Composition, article and motor

Abstract

A composition containing a polymerizable monomer (A) and an elastomer (B), in which the polymerizable monomer (A) contains a monofunctional (meth) acrylate (A1) and a highly polar monomer (A2), and the glass transition temperature of a cured product obtained by curing the composition at 23 DEG C for 24 hours as determined by dynamic viscoelasticity measurement is 180 DEG C or higher.

Description

Technical Field

[0001] The present invention relates to a composition, an article and a motor. Background Art

[0002] For example, demand for in-vehicle motors used to drive the wheels of electric and hybrid vehicles is growing. Adhesives are used to secure magnets in motors. Adhesives are used, for example, to bond rotors to magnets or motor stators to magnets.

[0003] As technologies related to adhesives for motors or adhesives for automobiles, for example, the technologies described in the following Patent Documents 1 to 3 can be cited.

[0004] Patent Document 1 describes a radical-curable resin composition, the purpose of which is to provide a cured product having excellent adhesion to metal parts such as magnets and free of cracks or peeling even after the thermal cycling test required for automotive parts. The radical-curable resin composition is characterized by comprising: (A) a vinyl polymer having a terminal (meth)acrylic acid group; (B) a radical-polymerizable monomer selected from the group consisting of isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate, acryloylmorpholine, dimethylacrylamide, and diethylacrylamide; (C) a (meth)acrylate or (meth)acrylic acid having a phosphate group; and (D) a radical initiator, wherein the amount of component (B) is 5 to 140 parts by mass based on 100 parts by mass of component (A).

[0005] Patent Document 2 describes a composition containing the following (A) to (D), which is intended for use as an adhesive for use in automobile manufacturing.

[0006] (A) urethane (meth)acrylate having a number average molecular weight of 5000 or more, 40 to 75 parts by mass relative to 100 parts by mass of the total of (A) and (B)

[0007] (B) a (meth)acrylic compound comprising (B-1) a (meth)acrylate having no urethane bond and (B-2) 15 to 25 parts by mass of a (meth)acrylic compound relative to 100 parts by mass of the total of (A) and (B)

[0008] (C) Polymerization initiator

[0009] (D) Reducing agent

[0010] Patent Document 3 describes a two-component adhesive with high heat and moisture resistance that can be used as a structural adhesive. The adhesive comprises a first component containing a free radical initiator and a second component containing a reducing agent. The two-component adhesive comprises a first monomer, methyl methacrylate, and a second monomer selected from the group consisting of methacrylic acid, polyfunctional (meth)acrylic acid adducts of aromatic polyols or their derivatives, and combinations thereof. The cured product of this two-component adhesive exhibits a lap shear strength of 20 MPa or greater at 25°C and 7 MPa or greater at 120°C, an adhesion strength of 2 kN / m or greater based on a T-peel test at 25°C, and a glass transition temperature of 130°C or greater.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-186439

[0014] Patent Document 2: International Publication No. 2020 / 100832

[0015] Patent Document 3: Japanese Patent Application Laid-Open No. 2016-155892 Summary of the Invention

[0016] For example, in order to cope with the higher temperatures in the operating environment caused by the miniaturization and higher output of motors, adhesives used in motors are required to have thermal fatigue resistance that can withstand tensile forces caused by centrifugal forces applied in high-temperature environments.

[0017] The present invention has been made in view of the above circumstances, and provides a composition having improved thermal fatigue resistance, and an article and a motor using the composition.

[0018] The present inventors have conducted intensive research to address the above-mentioned issues. As a result, they discovered that by setting the glass transition temperature of a cured product of a composition comprising a polymerizable monomer containing a monofunctional (meth)acrylate and a highly polar monomer within a specific range, the thermal fatigue resistance of the composition can be improved. This led to the completion of the present invention.

[0019] According to the present invention, the following compositions, articles, and motors are provided. [1]

[0021] A composition comprising a polymerizable monomer (A) and an elastomer (B), wherein:

[0022] The polymerizable monomer (A) comprises a monofunctional (meth)acrylate (A1) and a highly polar monomer (A2),

[0023] The glass transition temperature of a cured product obtained by curing the composition at 23° C. for 24 hours, as determined by dynamic viscoelasticity measurement, is 180° C. or higher. [2]

[0025] The composition according to [1], wherein

[0026] The composition is cured at 23°C for 24 hours. The elongation at break of a 1BA type dumbbell test piece described in Appendix A of JIS K 7161-2:2014 measured at 23°C and a tensile speed of 10 mm / min in accordance with JIS K 7161-2:2014 is 30% or more. [3]

[0028] The composition according to [1] or [2], wherein

[0029] The monofunctional (meth)acrylate (A1) includes a tricyclic monofunctional (meth)acrylate in which three rings are alicyclic. [4]

[0031] The composition according to [3], wherein

[0032] The tricyclic monofunctional (meth)acrylate includes one or more selected from the group consisting of a monofunctional (meth)acrylate having a structure including a dicyclopentane skeleton and one ring connected to the dicyclopentane skeleton and a monofunctional (meth)acrylate having a dicyclopentadiene skeleton. [5]

[0034] The composition according to any one of [1] to [4], wherein

[0035] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the monofunctional (meth)acrylate (A1) is 1 part by mass or more and 50 parts by mass or less. [6]

[0037] The composition according to any one of [1] to [5], wherein

[0038] The polymerizable monomer (A) further includes a multifunctional (meth)acrylate (A3). [7]

[0040] The composition according to [6], wherein

[0041] The polyfunctional (meth)acrylate (A3) includes one or more selected from the group consisting of polyfunctional (meth)acrylates having an alicyclic structure, polyfunctional (meth)acrylates having an aromatic ring structure, and polyfunctional (meth)acrylates having an aliphatic chain structure. [8]

[0043] The composition according to [6] or [7], wherein

[0044] The polyfunctional (meth)acrylate (A3) contains 2 or more and 6 or less (meth)acryloyl groups. [9]

[0046] The composition according to any one of [6] to [8], wherein

[0047] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the polyfunctional (meth)acrylate (A3) is 1 part by mass or more and 30 parts by mass or less.

[10]

[0049] The composition according to any one of [1] to [9], wherein

[0050] The highly polar monomer (A2) includes (meth)acrylic acid.

[11]

[0052] The composition according to any one of [1] to

[10] , wherein

[0053] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the highly polar monomer (A2) is 15 parts by mass or more and 40 parts by mass or less.

[12]

[0055] The composition according to any one of [1] to

[11] , wherein

[0056] The elastomer (B) includes one or more selected from the group consisting of (meth)acrylonitrile-butadiene rubber, methyl (meth)acrylate-butadiene-styrene rubber, and methyl (meth)acrylate-butadiene-(meth)acrylonitrile-styrene rubber.

[13]

[0058] The composition according to any one of [1] to

[12] , wherein

[0059] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the elastomer (B) is 20 parts by mass or more and 70 parts by mass or less.

[14]

[0061] The composition according to any one of [1] to

[13] , which is an adhesive composition.

[15]

[0063] The composition according to any one of [1] to

[14] , which is used for a motor.

[16]

[0065] The composition according to item 15 is used for fixing between the magnet and the rotor or between the magnet and the stator in the motor.

[17]

[0067] An article comprising a cured product composed of the composition according to any one of [1] to

[16] .

[18]

[0069] A motor comprising a cured product comprising the composition according to any one of [1] to

[16] .

[0070] According to the present invention, a composition having improved thermal fatigue resistance, and an article and a motor using the composition can be provided. DETAILED DESCRIPTION

[0071] Hereinafter, embodiments of the present invention will be described in detail.

[0072] In this specification, the expression "X to Y" in describing a numerical range, unless otherwise specified, means greater than or equal to X and less than or equal to Y. For example, "1 to 5 mass %" means "1 mass % or more and 5 mass % or less."

[0073] In the present specification, when the composition is a two-dose form of a first dose and a second dose, the content of each component preferably represents the content relative to the total of the first dose and the second dose.

[0074] In the present specification, the term "group" (atomic group) includes both groups without substitution and groups with substitution, even if the term "group" does not specify whether the group is substituted or unsubstituted. For example, "alkyl" includes not only alkyl groups without substitution (unsubstituted alkyl groups) but also alkyl groups with substitution (substituted alkyl groups).

[0075] The term "(meth)acrylic acid" in this specification is a concept encompassing both acrylic acid and methacrylic acid. The same applies to similar terms such as "(meth)acrylate".

[0076] The term "organic group" in this specification, unless otherwise specified, refers to an atomic group formed by removing one or more hydrogen atoms from an organic compound. For example, a "monovalent organic group" refers to an atomic group formed by removing one hydrogen atom from any organic compound.

[0077] [Adhesive composition]

[0078] Hereinafter, the “adhesive composition” in the composition of this embodiment will be described in detail.

[0079] The adhesive composition of this embodiment includes a polymerizable monomer (A) and an elastomer (B), wherein the polymerizable monomer (A) includes a monofunctional (meth)acrylate (A1) and a highly polar monomer (A2), and the glass transition temperature of a cured product obtained by curing the composition at 23°C for 24 hours, as determined by dynamic viscoelasticity measurement, is 180°C or higher.

[0080] For example, in order to cope with the higher temperatures in the operating environment caused by the miniaturization and higher output of motors, adhesives used in motors are required to have thermal fatigue resistance that can withstand tensile forces caused by centrifugal forces applied in high-temperature environments.

[0081] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that the glass transition temperature of the cured product of the adhesive composition of the present embodiment is effective as a design indicator for improving thermal fatigue resistance.

[0082] Based on the above findings, the present inventors conducted further intensive studies and found that by controlling the glass transition temperature of the cured product within a specific range, an adhesive composition having improved thermal fatigue resistance, and an article and a motor using the adhesive composition can be obtained.

[0083] That is, according to the adhesive composition of this embodiment, it is possible to realize an article and a motor having improved thermal fatigue resistance.

[0084] Furthermore, the present inventors have discovered that the adhesive composition of this embodiment can achieve both thermal fatigue resistance and thermal cycle resistance. Specifically, the adhesive composition of this embodiment can also achieve an article or motor with an improved performance balance between thermal fatigue resistance and thermal cycle resistance.

[0085] In this specification, the heat fatigue resistance refers to repeated fatigue properties at high temperatures, and the heat cycle resistance refers to the adhesive strength after heat cycle treatment.

[0086] It is believed that by designing the adhesive composition of this embodiment so that the glass transition temperature of the cured product falls within a specific range, even when repeated loads are applied at high temperatures, deterioration of the cured product due to a decrease in adhesive strength or breaking strength can be suppressed. As a result, an adhesive composition with an improved performance balance between thermal fatigue resistance and thermal cycle resistance can be obtained.

[0087] In the adhesive composition of this embodiment, from the viewpoint of further improving the performance balance between thermal fatigue resistance and thermal cycle resistance, the glass transition temperature of the cured product is preferably 183°C or higher, more preferably 185°C or higher, further preferably 188°C or higher, further preferably 190°C or higher, further preferably 195°C or higher, further preferably 198°C or higher, and preferably 350°C or lower, more preferably 300°C or lower, further preferably 250°C or lower, further preferably 230°C or lower, further preferably 220°C or lower, further preferably 210°C or lower.

[0088] The glass transition temperature of the cured product of the adhesive composition of the present embodiment can be adjusted by, for example, adjusting the type or content ratio of each component contained in the adhesive composition of the present embodiment, the mixing order or mixing method of each component, and the like.

[0089] Hereinafter, each component of the adhesive composition according to the present embodiment will be described.

[0090] <Polymerizable monomer (A)>

[0091] The adhesive composition of this embodiment contains a polymerizable monomer (A). The polymerizable monomer (A) does not contain an elastomer (B) described below.

[0092] The polymerizable monomer (A) includes a monofunctional (meth)acrylate (A1) and a highly polar monomer (A2).

[0093] (Monofunctional (meth)acrylate (A1))

[0094] The monofunctional (meth)acrylate (A1) is a compound having one (meth)acryloyl group, wherein the compound corresponding to the highly polar monomer (A2) is excluded from the monofunctional (meth)acrylate (A1).

[0095] The monofunctional (meth)acrylate (A1) preferably contains a monomer represented by the following general formula (I).

[0096] CH2=CHR 1 -COO-R 2 (I)

[0097] In the general formula (I), R1 is a hydrogen atom or a methyl group, R2 It is a group containing a cyclic hydrocarbon skeleton, preferably a group containing a polycyclic cyclic hydrocarbon skeleton. 2 The included cyclic hydrocarbon skeleton is preferably an alicyclic skeleton not including an aromatic ring.

[0098] The monofunctional (meth)acrylate (A1) preferably includes a tricyclic monofunctional (meth)acrylate in which three rings are alicyclic (hereinafter also referred to as “tricyclic monofunctional (meth)acrylate”).

[0099] The tricyclic ring refers to three connected rings. The tricyclic monofunctional (meth)acrylate of this embodiment refers to a monofunctional (meth)acrylate having an alicyclic hydrocarbon group containing three connected rings. The alicyclic hydrocarbon group is preferably an unsubstituted saturated hydrocarbon group.

[0100] The tricyclic monofunctional (meth)acrylate preferably comprises one or more selected from the group consisting of monofunctional (meth)acrylates having a structure including a dicyclopentane skeleton and a ring connected to the dicyclopentane skeleton, and monofunctional (meth)acrylates having a dicyclopentadiene skeleton. It is more preferably one or more selected from the group consisting of dicyclopentyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentene (meth)acrylate. It is even more preferably dicyclopentyl (meth)acrylate. Examples of dicyclopentyl (meth)acrylates include FA-513M manufactured by Hitachi Chemical Co., Ltd.

[0101] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the monofunctional (meth)acrylate (A1) in the adhesive composition of the present embodiment is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, even more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, even more preferably 18 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less.

[0102] In the monofunctional (meth)acrylate (A1), the ratio of the tricyclic monofunctional (meth)acrylate is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 75% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass or less.

[0103] (Highly polar monomer (A2))

[0104] The highly polar monomer (A2) is, for example, a polymerizable monomer having a polar functional group and a carbon-carbon double bond. The highly polar monomer (A2) may be a monofunctional monomer (a monomer having one carbon-carbon double bond) or a polyfunctional monomer (a monomer having multiple carbon-carbon double bonds), preferably a monofunctional monomer.

[0105] From the viewpoint of further improving the interaction with parts used in automobile manufacturing, the polar functional group possessed by the highly polar monomer (A2) preferably includes one or more selected from the group consisting of a carboxyl group, a hydroxyl group and a phosphate group, more preferably includes one or more selected from the group consisting of a carboxyl group and a phosphate group, and even more preferably includes a carboxyl group.

[0106] The highly polar monomer (A2) preferably comprises one or more selected from the group consisting of (meth)acrylic acid, fumaric acid, maleic acid, fumaric anhydride, maleic anhydride, a monomer having a phosphoric acid group and a (meth)acryloyl group, and hydroxyalkyl (meth)acrylates. It more preferably comprises one or more selected from the group consisting of (meth)acrylic acid and a monomer having a phosphoric acid group and a (meth)acryloyl group. It further preferably comprises (meth)acrylic acid, and further preferably comprises methacrylic acid.

[0107] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the highly polar monomer (A2) in the adhesive composition of the present embodiment is preferably 15 parts by mass or more, more preferably 18 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 22 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 28 parts by mass or less.

[0108] (Multifunctional (meth)acrylate (A3))

[0109] The polymerizable monomer (A) may further contain a polyfunctional (meth)acrylate (A3).

[0110] The polyfunctional (meth)acrylate (A3) is a compound having two or more carbon-carbon double bonds such as (meth)acryloyl groups, etc. However, the polyfunctional (meth)acrylate (A3) is obtained by excluding the compound corresponding to the highly polar monomer (A2).

[0111] The polyfunctional (meth)acrylate (A3) preferably contains 2 or more and 6 or less (meth)acryloyl groups, more preferably contains 2 or more and 4 or less (meth)acryloyl groups, further preferably contains 2 or more and 3 or less (meth)acryloyl groups, and further preferably contains 2 (meth)acryloyl groups.

[0112] The polyfunctional (meth)acrylate (A3) preferably contains one or two or more selected from the group consisting of polyfunctional (meth)acrylates having an alicyclic structure, polyfunctional (meth)acrylates having an aromatic ring structure, and polyfunctional (meth)acrylates having an aliphatic chain structure.

[0113] Examples of the polyfunctional (meth)acrylate having an alicyclic structure include one or more selected from the group consisting of dicyclopentyl di(meth)acrylate, 1,3-adamantanedimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, dihydroxymethyl-tricyclodecane di(meth)acrylate, and dihydroxymethyl-cyclohexane di(meth)acrylate.

[0114] Examples of the polyfunctional (meth)acrylate having an aromatic ring structure include one or more selected from the group consisting of 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, ethylene oxide-added bisphenol A di(meth)acrylate (EO-BPA di(meth)acrylate), ethylene oxide-added bisphenol F di(meth)acrylate, propylene oxide-added bisphenol A di(meth)acrylate, and propylene oxide-added bisphenol F di(meth)acrylate.

[0115] Examples of the polyfunctional (meth)acrylate having an aliphatic chain structure include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and isocyanuric acid cyclopentane di(meth)acrylate. One or more selected from the group consisting of ethylene oxide-modified di(meth)acrylate, isocyanuric acid ethylene oxide-modified tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tris[(meth)acryloyloxyethyl]isocyanurate, ditrimethylolpropane tetra(meth)acrylate, dimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0116] The polyfunctional (meth)acrylate (A3) more preferably contains one or more selected from the group consisting of dicyclopentyl di(meth)acrylate, ethylene oxide-added bisphenol A di(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, and further preferably contains dicyclopentyl di(meth)acrylate.

[0117] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the multifunctional (meth)acrylate (A3) in the adhesive composition of the present embodiment is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, even more preferably 18 parts by mass or less, and even more preferably 16 parts by mass or less.

[0118] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the polymerizable monomer (A) in the adhesive composition of the present embodiment is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 38 parts by mass or more, even more preferably 40 parts by mass or more, and is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less.

[0119] <Elastomer (B)>

[0120] The adhesive composition of this embodiment contains an elastomer (B).

[0121] The elastomer (B) preferably has soft segment units. The soft segment units preferably include one or more selected from the group consisting of a diene structure, an ethylene structure, a propylene structure, an isoprene structure, a urethane structure, an ethylene glycol structure, a propylene glycol structure, a silicone structure, and a chloroprene structure, and more preferably include a diene structure such as a butadiene structure.

[0122] The elastomer (B) may have a hard segment in addition to the soft segment units. The "soft segment" refers to the soft portion that exhibits rubber elasticity. The "hard segment" refers to the molecular restriction portion that functions as a crosslinking point of the crosslinked rubber to prevent plastic deformation.

[0123] In the entire elastomer of the present embodiment, the content of the soft segment units in the elastomer (B) is preferably 15% by mass or more and 90% by mass or less, and more preferably 25% by mass or more and 85% by mass or less.

[0124] The elastomer (B) preferably comprises one or more selected from the group consisting of (meth)acrylonitrile-butadiene rubber, methyl(meth)acrylate-butadiene-styrene rubber, and methyl(meth)acrylate-butadiene-(meth)acrylonitrile-styrene rubber. It more preferably comprises one or two selected from the group consisting of (meth)acrylonitrile-butadiene rubber and methyl(meth)acrylate-butadiene-(meth)acrylonitrile-styrene rubber. It is further preferred that it comprises both (meth)acrylonitrile-butadiene rubber and methyl(meth)acrylate-butadiene-(meth)acrylonitrile-styrene rubber.

[0125] The adhesive composition of the present embodiment may include only one elastomer or more than two elastomers. For example, one or two of the groups selected from the above-mentioned methyl (meth) acrylate-butadiene-styrene rubber and methyl (meth) acrylate-butadiene-(meth) acrylonitrile-styrene rubber and (meth) acrylonitrile-butadiene rubber may be used in combination. In the case of use, the former: the latter=0.5:9.5~9.5:0.5 are preferably used in a mass ratio, the former: the latter=0.8:9.2~9.2:0.8 are more preferably used, and the former: the latter=1.0:9.0~9.0:1.0 are further preferably used.

[0126] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the elastomer (B) in the adhesive composition of the present embodiment is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, and is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, even more preferably 62 parts by mass or less, and even more preferably 60 parts by mass or less.

[0127] <Polymerization initiator (C)>

[0128] The adhesive composition of this embodiment preferably contains a polymerization initiator (C). The carbon-carbon double bond of the polymerizable monomer (A) is polymerized by the polymerization initiator (C), thereby improving the adhesiveness.

[0129] The polymerization initiator (C) preferably contains a thermal radical polymerization initiator. From the viewpoint of further improving reactivity, the thermal radical polymerization initiator preferably contains an organic peroxide, more preferably contains one or more selected from the group consisting of cumene hydroperoxide, p-menthane hydroperoxide, tert-butyl hydroperoxide, diisopropylbenzene diperoxide, methyl ethyl ketone peroxide, and tert-butyl peroxybenzoate, and even more preferably contains cumene hydroperoxide.

[0130] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the polymerization initiator (C) in the adhesive composition of the present embodiment is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, and is preferably 20.0 parts by mass or less, more preferably 15.0 parts by mass or less, even more preferably 12.0 parts by mass or less, even more preferably 10.0 parts by mass or less, even more preferably 8.0 parts by mass or less, even more preferably 6.0 parts by mass or less, even more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0131] <Reducing agent (D)>

[0132] The adhesive composition of this embodiment preferably contains a reducing agent (D).

[0133] The adhesive composition of this embodiment can further improve curability by using a polymerization initiator (C) and a reducing agent (D) in combination.

[0134] The reducing agent (D) may be any reducing agent as long as it reacts with the polymerization initiator (C) to generate radicals.

[0135] The reducing agent (D) preferably contains one or more selected from the group consisting of tertiary amines, thiourea derivatives, and transition metal salts, and more preferably contains a transition metal salt.

[0136] Examples of the tertiary amine include one or two or more selected from the group consisting of triethylamine, tripropylamine, tributylamine, and N,N-dimethyl-p-toluidine.

[0137] Examples of the thiourea derivative include one or more selected from the group consisting of 2-mercaptobenzimidazole, methylthiourea, dibutylthiourea, ethylenethiourea, acetyl-2-thiourea, benzoylthiourea, N,N-diphenylthiourea, N,N-diethylthiourea, N,N-dibutylthiourea, and tetramethylthiourea.

[0138] Examples of the transition metal salt include one or more selected from the group consisting of cobalt naphthenate, copper naphthenate, and vanadium acetylacetonate. The transition metal salt more preferably contains vanadium acetylacetonate.

[0139] When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the reducing agent (D) in the adhesive composition of the present embodiment is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.10 parts by mass or more, even more preferably 0.15 parts by mass or more, even more preferably 0.20 parts by mass or more, and is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less, even more preferably 1.0 parts by mass or less, and even more preferably 0.50 parts by mass or less.

[0140] <Other ingredients>

[0141] The adhesive composition of the present embodiment may or may not contain other components besides the above-mentioned ones.

[0142] (paraffin)

[0143] The adhesive composition of this embodiment may include paraffin wax. Various paraffin waxes can be used, for example, to rapidly solidify the portion in contact with air. Examples of the paraffin wax include one or more selected from the group consisting of paraffin wax, microcrystalline wax, carnauba wax, beeswax, lanolin, spermaceti, ozokerite, and candelilla wax.

[0144] When the adhesive composition of the present embodiment contains paraffin wax, it may contain only one type of paraffin wax, or may contain two or more types of paraffin wax.

[0145] When the adhesive composition of the present embodiment contains paraffin wax, from the viewpoint of further improving curability, when the total content of the polymerizable monomer (A) and the elastomer (B) is set to 100 parts by mass, the content of the paraffin wax in the adhesive composition of the present embodiment is preferably 0.01 parts by mass or more and 3 parts by mass or less, and more preferably 0.1 parts by mass or more and 2 parts by mass or less.

[0146] (Stabilizer)

[0147] To further enhance storage stability, the adhesive composition of this embodiment may contain various stabilizers. Examples of such stabilizers include (i) phenolic antioxidants (e.g., 2,2'-methylenebis(4-methyl-6-tert-butylphenol)), (ii) quinone compounds (e.g., p-benzoquinone, hydroquinone monomethyl ether), (iii) compounds known as polymerization inhibitors (e.g., amine-based polymerization inhibitors such as phenothiazine, citric acid), and (iv) stable free radical compounds containing stable free radicals.

[0148] When the adhesive composition of the present embodiment contains a stabilizer, from the viewpoint of suppressing a decrease in the performance of the adhesive composition and further improving storage stability, the content of the stabilizer in the adhesive composition of the present embodiment is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, even more preferably 0.05 parts by mass or more, even more preferably 0.10 parts by mass or more, and is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less, even more preferably 1.5 parts by mass or less, and even more preferably 1.0 parts by mass or less, based on the total content of the polymerizable monomer (A) and the elastomer (B) being 100 parts by mass.

[0149] <Characteristics of the Adhesive Composition>

[0150] From the viewpoint of further improving heat cycle resistance, the elongation at break of a 1BA type dumbbell test piece described in Appendix A of JIS K 7161-2: 2014, obtained by curing the adhesive composition of the present embodiment at 23°C for 24 hours, measured under the conditions of 23°C and a tensile speed of 10 mm / min in accordance with JIS K7161-2: 2014, is preferably 30% or more, more preferably 35% or more, even more preferably 38% or more, even more preferably 40% or more, even more preferably 45% or more, even more preferably 48% or more, and is preferably 100% or less.

[0151] A suitably high elongation at break of the cured adhesive composition is believed to indicate that the cured adhesive composition effectively relaxes stress generated during thermal cycle testing, etc. In particular, in bonding dissimilar components with different thermal expansion coefficients, such as a motor core and a magnet, a suitably high elongation at break of the cured adhesive composition is believed to enable effective stress relaxation.

[0152] The elongation at break of the adhesive composition of the present embodiment can be adjusted by, for example, adjusting the type or content ratio of each component contained in the adhesive composition of the present embodiment, the mixing order or mixing method of each component, and the like.

[0153] <Single-dose / Double-dose>

[0154] The adhesive composition of the present embodiment may be a single-component form or a two-component form (a form in which two components filled in different containers are mixed before use).

[0155] In the case of a two-part type, it is preferred that the polymerization initiator (C) be contained in the first part and the reducing agent (D) be contained in the second part.

[0156] When the adhesive composition of this embodiment is a two-part adhesive composition, the amounts of the components in the first and second parts are preferably adjusted so that the adhesive composition after mixing the first and second parts contains each component within the preferred content ranges described above. Furthermore, the various properties of the adhesive composition described in this specification relate to the adhesive composition after mixing the first and second parts.

[0157] <Method for producing adhesive composition>

[0158] When producing the adhesive composition of the present embodiment, it is preferable to appropriately adjust the mixing order and mixing method of the components rather than simply mixing the components.

[0159] When manufacturing the adhesive composition of the present embodiment, it is particularly preferred that the polymerizable monomer (A) and the elastomer (B) are fully mixed. Therefore, as shown in the examples described below, it is preferred that the following be performed: (i) first, at least a portion of the polymerizable monomer (A) and at least a portion of the elastomer (B) are fully and uniformly mixed at 50 to 80° C. to form a mixture, and (ii) then, other components are added to the mixture and stirred. It is believed that in this way, the polymerizable monomer (A) and the elastomer (B) are fully and uniformly mixed. The adhesive composition manufactured in this way tends to easily meet the characteristics of the above-mentioned adhesive composition (elongation at break, glass transition temperature of the cured product, etc.) compared to adhesive compositions obtained by other manufacturing methods.

[0160] <Application>

[0161] The adhesive composition of this embodiment can be preferably used as an automotive adhesive used in the manufacture of automobiles, more preferably as a motor adhesive, and even more preferably as an adhesive for fixing a magnet and a rotor (rotor) or a magnet and a stator (stator) in the motor.

[0162] Items

[0163] The article of this embodiment includes a cured product composed of the adhesive composition of this embodiment.

[0164] By applying the adhesive composition of the present embodiment to an article and curing it, for example, an article including a cured product of the adhesive composition can be obtained.

[0165] The adhesive composition of this embodiment is preferably capable of curing and bonding articles even without heating (at room temperature) (especially when containing a polymerization initiator and a reducing agent). Of course, heating is not excluded when bonding articles.

[0166] Motor

[0167] The motor of the present embodiment includes a cured product composed of the adhesive composition of the present embodiment.

[0168] The motor of this embodiment includes, for example, a magnet, a rotor, and a stator, wherein a cured product composed of the adhesive composition of this embodiment is contained between at least one of the magnet and the rotor or between the magnet and the stator. In this case, it is preferred that the cured product composed of the adhesive composition of this embodiment is fixed between at least one of the magnet and the rotor or between the magnet and the stator in the motor.

[0169] Methods for securing the magnets to the rotor include, for example, securing the magnets within the rotor's slits. Furthermore, methods for securing the magnets to the stator include, for example, securing the magnets to the yoke. Examples of the magnets include ferrite magnets and permanent magnets. Examples of permanent magnets include neodymium magnets.

[0170] This specification primarily describes "adhesive compositions." However, the adhesive compositions described herein can also be used in fields other than bonding, such as coating materials or injection molding agents. In other words, the adhesive compositions described herein can also be used as compositions with unrestricted uses, curable compositions, and resin compositions. The compositions of this embodiment can also be used, for example, as so-called adhesives, sealants, photosensitive resin layers, insulating resin layers, thermally conductive resin layers, coating materials, and the like.

[0171] While the embodiments of the present invention have been described above, these are merely illustrative of the present invention, and various configurations other than those described above may be employed. Furthermore, the present invention is not limited to the aforementioned embodiments, and modifications and improvements within the scope of achieving the objectives of the present invention are encompassed within the present invention.

[0172] Example

[0173] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0174] <Examples 1 to 3 and Comparative Examples 1 to 4>

[0175] The first and second agents were prepared by thoroughly mixing the components in the proportions (unit: parts by mass) shown in Table 1 using a stirring device equipped with a stirring blade. Next, equal amounts of the first and second agents were mixed to prepare an adhesive composition. The following evaluations were performed using the resulting adhesive compositions. The results are shown in Table 1. The proportions of the components in Table 1 are all in parts by mass.

[0176] Here, in the preparation of the first and second agents, the polymerizable monomer (A) and the elastomer (B) are fully and uniformly mixed at 50 to 80° C. to form a mixture, and then other components are added to the mixture and stirred, followed by degassing, thereby preparing the first and second agents, respectively.

[0177] Hereinafter, information related to a part of what is described in Table 1 will be additionally described.

[0178] BL-20: Methyl methacrylate-butadiene-acrylonitrile-styrene rubber (methyl methacrylate content 15 mass%, butadiene content 46 mass%, acrylonitrile content 3 mass%, styrene content 36 mass%, soft segment unit content 46 mass%)

[0179] 1300X33VTBNX LC: Acrylonitrile-butadiene rubber having methacryloyl groups at both ends (acrylonitrile content 18% by mass, soft segment unit content 82% by mass)

[0180] N250SL: Acrylonitrile-butadiene rubber (acrylonitrile content 19.5% by mass, soft segment unit content 81% by mass)

[0181] DCPD type methacrylate: dicyclopentyl methacrylate

[0182] SIPOMER PAM 4000: Phosphate ester of 2-hydroxyethyl methacrylate

[0183] BPA diglycidyl ether acrylic acid adduct: Bisphenol A diglycidyl ether acrylic acid adduct

[0184] DCPD type dimethacrylate: dicyclopentyl dimethacrylate

[0185] <Evaluation>

[0186] Each of the following measurements and evaluations was performed three times, and the average of the three obtained values ​​was adopted as the result.

[0187] [Dynamic viscoelasticity (DMA) measurement]

[0188] First, a cured product (test piece) of the adhesive composition for dynamic viscoelasticity measurement was prepared. Specifically, the test piece was prepared as shown in the following (1) to (3).

[0189] (1) First, a 0.5 mm thick silicone sheet with 5×40 mm holes was placed on a PET film, and an adhesive composition was applied to the hole-forming portion to form a coating film.

[0190] (2) Another PET film was laminated onto the coated film. Then, both sides were sandwiched with 1 cm thick glass plates, and a load was applied and pressed. In this state, the film was cured for 24 hours in a room at a temperature of 23°C and a relative humidity of 50 RH%. The pressure was then released and the PET film was peeled off. A sheet-like cured product was thus obtained. The film thickness was adjusted to approximately 500 μm based on the thickness of the silicone sheet.

[0191] (3) The sheet-like cured product was cut to obtain a strip-shaped test piece having a size of 0.5×5×40 mm.

[0192] The dynamic viscoelastic properties of the obtained test pieces were measured using a dynamic viscoelasticity measuring instrument (DMS7100, manufactured by SII) at a frequency of 1.0 Hz, a tensile mode, a measurement temperature range of 0°C to 250°C, and a heating rate of 5°C / minute. Data were obtained. The peak temperature of the loss tangent (tan δ) (tan δ peak, i.e., the glass transition temperature) was determined from the temperature-loss tangent (tan δ) curve obtained from the obtained data.

[0193] [Elongation at break]

[0194] The elongation at break was measured in accordance with “Plastics—Determination of tensile properties” of JIS K7161-1: 2014 and K7161-2: 2014.

[0195] The adhesive composition was cured for 24 hours at 23°C and 50% relative humidity to produce a 1BA dumbbell-shaped test piece (1BA dumbbell test piece) as specified in Appendix A of JIS K 7161-2:2014. The resulting 1BA dumbbell test piece was then subjected to a tensile test at 23°C at a tensile speed of 10 mm / min to measure its elongation at break. The tensile testing machine used was an INSTRON 3365 (manufactured by Instron Corporation).

[0196] [Thermal fatigue resistance]

[0197] A film was formed by applying the adhesive composition (a mixture of two components for a two-component type) to one side of a test piece (25 mm × 100 mm × 1.6 mm thick cold-rolled steel sheet (JIS G 3141 SPCC-SD, manufactured by Engineering Test Service Co., Ltd.), degreased with acetone) to form a film. Another test piece (25 mm × 100 mm × 1.6 mm thick cold-rolled steel sheet (JIS G 3141 SPCC-SD, manufactured by Engineering Test Service Co., Ltd.), degreased with acetone) was directly superimposed on the film and bonded together. The pieces were then cured at room temperature (23°C) for 24 hours. This produced a test piece. Here, a polyethylene filler with a particle size of 100 μm (manufactured by Prime Polymer Co., Ltd., product name: HI-ZEX 2100JPD) was added to the adhesive composition. The polyethylene filler (thickness-adjusting spacer) acted as a film thickness-adjusting spacer to adjust the film thickness of the adhesive composition to 100 μm (= 0.1 mm). The amount of the polyethylene filler used was 0.5 parts by mass per 100 parts by mass of the polymerizable monomer (A).

[0198] Next, the obtained test piece was subjected to a tensile shear bonding test at 155°C and a tensile speed of 10 mm / min using a universal testing machine Model 5967 manufactured by Instron, and the tensile shear bonding strength F was measured. Ref(155) .

[0199] Then, using a fatigue testing machine, the obtained test piece was repeatedly loaded in an environment of 155°C, and the number of cycles until failure occurred was measured. Furthermore, multiple tests were conducted with varying loads, and the number of cycles to failure was measured. The strength F at the design life expectancy was calculated using this approximate formula. EOL(155) Then, through 100×F EOL(155) / F Ref(155) The thermal fatigue resistance was evaluated. EOL(155) / F Ref(155) The evaluation of 10% or more was A (excellent), the evaluation of 5% or more and less than 10% was B (acceptable), and the evaluation of less than 5% was C (unacceptable).

[0200] The tensile shear bond strength was measured in accordance with JIS K 6850:1999, Adhesives - Tensile shear bond strength test method for rigid adhesive materials.

[0201] [Heat cycle resistance]

[0202] First, the test piece prepared in the above [Heat Fatigue Resistance] was subjected to a tensile shear adhesion test at a temperature of 23°C and a relative humidity of 50% at a tensile speed of 10 mm / min using a universal testing machine Model 5967 manufactured by Instron. The tensile shear adhesion strength F was measured. Ref(23) .

[0203] Furthermore, the test pieces prepared in the above-mentioned [Thermal Fatigue Resistance] were subjected to a heat cycle test for 300 cycles, with one cycle consisting of "treatment in a -10°C atmosphere for 30 minutes, treatment at room temperature for 5 minutes, treatment at 150°C for 30 minutes, and further treatment at room temperature for 5 minutes."

[0204] Next, the test pieces after the heat cycle test were subjected to a tensile shear adhesion test at a temperature of 23°C and a relative humidity of 50% at a tensile speed of 10 mm / min using a universal testing machine Model 5967 manufactured by Instron. The tensile shear adhesion strength F was measured. after Then, through 100×F after / F Ref(23) The heat cycle resistance was evaluated. after / F Ref(23) A score of 40% or more was rated A (excellent), a score of 20% or more and less than 40% was rated B (acceptable), and a score of less than 20% was rated C (unacceptable).

[0205] Table 1 summarizes the compositions of the adhesive compositions and the measurement and evaluation results.

[0206] In Table 1, the unit of the amount of each component of the adhesive composition is part by mass.

[0207] [Table 1]

[0208]

[0209] The adhesive compositions of Examples 1 to 3, whose cured products had glass transition temperatures of 180°C or higher, showed improved performance balance between thermal fatigue resistance and heat cycle resistance compared to the adhesive compositions of Comparative Examples 1 to 4, whose cured products had glass transition temperatures of less than 180°C.

[0210] This application claims priority based on Japanese Patent Application No. 2023-007239 filed on January 20, 2023, the disclosure of which is incorporated herein in its entirety.

Claims

1. A composition comprising a polymerizable monomer (A) and an elastomer (B), wherein: The polymerizable monomer (A) comprises a monofunctional (meth)acrylate (A1) and a highly polar monomer (A2), The glass transition temperature of a cured product obtained by curing the composition at 23° C. for 24 hours, as determined by dynamic viscoelasticity measurement, is 180° C. or higher.

2. The composition according to claim 1, wherein The composition is cured at 23°C for 24 hours. The elongation at break of a 1BA type dumbbell test piece described in Appendix A of JIS K 7161-2:2014 measured at 23°C and a tensile speed of 10 mm / min in accordance with JIS K 7161-2:2014 is 30% or more.

3. The composition according to claim 1 or 2, wherein The monofunctional (meth)acrylate (A1) includes a tricyclic monofunctional (meth)acrylate in which three rings are alicyclic.

4. The composition according to claim 3, wherein The tricyclic monofunctional (meth)acrylate includes one or more selected from the group consisting of a monofunctional (meth)acrylate having a structure including a dicyclopentane skeleton and one ring connected to the dicyclopentane skeleton and a monofunctional (meth)acrylate having a dicyclopentadiene skeleton.

5. The composition according to claim 1 or 2, wherein When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the monofunctional (meth)acrylate (A1) is 1 part by mass or more and 50 parts by mass or less.

6. The composition according to claim 1 or 2, wherein The polymerizable monomer (A) further includes a multifunctional (meth)acrylate (A3).

7. The composition according to claim 6, wherein The polyfunctional (meth)acrylate (A3) includes one or more selected from the group consisting of polyfunctional (meth)acrylates having an alicyclic structure, polyfunctional (meth)acrylates having an aromatic ring structure, and polyfunctional (meth)acrylates having an aliphatic chain structure.

8. The composition according to claim 6, wherein The polyfunctional (meth)acrylate (A3) contains 2 or more and 6 or less (meth)acryloyl groups.

9. The composition according to claim 6, wherein When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the polyfunctional (meth)acrylate (A3) is 1 part by mass or more and 30 parts by mass or less.

10. The composition according to claim 1 or 2, wherein The highly polar monomer (A2) includes (meth)acrylic acid.

11. The composition according to claim 1 or 2, wherein When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the highly polar monomer (A2) is 15 parts by mass or more and 40 parts by mass or less.

12. The composition according to claim 1 or 2, wherein The elastomer (B) includes one or more selected from the group consisting of (meth)acrylonitrile-butadiene rubber, methyl (meth)acrylate-butadiene-styrene rubber, and methyl (meth)acrylate-butadiene-(meth)acrylonitrile-styrene rubber.

13. The composition according to claim 1 or 2, wherein When the total content of the polymerizable monomer (A) and the elastomer (B) is 100 parts by mass, the content of the elastomer (B) is 20 parts by mass or more and 70 parts by mass or less. The composition according to claim 1 or 2, which is an adhesive composition.

15. The composition according to claim 1 or 2, which is used in a motor.

16. The composition according to claim 15, which is used to fix between a magnet and a rotor or between a magnet and a stator in the motor.

17. An article comprising a cured product composed of the composition according to claim 1 or 2.

18. A motor comprising a cured product comprising the composition according to claim 1 or 2.

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