Anaerobic adhesive, cured product, bonded stack, and motor

Abstract

The present invention provides: an anaerobic adhesive which is excellent in terms of adhesiveness to an electromagnetic steel sheet and in heat resistance; a cured product of the anaerobic adhesive; a bonded stack which is obtained by stacking electromagnetic steel sheets using the anaerobic adhesive; and a motor using the bonded stack. The present invention provides: an anaerobic adhesive which contains (A) a multifunctional (meth)acrylate which contains at least one skeleton that is selected from the group consisting of a polyisoprene and a polybutadiene, (B) a multifunctional (meth)acrylate which contains an alicyclic skeleton, (C) a peroxide, and (D) an anaerobic curing catalyst; and the like.

Description

Anaerobic adhesive, cured product, adhesive laminate, and motor

[0001] The present invention relates to an anaerobic adhesive, a cured product, an adhesive laminate, and a motor.

[0002] Conventionally, laminates of stacked electromagnetic steel sheets have been used in motor cores (see, for example, Patent Documents 1 and 2). One method for laminating electromagnetic steel sheets is the crimping method. In recent years, there has been an increasing demand for higher efficiency in motor cores to save energy. Accordingly, there has been a trend toward thinner electromagnetic steel sheets used in laminated electromagnetic steel sheets to reduce eddy current loss. For reasons such as the inability to obtain sufficient joining strength through crimping when electromagnetic steel sheets are thin, adhesive lamination using an adhesive has recently attracted attention (see, for example, Patent Document 3).

[0003] JP 62-224434 A JP 2010-154589 A International Publication No. 2019 / 123885

[0004] To improve the manufacturing efficiency of motor cores, adhesives that can be cured quickly are required. Also, because motor cores may generate heat themselves or be exposed to high temperatures during the manufacturing process or in the environment in which they are used, adhesives that can be used stably in high-temperature (180°C or higher) environments after curing (hereinafter referred to as heat resistance) are required in addition to adhesive properties after curing.

[0005] Because epoxy resin compositions cannot be cured in a short time, the present inventors focused on anaerobic adhesives and first considered repurposing heat-resistant anaerobic adhesives that were conventionally used for bonding metals. However, even though the anaerobic adhesives had excellent adhesion and heat resistance to cold-rolled steel sheets (SPCC), they did not have sufficient adhesion and heat resistance to electromagnetic steel sheets.

[0006] The inventors of the present invention considered the fact that heat-resistant materials tend to have poor adhesion because they are hard and brittle, and therefore considered incorporating a compound that imparts flexibility, such as urethane acrylate, as one of the (meth)acrylate compounds that is the curing component in anaerobic adhesives, but found it difficult to achieve both adhesion and heat resistance.

[0007] Therefore, an object of the present invention is to provide an anaerobic adhesive that has excellent adhesion and heat resistance to electromagnetic steel sheets, a cured product of the anaerobic adhesive, an adhesive laminate in which electromagnetic steel sheets are laminated using the anaerobic adhesive, and a motor using the adhesive laminate.

[0008] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors discovered that an anaerobic adhesive containing two types of polyfunctional (meth)acrylates having specific structures can solve the above-mentioned problems, and thus completed the present invention.

[0009] That is, the present invention provides the following: (1) An anaerobic adhesive comprising: (A) a polyfunctional (meth)acrylate containing at least one skeleton selected from the group consisting of polyisoprene and polybutadiene, (B) a polyfunctional (meth)acrylate containing an alicyclic skeleton, (C) a peroxide, and (D) an anaerobic curing catalyst.

[0010] (2) The anaerobic adhesive according to (1), wherein the anaerobic curing catalyst (D) is at least one selected from the group consisting of aromatic amine compounds and hydrazine compounds.

[0011] (3) The anaerobic adhesive according to (1) or (2) above, further comprising (E) an aliphatic monofunctional (meth)acrylate.

[0012] (4) The anaerobic adhesive according to any one of (1) to (3), wherein the (B) polyfunctional (meth)acrylate containing an alicyclic skeleton is a polyfunctional (meth)acrylate containing a tricyclodecane skeleton.

[0013] (5) The anaerobic adhesive according to any one of (1) to (4) above, which is for laminating electromagnetic steel sheets.

[0014] (6) The anaerobic adhesive according to any one of (1) to (4) above, which is used for bonding between metals.

[0015] (7) The anaerobic adhesive according to (6), wherein the metal has an oxide film.

[0016] (8) A cured product obtained by curing the anaerobic adhesive described in (1) to (7) above.

[0017] (9) An adhesive laminate in which electromagnetic steel sheets are laminated using the anaerobic adhesive described in (1) to (7) above.

[0018] (10) A motor characterized by using the adhesive laminate described in (9) above.

[0019] The present invention makes it possible to provide an anaerobic adhesive that has excellent adhesion and heat resistance to electromagnetic steel sheets, a cured product of the anaerobic adhesive, an adhesive laminate in which electromagnetic steel sheets are laminated using the anaerobic adhesive, and a motor that uses the adhesive laminate.

[0020] The anaerobic adhesive of the present invention will be described in detail below, but the present invention is not limited to the following embodiments. Appropriate modifications and improvements to the following embodiments based on the ordinary knowledge of those skilled in the art are also within the scope of the present invention, as long as they do not deviate from the spirit of the present invention.

[0021] In this specification, the term "to" indicating a range of values ​​indicates a range that includes the values ​​stated as the upper and lower limits. When a unit is stated only for the upper limit of a range of values, this means that the lower limit is expressed in the same unit as the upper limit.

[0022] In the numerical ranges described in stages in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages.

[0023] Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0024] In this specification, the content or amount of each component in a composition means, when multiple substances corresponding to each component are present in the composition, the total content or amount of the multiple substances present in the composition, unless otherwise specified.

[0025] (Anaerobic Adhesive) The anaerobic adhesive of the present disclosure is characterized by containing (A) a polyfunctional (meth)acrylate containing at least one skeleton selected from the group consisting of polyisoprene and polybutadiene (hereinafter also referred to as "(A) polyfunctional (meth)acrylate"), (B) a polyfunctional (meth)acrylate containing an alicyclic skeleton (hereinafter also referred to as "(B) polyfunctional (meth)acrylate"), (C) a peroxide, and (D) an anaerobic curing catalyst. Note that, in this specification, "(meth)acrylate" refers to an acrylate or methacrylate. Also, in this specification, the number of (meth)acryloyl groups contained in the (meth)acrylate may be referred to as the "number of functional groups." Note that "(meth)acryloyl group" refers to an acryloyl group or a methacryloyl group.

[0026] Each component is described in detail below.

[0027] [Component (A)] The anaerobic adhesive of the present disclosure contains (A) a polyfunctional (meth)acrylate containing at least one skeleton selected from the group consisting of polyisoprene and polybutadiene. By containing (A) a polyfunctional (meth)acrylate, flexibility can be imparted to the anaerobic adhesive. The skeleton contains, in addition to the polyisoprene skeleton, a polyisoprene skeleton that is fully or partially hydrogenated. Furthermore, in addition to the polybutadiene skeleton, a polybutadiene skeleton that is fully or partially hydrogenated. One type of (A) polyfunctional (meth)acrylate may be used alone, or two or more types may be used in combination.

[0028] The polyfunctional (meth)acrylate containing a polyisoprene skeleton has a (meth)acryloyl group at the end or side chain of the polyisoprene molecule, and the (meth)acrylate containing a polybutadiene skeleton has a (meth)acryloyl group at the end or side chain of the polybutadiene molecule.

[0029] The number of (meth)acryloyl groups in the (A) polyfunctional (meth)acrylate is preferably 2 to 4, and more preferably 2 to 3. By setting the number of (meth)acryloyl groups in the range of 2 to 4, it is possible to adjust the cure shrinkage to an appropriate range.

[0030] The number average molecular weight of the (A) polyfunctional (meth)acrylate is preferably 1,000 to 60,000, more preferably 2,000 to 50,000, and even more preferably 10,000 to 40,000. By setting the number average molecular weight in the range of 1,000 to 60,000, the viscosity of the resulting anaerobic adhesive can be adjusted to an appropriate range. The number average molecular weight was measured and calculated by gel permeation chromatography using a column with a styrene-divinylbenzene-based packing material and a tetrahydrofuran eluent, and the molecular weight was calculated in terms of standard polystyrene.

[0031] Examples of (meth)acrylates containing a polyisoprene skeleton include esters of a maleic anhydride adduct of a polyisoprene polymer with 2-hydroxyethyl methacrylate (Kurapren (registered trademark) UC102M (number average molecular weight 17,000); Kurapren UC203M (number average molecular weight 35,000); Kurapren UC-1 (number average molecular weight 25,000) (all manufactured by Kuraray Co., Ltd.)).

[0032] As the (meth)acrylate containing a polybutadiene skeleton, available are 1,2-polybutadiene-terminated urethane (meth)acrylate (for example, NISSO-PB TE-2000 (number average molecular weight 2,500), manufactured by Nippon Soda Co., Ltd.), hydrogenated 1,2-polybutadiene-terminated urethane (meth)acrylate (for example, NISSO-PB TEAI-1000 (number average molecular weight 2,000), manufactured by Nippon Soda Co., Ltd.), and 1,4-polybutadiene-terminated urethane (meth)acrylate (BAC-45 (number average molecular weight 4,800), manufactured by Osaka Organic Chemical Industry Ltd.).

[0033] The polyfunctional (meth)acrylate (A) may have a substituent such as a vinyl group, a carboxyl group, or a hydroxyl group.

[0034] Among the components (A), polyfunctional (meth)acrylates containing a polyisoprene skeleton are preferred because they have excellent adhesive properties and heat resistance.

[0035] The content of the (A) polyfunctional (meth)acrylate is preferably in the range of 5 to 50 parts by mass, more preferably 5 to 40 parts by mass, and particularly preferably 10 to 35 parts by mass, relative to 100 parts by mass of the total of (A), (B), the (E) aliphatic monofunctional (meth)acrylate added as desired (described later), and other (meth)acrylates. By adjusting the content to the range of 5 to 50 parts by mass, the balance between flexibility and adhesiveness can be adjusted to an appropriate range.

[0036] [Component (B)] The anaerobic adhesive of the present disclosure contains (B) a polyfunctional (meth)acrylate containing an alicyclic skeleton. The polyfunctional (meth)acrylate containing an alicyclic skeleton is a polyfunctional (meth)acrylate that has an alicyclic structure in its skeleton and has two or more (meth)acryloyl groups per molecule. By containing (B) a polyfunctional (meth)acrylate containing an alicyclic skeleton, heat resistance is improved. One type of (B) polyfunctional (meth)acrylate containing an alicyclic skeleton may be used alone, or two or more types may be used in combination.

[0037] The alicyclic skeleton is not particularly limited and may be a monocyclic structure or a polycyclic structure such as a bicyclic structure or a tricyclic structure. More specific examples include a cycloalkane ring such as cyclohexane, an isobornyl ring, a tricyclodecane ring, and an adamantyl ring. Among these, a tricyclodecane ring is preferred because it has better heat resistance and is also excellent in compatibility with the (A) polyfunctional (meth)acrylate.

[0038] The number of (meth)acryloyl groups in the (B) polyfunctional (meth)acrylate containing an alicyclic skeleton may be two or more, preferably 2 to 10, more preferably 2 to 6, even more preferably 2 to 4, particularly preferably 2 or 3, and most preferably 2. More specific examples of the (B) polyfunctional (meth)acrylate include cyclohexanedimethanol di(meth)acrylate, ethoxylated cyclohexanemethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, adamantyldiol di(meth)acrylate, and adamantanetriol di(meth)acrylate. Among these, tricyclodecane dimethanol di(meth)acrylate is more preferred due to its excellent heat resistance.

[0039] The content of the (B) polyfunctional (meth)acrylate is preferably in the range of 30 to 70 parts by mass, more preferably 35 to 55 parts by mass, and particularly preferably 35 to 50 parts by mass, per 100 parts by mass of the total of (A), (B), the (E) aliphatic monofunctional (meth)acrylate added as desired (described later), and other (meth)acrylates. By setting the content in the range of 30 to 70 parts by mass, both heat resistance and adhesive strength can be achieved.

[0040] [Component (C)] The anaerobic adhesive of the present disclosure contains a peroxide (C) as a polymerization initiator. The peroxide (C) may be used alone or in combination of two or more types.

[0041] The peroxide (C) may be any peroxide that can be used as a polymerization initiator for anaerobic adhesives. Examples include hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide, p-menthane hydroperoxide, methyl ethyl ketone peroxide, cyclohexane peroxide, dicumyl peroxide, and diisopropylbenzene hydroperoxide, as well as organic peroxides such as ketone peroxides, diallyl peroxides, and peroxyesters. Among these, hydroperoxides are preferred from the viewpoint of the curability and storage stability of the anaerobic adhesive.

[0042] The content of (C) peroxide is preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the total of (A), (B), the optionally added (E) aliphatic monofunctional (meth)acrylate described below, and the other (meth)acrylates, from the viewpoint of curability. Furthermore, from the viewpoint of further improving the storage stability of the anaerobic adhesive composition, the content is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. From the above viewpoints, the content is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass.

[0043] [Component (D)] The anaerobic adhesive of the present disclosure contains (D) an anaerobic curing catalyst. Examples of the anaerobic curing catalyst include aromatic sulfimide compounds, amine compounds, azole compounds, mercaptan compounds, hydrazine compounds, and salts thereof. One type of (D) anaerobic curing catalyst may be used alone, or two or more types may be used in combination.

[0044] Examples of the aromatic sulfimide compounds include o-sulfobenzimid.

[0045] Examples of the amine compounds include heterocyclic amine compounds and aromatic amine compounds. Examples of the heterocyclic amine compounds include heterocyclic secondary amine compounds such as 1,2,3,4-tetrahydroquinoline and 1,2,3,4-tetrahydroquinaldine, and heterocyclic tertiary amine compounds such as quinoline, methylquinoline, quinaldine, quinoxaline, tetrahydroquinoline, tetrahydroquinaldine, and quinoxalinephenazine. Examples of the aromatic amine compounds include aromatic tertiary amine compounds such as N,N-dimethylanisidine, N,N-dimethylnaphthylamine, aniline-based aromatic tertiary amine compounds, and toluidine-based aromatic tertiary amine compounds. Examples of the aniline-based aromatic tertiary amine compounds include N,N-dimethylaniline and N,N-diethylaniline. Examples of the toluidine-based aromatic tertiary amine compounds include N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine, and N,N-dimethyl-o-toluidine.

[0046] Examples of the azole compound include 1,2,4-triazole, oxazole, oxadiazole, thiadiazole, benzotriazole, hydroxybenzotriazole, benzoxazole, 1,2,3-benzothiadiazole, and 3-mercaptobenzotriazole.

[0047] Examples of the mercaptan compound include linear mercaptans such as n-dodecyl mercaptan, ethyl mercaptan, and butyl mercaptan.

[0048] Examples of the hydrazine compound include 1-acetyl-2-phenylhydrazine, 1-acetyl-2(p-tolyl)hydrazine, 1-benzoyl-2-phenylhydrazine, 1-(1',1',1'-trifluoro)acetyl-2-phenylhydrazine, 1,5-diphenyl-carbohydrazine, 1-formyl-2-phenylhydrazine, 1-acetyl-2-(p-bromophenyl)hydrazine, 1-acetyl-2-(p-nitrophenyl)hydrazine, and 1-acetyl-2-(p-nitrophenyl)hydrazine. p-nitrophenylhydrazine, 1-acetyl-2-(2'-phenylethylhydrazine), p-nitrophenylhydrazine, and p-trisulfonylhydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanediohydrazide, isophthalic acid dihydrazide, propionic acid hydrazide, salicylic acid hydrazide, ethyl carbazate, 4-(methylsulfonyl)phenylhydrazine, N-aminorhodanine, and the like.

[0049] Examples of the salts of the hydrazine compounds include 4-methylsulfonylphenylhydrazine hydrochloride, hydrazine monohydrochloride, and p-tolylhydrazine hydrochloride.

[0050] Among these, the anaerobic curing catalyst (D) is preferably at least one selected from the group consisting of aromatic amine compounds and hydrazine compounds, because aromatic amine compounds have good compatibility and hydrazine compounds have good solubility. The aromatic amine compound is more preferably an aromatic tertiary amine compound.

[0051] Furthermore, it is more preferable to contain a hydrazine compound as the anaerobic curing catalyst (D) because it provides excellent adhesion and heat resistance. When a catalyst other than a hydrazine compound is used, it is preferable to use it in combination with o-sulfobenzimide.

[0052] The content of (D) anaerobic curing catalyst is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and particularly preferably 0.03 to 3 parts by mass, per 100 parts by mass of the total of (A), (B), the optionally added (E) aliphatic monofunctional (meth)acrylate, and other (meth)acrylates, as described below. Within the range of 0.001 to 10 parts by mass, the curing rate can be improved while maintaining high adhesion to metal.

[0053] [Component (E)] The anaerobic adhesive of the present disclosure preferably contains (E) an aliphatic monofunctional (meth)acrylate. By containing (E) an aliphatic monofunctional (meth)acrylate, the adhesive strength to adherends such as electrical steel sheets and SPCC can be improved. One type of (E) aliphatic monofunctional (meth)acrylate may be used alone, or two or more types may be used in combination.

[0054] As the (E) aliphatic monofunctional (meth)acrylate, any aliphatic monofunctional (meth)acrylate that is blended as a curing component of the adhesive may be used, and among them, a monofunctional (meth)acrylate containing an alicyclic skeleton is preferred from the viewpoint of heat resistance. Examples of the alicyclic skeleton include those similar to those described above. Examples of aliphatic monofunctional (meth)acrylates containing an alicyclic skeleton include isobornyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, hydrogenated bisphenol A epoxy mono(meth)acrylate, hydrogenated bisphenol F epoxy mono(meth)acrylate, hydrogenated biphenyl epoxy mono(meth)acrylate, and EO (ethylene oxide)- or PO (propylene oxide)-modified versions of these hydrogenated epoxy mono(meth)acrylates. Among these, isobornyl (meth)acrylate is preferred because it can reduce viscosity and exhibit a stronger anchoring effect on the adherend, improving adhesion.

[0055] By adding (E) an aliphatic monofunctional (meth)acrylate to the anaerobic adhesive of the present disclosure, the viscosity of the anaerobic adhesive can be reduced, and therefore the viscosity of the (E) aliphatic monofunctional (meth)acrylate at 25° C. is preferably 10 mPa·s or less, more preferably 8 mPa·s or less. Furthermore, from the viewpoint of compatibility with the (A) polyfunctional (meth)acrylate, the solubility parameter (SP value) of the (E) aliphatic monofunctional (meth)acrylate is preferably 8.5 to 9.4, and since it is possible to easily reduce the viscosity of the anaerobic adhesive of the present disclosure, the production efficiency of adhesive laminates can be improved by employing a coating method using, for example, a jet dispenser. Examples of aliphatic monofunctional (meth)acrylates having a viscosity at 25°C and an SP value within the above ranges include lauryl methacrylate (SP value 9.2), isobornyl acrylate (SP value 8.7), isobornyl methacrylate (SP value 8.7), and t-butylcyclohexyl acrylate (SP value 9.0).

[0056] The SP value can be calculated according to the method proposed by Fedors et al. (see Polymer Engineering and Science, 14, 147-154 (1974)). That is, it can be calculated based on the following formula: SP value δ=(ΣΔe / ΣΔv) １／２ (In the above formula, Δe is the vaporization energy of each atom or atomic group at 25°C, and Δv is the molar volume of each atom or atomic group at the same temperature.)

[0057] The content of the aliphatic monofunctional (meth)acrylate (E) is preferably in the range of 10 to 50 parts by mass, and more preferably in the range of 15 to 45 parts by mass, per 100 parts by mass of the total of (A), (B), (E), and other (meth)acrylates.

[0058] The anaerobic adhesive of the present disclosure may also contain various additives commonly used in adhesives, provided that the effects of the present disclosure are not impaired. Examples of additives include colorants, flame retardants, stabilizers, radical absorbers, chelating agents, antioxidants, fillers, leveling agents, anti-sagging agents, coupling agents, antifoaming agents, surfactants, drying oils, adhesion promoters, flow control agents, plasticizers, and elastomers.

[0059] The method for producing the anaerobic adhesive of the present disclosure is not particularly limited, and the adhesive can be produced by a known method. For example, the adhesive can be produced by blending predetermined amounts of each component and mixing them using a mixing means such as a mixer at a temperature of preferably 10°C to 100°C for preferably 0.1 to 5 hours.

[0060] The method for applying the anaerobic adhesive composition of the present disclosure is not particularly limited, and known methods can be used, such as dispensing, roller application, inkjet application, spraying, and dipping.

[0061] The viscosity of the anaerobic adhesive of the present disclosure may be adjusted appropriately depending on the application method described above, with the viscosity at 25°C preferably being 10,000 mPa·s or less, more preferably 10 mPa·s to 8,000 mPa·s, even more preferably 15 mPa·s to 6,000 mPa·s, and particularly preferably 30 mPa·s to 5,000 mPa·s. Furthermore, a low viscosity allows the use of, for example, a jet dispenser that uses the above-mentioned dispensing method as the application principle, so the viscosity at 25°C is preferably 1,000 mPa·s or less, more preferably 600 mPa·s or less, and even more preferably 300 mPa·s or less. From the above perspectives, the viscosity is preferably 10 mPa·s to 1,000 mPa·s, more preferably 15 mPa·s to 600 mPa·s, and even more preferably 30 mPa·s to 300 mPa·s. The method for measuring the viscosity of the anaerobic adhesive will be described later.

[0062] The uses of the anaerobic adhesive of the present disclosure are not particularly limited, but because it has excellent adhesive properties between electromagnetic steel sheets, it can be suitably used for laminating electromagnetic steel sheets.

[0063] The anaerobic adhesive of the present disclosure may be used for bonding not only electrical steel sheets but also metals. In particular, the adhesive can be suitably used for bonding between metals such as aluminum and stainless steel that have an oxide film similar to electrical steel sheets. The adhesive may also be used for bonding between metals that do not have an oxide film, such as SPCC, or between a metal that has an oxide film and a metal that does not have an oxide film.

[0064] (Adhesive Laminate) The adhesive laminate of the present disclosure is an adhesive laminate formed by bonding and laminating two or more electrical steel sheets with the anaerobic adhesive of the present disclosure.

[0065] The electromagnetic steel sheet is not particularly limited, and may be either a directional electromagnetic steel sheet or a non-directional electromagnetic steel sheet. When the adhesive laminate of the present disclosure is used for a motor core, rotor, stator, etc., as described below, the electromagnetic steel sheet is preferably a non-directional electromagnetic steel sheet. Furthermore, the lamination method is not particularly limited, and adhesive lamination may be performed using only the anaerobic adhesive of the present disclosure, or adhesive lamination may be combined with other lamination methods. For example, when laminating by the caulking method, the anaerobic adhesive of the present disclosure may be applied to the electromagnetic steel sheets to bond them together.

[0066] The thickness of the electromagnetic steel sheet is not particularly limited, but is preferably in the range of 50 μm to 1 mm, for example. The upper limit of the thickness is more preferably 0.5 mm or less, and even more preferably 0.3 mm or less. Although iron loss decreases when the thickness of the electromagnetic steel sheet is reduced, if the thickness is too thin, shape stability decreases and the manufacturing cost of the electromagnetic steel sheet increases, so it is preferable to set the thickness to 50 μm or more. Increasing the thickness of the electromagnetic steel sheet makes it possible to integrate the electromagnetic steel sheets by caulking or welding, so it is preferable that the thickness be 1 mm or less. From the above-mentioned viewpoints, it is more preferable that the thickness is 50 μm to 0.5 mm, and even more preferably 50 μm to 0.3 mm.

[0067] The thickness of the adhesive layer is preferably 0.1 μm to 1,000 μm, and more preferably 0.5 μm to 500 μm.

[0068] The shape of the electrical steel sheet, particularly the shape in the plane direction, is not particularly limited, and any appropriate shape can be selected as desired.

[0069] The number of electromagnetic steel sheets used in the adhesive laminate of the present disclosure is not particularly limited and can be selected appropriately depending on the usage of the motor or the like.

[0070] The adhesive laminate of the present disclosure is not particularly limited in its application, but can be suitably used for motor components, particularly stators, rotors, and motor cores. When the anaerobic adhesive of the present disclosure is used in a motor core, the cured product of the anaerobic adhesive of the present disclosure electrically insulates each of the multiple electrical steel sheets that make up the motor core. Therefore, a motor core using the adhesive laminate of the present disclosure has low current loss, high performance, and high reliability, and distributes stress across the surface, preventing stress concentration and strain concentration. As a result, the adhesive laminate of the present disclosure is suitably used in motor cores and the like.

[0071] (Motor) The motor of the present disclosure includes the adhesive laminate of the present disclosure.

[0072] Motors using the adhesive laminate of the present disclosure as a motor core are suitable for use in mobile phone vibration, camera focus adjustment, hard disk drive, automobile drive, etc. The anaerobic adhesive of the present disclosure has excellent heat resistance and is therefore particularly suitable for use in automobile drive.

[0073] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples. In the following, all percentages are by mass unless otherwise specified.

[0074] (Production of anaerobic adhesive) The components (A), (B), and (E) listed in Table 1 or Table 2 were weighed and stirred for 10 minutes using a mixer. Then, the component (D) listed in Table 1 or Table 2 was added and stirred for 1 hour. Furthermore, the component (C) listed in Table 1 or Table 2 was added and stirred for 10 minutes to obtain an anaerobic adhesive. The stirring was carried out while the mixture was heated to 40°C.

[0075] (Measurement of Adhesion Strength) 1. Method of Preparing Test Pieces 10 mg of the anaerobic adhesive obtained above was applied to a 25 mm wide x 100 mm long x 250 μm thick electrical steel sheet (manufactured by Nippon Steel Corporation, product name: Hi-Excore 25HX) in a 25 mm wide x 12.5 mm long area of ​​a first test piece. On the other hand, 10 mg of a primer liquid (copper soap solution) was applied to a 25 mm wide x 12.5 mm long area of ​​a second test piece (manufactured by Nippon Steel Corporation, product name: Hi-Excore 25HX) in a 25 mm wide x 100 mm long x 250 μm thick electrical steel sheet. The copper soap solution was a mixture of ethanol and copper soap.

[0076] The two test pieces were then overlapped with each other so that the portion of the first test piece coated with the anaerobic adhesive and the portion of the second test piece coated with the primer liquid overlapped, and the two test pieces were fixed together with a pinch cock. This laminate was left to stand for 24 hours, and the pinch cock was removed to obtain a test piece laminated with an electromagnetic steel sheet. For the examples, a test piece laminated with an SPCC-SD steel sheet was also prepared under the same conditions, except that the electromagnetic steel sheet was changed to a 100 mm x 25 mm x 1.6 mm SPCC-SD steel sheet.

[0077] 2. Method for measuring adhesive strength Using an Instron universal testing machine #5982, test pieces laminated with electrical steel sheets obtained by the manufacturing method in 1 above were fixed to grippers, and pulled at a pulling rate of 5 mm / min so that a load was applied horizontally to the adhesive surface in an environment of 25°C or 200°C, and the maximum load until the test piece broke was measured, and this was taken as the adhesive strength of each test piece. In the examples, adhesive strength was also measured in the same way for test pieces laminated with SPCC-SD steel sheets.

[0078] (Viscosity Measurement) The viscosity of each anaerobic adhesive was measured using an E-type viscometer (VISCOMETER TV-35, manufactured by Toki Sangyo Co., Ltd.) at 25° C., 100 rpm, after 2 minutes, with a cone plate having a diameter of 28 mm and an angle of 3°.

[0079]

[0080] A1: Kuraray Co., Ltd., Kuraprene UC-102M (polyisoprene backbone, 2 functional groups) A2: Kuraray Co., Ltd., Kuraprene UC-203M (polyisoprene backbone, 3 functional groups) A3: Nippon Soda Co., Ltd., NISSO-PB TE-2000 (polybutadiene backbone, 2 functional groups) A4: Osaka Organic Chemical Industry Co., Ltd., BAC-45 (polybutadiene backbone, 2 functional groups) A5: Nippon Soda Co., Ltd., NISSO-PB TEAI-1000 (hydrogenated polybutadiene backbone, 2 functional groups) A'1: Daicel-Allnex Co., Ltd., EBECRYL 230 (aliphatic urethane diacrylate, 2 functional groups) A'2: Daicel-Allnex Co., Ltd., EBECRYL 11 (PEG600 diacrylate, 2 functional groups) B1: NK Ester DCP (tricyclodecane dimethanol dimethacrylate, functionality 2) manufactured by Shin-Nakamura Chemical Co., Ltd. B2: NK Ester A-DCP (tricyclodecane dimethanol diacrylate, functionality 2) manufactured by Shin-Nakamura Chemical Co., Ltd. C1: Percumyl H-80 (cumene hydroperoxide) manufactured by NOF Corporation D1: 1-acetyl-2-phenylhydrazine manufactured by Tokyo Chemical Industry Co., Ltd. D2: N,N-diethyl-p-toluidine manufactured by Tokyo Chemical Industry Co., Ltd. D3: o-sulfobenzimid e manufactured by Tokyo Chemical Industry Co., Ltd. E1: Acrylate IBX (isobornyl methacrylate, functionality 1, SP value 8.7) manufactured by Mitsubishi Chemical Corporation E2: TBCHA (t-butylcyclohexyl acrylate, functionality 1, SP value 9.0) manufactured by KJ Chemicals

[0081]

[0082] The results shown in Tables 1 and 2 demonstrate that the anaerobic adhesive of the present invention has excellent adhesion and heat resistance. In particular, comparison with Comparative Example 1, which does not contain component (A), and Comparative Examples 4 and 5, which do not contain component (B), demonstrates that the anaerobic adhesive of the present invention has significantly superior adhesion and heat resistance. Furthermore, as shown in Comparative Examples 2 and 3, it is clear that even when aliphatic urethane diacrylate or polyethylene glycol diacrylate is blended as a flexible (meth)acrylate, it is not possible to achieve both excellent adhesion and heat resistance. Comparative Example 6 demonstrates that the absence of component (C) results in poor adhesion and heat resistance.

Claims

1. (A) a polyfunctional (meth)acrylate containing at least one skeleton selected from the group consisting of polyisoprene and polybutadiene; (B) a polyfunctional (meth)acrylate containing an alicyclic skeleton, (C) a peroxide, and (D) an anaerobic curing catalyst; An anaerobic adhesive comprising:

2. 2. The anaerobic adhesive according to claim 1, wherein the anaerobic curing catalyst (D) is at least one selected from the group consisting of aromatic amine compounds and hydrazine compounds.

3. The anaerobic adhesive according to claim 1, further comprising (E) an aliphatic monofunctional (meth)acrylate.

4. 2. The anaerobic adhesive according to claim 1, wherein the (B) polyfunctional (meth)acrylate containing an alicyclic skeleton is a polyfunctional (meth)acrylate containing a tricyclodecane skeleton.

5. 2. The anaerobic adhesive according to claim 1, which is for laminating electromagnetic steel sheets.

6. 2. The anaerobic adhesive according to claim 1, which is used for bonding between metals.

7. The anaerobic adhesive according to claim 6, wherein the metal has an oxide coating.

8. A cured product obtained by curing the anaerobic adhesive according to any one of claims 1 to 7.

9. An adhesive laminate in which electromagnetic steel sheets are laminated using the anaerobic adhesive according to any one of claims 1 to 7.

10. A motor using the adhesive laminate according to claim 9.