A (meth)acrylate-based adhesive composition for a two-step adhesive system

Abstract

This invention relates to a (meth)acrylate-based adhesive composition for a two-step adhesive system, the composition comprising: (a) a (meth)acrylate component comprising: (a-1) a high-Tg (meth)acrylate monomer having a glass transition temperature (Tg) of not less than 80°C, preferably not less than 95°C, more preferably not less than 100°C; (b) a bismaleimide compound of formula (I): wherein R is a substituted or unsubstituted arylene; a substituted or unsubstituted alkylene; or a combination of a substituted or unsubstituted arylene and a substituted or unsubstituted alkylene, optionally interrupted by O or S; (c) a thermoplastic elastomer selected from SBS, SIS, SIBS, SEBS, and SEPS block copolymers; (d) a curing initiator selected from peroxides; and (e) a curing accelerator; and (f) optionally, an additive. The invention also relates to cured products obtained from the composition, and articles comprising the activated product or assembled using the composition.

Description

Technical Field

[0001] This invention relates to an (meth)acrylate-based adhesive composition for a two-step adhesive system, a cured product obtained from the composition, and articles comprising the cured product or assembled using the composition. The adhesive achieved using this composition exhibits improved high-temperature resistance, rapid curing time, and good impact resistance. Technical Background Liquid adhesive compositions have long been used for sealing, retaining, bonding, and threadlocking applications, and have become a standard component of assembly production and the maintenance of machinery, tools, etc. Among the liquid adhesive compositions commonly used in these applications, single-component, two-component, and two-step formulations are employed, depending on the performance requirements they are designed to meet and the ingredients used to prepare the composition.

[0003] In high-temperature applications, epoxy adhesives are the mainstream adhesives. However, epoxy adhesives require heat curing and have a long curing time.

[0004] Acrylic adhesives have poor thermal properties at high temperatures, such as above 100°C, but they can meet the market demand for rapid curing.

[0005] In practice, it is necessary to improve the thermal properties of acrylic adhesives while ensuring a short setting time. Summary of the Invention

[0006] Through in-depth research, the inventors of this invention have discovered that by specifically selecting the components of the (meth)acrylate-based adhesive composition for a two-step adhesive system, improved thermal properties, rapid setting time, and good impact resistance can be achieved while maintaining good room temperature adhesion.

[0007] In a first aspect, this application provides an (meth)acrylate-based adhesive composition for a two-step adhesive system, said composition comprising or consisting of the following: (a) A (meth)acrylate component, comprising: (a-1) A high Tg (meth)acrylate monomer with a glass transition temperature (Tg) of not less than 80°C, preferably not less than 95°C, and more preferably not less than 100°C; (b) Bismaleimide compounds of formula (I): Wherein R is a substituted or unsubstituted arylene; a substituted or unsubstituted alkylene; or a combination of a substituted or unsubstituted arylene and a substituted or unsubstituted alkylene, optionally interrupted by O or S; (c) Thermoplastic elastomers selected from SBS, SIS, SIBS, SEBS, and SEPS block copolymers; (d) Curing initiators selected from peroxides, and (e) Curing accelerators, and (f) Additives that are optional.

[0008] In another aspect, this application provides a cured product obtained from the composition of this application.

[0009] On the other hand, this application provides an article comprising a cured product of this application or assembled using a composition of this application. For example, the article may be an electric motor, and in particular, magnets may be bonded to the rotor or stator of the electric motor using the composition of this application.

[0010] In another aspect, this application provides a method for bonding a substrate using the composition of this application.

[0011] The advantages of this invention include at least the following: (1) By combining components (a) to (e) or components (a) to (f), the adhesive properties achieved by the composition of this application at high temperatures, such as above 100°C or even 180°C, can be improved, while the setting time of the composition is fast, such as within 5 minutes, or even within 2 minutes, or even no more than 1 minute, and the adhesive properties at room temperature are also very good. (2) Specifically, according to ISO 4587, the lap shear strength of the bonded at 180°C can be higher than 650 psi, even higher than 800 psi, even higher than 1000 psi, while according to ISO 4587, the lap shear strength of the bonded at room temperature can be higher than 1500 psi, even higher than 1900 psi, even higher than 2000 psi. (3) In addition, the cured product of the composition of this application can achieve good impact resistance. Attached Figure Description

[0012] Figures 1A to 2C The illustration schematically shows the bonding of a magnet to the rotor or stator of an electric motor using the composition of this application. Detailed Implementation

[0013] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the invention. Unless otherwise expressly stated, each aspect described may be combined with any other one or more aspects. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.

[0014] Unless otherwise stated, the terminology used in the context of this invention shall be interpreted according to the following definitions.

[0015] Unless otherwise stated, all wt% or weight % values ​​cited in this article are weight percentages.

[0016] Unless otherwise stated, the terms “a,” “an,” and “the” as used herein include both singular and plural references.

[0017] The term “comprising, comprises” as used herein is synonymous with “including, includes” or “containing, contains” and is inclusive or open-ended, and does not exclude additional, unlisted members, elements or process steps.

[0018] The term “composed of” as used in this document is closed and excludes any additional, undescribed, intentionally added members, elements, or process steps.

[0019] The terms “at least one” or “one or more” used in this article to define components refer to the type of component, not the absolute number of molecules.

[0020] In this document, the terms “about”, “approximately”, etc., which are related to numerical values, are all exponentially expressed as ±10%, preferably ±5%. All numerical values ​​in this document should be understood as being modified by the term “about”.

[0021] As used herein, the term "(meth)acrylate-based adhesive composition" means that the composition contains (meth)acrylate as the main curing component, and preferably contains less than 1% by weight, more preferably less than 0.5% by weight, more preferably less than 0.1% by weight, and most preferably 0% of an epoxy portion or a silicone-modified (meth)acrylate portion.

[0022] Unless otherwise stated, the representation of numerical endpoints includes all numbers and fractions contained in the corresponding range, as well as the endpoints represented.

[0023] Unless otherwise defined, all terms used in this invention, including technical and scientific terms, shall have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] The following describes in detail the (meth)acrylate-based adhesive compositions used in two-step adhesive systems.

[0025] Component (a): (meth)acrylate component The composition of this application comprises (a) a (meth)acrylate component as a first essential ingredient. The (meth)acrylate component (a) undergoes a curing reaction to form an adhesive for bonding and is the main reactive component of the composition.

[0026] Component (a) must contain a (meth)acrylate monomer with a high glass transition temperature (Tg) of not less than 80°C, preferably not less than 95°C, more preferably not less than 100°C, although any conventionally used (meth)acrylate monomer may be used herein.

[0027] In this application, (meth)acrylates with a glass transition temperature (Tg) of not less than 80°C are referred to as "high Tg (meth)acrylates" (hereinafter referred to as component a-1). Correspondingly, (meth)acrylates with a glass transition temperature (Tg) of less than 80°C are referred to as "low Tg (meth)acrylates" (hereinafter referred to as component a-0).

[0028] In this application, (meth)acrylates with a high glass transition temperature (Tg) greater than 95°C may be referred to as "ultra-high Tg (meth)acrylates" (hereinafter referred to as component a-1-1).

[0029] For example, the Tg of a high Tg (meth)acrylate monomer can be not lower than 82°C, not lower than 84°C, not lower than 86°C, not lower than 88°C, not lower than 90°C, not lower than 92°C, not lower than 94°C, not lower than 96°C, not lower than 98°C, not lower than 100°C, not lower than 105°C, not lower than 110°C, but preferably not higher than 250°C, for example not higher than 240°C, not higher than 230°C, not higher than 220°C, not higher than 210°C, not higher than 200°C.

[0030] The Tg value mentioned here was determined using the DSC (Differential Scanning Calorimetry) method.

[0031] The high Tg (meth)acrylate monomers useful in this application can be monofunctional or polyfunctional, such as bifunctional.

[0032] As used in this article, "monofunctional" means that a (meth)acrylate monomer has one (meth)acryloyl group. "Polyfunctional" means that a (meth)acrylate monomer has more than one (meth)acryloyl group. "Bifunctional" means that a (meth)acrylate monomer has two (meth)acryloyl groups.

[0033] Monofunctional and polyfunctional high-Tg (meth)acrylates and combinations thereof can be used in this application, provided that their Tg values ​​are higher than 80°C, preferably higher than 95°C, and more preferably higher than 100°C.

[0034] Preferably, the content of high Tg (meth)acrylate monomer (a-1) in the composition can reach a certain level, for example, not less than 30% by weight based on the total weight of the composition, to achieve better results. In particular, for better results, ultra-high Tg (meth)acrylate may be included.

[0035] Examples of high Tg (meth)acrylate monomers (a-1) include, but are not limited to, 3,3,5-trimethylcyclohexyl methacrylate (TMCHMA) (Tg=145℃), ethoxylated (2)bisphenol A dimethacrylate (Tg=115℃), isobornyl methacrylate (Tg=110℃), cyclohexyl methacrylate (Tg=92℃), tricyclodecanediethanol diacrylate (Tg=186℃), methyl 2-(allyloxymethyl)acrylate (Tg=84℃), isobornyl acrylate (Tg=96℃), 3,3,5-trimethylcyclohexyl acrylate (Tg=81℃), N-[3-(dimethylamino)propyl]methacrylamide (Tg=134℃), and dicyclopentyl methacrylate (Tg=175℃). (Tg=120℃), dicyclopentenyl methacrylate, dicyclopentenyl acrylate (Tg=120℃), dicyclopentyl acrylate (Tg=120℃), 4-tert-butylcyclohexyl methacrylate (Tg=117℃), 1,3-butanediol dimethacrylate (Tg=85℃), or combinations thereof.

[0036] In addition to high-Tg (meth)acrylate monomers, component (a) of this application may optionally contain low-Tg (meth)acrylate monomers (a-0), which provide a good balance between room-temperature and high-temperature adhesion. If low-Tg (meth)acrylate monomers are present, their amount can be low to avoid negatively impacting high-temperature resistance; for example, based on the total weight of the composition, the content of low-Tg (meth)acrylate monomers may be less than 15% by weight, less than 10% by weight, less than 8% by weight, less than 6% by weight, less than 5% by weight, or less than 4% by weight. If the content of low-Tg (meth)acrylate monomers is too high, the desired effect cannot be achieved.

[0037] Based on the total weight of the composition, the content of the (meth)acrylate component (a) in the composition can be 31 to 85 wt%, 31 to 70 wt%, preferably 40 to 60 wt%, for example 33 wt%, 35 wt%, 38 wt%, 41 wt%, 44 wt%, 45 wt%, 47 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 57 wt%, 60 wt%, 62 wt%, 65 wt%, 67 wt%, 68 wt%, or any range between the two values ​​mentioned above.

[0038] In component (a), the content of the high-Tg (meth)acrylate monomer (a-1) can be 90-100% by weight of component (a). For example, the content of the high-Tg (meth)acrylate monomer (a-1) in the composition can be 30-70% by weight, preferably 40-60% by weight, such as 33%, 35%, 38%, 41%, 44%, 45%, 47%, 48%, 50%, 52%, 55%, 57%, 60%, 62%, 65%, 67%, 68%, or any range between the above two values, based on the total weight of the composition. If the amount of the high-Tg (meth)acrylate monomer is below the specified lower limit, the desired high-temperature resistance cannot be achieved.

[0039] Preferably, the content of the ultra-high Tg (meth)acrylate monomer (a-1-1) in the composition can be 10 to 70% by weight, more preferably 15 to 60% by weight, for example 12% by weight, 15% by weight, 18% by weight, 20% by weight, 23% by weight, 25% by weight, 27% by weight, 30% by weight, 33% by weight, 35% by weight, 38% by weight, 41% by weight, 44% by weight, 45% by weight, 47% by weight, 48% by weight, 50% by weight, 52% by weight, 55% by weight, 57% by weight, 60% by weight, 62% by weight, 65% by weight, 67% by weight, 68% by weight, or any range between the above two values, based on the total weight of the composition.

[0040] Component (b): Bismaleimide compound As a second essential component, the composition of this application comprises a bismaleimide (BMI) compound having the following formula (I): Wherein R is a substituted or unsubstituted arylene; a substituted or unsubstituted alkylene; or a combination of a substituted or unsubstituted arylene and a substituted or unsubstituted alkylene, optionally interrupted by O or S.

[0041] Preferably, R represents: -substituted or unsubstituted phenylene, -Substituted or unsubstituted phenylene-alkylene-phenylene, -substituted or unsubstituted biphenylene-alkylene-biphenylene, or -Substituted or unsubstituted phenylene-O-phenylene-alkylene-phenylene-O-phenylene.

[0042] More preferably, the bismaleimide compound (b) is selected from: Wherein R' is a straight-chain or branched C1-C5 alkylene group, preferably methylene, ethylene, propylene and its isomers, butylene and its isomers, and more preferably methylene. R1 and R2 each independently represent hydrogen, straight-chain or branched C1-C5 alkyl groups, preferably hydrogen, alkyl, ethyl, propyl and their isomers, butyl and their isomers, and more preferably hydrogen.

[0043] Most preferably, the bismaleimide compound (b) is selected from: .

[0044] Based on the total weight of the composition, the content of bismaleimide compound (b) in the composition can be 3-30% by weight, preferably 6-20% by weight, for example 4.0% by weight, 5.5% by weight, 6.0% by weight, 6.5% by weight, 7.0% by weight, 7.5% by weight, 8.0% by weight, 8.5% by weight, 9.0% by weight, 9.5% by weight, 10.0% by weight, 10.5% by weight, 11.0% by weight, 11.5% by weight, 12.0% by weight, 12.5% ​​by weight, 15.0% by weight, 17.0% by weight, 19.0% by weight, 23.0% by weight, 25.0% by weight, 28.0% by weight, or any range between the two values ​​mentioned above.

[0045] Component (c): Thermoplastic elastomer As a third essential component, the compositions of this application include thermoplastic elastomers derived from SBS, SIS, SIBS, SEBS, and SEPS block copolymers.

[0046] As used herein, the term "SBS block copolymer" has its conventional meaning in the art, referring to a triblock copolymer derived from styrene and butadiene monomers and being a thermoplastic elastomer.

[0047] As used herein, the term "SIS block copolymer" has its conventional meaning in the art, referring to a triblock copolymer derived from styrene and isoprene monomers and being a thermoplastic elastomer.

[0048] As used herein, the term "SIBS block copolymer" has its conventional meaning in the art, referring to a block copolymer derived from styrene, butadiene, and isoprene monomers and being a thermoplastic elastomer.

[0049] As used herein, the term "SEBS block copolymer" has its conventional meaning in the art, namely hydrogenated SBS and a thermoplastic elastomer.

[0050] As used herein, the term "SEPS block copolymer" has its conventional meaning in the art, namely hydrogenated SIS and a thermoplastic elastomer.

[0051] Any SBS, SIS, SIBS, SEBS, or SEPS block copolymers can be used in the compositions of this application, provided that they have thermoplastic elastomer properties.

[0052] Preferably, the composition contains SBS, SIBS, and / or SIS block copolymers as component (c). In particular, linear SBS block copolymers, linear SIBS block copolymers, and / or linear SIS block copolymers are more preferred.

[0053] Examples of commercially available products of component (c) include, but are not limited to, Kraton D series such as Kraton D1155ES and Kraton MD1156 from Kraton, Kraton G series, Tufprene series such as Tufprene A, Asaprene T series, Taftec series and SOE series from AsahiKASEI.

[0054] The thermoplastic elastomer (c), together with the high-Tg (meth)acrylate (a-1) and the bismaleimide compound (b), plays a crucial role in achieving the beneficial effects of the resulting bond, particularly in high-temperature resistance and impact resistance. In other words, their combination is key to producing the beneficial technical effects, and their importance cannot be assessed individually. Therefore, when one prior art discloses a combination of a high-Tg (meth)acrylate and a bismaleimide, while another prior art discloses the use of SBS, SIS, SIBS, SEBS, or SEPS block copolymers, it is difficult for someone skilled in the art to foresee that the combination of these three could simultaneously improve high-temperature resistance and impact resistance.

[0055] The content of component (c) in the composition may be 1-40 wt%, preferably 5 to 35 wt%, for example 7 wt%, 10 wt%, 12 wt%, 15 wt%, 17 wt%, 20 wt%, 23 wt%, 25 wt%, 27 wt%, 30 wt%, 33 wt%, 35 wt%, 37 wt%, or any range between the two figures above, based on the total weight of the composition.

[0056] Component (d): Curing initiator In order to initiate the curing reaction, this application must contain a curing initiator, preferably selected from peroxides.

[0057] Any peroxide conventionally used in the art may be used in the compositions of this application. For example, those mentioned include, but are not limited to, cumene hydroperoxide (CHP), p-menthane hydroperoxide, tert-amyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butyl hydroperoxide (TBH), tert-butyl perbenzoate, benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene, diacetyl peroxide, butyl 4,4-bis(tert-butylperoxy)valerate, p-chlorobenzoyl peroxide, cumene hydroperoxide, tert-butyl cumene peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, dicumene peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhex-3-yne, 4-methyl-2,2-di-tert-butylperoxypentane, and combinations thereof.

[0058] The amount of curing initiator used is sufficient to initiate curing without negatively impacting adhesive properties, and can be adjusted by those skilled in the art according to actual needs. For example, the content of curing initiator (d) in the composition can be 0.1-5 wt%, preferably 0.1-4 wt%, such as 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, 2.0 wt%, 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, 3.0 wt%, 3.4 wt%, 3.8 wt%, 4.0 wt%, 4.4 wt%, 4.8 wt%, or any range between the above two values, based on the total weight of the composition.

[0059] Component (e): Curing accelerator In order to achieve the beneficial effect of rapid curing time, the composition of this application must contain a curing accelerator.

[0060] This application may use any curing accelerator conventionally used in the art that can accelerate the curing speed. For example, including but not limited to saccharin, maleic acid, iron complexes, toluidines such as N,N-diethyl-p-toluidine (DE-pT) and N,N-dimethyl-o-toluidine (DM-oT), acetylphenylhydrazine (APH), and quinones such as naphthoquinone and anthraquinone.

[0061] The amount of curing accelerator is sufficient to accelerate the curing speed without negatively affecting the adhesive properties, and can be adjusted by those skilled in the art as needed. For example, the content of curing accelerator (e) in the composition can be 0.01-5 wt%, preferably 0.1-4 wt%, such as 0.02 wt%, 0.04 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, 2.0 wt%, 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, 3.0 wt%, 3.4 wt%, 3.8 wt%, 4.0 wt%, 4.4 wt%, 4.8 wt%, or any range between the above two values, based on the total weight of the composition.

[0062] Component (f): Optional additives In addition to components (a) to (e) described above, the compositions of this application may optionally contain one or more additives that are conventionally available in the art.

[0063] Examples of additives include, but are not limited to, fillers; stabilizers; adhesion promoters; liquid polydiene polymers; and crosslinking agents.

[0064] Packing material (f-1) The compositions of the present invention may optionally contain one or more fillers. Various fillers may be used alone or in combination; for example, fillers may be used to adjust the viscosity of the composition, or fillers capable of imparting thixotropy may be used.

[0065] Exemplary fillers include, but are not limited to, silica, such as that available from Evonik under the trade name Aerosil series.

[0066] The total amount of filler should not prevent the composition from being easily coated onto a substrate by the selected method, and those skilled in the art can adjust it according to actual needs. If filler is present, its content in the composition of the present invention can be 0.1-5% by weight, preferably 0.5-4% by weight, for example 0.2% by weight, 0.4% by weight, 0.6% by weight, 0.8% by weight, 1.0% by weight, 1.2% by weight, 1.4% by weight, 1.6% by weight, 1.8% by weight, 2.0% by weight, 2.2% by weight, 2.4% by weight, 2.6% by weight, 2.8% by weight, 3.0% by weight, 3.4% by weight, 3.8% by weight, 4.0% by weight, 4.4% by weight, 4.8% by weight, each content based on the weight of the composition.

[0067] Stabilizer (f-2) As used herein, the term "stabilizer" refers to a substance that can stabilize a composition to prevent undesirable reactions.

[0068] Stabilizers available in this application include antioxidants and chelating agents.

[0069] Examples of antioxidants include, but are not limited to, sterically hindered phenols such as BHT (di-tert-butylhydroxytoluene) and phosphorus antioxidants, p-benzoquinone, 1,4-naphthoquinone, and hydroxyethanediphosphonic acid.

[0070] Chelating agents can capture metallic contaminants present in the composition, examples of which include, but are not limited to, tetrasodium EDTA (ethylenediaminetetraacetic acid) and trisodium HEDTA.

[0071] The total amount of stabilizer can be adjusted by those skilled in the art according to actual needs. If present, the stabilizer content in the composition of the present invention can be 0.01-2 wt%, preferably 0.02-1 wt%, for example 0.02 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.13 wt%, 0.15 wt%, 0.18 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, each content based on the weight of the composition.

[0072] Adhesion accelerator (f-3) To achieve better adhesive properties, adhesion promoters can be introduced. Examples of adhesion promoters include, but are not limited to, acrylic acid, methacrylic acid, bis[2-(methacryloyloxy)ethyl]phosphate, methacryloyloxyethyl maleate, bis[3-(triethoxysilyl)propyl]tetrasulfide, hydroxyethyl methacrylate, 3-methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, etc.

[0073] Preferably, the adhesion promoter has a high Tg, for example, not less than 80°C, more preferably not less than 95°C, and more preferably not less than 100°C. In particular, the Tg value of the adhesion promoter falls within the range defined by the above-mentioned component (a-1): high Tg (meth)acrylate monomer.

[0074] Those skilled in the art can adjust the total amount of adhesion promoter according to actual needs. If present, the content of adhesion promoter in the composition of the present invention can be 0.1-25% by weight, preferably 8-20% by weight, for example 1% by weight, 5% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 14% by weight, 16% by weight, 18% by weight, 20% by weight, 22% by weight, and 24% by weight, each content based on the weight of the composition.

[0075] Liquid polydiene polymer (f-4) The composition may optionally contain a liquid polydiene polymer, which helps to impart good impact resistance and also helps to shorten the setting time of the adhesive and adjust the viscosity of the composition. However, this component (f-4) is not required and can be removed or omitted.

[0076] Liquid polydiene polymers may optionally contain functional groups, such as (meth)acrylated polydiene polymers. Examples of liquid polydiene polymers include, but are not limited to, (functionalized, especially (meth)acrylated) liquid butadiene rubber and (functionalized, especially (meth)acrylated) liquid isoprene rubber. Examples of commercially available products include Huntsman's Hypro 2000X168 VTB, Sartomer's Sartomer CN307 and Sartomer CN303, and Evonik's Polyvest MAT.

[0077] Those skilled in the art can adjust the total amount of liquid polydiene polymer (f-4) according to actual needs. If present, the content of liquid polydiene polymer in the composition of the present invention can be 0.1-25% by weight, preferably 8-20% by weight, for example 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 14% by weight, 16% by weight, 18% by weight, 20% by weight, 22% by weight, and 24% by weight, each content based on the weight of the composition.

[0078] On the other hand, this application also provides a method for bonding a substrate using the composition of this application, the method comprising or consisting of the following steps: (i) Applying a primer to one or two substrates, preferably, the primer contains organic amines and active metals. (ii) Apply the composition to a primer-coated surface of a substrate or an unprimed surface of another substrate. (iii) Pair the two substrates together and press them together so that the primer and the composition come into contact with each other and cure them.

[0079] In step (i), a primer is first applied to the substrate to be bonded. There are no particular limitations on the primer, as long as it is conventionally used in the art. Typically, the primer contains organic amines and active metals that can act as curing accelerators. Examples of organic amines include, but are not limited to, dihydrophenylpyridine and tributylamine. Examples of active metals include, but are not limited to, copper-based active metals such as copper carbonate, copper acetylacetonate (II), disodium copper ethylenediaminetetraacetate (EDTA·2Na·Cu(II)), copper ethylhexanoate (II), copper naphthenate; cobalt naphthenate (II); silver nitrate; vanadium acetylacetonate (III); and iron-based active metals such as ferric naphthenate (II), ferric acetate (II), and combinations thereof. Primers available in this application include solvent-based and solvent-free primers. Commercially available primer products include, but are not limited to, Henkel's Loctite SF 7380, Loctite SF 7387, and Loctite AAA-534R.

[0080] After applying the primer, in step (ii), the composition of this application may be applied to another substrate to be bonded, or to the primer-coated surface of the substrate, so that the primer and the composition of this application can come into contact with each other.

[0081] In step (iii), the two substrates are paired and pressed together to allow the composition to cure.

[0082] There are no particular limitations on the substrates that can be bonded by the compositions of this application, and examples include, but are not limited to, plastics, ceramics, metals such as steel, brass, aluminum, zinc, iron; metal alloys; and magnetic materials such as magnets in electric motors.

[0083] In particular, the composition of this application can be used to bond magnets to electric motors. From Figures 1A to 2C As can be seen, the magnet is bonded to the stator or rotor of the electric motor by the composition of this application.

[0084] Example The present invention will now be described through the following embodiments. These embodiments are intended to help those skilled in the art better understand and practice the invention. The scope of the invention is not limited by the embodiments, but is defined by the appended claims. Unless otherwise stated, all parts and percentages are based on weight. In all embodiments, the same names refer to the same substances.

[0085] Formulation of the composition Mix all components together in a beaker. There are no particular restrictions on the order in which the components are added. Dissolve the components at an elevated temperature not exceeding 60°C to obtain a homogeneous mixture.

[0086] Taking Example 5 as an example, the composition is prepared as follows: Weigh the solid components, including BHT, saccharin, and maleic acid, and add them to a glass beaker. Add ethoxylated bisphenol A dimethacrylate and cyclohexyl methacrylate monomers to the beaker, followed by methacrylic acid. Add a stir bar to the mixture and cover the beaker while heating. Monitor the solution temperature and maintain it below 60°C. After the solid components dissolve, allow the solution to cool to room temperature, then add the thermoplastic elastomer Kraton D1155 ES and shake the mixture overnight on a laboratory shaker. After the thermoplastic elastomer dissolves, add Hypro 2000X168, Matrimid 5292, and tricyclodecanediethanol diacrylate, and mix the mixture in a high-speed mixer until a homogeneous product is obtained (1800 rpm for 3 minutes). Finally, add the Trigonox C initiator and mix the binder again in a high-speed mixer (1800 rpm for 3 minutes) to obtain a ready-to-use binder.

[0087] Methods for testing adhesive strength at room temperature and 180°C: The lap shear strength of the bond was tested according to ISO 4587 (Adhesives—Determination of tensile lap shear strength of high-strength adhesive bonds).

[0088] The isopropyl alcohol-cleaned specimens for assembly were prepared by applying a primer (Loctite SF 7387, from Henkel) to the bonding area (12.7 mm x 12.7 mm) using a brush. Adhesive was applied and covered the bonding area using a wooden scraper. The specimens, coated with the appropriate primer and adhesive, were then assembled and clamped using a Hargrave No. 1 clamp. The adhesive between the assembled specimens was allowed to cure at room temperature for 24 hours. The load at failure was determined using an Instron testing machine equipped with a 50 kN force sensor. The bonded assembly was stretched at a beam speed of 2 mm / min.

[0089] For samples tested at 180°C, the components were conditioned in an oven at 180°C for 1 hour, and then tested at the same temperature using the method described above.

[0090] Evaluation criteria for adhesive strength: 180℃ lap shear strength: - Below 650 psi, marked as bad. - Not less than 650 psi but less than 800 psi, marked as good. - Not less than 800 psi but less than 1000 psi, marked as very good. - Not less than 1000 psi, marked as excellent.

[0091] Room temperature lap shear strength: - Not less than 1500 psi but less than 1900 psi, marked as good. - Not less than 1900 psi, marked as excellent.

[0092] Fixed-time testing method Clean the test specimen with isopropyl alcohol. Apply primer (Loctite SF 7387, from Henkel) to the area to be bonded (12.7 mm x 12.7 mm) using a brush. Apply adhesive to and cover the bonding area using a wooden scraper. Then assemble the specimens with the appropriate primer and adhesive and clamp them with a Hargrave No. 1 clamp. Start the timer. Attach the 3.0 kg weight assembly to the test specimen assembly. Hold the test specimen and slowly lift it so that the weight assembly is approximately 50 to 75 mm from the working surface, ensuring that the load is parallel to the long axis of the test specimen. If the test assembly can support the weight assembly for 5 seconds, the test assembly is considered to be fixed. Record the time required for a successful test; otherwise, test at longer intervals until three consecutive replicas are fixed at a given interval.

[0093] Evaluation criteria for fixed time periods: - If it lasts longer than 5 minutes, mark it as bad. - Not exceeding 5 minutes but exceeding 2 minutes, marked as good. - No more than 2 minutes, marked as excellent.

[0094] Impact resistance test method Clean the specimen with isopropyl alcohol. Apply primer (Loctite SF 7387, from Henkel) to the area to be bonded (12.7 mm x 12.7 mm) using a brush. Apply adhesive to and cover the bonding area with a wooden scraper. Then assemble the specimens with the appropriate primer and adhesive, and clamp them with a Hargrave No. 1 clamp. Allow the adhesive between the assembled specimens to cure at room temperature for 24 hours. Test the specimens using a Loctite pendulum impact tester. Place the specimen on the support at the bottom of the clamp, ensuring the impact point is aligned with the center line of the impact head's stroke. The specimen surface should be perpendicular to the stroke line, and the specimen should firmly abut against the specimen support block. Raise the impact head to the predetermined height (90 degrees) and set the safety lock pin. After the safety lock is released, record the number of joules of energy absorbed during the test.

[0095] Impact resistance evaluation criteria: - No more than 3 J, marked as unacceptable - Over 3 J, marked as good.

[0096] Examples 1-2 (E1 and E2) and Comparative Example 1 (CE1) Each composition was formulated using the amounts listed in Table 1 below according to the above method, and its performance was tested according to the above method.

[0097] Table 1:

[0098] #1 SR297 is a product of Sartamomer, with the chemical name 1,3-butanediol dimethacrylate and a Tg of 85℃. #2 HVA-2 is a BMI with the following structure: #3 Matrimid 5292 A is a BMI with the following structure: #4 Kraton D1155 ES is a linear SBS block copolymer from Kraton, and is a thermoplastic elastomer. #5 Trigonox C is a peroxide initiator, chemically known as tert-butyl peroxide. #6 Hydroxyethane diphosphonic acid is a phosphorus-based antioxidant. #7 Aerosil 200 is fumed silica from Evonik, used as a filler. #8 MS refers to low carbon steel.

[0099] As can be seen from Table 1, compositions E1 and E2 of the present invention exhibit very good or excellent high-temperature bonding properties and good or excellent room-temperature bonding properties; however, when the composition does not contain BMI, the high-temperature bonding properties are poor.

[0100] Examples 3-4 (E3-E4) and Comparative Examples 2-6 (CE2-CE6) Each composition was formulated using the amounts listed in Table 2 below according to the above method, and its performance was tested according to the above method.

[0101] Table 2:

[0102] #9 Tufprene A is a linear SBS block copolymer from AsahiKASEI and is a thermoplastic elastomer. #10The polyurethane resin is a thermoplastic elastomer, CN971A80, from Sartomer. #11 The iron complex is from Borchers' Iron Hex-Cem. #12 Hypro 2000X168 is a low molecular weight, methacrylate-functionalized liquid polybutadiene from Huntsman.

[0103] Comparing CE2 and CE3, or CE4 and E3, reveals that high-temperature adhesive strength deteriorates when BMI is not added to the composition. Comparing CE3 and E3, or CE1 and CE2, shows that both high-temperature and room-temperature adhesive strength deteriorate when the content of low-Tg (meth)acrylate monomer (a-O) is too high. Comparing CE4 and CE5, shows that high-temperature adhesive strength deteriorates when polyurethane resin is added as a thermoplastic elastomer. CE6 indicates that high-temperature adhesive strength is poor without component (c) (SBS block copolymer).

[0104] Example 5-11 (E5-E11) Each composition was prepared using the amounts listed in Table 3 below according to the above method, and its performance was tested according to the above method.

[0105] Table 3:

[0106] #14 Polyvest MAT is a methacrylate-functionalized liquid polybutadiene from Evonik. #15 GBMS is a low-carbon steel that has undergone sandblasting treatment.

[0107] When the components and their amounts are within the scope of this application, excellent adhesive strength can be obtained at both room temperature and high temperature, along with excellent setting time (not exceeding 1 minute). In addition, good impact resistance is also achieved.

[0108] While some preferred embodiments have been described, various modifications and variations are possible based on the foregoing teachings. Therefore, it should be understood that the invention can be practiced in ways different from those specifically described without departing from the scope of the appended claims.

Claims

1. A (meth)acrylate-based adhesive composition for a two-step adhesive system, said composition comprising: (a) A (meth)acrylate component, comprising: (a-1) A high Tg (meth)acrylate monomer with a glass transition temperature (Tg) of not less than 80°C, preferably not less than 95°C, and more preferably not less than 100°C; (b) Bismaleimide compounds of formula (I): Wherein R is a substituted or unsubstituted arylene; a substituted or unsubstituted alkylene; or a combination of a substituted or unsubstituted arylene and a substituted or unsubstituted alkylene, optionally interrupted by O or S; (c) Thermoplastic elastomers selected from SBS, SIS, SIBS, SEBS, and SEPS block copolymers; (d) Curing initiators selected from peroxides, and (e) Curing accelerators, and (f) Additives that are optional.

2. The composition according to claim 1, wherein... - Based on the total weight of the composition, the content of the (meth)acrylate component (a) is 31-85% by weight, preferably 40-70% by weight, and / or - Based on the total weight of the composition, the content of the high Tg (meth)acrylate monomer (a-1) is 30 to 70% by weight, preferably 40 to 60% by weight.

3. The composition according to claim 1 or 2, wherein the content of the low Tg (meth)acrylate monomer (a-O) with a glass transition temperature below 80°C is less than 15% by weight, preferably less than 10% by weight.

4. The composition according to any one of claims 1 to 3, wherein the content of the bismaleimide compound (b) is 3-30% by weight, preferably 6-20% by weight, based on the total weight of the composition.

5. The composition according to any one of claims 1 to 4, wherein the content of the thermoplastic elastomer (c) is 1-40% by weight, preferably 5-35% by weight, based on the total weight of the composition.

6. The composition according to any one of claims 1 to 5, wherein the high Tg (meth)acrylate monomer (a-1) is selected from 3,3,5-trimethylcyclohexyl methacrylate, ethoxylated (2) bisphenol A dimethacrylate, dicyclopentyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentenyl methacrylate, tricyclodecanediethanol diacrylate, methyl 2-(allyloxymethyl)acrylate, isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentenyl acrylate, 4-tert-butylcyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, N-[3-(dimethylamino)propyl]methacrylamide, 1,3-butanediol dimethacrylate, or combinations thereof.

7. The composition according to any one of claims 1 to 6, wherein the group R in formula (I) represents: - Substituted or unsubstituted phenylene, - Substituted or unsubstituted phenylene-alkylene-phenylene, - Substituted or unsubstituted biphenylene-alkylene-biphenylene, or - Substituted or unsubstituted phenylene-O-phenylene-alkylene-phenylene-O-phenylene.

8. The composition according to any one of claims 1 to 7, wherein the bismaleimide compound (b) is selected from: in R' is a straight-chain or branched C1-C5 alkylene group, preferably methylene, ethylene, propylene and its isomers, butylene and its isomers, and more preferably methylene. R1 and R2 independently represent hydrogen, straight-chain or branched C1-C5 alkyl groups, preferably hydrogen, alkyl, ethyl, propyl and their isomers, butyl and their isomers, and more preferably hydrogen.

9. The composition according to any one of claims 1 to 8, wherein the bismaleimide compound (b) is selected from: 。 10. The composition according to any one of claims 1 to 9, wherein the peroxide (d) is selected from cumene hydroperoxide (CHP), p-menthane hydroperoxide, tert-amyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butyl hydroperoxide (TBH), tert-butyl perbenzoate, benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene, diacetyl peroxide, butyl 4,4-bis(tert-butylperoxy)valerate, p-chlorobenzoyl peroxide, cumene hydroperoxide, tert-butylcumyl peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhexyl-3-yne, 4-methyl-2,2-di-tert-butylperoxypentane, and combinations thereof.

11. The composition according to any one of claims 1 to 10, wherein the curing accelerator (e) is selected from saccharin, maleic acid, iron complexes, toluidines such as N,N-diethyl-p-toluidine (DE-pT) and N,N-dimethyl-o-toluidine (DM-oT), acetylphenylhydrazine (APH), and quinones such as naphthoquinone and anthraquinone.

12. The composition according to any one of claims 1 to 11, wherein the additive is selected from fillers, stabilizers, adhesion promoters, liquid polydiene polymers, and crosslinking agents.

13. The composition according to claim 12, wherein - The filler is selected from silica, and its preferred content is 0.1-5% by weight, more preferably 0.5-4% by weight, based on the total weight of the composition, and / or - The stabilizer is selected from antioxidants, curing inhibitors, and chelating agents, and its preferred content is 0.01-2% by weight, more preferably 0.02-1% by weight, based on the total weight of the composition, and / or - The adhesion promoter is selected from methacrylic acid and acrylic acid, and its preferred content is 0.1-25% by weight, more preferably 8-20% by weight, based on the total weight of the composition, and / or - The liquid polydiene polymer is selected from optionally functionalized liquid butadiene rubber and optionally functionalized liquid isoprene rubber, and its content is preferably 0.1-25% by weight, more preferably 8-20% by weight, based on the total weight of the composition.

14. The composition according to any one of claims 1 to 13, wherein the composition comprises: - 31-70% by weight, preferably 40-60% by weight of the (meth)acrylate component (a), - 3-30% by weight, preferably 6-20% by weight of the bismaleimide compound (b), - 1-40% by weight, preferably 5-35% by weight of the thermoplastic elastomer (c), - 0.1-5% by weight, preferably 0.1-4% by weight of the curing initiator (d), - 0.01-5% by weight, preferably 0.1-4% by weight of the curing accelerator (e), - 0-35% by weight, preferably 8-30% by weight of the additive(f), All weight percentages are based on the total weight of the composition and total 100%.

15. The composition according to any one of claims 1 to 14, wherein the lap shear strength of the cured composition after curing at room temperature for 24 hours, as determined according to ISO 4587 at 180°C, is greater than 650 psi, even greater than 800 psi, even greater than 1000 psi, and / or The fixation time for the composition shall not exceed 5 minutes, or even 2 minutes.

16. A cured product obtained from the composition of any one of claims 1 to 15.

17. An article comprising the cured product of claim 16 or an article assembled using the composition of any one of claims 1 to 15, for example, the article being an electric motor.

18. A method for bonding a substrate with the composition according to any one of claims 1 to 15, comprising: (i) Applying a primer to one or two substrates, preferably, the primer comprising an organic amine and an active metal. (ii) Apply the composition to a primer-coated surface of a substrate or an unprimed surface of another substrate. (iii) The two substrates are fitted together and pressed together to bring the primer and the composition into contact, and then cured.

19. The method of claim 18, wherein the substrate is selected from plastics, ceramics, metals (such as steel, brass, aluminum, zinc, iron); metal alloys; and magnetic materials (such as magnets in electric motors).

20. The method according to claim 18 or 19, wherein - The amine is selected from dihydrophenylpyridine; and / or - The active metal is selected from copper-based active metals, such as copper carbonate, copper acetylacetonate (II), disodium copper ethylenediaminetetraacetate (EDTA·2Na·Cu(II)), copper ethylhexanoate (II), copper naphthenate; cobalt naphthenate (II); silver nitrate; vanadium acetylacetonate (III); iron-based active metals, such as iron naphthenate (II), iron acetate (II), and combinations thereof.

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