Two-component quick-drying adhesive

Abstract

The present teachings provide an adhesive formulation including a part A that includes an epoxy resin and a part B that includes an acidic phosphorus component, wherein the adhesive has a T-peel of at least about 2.5 N / mm, as measured according to ASTM D1876.

Description

[Technical field]

[0001] The present teachings generally relate to fast-curing two-component adhesives that cure at ambient temperatures that contain some epoxide functionality while providing improved T-peel resistance and adhesion to a range of substrates. The invention employs the use of phosphoric acid and / or phosphate esters and / or other acidic components as primary activators and curing agents that react with a mixture that contains an epoxide-functional material as the primary co-reactant. [Background technology]

[0002] Fast-setting epoxy adhesives, including a product category called 5-minute epoxies, are well known commercially. It is generally known that 5-minute epoxies cure quickly but do not have an attractive set of cohesive properties. To date, there is a significant trade-off between rapid reaction time and reduced physical properties and compromised durable adhesion to various substrates. A variety of curing agents, hardeners, or activators are used to make these adhesives, which are commonly found in hardware stores and DIY centers. Although the adhesives can be made with high shear strength, their use as assembly adhesives in manufacturing and durable repair methods is limited due to the adhesives' lack of peel resistance, one common evaluation method being the T-peel test. This lack of peel resistance limits uses where bending, peeling, and off-axis loading can be important factors. In addition, the adhesive quality typically varies for a range of substrates with lap shear strengths that are not consistent by substrate type as a manifestation of this phenomenon.

[0003] Notwithstanding the above teachings, a need exists for fast drying adhesives with the proper blend of granular reinforcing agents and softeners such that the physical properties are improved as a result of the proper blending of an immiscible elastomeric reinforcing phase with sufficient matrix plasticization.

[0004] The present teachings provide one or more of the benefits discussed above. The adhesive materials of the present teachings can be utilized to provide fast drying adhesives having one or more of improved peel resistance, improved lap shear, and improved adhesion to a variety of substrates, including in the presence of contaminants. Summary of the Invention [Means for solving the problem]

[0005] The present teachings provide an adhesive that includes a part A that includes an epoxy resin and a part B that includes an acidic phosphorus component. The cured adhesive has a T-peel of at least about 2.5 N / mm, as measured according to ASTM D1876.

[0006] The teachings herein are further directed to a curable adhesive formulation that includes a Part A that includes one or more epoxy resins and a Part B that includes an acidic phosphorus component. The adhesive includes one or more of calcium carbonate, minerals, reinforcing fibers, hydrophobic silica, or any combination thereof.

[0007] The teachings herein are further directed to a curable adhesive formulation that includes a Part A that includes one or more epoxy resins and a Part B that includes an acidic phosphorus component. The cured adhesive has a T-peel of at least about 2.5 N / mm, as measured according to ASTM D1876.

[0008] The cured adhesive may provide an assembly having a lap shear of at least about 15 MPa as measured according to EN 2243-1.

[0009] The acidic phosphorus component may include one or more phosphate esters, phosphoric acid, polyphosphoric acid, phosphorus pentoxide, or any combination thereof. The one or more phosphate esters may include a first phosphate ester, a second phosphate ester, a third phosphate ester, or any combination thereof.

[0010] The one or more phosphate esters may be, independently of one another, a reaction product of phosphoric acid with an alcohol, an epoxide group of a phosphate ester precursor (i.e., a component that has not yet reacted with phosphoric acid), a monoepoxide functional molecule, a glycidyl ether of cashew nut shell liquid (CNSL), phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, and / or an epoxidized para-tertiary butyl phenol.

[0011] The one or more phosphate esters may be present in an amount of about 0.1% by weight to about 30% by weight of B-side, preferably about 10% by weight to about 14% by weight of B-side. The at least one phosphate ester may be present in an amount of about 10% by weight to about 60% by weight of B-side, preferably about 25% by weight to about 35% by weight of B-side, more preferably about 28% by weight to about 32% by weight of B-side. The at least one phosphate ester may be present in an amount of about 5% by weight to about 40% by weight of B-side, preferably about 15% by weight to about 25% by weight of B-side, more preferably about 18% by weight to about 22% by weight of B-side. The at least one phosphate ester may be present in an amount of about 10% by weight to about 65% by weight of B-side, preferably about 35% by weight to about 45% by weight of B-side.

[0012] Part B may include one or more non-phosphorus-containing acids or derivatives, one or more acid anhydrides, one or more additives, one or more monomers, or any combination thereof.

[0013] The one or more additives may include a mineral, a reinforcing fiber, a fumed silica, or any combination thereof. The adhesive may include calcium carbonate. The adhesive may include an elastomeric material. The adhesive may include calcium carbonate, a mineral, a reinforcing fiber, a hydrophobic silica, or any combination thereof.

[0014] The two-part system may include calcium carbonate present in an amount of from about 1% to about 25% by weight of part A, preferably from about 4% to about 18% by weight of part A, and more preferably from about 8% to about 12% by weight of part A.

[0015] The two-part system may include a core-shell material. The two-part system may include a hydrophobic silica. The two-part system may include a platelet alumina.

[0016] The one or more epoxy resins may include one or more liquid epoxy resins, one or more flexible epoxy resins, one or more epoxy phenol novolac resins, one or more aliphatic multifunctional epoxy resins, one or more reactive diluents, one or more silane modified epoxy resins, or any combination thereof.

[0017] 10. The adhesive of any preceding claim, wherein the one or more epoxy resins comprise one or more liquid epoxy resins.

[0018] 22. The adhesive of claim 21, wherein the one or more liquid epoxy resins are, independently of one another, a reaction product of epichlorohydrin with a bisphenol, preferably bisphenol A, bisphenol F or both.

[0019] The one or more liquid epoxy resins may have an epoxide equivalent weight of about 100 g / eq to about 1000 g / eq, an epoxide percentage of about 20 to about 25, and / or a viscosity of about 10 cP to about 100,000 cP at 25° C., measured according to ASTM D1652-97. The one or more liquid epoxy resins may be present in an amount of about 4% to about 50% by weight of Part A. The one or more liquid epoxy resins may be present in an amount of about 10% to about 30% by weight of Part A. The one or more liquid epoxy resins may be present in an amount of about 8% by weight of Part A.

[0020] The one or more epoxy resins may preferably comprise, independently of one another, one or more flexible epoxy resins selected from difunctional glycidyl ether epoxy resins, modified BPA-based epoxy resins, multifunctional epoxidized polybutadiene resins, or any combination thereof. The one or more flexible epoxy resins may, independently of one another, have an epoxide equivalent weight of about 260 to about 500, measured according to ASTM D1652-97, and / or a viscosity of about 700 cP to about 500,000 cP at 25° C., measured according to ASTM D445. The one or more flexible epoxy resins may be present in an amount of about 10% to about 50% by weight of Part A, preferably about 35% to about 45% by weight of Part A. The one or more flexible epoxy resins may include a difunctional glycidyl ether epoxy resin in an amount of about 10% to about 18% by weight of Part A, a modified BPA-based epoxy resin in an amount of about 8% to about 16% by weight of Part A, and a multifunctional epoxidized polybutadiene resin in an amount of about 8% to about 16% by weight of Part A.

[0021] The one or more epoxy resins may include one or more epoxy phenol novolac resins that may have an epoxide equivalent weight of about 165 g / eq to about 183 g / eq, as measured according to ASTM D1652-97, an average epoxy functionality of about 2.1 to about 6.5, and / or a viscosity of about 18,000 cP to about 30,000 cP at 25° C., as measured according to ASTM D445.

[0022] The one or more epoxy phenol novolac resins may be present in an amount of about 30% to about 50% by weight of Part A, preferably about 35% to about 45% by weight of the first component or Part A, and more preferably about 38% to about 42% by weight of Part A.

[0023] The one or more epoxy phenol novolac resins may include an about 3.6 functional epoxy phenol novolac resin present in an amount of about 2% to about 18% by weight of Part A and an about 6.5 functional epoxy novolac resin present in an amount of about 22% to about 32% by weight of Part A, an about 3.6 functional epoxy phenol novolac resin present in an amount of about 15% by weight of Part A and an about 6.5 functional epoxy novolac resin present in an amount of about 28% by weight of Part A, and / or a ratio of about 1:2 to about 1:3 of the about 3.6 functional epoxy phenol novolac resin and the about 6.5 functional epoxy phenol novolac resin.

[0024] The one or more epoxy resins may include one or more aliphatic multifunctional epoxy resins, preferably epoxidized sorbitol. The one or more aliphatic multifunctional epoxy resins may have an epoxide equivalent weight of about 160 g / eq to about 195 g / eq, as measured according to ASTM D1652-97, and / or a viscosity of about 200 cP to about 18,000 cP at 25° C., as measured according to ASTM D445. The one or more aliphatic multifunctional epoxy resins may be present in an amount of about 5% to about 20% by weight of Part A, preferably 8% to about 16% by weight of Part A, and more preferably about 10% to about 14% by weight of Part A.

[0025] The one or more epoxy resins may include cashew nut shell liquid, preferably a glycidyl ether of cashew nut shell liquid, more preferably a glycidyl ether of cardanol. The one or more epoxy resins may include one or more reactive diluents, preferably polyglycol diglycidyl ether, trimethylolethane triglycidyl ether (either), or both. The one or more reactive diluents may be present in an amount of about 5% to about 20% by weight of Part A, preferably about 8% to about 16% by weight of Part A, more preferably about 10% to about 14% by weight of Part A.

[0026] The one or more epoxy resins may include one or more epoxy-functional silanes or silane-modified epoxy resins. The one or more silane-modified epoxy resins may be present in an amount of about 1% to about 15% by weight of Part A, preferably about 2% to about 6% by weight of Part A, and more preferably about 4% by weight of Part A.

[0027] The cured adhesive may provide an assembly having a lap shear of at least about 15 MPa as measured according to EN2243-1. The adhesive may include calcium carbonate. The adhesive may include an elastomeric material. The adhesive may include one or more of calcium carbonate, minerals, reinforcing fibers, hydrophobic silica, or any combination thereof. The adhesive may include calcium carbonate present in an amount of about 2% to about 25% by weight of Part A. The adhesive may include a core-shell material. The adhesive may include one or more liquid epoxy resins including a reaction product of epichlorohydrin and bisphenol A. The cured adhesive may have a tensile modulus of at least 1000 MP as measured according to ISO527.

[0028] Part A may include epoxidized linseed oil. None of the components of Part B may be physically separate from the acidic phosphorus component. Part A and Part B may be substantially free of fibrous material. The epoxy resin may include an aliphatic epoxy resin. Part A may include epoxidized linseed oil in an amount greater than 0.5% but less than 10%. Part A may include epoxidized linseed oil in an amount greater than 1 percent but less than 6 percent. Part A may include bisphenol A epoxy resin in an amount of at least 0.5%.

[0029] Part A may include bisphenol A epoxy resin in an amount of at least 2.5%. Part A may include bisphenol A epoxy and epoxidized linseed oil in a ratio of about 1 part bisphenol A epoxy:2 parts epoxidized linseed oil to about 2 parts bisphenol A epoxy:1 part epoxidized linseed oil. Part A may include bisphenol A epoxy and epoxidized linseed oil in a ratio of about 1 part bisphenol A epoxy:1 part epoxidized linseed oil. Part A may include difunctional glycidyl ether epoxy resin and epoxidized linseed oil in a ratio of about 3 parts difunctional glycidyl ether epoxy resin:1 part epoxidized linseed oil. Part A and Part B may be present in a ratio of about 4 parts Part A to about 1 part Part B.

[0030] The adhesive may cure at ambient temperature (about 20° C. to about 23° C.). The rate at which the adhesive cures may be increased by application of heat.

[0031] The teachings herein are further directed to a method of adhering a first substrate to a second substrate, comprising the steps of placing an adhesive on the first substrate and placing the second substrate in contact with the adhesive within 5 minutes, Part A of the adhesive may be mixed with Part B of the adhesive within 5 minutes of placing the adhesive on the first substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The present teachings satisfy one or more of the above needs through improved compositions and methods described herein. The description and examples provided herein are intended to enable those skilled in the art to acquire the teachings, their principles, and their practical applications. Those skilled in the art can adapt and apply the numerical forms of the teachings as best may suit the requirements of a particular use. Thus, the specific embodiments of the present teachings as shown are not intended to be exhaustive or limiting of the teachings. Thus, the scope of the teachings should not be determined with reference to the above description, but instead with reference to the appended claims, together with the full scope of equivalents to which such claims are entitled. The disclosures of all papers and references, including patent applications and publications, are incorporated by reference for all purposes. Other combinations are also possible as gleaned from the following claims, which are also incorporated by reference in this description.

[0033] This application claims the benefit of the filing date of U.S. Provisional Application No. 63 / 334,350, filed April 25, 2022, the contents of which are incorporated herein by reference in their entirety for all purposes.

[0034] The following teachings describe a significant improvement in the overall performance of fast-curing adhesives through novel non-traditional hardener systems. For example, crosslinked epoxy resins made from traditional epoxy resins are known to be strong and stiff, but are often brittle, i.e., low strain at break materials with poor impact resistance. This property can produce adhesives with high shear strength but poor peel resistance and low fracture toughness when bonding metal substrates. The low fracture toughness of these systems typically affects the low peel resistance. No single component alone provides improved peel resistance. Although improved peel resistance can be the result of multiple components and interactions, the novel hardener systems used in these product types can be important to obtain improved peel resistance while maintaining reaction speed.

[0035] The teachings herein further describe the use of phosphoric acid and / or phosphoric acid esters, and other acidic components such as carboxylic acids and acid anhydrides, as primary activators to make two-component (Part A and Part B) adhesives that cure at ambient temperature. The adhesives can have some epoxide functionality, improved T-peel resistance, and adhesion to various substrates. The important criteria is that the additional components of the hardener part (Part B) must be compatible with the phosphoric acid or phosphoric acid ester and cannot physically separate from the acid or phosphoric acid ester. Acids in general or any molecules that can be easily deprotonated are known to initiate ring opening in epoxy resins, subsequent polymerization progression, and crosslinking. The resulting increase in molecular weight is the basis for the mechanical and adhesive properties of the final product. Molecules with an average functionality greater than 2, whether they are proton-free molecules, epoxy-functional molecules, or any combination of the two, are capable of creating a three-dimensional crosslinked network when reacted through their functional groups.

[0036] Part A may include one or more epoxy resins, one or more additives, one or more monomers, or both. The one or more epoxy resins may include one or more liquid epoxy resins, one or more flexible epoxy resins, one or more epoxy phenol novolac resins, one or more aliphatic multifunctional epoxy resins, one or more reactive diluents, one or more silane-modified epoxy resins, one or more monomers, or any combination thereof. The one or more additives may include one or more toughening agents (e.g., core-shell polymer particles), metal carbonates, minerals, reinforcing fibers, fumed silica, platelet alumina, or any combination thereof.

[0037] Part B may include one or more phosphate esters, phosphoric acid, polyphosphoric acid, phosphorus pentoxide, one or more non-phosphorus-containing acids or derivatives, one or more acid anhydrides, one or more additives, one or more monomers, or any combination thereof. The one or more phosphate esters may include a first phosphate ester, a second phosphate ester, a third phosphate ester, or any combination thereof. The one or more additives may include minerals, reinforcing fibers, fumed silica, or any combination thereof.

[0038] Phosphoric acid works well to initiate and propagate epoxy crosslinks. However, there are problems with using this acid as the sole curing agent for some types of formulated products. This is because the volumetric mix ratio between resin and hardener may be too different due to its low molecular weight and high functionality compared to most common epoxy molecules. Typically, 1:1 mix ratios are often most preferred due to their ease of handling and the generally increased resistance to off-ratio mixes. Mix ratios of 2:1, 4:1, and even 10:1 may be acceptable, but higher mix ratios require more precise dosing of inferior components.

[0039] The high functionality and low pH of phosphoric acid also contribute to a fast reaction rate. In automated processes, fast-setting adhesives that cure in less than 5 minutes may be desirable. However, most manual assembly processes require a certain amount of time for mixing and application of the adhesive and subsequent assembly of the parts. In addition, as mentioned above, fast-setting adhesives have a performance trade-off. The decrease in performance is due in part to a decrease in the wetting time of the adhesive. That is, the less time the adhesive needs to be in intimate contact with the substrate before molecular weight increase and subsequent crosslinking can begin. A rapid increase in viscosity can also prevent adhesion from occurring. Similarly, as discussed with respect to epoxidized carboxyl-terminated acrylonitrile-butadiene rubber, a fast reaction rate reduces the time available for phase separation of a distinct secondary phase that can be useful for improving physical properties, particularly increasing peel resistance.

[0040] Due to the rapid bond formation from the crosslinking of the epoxy resin, if there is sufficient material mass, a high exothermic peak can result. The same amount of energy can be produced from a slower curing system, but the heat will have more time to dissipate or transfer to the substrate, surrounding material, or air, resulting in a lower exothermic peak.

[0041] US Patent No. 6,730,713 describes a material comprising an epoxy resin, a phosphoric acid and a metal carbonate to form a foamed-in-place material, and WO2016 / 149700 describes an esterified acid for use in polymeric materials. The teachings herein describe structural adhesives with improved T-peel resistance and desirable adhesion to multiple substrate types. Some of the teachings below describe non-foamed or minimally foamed materials that have a final density similar to the combination of the densities of the two initial components, although more highly foamed materials can be made whose final density is significantly lower than the combination of the densities of the two initial components.

[0042] As described in WO2016 / 149700, by pre-reacting phosphoric acid with epoxy-functional molecules, many of the problems associated with using concentrated phosphoric acid as the sole curing agent can be eliminated or reduced. Higher molecular weight molecules with reduced reactivity react slower and have fewer reactive functional groups per unit volume, lowering the exothermic peak of the reaction mixture. The combination of higher molecular weight and reduced reactivity can also affect the volumetric mix ratio between the epoxy resin and the curing agent, allowing it to approach 1:1. In addition, the reaction product of phosphoric acid with epoxy is more viscous than phosphoric acid alone. This typically matches the viscosity of the epoxide-functional side groups more closely, allowing for better mixing of the two. Also, material performance and properties can be tailored by the selection of the epoxy-functional molecules used to pre-react with the phosphoric acid, allowing material properties to be obtained from the combination of both the resin and additive components of the adhesive. These attributes of using phosphoric acid and or esters of phosphoric acid allow for adhesives that react quickly and still adhere to a wide range of substrates.

[0043] Phosphoric acid and / or esters of phosphoric acid can be used as hardeners according to the teachings herein. Other chemical structures may be combined with phosphoric acid or acid esters to improve the mechanical properties, adhesive strength, processing characteristics, and cure kinetics of the formulated product. Neutral pH esters can also be used. In one embodiment, carboxylic acid functional components may be combined with the hardener. Acid anhydrides may also be added to the hardener liquid of the formulation. These additives may be used for their contribution to the final material properties or to adjust the pH of the hardener part of the formulation. The use of Epodil® LV5, a non-reactive xylene-formaldehyde diluent in combination with phosphoric acid and / or phosphoric acid esters, is an example. Other non-reactive additives may also be used, whether they are organic or inorganic, e.g., minerals. Typically, inorganic thixotropes such as fumed silica or clays are used to impart non-Newtonian rheological behavior. Organic thixotropes such as polymeric fibers may also be used.

[0044] By reacting phosphoric acid with epoxy to form statistically monosubstituted acid-esters, the average number of reactive hydrogens for further epoxy reaction is reduced to two. To form a crosslinked network, the average functionality of the system needs to be greater than two, but not much greater than two. This can be achieved by adding small amounts of unreacted phosphoric acid, polyphosphoric acid or polyphosphate ester to the hardener, or by using multifunctional epoxy resins, i.e., epoxy resins with more than two oxirane rings in the molecule. Phenol novolac or cresol novolac resins can be used for this purpose. Multifunctional aliphatic resins such as epoxidized soybean oil also work. At least one embodiment of this patent uses both unreacted phosphoric acid and multifunctional epoxy resins in combination.

[0045] The one or more phosphate esters may be one or more customized phosphate esters. The one or more customized phosphate esters may be produced by reacting phosphoric acid with various alcohols. The one or more customized phosphate esters may be produced by reacting phosphoric acid with an epoxide group of a phosphate ester precursor (i.e., a component that has not yet reacted with phosphoric acid). The one or more customized phosphate esters may be produced by reacting phosphoric acid with a glycidyl ether of cashew nut shell liquid (CNSL), such as that sold under the trade name Cardolite® LITE 2513HP, commercially available from Cardolite Corporation, Monmouth Junction NJ. The one or more customized phosphate esters may be produced by reacting phosphoric acid with a phenyl glycidyl ether, such as that sold under the trade name ERISYS® GE-13, commercially available from CVC Thermoset Specialties, Moorestown, NJ. The one or more customized phosphate esters can be produced by reacting phosphoric acid with 2-ethylhexyl glycidyl ether, such as that sold under the trade name ERISYS® GE-6, commercially available from CVC Thermoset Specialties, Moorestown, NJ. The one or more customized phosphate esters can be produced by reacting phosphoric acid with epoxidized para-tertiary butyl phenol, such as that sold under the trade name ERISYS® GE-11, commercially available from CVC Thermoset Specialties, Moorestown, NJ, or any other monofunctional epoxy. The one or more customized phosphate esters can be the reaction product of phosphoric acid with monoepoxide functional molecules in general.

[0046] The one or more phosphate esters may be one or more commercially available phosphate esters that are typically made from the reaction of various alcohols or unsaturated hydrocarbons with polyphosphoric acid and or phosphorus pentoxide. The one or more commercially available phosphate esters, when placed in Part B instead of the customized phosphate ester, may result in a curable composition that reacts slower and foams, possibly due to lower levels of free phosphoric acid and thus higher pH of Part B. The reaction and foaming of the one or more commercially available phosphate esters may be improved (i.e., reaction rate may be increased) by adding phosphoric acid to Part B. The one or more commercially available phosphate esters have a pH of about 1 to about 4 in aqueous solution. The one or more commercially available phosphate esters may have a viscosity of about 200 cP to about 42,500 cP at 25° C., measured according to ASTM D445. The one or more commercially available phosphate esters may be nonylphenol ethoxylated phosphate esters. The one or more commercially available phosphate esters may be butyl phosphate esters. Examples of suitable commercially available phosphate esters may be those sold under the trade names Dextrol™ OC-110, Dextrol™ OC-40, and Strodex™ MO-100, commercially available from Ashland, Inc. (Covington, KY). A further example of a suitable commercially available phosphate ester may be n-butyl acid phosphate, commercially available from IsleChem (Grand Island, NY).

[0047] A commercially available phosphate ester may be present in Part B. The one or more commercially available phosphate esters may be present in an amount of about 5% to about 50% by weight of Part B. The one or more commercially available phosphate esters may be present in an amount of about 0.1% to about 30% by weight of Part B. The one or more commercially available phosphate esters may be present in an amount of about 10% to about 14% by weight of Part B. The one or more commercially available phosphate esters may be present in an amount of about 12% by weight of Part B.

[0048] The one or more phosphate esters may be produced by reaction of a range of stoichiometric ratios of phosphate ester precursor to phosphoric acid. The one or more phosphate esters may be produced by reaction of about 0.7:1 phosphate ester precursor to phosphoric acid to about 1:0.7 phosphate ester precursor to phosphoric acid. The one or more phosphate esters may be produced by reaction of about 0.8:1 phosphate ester precursor to phosphoric acid to about 1:0.8 phosphate ester precursor to phosphoric acid. The one or more phosphate esters may be produced by reaction of about 0.9:1 phosphate ester precursor to phosphoric acid to about 1:0.9 phosphate ester precursor to phosphoric acid. The one or more phosphate esters may be produced by reaction of about 1:1 phosphate ester precursor to phosphoric acid. The one or more phosphate esters may be produced by reaction of about 0.8:1 phosphate ester precursor to phosphoric acid.

[0049] The one or more phosphate esters may be selected from mono-esters, di-esters, or triesters as shown below. The one or more phosphate esters may be a combination of mono-esters, di-esters, and triesters.

[0050] [ka]

[0051] The one or more phosphate esters can result from the reaction of an epoxide group with phosphoric acid as shown below:

[0052] [ka]

[0053] Part B may include one or more phosphate esters, one or more phosphate ester precursors, or both. Part B may include one or more phosphate ester precursors that may be combined with phosphoric acid prior to combination with Part A. Part B may include one or more phosphate esters that are pre-reacted (i.e., reaction of an epoxide with a phosphate) prior to addition to Part B.

[0054] The adhesive may include two or more phosphate esters. At least one phosphate ester may be a reaction product of phosphoric acid and a glycidyl ether of cashew nut shell liquid (CNSL) (e.g., Cardolite® LITE 2513HP). At least one phosphate ester may be a reaction product of about 1:1 stoichiometric amounts of 2-ethylhexyl glycidyl (e.g., ERISYS® GE-6) to phosphoric acid. At least one phosphate ester may be a reaction product of 0.8:1 stoichiometric amounts of phosphoric acid and 2-ethylhexyl glycidyl ether (e.g., ERISYS® GE-6). However, there are numerous possibilities for the first, second or third phosphate ester.

[0055] The at least one phosphate ester may be present in an amount of about 10% to about 60% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 25% to about 35% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 28% to about 32% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 32% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 5% to about 40% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 15% to about 25% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 18% to about 22% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 21% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 10% to about 65% by weight of the solution B. The at least one phosphate ester may be present in an amount of about 35% to about 45% by weight of Part B. The at least one phosphate ester may be present in an amount of about 42% by weight of Part B. The at least one phosphate ester may be present in an amount of about 58% by weight of Part B. The at least one phosphate ester may be present in an amount of about 60% by weight of Part B.

[0056] Part B may include phosphoric acid. The phosphoric acid may be ortho-phosphoric acid, polyphosphoric acid, or both. The phosphoric acid may be the free acid in one or more phosphate esters, added independently from one or more phosphate esters, or both. The addition of phosphoric acid to Part B may result in increased expansion (e.g., foaming) of the resulting reaction product. The addition of phosphoric acid to Part B may increase the reactivity of the two-part system to help maintain a desired level of expansion, hardening, or both when temperatures are below 23°C.

[0057] The independently added phosphoric acid may be in an aqueous solution in an amount of 85% or greater (i.e., "reagent grade"). The independently added phosphoric acid may be present in an amount of about 1% to about 20% by weight of Solution B. The independently added phosphoric acid may be present in an amount of about 2% to about 6% by weight of Solution B. The independently added phosphoric acid may be present in an amount of about 4% by weight of Solution B.

[0058] The one or more phosphate esters produced from the reaction of phosphoric acid with a phosphate ester precursor may include free acid. The one or more phosphate esters may have about 1% or more free acid, about 3% or more free acid, about 5% or more free acid, about 15% or less free acid, about 13% or less free acid, or even about 11% or less free acid.

[0059] The two-part system may foam and produce a gas release as a result of the reaction of the metal carbonate or bicarbonate with the acid upon addition of parts A and B (e.g., carbon dioxide serves as a chemical foaming agent). Such a reaction mechanism is described in U.S. Patent No. 5,648,401, which is incorporated herein by reference for all purposes.

[0060] The reaction, foaming, or both can occur at temperatures of about 70° C. or less, about 50° C. or less, about 30° C. or less, about 20° C. or less, or even about 0° C. or less. The curing, foaming, or both can occur at temperatures of about 0° C. or more, about 10° C. or more, or even about 20° C. or more. The curing, foaming, or both can occur at temperatures of about 10° C. to about 35° C. The curing, foaming, or both can occur at temperatures of about 10° C. The curing, foaming, or both can occur at room temperature (e.g., temperatures of about 15° C. to about 25° C.). The curing, foaming, or both can occur at a temperature of about 23° C.

[0061] The present teachings contemplate relatively fast cure times, foaming times, or both, as compared to other curing agents or curing agent systems that occur without the addition of a stimulus (e.g., at room temperature). The cure time of the reaction product may be 30 minutes or less, 20 minutes or less, 2 minutes or more, 8 minutes or more, or even 16 minutes or more. The cure time of the resulting reaction product may be from about 5 minutes to about 20 minutes. The cure time of the resulting reaction product may be about 10 minutes. The cure time of the resulting reaction product may be about 7 minutes. The cure time of the resulting reaction product may be about 5 minutes.

[0062] Part A may include one or more epoxide-functional materials (i.e., one or more epoxy resins). The one or more epoxy resins may be any conventional dimeric, oligomeric, or polymeric epoxy resin. The one or more epoxy resins may contain at least one epoxide functional group (i.e., monofunctional), or may contain two or more epoxide functional groups (i.e., multifunctional). The one or more epoxy resins may contain one or more epoxide functional groups, two or more epoxide functional groups, three or more epoxide functional groups, or even four or more epoxide functional groups. The one or more epoxy resins may be modified epoxy resins (e.g., silane-modified, elastomer-modified, etc.). The one or more epoxy resins may be aliphatic, cycloaliphatic, aromatic, etc., or any combination thereof. The one or more epoxy resins may be supplied as a solid (e.g., pellets, chunks, pieces, etc., or any combination thereof) or liquid (e.g., liquid epoxy resin). However, if solid resins are used, they may first be dissolved in a liquid resin or other suitable solvent. As used herein, unless otherwise stated, an epoxy resin is solid if it is solid at a temperature of 23°C, and liquid if it is liquid at a temperature of 23°C. The one or more epoxy resins may include one or more liquid epoxy resins, one or more flexible epoxy resins, one or more epoxy phenol novolac resins, one or more aliphatic multifunctional epoxy resins, one or more reactive diluents, one or more silane-modified epoxy resins, or any combination thereof.

[0063] The two-part system may include one or more liquid epoxy resins. The one or more liquid epoxy resins may serve as a base for the epoxy resin component. The one or more liquid epoxy resins may be a reaction product of epichlorohydrin (hereinafter "EPH") with any conventional bisphenol. The one or more liquid epoxy resins may be a reaction product of EPH with bisphenol A (hereinafter "BPA"), bisphenol F (hereinafter "BPF"), or both. The one or more liquid epoxy resins (which may be standard or commodity liquid epoxy resins) may have an epoxide equivalent weight (hereinafter "EEW") of about 100 g / eq to about 1000 g / eq as measured according to ASTM D1652-97. The one or more liquid epoxy resins may have an epoxide percentage of about 20 to about 25. The one or more liquid epoxy resins may have a viscosity of about 10 cP to about 100,000 cP at 25° C., measured according to ASTM D445. An example of a suitable BPA-based liquid epoxy resin may be DER™ 331, commercially available from The Olin Corporation, Clayton, Mo. An example of a suitable BPF-based liquid epoxy resin may be YDF-170, commercially available from Kukdo Chemical, South Korea.

[0064] The one or more liquid epoxy resins may be present as part of Part A. The one or more liquid epoxy resins may be present in an amount of about 4% to about 50% by weight of Part A. The one or more liquid epoxy resins may be present in an amount of about 10% to about 30% by weight of Part A. The one or more liquid epoxy resins may be present in an amount of about 8% by weight of Part A.

[0065] Epoxy resins, obtained from the reaction of epoxy with carboxyl-terminated acrylonitrile-butadiene (CTBN) liquid rubber, have traditionally been used to impart impact resistance to epoxy matrices. Numerous publications have provided information on their use to increase the fracture toughness, K1C, of ​​cured epoxy resins by creating separate precipitated rubber domains within a rigid epoxy matrix. These separate domains provide a tortuous path through the epoxy matrix for crack propagation, leading to increased fracture resistance. They may also help dissipate fracture energy by crazing, forming multiple cracks, cavitating rubber particles, debonding, and forming voids within the matrix. However, these resins typically lower the glass transition (Tg) of the adhesive, since not all the rubber phase separates from the matrix and some rubber remains reacted in the epoxy.

[0066] Epoxy functionalized molecules, such as epoxy functional urethanes, can also contribute to improved peel resistance. These molecules can help increase the affinity of the adhesive to certain substrates. These molecules can also increase the ability of the crosslinked network to absorb fracture energy by bending, flexing, or locally moving the molecular chains. These functionalized epoxy resins, and the epoxy resins resulting from the reaction products of elastomers, are commonly known as modified epoxies.

[0067] Dimer fatty acids are another group of epoxidized molecules that can improve the peel resistance of adhesives. The use of epoxidized fatty acids as epoxy tougheners and impact modifiers has increased over the last decade. These long-chain molecules, with 36 carbon atoms in the chain, impart a hydrocarbon character to the molecule and impart lubricity and flexibility to the crosslinked network. Their hydrophobicity tends to improve the adhesive's resistance to exposure to wet environments. In addition, less degradation of the adhesive matrix Tg is observed compared to adhesives containing epoxidized CTBN.

[0068] The two-part system may include one or more flexible epoxy resins. The one or more flexible epoxy resins may function to reduce the elastic modulus of the reaction product, increase the break strain, decrease the recovery time, decrease the degree of crosslink density in the reaction product, increase the impact resistance, improve adhesion, improve peel resistance, or any combination thereof. The one or more flexible epoxy resins may improve the gas entrapment capability of the two-part system, in part, by acting as a viscosity modifier or by decreasing gas permeability. The one or more flexible epoxy resins may be difunctional glycidyl ether epoxy resins, modified BPA-based epoxy resins, multifunctional epoxidized polybutadiene resins, or any combination thereof. The one or more flexible epoxy resins may have an EEW of about 260 to about 500, measured according to ASTM D1652-97. The one or more flexible epoxy resins may have a viscosity, measured according to ASTM D445, of about 700 cP to about 500,000 cP at 25° C. Examples of suitable flexible epoxy resins may include NC-514 (commercially available from Cardolite Corporation, Monmouth Junction NJ), Araldite® PY 4122 (commercially available from Huntsman Advanced Materials, Inc., Salt Lake City, UT), Poly bd® 605E (commercially available from Cray Valley, Exton, PA), or any combination thereof.

[0069] One or more flexible epoxy resins may be present in Part A. The one or more flexible epoxy resins may be present in an amount of about 10% to about 50% by weight of Part A. The one or more flexible epoxy resins may be present in an amount of about 35% to about 45% by weight of Part A. The one or more flexible epoxy resins may be present in an amount of about 39% by weight of Part A. The one or more flexible epoxy resins may include a difunctional glycidyl ether epoxy resin in an amount of about 10% to about 18% by weight of Part A, a modified BPA-based epoxy resin in an amount of about 8% to about 16% by weight of Part A, and a multifunctional epoxidized polybutadiene resin in an amount of about 8% to about 16% by weight of Part A. The one or more flexible epoxy resins may include a difunctional glycidyl ether epoxy resin in an amount of about 14% by weight of part A, a modified BPA-based epoxy resin in an amount of about 12% by weight of part A, and a multifunctional epoxidized polybutadiene resin in an amount of about 12% by weight of part A. The two-component system may include the difunctional glycidyl ether epoxy resin, the cardanol-derived difunctional epoxy, and the multifunctional epoxidized polybutadiene resin in a ratio of about 1:1:1, respectively. The two-component system may include the difunctional glycidyl ether epoxy resin, the cardanol-derived difunctional epoxy, and the multifunctional epoxidized polybutadiene resin in a ratio of about 1:0.8:0.8, respectively. The two-component system may include the difunctional glycidyl ether epoxy resin, the cardanol-derived difunctional epoxy, and the multifunctional epoxidized polybutadiene resin in a ratio of about 1:0.9:0.9, respectively.

[0070] The two-part system (adhesive) described herein may also include one or more epoxy phenol novolac resins (hereinafter "EPN"). The one or more epoxy phenol novolac resins may function to impart chemical resistance, solvent resistance, heat resistance, or any combination thereof to the reaction product. The one or more epoxy phenol novolac resins may be present as part of Part A. The one or more epoxy phenol novolac resins may have an EEW of about 165 g / eq to about 183 g / eq, measured according to ASTM D1652-97. The one or more epoxy phenol novolac resins may have an average epoxy functionality of about 2.1 to about 6.5. One of the primary functions of the EPN resin is to increase the network crosslink density through multi-functionality. This is also important for controlling the reaction rate and the ability to prevent bubbles from collapsing during and / or after the reaction process. The one or more epoxy phenolic novolac resins may have a viscosity, measured according to ASTM D445, of about 18,000 cP to about 30,000 cP at 25° C. Examples of suitable epoxy phenolic novolac resins may be those sold under the trade names Epalloy® 8250 and Epalloy® 8330, commercially available from CVC Thermoset Specialties (Moorestown, NJ).

[0071] The one or more epoxy phenol novolac resins may be present in an amount of about 30% to about 50% by weight of Part A. The one or more epoxy phenol novolac resins may be present in an amount of about 35% to about 45% by weight of the first component of Part A. The one or more epoxy phenol novolac resins may be present in an amount of about 38% to about 42% by weight of Part A. The one or more epoxy phenol novolac resins may be present in an amount of about 42% by weight of Part A. The one or more epoxy phenol novolac resins may include an epoxy phenol novolac resin with a functionality of about 3.6 present in an amount of about 2% to about 18% by weight of Part A, and an epoxy novolac resin with a functionality of about 6.5 present in an amount of about 22% to about 32% by weight of Part A. The one or more epoxy phenol novolac resins may include an about 3.6 functional epoxy phenol novolac resin present in an amount of about 15% by weight of Part A, and an about 6.5 functional epoxy novolac resin present in an amount of about 28% by weight of Part A. The two-part system may include the about 3.6 functional epoxy phenol novolac resin and the about 6.5 functional epoxy phenol novolac resin in a ratio of about 1:2 to about 1:3.

[0072] Another way to increase the fracture toughness of epoxy adhesives is by using aliphatic epoxy resins, or resins with saturated long carbon chains between the epoxy rings. Products such as Erisys® EDGE from Huntsman-CVC and cardanol-based products from Cardolite provide improved fracture resistance due to increased flexibility of their chains. Epoxidized oils, which may be aliphatic in nature, such as but not limited to soybean oil or linseed oil, may provide increased peel resistance. In addition, the long carbon chains between the functional groups create an adhesive matrix that is better able to conform to deformation with large plastic deformation zones, resulting in the absorption of some fracture energy.

[0073] The adhesive may include one or more aliphatic multifunctional epoxy resins. The one or more aliphatic multifunctional epoxy resins may function to increase the degree of crosslinking of the reaction product, increase the chemical resistance of the reaction product, or both. These resins have the ability to increase the crosslink density of the resulting reaction product while retaining or enhancing the elastomeric properties of the reaction product. The multifunctional materials may result in a less elastomeric reaction product. The one or more aliphatic multifunctional epoxy resins may include epoxidized sorbitol. The one or more aliphatic multifunctional epoxy resins may have an EEW of about 160 g / eq to about 195 g / eq, as measured according to ASTM D1652-97. The one or more aliphatic multifunctional epoxy resins may have a viscosity of about 200 cP to about 18,000 cP at 25° C., as measured according to ASTM D445. Examples of suitable aliphatic multifunctional epoxy resins may be those sold under the trade names ERISYS® GE-60 and ERISYS® GE-61, commercially available from CVC Thermoset Specialties (Moorestown, NJ), or Epoxol® 9-5, commercially available from ACS Technical Products (Griffith, IN).

[0074] The one or more aliphatic multifunctional epoxy resins may be present as part of Part A. The one or more aliphatic multifunctional epoxy resins may be present in an amount of about 5% to about 20% by weight of Part A. The one or more aliphatic multifunctional epoxy resins may be present in an amount of about 8% to about 16% by weight of Part A. The one or more aliphatic multifunctional epoxy resins may be present in an amount of about 10% to about 14% by weight of Part A. The one or more aliphatic multifunctional epoxy resins may be present in an amount of about 12% by weight of Part A.

[0075] The adhesive may include cashew nut shell liquid (hereinafter "CNSL"), which may include chemicals commonly extracted from cashew nut shell liquid (CNSL) including anacardic acid, cardol, cardanol, or any combination thereof. Preferably, the glycidyl ether of cashew nut shell liquid (CNSL) is a glycidyl ether of cardanol.

[0076] Formulations containing cardanol-derived products such as those available from Cardolite, e.g., NC-514, have also shown improved adhesion to metal substrates, especially uncleaned metal substrates that have not been surface treated or contaminated with organic materials. It is believed that the long aliphatic chains in the molecule are capable of compatibilizing or solubilizing surface contaminants such as stamping oils, protective coatings, or mold release agents, making these surfaces more accessible for bonding.

[0077] Core-shell (hereinafter "CS") particles also help to reduce or prevent fracture propagation through the adhesive. CS particles help to increase fracture toughness through the incorporation of preformed elastomeric particles with a rigid shell and a flexible core into a rigid matrix in much the same way as CTBN-added epoxies. However, because they do not react into the crosslinked network, the typical decrease in cure Tg as seen with the use of modified or flexible epoxies is smaller or nonexistent. CS particles are particularly advantageous in fast-curing adhesives because they exist as separate particles and do not require a secondary process such as reaction-induced phase separation (hereinafter "RIPS") to impart toughness to the polymer matrix. RIPS-reinforced adhesives generally benefit from slower reaction times that allow the secondary phase to form while the primary phase crosslinks. With faster reactions, there may not be time for the formation of the secondary phase. If the secondary phase does not build up, it can be expected that the Tg will decrease and become less beneficial in improving physical properties.

[0078] The adhesive may include one or more adhesives. The one or more additives may include one or more reinforcing agents, calcium carbonate, minerals, reinforcing fibers, fumed silica, platelet alumina, or any combination thereof.

[0079] As mentioned above, the adhesive may include one or more toughening agents. The one or more toughening agents may function to dissipate energy within the reaction product (i.e., increase impact resistance). The one or more toughening agents may contribute to increasing the T-peel strength. The one or more toughening agents may include thermoplastics, thermosets or thermosettables, elastomers, and the like, or any combination thereof. The one or more toughening agents may include elastomers (including elastomer-containing materials), core-shell polymers (which may include, but are not limited to, elastomers), or both.

[0080] The core-shell polymer may comprise a first polymeric material (i.e., core material) and a second polymeric material (i.e., shell material). The first polymeric material may be fully encapsulated in the second polymeric material. The core-shell polymer may comprise the first polymeric material in an amount of about 30% by weight or more, 50% by weight or more, or even 70% by weight or more. The first polymeric material, the second polymeric material, or both, may comprise one, two, three, or even four or more polymers that are combined together, reacted together (e.g., sequentially polymerized), or both, or may be part of separate or the same core-shell polymer system. Examples of suitable core-shell polymers may be those sold under the trade names Kane Ace™ MX-267 and MX-257, both of which are commercially available from Kaneka North America LLC (Pasadena, TX).

[0081] The core-shell polymer may be present in an amount of about 1% to about 25% by weight of part A, part B, or the combination of both parts A and B (e.g., if present in an amount of 10% by weight, it may be present in an amount of 5% in part A and 5% in part B). The core-shell polymer may be present in an amount of about 5% to about 20% by weight of part A, part B, or the combination of both parts A and B. The core-shell polymer may be present in an amount of about 5% by weight of part A, part B, or the combination of both parts A and B. The core-shell polymer may be present in an amount of about 17% by weight of part A, part B, or the combination of both parts A and B.

[0082] The adhesive may include one or more reactive diluents. The reactive diluents may function to reduce the overall viscosity of the two-part system to modify the flow of the two-part system during the dispensing process or on the workpiece after dispensing, and if monofunctional, to reduce the degree of crosslinking of the reaction product. If statistically greater than difunctional, the diluent may increase the crosslink density. The reactive diluent(s) may be polymeric, in which case the reactive diluent may increase the flexibility of the reaction product, or the reactive diluent(s) may be multifunctional, in which case the reactive diluent may promote increased crosslinking, impart chemical resistance to the reaction product, or both. The reactive diluent(s) may include polyglycol diglycidyl ether, trimethylolethane triglycidyl ether, or both. The reactive diluent(s) may have an EEW of about 100 g / eq to about 300 g / eq, measured according to ASTM D1652-97. The one or more reactive diluents may have a viscosity, measured according to ASTM D445, of about 10 cP to about 1000 cP at 25° C. Examples of suitable reactive diluents may be those sold under the trade names ERISYS® GE-31 and ERISYS® GE-24, commercially available from CVC Thermoset Specialties (Moorestown, NJ).

[0083] The one or more reactive diluents may be present in an amount of about 5% to about 20% by weight of Part A. The one or more reactive diluents may be present in an amount of about 8% to about 16% by weight of Part A. The one or more reactive diluents may be present in an amount of about 10% to about 14% by weight of Part A. The one or more reactive diluents may be present in an amount of about 13% by weight of Part A. The one or more reactive diluents may include a polyglycol diglycidyl ether present in an amount of about 2% to about 6% by weight of Part A, and a trimethylolethane triglycidyl ether present in an amount of about 6% to about 14% by weight of Part A. The one or more reactive diluents may include a polyglycol diglycidyl ether present in an amount of about 4% by weight of Part A, and a trimethylolethane triglycidyl ether present in an amount of about 9% by weight of Part A. The two-part system may include polyglycol diglycidyl ether and trimethylolethane triglycidyl ether in a ratio of about 1:2 to about 1:3, respectively.

[0084] The adhesive may include one or more epoxy-functional silanes or silane-modified epoxy resins. The one or more epoxy-functional silanes or silane-modified epoxy resins may function to impart improved adhesion to the reaction product, particularly adhesion to glass, metal, or both. An example of a suitable epoxy-functional silane may be that sold under the trade name Silquest™ A-187, commercially available from Momentive Performance Materials, Albany, NY. An example of a suitable silane-modified epoxy resin may be that sold under the trade name EPOKUKDO® KSR-177, commercially available from Kukdo Chemical, South Korea. Another suitable material is a silicone prepolymer having cycloaliphatic epoxide groups. An example of one such material is available under the trade name Silmer® EPC Di-50, available from Siltech Corporation, Ontario, Canada.

[0085] One or more silane-modified epoxy resins may be present in Part A. The one or more silane-modified epoxy resins may be present in an amount of about 1% to about 15% by weight of Part A. The one or more silane-modified epoxy resins may be present in an amount of about 2% to about 6% by weight of Part A. The one or more silane-modified epoxy resins may be present in an amount of about 4% by weight of Part A.

[0086] The adhesive may include one or more monomers. The one or more monomers may function to improve the adhesive properties of the reaction product, particularly to metal substrates, increase the flexibility of the reaction product, increase the impact resistance of the reaction product, or any combination thereof. The one or more monomers may be monofunctional, difunctional, or even multifunctional. The one or more monomers may be an esterification reaction product of an alcohol with acrylic or methacrylic acid. The one or more monomers may be a monofunctional acrylic monomer. Preferably, the one or more monomers may be a mixture of methacrylic acid esters and 2-(2-ethoxyethoxy)ethyl acrylate. An example of a suitable monomer may be that sold under the trade name SR 9050, commercially available from Sartomer (Exton, PA).

[0087] The adhesive may include one or more monomers in part A, part B, or both. The one or more monomers may be present in part A, part B, or the combination of both parts A and B in an amount of about 0.1% to about 26% by weight. The one or more monomers may be present in part A, part B, or the combination of both parts A and B in an amount of about 12% to about 24% by weight. The one or more monomers may be present in part A, part B, or the combination of both parts A and B in an amount of about 14% to about 22% by weight. The one or more monomers may be present in part A, part B, or the combination of both parts A and B in an amount of about 18% by weight.

[0088] The cure rate, the degree of crosslinking, or both, can be a function of the functionality of the two-part system (Part A and Part B). Higher functionality (i.e., the average number of functional groups of one or more polymerizable components) may be desirable for two-part systems having pre-polymerized components with shorter polymer lengths (i.e., lower viscosity), where the loss of structural backbone resulting from the shorter polymer is offset by a higher degree of crosslinking. Lower functionality may be desirable for two-part systems having pre-polymerized components with longer lengths (i.e., typically resulting in higher viscosity), where the presence of more structural backbone resulting from the longer polymer eliminates the need for high functionality.

[0089] The functionality of Part B may be reduced, at least in part, by reaction of metal carbonates in Part A with phosphoric acid and phosphate esters, resulting in a reduced functionality of Part B. Part A may include components with increased functionality to offset the reduced functionality of Part B. Part A may be formulated with increased functionality by using reactive components with functionality greater than 2.

[0090] As described in US Patent No. 6,730,713, when metal carbonates are exposed to phosphoric acid and / or esters of phosphoric acid in the presence of epoxy resins, bubbles can be generated through the release of carbon dioxide during the curing process. A foamed adhesive or a cellular structure within the adhesive can be beneficial for improving peel resistance. Cohesive failure within a foamed adhesive is generally easily achieved due to weakening of the polymer bulk by pore formation. Once a cohesive failure mode is initiated, it often remains cohesive, in part due to the reduction in moment arm length and change in load angle, resulting in slower crack progression. Cohesive failure drives the failure path through the adhesive as opposed to at the adhesive-substrate interface, resulting in higher resistance forces, shorter crack propagation distances, and, as a result, generally higher peel strengths.

[0091] The calcium carbonate and acid reaction neutralizes a portion of the acid. Changing the acid equivalent of the mixed product in this manner reduces the crosslink density of the adhesive and changes the mechanical properties. Calcium carbonate or another metal carbonate can be added directly to the hardenable mixture to change the acidity of the mixed composition. With a fixed volume ratio between the resin and the hardener, neutralizing the acid in this manner allows for a change between the acid and epoxy equivalent in the mixed adhesive.

[0092] The adhesive may include one or more metal carbonates. The one or more metal carbonates may function to generate gas in the presence of acid, act as a filler, control the initiation or overall extent of the foaming (e.g., expansion) process, or both. The one or more metal carbonates may be metal carbonates or metal bicarbonates. Examples of suitable fillers include calcium carbonate, nickel carbonate, barium carbonate, sodium bicarbonate, and potassium bicarbonate. Preferably, the one or more metal carbonates may include calcium carbonate. The particle size of the metal carbonate, metal bicarbonate, or both may control the expansion and hardening of the two-part system, where the total surface area of ​​the metal carbonate, metal bicarbonate, or both available for reaction with the acid is a function of both the particle size of the metal carbonate, metal bicarbonate, or both and the amount present in the two-part system.

[0093] The calcium carbonate may be present as one or more calcium carbonate fillers. The one or more calcium carbonate fillers may have a median particle size of about 1 to about 50 microns. The calcium carbonate may be a medium fine particle size. For example, the medium fine calcium carbonate may have a median particle size of about 22 microns. An example of a suitable medium fine calcium carbonate may be Hubercarb® Q200, commercially available from Huber Engineered Materials, Atlanta, GA. The calcium carbonate may be a fine particle size. For example, the fine calcium carbonate may have a median particle size of about 4 microns. An example of a suitable fine calcium carbonate may be Hubercarb® Q4, commercially available from Huber Engineered Materials, Atlanta, GA. The calcium carbonate may be an ultrafine particle size. For example, the ultrafine calcium carbonate may have a median particle size of about 1 micron. An example of a suitable ultrafine calcium carbonate may be Hubercarb® Q2, commercially available from Huber Engineered Materials, Atlanta, GA. The two-part system may include medium fine calcium carbonate, fine calcium carbonate, extra fine calcium carbonate, or any combination thereof.

[0094] The calcium carbonate may be present in an amount of about 1% to about 25% by weight of the A solution. The calcium carbonate may be present in an amount of about 4% to about 18% by weight of the A solution. The calcium carbonate may be present in an amount of about 8% to about 12% by weight of the A solution. The calcium carbonate may be present in an amount of about 20% by weight of the A solution. The calcium carbonate may include both fine calcium carbonate present in an amount of about 4% to about 8% by weight of the A solution, and medium fine calcium carbonate present in an amount of about 13% to about 18% by weight of the A solution. The calcium carbonate may include both fine calcium carbonate present in an amount of about 6% by weight of the A solution, and medium fine calcium carbonate present in an amount of about 15% by weight of the A solution. The calcium carbonate may include both fine calcium carbonate present in an amount of about 5% by weight of the A solution, and medium fine calcium carbonate present in an amount of about 5% by weight of the A solution. The ratio of medium fine calcium carbonate to fine calcium carbonate may be about 3:1 to about 1:3. The ratio of medium fine calcium carbonate to fine calcium carbonate may be about 1:1.

[0095] The calcium carbonate may include a coating. The coating may be any material that decomposes during the activation process, the expansion process, or both, so that the expansion is delayed, slowed, or both. The coating may be a wax, a fatty acid, or a combination thereof.

[0096] The adhesive may include one or more minerals. The one or more minerals (i.e., "mineral reinforcement") may function to structurally reinforce the reaction product. The one or more minerals may improve the tensile strength, flexural strength, or both, of the reaction product. The one or more minerals may be any suitable silicate mineral, including, but not limited to, inosilicates (e.g., wollastonite) and phyllosilicates (e.g., kaolinite, vermiculite, talc, muscovite, etc.). The characteristic external shape of the individual crystals or groups of crystals of the one or more minerals may be needle-like or acicular. The median particle size of the one or more minerals may be from about 10 microns to about 20 microns. The median particle size may be from about 12 microns to about 18 microns.

[0097] The adhesive may include one or more reinforcing fibers. The reinforcing fibers may function to structurally reinforce the reaction product. The reinforcing fibers may improve the tensile strength, flexural strength, or both, of the reaction product. The reinforcing fibers may be present in part A, part B, or both. The reinforcing fibers may be homogeneously dispersed within part A, part B, or both. The reinforcing fibers may include polymeric fibers, glass fibers (i.e., fiberglass), or both. The polymeric fibers may include nylon, polyamide, polyester, polypropylene, polyethylene, polytetrafluoroethylene, aramid fibers (e.g., Kevlar®), and the like, or any combination thereof. The glass fibers may include alumino-borosilicate glass ("E-glass"), alkali-lime glass ("A-glass" or "C-glass"), electrical / chemical resistant glass ("E-CR glass"), borosilicate glass ("D-glass"), alumino-silicate glass ("R-glass" or "S-glass"), or any combination thereof. The reinforcing fibers may be chopped fibers. The reinforcing fibers may be chopped to lengths of about 0.1 cm or more, about 0.3 cm or more, or even about 0.6 cm or more. The reinforcing fibers may be chopped to lengths of about 2.0 cm or less, about 1.5 cm or less, or even about 1.0 cm or less. An example of a suitable fiberglass may be chopped strand commercially available from Jushi USA (Columbia, SC).

[0098] The reinforcing fibers may be present in an amount of about 0.01% to about 3% by weight of Part A, Part B, or a combination of both Parts A and B. The reinforcing fibers may be present in an amount of about 0.1% to about 1% by weight of Part A, Part B, or a combination of both Parts A and B. The reinforcing fibers may be present in an amount of about 0.2% by weight of Part A, Part B, or a combination of both Parts A and B. The two-part system may include one or more thixotropes to control viscosity.

[0099] The two-part system may include a hydrophobic silica. The hydrophobic silica may function to control viscosity (e.g., thicken), control thixotropy, boost hydrophobicity, or a combination thereof. The hydrophobic silica may be a fumed silica. The hydrophobic silica may be surface-treated. For example, the hydrophobic silica may be a fumed silica surface-treated with polydimethylsiloxane (hereinafter "PDMS") or hexamethyldisilazane (hereinafter "HMDZ"). The hydrophobic silica may be present as part of part A, part B, or both. Examples of suitable hydrophobic silicas may be those sold under the trade name AEROSIL® R 202, commercially available from Evonik Corporation, Parsippany, NJ, and those sold under the trade names CAB-O-SIL® TS-530 and TS-720, commercially available from Cabot Corporation, Boston, MA.

[0100] The hydrophobic silica may be present in an amount of about 0.25% to about 6% by weight of the A liquid, the B liquid, or the combination of both A and B liquids. The hydrophobic silica may be present in an amount of about 0.5% to about 4% by weight of the A liquid, the B liquid, or the combination of both A and B liquids. The hydrophobic silica may be present in an amount of about 1% to about 2% by weight of the A liquid, the B liquid, or the combination of both A and B liquids. The hydrophobic silica may be present in an amount of about 0.5% to about 2% by weight of the A liquid. The hydrophobic silica may be present in an amount of about 3% to about 5% by weight of the B liquid. The ratio of hydrophobic silica in the B liquid to the A liquid may be about 1:6 to about 6:1. The ratio of hydrophobic silica in the B liquid to the A liquid may be about 1:4. The ratio of hydrophobic silica in the B liquid to the A liquid may be about 1:2 to about 2:1.

[0101] The two-part system may include platelet alumina. The platelet alumina may function to impart hardness, resistance to thermal shock, resistance to mechanical shock, high heat capacity, high electrical resistance, or any combination thereof to the reaction product. The platelet alumina may be present in part A, part B, or both. The platelet alumina may be alpha alumina that has been converted to its corundum form (i.e., crystalline aluminum oxide) and sintered, or may be provided as graded granules or powder. The platelet alumina may be graded (i.e., separated by size) from about 44 microns to about 4760 microns. The platelet alumina may be graded to about 44 microns.

[0102] The tabular alumina may be present in an amount of about 0.1% to about 15% by weight of Part A, Part B, or a combination of both Parts A and B. The tabular alumina may be present in an amount of about 4% to about 12% by weight of Part A, Part B, or a combination of both Parts A and B. The tabular alumina may be present in an amount of about 5% by weight of Part A. The tabular alumina may be present in an amount of about 10% by weight of Part A.

[0103] The adhesive may include one or more functional additives to improve one or more various properties of the composition. Examples of suitable functional additives may include antioxidants, antiozonants, UV absorbers, antistatic agents, colorants, coupling agents, curing agents, flame retardants, foaming agents, heat stabilizers, impact modifiers, lubricants, plasticizers, preservatives, processing aids, stabilizers, and the like, and any combination thereof.

[0104] The viscosity of part A, part B, or both may be high enough at about 23° C. to preclude undesired flow of the two-part system into areas adjacent to the dispensed beads when the two-part system is dispensed onto a workpiece, or to control flow (i.e., allow a desired amount of flow) into areas adjacent to the dispensed beads when the two-part system is dispensed. The viscosity of part A, part B, or both required to preclude undesired flow or control flow may depend on the size of the dispensed beads. For example, the denser the beads of the dispensed two-part system, the higher the viscosity required to preclude unintended flow or control flow. The viscosity of part A at 23° C. may be from about 5,000 cP to about 50,000 cP, or even from about 35,000 cP to about 45,000 cP at very low shear rates that approximate sag conditions. The viscosity of parts A and B at 23° C. may be from about 250,000 cP to about 400,000 cP. The viscosity of solution A at 10° C. may be about 280,000 cP to about 350,000 cP, or even about 300,000 cP to about 325,000 cP. The viscosity of solution B at 23° C. may be about 2,500 cP to about 50,000 cP, or even about 35,000 cP to about 45,000 cP. The viscosity of solution B at 10° C. may be about 130,000 cP to about 220,000 cP, or even about 175,000 cP to about 195,000 cP.

[0105] The adhesive may expand, upon mixing of parts A and B, by more than about 50%, more than about 100%, more than about 200%, less than about 800%, less than about 700%, or even less than about 600% of the original volume of the two-part system. The two-part system may expand from about 400% to about 500% of the original volume of the two-part system. The two-part system may expand about 100% of the original volume of the two-part system. The adhesive may not substantially expand.

[0106] The adhesive may be free of a curing agent (i.e., a conventional curing agent), a cure accelerator, or both. Typical curing agents include Lewis bases (i.e., anionic catalysts), Lewis acids (i.e., cationic catalysts), UV catalysts, amines, anhydrides, phenols, thiols, or any combination thereof. In place of the aforementioned curing agents, the two-part system may cure upon a polymerization reaction between a phosphate ester and an epoxide group, a hydroxyl group, or both, catalyzed by phosphoric acid. The two-part system may be cured and expanded by a chemical interaction between a phosphate ester and a metal carbonate. By utilizing the curing and expansion system of the present disclosure, the complexity of the formulation may be reduced by reducing the number of total components (i.e., curing agents, cure accelerators, and blowing agents), however, it has been found that optimizing to achieve the desired expansion and cure time becomes more difficult.

[0107] The two-part systems may be mixed together in a ratio of Part A to Part B of 1:4 to 4:1. The two-part systems may be mixed together in a ratio of Part A to Part B of 1:2 to 2:1. The two-part systems may be mixed together in a ratio of Part A to Part B of 1:1. The two-part systems may be mixed together in a ratio of Part A to Part B of 2:1.

[0108] The adhesive may cure and / or expand before or after complete assembly of the workpieces to which the adhesive is applied. For example, the adhesive may be dispensed onto a first workpiece, cured and / or expanded, and then a second workpiece complementary to the first workpiece may be applied onto the first workpiece. As another example, the adhesive may be dispensed onto a first workpiece, a second workpiece complementary to the first workpiece may be applied onto the first workpiece, and then the two-part system may cure and / or expand. The adhesive that cures and / or expands after complete assembly of the workpieces may expand to fill the space between the first and second workpieces. The first workpiece, the second workpiece, or both, may include a groove into which the adhesive is dispensed, expands, or both. The two-component material may be dispensed into a cavity.

[0109] Table 1 provides test results for a typical commercially available 5 minute epoxy adhesive. T-peel resistance is measured as the average force required to separate bonded substrates from each other at 180° divided by the bond width and is often given in units of Newtons per millimeter (N / mm) or pounds per inch (lb / in) according to ASTM D1876. T-peel samples are tested at 100 mm / min. Lap shear samples tested according to EN2243-1 are tested at 50 mm / min. Tensile samples are tested at 10 mm / min according to ISO527. Tg values ​​were taken from the peak of G prime as opposed to tan delta as measured by DMA. This value indicates the onset of change in material properties.

[0110] [Table 1]

[0111] The lap shear results are very good for the E-coated steel specimens of JB Weld, but drop off significantly for the galvanized and aluminum substrates. The lap shear results for Devcon® 5 Minutes, Gorilla glue 5 Minutes, and Scotch Weld™ are lower than would be expected for a structural adhesive.

[0112] According to the test standard, peel strength is calculated from the average force per unit width after the first 10 mm of displacement from the initial peak force. Brittle T-peel bonds represent a fast and abrupt debonding of the substrates before or shortly after this displacement can be reached. The failure mode is represented by percent cohesive failure (CF), which is represented by approximately equal amounts of adhesive remaining bonded to each substrate after the test. Superficial cohesive failure (TCF) is classified when the majority of the adhesive remains on one substrate, but a film or thin coating of adhesive remains on the second substrate. Adhesive failure (AF) is defined as when the majority of the adhesive remains bonded to one substrate and no adhesive remains on the second substrate.

[0113] The following examples describe the use of phosphoric acid and or phosphate esters and other acidic components as primary curing agents with mixtures containing epoxide functional materials including bisphenol-A, bisphenol-F, aliphatic and elastomer modified epoxies as primary resins to produce two-component adhesives that cure at ambient temperatures, particularly with some epoxide functionality characterized by improved T-peel resistance.

[0114] [Table 2]

[0115] Table 2 includes examples of formulations that vary the epoxy-containing A-part and a common hardener B-part. While the examples contain many of the ingredients described herein and are considered within the scope of the present teachings, Example 1 shows some superior physical properties when compared to Examples 2-6. In Example 1, we observe peel values ​​of at least 5 N / mm for cohesive or thin cohesive failure morphologies on a variety of substrates. Example 2, which does not contain calcium carbonate, gives reduced peel values, even though the failure morphology for some substrates shows adhesive remaining. On electrocoated steel substrates, the adhesive breaks before a measurable peel is obtained, indicating a brittle bond. Stick / slip failure morphology indicates peel performance with highly variable regions of bond strength.

[0116] Calcium carbonate reduces the cohesive strength within the resin matrix, which can result in failure within the adhesive rather than at the adhesive-substrate interface. The reaction of calcium carbonate with the acidic hardener consumes some of the acidic reactive sites, possibly resulting in less crosslinking throughout the system. This reaction also most likely retards the crosslinking reaction by causing most of the acidic hydrogen atoms to react first, producing carbon dioxide gas. The slower crosslinking rate allows for a longer wetting time of the adhesive to the substrate and the creation of a cellular structure within the adhesive, both of which tend to improve peel resistance.

[0117] In Example 3, the multifunctional aliphatic resin is removed in proportion to the removal of the component, with an increased percentage of all components compared to Example 1. This results in an increase in lap shear values, but a decrease in peel values, and a decrease in tensile elongation, while the tensile modulus increases. The overall strength of the system is reduced in Example 4 compared to Example 1 when one of the Bis-A epoxy resins is removed. A decrease in tensile properties, as well as a decrease in lap shear and peel values, is observed. In Example 5, the system shows a more brittle peel response, as demonstrated by the decrease in all peel measurements. In this batch, the multifunctional epoxidized linseed oil is replaced by a multifunctional epoxidized sorbitol. In Example 6 compared to Example 1, the Bis-A epoxy resin is replaced by an epoxidized polypropylene glycol. Comparing Example 6 to Example 1, the tensile modulus is reduced and the elongation is significantly increased. A general decrease in adhesive strength and a brittle behavior of the peel on electrocoated steel is also measured. Comparing Example 6 with Example 4, the tensile modulus also decreases with increasing elongation when epoxidized polypropylene glycol is added to the example. Again, the peel performance to electrocoated steel decreases, however, a slight increase in lap shear and peel on other substrates is observed.

[0118] [Table 3]

[0119] In Examples 7 and 8, the effect of epoxidized linseed oil on adhesive properties is evaluated. In Example 7, all of the phenolic novolac resin is replaced by epoxidized linseed oil. However, this increases the overall crosslink density of the system due to the resin having higher molecular mobility than the novolac. The failure mode of the peel shifts to adhesive failure and generally results in lower strength. As shown in Example 8 compared to Example 1, a 20% increase in epoxidized linseed oil significantly increases the lap shear value, but the peel results decrease. However, the failure mode remains cohesive at this level compared to Example 7.

[0120] Example 9 represents another embodiment of the present teachings. As in the previous examples, phosphoric acid and esters of phosphoric acid are used to crosslink mixtures of aromatic, aliphatic, and impact-modified epoxies combined with CS particles to produce adhesives with improved peel resistance. Example 9 demonstrates different ratios of phosphoric acid to esterified acid used to produce these types of adhesives. These ratios are varied in part by the use of carboxylic acid-terminated polymers.

[0121] [Table 4]

[0122] In Examples 10-12 of Table 4, the importance of ingredients is evaluated by systematically removing them. In Examples 13 and 14, the effect of polymeric fibers on the performance of the adhesive is evaluated. In Example 10, CS is removed compared to Example 1, while the other ingredient percentages remain in the same relative ratio to each other. The Kane Ace product is a dispersion of 37% CS in liquid epoxy resin, with YD-128 added to the formulation to make up for the loss of resin. Without the CS particles, the adhesive is more brittle. A higher tensile modulus is measured along with an increase in lap shear and a significant decrease in peel performance. Lower cohesive failure is also recorded.

[0123] Compared to Example 1, all aliphatic epoxy resins are removed from Example 11. A significant increase in tensile modulus and a decrease in tensile elongation are measured. Both lap shear and T-peel adhesion performance also decrease significantly for all substrates. In Example 12, compared to Example 1, the epoxidized urethane resin is removed. All measured properties are lower.

[0124] The fumed silica in the resin solution and the Garamite® in the hardener solution are removed from Example 12 and largely replaced by polymeric fibers to produce Example 13. Increased lap shear and peel performance is measured, especially on galvanized steel. Example 14 was produced by adding fibers to both the A and B solutions of Example 1. In this example, the lap shear values ​​remain similar, but both the tensile and T-peel performance decrease.

[0125] The present teachings provide a method that may include providing a two-part system, the two-part system including part A (i.e., a first component) and part B (i.e., a second component). Part A includes one or more epoxy resins, and part B includes one or more phosphate esters and optionally phosphoric acid. Part A and part B can be mixed to form a curable composition. The method may include curing the curable composition at a temperature less than 50° C., thereby forming a reaction product. The method may include mixing the first component and the second component to form a reaction product. The method may include, in the curing step, curing the reaction product of the first component and the second component at a temperature less than 50° C. The method may use part A including one or more epoxy resins, calcium carbonate, or both. The method may use part B including one or more phosphate esters, phosphoric acid, or both. The method may use part A, part B, or both with one or more additives.

[0126] As used herein, unless otherwise stated, the teachings contemplate that any member of a genus (list) may be excluded from the genus and / or any member of a Markush group may be excluded from the group.

[0127] Unless otherwise stated, any numerical value recited herein includes all values ​​from the lower value to the upper value in increments of one unit, provided that there is at least a two unit separation between any lower value and any upper value. As an example, when an amount of an ingredient, a property or a value of a process variable, such as temperature, pressure, time, etc., is stated to be, for example, 1 to 90, preferably 20 to 80, more preferably 30 to 70, it is intended that intermediate range values ​​(e.g., 15 to 85, 22 to 68, 43 to 51, 30 to 32, etc.) are within the scope of the teachings herein. Similarly, individual intermediate values ​​are also within the scope of the teachings. For values ​​that are less than one, one unit is considered to be 0.0001, 0.001, 0.01, or 0.1, as appropriate. These are merely examples of what is specifically intended, and all possible combinations of numerical values ​​between the lowest and highest values ​​specified should be considered to be expressly recited in this application in a similar manner. As will be appreciated, teachings of amounts expressed herein as "parts by weight" also contemplate the same ranges expressed as weight percent. Thus, expressions of a range in "at least 'x' parts by weight of the resulting composition" also contemplate teachings of the same recited amount range of "x" weight percent of the resulting composition.

[0128] Unless otherwise stated, all ranges include the endpoints and all numbers between the endpoints. The use of "about" or "approximately" in connection with a range applies to both ends of the range. Thus, "about 20 to 30" is intended to encompass "about 20 to about 30," including at least the specified endpoints. Unless otherwise stated, teachings of the term "about" or "approximately" in combination with a numerical quantity encompass the recited amount and teachings as approximations of the recited amount. For example, a teaching of "about 100" encompasses a teaching of 100.

[0129] The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. The term "consisting essentially of" describing a combination includes the specified elements, ingredients, components, or steps, and other elements, ingredients, components, or steps that do not materially affect the basic and novel properties of the combination. The use of the terms "comprising" or "including" herein to describe a combination of elements, ingredients, components, or steps also contemplates embodiments that consist of or consist essentially of the elements, ingredients, components, or steps.

[0130] Multiple elements, ingredients, components or steps may be provided by a single integrated element, ingredient, component or step. Alternatively, a single integrated element, ingredient, component or step may be divided into separate elements, ingredients, components or steps. Disclosure of "a" or "one" describing an element, ingredient, component or step is not intended to exclude additional elements, ingredients, components or steps.

[0131] It should be understood that the above description is illustrative and not intended to be limiting. Many embodiments and many applications other than the examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present invention should be determined without reference to the above description, but instead with reference to the appended claims, together with the full scope of equivalents to which such claims are entitled. The disclosures of all papers and references, including patent applications and publications, are incorporated by reference for all purposes. The omission in the following claims of any aspect of the subject matter disclosed herein should not be considered as a disclaimer of such subject matter, nor as the inventors consider such subject matter to be not part of the inventive subject matter of this disclosure.

Claims

1. In a formulation of a curable adhesive, Part A comprises one or more epoxy resins, It contains part B, which contains an acidic phosphorus component. The adhesive comprises one or more of the following: calcium carbonate, minerals, reinforcing fibers, hydrophobic silica, or any combination thereof. The cured adhesive provides an assembly having a lap shear of at least about 15 MPa, as measured according to EN2243-1. compound.

2. In a formulation of a curable adhesive, Part A comprises one or more epoxy resins, It contains part B, which contains an acidic phosphorus component. The cured adhesive has a T-shaped peel of at least about 2.5 N / mm as measured according to ASTM D1876. The cured adhesive provides an assembly having a lap shear of at least about 15 MPa, as measured according to EN2243-1. compound.

3. The formulation according to claim 1 or 2, wherein the acidic phosphorus component comprises one or more phosphate esters, phosphoric acid, polyphosphate, phosphorus pentoxide, or any combination thereof.

4. The formulation according to claim 3, wherein one or more phosphate esters include a first phosphate ester, a second phosphate ester, a third phosphate ester, or any combination thereof.

5. One or more phosphate esters, independently of each other, - alcohol, - Epoxide group of phosphate ester precursor (i.e., component that has not yet reacted with phosphoric acid), - Mono-epoxide functional molecules, - Glycidyl ether of cashew nut shell liquid (CNSL), - Phenylglycidyl ether, - 2-ethylhexylglycidyl ether, - Epoxy-modified para-tert-butylphenol The formulation according to claim 3, which is a reaction product of the following.

6. The formulation according to claim 3, wherein one or more phosphate esters are present in an amount of about 0.1% to about 30% by weight of solution B, preferably about 10% to about 14% by weight of solution B.

7. The formulation according to claim 3, wherein at least one phosphate ester is present in an amount of about 10% to about 60% by weight of solution B, preferably about 25% to about 35% by weight of solution B, and more preferably about 28% to about 32% by weight of solution B.

8. The formulation according to claim 3, wherein at least one phosphate ester is present in an amount of about 5% to about 40% by weight of solution B, preferably about 15% to about 25% by weight of solution B, and more preferably about 18% to about 22% by weight of solution B.

9. The formulation according to claim 3, wherein at least one phosphate ester is present in an amount of about 10% to about 65% by weight, preferably about 35% to about 45% by weight, of solution B.

10. The composition according to claim 1 or 2, wherein part B comprises one or more nonphosphorus-containing acids or derivatives, one or more acid anhydrides, one or more monomers, or any combination thereof.

11. The formulation according to claim 1 or 2, wherein one or more liquid epoxy resins are independently reaction products of epichlorohydrin and bisphenol, preferably bisphenol A, bisphenol F, or both.

12. One or more liquid epoxy resins, - Measured according to ASTM D1652-97, approximately 100 g / equivalent to approximately 1000 g / equivalent of epoxide. - Approximately 20 to 25 percent epoxide, and / or - Viscosity measured according to ASTM D445, approximately 10 cP to approximately 100,000 cP at 25°C. The compound according to claim 11, having the following characteristics.

13. The formulation according to claim 11, wherein one or more liquid epoxy resins are present in an amount of about 4% to about 50% by weight of liquid A. One or more liquid epoxy resins may be present in an amount of approximately 10% to approximately 30% by weight of solution A. One or more liquid epoxy resins may be present in an amount of approximately 8% by weight of solution A.

14. The formulation according to claim 1 or 2, wherein one or more epoxy resins preferably comprises one or more flexible epoxy resins selected independently from a bifunctional glycidyl ether epoxy resin, a modified BPA-based epoxy resin, a polyfunctional epoxidized polybutadiene resin, or any combination thereof.

15. One or more flexible epoxy resins, independently of each other, - Measured according to ASTM D1652-97, approximately 260 to approximately 500 epoxide equivalents, and / or - Viscosity measured according to ASTM D445, approximately 700 cP to approximately 500,000 cP at 25°C. The compound according to claim 14, having the following characteristics.

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