KR102706217B1 - A one-component epoxy adhesive composition containing a polyfunctional amine curing agent - Google Patents

Abstract

The one-component epoxy adhesive composition of the present invention comprises an epoxy resin, a novel multifunctional amine curing agent, an amine curing agent, a toughening agent, and a curing accelerator, and has excellent curing behavior, and a cured product cured by the composition has excellent curing density, maintains excellent heat resistance and excellent tensile strength, and can have excellent impact strength and flexural strength, and can have remarkable shear strength with respect to different materials.

Description

{A one-component epoxy adhesive composition containing a polyfunctional amine curing agent}

The present invention provides a one-component epoxy composition containing a multifunctional amine curing agent and an adhesive article containing the same.

Epoxy resins have been used in various industrial fields such as adhesives, paints, electrical and electronic materials, and civil engineering and construction materials due to their excellent mechanical properties, solvent resistance, and electrical properties.

The above epoxy resin is mainly used as a one-component or two-component epoxy adhesive composition by mixing it with a hardener, and the properties of the cured product are greatly affected by the epoxy resin and hardener included.

Conventional epoxy adhesive compositions generally use bisphenol-based epoxy resins that have excellent heat resistance, excellent mechanical properties, and excellent electrical properties. However, epoxy adhesive compositions containing bisphenol-based epoxy resins have the disadvantage of high brittleness, and their adhesive strength for dissimilar materials is still inadequate.

The most effective way to solve the problems of the above epoxy adhesive composition and to obtain the properties required in various technical fields is to modify the structure of the included epoxy resin. However, since the range of properties that change in the curing behavior, mechanical properties, heat resistance, and electrical properties of the epoxy adhesive composition is large, there is a technical limitation in maintaining the excellent properties of the conventional epoxy resin and simultaneously obtaining the targeted properties.

In this way, the epoxy adhesive may maintain its original excellent properties, and it may be desirable to use a new hardener to increase the targeted properties.

However, the above epoxy adhesive composition does not significantly improve the target properties by including a new hardener, and in particular, it still has a low adhesive strength for different materials.

Therefore, there is a need for a new epoxy adhesive composition that has excellent adhesion to dissimilar materials and excellent mechanical properties, heat resistance, and electrical properties of the original epoxy adhesive composition.

Korean Patent Publication No. 10-1847140 (2018.04.03)

The purpose of the present invention is to provide a one-component epoxy adhesive having excellent adhesive strength for different types of materials.

Another object of the present invention is to provide a one-component epoxy adhesive having a curing process superior to that of conventional epoxy adhesive compositions.

Another object of the present invention is to provide a one-component epoxy adhesive composition which maintains the initial static strength and heat resistance of a conventional epoxy adhesive composition and has excellent dynamic strength.

Another object of the present invention is to provide an adhesive article having a low curling rate, manufactured by including the one-component epoxy adhesive composition.

The one-component epoxy adhesive composition of the present invention comprises an epoxy resin, an amine curing agent, a curing accelerator, a toughening agent, and a multifunctional amine curing agent represented by the following chemical formula 1.

[Chemical Formula 1]

(In the above chemical formula 1, R ₁ , R ₂ and R ₃ are each independently hydrogen or C ₁ -C ₆ alkyl, j, k, l, m, n and o are each independently an integer from 1 to 6, and Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ are each independently a straight-chain or branched-chain C ₁ -C ₁₂ alkylene group or a divalent aromatic organic group.)

As an example, in the chemical formula 1, the divalent aromatic organic groups of Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ may be represented by the following chemical formula 2 or chemical formula 3.

[Chemical formula 2]

(In the above chemical formula 2, R ₄ is independently C ₁ -C ₆ alkyl or C ₁ -C ₆ alkoxy, and p is an integer from 0 to 4.)

[Chemical Formula 3]

(In the above chemical formula 3, L is a C ₁ -C ₆ alkylene group, *-C(=O)-*, *-O-*, *-S-* or *-S(=O) ₂ -*, R ₅ and R ₆ are each independently a C ₁ -C ₆ alkyl or a C ₁ -C ₆ alkoxy, and q and r are each independently an integer from 0 to 4.)

As an embodiment, in the chemical formula 1, R ₁ , R ₂ and R ₃ are each independently hydrogen, methyl or ethyl, j, k, l, m, n and o are each independently an integer from 1 to 3, and Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ may each be a straight-chain C ₁ -C ₃ alkylene group or a group represented by the following chemical formula 3.

[Chemical Formula 3]

(In the above chemical formula 3, L is a C ₁ -C ₆ alkylene group, *-C(=O)-*, *-O-*, *-S-* or *-S(=O) ₂ -*, R ₅ and R ₆ are each independently a C ₁ -C ₆ alkyl or a C ₁ -C ₆ alkoxy, and q and r are each independently an integer from 0 to 4.)

As an embodiment, in the chemical formula 3, L is a C ₁ -C ₆ alkylene group, *-C(=O)-* or *-S(=O) ₂ -*, R ₅ and R ₆ are each independently methyl or ethyl, and q and r can each independently be an integer from 0 to 1.

As an embodiment, the multifunctional amine curing agent may be represented by the following chemical formula 4 or chemical formula 5.

[Chemical Formula 4]

[Chemical Formula 5]

As an embodiment, the epoxy resin may be a bisphenol-based epoxy resin.

As an embodiment, the one-component epoxy adhesive composition may contain 1 to 10 parts by weight of a multifunctional amine curing agent per 100 parts by weight of the epoxy resin.

As an embodiment, the one-component epoxy adhesive composition may contain 5 to 15 parts by weight of an amine curing agent per 100 parts by weight of an epoxy resin.

As an embodiment, the amine curing agent may be one or more selected from an aliphatic amine curing agent, an alicyclic amine curing agent, an aryl amine curing agent, and an acid anhydride amine curing agent.

As an embodiment, the toughening agent may be a mixture of a urethane-based toughening agent and a core-shell type toughening agent.

As an embodiment, the one-component epoxy adhesive composition may contain 50 to 150 parts by weight of a toughening agent per 100 parts by weight of an epoxy resin.

As an embodiment, the curing accelerator may be 3-phenyl-1,1-dimethylurea.

As an embodiment, the one-component epoxy adhesive composition may contain 1 to 5 parts by weight of a curing accelerator per 100 parts by weight of the epoxy resin.

As an embodiment, the one-component epoxy adhesive composition may further include 1 to 10 parts by weight of a filler per 100 parts by weight of the epoxy resin.

The present invention provides a cured product obtained by curing the one-component epoxy adhesive composition.

The present invention provides an adhesive article comprising a first substrate layer, a second substrate layer bonded to the first substrate layer, and an adhesive layer formed by curing the one-component epoxy adhesive composition between the first substrate layer and the second substrate layer.

As an embodiment, the first substrate layer and the second substrate layer may be independently one or more selected from metal, steel plate, wood, film, tile, plastic, glass, resin, ceramic, concrete, carbon material, fiber, and the like.

As an example embodiment, the adhesive may have a shear strength of 5 to 20 MPa as measured by ASTM D1002.

The one-component epoxy adhesive composition of the present invention can have excellent adhesive strength for different materials, with a shear strength of 5 to 20 MPa as measured by ASTM D1002, so that an adhesive product manufactured including the composition can be less likely to peel off due to external impact.

The one-component epoxy adhesive composition of the present invention provides excellent curing density, thereby enabling a more excellent curing process.

The one-component epoxy adhesive composition of the present invention can have excellent tensile strength and heat resistance.

Therefore, the one-component epoxy adhesive composition of the present invention has excellent static strength, excellent heat resistance, and excellent electrical properties of an epoxy resin, and can have excellent dynamic strength. In addition, when bonding different materials, it has excellent shear strength, and thus can be more usefully used as an adhesive material in various industries.

Hereinafter, the single-component epoxy adhesive composition of the present invention will be described in detail. In this case, if there is no other definition for the technical and scientific terms used, they have the meaning commonly understood by those of ordinary skill in the art to which this invention belongs, and in the following description, explanations of well-known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

As used herein, the singular form may be intended to include the plural form as well, unless the context clearly indicates otherwise.

In addition, the numerical range used in this specification includes the lower limit and the upper limit and all values within that range, the increments logically derived from the shape and width of the defined range, all values that are double-defined, and all possible combinations of the upper and lower limits of the numerical range defined in different shapes. Unless otherwise specifically defined in the specification of the present invention, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

The term "comprises," as used herein, is an open-ended description having the same meaning as "comprises," "contains," "has," or "characterized by," and does not exclude additional elements, materials, or processes not listed herein.

In this specification, the term "C ₁ -C _n " may be a term meaning "having 1 to n carbon atoms.

As used herein, the term “divalent aromatic organic group” may be an aromatic organic group containing two radicals.

Conventional epoxy adhesive compositions can have excellent tensile strength, heat resistance, and electrical properties, but because they are brittle, they have been difficult to use as adhesive materials in technical fields that require excellent static strength, such as impact strength, flexural strength, and shear strength.

In order to implement another property of the above conventional epoxy adhesive composition, there is an advantage that including an epoxy resin capable of having excellent static strength can have the best effect, but there is a disadvantage that the tensile strength, heat resistance, and electrical characteristics are greatly reduced. Therefore, it may be desirable for the conventional epoxy adhesive composition to maintain the original excellent properties of the epoxy adhesive composition and include a curing agent having a new effect when the target property is to be improved.

The inventors of the present invention have conducted in-depth research to solve the problems of the above epoxy adhesive composition, and as a result, have discovered a one-component epoxy adhesive composition that includes a novel multifunctional amine curing agent and has excellent tensile strength, excellent flexural strength and excellent impact strength, as well as excellent shear strength for different materials, thereby completing the present invention.

Hereinafter, the one-component epoxy adhesive composition of the present invention will be described.

The one-component epoxy adhesive composition of the present invention comprises an epoxy resin, an amine curing agent, a curing accelerator, a toughening agent, and a multifunctional amine curing agent represented by the following chemical formula 1.

[Chemical Formula 1]

(In the above chemical formula 1, R ₁ , R ₂ and R ₃ are each independently hydrogen or C ₁ -C ₆ alkyl, j, k, l, m, n and o are each independently an integer from 1 to 6, and Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ are each independently a straight-chain or branched-chain C ₁ -C ₁₂ alkylene group or a divalent aromatic organic group.)

The above multifunctional amine curing agent has six amine groups, and a one-component epoxy adhesive composition containing the same can have excellent curing behavior and excellent curing density.

As an example, in the chemical formula 1, the divalent aromatic organic groups of Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ may be represented by the following chemical formula 2 or chemical formula 6.

[Chemical formula 2]

(In the above chemical formula 2, R ₄ is independently C ₁ -C ₆ alkyl or C ₁ -C ₆ alkoxy, and p is an integer from 0 to 4.)

[Chemical Formula 3]

(In the above chemical formula 3, L is a C ₁ -C ₆ alkylene group, *-C(=O)-*, *-O-*, *-S-* or *-S(=O) ₂ -*, R ₅ and R ₆ are each independently a C ₁ -C ₆ alkyl or a C ₁ -C ₆ alkoxy, and q and r are each independently an integer from 0 to 4.)

The above multifunctional amine curing agent can control the properties of a one-component epoxy adhesive composition containing the same by controlling the structures of Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ in the above chemical formula 1.

In the chemical formula 1 above, a multifunctional amine curing agent in which Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ have a structure of the chemical formula 2 or 3 may be preferred because it may have excellent heat resistance and excellent mechanical strength, but is not limited thereto as long as it does not impair the properties of the one-component epoxy adhesive composition.

As another embodiment, in the chemical formula 1, R ₁ , R ₂ and R ₃ are each independently hydrogen, methyl or ethyl, j, k, l, m, n and o are each independently an integer from 1 to 3, and Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ may each be a straight-chain C ₁ -C ₃ alkylene group or a group represented by the chemical formula 3.

The multifunctional amine curing agent having the structure described above is not particularly limited as long as it has properties at a commercially available level, but as an example, it can be mixed with an epoxy resin with excellent dispersibility, and an epoxy adhesive composition containing it can maintain excellent tensile strength and excellent heat resistance and can have excellent flexural strength and excellent impact strength, and thus can be preferred because it can have excellent static strength and excellent dynamic strength at the same time.

As an embodiment, in the chemical formula 3, L is *-C(=O)-* or *-S(=O) ₂ -*, R ₅ and R ₆ are each independently methyl or ethyl, and q and r can each independently be an integer from 0 to 1.

Specifically, in the chemical formula 3, L is *-S(=O) ₂ -*, and q and r satisfy 0, so that Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ in the chemical formula 1 can be unsubstituted divalent aromatic organic groups.

The polyfunctional amine curing agent containing the above chemical formula 3 has an unsubstituted structure and thus can have excellent compatibility with an epoxy resin, and an epoxy adhesive composition containing the same can have excellent heat resistance and excellent mechanical strength, and thus may be preferred; however, this is not limited as long as it does not impair the physical properties of the one-component epoxy adhesive composition.

As an embodiment, the multifunctional amine curing agent may be represented by the following chemical formula 4 or chemical formula 5.

[Chemical Formula 4]

[Chemical Formula 5]

The multifunctional amine curing agent represented by the above chemical formula 4 contains an aromatic divalent organic group, so that a one-component epoxy adhesive composition containing the same can simultaneously have excellent static strength, excellent dynamic strength, and heat resistance, and can also have excellent adhesive strength to different materials.

In addition, the polyfunctional amine curing agent represented by the chemical formula 5 contains an aliphatic amine group, and thus can have better flexural strength and impact strength than the polyfunctional amine curing agent represented by the chemical formula 4, and can have better adhesion to different materials.

That is, the multifunctional amine curing agent represented by the chemical formula 4 or 5 can control the static strength and dynamic strength of a one-component epoxy adhesive composition containing it by controlling the structure of six amine groups, and since all of them have excellent tensile strength, flexural strength, impact strength, and shear strength for different materials, those skilled in the art can control and use them by considering each property.

As an example, the polyfunctional amine curing agent represented by the chemical formula 4 may be in a solid state at room temperature since it has a high crystallinity, and the amine curing agent represented by the chemical formula 5 may be in a liquid state at room temperature.

That is, the multifunctional amine curing agent represented by the chemical formula 5 can have a one-component epoxy adhesive composition having better dispersibility than the multifunctional amine curing agent represented by the chemical formula 4.

As an embodiment, the one-component epoxy adhesive composition may contain 1 to 10 parts by weight of a multifunctional amine curing agent per 100 parts by weight of the epoxy resin.

The above-mentioned one-component epoxy adhesive composition is not necessarily limited to the content of the multifunctional amine hardener within the above range as long as it has mechanical properties at a commercially acceptable level. However, it may be preferred to include the multifunctional amine hardener in the content within the above range because it can have excellent curing behavior and excellent curing density, and can simultaneously have excellent tensile strength, excellent flexural strength, and excellent impact strength.

Specifically, the one-component epoxy adhesive composition may contain 1 to 5 parts by weight, more specifically 1 to 3.5 parts by weight, of a multifunctional amine curing agent represented by the chemical formula 4, per 100 parts by weight of the epoxy resin.

In addition, specifically, the one-component epoxy adhesive composition may contain 3 to 10 parts by weight, more specifically 3 to 7 parts by weight, of a multifunctional amine curing agent represented by the chemical formula 5, per 100 parts by weight of the epoxy resin.

The above-mentioned one-component epoxy adhesive composition has low impact strength and flexural strength when included in amounts below the above range, and has low tensile strength for heterogeneous materials when included in amounts exceeding the above range. Therefore, it may be preferred to include a multifunctional amine hardener in an amount within the above range, but this is not necessarily limited unless it impairs the physical properties to an uncommercially unavailable level.

Below, the epoxy resin in the one-component epoxy adhesive composition is described.

The above epoxy resin may be used without limitation as long as it has two or more epoxy groups in the molecule. As an example, the base epoxy resin may have two or more epoxy groups in the molecule, and may be selected from saturated, unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic and heterocyclic polyepoxy compounds, and more specifically, may be one or two or more selected from bisphenol-type epoxy resins, glycidyl ether-type epoxy resins, glycidyl amine-type epoxy resins, phenol novolac-type epoxy resins and cresol novolac-type epoxy resins.

As an embodiment, the epoxy resin may be a bisphenol-based epoxy resin.

As described above, any epoxy resin can be used without limitation. However, in the present invention, it may be a preferred embodiment to use a bisphenol-based epoxy resin having excellent heat resistance and excellent tensile strength, and having an amine curing agent and a multifunctional amine curing agent included as curing agent components and excellent curing behavior.

Specifically, the bisphenol-based epoxy resin may be one or more selected from, for example, bisphenol A, bisphenol E, bisphenol F, bisphenol M, bisphenol S, and bisphenol H, and more specifically, may be bisphenol A-based epoxy resin, bisphenol F-based epoxy resin, and mixtures thereof, but is not limited thereto as long as it does not impair the properties of a one-component epoxy adhesive composition containing the same.

The above bisphenol-based epoxy resin may be liquid at room temperature and may have an epoxy equivalent weight of 100 to 600 g/eq, or 150 to 550 g/eq.

A two-component adhesive composition including a bisphenol-based epoxy resin satisfying the above range can provide a viscosity with good workability, and can have more advantageous characteristics in terms of improving mechanical properties such as impact strength for the bonded portion, including the above-described effects, but is not limited thereto.

Below, the amine curing agent of the one-component epoxy adhesive composition is described.

The above-mentioned one-component epoxy resin composition is not limited to an amine hardener as long as it is capable of curing, but it may be preferred to include an amine hardener in terms of having excellent mechanical strength.

As an embodiment, the amine curing agent may be an aliphatic amine curing agent, an alicyclic amine curing agent, an aryl amine curing agent, and an acid anhydride amine curing agent.

The above amine curing agent may be used without limitation as long as it has *-NH ₂ , but a one-component epoxy adhesive composition containing the above amine curing agent may have excellent tensile strength and may be preferred, and may have a usable level of flexural strength, but a one-component epoxy adhesive composition containing only an amine curing agent as a curing agent component may have low impact strength and flexural strength.

The above aliphatic amine curing agent may be, for example, one or more selected from diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, and isophoronediamine.

The above-mentioned alicyclic amine curing agent may be, for example, one or more selected from 1,3-bisaminomethylcyclohexane, bis(p-aminocyclohexyl)methane (PACM), norbornene diamine, 2,4-diamino-1-methylcyclohexane, 2,6-diamino-1-methylcyclohexane, and 1,2-diaminocyclohexane, and may be one or more selected from dicyandiamide, guanidine compounds, and acid anhydride-added amine curing agents additionally containing a basic functional group such as a cyano group.

The above aromatic amine curing agent may be one or more selected from, for example, diaminodiphenylmethane (DDM), m-phenylenediamine, diaminodiphenylsulfone (DDS), 2,4-toluenediamine, 2,6-toluenediamine, diethyltoluenediamine, trimethylenebis(4-aminobenzoate), polytetramethyleneoxide-di-p-aminobenzoate, 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene, 1,2-diaminobenzene, 1,3-diaminobenzene, 1,4-diaminobenzene, diaminodiphenyl oxide, 3,3',5,5'-tetramethyl-4,4'-diaminobiphenyl, and 3,3'-dimethyl-4,4'-diaminodiphenyl.

Examples of the above acid anhydride-based amine curing agent include, but are not limited to, one or more selected from phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, glutaric anhydride, methylhexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride.

Specifically, the amine curing agent may be an aliphatic amine curing agent that has excellent reactivity with excellent curing behavior and can produce a cured product having excellent mechanical properties, and more specifically, may be a dicyandiamide curing agent with excellent curing properties, but this is not limited as long as it does not impair the properties of the one-component epoxy adhesive composition containing the same.

As an embodiment, the one-component epoxy adhesive composition may contain 5 to 15 parts by weight of the amine curing agent, specifically 6 to 15 parts by weight, and more specifically 8 to 11 parts by weight, per 100 parts by weight of the epoxy resin.

A one-component epoxy adhesive composition containing an amine curing agent in the above range of contents may be preferred because it can maintain excellent tensile strength.

As another embodiment, the one-component epoxy adhesive composition may contain an amine curing agent and a polyfunctional amine curing agent in an equivalent amount equal to that of the epoxy resin.

Regarding the equivalents of the epoxy resin including the amine hardener and the polyfunctional amine hardener included in the above-mentioned one-component epoxy adhesive composition, it may be preferable to include the epoxy/amine in an equivalent ratio of 1:1, as this can have excellent curing behavior and can have excellent mechanical properties of the cured product.

In addition, as an embodiment, the one-component epoxy adhesive composition may contain the amine curing agent and the polyfunctional amine curing agent in a molar ratio of 80:20 to 99:1 when the amine curing agent and the polyfunctional amine curing agent are included in an equivalent ratio of 1:1 with the epoxy resin, specifically, 85:15 to 95:5, and more specifically, 90:10 to 95:5.

A one-component epoxy adhesive composition containing an amine curing agent and a multifunctional amine curing agent in the above molar ratio may be preferred because it maintains excellent heat resistance and excellent tensile strength, and may have excellent impact strength, excellent flexural strength, excellent curing density, and excellent shear strength for different materials.

Below, the toughening agent of the one-component epoxy adhesive composition is described.

A one-component epoxy adhesive composition including the above-mentioned toughening agent may have excellent toughness, and thus may be preferred because it has excellent tensile strength and excellent 100% modulus, and thus may not cause cracking when subjected to external impact.

As an embodiment, the toughening agent may be a mixture of a urethane-based toughening agent and a core-shell type toughening agent.

The above toughening agent can be used without limitation as long as it provides excellent toughness to the one-component epoxy adhesive composition, and as an example, it may include one or two or more selected from polypropylene oxide, polyethylene oxide, a urethane-based toughening agent, and a core-shell type toughening agent.

The above toughening agent can be used without limitation as long as it provides excellent toughness to the one-component epoxy adhesive composition, and as an example, it may include one or two or more selected from polypropylene oxide, polyethylene oxide, a urethane-based toughening agent, and a core-shell type toughening agent.

However, since the above-mentioned urethane-based toughening agent and core-shell-type toughening agent have excellent compatibility with bisphenol-based epoxy resin, they can maintain a viscosity with good workability, and the cured product cured with them can significantly reduce the breakage rate due to external impact, so it can be a desirable embodiment.

As an embodiment, the urethane-based toughening agent may be manufactured by including a polyol and a diisocyanate-based compound.

The above urethane-based toughening agent can be used without limitation as long as it contains a urethane bond, and may be manufactured by urethane polymerization including a polyol and a diisocyanate-based compound.

Specifically, the urethane-based toughening agent may be preferred for being capped at the terminal, as this makes it more non-reactive, and depending on the structure of the polyol and diisocyanate-based compound, a toughening agent with different physical properties can be prepared.

The above polyol may be, for example, one or more selected from polyethylene oxide, polypropylene oxide, ε-caprolactone, and polytetrahydrofuran, but is not intended to be limited thereto.

The above diisocyanate compound can be used without limitation as long as it reacts with the polyol and contains a urethane-based toughening agent, but as examples, tetra-methylene diisocyanate, penta-methylene diisocyanate, hexa-methylene diisocyanate, hepta-methylene diisocyanate or octa-methylene diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate (HDI), pentamethylene 1,5-diisocyanate, butylene 1,4-diisocyanate, trimethylhexamethylene 1,6-diisocyanate, 1-isocyanate-3,3,5-trimethyl-5-isocyanate methylcyclohexane (isophorone diisocyanate, IPDI), 1,4- or It may be one or more selected from 1,3-bis(methylisocyanate)cyclohexane (HXDI), cyclohexane 1,4-diisocyanate, 1-methylcyclohexane 2,4- or 2,6-diisocyanate, and methylene dicyclohexyl (4,4'-, 2,4'- or 2,2'-)diisocyanate (H12MDI).

The above core-shell type toughening agent may be a particle including a core manufactured with a monomer having two or more double bonds, and a shell partially or completely covering the surface of the core. More specifically, the core may be a rubber particle including an elastomer or a rubber polymer as a main component, and the shell may be a graft polymerized polymer, but is not limited thereto. In addition, the rubber included in the core-shell type toughening agent may be acrylic rubber, silicone rubber, urethane rubber, styrene-butadiene rubber, butadiene rubber, etc. independently selected from the core and the shell, but is not limited thereto if it is commonly used in the relevant field.

The core-shell type toughening agent may have an average particle size of 0.01 to 20 ㎛, more preferably 0.1 to 5 ㎛, but may be used without limitation as long as it does not impair the properties of the one-component epoxy adhesive composition.

As an embodiment, the toughening agent may be a mixture of a urethane-based toughening agent and a core-shell type toughening agent in a mass ratio of 3:1 to 1:1, specifically, a mixture of 3:1 to 3:2.

The toughening agent mixed in the above mass ratio is not particularly limited as long as it does not impair physical properties, but since it simultaneously has the excellent flexibility of the urethane-type toughening agent and the excellent impact resistance of the core-shell type toughening agent, a one-component epoxy adhesive composition containing it has excellent 100% modulus and impact resistance, and thus may not be peeled or damaged by external impact.

As an embodiment, the one-component epoxy adhesive composition may contain 50 to 150 parts by weight of the toughening agent, specifically 70 to 120 parts by weight, and more specifically 90 to 120 parts by weight, per 100 parts by weight of the epoxy resin.

The above-mentioned one-component epoxy adhesive composition can use the content of the included toughening agent without limitation as long as it does not impair the physical properties; however, it may be preferred to include the toughening agent in the content within the above range in terms of having a viscosity with good workability and excellent dispersibility of the toughening agent.

Below, the curing accelerator of the one-component epoxy adhesive composition is described.

A one-component epoxy adhesive composition containing the above-mentioned curing accelerator can shorten the curing time, thereby providing excellent workability and excellent mechanical strength of a cured product.

As an embodiment, the curing accelerator may be 3-phenyl-1,1-dimethylurea.

The above curing accelerator can be used without limitation as long as it can increase the curing behavior of the one-component epoxy adhesive, and as an example, it can be one or more selected from an imidazole-based accelerator, a urea-based accelerator, and a tertiary amine-based accelerator, but as long as it is recognizable by a person skilled in the art, it can be used without limitation. However, the one-component epoxy adhesive composition containing the 3-phenyl-1,1-dimethylurea can have a superior curing behavior and superior heat resistance than those containing other curing accelerators, and thus can be more preferred.

Among the curing accelerators that may be included in the above-mentioned one-component epoxy adhesive composition, the imidazole-based curing accelerators include, for example, 2-methyl imidazole, 2-heptadecyl imidazole, 2-phenyl imidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, 2,4-diamino-6-[2'-methylimidazoleyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2-undecylimidazole, 3-heptadecylimidazole, 2-phenylimidazole, 2-phenylimidazoline, 1,2-dimethylimidazole, It may be one or more selected from 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, etc.

The above urea-based curing accelerator may be, for example, one or more selected from p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, 3,4-dichlorophenyl-N,N-dimethylurea, etc.

Examples of the above tertiary amine curing accelerator include one or more selected from benzyldimethylamine, triethanolamine, triethylenediamine, dimethylaminoethanol, 2-(dimethylaminomethyl)phenol, tri(dimethylaminomethyl)phenol, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undeca-7-ene, and the like.

As an embodiment, the one-component epoxy adhesive composition may contain 1 to 5 parts by weight of the curing accelerator per 100 parts by weight of the epoxy resin, specifically 1 to 3 parts by weight, and more specifically 1 to 1.5 parts by weight.

If the above-mentioned one-component epoxy adhesive composition contains a large amount of a curing accelerator, the brittleness of the cured product increases and may be damaged by external impact. Therefore, it may be preferred to contain the curing accelerator in the above-mentioned range of contents. However, as long as it does not impair the physical properties of the one-component epoxy adhesive, the amount of the curing accelerator is not necessarily limited to the above-mentioned range.

As an embodiment, the one-part epoxy adhesive composition may further include a filler.

Since the above filler is included in a one-component epoxy adhesive composition and occupies a large volume, not only can the content of the one-component epoxy adhesive composition used be reduced, but a one-component epoxy adhesive composition including the filler can have better thermal conductivity, chemical resistance, mechanical strength, and wear resistance, and thus may be preferred.

The above filler may be used without limitation as long as it is a filler recognizable by a person skilled in the art, but as an example, any one or two or more selected from the group consisting of quartz, limestone, mica, fumed silica, calcium carbonate, magnesium carbonate, aluminum nitride, boron nitride, silicon nitride, aluminum hydroxide, hydrotalcite, magnesium hydroxide, calcium hydroxide, wollastonite, bentonite, silica, alumina, titanium oxide, barium sulfate, calcium sulfate, talc, and glass fiber may be used.

As an embodiment, the filler may be a mixture of calcium carbonate, aluminum hydroxide and fumed silica.

A one-component epoxy adhesive composition containing a filler mixed in the above combination may be preferred in terms of excellent outstanding wear resistance, excellent chemical resistance, excellent thermal conductivity and mechanical strength, but is not necessarily limited thereto.

Specifically, the above filler, which is a mixture of calcium carbonate, aluminum hydroxide and fumed silica in a mass ratio of 1:1:1, can be distributed with excellent dispersion in a one-component epoxy adhesive composition, and a one-component epoxy adhesive composition containing the same may have better physical properties than the above and may be preferred; however, as long as it has physical properties at a commercially available level, this is not limited.

As an embodiment, the one-component epoxy adhesive composition may contain 1 to 10 parts by weight of the filler, specifically 3 to 10 parts by weight, and more specifically 5 to 10 parts by weight, per 100 parts by weight of the epoxy resin.

A one-component epoxy adhesive composition containing a filler in the above range may be preferred in terms of containing the filler with excellent dispersion and having excellent tensile strength and flexural strength of the cured product; however, it is not necessarily limited to the above content unless the physical properties are impaired.

The present invention provides a cured product obtained by curing the one-component adhesive composition.

The above-mentioned one-component epoxy adhesive composition may be cured by heat curing, and contains a multifunctional amine curing agent, so as to have a better curing density than conventional one-component epoxy adhesive compositions and to shorten the curing time.

As an embodiment, the cured product is a one-component epoxy adhesive composition that is heat-cured at 150 to 200° C., specifically, at 180 to 200° C. for 20 to 40 minutes.

In one embodiment, the cured product may have a storage modulus of 5 to 20 MPa as measured by ASTM D1238, a flexural strength of 120 to 200 MPa, and an impact strength of 45 to 70 J/m.

The above-mentioned cured product is cured by including a one-component epoxy adhesive composition containing a multifunctional amine curing agent, and thus has excellent curing density and can have excellent mechanical strength, particularly dynamic strength.

The above-mentioned cured product maintains excellent heat resistance and excellent tensile strength, and can have excellent impact strength and flexural strength, so that it can be usefully used as a molding rather than an adhesive.

The adhesive article of the present invention comprises a first substrate layer, a second substrate layer bonded to the first substrate layer, and an adhesive layer formed by curing the one-component epoxy adhesive composition between the first substrate layer and the second substrate layer.

As an embodiment, the first substrate layer and the second substrate layer may be a composite material including one or more independently selected from metal, steel plate, wood, film, tile, plastic, glass, resin, ceramic, concrete, carbon material, and fiber.

Since the above-mentioned one-component epoxy adhesive composition has excellent adhesive strength between different materials, the first substrate layer and the second substrate layer can be bonded without limitation.

In one embodiment, the adhesive article may have a shear strength as measured by ASTM D1002 of 5 to 40 MPa, specifically 10 to 40 MPa, and more specifically 15 to 40 MPa.

An adhesive having a shear strength in the above range may not be peeled off even when bonded to a dissimilar material using the one-component epoxy adhesive composition, as it has a shear strength that is commercially acceptable or excellent.

Hereinafter, the single-component epoxy adhesive composition according to the present invention will be described in more detail through examples. However, the following examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms. In addition, unless otherwise defined, all technical terms and scientific terms have the same meaning as generally understood by one of ordinary skill in the art to which the present invention belongs. In addition, the terminology used in the description of the present invention is only for the purpose of effectively describing specific examples, and is not intended to limit the present invention.

[measurement method]

1. Shear strength measurement

Two materials were used among steel (SPRC440, 25×100×1.6 mm), aluminum (AL6061, 25×100×2.0 mm), and composite material (CFRP, 25×100×2.8 mm), and each of the two materials used was steel-steel, steel-composite, aluminum-composite, or steel-aluminum, and the adhesive composition was overlapped to form an adhesive layer of 25×12.7 mm on the two materials, and then cured at 180°C for 20 minutes.

After curing, the test was performed using a universal testing machine (UTM 5982, INSTRON) according to ASTM D1002, at a spin head speed of 1.3 mm/min.

[Manufacturing Example 1]

In a round-bottom flask containing 30 mL of hexane, 20 g of isophorone diisocyanate (PDI), 0.9 g of 4-methoxyphenol, and 0.25 g of dibutyltin dilaurate (DBTDL) were added, stirred at 45 °C under a nitrogen atmosphere until dissolved, and 59.59 g of pentaerythritol triacrylate (PETA) was added dropwise using a dropping funnel. The reaction was then carried out by stirring at 60 °C for 6 hours, and when the reaction was completed, hexane was removed using a rotary evaporator to obtain reactant A.

Afterwards, 3 g of the above A and 6.36 diaminophenol sulfone (DDS) were added to a round-bottom flask containing 20 ml of methanol, and the mixture was stirred at 80° C. for 24 hours to react. After the reaction was completed, methanol was removed using a rotary evaporator to prepare a multifunctional amine curing agent B.

The result of elemental analysis of the manufactured multifunctional amine curing agent B was C: 58.09%, H: 5.55%, N: 8.55%, S: 7.78%, and the result of NMR measurement (300 MHz, DMSO-d ₆ ) was δ (ppm) = 7.46 (m, 24H), 6.59 (m, 24H), 5.99 (m, 18H), 4.12-4.14 (m, 16H), 3.36 (m, 13H), 1.48 (m, 4H), 0.99 (m, 5H), 0.97 (m, 6H), thereby completing the synthesis.

[Manufacturing Example 2]

Reactant A was prepared in the same manner as in Manufacturing Example 1 above.

Thereafter, 3 g of the compound A prepared above and 9.9 g of ethylenediamine (ED) were added to a round-bottom flask containing 20 ml of methanol, and the mixture was stirred at 80° C. for 24 hours to react. After completion of the reaction, methane was removed using a rotary evaporator to prepare a multifunctional amine curing agent C.

Thereafter, the result of elemental analysis of the manufactured multifunctional amine curing agent C was confirmed as C: 52.52%, H: 10.87%, N: 16.69%, and the result of NMR measurement (300 MHz, CDCl ₃ ) was confirmed as δ (ppm) = 3.39 (s, 16H), 3.26 (m, 12H), 2.64-3.39 (m, 24H), 2.36 (m, 12H), 1.49 (s, 22H), 1.03 (m, 5H), 0.81 (m, 6H), and the synthesis was completed.

[Examples 1 to 4]

22.5 g of bisphenol A diglycidyl (MOMENTIVE, EPIKOTE 828) as an epoxy resin was added to a paste mixer, 22.75 g of a toughening agent, 2.0 g of a filler, and 0.3 g of 3-phenyl-1,1-dimethylurea as a curing accelerator component were added, and dicyandiamide (DICY, AIR PRODUCTS, active hydrogen equivalent weight: 21 g/eq) and Manufacturing Example 1 or Manufacturing Example 2 as a polyfunctional amine curing agent were added in the contents shown in Table 1 below, and stirred for 5 minutes under vacuum conditions to prepare a one-component epoxy adhesive composition.

At this time, the toughening agent was used by mixing a urethane-based toughening agent (Huntsman, DY965) and a core-shell type toughening agent (KANEKA, MX 267) at a mass ratio of 3:2, and the filler was used by mixing calcium carbonate, aluminum hydroxide, and fumed silica at a weight ratio of 1:1:1.

The single-component epoxy adhesive composition manufactured thereafter was measured using the above-mentioned measuring method and is shown in Table 2 below.

[Comparative Example 1]

A one-component epoxy adhesive composition was prepared in the same manner as in Example 1 except that the polyfunctional amine curing agent was not included and 2.4 g of dicyandiamide was included.

[Comparative Example 2]

In the above Example 1, a one-component epoxy adhesive composition was prepared in the same manner as above, except that the toughening agent was not included.

The single-component epoxy adhesive composition manufactured thereafter was measured using the above-mentioned measuring method and is shown in Table 2 below.

[Comparative Example 3]

In the above Example 1, a one-component epoxy adhesive composition was prepared in the same manner as above, except that the curing accelerator was not included.

The single-component epoxy adhesive composition manufactured thereafter was measured using the above-mentioned measuring method and is shown in Table 2 below.

(g) Epoxy resin DICY Manufacturing example 1 Manufacturing example 2 Strengthener Filler Curing accelerator Example 1 22.5 2.27 0.37 - 22.75 2 0.3 Example 2 22.5 1.82 0.74 - 22.75 2 0.3 Example 3 22.5 2.27 - 0.73 22.75 2 0.3 Example 4 22.5 1.82 - 1.45 22.75 2 0.3 Comparative Example 1 22.5 2.40 - - 22.75 2 0.3 Comparative Example 2 22.5 2.27 0.37 - - 2 0.3 Comparative Example 3 22.5 2.27 0.37 - 22.75 2 -

㎫ Steel-steel steel-composite Steel-Aluminum Aluminum-composite Example 1 29.56 10.88 21.74 9.84 Example 2 26.46 9.32 20.80 6.24 Example 3 25.92 13.87 17.57 10.83 Example 4 26.78 14.06 20.19 7.51 Comparative Example 1 24.05 9.90 12.10 7.95 Comparative Example 2 20.11 5.12 10.57 3.84 Comparative Example 3 20.35 6.18 12.57 5.48

In the above Table 2, Examples 1 to 4 had a shear strength of 25 MPa or more for steel-steel, and Comparative Example 1 had a shear strength of 24.05 MPa, confirming that Examples 1 to 4 had superior shear strength for similar materials.

In the above Table 3, it was confirmed that Examples 1 to 4 had particularly outstanding shear strengths for steel-aluminum, and similar or superior shear strengths for other dissimilar materials.

In the above Table 3, Comparative Example 2 did not include a toughening agent and therefore had lower shear strength than Examples 1 to 4, and Comparative Example 3 did not include a hardening accelerator and therefore had low hardening behavior, so when hardened for the same amount of time, it had low shear strength.

Therefore, the one-component epoxy adhesive composition of the present invention has superior shear strength for the same material than the conventional one-component epoxy composition, and has remarkable shear strength for different materials, so that it can be usefully used as an adhesive for different materials for recent lightweighting. In addition, although it was not measured in the present invention, it includes a multifunctional amine curing agent containing six amine groups, so that it has excellent tensile strength, excellent impact strength, and excellent flexural strength, and also has excellent heat resistance, so that it can be applied to a wider range of industrial fields.

Although the present invention has been described through specific matters and limited examples and comparative examples, these have been provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations from this description.

Therefore, the idea of the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the claims are considered to belong to the scope of the idea of the present invention.

Claims (18)

A one-component epoxy adhesive composition comprising an epoxy resin, an amine curing agent, a curing accelerator, a toughening agent, and a multifunctional amine curing agent represented by the following chemical formula 1:
[Chemical Formula 1]

In the above chemical formula 1,
R ₁ , R ₂ and R ₃ are independently hydrogen or C ₁ -C ₆ alkyl,
j, k, l, m, n and o are independently integers from 1 to 6,
Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ are each independently a straight-chain or branched C ₁ -C ₁₂ alkylene group or a divalent aromatic organic group. In paragraph 1,
A one-component epoxy adhesive composition wherein in the chemical formula 1, the divalent aromatic organic groups of Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ are represented by the following chemical formula 2 or chemical formula 3:
[Chemical formula 2]

In the above chemical formula 2,
R ₄ is independently C ₁ -C ₆ alkyl or C ₁ -C ₆ alkoxy,
p is an integer from 0 to 4.
[Chemical Formula 3]

In the above chemical formula 3,
L is a C ₁ -C ₆ alkylene group, *-C(=O)-*, *-O-*, *-S-* or *-S(=O) ₂ -*,
R ₅ and R ₆ are independently C ₁ -C ₆ alkyl or C ₁ -C ₆ alkoxy,
q and r are integers from 0 to 4, independent of each other. In paragraph 1,
In the above chemical formula 1,
R ₁ , R ₂ and R ₃ are independently hydrogen, methyl or ethyl,
j, k, l, m, n and o are independently integers from 1 to 3,
A one-component epoxy adhesive composition wherein Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ and Y ₆ are each independently a straight-chain C ₁ -C ₃ alkylene group or are represented by the following chemical formula 3:
[Chemical Formula 3]

In the above chemical formula 3,
L is a C ₁ -C ₆ alkylene group, *-C(=O)-*, *-O-*, *-S-* or *-S(=O) ₂ -*,
R ₅ and R ₆ are independently C ₁ -C ₆ alkyl or C ₁ -C ₆ alkoxy,
q and r are integers from 0 to 4, independent of each other. In the third paragraph,
A one-component epoxy adhesive composition wherein in the chemical formula 3 above, L is *-C(=O)-* or *-S(=O) ₂ -*, R ₅ and R ₆ are each independently methyl or ethyl, and q and r are each independently an integer from 0 to 1. In paragraph 1,
The above multifunctional amine curing agent is a one-component epoxy adhesive composition represented by the following chemical formula 4 or chemical formula 5:
[Chemical Formula 4]

[Chemical Formula 5]
In paragraph 1,
The above epoxy resin is a one-component epoxy adhesive composition which is a bisphenol-based epoxy resin. In paragraph 1,
The above one-component epoxy adhesive composition is a one-component epoxy adhesive composition containing 1 to 10 parts by weight of a multifunctional amine curing agent per 100 parts by weight of an epoxy resin. In paragraph 1,
The above one-component epoxy adhesive composition is a one-component epoxy adhesive composition containing 5 to 15 parts by weight of an amine hardener per 100 parts by weight of an epoxy resin. In paragraph 1,
A one-component epoxy adhesive composition wherein the above amine curing agent is one or more selected from an aliphatic amine curing agent, an alicyclic amine curing agent, an aromatic amine curing agent, and an acid anhydride amine curing agent. In paragraph 1,
A one-component epoxy adhesive composition wherein the above toughening agent is a mixture of a urethane-based toughening agent and a core-shell type toughening agent. In paragraph 1,
The above one-component epoxy adhesive composition is a one-component epoxy adhesive composition containing 50 to 150 parts by weight of a toughening agent per 100 parts by weight of epoxy resin. In paragraph 1,
A one-component epoxy adhesive composition wherein the above curing accelerator is 3-phenyl-1,1-dimethylurea. In paragraph 1,
The above one-component epoxy adhesive composition is a one-component epoxy adhesive composition containing 1 to 5 parts by weight of a curing accelerator per 100 parts by weight of epoxy resin. In paragraph 1,
The above one-component epoxy adhesive composition further comprises 1 to 10 parts by weight of a filler per 100 parts by weight of the epoxy resin. A cured product obtained by curing a one-component epoxy adhesive composition selected from any one of claims 1 to 14. First layer of substrate;
A second substrate layer bonded to the first substrate layer; and
An adhesive article comprising an adhesive layer cured with a one-component epoxy adhesive composition selected from any one of claims 1 to 14 between the first substrate layer and the second substrate layer. In Article 16,
An adhesive product wherein the first substrate layer and the second substrate layer are independently one or more composite materials selected from metal, steel plate, wood, film, tile, plastic, glass, resin, ceramic, concrete, carbon material, and fiber. In Article 16,
The above adhesive product is an adhesive product having a shear strength of 5 to 20 MPa as measured by ASTM D1002.