Impact-resistant epoxy adhesive with extended curing area

Abstract

The present invention relates to a one-component (1K) epoxy adhesive that can be fully cured under a wide range of curing conditions.

Description

[Technical Field]

[0001] This disclosure relates to impact-resistant epoxy adhesive compositions that can be cured under a wide range of time / temperature conditions, methods for producing cured adhesives, and products. [Background technology]

[0002] One-component (1K) epoxy adhesives contain a relatively inert, heat-activated latent curing agent (also called a curing agent) at room temperature, such as dicyandiamide (DICY). In addition to the curing agent, one-component adhesives may contain a latent catalyst or accelerator to catalyze / accelerate the curing of the adhesive upon heating. Known one-component storage-stable and "impact-resistant" structural adhesives have reaction initiation temperatures of 160°C or higher, and OEMs require good impact resistance properties (even at low temperatures such as -30°C or -40°C) after curing at 155°C for 10 minutes or 190°C for 60 minutes, respectively. To reduce energy consumption, there is a need to lower the reaction initiation temperature while maintaining the room-temperature storage stability of these one-component epoxy structural adhesives.

[0003] To date, one-component epoxy adhesive formulations using catalysts or accelerators for dicyandiamide (DICY) curing of epoxy resins have not yielded a desirable combination of storage stability, impact resistance of the cured epoxy, and a lower starting temperature. Existing one-component epoxy adhesives do not fully cure even after baking at 140°C for approximately 15 minutes and do not exhibit the “full-spectrum” impact properties described herein. As used herein, “full-spectrum” impact properties refer to the cured composition exhibiting sufficient adhesion and impact resistance over a test temperature range from 80°C to -30°C and even down to -40°C.

[0004] One-component reinforced epoxy adhesives containing a latent curing agent mixture include dihydrazide adipic acid (ADH). However, under low-temperature curing conditions, the adhesive properties and / or full-spectrum impact properties are inferior, requiring relatively high concentrations of ADH.

[0005] 2,4,6-Tris(dimethylaminomethyl)phenol is a catalyst and curing agent that cures epoxy at room temperature and is therefore unsuitable for 1K epoxy. U.S. Patent No. 9000120 discloses that this tertiary amine becomes latent when mixed with novolac resin, but exhibits poor storage stability. At high concentrations (over 3% by weight) of phenolic blocked tertiary amines, viscosity increases during storage, reducing adhesion to steel and aluminum substrates.

[0006] In some cases, the inclusion of imidazole has been disclosed. For example, U.S. Patent No. 9,546,243 teaches that a latent epoxy curing agent may contain imidazole and an amine such as 2,4,6-tris(dimethylaminomethyl)phenol that dissolves in polyphenol resins, including polymers or copolymers of phenols substituted with unsaturated ethylene groups, polymers and copolymers of phenol-substituted acrylates or methacrylates, or polymers of vinylphenol and propenylphenol. It has been suggested that the phenol resin may also contain copolymers of such unsaturated phenols with other polymerizable alkene-substituted compounds such as styrene, γ-methylstyrene, acrylic acid esters, methacrylic acid esters, and vinyl esters. However, imidazole is not advantageous for impact-resistant epoxy adhesives because it causes homopolymerization of the epoxy network, forming a brittle thermosetting resin upon curing.

[0007] Attempts have also been made to use high concentrations of modified urea in such compositions. However, modified urea has problems such as a short storage period due to increased viscosity during storage before distribution and curing, reduced adhesion to steel and aluminum surfaces, and / or reduced impact properties when cured under "over-scorching" conditions, such as 190°C for 60 minutes, especially when the bonded area after curing is tested at low temperatures.

[0008] Therefore, there is a need for a single-package (so-called "1K") epoxy adhesive composition with a low starting temperature that has storage stability at room temperature and exhibits "full-spectrum" curing impact resistance whether cured at 140°C for 15 minutes (low-temperature curing) or at 190°C for 60 minutes (high-temperature curing). This disclosure addresses at least some of these needs. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] U.S. Patent No. 9000120 [Patent Document 2] U.S. Patent No. 9546243 [Overview of the Initiative] [Means for solving the problem]

[0010] This disclosure relates to a novel composition of liquid epoxy structural adhesives that, upon curing, form a cured adhesive portion having stress resistance, preferably impact resistance, and is useful for bonding substrates such as metal substrates together. The disclosure also provides an adhesive assembly obtained by applying an uncured adhesive to one or both substrates to be bonded, bringing the substrates into contact so that the adhesive is positioned between them, and curing the adhesive, as well as a method for producing these liquid epoxy adhesives, a method for bonding substrates, and a product including the adhesive assembly. Throughout this disclosure, various embodiments of the present invention are described, including, for example, the following:

[0011] Embodiment 1 A structural adhesive composition useful for vehicle manufacturing, (i) Epoxy resins containing diglycidyl ethers of substituted or unsubstituted bisphenols; (ii) Latent reagents; (iii) Modified urea promoters; (iv) Dicyandiamide; (v) at least one reinforcing agent; (vi) at least one filler; and (vii) An epoxy resin that is arbitrarily different from (i). An adhesive composition comprising, consisting essentially of, or consisting of these.

[0012] Embodiment 2 The adhesive composition according to Embodiment 1, wherein the epoxy resin (i) has an epoxy equivalent weight (EEW) of about 150 to about 225.

[0013] Embodiment 3 The adhesive composition according to Embodiment 2, wherein the epoxy resin (i) has an EEW of about 170 to about 200.

[0014] Embodiment 4 The adhesive composition according to Embodiment 2, wherein the epoxy resin (i) has an EEW of about 185 to about 192.

[0015] Embodiment 5 The adhesive composition according to Embodiment 2, wherein the epoxy resin (i) has an EEW of about 172 to about 179.

[0016] Embodiment 6 The adhesive composition according to any one of the preceding embodiments, wherein the epoxy resin (i) contains a diglycidyl ether of a substituted or unsubstituted bisphenol, preferably diglycidyl ether of bisphenol A (DGEBA), diglycidyl ether of bisphenol F (DGEBF) or a combination thereof.

[0017] Embodiment 7 The adhesive composition according to any one of the preceding embodiments, comprising one epoxy resin.

[0018] Embodiment 8 The adhesive composition according to any one of Embodiments 1 to 6, comprising two epoxy resins.

[0019] Embodiment 9 The adhesive composition according to any one of Embodiments 1 to 6, comprising three epoxy resins.

[0020] Embodiment 10 An adhesive composition according to any one of Embodiments 1 to 6, comprising four or more epoxy resins.

[0021] Embodiment 11 An adhesive composition according to any one of the prior embodiments, comprising about 30 to about 60 by weight of the epoxy resin (i) based on the weight of the composition.

[0022] Embodiment 12 The adhesive composition according to any one of the prior embodiments, wherein the latent reagent is a thermally activated reagent containing a modified polymer tertiary amine having an activation temperature in the range of about 120°C to about 138°C.

[0023] Embodiment 13 The adhesive composition according to specific embodiment 12, wherein the latent reactant is a thermally activated reagent comprising a tertiary amine, a polyhydroxyphenylalkyl polymer resin, and an auxiliary organic agent.

[0024] Embodiment 14 The adhesive composition according to Embodiment 12 or 13, wherein the auxiliary organic agent comprises an oligomer or polymer containing an acrylic portion.

[0025] Embodiment 15 The adhesive composition according to Embodiment 12 or 13, wherein the tertiary amine comprises at least one hydroxyl substituent.

[0026] Embodiment 16 The adhesive composition according to Embodiment 12 or 13, wherein the tertiary amine comprises an aromatic ring and an acrylate.

[0027] Embodiment 17 The adhesive composition according to Embodiment 12 or 13, wherein the tertiary amine comprises an aromatic ring having a 1-3 tertiary amine functional group and optionally further comprises at least one hydroxyl substituent.

[0028] Embodiment 18 The adhesive composition according to Embodiment 12 or 13, wherein the tertiary amine comprises one or more mono-, di-, or tris-(dialkylaminomethyl)-phenols.

[0029] Embodiment 19 The adhesive composition according to Embodiment 12 or 13, wherein the tertiary amine comprises 2,4,6-tris-(dimethylaminomethyl)-phenol.

[0030] Embodiment 20 An adhesive composition according to any one of the prior embodiments, comprising about 0.5 to about 5% by weight of the latent reactant based on the weight of the composition.

[0031] Embodiment 21 The adhesive composition according to any one of the prior embodiments, wherein the modified urea accelerator comprises dimethylurea.

[0032] Embodiment 22 An adhesive composition according to any one of the prior embodiments, comprising about 0.2 to about 3% by weight of the modified urea accelerator based on the weight of the composition.

[0033] Embodiment 23 An adhesive composition according to any one of the prior embodiments, comprising about 2 to about 6% by weight of the dicyandiamide based on the weight of the composition.

[0034] Embodiment 24 The adhesive composition according to any one of the preceding embodiments, wherein the reinforcing agent comprises at least one carboxyl-terminated butadiene acrylonitrile (CTBN), and optionally has DGEBF and / or DGEBA added.

[0035] Embodiment 25 The adhesive composition according to Embodiment 24, comprising about 1 to about 20% by weight of the reinforcing agent based on the weight of the composition.

[0036] Embodiment 26 An adhesive composition according to any one of the prior embodiments, further comprising a core-shell rubber (CSR) particle solid reinforcing agent optionally dispersed in an epoxy resin.

[0037] Embodiment 27 The adhesive composition according to specific embodiment 26, wherein the CSR particles are nanocore-shell rubber particles.

[0038] Embodiment 28 The adhesive composition according to embodiment 26 or 27, wherein the CSR particles are dispersed in DGEBA.

[0039] Embodiment 29 The adhesive composition according to Embodiment 28, comprising approximately 40 to approximately 45% by weight of CSR particles, based on the weight of CSR particles in DGEBA.

[0040] Embodiment 30 An adhesive composition according to any one of embodiments 26 to 29, comprising about 20 to about 25% by weight of CSR particles based on the weight of the composition.

[0041] Embodiment 31 The adhesive composition according to any one of the prior embodiments, further comprising a softening agent, wherein the softening agent is a polyetheramine-DGEBA adduct.

[0042] Embodiment 32 An adhesive composition according to any one of the prior embodiments, comprising a polyurethane reinforcing agent.

[0043] Embodiment 33 The adhesive composition according to a specific embodiment 32, wherein the polyurethane reinforcing agent is a block-type polyurethane reinforcing agent.

[0044] Embodiment 34 The adhesive composition according to Embodiment 32 or 33, wherein the reinforcing agent comprises one or more optionally end-capacitated polyurethane prepolymers based on (poly(tetramethylene ether) glycol and / or polybutadiene).

[0045] Embodiment 35 An adhesive composition according to any one of embodiments 32 to 34, comprising about 0.1 to about 34% by weight of the polyurethane reinforcing agent based on the weight of the composition.

[0046] Embodiment 36 An adhesive composition according to any one of embodiments 32 to 35, comprising about 2 to about 30% by weight of the polyurethane reinforcing agent based on the weight of the composition.

[0047] Embodiment 37 An adhesive composition according to any one of the prior embodiments, further comprising a phosphorus-based adhesion promoter.

[0048] Embodiment 38 The adhesive composition according to Embodiment 37, wherein the phosphorus-based adhesion promoter comprises substituted or unsubstituted triphenyl phosphate.

[0049] Embodiment 39 The adhesive composition according to Embodiment 37, wherein the phosphorus-based adhesion promoter comprises at least one tris(alkylphenyl) phosphate.

[0050] Embodiment 40 The adhesive composition according to Embodiment 37, wherein the phosphorus-based adhesion promoter comprises one or more tris(4-isopropylphenyl)phosphate, tris[4-(2-methylpropyl)phenyl]phosphate, or triphenyl phosphate.

[0051] Embodiment 41 An adhesive composition according to any one of embodiments 37 to 40, comprising about 0.5 to about 5% by weight of the phosphorus-based adhesion promoter based on the weight of the composition.

[0052] Embodiment 42 An adhesive composition according to any one of the prior embodiments, further comprising a silane adhesion promoter.

[0053] Embodiment 43 The adhesive composition according to specific embodiment 42, wherein the silane adhesion promoter is 3-glycidyloxypropyltrimethoxysilane (GLYMO).

[0054] Embodiment 44 The adhesive composition according to Embodiment 42 or 43, comprising about 0.1 to about 0.3% by weight of the silane adhesion promoter based on the weight of the composition.

[0055] Embodiment 45 The adhesive composition according to any one of the prior embodiments, wherein the filler is an inorganic filler.

[0056] Embodiment 46 The inorganic filler is a desiccant, a thixotrope, or a combination thereof, as described in the adhesive composition according to a specific embodiment 45.

[0057] Embodiment 47 The adhesive composition according to specific embodiment 45 or 46, wherein the inorganic filler is calcium oxide, calcium metasilicate, mica, mixed mineral thixotrope, hydrophobic surface-treated fumed silica, hollow glass microspheres, or a combination thereof.

[0058] Embodiment 48 An adhesive composition according to any one of embodiments 45 to 47, comprising about 1 to about 35% by weight of the inorganic filler based on the weight of the composition.

[0059] Embodiment 49 An adhesive composition according to any one of embodiments 45 to 47, comprising about 1 to about 10% by weight of calcium oxide based on the weight of the composition.

[0060] Embodiment 50 An adhesive composition according to any one of the prior embodiments, comprising about 1 to about 10% by weight of calcium metasilicate based on the weight of the composition.

[0061] Embodiment 51 An adhesive composition according to any one of embodiments 45 to 47, comprising about 0.1 to about 1% by weight of mica based on the weight of the composition.

[0062] Embodiment 52 An adhesive composition according to any one of embodiments 45 to 47, comprising about 0.1 to about 1% by weight of mixed mineral thixotrope based on the weight of the composition.

[0063] Embodiment 53 An adhesive composition according to any one of embodiments 45 to 47, comprising about 1 to about 8% by weight of hydrophobic surface-treated fumed silica based on the weight of the composition.

[0064] Embodiment 54 An adhesive composition according to any one of embodiments 45 to 47, comprising about 0.5 to about 3% by weight of hollow glass microspheres based on the weight of the composition.

[0065] Embodiment 55 The adhesive composition according to any one of the prior embodiments, wherein the epoxy resin different from (i) is a novolac epoxy resin having an EEW in the range of 172 to 225.

[0066] Embodiment 56 The adhesive composition according to any one of the preceding embodiments, wherein the adhesive composition does not contain an accelerator which is imidazole, dihydroxybenzene, adipic anhydride, phosphonium ionic liquid, acrylate-free phenolic blocked tertiary amine, polyamine salt of a polyhydric phenol, or a combination thereof.

[0067] Embodiment 57 An adhesive composition according to any one of the prior embodiments, which is storage stable at room temperature and preferably stable in the range of 15°C to 30°C.

[0068] Embodiment 58 A method for producing a cured adhesive, comprising heating an adhesive composition described in any one of the prior embodiments to a temperature of about 140°C to about 150°C.

[0069] Embodiment 59 The method according to claim 58, wherein the adhesive composition is heated at approximately 140°C for 15 minutes.

[0070] Embodiment 60 The method according to claim 58 or 59, further comprising heating at 190°C for 60 minutes.

[0071] Embodiment 61 A product manufactured using the method described in any one of claims 58 to 60.

[0072] Embodiment 62 A product comprising a first surface and a second surface, wherein a cured layer of the adhesive composition according to any one of claims 1 to 57 is sandwiched between the first surface and the second surface and bonded them together.

[0073] Embodiment 63 The product according to claim 62, wherein one or both of the first surface and the second surface include a metal surface, a composite surface, or a combination thereof.

[0074] Embodiment 64 The product according to claim 62, wherein one or both of the first surface and the second surface include a metal, coated metal, aluminum, plastic, filled plastic, or fiberglass surface.

[0075] Embodiment 65 A steel or aluminum surface containing the adhesive composition according to any one of claims 1 to 57.

[0076] Embodiment 66 The steel or aluminum surface according to claim 65, wherein the adhesive composition is bonded to the surface.

[0077] Embodiment 67 A steel or aluminum surface according to claim 65, which is a part of an aircraft, automobile, ship, locomotive, or construction vehicle, preferably an automobile part.

[0078] In some embodiments, the present disclosure provides adhesive compositions comprising (i) an epoxy resin comprising a substituted or unsubstituted bisphenol diglycidyl ether; (ii) a latent reagent; (iii) a modified urea accelerator; (iv) a dicyandiamide; (v) at least one reinforcing agent; (vi) optionally at least one filler; and (vii) optionally an epoxy resin different from (i).

[0079] In other embodiments, the Disclosure provides a method for producing a cured adhesive, comprising heating the adhesive composition described herein to a temperature of about 140°C to about 190°C, preferably at least, in preferred order, about 135°C, 136°C, 137°C, 138°C, 139°C, 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, or 150°C.

[0080] In further embodiments, the Disclosure provides products manufactured using the methods described herein. In yet another embodiment, the Disclosure provides metal surfaces such as steel, galvanized or aluminum surfaces comprising the adhesive compositions described herein. [Brief explanation of the drawing]

[0081] [Figure 1] Figure 1 is a line graph showing the degree of hardening as a function of time for Examples 1 to 4. [Figure 2] Figure 2A shows the dynamic mechanical analysis (DMA) of Example 2 and Example 4 after high-temperature firing (HB) curing. [Figure 3] Figure 3 is a line graph showing the degree of hardening as a function of time for Examples 2, 5, and 6. [Figure 4] Figure 4 is a line graph showing the degree of hardening as a function of time for Examples 2, 7, and 8. [Figure 5]Figure 5A shows the DMA results after HB curing for Examples 2 and 4, and Figure 5B shows the DMA results after HB curing for Examples 2 and 8. [Figure 6] Figure 6 is a line graph showing the degree of hardening as a function of time for Examples 9, 10, and 11. [Modes for carrying out the invention]

[0082] The subject matter of the inventions of this disclosure will be more readily understood by referring to the following detailed description in conjunction with the accompanying drawings and examples that constitute part of this disclosure. It should be understood that these inventions are not limited to the specific components, methods, or parameters described and / or illustrated herein. Furthermore, it should be understood that the terms used herein are for illustrative purposes only and do not limit the inventions described in the claims.

[0083] The epoxy adhesive compositions described herein offer one or more of the significant improvements described above. In some embodiments, the compositions have storage stability and heat-cur over a wide range of time / temperature conditions (curing range), preferably at both extreme "edges" of the curing range in question. For example, the compositions can be cured preferably by low-temperature firing (140°C for 15 minutes) or high-temperature firing (190°C for 60 minutes), and can exhibit good overlap shear properties, T-type peel properties, and / or impact properties, preferably even at low temperatures, such as -30°C, and even -40°C. This is an improvement over currently available 1K impact-resistant adhesives, which require a minimum time / temperature curing condition of 10 minutes at 155°C to 160°C, and whose performance is adversely affected by over-firing, such as 60 minutes at 190°C. In other embodiments, the compositions exhibit good reactivity at 140°C and good storage stability. This is in contrast to known epoxy adhesive compositions that, when heat-cured at low temperatures such as 140°C for 15 minutes, do not fully cure and do not exhibit "full-spectrum" impact properties.

[0084] Furthermore, surprisingly, it was found that the combination of low concentrations of latent reagents and modified urea accelerators yielded desirable curing rates, storage stability, network properties encompassing the glass transition temperature (Tg), good T-type peel adhesion, lap shear adhesion, and / or impact properties across the entire extended curing region of interest.

[0085] Adhesive composition This specification provides a novel adhesive composition that exhibits improved storage stability and reactivity, as described herein.

[0086] The disclosure provides an adhesive composition comprising an epoxy resin containing a substituted or unsubstituted bisphenol diglycidyl ether, a latent reactant, a modified urea accelerator, a dicyandiamide; at least one reinforcing agent, any at least one filler, and any epoxy resin different from (i).

[0087] The adhesive compositions described herein are storage stable at "room temperature," i.e., around room temperature of about 15 to about 25°C, for example, about 20°C or 23°C. The stability of the adhesive compositions can be measured using the art of those skilled in the art. Generally, accelerated aging techniques (e.g., heating the adhesive to a temperature higher than room temperature but lower than the reaction initiation temperature) are used to determine the storage life at room temperature by known methods. For example, the viscosity of the adhesive composition can be measured using parallel plate rheology (5000 Pa·s, 15°C, constant shear rate 3s). -1 It can be measured using techniques such as (values ​​over 180 seconds), and it is possible to determine whether an acceptable viscosity is maintained after aging conditions of 7 days at 35-40°C, or other appropriate time / temperature conditions.

[0088] A. Epoxy resin According to this disclosure, the adhesive composition contains an epoxy resin comprising a diglycidyl ether of a substituted or unsubstituted bisphenol. In some embodiments, the epoxy resin comprises a diglycidyl ether of a substituted bisphenol. In other embodiments, the epoxy resin comprises a diglycidyl ether of an unsubstituted bisphenol. In further embodiments, the epoxy resin may be a diglycidyl ether of bisphenol A (DGEBA), a diglycidyl ether of bisphenol F (DGEBF), or a combination thereof. Other polyphenols suitable as a base for the polyglycidyl ether are known condensation products of novolac resin-type phenols with formaldehyde or acetaldehyde. In some embodiments, the epoxy resin may be a liquid epoxy resin obtained by the reaction of bisphenol A or bisphenol F with epichlorohydrin. Epoxy resins that are liquid at room temperature generally have an epoxy equivalent of about 150 to about 480. In other embodiments, one or more bisphenol A diglycidyl ether (DGEBA) epoxy resins or bisphenol F diglycidyl ether (DGEBF) epoxy resins may be used alone or in combination. Suitable commercially available polyphenol polyglycidyl ether products include bisphenol A diglycidyl ether resins (including the 300 and 600 series) sold by Orin under the trade name DER®, or products such as Epon 828 and Kukdo YD-128. Other aliphatic epoxy diluents / softeners from the DER® 700 series may also be added to reduce viscosity (i.e., as a diluent), increase flexibility / elongation, or improve adhesion.

[0089] The epoxy resin may have an epoxy equivalent weight (EEW) determined according to formula I.

[0090] [ka]

[0091] In some embodiments, the epoxy resin preferably has an EEW of at least about 125, 150, 160, 170, 180, and independently preferably about 190, 200, 210, 220, 230, 235, 240, or 250 or less. In other embodiments, the epoxy resin has an EEW of about 150 to about 225 or about 170 to about 200. In further embodiments, the epoxy resin has an EEW of about 185 to about 192. In other embodiments, the epoxy resin has an EEW of about 172 to about 179.

[0092] The adhesive composition may contain epoxy resin in an amount of about 30% to about 60% by weight, based on the weight of the composition. In some embodiments, the adhesive composition contains epoxy resin in an amount of about 30% by weight, about 35% by weight, about 40% by weight, about 45% by weight, about 50% by weight, about 55% by weight, or about 60% by weight, based on the weight of the composition. In other embodiments, the adhesive composition contains, based on the weight of the composition, about 30 to about 55% by weight, about 30 to about 50% by weight, about 30 to about 45% by weight, about 30 to about 40% by weight, about 30 to about 35% by weight, about 35 to about 60% by weight, about 35 to about 55% by weight, about 35 to about 50% by weight, about 35 to about 45% by weight, about 35 to about 40% by weight, about 40 to about 60% by weight, about 40 to about 55% by weight, about 40 to about 50% by weight, about 40 to about 45% by weight, about 40 to about 45% by weight, about 45 to about 60% by weight, about 45 to about 55% by weight, about 45 to about 50% by weight, about 50 to about 60% by weight, or about 55 to about 60% by weight of epoxy resin.

[0093] B. Latent Reactive Agents The adhesive composition also contains a heat-activatable latent reagent. In this specification, the term “latent reagent” refers to a reagent that reacts with or promotes reactions between other components of the adhesive composition when subjected to changes in temperature, pH, or solubility. These reagents are sometimes referred to as catalysts or accelerators in the literature. Unlike “B. Latent Reagent” described herein (C. Modified Urea Accelerator), in preferred embodiments, both “B” and “C” are present in the epoxy adhesive composition.

[0094] The term “thermally activated reagent” refers to a chemical reagent that, when exposed to a predetermined temperature as described herein, reacts with or promotes reactions between other components of the adhesive composition. In the epoxy adhesive of the present invention, the desired curing temperature is about 140°C, but may be lower, as long as the adhesive performance and room temperature storage stability are not unacceptably reduced. The reaction initiation temperature may be in the range of about 130°C to 138°C, if at least a portion of the latent reagent is activated below that temperature. In some embodiments, the latent reagent may be a thermally activated reagent containing, for example, a blocked, encapsulated, or reversibly inactivated latent tertiary amine. The latent reagent is preferably thermally activated in the temperature range of about 100, 110, 120, 125, or 130°C, in at least preferred order, and more preferably in the temperature range up to about 131, 132, 133, 134, 135, 136, 137, or 138°C. The latent reagent preferably contains a modified polymer tertiary amine. In preferred embodiments, the latent reagent comprises a tertiary amine, a polyhydroxyphenylalkyl polymer or resin (e.g., a novolac resin), and an auxiliary organic agent. In one embodiment, the auxiliary organic agent may comprise an oligomer or polymer (e.g., an acrylic polymer) containing an acrylic portion. In this specification, the term "acrylic" refers to an α,β-unsaturated carbonyl compound, i.e., a compound containing a carbon-carbon double bond and a carbon-oxygen double bond separated by a carbon-carbon single bond. In certain embodiments, acrylic may be an acrylate, i.e., CH2=CHC(O)O-. In other embodiments, acrylic may be an acryloyl group, i.e., CH2=CHC(O)-. In further embodiments, acrylic may be a polymer or copolymer of phenols substituted with unsaturated ethylene groups, such as 2-allylphenol and 4-allylphenol, as described in U.S. Patent No. 9,546,243, or a polymer and copolymer of phenol-substituted acrylates or phenol-substituted methacrylates, or a polymer of vinylphenol and propenylphenol.Suitable phenolic resins may also include copolymers of these unsaturated phenols with other polymerizable alkene-substituted compounds such as styrene, γ-methylstyrene, acrylic acid esters, methacrylic acid esters, and vinyl esters. Examples of latent reagents include, but are not limited to, Technicure LC-100, described as a modified polymeric tertiary amine with an average particle size of 10 μm and a MP of 90-100°C, and compositions containing Ancamin® K54, which is 2,4,6-tris-(dimethylaminomethyl)-phenol, and Albonol® PN320, which is a phenolic resin.

[0095] The tertiary amine comprises at least one hydroxyl substituent. In some embodiments, the tertiary amine may comprise an aromatic ring and an acrylate. As used herein, the term “aromatic ring” refers to an optionally substituted phenyl ring. In some embodiments, the tertiary amine comprises an aromatic ring having 1 to 3 tertiary amine functional groups, and optionally further comprises at least one hydroxyl substituent. In further embodiments, the tertiary amine may comprise one or more mono-, di-, or tris-(dialkylaminomethyl)-phenols. In other embodiments, the tertiary amine comprises 2,4,6-tris-(dimethylaminomethyl)-phenol. In yet another embodiment, the latent reagent may be Ancamin® 2920 (Evonik), described by the manufacturer as an encapsulation accelerator comprising a tertiary amine, a polyhydroxyphenylalkyl polymer, and an acrylic polymer. In certain embodiments, the latent reagent component contains about 25 to about 50% by weight of the tertiary amine. In other embodiments, the latent reagent contains about 25 to about 50% by weight of the polyhydroxyphenylalkyl polymer. In further embodiments, the latent reagent contains about 25 to about 50% by weight of an acrylic polymer.

[0096] The adhesive composition preferably contains, based on the weight of the composition, about 0.25 to about 3% by weight of the latent reagent described herein as an encapsulation accelerator comprising a tertiary amine, a polyhydroxyphenylalkyl polymer, and an acrylic polymer. In other embodiments, the adhesive composition contains, based on the weight of the composition, at least about 0.5% by weight, 1% by weight, 1.5% by weight, or 2% by weight, in preferred order, and about 5% by weight, 4.5% by weight, 4% by weight, 3.5% by weight, 3% by weight, 2.5% by weight, or 2.25% by weight or less. For example, the latent reagent containing the epoxyamine adduct is preferably present in an amount of about 5.0 to about 3.0, about 5.0 to about 3.5, about 5.0 to about 4.0, about 4.75 to about 2.5, about 4.75 to about 3.0, about 4.75 to about 3.5, about 4.75 to about 3.75, about 4.5 to about 3.5, and about 4.5 to about 3.75% by weight of the latent reagent. In further embodiments, the adhesive composition contains about 2 to about 3.5% by weight of the latent reagent, based on the weight of the composition.

[0097] In some embodiments, latent reagents may be prepared according to methods known in the art (see U.S. Patents 9000120 and 9546243). For example, a novolac resin or other polyphenol resin is heated and dissolved in a tertiary amine (optionally in the presence of an acrylate oligomer or polymer), and then cooled. The resulting solid solution of the components may then be ground to a desired particle size.

[0098] C. Modified urea promoter The epoxy adhesive composition contains a modified urea accelerator. As used herein, the term "modified urea" refers to a compound containing a urea group with substituents at one or more positions in the molecule, i.e., NH2C(O)NH2. Typically, one or more hydrogens bonded to the urea nitrogen atom are substituted with identical or different alkyl or aryl groups. In some embodiments, the modified urea accelerator is methylated urea. In other embodiments, the modified urea accelerator includes dimethylurea, such as 1,1-dimethylurea, (CH3)2NC(O)NH2, 1,3-dimethylurea, 4,4'-methylenebis-(phenyldimethylurea), aryldimethylurea compounds such as diurone and monulone, alicyclic dimethylurea, or aliphatic dimethylurea. In further embodiments, the modified urea accelerator is dimethylurea.

[0099] In certain embodiments, the denatured urea accelerator may be dimethylurea, and the latent reagent may be Ancamin® 2920.

[0100] The adhesive composition contains about 0.2 to about 3% by weight of a modified urea accelerator, based on the weight of the composition. In some embodiments, the adhesive composition contains about 0.2% by weight, 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, or 3% by weight of a modified urea accelerator, based on the weight of the composition. In other embodiments, the adhesive composition contains, based on the weight of the composition, about 0.2 to about 3% by weight, about 0.2 to about 2.5% by weight, about 0.2 to about 2% by weight, about 0.2 to about 1.5% by weight, about 0.2 to about 1% by weight, about 0.2 to about 0.5% by weight, about 0.5 to about 3% by weight, about 0.5 to about 2.5% by weight, about 0.5 to about 2% by weight, about 0.5 to about 1.5% by weight, about 0.5 to about 1% by weight, about 1 to about 3% by weight, about 1 to about 2.5% by weight, about 1 to about 2% by weight, about 1 to about 1.5% by weight, about 1.5 to about 3% by weight, about 1.5 to about 2.5% by weight, about 1.5 to about 2% by weight, about 1.5 to about 2% by weight, about 2 to about 3% by weight, about 2 to about 2.5% by weight, or about 2.5 to about 3% by weight of a modified urea accelerator. In further embodiments, the adhesive composition contains about 0.2 to about 1% by weight of a modified urea accelerator, based on the weight of the composition.

[0101] D. Dicyandiamide According to this disclosure, adhesive compositions contain a curing agent such as dicyandiamide (DICY). The adhesive composition may be a one-component or one-part composition and contains one or more curing agents, and / or latent reactants and / or accelerators, which, when the adhesive is heated to the activation temperature of the curing agent, can achieve crosslinking or curing of specific adhesive components. To ensure good storage stability of one-component epoxy adhesives, the DICY curing agent has low solubility in epoxy resin at room temperature and is latent until heated. Solid finely ground curing agents can be readily dissolved near the activation temperature, and dicyandiamide (DICY) is particularly preferred. In certain embodiments, the DICY in the liquid epoxy adhesive composition may contain finely ground dicyandiamide (cyanoguanidine). Since DICY is insoluble in epoxy resin before melting, the use of finely ground dicyandiamide ensures the reactivity of DICY with epoxy during and after melting. In certain embodiments, at least 98% of the finely ground dicyandiamide has a particle size of 40 μm or less. In other embodiments, at least 98% of the finely powdered dicyandiamide has a particle size of 10 μm or less. In other embodiments, at least 98% of the finely powdered dicyandiamide has a particle size of 6 μm or less. Such materials are commercially available from AlzChem under the trade name Diehard®.

[0102] In some embodiments, the adhesive composition contains about 2 to about 5.5% by weight of DICY, based on the weight of the composition. In other embodiments, the adhesive composition contains, in preferred order, at least about 1.5%, 1.75%, 2%, 2.5%, or 3% by weight of DICY, based on the weight of the composition, and in preferred order, about 3.5%, 4%, 4.5%, 5%, 5.5%, or 6% by weight or less of DICY. In further embodiments, the adhesive composition is based on the weight of the composition in approximately 2 to approximately 6% by weight, approximately 2 to approximately 5.5% by weight, approximately 2 to approximately 5% by weight, approximately 2 to approximately 4.5% by weight, approximately 2 to approximately 4% by weight, approximately 2 to approximately 3.5% by weight, approximately 2 to approximately 3% by weight, approximately 2 to approximately 2.5% by weight, approximately 2.5 to approximately 6% by weight, approximately 2.5 to approximately 5.5% by weight, approximately 2.5 to approximately 5% by weight, approximately 2.5 to approximately 4.5% by weight, approximately 2.5 to approximately 4% by weight, approximately 2.5 to approximately 3.5% by weight, approximately 2.5 to approximately 3% by weight, approximately 3 to approximately 6% by weight, approximately 3 to approximately 5.5% by weight, and approximately 3 The adhesive composition contains approximately 5% by weight, approximately 3-4.5% by weight, approximately 3-4% by weight, approximately 3-3.5% by weight, approximately 3.5-6% by weight, approximately 3.5-5.5% by weight, approximately 3.5-5% by weight, approximately 3.5-4.5% by weight, approximately 3.5-4% by weight, approximately 4-6% by weight, approximately 4-5.5% by weight, approximately 4-4.5% by weight, approximately 4.5-5.5% by weight, approximately 4.5-5.5% by weight, approximately 4.5-5.5% by weight, approximately 5-6% by weight, approximately 5-5.5% by weight, or approximately 5.5-6% by weight of DICY. In further embodiments, the adhesive composition contains approximately 2-5.5% by weight of DICY based on the weight of the composition. In yet another embodiment, the adhesive composition contains approximately 3-4% by weight of DICY based on the weight of the composition.

[0103] E. At least one reinforcing agent The adhesive compositions described herein also contain at least one reinforcing agent, preferably more than one. The total amount of reinforcing agents may range from 15% to 40% by weight, depending on the selected reinforcing component. In some embodiments, the reinforcing agents include at least one carboxyl-terminated butadiene acrylonitrile (CTBN), at least one polyurethane prepolymer, and optionally core-shell rubber (solid reinforcing agent). In other embodiments, the reinforcing agents include one or more polyurethane prepolymers based on poly(tetramethylene ether) glycol and / or polybutadiene, which may be end-capped.

[0104] Carboxylate-terminated butadiene acrylonitrile (CTBN reinforcing agent) The adhesive compositions described herein may also contain at least one reinforcing agent, preferably more than one. In some embodiments, the reinforcing agent comprises at least one carboxyl-terminated butadiene acrylonitrile (CTBN) to which DGEBF and / or DGEBA are optionally added. In other embodiments, the CTBN may comprise a copolymer of butadiene and a nitrile monomer such as acrylonitrile, or a homopolymer of butadiene. When the acrylonitrile content is high, it may be in the range of about 22 to about 30% by weight based on the weight of the CTBN, and in preferred embodiments, the CTBN composition contains about 26% by weight of acrylonitrile, which improves the miscibility between the CTBN adduct and the epoxy resin. In certain embodiments, improved solubility delays the onset (rate) of phase separation during curing, resulting in a reduction in the size of the rubber domains and improved fracture toughness. Preferably, at least a portion of the CTBN reinforcing agent does not phase separate into rubber domains but remains dispersed in the epoxy matrix, imparting flexibility to the cured matrix.

[0105] Carboxylated butadiene acrylonitrile (CTBN) has a functional value of about 1.5, or about 1.8 to about 2.5, or about 2.2, and an acrylonitrile content in the range of about 20 to about 28%, or about 26%. The molecular weight (Mn) of the butadiene acrylonitrile copolymer is preferably about 2000 to about 6000, for example, about 3000 to about 5000. Suitable carboxylated functional butadienes and butadiene / acrylonitrile copolymers are commercially available from Huntsman under the trademarks Hycar® and Hypro®. In some embodiments, DGEBA or DGEBF may be added to a portion of one or more carboxylated butadiene acrylonitrile (CTBN). See suitable adducts commercially available from Huntsman under the trademark Hypox®. The adducts may be dissolved or dispersed in a novolac epoxy resin to enhance solubility. In other embodiments, CTBN may be a CTBN-DGEBF adduct in an epoxy resin. In further embodiments, CTBN may be dissolved in DGEBF as needed.

[0106] In some embodiments, the adhesive composition contains about 1 to about 20% by weight of a reinforcing agent, based on the weight of the composition. In other embodiments, the adhesive composition contains about 1% by weight, about 2% by weight, about 3% by weight, about 4% by weight, about 5% by weight, about 6% by weight, about 7% by weight, about 8% by weight, about 9% by weight, about 10% by weight, about 11% by weight, about 12% by weight, about 13% by weight, about 14% by weight, about 15% by weight, about 16% by weight, about 17% by weight, about 18% by weight, about 19% by weight, or about 20% by weight of a reinforcing agent, based on the weight of the composition. In further embodiments, the adhesive composition contains, based on the weight of the composition, about 1 to about 15% by weight, about 1 to about 10% by weight, about 1 to about 5% by weight, about 5 to about 20% by weight, about 5 to about 15% by weight, about 5 to about 10% by weight, about 10 to about 20% by weight, about 10 to about 15% by weight, or about 15 to about 20% by weight of the reinforcing agent. In yet another embodiment, the adhesive composition contains, based on the weight of the composition, about 5 to about 10% by weight of the reinforcing agent.

[0107] Core-shell rubber (CSR) particles (solid reinforcing agent) The adhesive composition may contain core-shell rubber (CSR) particles, which may optionally be dispersed in an epoxy resin. See, for example, U.S. Patent No. 8,673,108 incorporated herein. Core-shell rubber (CSR) particles generally have a core made of a polymer material having elastomer or rubber properties (i.e., a glass transition temperature less than about 0°C, e.g., less than about -30°C) surrounded by a shell made of a non-elastomer polymer material (i.e., a thermoplastic or thermosetting / crosslinked polymer with a glass transition temperature higher than room temperature, e.g., above about 50°C), as measured by differential scanning calorimetry (DSC). The rubber core may account for about 50 to about 90%, for example, about 50 to about 85%, of the weight of the core-shell rubber particles.

[0108] In some embodiments, the average particle diameter of the CSR particles is less than approximately 500 nm. In yet other embodiments, the average particle diameter of the CSR particles is greater than approximately 500 nm. For example, the average particle diameter may be approximately 0.03 to approximately 2 μm, or approximately 0.05 to approximately 1 μm. The average diameter of the rubber particles is preferably less than approximately 500 nm. In other embodiments, the average particle diameter is less than approximately 200 nm. For example, the average diameter of the rubber particles may be approximately 25 to approximately 200 nm, or approximately 50 to approximately 150 nm. The core-shell rubber particles may have a number-average particle diameter (diameter) measured by transmission electron spectroscopy of approximately 10 to approximately 300 nm, or for example, approximately 75 to approximately 250 nm (i.e., "nanocore-shell rubber particles").

[0109] The core may consist of a diene homopolymer or copolymer of monomers containing one or more ethylenically unsaturated monomers such as butadiene, isoprene, vinyl aromatic monomers, (meth)acrylonitrile, or (meth)acrylate, or polybutadiene core particles. Other suitable rubbery core polymers include polybutyl acrylate or polysiloxane elastomers (e.g., polydimethylsiloxane).

[0110] The shell may consist of a polymer or copolymer of one or more monomers with a moderately high glass transition temperature, such as (meth)acrylate (e.g., methyl methacrylate), vinyl aromatic monomer (e.g., styrene), vinyl cyanide (e.g., acrylonitrile), unsaturated acids and anhydrides (e.g., acrylic acid), (meth)acrylamide, or acrylates, particularly poly(methyl methacrylate). The shell polymer or copolymer may be crosslinked and / or have one or more different types of functional groups (e.g., carboxylic acid groups or epoxy groups) that can interact with other components of the adhesive. In one embodiment, the shell polymer may be polymerized from at least one lower alkyl methacrylate, such as methyl methacrylate, ethyl methacrylate, or t-butyl methacrylate. Up to 40% by weight of the shell polymer may be formed from other monovinylidene monomers such as styrene, vinyl acetate, vinyl chloride, methyl acrylate, ethyl acrylate, or butyl acrylate. The shell polymer may be a homopolymer of any of these lower alkyl methacrylate monomers. The molecular weight (Mn) of the graft shell polymer may generally be between 20,000 and 500,000. The rubber particles may consist of two or more layers (for example, a central core rubber-like material may be surrounded by a rubber-like material different from the shell, or there may be two shells, or a hard shell, a soft shell, and another hard shell). The shells may be grafted onto the core.

[0111] CSR particles may be prepared as a masterbatch in which rubber particles are dispersed in one or more epoxy resins, such as diglycidyl ether of bisphenol A. Optionally, the masterbatch can be allowed to mature at room temperature, resulting in little to no particle aggregation or precipitation, and maintaining the individual particles' separation. Core-shell rubber particles may be provided as a dispersion in an epoxy resin or phenol resin matrix. Such a dispersion may contain, for example, about 5 to about 50% (about 15 to about 40% by weight) of core-shell rubber, with the remainder being epoxy resin. The epoxy resin in such a dispersion may be the aforementioned polyglycidyl polyphenol ether. The matrix material may be liquid at room temperature. Examples of epoxy matrices include diglycidyl ether of bisphenol A, F, or S, or bisphenol, novolac epoxy, and alicyclic epoxy. Examples of phenol resins include bisphenol A-based phenoxy resins. One commercially available dispersion containing rubber particles having a core-shell structure dispersed in an epoxy resin matrix is ​​sold by Kaneka Corporation under the trade name "ACE MX," which is described as having a polybutadiene core or a (meth)acrylate-butadiene-styrene copolymer core, with butadiene dispersed in the epoxy resin as the main component of the phase-separated particles. When core-shell rubber particles are provided in the form of such a dispersion, only the weight of the core-shell rubber particles is counted as the core-shell rubber component in this disclosure. Methods for manufacturing masterbatches are described in European Patent No. 1,632,533, U.S. Patent No. 4,778,851, and U.S. Patent No. 6,111,015, which are incorporated herein by reference in their entirety.

[0112] Examples of CSR particles suitable for use in this composition include the following commercially available products: the Paraloid EXL2600 / 3600 series (styrene / methyl methacrylate copolymer grafted onto a polybutadiene core, average particle size 0.1-0.3 μm) from Rohm & Haas; Degaran (trademark) from Rohm or Rohm America; F351 (trademark) from Zeon Corporation; Geniopal (trademark) powder from Wacker Chemie (according to the supplier, it has a cross-linked polysiloxane core, epoxy-functionalized polymethyl methacrylate shell, and a polysiloxane content of approximately 65% ​​by weight); and Kaneka's KaneAce MX-153, MX-154, MX-257 and MX-EXP-EH2 (KaneAce MX-160).

[0113] In the present invention, combinations of different core-shell rubber particles can be advantageously used. The core-shell rubber particles may differ, for example, in particle size, glass transition temperature of each core and / or shell, composition of the polymer used for each core and / or shell, functionalization of each shell, etc. Some of the core-shell particles can be supplied to the adhesive composition in the form of a masterbatch in which the particles are stably dispersed in an epoxy resin matrix, and other parts can be supplied to the adhesive composition in the form of a dry powder (i.e., a form that does not contain epoxy resin or other matrix material). For example, an adhesive composition can be prepared using both a first type of core-shell particles in the form of a dry powder with an average particle size of about 0.1 to about 0.5 μm and a second type of core-shell particles with an average particle size of about 25 to about 200 nm stably dispersed in a matrix of liquid bisphenol A diglycidyl ether at a concentration of about 5 to about 50% by weight. The weight ratio of the first type of core-shell rubber particles to the second type of core-shell rubber particles may be, for example, about 1.5:1 to about 0.3:1.

[0114] Alternatively, or in combination with CSR, the composition may include rubber particles that do not have a shell surrounding a central core. In such embodiments, the chemical composition of the rubber particles may be essentially uniform throughout each particle, or the outer surface may be modified by irradiation or chemical treatment to promote dispersion into or adhesion to the matrix. A polymer suitable for producing shell-less rubber particles may be selected from any of the polymers described above as suitable as the core of core-shell rubber particles. The polymer may contain functional groups such as carboxyl groups and hydroxyl groups, and may have a linear, branched, crosslinked, random copolymer, or block copolymer structure. Examples of commercially available rubber particles include acrylonitrile / butadiene copolymer, butadiene / styrene / 2-vinylpyridine copolymer, hydroxy-terminated polydimethylsiloxane, and similar elastic solid rubbers. These particles may optionally be surface-modified to generate polar groups (carboxylic acid groups or hydroxyl groups) and / or doped with trace amounts of inorganic substances such as calcium carbonate or silica. This is well known in the art. If the rubber particles do not have a core-shell structure, it is desirable that the average particle size of the rubber particles be less than approximately 750 nm, less than approximately 500 nm, or less than approximately 200 nm. For example, the average particle size of the rubber particles may be in the range of approximately 25 to approximately 200 nm, or approximately 50 to approximately 150 nm.

[0115] In some embodiments of the adhesive composition, core-shell rubber (CSR) particles may be characterized by one or more of the following features: (a) the CSR particles are dispersed in a unimodal or bimodal manner to allow for maximum concentration; the degree of dispersion of the CSR particles may be defined by any suitable means, including sedimentation or visible or automated images of transmission electron microscope (TEM) images; (b) the CSR particles are in a range bounded by an average particle diameter of about 50 nm, about 75 nm, about 100 nm, about 125 nm, about 150 nm, about 175 nm, about 200 nm, about 250 nm, or 500 nm, or any two of the aforementioned values; in yet another embodiment, the rubber particles have a core-shell structure and an average particle diameter greater than about 500 nm; (c) the CSR particles contain, essentially consist of, or have a core made of, polybutadiene, butadiene / styrene copolymer, or acrylic polymer or copolymer; and / or (d) the CSR particles are dispersed in a DGEBA epoxy resin.

[0116] In the compositions of this disclosure, the use of these core-shell rubbers can impart toughness to the formulation regardless of the curing temperature of the formulation. Furthermore, substantially uniform dispersion provides predictable toughness in terms of temperature neutrality with respect to curing.

[0117] The adhesive composition contains about 1 to about 25% by weight of CSR particles. In some embodiments, the adhesive composition contains about 1% by weight, about 5% by weight, about 10% by weight, about 15% by weight, about 20% by weight, or about 25% by weight of CSR particles, based on the weight of the composition. In other embodiments, the adhesive composition contains about 1 to about 20% by weight, about 1 to about 15% by weight, about 1 to about 10% by weight, about 1 to about 5% by weight, about 5 to about 25% by weight, about 5 to about 20% by weight, about 5 to about 15% by weight, about 5 to about 10% by weight, about 10 to about 25% by weight, about 10 to about 20% by weight, about 10 to about 15% by weight, about 15 to about 25% by weight, about 15 to about 20% by weight, or about 20 to about 25% by weight of CSR particles, based on the weight of the composition. In further embodiments, the adhesive composition contains about 10 to about 20% by weight of CSR particles, based on the weight of the composition. In yet another embodiment, the adhesive composition contains about 20 to about 25% by weight of CSR particles, based on the weight of the composition.

[0118] Alternatively, or in addition, the adhesive composition may contain about 1 to about 50% by weight of CSR particles dispersed in DGEBA (CSR content is about 40% or about 45%). In some embodiments, the adhesive composition contains about 1% by weight, about 10% by weight, about 20% by weight, about 30% by weight, about 40% by weight, or about 50% by weight of CSR particles dispersed in DGEBA, based on the weight of the composition. In other embodiments, the adhesive composition contains CSR particles dispersed in DGEBA in amounts of about 1 to about 50% by weight, about 1 to about 40% by weight, about 1 to about 30% by weight, about 1 to about 20% by weight, about 1 to about 10% by weight, about 10 to about 50% by weight, about 10 to about 40% by weight, about 10 to about 30% by weight, about 10 to about 20% by weight, about 20 to about 50% by weight, about 20 to about 40% by weight, about 20 to about 30% by weight, about 30 to about 50% by weight, about 30 to about 40% by weight, or about 40 to about 50% by weight. In further embodiments, the adhesive composition contains CSR particles dispersed in DGEBA in amounts of about 25 to about 44% by weight, based on the weight of the composition. In yet another embodiment, the adhesive composition contains about 20 to about 25% by weight of CSR particles, based on the weight of the composition.

[0119] In further embodiments, core-shell rubber (CSR) particles are identifiable as (a) unimodal or bimodal dispersion, (b) having an average particle diameter within a range bounded by approximately 50 nm, approximately 75 nm, approximately 100 nm, approximately 125 nm, approximately 150 nm, approximately 175 nm, approximately 200 nm, approximately 250 nm, or approximately 500 nm, or any two of the aforementioned values, (c) having a core consisting of or comprising polybutadiene, butadiene / styrene copolymer, or acrylic polymer or copolymer, and / or (d) dispersed in a DGEBA epoxy resin.

[0120] Polyurethane reinforcing agent As described above, the adhesive compositions described herein contain at least one reinforcing agent, which may be based on a polyurethane prepolymer but may not contain CTBN and CSR. In some embodiments, in systems using a polyurethane prepolymer reinforcing component, the total amount of the reinforcing agent is 15 to 25% by weight. In other embodiments, the reinforcing agent comprises one or more polyurethane prepolymers based on poly(tetramethylene ether) glycol and / or polybutadiene, which may be end-capturing.

[0121] In some embodiments, polyurethane reinforcing agents may also provide flexibility based on their polyalkylene glycol portion. See, for example, U.S. Patent No. 8,673,108, which is incorporated herein by reference.

[0122] In certain embodiments, the polyurethane reinforcing agent includes a polyalkylene glycol segment. In some embodiments, the polyalkylene glycol segment independently comprises polyethylene glycol, polypropylene glycol, or polybutylene glycol (or polytetramethylene glycol (polyTHF or PTMEG)) having an equivalent molecular weight in the range of about 2000 to about 5000 daltons, for example, in the range of about 1000 to about 2000 daltons. PTMEG bonding is preferred. In other embodiments, the polyurethane reinforcing agent also includes a polyalkylene (extensioner) segment, for example, the polyalkylene glycol segment is end-capped C 1-10 It is sandwiched between alkylene bonds, or C 6-8 The alkylene bonds are linked by urethane groups.

[0123] In other embodiments, the polyurethane reinforcing agent includes an elastomer reinforcing agent having a sealed isocyanate group. For example, see the following publications incorporated by reference: U.S. Patent No. 5,202,390; U.S. Patent No. 5,278,257; WO2005 / 118734; WO2007 / 003650; WO2012 / 091842, U.S. Patent Application Publication 2005 / 0070634; U.S. Patent Application Publication 2005 / 0209401; U.S. Patent Application Publication 2006 / 0276601; European Patent Nos. 0,308,664, 1,498,441, 1,728,825, 1,896,517, 1,916,269, 1,916,270, 1,916,272, and 1,916,285. These elastomer reinforcing agents are products obtained by reacting an amine or hydroxyl-terminated rubber with a polyisocyanate to form an isocyanate-terminated prepolymer, optionally extending the chain of the prepolymer, and subsequently encapsulating the isocyanate groups with a sealing group. Examples include: a) aliphatic, aromatic, alicyclic, aromaticaliphatic and / or heteroaromatic monoamines having primary or secondary amino groups; b) phenolic compounds such as monophenols, polyphenols, and aminophenols; c) benzyl alcohols which may be substituted with one or more alkyl groups on the aromatic ring; d) hydroxyl-functional acrylate or methacrylate compounds; e) thiol compounds such as alkylthiols having 6 to 16 carbon atoms in the alkyl group (including dodecanethiols); f) alkylamide compounds having at least one amine hydrogen such as acetamide and N-alkylacetamide; and g) ketoximes.

[0124] In further embodiments, one or more block polyurethane reinforcements may be end-sealed at both ends of the structure. The two end-sealing groups of the block polyurethane reinforcement may be the same or different.

[0125] In yet another embodiment, Huntsman's DY965 is an example of a suitable commercially available blocked polyurethane reinforcing agent, with both ends containing bisphenols such as O,O'-diallylbisphenol A. In some cases, the ends are encapsulated with one or more bisphenols, but other encapsulants include optionally substituted phenols (or hydroxyheteroaryl analogs), amines, methacrylates, acetoxys, oximes, and / or pyrazoles. See, for example, Johannes Karl Fink, "High Performance Polymers (2nd Edition)" (2014).

[0126] In further embodiments, the blocked polyurethane reinforcing agent has at least one terminal sealing group derived from methyl ethyl ketone oxime, 2,4-dimethyl-3-pentanone oxime, or 2,6-dimethyl-4-heptanone oxime, diethyl malonate, 3,5-dimethylpyrazole, 1,2,4-triazole, or a mixture of diisopropylamine and 1,2,4-triazole, or a combination thereof. The hydrophobic terminal sealing substituent includes, for example, 1, 2, 3, or 4 conjugated and / or unconjugated alkenylene bonds. 12-24 Further advantages such as pendant functional groups are also expected to be offered. Therefore, in another embodiment, any substituent of phenol (or hydroxyheteroaryl analog), amine, methacrylic, acetoxy, oxime, and / or pyrazole includes such pendant functional groups. In another embodiment, adjacent C 1-10 The alkylene bond has at least one C 12-24 It may be terminally sealed by at least one monophenol containing a pendant functional group, and at least one C 12-24 The pendant functional group contains one, two, three, or four conjugated and / or unconjugated alkenylene bonds. Here again, substituted monophenols are preferred over bisphenols because they are thought to provide a lower curing temperature than bisphenol end-binding. In some embodiments, the polyurethane reinforcing agent may be a phenol polyurethane adduct.

[0127] In preferred embodiments, the polyurethane reinforcing agent comprises one or more bisphenol-terminated polyurethane prepolymers having a MW of about 10-20 K daltons, polyurethane prepolymers asymmetrically end-capped with oximes and hydrophobic monophenol functional groups having a MW of about 10,000 daltons, and polyurethane prepolymers end-capped with hydrophobic monophenol functional groups having a MW of about 2,000.

[0128] The adhesive composition contains about 0.1 to about 34% by weight of polyurethane reinforcing agent, based on the weight of the composition. In some embodiments, the adhesive composition contains about 0.1% by weight, about 0.5% by weight, about 1% by weight, about 2% by weight, about 5% by weight, about 10% by weight, about 15% by weight, about 20% by weight, about 25% by weight, about 30% by weight, or about 34% by weight of polyurethane reinforcing agent, based on the weight of the composition. In other embodiments, the adhesive composition is based on the weight of the composition in approximately 0.1 to approximately 30% by weight, approximately 0.1 to approximately 25% by weight, approximately 0.1 to approximately 20% by weight, approximately 0.1 to approximately 15% by weight, approximately 0.1 to approximately 10% by weight, approximately 0.1 to approximately 5% by weight, approximately 0.1 to approximately 1% by weight, approximately 1 to approximately 34% by weight, approximately 1 to approximately 30% by weight, approximately 1 to approximately 25% by weight, approximately 1 to approximately 20% by weight, approximately 1 to approximately 15% by weight, approximately 1 to approximately 10% by weight, approximately 1 to approximately 5% by weight, approximately 5 to approximately 34% by weight, approximately 5 to approximately 30% by weight, approximately 5 to approximately 25% by weight, The adhesive composition contains 5 to about 20% by weight, about 5 to about 15% by weight, about 5 to about 10% by weight, about 10 to about 34% by weight, about 10 to about 30% by weight, about 10 to about 25% by weight, about 10 to about 20% by weight, about 10 to about 15% by weight, about 15 to about 34% by weight, about 15 to about 30% by weight, about 15 to about 25% by weight, about 15 to about 20% by weight, about 20 to about 34% by weight, about 20 to about 30% by weight, about 20 to about 25% by weight, about 25 to about 34% by weight, about 25 to about 30% by weight, or about 30 to about 34% by weight of polyurethane reinforcing agent. In further embodiments, the adhesive composition contains about 2 to about 30% by weight of polyurethane reinforcing agent based on the weight of the composition. In yet another embodiment, the adhesive composition contains about 2 to about 30% by weight of polyurethane reinforcing agent based on the weight of the composition. In further embodiments, the adhesive composition contains about 5 to about 20% by weight of polyurethane reinforcing agent, based on the weight of the composition. In other embodiments, the adhesive composition contains about 8 to about 12% by weight of polyurethane reinforcing agent, based on the weight of the composition.

[0129] G. Any pliable agent In some embodiments, the adhesive composition may contain one or more emollients. Those skilled in the art can select the emollients. For example, the emollient may be a polyetheramine-DGEBA adduct. The polyetheramine is a terminal-canceled polypropylene glycol having a sufficient number of repeating oxypropylene units in its main chain, characterized by an average weight-average molecular weight of about 1000 to about 3000 daltons, for example, about 2000 daltons. Such materials are commercially available from Huntsman as Jeffamine® polyetheramine. Other examples of emollients, but not limited to these, include dimeric fatty acids; dimeric fatty acid epoxy (DGEBA) adducts; aliphatic, bifunctional and trifunctional epoxy diluents (different from "A. Epoxy Resins"); and solid epoxy resins.

[0130] The adhesive composition may contain about 0.1 to about 14% by weight of a softener, based on the weight of the composition. In some embodiments, the adhesive composition contains about 0.1% by weight, about 0.5% by weight, about 1% by weight, about 2% by weight, about 3% by weight, about 4% by weight, about 5% by weight, about 6% by weight, about 7% by weight, about 8% by weight, about 9% by weight, about 10% by weight, about 11% by weight, or about 12% by weight of a softener, based on the weight of the composition. In other embodiments, the adhesive composition is based on the weight of the composition in approximately 0.1 to 10% by weight, approximately 0.1 to 8% by weight, approximately 0.1 to 6% by weight, approximately 0.1 to 4% by weight, approximately 0.1 to 2% by weight, approximately 0.1 to 1% by weight, approximately 0.5 to 10% by weight, approximately 0.5 to 8% by weight, approximately 0.5 to 6% by weight, approximately 0.5 to 4% by weight, approximately 0.5 to 2% by weight, and approximately 0.5 It contains approximately 1% by weight, approximately 1 to approximately 10% by weight, approximately 1 to approximately 8% by weight, approximately 1 to approximately 6% by weight, approximately 1 to approximately 4% by weight, approximately 1 to approximately 2% by weight, approximately 2 to approximately 10% by weight, approximately 2 to approximately 8% by weight, approximately 2 to approximately 6% by weight, approximately 2 to approximately 4% by weight, approximately 4 to approximately 10% by weight, approximately 4 to approximately 8% by weight, approximately 4 to approximately 6% by weight, approximately 6 to approximately 10% by weight, approximately 6 to approximately 8% by weight, or approximately 8 to approximately 10% by weight of a softening agent.

[0131] H. Any adhesion promoter According to this disclosure, the adhesive composition may further include an adhesion promoter. In certain embodiments, the adhesion promoter may be a flame retardant. In certain embodiments, the flame retardant may be one or more of the following: ammonium polyphosphate, melamine, melamine polyphosphate, phosphonate esters (e.g., diethylbis(hydroxyethyl)aminomethylphosphonate (commercially available as Fyrol® 6-phosphonate ester), halogen-free phosphorus esters (commercially available as Fyrol® HF-9), or any combination thereof.

[0132] An example of a suitable adhesion promoter is a phosphorus-based adhesion promoter. In some embodiments, the phosphorus-based adhesion promoter comprises substituted or unsubstituted triphenyl phosphate. In some embodiments, the phosphorus-based adhesion promoter may be unsubstituted triphenyl phosphate. In further embodiments, the phosphorus-based adhesion promoter may be substituted triphenyl phosphate. In other embodiments, the phosphorus-based adhesion promoter comprises at least one tris(alkylphenyl) phosphate, where alkyl is 1 to 10 carbon atoms, i.e., C 1~10 It contains alkyl groups. Examples include unsubstituted monobutylphenyl phosphate, dibutylphenyl phosphate, and / or tributylphenyl phosphate (e.g., Emerald Innovation NH1). In further embodiments, the phosphorus-based adhesion promoter includes one or more tris(4-isopropylphenyl) phosphate, tris(3-isopropylphenyl) phosphate, tris[4-(2-methylpropyl)phenyl] phosphate, or triphenyl phosphate. In yet another embodiment, the phosphorus-based adhesion promoter may be tris(4-isopropylphenyl) phosphate. In yet another embodiment, the phosphorus-based adhesion promoter may be tris[4-(2-methylpropyl)phenyl] phosphate. In yet another embodiment, the phosphorus-based adhesion promoter may be triphenyl phosphate.

[0133] The adhesive composition contains about 0.5 to about 5% by weight of a phosphorus-based adhesion promoter, based on the weight of the composition. In some embodiments, the adhesive composition contains about 0.5% by weight, about 1% by weight, about 2% by weight, about 3% by weight, about 4% by weight, or about 5% by weight of a phosphorus-based adhesion promoter, based on the weight of the composition. In other embodiments, the adhesive composition contains about 0.5 to about 4% by weight, about 0.5 to about 3% by weight, about 0.5 to about 2% by weight, about 0.5 to about 1% by weight, about 1 to about 55% by weight, about 1 to about 4% by weight, about 1 to about 3% by weight, about 1 to about 2% by weight, about 2 to about 5% by weight, about 2 to about 4% by weight, about 2 to about 3% by weight, about 3 to about 5% by weight, about 3 to about 4% by weight, or about 4 to about 5% by weight of a phosphorus-based adhesion promoter, based on the weight of the composition. In further embodiments, the adhesive composition contains about 2 to about 3% by weight of a phosphorus-based adhesion promoter, based on the weight of the composition.

[0134] Another example of an adhesion promoter is a silane adhesion promoter. In some embodiments, the silane adhesion promoter may be 3-glycidyloxypropyltrimethoxysilane (GLYMO). In some embodiments, the adhesive composition contains about 0.1 to about 0.3% by weight of the silane adhesion promoter, based on the weight of the composition. In other embodiments, the adhesive composition contains about 0.1%, about 0.2%, or about 0.3% by weight of the silane adhesion promoter, based on the weight of the composition. In further embodiments, the adhesive composition contains about 0.1 to about 0.2%, or about 0.2% to about 3% by weight of the silane adhesion promoter, based on the weight of the composition. In yet another embodiment, the adhesive composition contains 0.1 to about 0.2% by weight of the silane adhesion promoter, based on the weight of the composition.

[0135] I. Any filler According to this disclosure, adhesive compositions may contain fillers. Examples of fillers include organic, inorganic, and combinations thereof that can impart structural integrity to the composition before curing. In some embodiments, the filler is an inorganic filler. In certain embodiments, one or more fillers may be present and may include one or more of the following: calcium carbonate, calcium oxide, calcium silicate, aluminosilicate, organic phyllosilicate, bentonite, wollastonite, or natural clays such as kaolin glass, silica, mica, talc, microspheres, or hollow glass microspheres (HGM), chopped or crushed fibers (e.g., carbon, glass, or aramid), pigments, zeolites (natural or synthetic), or thermoplastic fillers. In some embodiments, a single filler may be present, but typically there may be several different fillers, such as two, three, four, or five different fillers distinguished by composition, size, shape, aspect ratio (L / D), etc. In some embodiments, the filler may have a low aspect ratio (e.g., less than about 1) or a high aspect ratio (e.g., chopped or crushed fibers).

[0136] The adhesive composition contains, based on the weight of the composition, about 1 to about 35% by weight of a preferably inorganic filler. In some embodiments, the adhesive composition contains, based on the weight of the composition, about 1% by weight, about 5% by weight, about 10% by weight, about 12% by weight, about 13% by weight, about 14% by weight, about 15% by weight, about 16% by weight, about 17% by weight, about 18% by weight, about 20% by weight, about 25% by weight, about 30% by weight, or about 35% by weight of a filler. In other embodiments, the adhesive composition is based on the weight of the composition and is approximately 1 to approximately 30% by weight, approximately 1 to approximately 25% by weight, approximately 1 to approximately 20% by weight, approximately 1 to approximately 15% by weight, approximately 1 to approximately 10% by weight, approximately 1 to approximately 5% by weight, approximately 5 to approximately 35% by weight, approximately 5 to approximately 30% by weight, approximately 5 to approximately 25% by weight, approximately 5 to approximately 20% by weight, approximately 5 to approximately 15% by weight, approximately 5 to approximately 10% by weight, approximately 10 to approximately 35% by weight, approximately 10 to approximately 30% by weight, approximately 10 to approximately 25% by weight, approximately 10 to approximately 20% by weight, approximately 10 to approximately 15% by weight, approximately 12 to approximately 35% by weight, approximately 12 to approximately 30% by weight, approximately 12 to approximately 25% by weight, approximately 12 to approximately 20% by weight, approximately 12 to approximately 18% by weight, and approximately 12 Contains approximately 16% by weight, approximately 12-14% by weight, approximately 14-35% by weight, approximately 14-30% by weight, approximately 14-25% by weight, approximately 14-20% by weight, approximately 14-18% by weight, approximately 14-16% by weight, approximately 16-35% by weight, approximately 16-30% by weight, approximately 16-25% by weight, approximately 16-18% by weight, approximately 18-35% by weight, approximately 18-30% by weight, approximately 18-25% by weight, approximately 18-20% by weight, approximately 20-35% by weight, approximately 20-30% by weight, approximately 20-25% by weight, approximately 25-35% by weight, approximately 25-30% by weight, or approximately 30-35% by weight of filler. In further embodiments, the adhesive composition contains about 12 to about 18% by weight of filler, based on the weight of the composition. In other embodiments, the adhesive composition contains about 4 to about 6% by weight of filler, based on the weight of the composition.

[0137] Examples of inorganic fillers include, but are not limited to, desiccants, thixotropes, or combinations thereof. In some embodiments, the inorganic filler may include, or may contain, calcium oxide, calcium metasilicate, mica, mixed mineral thixotropes, hydrophobic surface-treated fumed silica, hollow glass microspheres, or combinations thereof.

[0138] In some embodiments, the inorganic filler includes calcium oxide. The adhesive composition may contain about 1 to about 10% by weight of calcium oxide, based on the weight of the composition. In some embodiments, the adhesive composition contains about 1% by weight, about 2% by weight, about 3% by weight, about 4% by weight, about 5% by weight, about 6% by weight, about 7% by weight, about 8% by weight, about 9% by weight, or about 10% by weight of calcium oxide. In other embodiments, the adhesive composition contains about 1 to about 8% by weight, about 1 to about 6% by weight, about 1 to about 4% by weight, about 1 to about 2% by weight, about 2 to about 10% by weight, about 2 to about 8% by weight, about 2 to about 6% by weight, about 2 to about 4% by weight, about 4 to about 10% by weight, about 4 to about 8% by weight, about 4 to about 6% by weight, about 6 to about 10% by weight, or about 8 to about 10% by weight of calcium oxide, based on the weight of the composition. In a further embodiment, the adhesive composition contains about 4 to about 6% by weight of calcium oxide, based on the weight of the composition.

[0139] In other embodiments, the inorganic filler includes calcium metasilicate. Examples of calcium metasilicate include, but are not limited to, Nyad 400M. In one embodiment, the adhesive composition contains about 1 to about 10% by weight of calcium metasilicate, based on the weight of the composition. In other embodiments, the adhesive composition contains about 1% by weight, about 2% by weight, about 3% by weight, about 4% by weight, about 5% by weight, about 6% by weight, about 7% by weight, about 8% by weight, about 9% by weight, or about 10% by weight of calcium metasilicate, based on the weight of the composition. In other embodiments, the adhesive composition contains, based on the weight of the composition, about 1 to about 8% by weight, about 1 to about 6% by weight, about 1 to about 4% by weight, about 1 to about 2% by weight, about 2 to about 10% by weight, about 2 to about 8% by weight, about 2 to about 6% by weight, about 2 to about 4% by weight, about 4 to about 10% by weight, about 4 to about 8% by weight, about 4 to about 6% by weight, about 6 to about 10% by weight, about 6 to about 8% by weight, or about 8 to about 10% by weight of calcium metasilicate. In further embodiments, the adhesive composition contains, based on the weight of the composition, about 4 to about 6% by weight of calcium metasilicate.

[0140] In further embodiments, the inorganic filler includes mica. Examples of mica include, but are not limited to, WG325. In some embodiments, the adhesive composition contains, based on the weight of the composition, about 0.1% by weight, about 0.2% by weight, about 0.3% by weight, about 0.4% by weight, about 0.5% by weight, about 0.6% by weight, about 0.7% by weight, about 0.8% by weight, about 0.9% by weight, or about 1% by weight of mica. In other embodiments, the adhesive composition contains mica in amounts of about 0.1 to about 0.8% by weight, about 0.1 to about 0.6% by weight, about 0.1 to about 0.4% by weight, about 0.1 to about 0.2% by weight, about 0.2 to about 1% by weight, about 0.2 to about 0.8% by weight, about 0.2 to about 0.6% by weight, about 0.2 to about 0.4% by weight, about 0.2 to about 0.3% by weight, about 0.4 to about 1% by weight, about 0.4 to about 0.8% by weight, about 0.4 to about 0.6% by weight, about 0.6 to about 1% by weight, about 0.6 to about 0.8% by weight, or about 0.8 to about 1% by weight, based on the weight of the composition. In further embodiments, the adhesive composition contains mica in amounts of about 0.2 to about 0.3% by weight, based on the weight of the composition.

[0141] In yet another embodiment, the inorganic filler comprises a mixed mineral thixotrope. In some embodiments, the adhesive composition contains, based on the weight of the composition, about 0.1% by weight, about 0.2% by weight, about 0.3% by weight, about 0.4% by weight, about 0.5% by weight, about 0.6% by weight, about 0.7% by weight, about 0.8% by weight, about 0.9%, or about 1% by weight of the mixed mineral thixotrope. Examples of mixed mineral thixotropes include, but are not limited to, Garamite® products, which include Garamite® 7305 or Garamite® 1958. In other embodiments, the adhesive composition contains mixed mineral thixotropes in about 0.1 to about 0.8% by weight, about 0.1 to about 0.6% by weight, about 0.1 to about 0.4% by weight, about 0.1 to about 0.2% by weight, about 0.2 to about 1% by weight, about 0.2 to about 0.8% by weight, about 0.2 to about 0.6% by weight, about 0.2 to about 0.4% by weight, about 0.2 to about 0.3% by weight, about 0.4 to about 1% by weight, about 0.4 to about 0.8% by weight, about 0.4 to about 0.6% by weight, about 0.6 to about 1% by weight, about 0.6 to about 0.8% by weight, or about 0.8 to about 1% by weight. In further embodiments, the adhesive composition contains mixed mineral thixotropes in about 0.3 to about 0.6% by weight, based on the weight of the composition.

[0142] In further embodiments, the inorganic filler includes fumed silica such as hydrophobic surface-treated fumed silica. Examples of hydrophobic surface-treated fumed silica include, but are not limited to, those commercially available under the trademark name CAB-O-SIL or hydrophobic fumed silica such as polydimethylsiloxane (PDMS) treated fumed silica. In one embodiment, the adhesive composition contains about 1 to about 8% by weight of hydrophobic surface-treated fumed silica based on the weight of the composition. In other embodiments, the adhesive composition contains about 1% by weight, about 2% by weight, about 3% by weight, about 4% by weight, about 5% by weight, about 6% by weight, about 7% by weight, or about 8% by weight of hydrophobic surface-treated fumed silica based on the weight of the composition. In further embodiments, the adhesive composition contains, based on the weight of the composition, about 1 to about 8% by weight, about 1 to about 6% by weight, about 1 to about 4% by weight, about 1 to about 2% by weight, about 2 to about 10% by weight, about 2 to about 8% by weight, about 2 to about 6% by weight, about 2 to about 4% by weight, about 3 to about 9% by weight, about 3 to about 7% by weight, about 3 to about 5% by weight, about 4 to about 10% by weight, about 4 to about 8% by weight, about 4 to about 6% by weight, about 6 to about 10% by weight, about 6 to about 8% by weight, or about 8 to about 10% by weight of hydrophobic surface-treated fumed silica. In further embodiments, the adhesive composition contains, based on the weight of the composition, about 3 to about 4% by weight of hydrophobic surface-treated fumed silica. In yet another embodiment, the adhesive composition contains, based on the weight of the composition, about 4% by weight of hydrophobic surface-treated fumed silica. In a further embodiment, the adhesive composition contains approximately 3.4% by weight of hydrophobic surface-treated fumed silica, based on the weight of the composition.

[0143] In other embodiments, the inorganic filler includes glass microspheres such as hollow glass microspheres, which are commercially available and well known in the art. In one embodiment, the adhesive composition contains about 0.5 to about 3% by weight of hollow glass microspheres, based on the weight of the composition. In other embodiments, the composition contains about 0.5% by weight, about 0.6% by weight, about 0.7% by weight, about 0.8% by weight, about 0.9% by weight, about 1% by weight, about 1.5% by weight, about 2% by weight, about 2.5% by weight, or about 3% by weight of hollow glass microspheres, based on the weight of the composition. In a further embodiment, the adhesive composition is provided in an amount based on the weight of the composition of approximately 0.5 to approximately 2.5% by weight, approximately 0.5 to approximately 2% by weight, approximately 0.5 to approximately 1.5% by weight, approximately 0.5 to approximately 1% by weight, approximately 0.5 to approximately 0.8% by weight, approximately 0.5 to approximately 0.6% by weight, approximately 0.6 to approximately 3% by weight, approximately 0.6 to approximately 2.5% by weight, approximately 0.6 to approximately 2% by weight, approximately 0.6 to approximately 1.6% by weight, approximately 0.6 to approximately 1% by weight, approximately 0.6 to approximately 0.8% by weight, and approximately 0. The composition contains approximately 8 to 3% by weight, approximately 0.8 to 2.5% by weight, approximately 0.8 to 2% by weight, approximately 0.8 to 1.5% by weight, approximately 0.8 to 1% by weight, approximately 1 to 3% by weight, approximately 1 to 2.5% by weight, approximately 1 to 2% by weight, approximately 1 to 1.5% by weight, approximately 1.5 to 3% by weight, approximately 1.5 to 2.5% by weight, approximately 1.5 to 2% by weight, approximately 2 to 3% by weight, approximately 2 to 2.5% by weight, or approximately 2.5 to 3% by weight of hollow glass microspheres. In yet another embodiment, the adhesive composition contains approximately 0.6 to 1% by weight of hollow glass microspheres, based on the weight of the composition.

[0144] J. Any additional epoxy resin The adhesive compositions of this disclosure may contain one or more additional epoxy resins different from the epoxy resins described above as "A. Epoxy Resin". In some embodiments, the adhesive composition contains one or more "J. Additional Epoxy Resins". In other embodiments, the adhesive composition contains multiple additional epoxy resins, for example, in further embodiments, the adhesive composition may contain two, three, four, or more "J. Additional Epoxy Resins".

[0145] In some embodiments, the additional epoxy resin may be a phenol novolac epoxy. Such a polyfunctional epoxy resin may be prepared from a phenol novolac resin and epichlorohydrin. Upon curing, it forms a cured product having a mesh structure with a high crosslinking density. It also exhibits excellent heat resistance and chemical resistance. In the liquid epoxy adhesive compositions described herein, if a phenol novolac epoxy is present, its EEW is preferably in the range of about 165 to about 185, or about 172 to about 179. Suitable epoxy novolac resins include those sold under the trademark DEN®, such as the 300 and 400 series epoxy novolac resins commercially available from Olin.

[0146] K. Any other ingredients The adhesive composition may optionally contain additional components such as additives. Examples of additives include plasticizers such as tricresyl phosphate, diluents such as chemically inert hydrocarbon resins compatible with epoxy resins, fillers, colorants such as pigments (which also function as fillers) and dyes, coupling agents such as silane coupling agents such as γ-glycidoxypropyltrimethoxysilane coupling agents, leavening agents, foaming agents, flow modifiers, and antioxidants.

[0147] Method for manufacturing adhesive compositions Methods for producing adhesive compositions are described herein. In certain embodiments, the method involves mixing the corresponding components at a temperature below the activation energy of the final target composition. In certain embodiments, this temperature may be in the range of about 20°C to about 40°C, about 40°C to about 60°C, about 60°C to about 80°C, or any combination of two or more of the above ranges.

[0148] Generally, the simplest method is to pre-mix the components that exist as liquids at room temperature and then add the components that exist as solids at room temperature, although the mixing order is not considered important. In one embodiment, a curing agent package such as DICY, urea, and a latent reagent are added in the final stage.

[0149] Method of using adhesive composition The epoxy adhesive compositions described herein are useful in the transportation industry, such as in the manufacture of aircraft, automobiles, ships, and construction vehicles using thermosetting methods. In preferred embodiments, the epoxy adhesive compositions may be used on vehicle parts or components where impact resistance is required. For example, a method for forming structural adhesion may include forming adhesion between surfaces, and the adhesion may be subjected to shear force, peel force, and wedge impact, as measured by those skilled in the art using a lap shear strength test according to ASTM D1002; peel resistance, as measured using the T-type peel strength condition of ASTM D1876-08(2015)e1; and resistance to crack fracture, as measured using the wedge impact method and equivalent performance tests of ISO 11343.2019. The surfaces to be bonded may be metal surfaces, composite material parts, or combinations thereof. For example, in vehicle manufacturing, methods include bonding at metal-to-metal interfaces such as hem flanges, and bonding methods such as body panel bonding using welded joints, which are a combination of spot welding and adhesive bonding. The use of adhesive compositions to form a bonding surface including a corresponding cured epoxy adhesive layer is considered an independent embodiment of the present disclosure, as is the method of using them for this purpose.

[0150] The adhesive composition can be applied to the substrate by any convenient method. Preferably, the composition can be pumped and applied at room temperature, or, if necessary, heated to a temperature at which the latent curing agent does not activate. The adhesive can be applied manually and / or by robot, for example, using a jet spray method or an extruder. The composition can be extruded in bead form from a robot or applied by mechanical or manual application means, and can also be applied using a swirl application method or a streaming application method. In the swirl application method and the streaming application method, equipment known in the art, such as a pump, control system, measuring gun, remote measuring device, and application gun, is used. The adhesive composition may be applied to one or both of the substrates to be joined. After applying the adhesive composition, the substrates are brought into contact so that the adhesive is located at the joint line between the substrates. The substrates are brought into contact so that the adhesive is located between the substrates to be joined. Subsequently, the adhesive composition is heated to a temperature at which the thermosetting or latent curing agent begins to cure the epoxy resin composition, and the cured epoxy adhesive is placed between the substrates to form an adhesive assembly bonded to the substrates.

[0151] In some embodiments, the adhesive composition may be formulated to function as a hot melt. A hot melt is an adhesive that is solid at room temperature but, when heated to a temperature above room temperature, is converted into a pumpable or fluid material. In another embodiment, the composition of the present invention may be formulated to be pourable or pumpable at room temperature or slightly above, since in most applications it is preferable to heat the adhesive only to a temperature where the latent curing agent has not yet activated. The molten composition may be applied directly to the substrate surface or poured into a space separate from the substrates to be joined, such as in hem flange processing. In yet another embodiment, the composition is formulated (by containing fine thermoplastic resin or by using multiple curing agents with different activation temperatures) such that the curing process proceeds in two or more stages (partial curing at a first temperature and complete curing at a second, higher temperature). Two parts are joined, for example, immediately after the adhesive is deposited, thereby provisionally bonding the two parts to each other.

[0152] The resulting bond may already possess sufficient strength to prevent the still-uncured adhesive from being easily washed away. This can occur, for example, if metal plates bonded together are treated in a cleaning tank for degreasing and then in a phosphate treatment tank.

[0153] The adhesive composition may finally cure at a temperature significantly higher than the temperature at which the composition was applied to the parts to be bonded, and at a temperature above the temperature at which the curing agent and / or accelerator and / or latent swelling agent (if present) is activated (i.e., in the case of a curing agent, the lowest temperature at which the curing agent becomes reactive with the other components of the adhesive; in the case of a swelling agent, the lowest temperature at which the swelling agent causes foaming or expansion of the adhesive). Curing is carried out by heating the epoxy adhesive to a temperature of 135°C or higher. In some embodiments, the temperature is about 220°C or lower, for example, about 180°C or lower. In other embodiments, the temperature is about 140 to about 150°C. In further embodiments, the temperature is about 140°C. In yet another embodiment, the temperature is about 190°C. The time required for complete curing depends somewhat on the temperature, but is generally at least 5 minutes, more typically about 15 to about 120 minutes. In certain embodiments, the adhesive composition is heated at about 140°C for about 15 minutes. In other embodiments, the adhesive composition is further heated at about 190°C for about 60 minutes. Curing times exceeding 60, 90, or 120 minutes are generally not useful in most manufacturing applications, especially on assembly lines.

[0154] The adhesive composition can be used to bond various substrates, including metals, coated metals, aluminum, various plastics and filled plastic substrates, and glass fibers. The substrates to be joined using the adhesive may be the same or different. The adhesive may be used to bond metal parts, particularly steel sheets such as cold-rolled steel sheets. Electro-galvanized steel sheets, hot-dip galvanized steel sheets, boron steel sheets, and / or zinc / nickel plated steel sheets can also be used. The adhesive composition is also useful for bonding substrates whose surfaces are contaminated with oily substances, and good adhesion can be obtained even in the presence of such contamination.

[0155] Further applications of the adhesive composition include adhesives for fiber-reinforced composites using thermosetting methods in the transportation industry, such as aircraft, automobiles, ships, locomotives, and construction vehicles. The surfaces to be bonded may be metal surfaces, composite material parts, or combinations thereof. One application of the adhesive composition is the formation of structural bonds in vehicle structures such as hem flanges.

[0156] In other embodiments, the adhesive composition is used to bond parts (e.g., surfaces) of an automobile or other vehicle. Such parts may be steel, coated steel, galvanized steel, aluminum, coated aluminum, plastics, and filled plastic substrates. In some embodiments, the parts may be steel or aluminum. Particularly interesting applications include bonding vehicle frame parts to each other or to other parts of a vehicle. Frame parts are often metals such as cold-rolled steel, galvanized metal, or aluminum. Parts bonded to frame parts may also be metals as described above, but may be other metals, plastics, composite materials, etc. Assembled automobile frame members are usually coated with a coating material (e.g., paint) that requires firing and curing. The coating is usually fired at a temperature of about 140°C to about 190°C. In such cases, it is convenient to apply the epoxy adhesive to the frame parts, then apply the coating, and cure the epoxy adhesive simultaneously with the firing and curing of the coating. In some embodiments, curing may not occur immediately after application of the epoxy adhesive. During such a delay period before curing, the epoxy adhesive may be exposed to moist air up to about 40°C.

[0157] Adhesive assembly including a curing adhesive layer The products disclosed herein include a cured adhesive layer prepared by thermal curing a liquid epoxy adhesive composition described herein on a substrate, and preferably bond two or more substrates to form an adhesive assembly. In a preferred embodiment, the nominal thickness of the cured adhesive layer is about 0.25 to about 0.5 mm, for example, about 0.3 to 0.4 mm.

[0158] The cured adhesive layer is bonded to substrates including cold-rolled steel (CRS), electro-galvanized steel (EZG), hot-dip galvanized steel (HDG), or treated aluminum. The cured adhesive layer exhibits excellent adhesion to these substrates. In some embodiments, the cured epoxy adhesive layer exhibits a 100% cohesive failure mode in delamination when tested on cold-rolled steel (CRS), electro-galvanized steel (EZG), hot-dip galvanized steel (HDG), and / or treated aluminum under the T-type delamination conditions of ASTM D1876-08(2015)e1 or the wedge impact method of ISO 11343.2019. These results are achievable without relying on high concentrations of fillers to achieve a 100% cohesive failure mode.

[0159] The adhesive compositions described herein exhibit high T-type peel strength even after exposure to high-temperature humid conditions in an uncured state. Furthermore, under low-temperature and high-temperature firing curing conditions, they exhibit good impact resistance even at low temperatures of -30°C and even -40°C. As shown in the examples, the cured epoxy adhesive layer is: (a) By curing two 0.8 mm thick cold-rolled steel sheets at approximately 140°C for approximately 15 minutes, sufficient adhesive strength between the sheets is obtained to exhibit a T-type peel strength of at least approximately 4, approximately 5, approximately 6, approximately 7, approximately 8, approximately 9, approximately 10, approximately 11, approximately 12, approximately 13, approximately 14, or approximately 15 N / mm at room temperature; and / or, (b) By curing two 0.8 mm thick cold-rolled steel sheets at approximately 190°C for approximately 60 minutes, sufficient adhesive strength between the sheets is obtained to exhibit a T-type peel strength of at least approximately 9, approximately 10, approximately 11, approximately 12, approximately 13, approximately 14, or approximately 15 N / mm at room temperature; and / or, (c) By curing two 1.3 mm thick cold-rolled steel sheets at approximately 140°C for approximately 15 minutes, sufficient adhesive strength between the sheets is obtained to exhibit a lap shear strength of at least approximately 10, approximately 15, approximately 20, approximately 25, approximately 30, approximately 31, approximately 32, or approximately 35 N / mm at room temperature; and / or, (d) By curing two 1.3 mm thick cold-rolled steel sheets at approximately 190°C for approximately 60 minutes, sufficient adhesive strength between the sheets is obtained to exhibit a T-type peel strength of at least approximately 30, approximately 31, approximately 32, approximately 33, approximately 34, or approximately 35 N / mm at room temperature; and / or, (e) By curing two 0.8 mm thick cold-rolled steel sheets at approximately 140°C for approximately 15 minutes, sufficient adhesive strength between the sheets is obtained to exhibit an impact wedge peel strength of at least approximately 30, approximately 31, approximately 32, approximately 33, approximately 34, approximately 35, approximately 36, approximately 37, approximately 38, approximately 39, or approximately 40 N / mm at room temperature; and / or, (f) By curing two 0.8 mm thick cold-rolled steel sheets at approximately 190°C for approximately 60 minutes, sufficient adhesive strength between the sheets is obtained to exhibit an impact wedge peel strength of at least approximately 10, approximately 15, approximately 20, approximately 25, or approximately 30 N / mm at room temperature; and / or, (g) By curing two 0.8 mm thick cold-rolled steel sheets at approximately 140°C for approximately 15 minutes, sufficient adhesive strength between the sheets is obtained to exhibit an impact wedge peel strength of at least approximately 9, approximately 10, approximately 11, approximately 12, approximately 13, approximately 14, or approximately 15 N / mm at approximately -40°C; and / or, (h) By curing two 0.8 mm thick cold-rolled steel plates at approximately 190°C for approximately 60 minutes, sufficient adhesive strength between the plates is obtained to exhibit an impact wedge peel strength of at least approximately 15, approximately 20, approximately 25, or approximately 30 N / mm at approximately -40°C.

[0160] This disclosure encompasses all products comprising any of the epoxy adhesive compositions in a coated (but not fully cured) liquid state (pre-cured or partially cured) and any of the cured epoxy adhesive layers bonded thereto. In certain embodiments, the products may be used in the transportation industry, such as in aircraft, automobiles, ships, and construction vehicles, using thermosetting methods. In preferred embodiments, the epoxy adhesive compositions may be used in vehicle parts or components where impact resistance is desired. For example, a method for forming a structural bond may involve forming a bond between surfaces that may be subjected to shear forces, peel forces, and wedge impacts. The surfaces to be bonded may be metal surfaces, composite material components, or combinations thereof, and are useful, for example, in automobiles or their components.

[0161] Terms and Abbreviations In this disclosure, the singular forms "a," "an," and "the" also include the plural forms, and references to specific numerical values ​​include at least that specific value unless the context explicitly indicates otherwise. Therefore, for example, a reference to "corrosion inhibitor" refers to one or more corrosion inhibitors and their equivalents known to those skilled in the art. Furthermore, where an element is indicated as "may be" X, Y, or Z, such usage is not intended to exclude other options for that element in all cases.

[0162] When a value is expressed as an approximation using the phrase "approximately," it is understood that the particular value constitutes a different embodiment. Generally, the use of the term "approximately" indicates an approximation that may vary depending on the desired characteristics to be obtained by the subject matter of this disclosure, and should be interpreted on a functional basis in the specific context in which the term is used. Those skilled in the art will be able to interpret this routinely. Where applicable, all ranges are inclusive and combinable; that is, a reference to a value indicated in a range encompasses all values ​​within that range.

[0163] In this specification, it should be understood that certain features of the Disclosure described in the context of individual embodiments for clarity may also be provided in combination in a single embodiment. That is, unless they are obviously incompatible or explicitly excluded, each individual embodiment is considered combinatorial with other embodiments, and such combination constitutes a different embodiment. Conversely, various features of the Disclosure described in the context of a single embodiment for brevity may be provided separately or in any subcombination. Finally, while embodiments may be described as part of a series of steps or as part of a more general structure, each step is considered an independent embodiment and can be combined with other steps.

[0164] The transitional terms “contains,” “essentially consists of,” and “consist of” are intended to imply meanings commonly accepted in patent terminology. In embodiments provided using the term “essentially consists of,” the basic and novel features are the ease of operation of a method or composition / system for providing a composition exhibiting claimed functional features using only the described components.

[0165] When a value is expressed as an approximation using the preposition "approximately," it is understood that the particular value may form another embodiment. In general, the use of the term "approximately" indicates an approximation that may vary depending on the desired properties to be obtained by the subject matter of this disclosure and should be interpreted in the specific context in which it is used, based on its function. In some embodiments, "approximately X" (where X is a number) refers to ±10% (inclusive) of the stated value. For example, the phrase "approximately 8" may refer to values ​​(inclusive) from 7.2 to 8.8. This value may also include "exactly 8." If present, all ranges include both ends and are combinable. For example, if the range "1 to 5" is stated, the stated range should be interpreted as optionally including ranges such as "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," etc. Furthermore, if a list of options is explicitly provided, such a list may include embodiments in which any of the options may be excluded. For example, if a range "1-5" is specified, such a specification can support situations where 1, 2, 3, 4, or 5 is excluded. Therefore, the specification "1-5" can support "1 and 3-5, but not 2," or simply "does not include 2."

[0166] For various reasons, it is preferable that the inventions disclosed herein (e.g., compositions, uncured adhesives, pre-cured adhesives and cured adhesives, methods, and products) can be manufactured without certain components, i.e., with the exception of trace amounts of contaminants, certain materials are absent whether added or generated in situ, or many components used in the prior art as components for similar purposes are absent or substantially absent. Specifically, independently of each of the preferably minimized components described below, at least some embodiments of the present invention contain the following components: oxidizing agents such as copper, imidazole, peracids, permanganates, perchlorates, chlorates, chlorites, chlorites, hypochlorites, perborates, hexavalent chromium, trivalent chromium, sulfuric acid and sulfates, nitric acid and nitrate ions; as well as fluorine, formaldehyde, formamide, hydroxylamine, cyanide, cyanate, rare earth metals; boron, e.g., borax, borate; strontium; free halogen ions, e.g., fluoride, chloride, bromide or iodine The epoxy curing accelerator, comprising a compound; and / or an unsubstituted urea, imidazole, dihydroxybenzene, adipic anhydride, phosphonium ionic liquid, unblocked tertiary amine or ambiently active blocked tertiary amine, polyamine salt of a polyhydric phenol, or a combination thereof, is preferably contained in an amount of 1.0, 0.5, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002% or less, more preferably the values ​​being in grams per liter, and more preferably the values ​​being in ppm per liter, in the order listed.

[0167] In this specification, "diglycidyl ether of bisphenol A" or "DGEBA" refers to 2,2-bis(4-glycidyloxyphenyl)propane, which is an epoxy resin commercially available under the trademark names Epon828, DER331, and Kukdo YD-128. In this specification, "diglycidyl ether of bisphenol F" and "DGEBF" refer to bis(4-glycidyloxyphenyl)methane, which is an epoxy resin commercially available under the trademark names Epon862 and DER354s.

[0168] Unless otherwise specified, composition percentages are expressed as weight percentages relative to the weight of the material or composition.

[0169] [Table 1]

[0170] The present invention will be described in more detail in the following embodiments. These embodiments illustrate preferred embodiments of the present invention and are for illustrative purposes only; they should not be construed as limiting the scope of the appended claims. From the above discussion and these embodiments, those skilled in the art will be able to grasp the essential features of the present invention and make various changes and modifications to the invention to suit various uses and conditions without departing from the spirit and scope of the invention. [Examples]

[0171] As those skilled in the art will understand, the present invention is subject to numerous modifications and changes in light of these teachings, all of which are incorporated herein by reference. The entirety of each patent, patent application, and publication disclosed herein is incorporated herein by reference.

[0172] Examples 1-4: DICY + single accelerator Increasing the concentration of the modified urea accelerator lowers the curing reaction initiation temperature, thus increasing the reactivity under low-temperature isothermal conditions compared to when the concentration of the modified urea accelerator is low. In these examples, the effects of increasing the concentration of the reinforcing agent and modified urea accelerator on the structural adhesive properties were investigated for the formulations of a control structural adhesive (Comparative Example 1) and experimental adhesives (Comparative Examples 2-4) using adhesive curing periods of 140°C for 15 minutes and 190°C for 60 minutes. For each example, three or more test pieces were divided into two sets for testing. The first set was cured under 140°C conditions (low-temperature firing, "LB"), and the second set was cured under 190°C conditions (high-temperature firing, "HB"). Adhesion tests and impact tests were performed on the cured sets. The results shown below are the average performance values ​​for each set.

[0173] The formulations in Table 1 were prepared by a method of forming a homogeneous mass by blending and mixing the listed components. First, the organic components other than the curing agent were blended and mixed under vacuum (8.5 kPa) until completely dissolved and / or uniformly dispersed. Then, the inorganic filler was added under vacuum, and the mixture was homogenized under vacuum until no gas was trapped inside. After that, the mixture was cooled to room temperature, and the curing agent was mixed into the mixture to prepare a 1K epoxy structural adhesive. Unless otherwise specified herein, all adhesive formulations in the examples were prepared according to this method.

[0174] [Table 2]

[0175] The reinforcing agents PU1 and PU2 both share the characteristic of having a polytetramethylene glycol (PTMEG) backbone. According to the manufacturer, PU1 is a bisphenol-terminated polyurethane prepolymer with a MW of approximately 10-20 K daltons. PU2 is a polyurethane prepolymer asymmetrically end-capped with oxime and hydrophobic monophenol functional groups, with a MW of approximately 10,000 daltons. PU2 exhibited a significantly lower deblocking temperature than PU1, and at least one end capping was more hydrophobic than the bisphenol end capping of PU1.

[0176] The curing reaction initiation temperature and conversion rate of each adhesive in Comparative Examples 1 to 4 were measured using differential scanning calorimetry (DSC). First, 12 ± 1 mg of adhesive was placed in a T-zero® sealed dish, sealed, and then the DSC was set to Q100, and the temperature was increased from 0°C to 300°C at a rate of 10°C / min. The reaction initiation temperature and reaction enthalpy were measured using this linear temperature gradient. Second, a new sample was prepared using the same dish and a second dose of adhesive, and after increasing the temperature from 23°C to 140°C for 7 minutes, the progress of the reaction at 140°C was measured as a function of time. This was done to simulate the oven curing conditions at the new lower curing limit.

[0177] Unless otherwise specified herein, throughout the examples, the DSC results for exemplary adhesives were obtained using the procedure described above.

[0178] [Table 3]

[0179] In the isothermal DSC experiments, the time to reach the exothermic reaction peak and the heat of reaction were measured using the instrument's software. Finally, the time function of the degree of hardening was plotted from the isothermal DSC results. Figure 1 shows the time functions of the degree of hardening for Comparative Examples 1 to 4.

[0180] The results in Table 2 show that as the concentration of 1,1-dimethylurea increases, the reaction initiation temperature (linear ramp) decreases and the time to reach the exothermic peak (isothermal holding) shortens under isothermal conditions at 140°C. Furthermore, under isothermal conditions, the reaction enthalpy increases as the concentration of 1,1-dimethylurea increases, indicating an increase in the degree of reactivity at 140°C. The sigmoid curve in Figure 1 shows that the degree of hardening as a function of time increases with increasing concentration of modified urea. Interestingly, the linear ramp shows that the total enthalpy of the reaction decreases with increasing concentration of 1,1-dimethylurea.

[0181] The adhesive and impact properties of Comparative Examples 1-4 were measured by lap shear strength using the LSS test in accordance with ASTM D1002. Peel resistance was measured in N / mm using the T-type peel strength condition of ASTM D1876-08(2015)e1, and crack fracture resistance was measured in N / mm using the wedge impact method of ISO 11343.2019. The results are shown in Table 3A. "LB" indicates low-temperature firing, and "HB" indicates high-temperature firing. Unless otherwise specified in this specification, adhesives were tested using these tests throughout this specification.

[0182] [Table 4]

[0183] These results indicate that at the lower limit of the new "extended curing region," which is 140°C for 15 minutes at a "metal temperature" (approximately 7 minutes in a standard oven), Comparative Examples 1 and 2 did not fully cure and failed to exhibit good adhesion and impact properties. However, in Comparative Examples 3 and 4, increasing the concentration of 1,1-dimethylurea to over 1% by weight and 2% by weight, respectively, improved the T-type peel strength and lap shear strength after curing at 140°C for 15 minutes. Furthermore, in Comparative Example 4, incorporating 1,1-dimethylurea at a concentration exceeding 2% by weight resulted in a low-temperature impact wedge peel strength exceeding 10 N / mm (test temperature -40°C) after curing at 140°C for 15 minutes. Similarly, examining the data in Figure 1, it can be seen that after curing at 140°C for 15 minutes, Comparative Example 4 showed a conversion rate of over 90%, while Comparative Example 3 showed a conversion rate slightly below 80%. Therefore, in order to obtain good impact wedge peeling properties (low temperature) after curing at 140°C for 15 minutes, it is desirable that the 1,1-dimethylurea content exceeds 2% by weight.

[0184] Interestingly, an inverse correlation was observed between the concentration of 1,1-dimethylurea and the IWP intensity at low temperatures (-40°C) after firing curing conditions at low temperatures (LB) and high temperatures (HB), respectively. Specifically, the IWP intensity at LB-40°C increased with increasing 1,1-dimethylurea concentration, while the IWP intensity at HB-40°C decreased with increasing 1,1-dimethylurea concentration. This finding is significant because automotive OEMs require crash durability at both the upper and lower limits of the curing process range, even though they want to lower the lower limit of curing requirements. Therefore, simply shifting the existing process curing range to include LB and excluding HB as described above may not be sufficient to meet the needs of automotive OEMs, and it may be desirable to balance the performance of LB and HB in different test scenarios.

[0185] To gain a deeper understanding of this phenomenon, dynamic mechanical analysis (DMA) was performed using TA Q800DMA and a dual cantilever fixture. The DMA data in Figure 2, and the corresponding Tg and storage modulus at 40°C and 180°C for Comparative Examples 2 and 4 shown in Table 3B, indicate that the accelerator concentration significantly affects thermosetting resin network formation and structure.

[0186] [Table 5]

[0187] At the 1,1-dimethylurea concentration required to obtain good LB-40°C IWP strength, an adhesive was obtained in which the Tg decreased by 16.8°C after curing under high-temperature firing conditions. This may be due to a significant increase in the molecular weight (Mc) between crosslinking bonds. The E' value at the rubbery plateau (180°C) decreased by 42.4%, indicating a significant decrease in crosslinking density. Therefore, the network properties achieved by the comparative adhesive composition are necessary to obtain good low-temperature (-40°C) impact wedge peeling properties across extended low-temperature and high-temperature firing curing conditions, and could not be achieved simply by increasing the concentration of the modified urea accelerator.

[0188] Screening of latent growth enhancer additives To address the challenge of achieving sufficient adhesive performance under both low-temperature curing conditions of 140°C for 15 minutes and high-temperature curing conditions of 190°C for 60 minutes, the applicant tested various latent accelerator additives through extensive research spanning more than one year. Each curing accelerator or combination thereof was incorporated into the same base formulation containing epoxy and DICY (and possibly modified urea), and then its performance was evaluated in much the same manner as described in Example 1. Unless otherwise specified, the amount of additive was selected based on available literature and manufacturer publications. The tests included lap shear strength (ASTM D1002), impact wedge peel strength (ISO 11343), reactivity by differential scanning calorimetry (DSC), and storage stability by parallel plate rheology testing. Table 4 shows the performance of adhesive formulations containing the listed latent accelerator additives, cured at 140°C for 15 minutes or 190°C for 60 minutes, respectively.

[0189] [Table 6]

[0190] [Table 7]

[0191] [Table 8]

[0192] Each latent accelerator additive, when used in the amounts / combinations shown in Table 4, had drawbacks in one or more aspects of low-temperature curing (LB) reactivity, storage stability, and good adhesive performance as a structural adhesive (i.e., lap shear strength, impact wedge peel strength, and T-type peel resistance). Epoxyamine adducts met some of the adhesive failure test criteria, but not all of them. The results indicate the need to improve the accelerator package containing DICY to produce a highly storage-stable 1K structural adhesive that passes structural adhesive performance tests after curing in the low-temperature range (140°C for 15 minutes) and maintains good adhesive performance after curing in the high-temperature range (190°C for 60 minutes).

[0193] Comparative Example 5 and Example 6 The applicant tested 2,4,6-tris-(dimethylaminomethyl)phenol, a tertiary amine based on a phenolic accelerator, in adhesive formulations prepared as described in Example 1. The tertiary amine accelerator exhibited excellent adhesion and "full-spectrum" impact properties across the extended curing regions of LB and HB. However, without the accelerator being latent, i.e., without blocking agents or encapsulating agents, the adhesive formulation cured completely at room temperature and lacked sufficient storage stability for use as a 1K structural adhesive (even at low concentrations). The applicant considered modifications to the phenolic accelerator-based tertiary amine to be thermally activated, yet sufficiently stable at room temperature for use in 1K adhesives, and to promote DICY curing of epoxy resins in the desired curing regions of LB and HB. Adhesive compositions containing the components listed in Table 5 were prepared according to the method of Example 1. The properties of two adhesive formulations were compared, for example, the curing behavior, storage stability, adhesion, and impact properties of adhesive formulations using different blocked tertiary amine latent reagents based on phenol (e.g., tertiary aminophenol): A* - Tertiary aminophenol blocked with novolac resin according to U.S. Patent No. 9,000,120; and B* - Described by the manufacturer Ancamin® 2920 (Evonik) as a 1K encapsulation accelerator containing 25-50% by weight of a tertiary amine, 25-50% by weight of a polyhydroxyphenylalkyl polymer, and 25-50% by weight of an acrylic polymer, used to accelerate the DICY curing of epoxy resins.

[0194] [Table 9]

[0195] The curing reaction initiation temperature and conversion rate of the adhesives in Comparative Example 5 and Example 6 were measured using DSC. The DSC results in Table 6 and the storage stability results in Table 7 indicate that the blocking agent affects both the reactivity and storage stability of the adhesive composition. The epoxy adhesive in Example 6 showed improved reactivity and storage stability compared to Comparative Example 5. This result was surprising, considering that generally, increased reactivity of 1K thermosetting structural epoxy adhesives leads to decreased storage stability.

[0196] Figure 3 shows isothermal conversion curves comparing a 1K thermosetting structural epoxy adhesive with various accelerators, indicating that blocking agent A ("Comparative Example 5" without urea) promoted reactivity at 140°C to the same extent as alkyl-modified urea ("Comparative Example 2") used at a standard concentration (<1% by weight). The adhesive of Example 6 showed a more rapid increase in reaction rate in a shorter time under isothermal conditions at the lower limit of the extended curing region.

[0197] [Table 10]

[0198] Storage stability is a critical concern when producing useful 1K adhesives that can be cured in the curing range of 140°C for 15 minutes and 190°C for 60 minutes. 1K adhesives can become unusable due to a significant increase in viscosity over time. As shown in Table 7, while Comparative Examples 2-4 had low viscosity over time, their time to reach the exothermic peak was 11.7-23.2 minutes, significantly longer than the 8.8 minutes for the adhesive in Example 6. The viscosity increase over time for Comparative Example 5 was greater than that of the adhesive in Example 6, despite its longer time to reach the exothermic peak. These performance criteria demonstrate the difficulty of achieving sufficient storage stability while obtaining the desired reactivity at low temperatures.

[0199] [Table 11]

[0200] Furthermore, the results of the overlap shear test shown in Table 8 indicate that the cured adhesive of Example 6 exhibited higher overlap shear strength after LB curing than the cured adhesive of Comparative Example 5. This may be related to the degree of conversion (see Figure 3) and the difference in crosslink density resulting from low-temperature firing curing conditions.

[0201] [Table 12]

[0202] Examples 7 and 8 In the next series of adhesives produced, the polyurethane prepolymer (PU1) was kept constant, the amount of tertiary amine containing blocking agent B was varied, and the amount of urea was eliminated. Tests showed that incorporating this polyurethane prepolymer in combination with a specific curing agent composition improved T-type peel adhesion and impact wedge peel properties compared to PU2 (see Examples 9 and 10 below). While not bound by a single theory, the improvements in T-type peel and impact wedge peel are thought to be at least in part due to the decrease in crosslink density, improved interfacial fracture toughness, and resulting adhesion caused by the increase in MW of the soft segment of the PU1 prepolymer. The difference in deblocking temperatures between PU1 and PU2 also affects the reactivity and adhesive properties of the PU prepolymer.

[0203] [Table 13]

[0204] The starting temperature and conversion rate of the curing reaction in Examples 7 and 8 were measured using DSC. The DSC data in Table 10 shows that the reaction starting temperature (heating) and the time to the peak reaction (isotherm) were different in Examples 7 and 8.

[0205] [Table 14]

[0206] The storage stability of the epoxy adhesives in Examples 7 and 8 was tested. Table 11 below shows that the storage stability is comparable to that of modified urea, which is currently used in 1K impact-resistant adhesives.

[0207] [Table 15]

[0208] Table 12 shows the adhesive and impact properties of the epoxy adhesives of Examples 7 and 8. The cured epoxy adhesives of Examples 7 and 8, even with latent tertiary amine accelerators at concentrations exceeding 2% by weight based on phenol (containing 25-50% by weight of tertiary amine, 25-50% by weight of polyhydroxyphenylalkyl polymer, and 25-50% by weight of acrylic polymer), exhibited only moderate overlap shear strength, especially under low-temperature conditions, and also showed poor T-type peel adhesion and impact wedge peel properties. However, the epoxy adhesives of Examples 7 and 8 showed good impact wedge peel properties during HB curing, comparable to those of epoxy adhesives accelerated with modified urea (see Comparative Examples 2-4).

[0209] Furthermore, the relationship between conversion rate and time shown in Figure 4 can explain the low LB curing fracture characteristics. According to the data, the curing rates of Examples 7 and 8 after heating at 140°C for 15 minutes were 71.4% and 80.2%, respectively. Therefore, in order to achieve the desired adhesive fracture and adhesion characteristics after curing at 140°C for 15 minutes, the concentration of this accelerator had to be increased excessively, resulting in accelerated viscosity increase under accelerated heating aging conditions.

[0210] [Table 16]

[0211] DMA was used to evaluate the thermosetting network and impact properties of the epoxy adhesives shown in Figures 7 and 8 after HB curing. Since the curing of epoxy resins with DICY and accelerators is autocatalytic, increasing the heating rate until the HB curing temperature of 190°C is reached in equivalent time (7 minutes) results in a rapid conversion of available epoxy groups. Therefore, changes in the chemical properties of the accelerator reduce the difference in reaction rates, and as a result, the large differences in adhesive and impact properties are thought to be due not only to the curing rate but also to changes in network formation.

[0212] The DMA data for Comparative Examples 2 and 4 in Figure 5, and for Example 8, along with the corresponding Tg and E' values ​​at 40°C and 180°C in Table 13, demonstrate that the type and concentration of the accelerator affect the crosslinking density of the adhesive and the resulting Tg.

[0213] When the 1,1-dimethylurea concentration in the epoxy adhesive was increased, the reaction initiation temperature was lowered, and the curing reaction rate was increased (Comparative Example 2 vs. Comparative Example 4), the Tg after HB curing conditions decreased by 16.8°C. The decrease in Tg after HB (e.g., over-curing) curing of the epoxy adhesive in Comparative Example 4 corresponded to a 42.2% decrease in the storage modulus (E') at the rubbery plateau (measured at 180°C). Thus, increasing the modified urea concentration resulted in a significant decrease in network crosslink density under over-curing conditions. In comparison, Example 8, which did not contain urea, had a slightly higher Tg than Comparative Example 2, and the E' value at 180°C in the rubbery plateau also increased accordingly. The significant decrease in Tg and crosslink density after HB curing conditions correlated with a deterioration in the low-temperature impact wedge peeling properties of the cured epoxy adhesive. On the other hand, in the control composition (Comparative Example 2), acceleration of the reaction rate and maintenance or increase in the degree of crosslinking were observed, and good impact wedge peeling properties were obtained.

[0214] [Table 17]

[0215] These results suggest that specific combinations of 1,1-dimethylurea and phenol accelerator-based blocked tertiary amines may significantly improve reaction rates under new lower limit requirements (15 minutes at 140°C) while maintaining favorable controlled network characteristics (Comparative Example 2).

[0216] Examples 9-11 In the following series of epoxy adhesives, we investigated combinations of 1,1-dimethylurea and phenolic accelerator-based blocked tertiary amines to improve reaction rates under new lower limit requirements (140°C for 15 minutes) while facilitating control of network properties. Adhesive compositions containing the components listed in Table 14 were prepared according to the method of Example 1.

[0217] [Table 18]

[0218] The curing reaction initiation temperature and conversion rate for Examples 9-11 were measured using DSC. The DSC results in Table 15 show that the initiation temperature was similar to that of Example 7 when 1,1-dimethylurea and phenolic tertiary amine were used at concentrations of less than 1% by weight and less than 2% by weight, respectively. A comparison of the DSC data for Example 11 with that of Comparative Example 5 (without urea) showed a synergistic effect between 1,1-dimethylurea and the phenolic tertiary amine accelerator. The two accelerators synergistically promoted the reaction, and by keeping the concentrations of each accelerator type low (blocked tertiary amine phenol < 3% by weight, 1,1-dimethylurea < 1% by weight), the balance of storage stability, curing rate, network characteristics, and impact wedge peel characteristics necessary for adhesion was improved, and the performance requirements were met.

[0219] [Table 19]

[0220] The results of the storage stability of the epoxy adhesives of Examples 9 to 11 are shown in Table 16. The comparison of the viscosity changes between Example 9 (PU2) and Example 10 (PU1) shows the influence of the PU prepolymer on the viscosity stability. The comparison of the viscosity changes between Example 10 and Example 11 shows that the epoxy adhesive of Example 10 exhibited better viscosity stability than that of Example 11.

[0221]

Table 20

[0222] Also, when incorporated into an epoxy adhesive using a combination of 1,1-dimethylurea and a phenolic-blocked tertiary amine, the PU prepolymer was found to play an important role in the T-peel adhesion properties and impact wedge peel properties of the cured adhesive. Table 17 shows the results of the performance tests after curing of the epoxy adhesives of Examples 9 to 11 containing the PU prepolymer. Example 9 was inferior to Example 10 in terms of the T-peel adhesion properties at the lower cure limit (140 °C for 15 minutes) and the low-temperature impact properties at both extremes of the expanded cure region conditions (LB and HB).

[0223]

Table 21

[0224] This difference in performance is not due to the low conversion rate during LB curing. In the DSC experiment, the reaction start temperatures of Example 9 and Example 10 were the same. Furthermore, the conversion rate curves against time in Fig. 6 show that the same conversion rate occurred in Example 9 and Example 10 after curing at 140 °C for 15 minutes. Finally, after HB curing, it was also observed that the adhesive containing PU2 had inferior low-temperature impact properties compared to the adhesive containing PU1.

[0225] Examples 12 and 13 Adhesive compositions containing the components listed in Table 18 were prepared according to the method of Example 1. PU1 and PU2 were directly compared in adhesive compositions that did not contain other reinforcing agents such as CTBN and CSR, and differences in performance relative to the properties of the extended curing structural adhesive compositions, related to the PU prepolymer, were identified.

[0226] [Table 22]

[0227] Table 19 shows the performance test data for the cured epoxy adhesives of Example 12 and Example 13. In Example 13, compared to Example 12, which was formulated with a curing agent system containing both 1,1-dimethylurea and a phenolic blocked tertiary amine, the results of T-type peel adhesion and impact wedge peeling were significantly improved over the extended curing range conditions (140°C for 15 minutes and 190°C for 60 minutes).

[0228] [Table 23]

[0229] Example 14 We investigated methods to improve storage stability while maintaining adhesive failure properties after curing. Examples 10 and 14 directly compared two different CSR compositions available from Kaneka Corporation.

[0230] [Table 24]

[0231] The storage stability of the epoxy adhesives in Examples 10 and 14 was tested (see Table 21 below). Surprisingly, it was found that changing the CSR composition significantly improved storage stability while maintaining post-curing adhesion and impact wedge release properties under the target expanded curing region conditions (140°C for 15 minutes and 190°C for 60 minutes, respectively).

[0232] [Table 25]

[0233] The storage stability results in Table 21 indicate that in Example 14, the "initial" viscosity (viscosity of the adhesive immediately after formulation) decreased compared to Example 10. Even under accelerated heat aging conditions, Example 14 showed a lower viscosity than Example 10 and also had a lower viscosity increase rate after aging. The improvement in viscosity stability may be due to a decrease in the relative proportion of functional groups on the surface of the CSR particles. This improvement in storage stability is desirable because it is preferred that the viscosity of the adhesive composition be maintained below 5,000 Pa·s at 15°C and a shear rate of 3 s -1 and a value below 4,000 Pa·s at 15°C and a shear rate of 3 s -1 is preferred, which is advantageous.

[0234] The T-peel adhesion properties and impact chisel peel properties of the epoxy adhesive of Example 14 shown in Table 22 indicate that even when the Kaneka MX-154 CSR particles are directly replaced with Kaneka MX-EXP-EH2 (Kaneka MX-160) CSR particles, there is no adverse effect on the initial adhesion properties and impact peel properties. For direct comparison, refer to the T-peel adhesion properties and the performance of the impact chisel peel test of Example 10 in Table 17.

[0235]

Table 26

[0236] Examples 15 - 18 An adhesive composition containing the components described in Table 23 was manufactured according to the method of Example 1.

[0237]

Table 27

[0238] The performance test data of the cured epoxy adhesives of Examples 15 - 18 are shown in Table 24, and it was shown that the impact chisel peel properties at low temperature (-40°C) were significantly improved compared to the performance of Example 10 in Table 17.

[0239] [Table 28]

[0240] A different series of adhesive compositions containing the components described in Example 18 of Table 23 were prepared according to the method of Example 1, with the following modifications: the tertiary amine containing blocking B was omitted, and instead, various amounts of latent reactants described by the manufacturer as amine epoxy adducts were used (Examples 19, 20, and 21, 2.0% by weight, 2.5% by weight, and 3.5% by weight, respectively). The starting temperatures measured by DSC were 145°C, 140°C, and 132°C, respectively, and showed good low-temperature reactivity within the desired firing range. The adhesives of Examples 19–21 were aged at 35°C for 14 days and stability tests were performed for rheological increase (see Table 21). The viscosity increase of Examples 19–21 was in the range of 34%–50%, which was comparable to the stability obtained with other latent reactants in equivalent adhesive formulations according to the present invention (see Tables 7, 11, 16, and 21). Impact wedge peel tests were conducted at 23°C according to ISO 11343.2019 for adhesives cured by firing at 140°C for 15 minutes in examples 19-21, and the impact resistance was in the range of 15-20 N / mm. This suggests potential usefulness as a structural adhesive for hem flanges, epoxy adhesive tape, and a scalable epoxy structural adhesive useful in vehicle manufacturing.

[0241] Those skilled in the art will understand that the above embodiments are merely illustrative examples illustrating the components and performance of the present invention. These embodiments are not intended to limit the present invention to illustrative embodiments.

Claims

1. A structural adhesive composition useful for vehicle manufacturing, (i) Epoxy resins containing diglycidyl ethers of substituted or unsubstituted bisphenols; (ii) Latent reagents; (iii) Modified urea accelerator; (iv) dicyandiamide; (v) at least one reinforcing agent; (vi) at least one filler, and (vii) Optionally, an epoxy resin different from (i). An adhesive composition containing, essentially consisting of, or comprising these elements.

2. The adhesive composition according to claim 1, wherein the epoxy resin (i) has an epoxy equivalent weight (EEW) of about 150 to about 225.

3. The adhesive composition according to claim 2, wherein the epoxy resin (i) has about 170 to about 200 EEW.

4. The adhesive composition according to claim 2, wherein the epoxy resin (i) has about 185 to about 192 EEW.

5. The adhesive composition according to claim 2, wherein the epoxy resin (i) has about 172 to about 179 EEW.

6. The adhesive composition according to any one of claims 1 to 5, wherein the epoxy resin (i) comprises a diglycidyl ether of a substituted or unsubstituted bisphenol, preferably a diglycidyl ether of bisphenol A (DGEBA), a diglycidyl ether of bisphenol F (DGEBF), or a combination thereof.

7. An adhesive composition according to any one of claims 1 to 6, comprising one epoxy resin.

8. An adhesive composition according to any one of claims 1 to 6, comprising two epoxy resins.

9. An adhesive composition according to any one of claims 1 to 6, comprising three epoxy resins.

10. An adhesive composition according to any one of claims 1 to 6, comprising four or more epoxy resins.

11. The adhesive composition according to any one of claims 1 to 10, comprising about 30 to about 60 by weight of the epoxy resin (i) based on the weight of the composition.

12. The adhesive composition according to claim 1, wherein the latent reagent is a thermally activated reagent containing a modified polymer tertiary amine having an activation temperature in the range of about 120°C to about 138°C.

13. The adhesive composition according to claim 12, wherein the latent reactant is a thermally activated reagent comprising a tertiary amine, a polyhydroxyphenylalkyl polymer resin, and an auxiliary organic agent.

14. The adhesive composition according to claim 12 or 13, wherein the auxiliary organic agent comprises an oligomer or polymer containing an acrylic portion.

15. The adhesive composition according to claim 12 or 13, wherein the tertiary amine comprises at least one hydroxyl substituent.

16. The adhesive composition according to claim 12 or 13, wherein the tertiary amine comprises an aromatic ring and an acrylate.

17. The adhesive composition according to claim 12 or 13, wherein the tertiary amine comprises an aromatic ring having a 1-3 tertiary amine functional group and optionally further comprises at least one hydroxyl substituent.

18. The adhesive composition according to claim 12 or 13, wherein the tertiary amine comprises one or more mono-, di-, or tris-(dialkylaminomethyl)-phenols.

19. The adhesive composition according to claim 12 or 13, wherein the tertiary amine comprises 2,4,6-tris-(dimethylaminomethyl)-phenol.

20. The adhesive composition according to any one of claims 1 to 19, comprising about 0.5 to about 5% by weight of the latent reactant based on the weight of the composition.

21. The adhesive composition according to any one of claims 1 to 20, wherein the modified urea accelerator comprises dimethylurea.

22. The adhesive composition according to any one of claims 1 to 21, comprising about 0.2 to about 3% by weight of the modified urea accelerator based on the weight of the composition.

23. The adhesive composition according to any one of claims 1 to 22, comprising about 2 to about 6% by weight of the dicyandiamide based on the weight of the composition.

24. The adhesive composition according to any one of claims 1 to 23, wherein the reinforcing agent comprises at least one carboxyl-terminated butadiene acrylonitrile (CTBN), and optionally has DGEBF and / or DGEBA added to it.

25. The adhesive composition according to claim 24, comprising about 1 to about 20% by weight of the reinforcing agent based on the weight of the composition.

26. The adhesive composition according to any one of claims 1 to 25, further comprising a core-shell rubber (CSR) particle solid reinforcing agent optionally dispersed in an epoxy resin.

27. The adhesive composition according to claim 26, wherein the CSR particles are nanocore-shell rubber particles.

28. The adhesive composition according to claim 26 or 27, wherein the CSR particles are dispersed in DGEBA.

29. The adhesive composition according to claim 28, comprising about 40 to about 45% by weight of CSR particles, based on the weight of CSR particles in DGEBA.

30. The adhesive composition according to any one of claims 26 to 29, comprising about 20 to about 25% by weight of CSR particles based on the weight of the composition.

31. The adhesive composition according to claims 1 to 30, further comprising a softening agent, wherein the softening agent is a polyetheramine-DGEBA adduct.

32. An adhesive composition according to any one of claims 1 to 31, comprising a polyurethane reinforcing agent.

33. The adhesive composition according to claim 32, wherein the polyurethane reinforcing agent is a block-type polyurethane reinforcing agent.

34. The adhesive composition according to claim 32 or 33, wherein the reinforcing agent comprises one or more polyurethane prepolymers based on poly(tetramethylene ether) glycol and / or polybutadiene, and optionally end-capacitated.

35. The adhesive composition according to any one of claims 32 to 34, comprising about 0.1 to about 34% by weight of the polyurethane reinforcing agent based on the weight of the composition.

36. The adhesive composition according to any one of claims 32 to 35, comprising about 2 to about 30% by weight of the polyurethane reinforcing agent based on the weight of the composition.

37. The adhesive composition according to any one of claims 1 to 36, further comprising a phosphorus-based adhesion promoter.

38. The adhesive composition according to claim 37, wherein the phosphorus-based adhesion promoter comprises substituted or unsubstituted triphenyl phosphate.

39. The adhesive composition according to claim 37, wherein the phosphorus-based adhesion promoter comprises at least one tris(alkylphenyl) phosphate.

40. The adhesive composition according to claim 37, wherein the phosphorus-based adhesion promoter comprises one or more tris(4-isopropylphenyl)phosphate, tris[4-(2-methylpropyl)phenyl]phosphate, or triphenyl phosphate.

41. The adhesive composition according to any one of claims 37 to 40, comprising about 0.5 to about 5% by weight of the phosphorus-based adhesion promoter based on the weight of the composition.

42. The adhesive composition according to any one of claims 1 to 41, further comprising a silane adhesion promoter.

43. The adhesive composition according to claim 42, wherein the silane adhesion promoter is 3-glycidyloxypropyltrimethoxysilane (GLYMO).

44. The adhesive composition according to claim 42 or 43, comprising about 0.1 to about 0.3% by weight of the silane adhesion promoter based on the weight of the composition.

45. The adhesive composition according to any one of claims 1 to 44, wherein the filler is an inorganic filler.

46. The adhesive composition according to claim 45, wherein the inorganic filler is a desiccant, a thixotrope, or a combination thereof.

47. The adhesive composition according to claim 45 or 46, wherein the inorganic filler is calcium oxide, calcium metasilicate, mica, mixed mineral thixotrope, hydrophobic surface-treated fumed silica, hollow glass microspheres, or a combination thereof.

48. The adhesive composition according to any one of claims 45 to 47, comprising about 1 to about 35% by weight of the inorganic filler based on the weight of the composition.

49. The adhesive composition according to any one of claims 45 to 47, comprising about 1 to about 10% by weight of calcium oxide based on the weight of the composition.

50. The adhesive composition according to any one of claims 45 to 47, comprising about 1 to about 10% by weight of calcium metasilicate based on the weight of the composition.

51. An adhesive composition according to any one of claims 45 to 47, comprising about 0.1 to about 1% by weight of mica based on the weight of the composition.

52. The adhesive composition according to any one of claims 45 to 47, comprising about 0.1 to about 1% by weight of mixed mineral thixotrope based on the weight of the composition.

53. The adhesive composition according to any one of claims 45 to 47, comprising about 1 to about 8% by weight of hydrophobic surface-treated fumed silica based on the weight of the composition.

54. The adhesive composition according to any one of claims 45 to 47, comprising about 0.5 to about 3% by weight of hollow glass microspheres based on the weight of the composition.

55. The adhesive composition according to any one of claims 1 to 54, wherein the epoxy resin different from (i) is a novolac epoxy resin having an EEW in the range of 172 to 225.

56. The adhesive composition according to any one of claims 1 to 55, wherein the adhesive composition does not contain an accelerator which is imidazole, dihydroxybenzene, adipic anhydride, phosphonium ionic liquid, phenol-based blocked tertiary amine that does not contain acrylate, polyamine salt of a polyhydric phenol, or a combination thereof.

57. The adhesive composition according to any one of claims 1 to 56, which is storage stable at room temperature and preferably stable in the range of 15°C to 30°C.

58. A method for producing a cured adhesive, comprising heating an adhesive composition according to any one of claims 1 to 57 to a temperature of about 140°C to about 150°C.

59. The method according to claim 58, wherein the adhesive composition is heated at approximately 140°C for 15 minutes.

60. The method according to claim 58 or 59, further comprising heating at 190°C for 60 minutes.

61. A product manufactured using the method described in any one of claims 58 to 60.

62. A product comprising a first surface and a second surface, wherein a cured layer of the adhesive composition according to any one of claims 1 to 57 is sandwiched between the first surface and the second surface and bonded them together.

63. The product according to claim 62, wherein one or both of the first surface and the second surface include a metal surface, a composite surface, or a combination thereof.

64. The product according to claim 62, wherein one or both of the first surface and the second surface include a surface made of metal, coated metal, aluminum, plastic, filled plastic, or fiberglass.

65. A steel or aluminum surface containing the adhesive composition according to any one of claims 1 to 57.

66. The steel or aluminum surface according to claim 65, wherein the adhesive composition is adhered to the surface.

67. A steel or aluminum surface according to claim 65, which is a part of an aircraft, automobile, ship, locomotive, or construction vehicle, preferably an automobile part.

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