises: at least one polyol; at least one polyisocyanate; and at least one curing catalyst, and wherein each of the first and second curable adhesive composition cures at room temperature and wherein each of the first and second curable adhesive composition may comprise additional optional additives.

20. The method of claim 18, wherein: the first curable adhesive composition comprises: at least one polyol; at least one polyisocyanate; and at least one curing catalyst; and the second curable adhesive composition comprises:Part A) a curative part comprising at least one diamine curing agent and at least onemodified aralkylene diamine curing agent; andPart B) an epoxy part comprising at least one epoxy resin, and wherein each of the first and second curable adhesive composition cures at room temperature and wherein each of the first and second curable adhesive composition may comprise additional optional additives.

21. The method of claim 18, wherein mixing and disposing of the first curable adhesive comprises simultaneous mixing and disposing through the use of a mixing and dispensing tool.

22. The method of claim 18, wherein mixing and disposing of the second curable adhesive comprises simultaneous mixing and disposing through the use of a mixing and dispensing tool.

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