Steel sheet laminate production method, steel sheet laminate, and adhesive composition

Abstract

The present invention addresses: a first problem of providing a steel sheet laminate production method with which it is possible to produce a steel sheet laminate having excellent adhesive strength, in which the curing speed of an adhesive is sufficiently quick and the time necessary for completing adhesion and forming the steel sheet laminate is short, and which provides good workability; and a second problem of producing a steel sheet laminate having excellent adhesive strength. As a solution to the problems, provided is a steel sheet laminate production method that involves adhering steel sheets having applied thereto a primer containing a copper compound, by using a radically polymerizable adhesive composition containing (A) a radically polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radically polymerizable group. In the method, the amount of the phosphate ester compound (C) having a radically polymerizable group is not less than 0.055 parts by mass but less than 1 part by mass with respect to 100 parts by mass of the radically polymerizable compound (A).

Description

Method for manufacturing steel sheet laminate, steel sheet laminate and adhesive composition

[0001] The present invention relates to a method for producing a steel sheet laminate, a steel sheet laminate, and an adhesive composition.

[0002] Steel sheet laminates, manufactured by laminating steel sheets, particularly electromagnetic steel sheets, are used in applications such as motor rotors and stators installed in various devices. Steel sheet laminates are typically laminated by caulking or welding. However, as laminated electromagnetic steel sheets become thinner, it has become necessary to address iron loss caused by stress concentration, strain concentration, and electrical short circuits between layers due to mechanical fastening. For this reason, a technology using an insulating adhesive to manufacture steel sheet laminates has attracted attention as a method for reducing iron loss by dispersing stress. Curable resins such as epoxy resin adhesives and curable acrylic adhesives are commonly used as adhesives. Among these, curable acrylic adhesives are often used when room temperature curing is desired. Patent Document 1 describes the production of a steel sheet laminate using an anaerobic adhesive (a type of curable acrylic adhesive) and steel sheets whose surfaces are coated with press processing oil containing copper soap as a curing accelerator. Patent Document 2 describes a method of applying a pretreatment agent for accelerating the curing of an anaerobic adhesive containing a chelate compound of copper, vanadium, chromium, manganese, iron, titanium, nickel, or cobalt as an active ingredient to a metal bolt / nut, followed by applying an anaerobic adhesive containing a (meth)acrylate compound to secure the bolt / nut. Patent Document 3 describes a method of applying a curing accelerator for a (meth)acrylic curable composition containing a copper and / or vanadium chelate compound to a metal bolt / nut, followed by applying an anaerobic adhesive containing a (meth)acrylate compound to secure the bolt / nut. Patent Document 4 describes a method of applying an anaerobic adhesive composition containing an anaerobically polymerizable acrylic acid ester monomer, an organic peroxide, and a phosphoric acid compound having a (meth)acryloyl group to the inner wall and / or shaft of a ring, and then inserting the shaft into the ring and fitting to secure the shaft. Patent Document 5 describes the use of a polymerizable adhesive composition containing a polymerizable olefinically unsaturated monomer compound, a phosphoric acid compound having at least one olefinically unsaturated group, and an organic peroxide for bonding steel to steel and aluminum to aluminum.Patent Document 6 describes a composition comprising: component (A): a radical polymerizable compound; component (B): a radical polymerization initiator; and component (C): a compound represented by the following formula (1) or (2): -O-P(O)(OH)-O- (1) -O-P(O)(OH). ２ A radical polymerizable adhesive composition for bonding steel sheet laminates is disclosed, which contains a phosphoric acid ester compound having a group represented by the following formula (2):

[0003] Japanese Patent Application Laid-Open No. 2006-334648 Japanese Patent Publication No. 49-021093 Japanese Patent Application Laid-Open No. 60-179407 Japanese Patent Application Laid-Open No. 51-132234 Japanese Patent Application Laid-Open No. 54-141826 International Publication No. 2019 / 123885

[0004] The adhesive compositions described in Patent Documents 1 to 6 can produce steel sheet laminates with excellent adhesive strength, but they have an insufficient curing rate, a long time required for completion of bonding and construction of a steel sheet laminate, and poor workability. The problem to be solved by the present invention is to provide a method for producing a steel sheet laminate with excellent adhesive strength, which allows production of a steel sheet laminate with excellent adhesive strength, the curing rate of the adhesive is sufficiently fast, the time required for completion of bonding and construction of a steel sheet laminate is short, and workability is good. Another problem to be solved by the present invention is to provide an adhesive composition for steel sheet laminates with excellent adhesive strength, which allows production of a steel sheet laminate with excellent adhesive strength, the curing rate of the adhesive is sufficiently fast, the time required for completion of bonding and construction of a steel sheet laminate is short, and workability is good.

[0005] The present inventors conducted extensive research to solve the above-mentioned problems, and as a result, found that the above-mentioned problems can be solved by a method for producing a steel sheet laminate using a specific adhesive composition, and the steel sheet laminate and specific adhesive composition obtained thereby, thereby completing the present invention. Specifically, the present invention is as follows. [Item 1] A method for producing a steel sheet laminate in which steel sheets coated with a primer containing a copper compound are bonded using a radically polymerizable adhesive composition containing (A) a radically polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radically polymerizable group, wherein the amount of (C) the phosphate ester compound having a radically polymerizable group is 0.055 parts by mass or more and less than 1 part by mass per 100 parts by mass of the (A) radically polymerizable compound. [Item 2] A steel sheet laminate produced by the method described in Item 1. [Item 3] An adhesive composition for a steel sheet laminate, which bonds steel sheets coated with a primer containing a copper compound, the adhesive composition containing (A) a radical polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radical polymerizable group, in which the amount of the phosphate ester compound having the radical polymerizable group (C) is 0.055 parts by mass or more and less than 1 part by mass per 100 parts by mass of the (A) radical polymerizable compound.

[0006] The present invention provides a method for producing a steel sheet laminate that can produce a steel sheet laminate with excellent adhesive strength, has a sufficiently fast curing rate of the adhesive, requires a short time for bonding to be completed and the steel sheet laminate to be constructed, and has good workability.The present invention also provides an adhesive composition for a steel sheet laminate that can produce a steel sheet laminate with excellent adhesive strength, has a sufficiently fast curing rate of the adhesive, requires a short time for bonding to be completed and the steel sheet laminate to be constructed, and has good workability.The method for producing a steel sheet laminate and the adhesive composition for a steel sheet laminate according to the present invention can simplify the manufacturing process of the steel sheet laminate, reduce iron loss in the steel sheet laminate, and contribute to improving the performance and reliability of motor rotors and stators, and are therefore extremely effective and industrially useful because they can be applied in a wide range of fields. The adhesive composition for steel sheet laminates of the present invention exhibits excellent adhesive strength to steel sheets whose surfaces have been treated with punching oil, in particular to electrical steel sheets and cold-rolled steel sheets (SPCC-SD), and is capable of providing strong adhesion without removing the punching oil applied to the steel sheets in the process of producing the steel sheet laminate, making it extremely useful from an industrial perspective.

[0007] 1 is a schematic diagram of a manufacturing apparatus for a steel sheet stack according to an embodiment of the present invention.

[0008] The method for producing a steel sheet laminate, the steel sheet laminate, and the adhesive composition of the present invention will be described in detail below. In this specification, "(meth)acrylic" means "acrylic" and "methacrylic", "(meth)acrylate" means "acrylate" and "methacrylate", and "(meth)acryloyl" means "acryloyl" and "methacryloyl", respectively.

[0009] [Method for Producing a Steel Sheet Laminate] The method for producing a steel sheet laminate of the present invention involves bonding steel sheets coated with a primer containing a copper compound using a radical-polymerizable adhesive composition containing (A) a radical-polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radical-polymerizable group. The radical-polymerizable adhesive composition contains (C) a phosphate ester compound having a radical-polymerizable group in an amount of 0.055 parts by mass or more and less than 1 part by mass per 100 parts by mass of the (A) radical-polymerizable compound.

[0010] <Radical Polymerizable Adhesive Composition> ((A) Radical Polymerizable Compound) The (A) radical polymerizable compound contained in the radical polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention is at least one compound selected from the group consisting of radical polymerizable monomers, radical polymerizable oligomers, and radical polymerizable polymers having a radical polymerizable functional group, in particular, a radically polymerizable ethylenically unsaturated group. The (A) radical polymerizable compound is a radical polymerizable compound other than the (C) phosphate ester compound having a radical polymerizable group described below. Examples of the radical polymerizable functional group include a (meth)acryloyl group, a vinyl group, an allyl group, and a (meth)acrylamide group. Of these, a (meth)acryloyl group is preferred.

[0011] From the viewpoint of adhesive strength to steel sheets, particularly electromagnetic steel sheets, having a punching oil component applied to the surface thereof, it is preferable to use one or more radically polymerizable oligomers and / or radically polymerizable polymers as the (A) radically polymerizable compound. Furthermore, from the viewpoint of exhibiting superior adhesive strength to steel sheets such as cold-rolled steel sheets and electromagnetic steel sheets, adjusting the viscosity of the adhesive composition to be easy to handle, and preventing the adhesive from squeezing out when the steel sheets are laminated, it is preferable to use one or more radically polymerizable oligomers and / or radically polymerizable polymers in combination with one or more radically polymerizable monomers.

[0012] {Radical Polymerizable Oligomer and / or Radical Polymer} Examples of the radical polymerizable oligomer and / or radical polymer include one or more selected from the group consisting of urethane (meth)acrylate, epoxy (meth)acrylate, bisphenol alkylene oxide adduct (meth)acrylate, ether (meth)acrylate, ester (meth)acrylate, isoprene-based (meth)acrylate, hydrogenated isoprene-based (meth)acrylate, (meth)acrylic group-containing acrylic polymer, (meth)acrylic group-containing polyisobutylene, etc. Among these, it is preferable to use one or more selected from the group consisting of urethane (meth)acrylate, epoxy (meth)acrylate, bisphenol alkylene oxide adduct (meth)acrylate, and ether (meth)acrylate because of their excellent adhesive strength to cold-rolled steel sheets and / or electromagnetic steel sheets and the high glass transition temperature of the cured product.

[0013] Urethane (meth)acrylates can be obtained by reacting at least a polyol component, a polyisocyanate component, and a compound having a (meth)acrylate group. The polyol component can include, for example, one or more polymer polyols selected from the group consisting of (hydrogenated) butadiene polyols, polycarbonate polyols, polyether polyols, polyester polyols, polyacrylate polyols (acrylic polyols), polyurethane polyols, etc. The polyisocyanate component can include, for example, one or more selected from the group consisting of aliphatic polyisocyanates (e.g., hexamethylene diisocyanate), alicyclic polyisocyanates (e.g., dicyclohexylmethane diisocyanate, isobornyl diisocyanate), aromatic polyisocyanates (e.g., toluene diisocyanate, diphenylmethane diisocyanate), and araliphatic polyisocyanates (e.g., xylylene diisocyanate). As the compound having a (meth)acrylate group, for example, one or more compounds selected from the group consisting of (meth)acrylate group-containing compounds having a group reactive with an isocyanate group (hydroxyalkyl (meth)acrylate, acrylic acid, etc.) and isocyanate group-containing (meth)acrylate group-containing compounds can be used.

[0014] Examples of the urethane (meth)acrylate include one or more selected from the group consisting of urethane (meth)acrylates having a (hydrogenated) polybutadiene skeleton, urethane (meth)acrylates having a polycarbonate skeleton, urethane (meth)acrylates having a polyether skeleton, urethane (meth)acrylates having a polyester skeleton, urethane (meth)acrylates having a polyacrylate skeleton, urethane (meth)acrylates having a polyurethane skeleton, and urethane (meth)acrylates having a castor oil skeleton.

[0015] Epoxy (meth)acrylates can be obtained by reacting an epoxy resin with a (meth)acrylate compound having a functional group reactive with an epoxy group. Examples of epoxy resins include at least one selected from the group consisting of bisphenol-type epoxy resins (such as bisphenol A-type epoxy resins and bisphenol F-type epoxy resins), phenol novolac-type epoxy resins, and epoxy resins such as terminal glycidyl ethers of alkylene oxide adducts of bisphenol-type epoxy resins. Examples of (meth)acrylate compounds having a functional group reactive with an epoxy group include at least one selected from the group consisting of (meth)acrylate compounds having a carboxyl group such as (meth)acrylic acid, and (meth)acrylate compounds having a hydroxyl group such as hydroxyethyl (meth)acrylate. Commercially available epoxy (meth)acrylates can be used. Examples thereof include one or more selected from the group consisting of DICLITE (registered trademark) UE-8071-60BH, UE-8740, UE-8410 (all manufactured by DIC Corporation), Kayard R-115F (manufactured by Nippon Kayaku Co., Ltd.), HITAROID 7851 (manufactured by Showa Denko KK), Epoxy Ester 3000MK, 3000A (manufactured by Kyoeisha Chemical Co., Ltd.), Viscoat V#540 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), EBECRYL 600, EBECRYL 3700 (manufactured by Daicel Allnex Co., Ltd.), and the like.

[0016] Examples of the bisphenol alkylene oxide adduct (meth)acrylate include those represented by the following formula (A): (In formula (A), R １１ is a hydrogen atom or a methyl group. １２ is a hydrogen atom or a methyl group. １ is an alkylene group having 1 to 6 carbon atoms, and when there are a plurality of groups, they may be different from each other. ２ represents an alkylene group having 1 to 6 carbon atoms, and when there are a plurality of groups, they may be different from each other. X represents a direct bond, —CH ２ -, -C(CH ３ ) ２ -, -CH(CH ３ )-, -O-, -S-, -SO ２ -, -CO-, -CF ２-, -C(CF ３ ) ２ -, -C(Ph) ２ -, -CH(Ph)- (Ph is a phenyl group). m is an integer of 0 or 1 or more. n is an integer of 0 or 1 or more.) Examples include one or more compounds represented by the formula (A). For example, one or more compounds selected from the group consisting of (poly)ethoxy-modified bisphenol A di(meth)acrylate, (poly)propoxy-modified bisphenol A di(meth)acrylate, etc. are included. Among these, (poly)ethoxy-modified bisphenol A di(meth)acrylate is preferred, and in the compound represented by formula (A) above, R １１ is a hydrogen atom or a methyl group, and R １２ is a hydrogen atom or a methyl group, and A １ and A ２ is an alkylene group having 2 carbon atoms, and X is —C(CH ３ ) ２ Particularly preferred are compounds in which m+n (ie, ethoxy equivalents) is 1 to 40 (preferably 2 to 10).

[0017] {Radical Polymerizable Monomer} The radical polymerizable monomer is a compound having one or more radical polymerizable groups in the molecule, and is not an oligomer or polymer, and is not particularly limited as long as it is a radical polymerizable compound other than the (C) phosphate ester compound having a radical polymerizable group. For example, one or more selected from the group consisting of monofunctional monomers, polyfunctional monomers, etc. Among these, it is preferable to include a monofunctional monomer having a functional group such as a hydroxyl group, a carboxyl group, an amino group, or a glycidyl group, since this allows for the formation of a radical polymerizable adhesive composition for steel sheet laminates that has even better adhesion to steel sheets such as cold-rolled steel sheets and electromagnetic steel sheets and a cured product with a high glass transition temperature.

[0018] Examples of monofunctional monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and benzyl (meth)acrylate. , phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxytetraethylene glycol (meth)acrylate, nonylphenoxyethyl (meth)acrylate, nonylphenoxytetraethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, butoxytriethylene glycol (

[0039] Examples of the hydroxyethyl (meth)acrylate include one or more selected from the group consisting of methyl methyl acrylate, 2-ethylhexyl polyethylene glycol (meth)acrylate, nonylphenyl polypropylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, glycerol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, modified butyl (meth)acrylate, epichlorohydrin-modified phenoxy (meth)acrylate, ethylene oxide-modified phthalic acid (meth)acrylate, ethylene oxide-modified succinic acid (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and morpholino (meth)acrylate.Among these, from the viewpoint of achieving even better adhesion to cold-rolled steel sheets and / or electromagnetic steel sheets and faster curing properties (short set time), one or more selected from the group consisting of dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and the like are preferred.

[0019] Examples of polyfunctional monomers include 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ethylene oxide-modified neopentyl glycol di(meth)acrylate, propylene oxide-modified neopentyl glycol di(meth)acrylate, hydroxypivalic acid ester neopentyl glycol diacrylate, caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl di(meth)acrylate, ethylene oxide-modified dicyclopentenyl Di(meth)acrylate, di(meth)acryloyl isocyanurate, dimethyloltricyclodecane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, epichlorohydrin-modified trimethylolpropane tri(meth)acrylate, epichlorohydrin-modified glycerol tri(meth)acrylate

[0043] Examples of the hydroxybenzoates include one or more selected from the group consisting of alkyl-modified dipentaerythritol pentaacrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like.Among these, from the viewpoint of achieving even better adhesion to cold-rolled steel sheets and / or electromagnetic steel sheets and faster curing properties (short set time), it is preferable to use one or more selected from the group consisting of dicyclopentenyl di(meth)acrylate, ethylene oxide-modified dicyclopentenyl di(meth)acrylate, di(meth)acryloyl isocyanurate, dimethyloltricyclodecane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(acryloyloxyethyl)isocyanurate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and the like.

[0020] The amount of the radically polymerizable compound (A) blended is, for example, 90% by mass or more, preferably 95% by mass or more, and for example, 99% by mass or less, preferably 98% by mass or less, based on 100% by mass of the total amount of the radically polymerizable adhesive composition.

[0021] ((B) Organic Peroxide) The (B) organic peroxide contained in the radically polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention is intended to impart anaerobic curability and / or heat curability to the radically polymerizable adhesive composition. Examples of the (B) organic peroxide include one or more selected from the group consisting of 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 ketone peroxides, diallyl peroxides, and peroxy esters. Of these, hydroperoxides are preferably used from the viewpoint of achieving even better reactivity and storage stability of the radically polymerizable adhesive composition for bonded steel sheet laminates.

[0022] From the viewpoint of excellent anaerobic curing properties, (B) organic peroxides having a one-hour half-life temperature of 80°C or higher, preferably 100°C or higher, and 300°C or lower, preferably 200°C or lower, are preferred. The one-hour half-life temperature is a value measured by thermal decomposition under conditions where the organic peroxide concentration in benzene is 0.1 mol / L. Examples of organic peroxides having a one-hour half-life temperature in the range of 80°C or higher and 300°C or lower include hydroperoxides. Specific examples of hydroperoxides include one or more selected from the group consisting of p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide.

[0023] The amount of the (B) organic peroxide blended is, for example, 0.05 parts by mass or more, preferably 0.1 parts by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass or less, relative to 100 parts by mass of the (A) radical polymerizable compound. By blending the (B) organic peroxide in an amount of 0.05 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the (A) radical polymerizable compound, the adhesive strength of the radical polymerizable adhesive composition can be improved.

[0024] (C) Phosphate compound having a radical polymerizable group The phosphate compound having a radical polymerizable group (C) contained in the radical polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention comprises a radical polymerizable functional group and a compound represented by the following formula (1) or (2): -O-P(O)(OH)-O- ... (1) -O-P(O)(OH) ２ ...(2) By using (A) a radically polymerizable compound and (B) an organic peroxide in combination, a radically polymerizable adhesive composition for steel sheet laminates that exhibits adhesive strength to steel sheets the surfaces of which are covered with punching oil can be obtained, which is a remarkable effect.

[0025] The (C) phosphoric acid ester compound having a radical polymerizable group is not particularly limited, and examples thereof include one or more compounds selected from the group consisting of 2-hydroxymethyl(meth)acrylate acid phosphate, 2-hydroxyethyl(meth)acrylate acid phosphate, 2-hydroxypropyl(meth)acrylate acid phosphate, ethylene oxide-modified di(meth)acrylate phosphoric acid, ethylene oxide-modified tri(meth)acrylate phosphoric acid, and caprolactone-modified ethylene oxide-modified di(meth)acrylate phosphoric acid.

[0026] The (C) phosphate ester compound having a radical polymerizable group may be synthesized or may be a commercially available product, such as one or more selected from the group consisting of Light Ester P-A, P-1M, and P-2M (all manufactured by Kyoeisha Chemical Co., Ltd.), Kayamar PM-1 (manufactured by Nippon Kayaku Co., Ltd.), and JPA-514 (manufactured by Johoku Chemical Industry Co., Ltd.).

[0027] The amount of the (C) phosphate ester compound having a radical polymerizable group blended is 0.055 parts by mass or more and less than 1 part by mass relative to 100 parts by mass of the (A) radical polymerizable compound. It is preferably 0.06 parts by mass or more, more preferably 0.065 parts by mass or more, even more preferably 0.07 parts by mass or more, and preferably 0.8 parts by mass or less, more preferably 0.7 parts by mass or less. By making the amount of the (C) phosphate ester compound having a radical polymerizable group blended 0.055 parts by mass or more and less than 1 part by mass relative to 100 parts by mass of the (A) radical polymerizable compound, it is possible to increase the adhesive strength to steel plate (tensile shear adhesive strength based on JIS K 6850 (1999)) to 2.0 N / mm ２ Furthermore, the setting time (defined in the examples) can be made less than 300 seconds, preferably less than 250 seconds, and more preferably less than 180 seconds. If the amount of (C) phosphate ester compound having a radical polymerizable group is 1 part by mass or more, the tensile shear bond strength will be high and excellent adhesion will be achieved, but the setting time may be long and the curing rate may be slow. If the amount is less than 0.055 parts by mass, the setting time will be short and the curing rate will be fast, but the tensile shear bond strength will be low and adhesion may be poor.

[0028] (D) Anaerobic Curing Catalyst) The radically polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention preferably further contains (D) an anaerobic curing catalyst. Examples of (D) the anaerobic curing catalyst include one or more compounds selected from the group consisting of imide-based compounds, amine-based compounds, azole-based compounds, mercaptan-based compounds, hydrazine-based compounds, and the like. Of these, imide-based compounds are preferred from the viewpoint of improving anaerobic curability.

[0029] The imide-based compound is represented by the following formula (3) or (4): -CONHCO- (3) -CONHSO ２ - (4) or a salt thereof. Examples of the imide-based compound include one or more compounds selected from the group consisting of o-benzoic acid sulfimide (saccharin), succinic acid imide, phthalic acid imide, and salts thereof (particularly alkali metal salts such as sodium and potassium).

[0030] Examples of the amine compound include one or more compounds selected from the group consisting of heterocyclic secondary amines such as 1,2,3,4-tetrahydroquinoline and 1,2,3,4-tetrahydroquinaldine, heterocyclic tertiary amines such as quinoline, methylquinoline, quinaldine and quinoxalinephenazine, and aromatic tertiary amines such as N,N-dimethyl-anisidine and N,N-dimethylaniline.

[0031] Examples of the azole compound include one or more compounds selected from the group consisting of 1,2,4-triazole, oxazole, oxadiazole, thiadiazole, benzotriazole, hydroxybenzotriazole, benzoxazole, 1,2,3-benzothiadiazole, and 3-mercaptobenzotriazole.

[0032] The mercaptan compound may be, for example, one or more selected from the group consisting of straight-chain mercaptans such as n-dodecyl mercaptan, ethyl mercaptan, and butyl mercaptan.

[0033] 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, 1-acetyl-2-(p-methoxyphenyl)hydrazine, 1-acetyl-2-(2'-phenylethylhydrazine), p-nitrophenylhydrazine, p-trisulfonylhydrazide, 1-acetyl-2-methylhydrazine, 1-phenylsemicarbazide, 2-phenyl-t-butylcarbazate, succinic acid di(phenylhydrazide), and the like.

[0034] The amount of the (D) anaerobic curing catalyst is not particularly limited, as long as it does not impair the properties of the radical-polymerizable adhesive composition, such as ease of handling, adhesive strength, rapid curing, and storage stability. It is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and for example, 5 parts by mass or less, preferably 3 parts by mass or less, per 100 parts by mass of the (A) radical-polymerizable compound. By setting the amount of the (D) anaerobic curing catalyst to be in the range of 0.1 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the (A) radical-polymerizable compound, the radical-polymerizable adhesive composition can be made excellent in anaerobic curing properties and storage stability.

[0035] ((E) Storage Stabilizer) The radical polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention preferably further contains (E) a storage stabilizer. Examples of the storage stabilizer include one or more selected from the group consisting of polymerization inhibitors (radical scavengers, metal chelating agents), antioxidants, etc.

[0036] Examples of the polymerization inhibitor include one or more metal chelating agents selected from the group consisting of ethylenediaminetetraacetic acid, its di-sodium salt, its 4-sodium salt, oxalic acid, acetylacetone, o-aminophenol, and the like; one or more quinone compounds selected from the group consisting of hydroquinone, benzoquinone, hydroquinone monomethyl ether, β-naphthoquinone, 2-methoxy-1,4-naphthoquinone, methylhydroquinone, hydroquinone monomethyl ether, mono-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, p-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5-di-tert-butyl-p-benzoquinone, and the like; pentaerythritol tetrakis(3-(3,5-ditert-butyl)-4-benzoquinone; and one or more hindered phenol compounds selected from the group consisting of N-methyl-N-nitrosoaniline, N-nitrosodiphenylamine, N-nitrosophenylhydroxyamine aluminum salt, and the like; phosphorus compounds such as triphenyl phosphite; and one or more compounds selected from the group consisting of phenothiazine, N-isopropyl-N'-phenyl-p-phenylenediamine, diethylhydroxylamine, sulfur, t-butylcatechol, potassium triiodide, and the like.

[0037] The amount of the storage stabilizer (E) to be added is not particularly limited, and can be, for example, 7 parts by mass or less, preferably 0.001 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic polymerizable monomer (A).

[0038] (F) Other Components) The radically polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention may contain (F) other components in addition to (A) the radically polymerizable compound, (B) the organic peroxide, (C) the phosphate ester compound having a radically polymerizable group, (D) the anaerobic curing catalyst, and (E) the storage stabilizer, to the extent that the functions of the adhesive composition, such as curability and the adhesiveness of the cured product, are not impaired. Examples of (F) other components include one or more selected from the group consisting of organic fillers (elastomers, thermoplastic resins, thermosetting resins, etc.), inorganic fillers, silane coupling agents, curing rate modifiers, plasticizers, antifoaming agents, heavy metal deactivators, adhesives and / or tackifiers, antioxidants, light stabilizers, reinforcing agents, colorants, flame retardants, rust inhibitors, dispersants, thixotropic agents, precipitation inhibitors, antioxidants, light stabilizers, UV absorbers, fragrances, etc.

[0039] Examples of the organic filler include one or more selected from the group consisting of polyethylene, polypropylene, polyamide, cross-linked acrylic, cross-linked polystyrene, polyester, polyvinyl alcohol, polyvinyl butyral, polycarbonate, epoxy resin, various rubbers and elastomers (diene-based rubbers, olefin-based elastomers, urethane-based elastomers, silicone-based elastomers, etc.), and the like.

[0040] Examples of inorganic fillers include one or more selected from the group consisting of glass, silica, alumina, mica, ceramics, calcium carbonate, aluminum nitride, carbon powder, kaolin clay, dried clay minerals, dried diatomaceous earth, and the like.

[0041] The silane coupling agent is used as an adhesion promoter. Examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, octenyltrimethoxysilane, glycidoxyoctyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-isocyanatepropyltriethoxysilane, γ-ureidopropyltriethoxysilane, and p-styryltrimethoxysilane.

[0042] (Properties of the radical polymerizable adhesive composition or the cured product thereof) {Tensile shear adhesive strength} The tensile shear adhesive strength of the radical polymerizable adhesive composition of the present invention is, for example, 2.0 N / mm ２ or more, preferably 3.0 N / mm ２ The tensile shear bond strength can be measured by the method described in the Examples below.

[0043] {Setting Time} The setting time of the radically polymerizable adhesive composition of the present invention is, for example, less than 300 seconds, preferably less than 250 seconds, and more preferably less than 180 seconds. The setting time can be obtained by the method described in the Examples below.

[0044] {Glass transition point} The glass transition point of the cured product of the radically polymerizable adhesive composition of the present invention is, from the viewpoint of the heat resistance of the steel sheet laminate, for example, 60° C. or higher, and preferably 70° C. or higher. The glass transition point can be determined, for example, by the following method.

[0045] A cured product was prepared by adding 0.3 parts by mass of the following primer to 100 parts by mass of the radically polymerizable adhesive composition and injecting the mixture between two PET films spaced 1 mm apart. A sample 10 mm wide x 40 mm long was cut from the cured product and measured using a Seiko Instruments DMS6100 in a tensile mode at a temperature range of 25°C to 350°C, a heating rate of 5°C / min, and a frequency of 1 Hz to determine the peak value of tan δ, which was taken as the glass transition temperature.

[0046] {Viscosity} The viscosity of the radically polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention is not particularly limited. From the viewpoints of ease of handling and prevention of extrusion during adhesion, the viscosity may be, for example, 0.01 Pa·s or more, preferably 0.05 Pa·s or more, more preferably 0.5 Pa·s or more, and may be, for example, 50 Pa·s or less, preferably 30 Pa·s or less, more preferably 15 Pa·s or less. Viscosity can be adjusted using a viscosity adjustment method known in the adhesive field, such as blending a viscosity modifier (thixotropic agent). The viscosity can be measured, for example, by placing 100 g of the radically polymerizable adhesive composition in a bottle and discharging it into a measuring cup, using a Brookfield viscometer (manufactured by Toki Sangyo Co., Ltd.) at 25°C and 60 rpm.

[0047] (Method for producing adhesive composition) The method for producing the radical-polymerizable adhesive composition used in the method for producing a steel sheet laminate of the present invention is not particularly limited. For example, the adhesive composition can be produced by taking predetermined amounts of at least (A) a radical-polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radical-polymerizable group, and adding them to a mixing vessel in any order and mixing them.

[0048] For mixing, a mixing device such as a mixer (rotating / revolving mixer, planetary mixer, etc.), a tumbler, a stirrer, an agitator, a mechanical homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, a shaker, a V-type blender, or a Nauta mixer can be used, and it is preferable to use a mixer. The mixing conditions are not particularly limited. The temperature conditions can be, for example, 0°C or higher, preferably 10°C or higher, and for example, 100°C or lower, more preferably 70°C or lower. The mixing time can be, for example, 1 minute or longer, preferably 5 minutes or longer, and for example, 10 hours or shorter, preferably 5 hours or shorter.

[0049] <Primer containing copper compound> The primer used in the method for producing a steel sheet laminate of the present invention contains a copper compound. The primer may contain oil, a solvent, a rust inhibitor, an antiseptic, etc. in addition to the copper compound.

[0050] Examples of the copper compound include one or more compounds selected from the group consisting of copper salts of carboxylic acids such as copper neodecanoate, copper 2-ethylhexanoate, copper naphthenate, copper octenate, copper hexanoate, copper propionate, and copper 2,4-pentadionate (copper acetylacetonate); copper complexes such as ethylenediamine copper and propylenediamine copper; and the like.

[0051] As the oil, punching oil, mineral oil, synthetic oil, animal or vegetable oil, etc. can be used. In the present invention, since the step of punching steel sheets into a desired shape and the step of laminating the punched steel sheets to form a steel sheet laminate are carried out consecutively, it is preferable that the primer contains punching oil. By containing punching oil, it is possible to prevent the occurrence of galling, seizure, etc. during various processing of the steel sheets.

[0052] The solvent may be one or more organic solvents and / or water. The organic solvent is not particularly limited. Examples include one or more organic solvents selected from the group consisting of aliphatic hydrocarbon organic solvents having 5 to 40 carbon atoms (hexane, heptone, paraffin, etc.); alicyclic hydrocarbon solvents having 5 to 20 carbon atoms; aromatic hydrocarbon solvents having 6 to 20 carbon atoms (benzene, toluene, xylene, ethylbenzene, indene, etc.); alcohol solvents having 1 to 10 carbon atoms (methanol, ethanol, propanol, isopropanol, hexanol, etc.); ketone solvents having 3 to 20 carbon atoms (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.); ether solvents having 2 to 20 carbon atoms (tetrahydrofuran, diethyl ether, dioxane, ethyl cellosolve, propylene glycol monomethyl ether, etc.); and ester solvents having 2 to 20 carbon atoms (methyl acetate, ethyl acetate, butyl acetate, etc.).

[0053] The composition of the primer is not particularly limited. The copper compound is, for example, 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and for example, 15.0% by mass or less, preferably 10.0% by mass or less, more preferably 8.0% by mass or less, when the total amount of the primer is taken as 100% by mass. The oil is, for example, 20.0% by mass or more, preferably 25.0% by mass or more, more preferably 30.0% by mass or more, and for example, 80.0% by mass or less, preferably 70.0% by mass or less, more preferably 60.0% by mass or less, when the total amount of the primer is taken as 100% by mass. The solvent is used in an amount such that the total amount becomes 100% by mass.

[0054] <Steel Sheet> The steel sheet used in the method for producing the steel sheet laminate of the present invention is not particularly limited. Various steel sheets can be used depending on the application, etc. In the present invention, a steel sheet that is distributed in a rolled state can be used as is without degreasing.

[0055] Examples of steel sheets include various iron steel sheets. Among these, cold-rolled steel sheets, electromagnetic steel sheets, etc. are preferably used. In the present invention, the electromagnetic steel sheets are preferably steel sheets that are used mainly for components such as rotors and stators of motors, taking advantage of the electromagnetic properties of the steel sheets.

[0056] The thickness of the steel plate is not particularly limited and can be determined appropriately depending on the application, etc. For example, it is 0.01 mm or more, preferably 0.1 mm or more, and for example, 5 mm or less, preferably 3 mm or less, more preferably 1 mm or less. In addition, the thickness of the cured product of the radical polymerizable adhesive composition layer in the steel plate laminate is not particularly limited.

[0057] The shape of the steel sheets to be laminated is not particularly limited. In the present invention, it is preferable to form a steel sheet laminate by laminating steel sheets punched into a predetermined shape from a strip-shaped steel sheet to which the radical polymerizable adhesive composition and a primer have been applied. In particular, the magnetic steel sheet laminate can be formed by laminating, for example, two or more, preferably five or more, strip-shaped magnetic steel sheets punched into a predetermined shape.

[0058] (Steel Sheet Laminate Manufacturing Apparatus) Figure 1 shows one embodiment of a steel sheet laminate manufacturing apparatus used in the method for manufacturing a steel sheet laminate according to the present invention. In Figure 1, in the steel sheet laminate manufacturing apparatus 1, a steel strip 3 is unwound from a steel strip roll 2. A primer containing punching oil is applied to one side of the steel strip 3 by a primer application device 4A, and an adhesive is applied to the other side of the steel strip 3 by an adhesive application device 4B. After that, the steel strip 3 is introduced into a press-molding device 5. In the press-molding device 5, punching units 6A, 6B, 6C, 6D, and 6E for punching inner diameters / holes / slots, etc., can be provided as necessary to perform one or more of punching processes such as inner diameters, holes, and slots on the steel strip 3. The order of punching the inner diameters, holes, and slots is not particularly limited. After punching the inner diameter, holes, slots, etc., the steel strip 3 is subjected to an outer diameter punching punch 7 in a press molding device 5, where steel sheet laminate forming members are punched out from the steel strip 3. The punched steel sheet laminate forming members are stored in a steel sheet laminate forming member storage and holding unit 8, where the primer layer and the adhesive layer come into contact with each other to sequentially bond the steel sheet laminate forming members, and a predetermined number of steel sheet laminate forming members are stacked and bonded to form a steel sheet laminate 9. The obtained steel sheet laminate 9 is removed from the steel sheet laminate forming member storage and holding unit 8. If necessary, a heat treatment may be performed using a thermostatic bath, a far-infrared heater, or the like, for the purpose of heating to ensure the adhesive is cured. The heating conditions at this time may be, for example, a temperature of 40°C to 300°C and a time of 10 minutes to 5 hours.

[0059] In the steel plate laminate manufacturing apparatus 1 in Figure 1, a primer and an adhesive are simultaneously applied to the steel strip 3 by a primer applicator 4A and an adhesive applicator 4B, but the adhesive applicator 4B can be provided upstream of the outer diameter punching punch unit 7 (at any position before the outer diameter punching is performed). In the steel plate laminate manufacturing apparatus 1 in Figure 1, the surfaces of the punch units 6A, 6B, 6C, 6D, 6E, and 7 that punch the steel strip 3 and the surfaces of the members that make up the conveying line for the steel strip 3 may be subjected to a surface treatment (anti-adhesion treatment) to prevent adhesion of the primer and / or radical polymerizable adhesive composition applied to the steel strip 3. In the steel plate laminate manufacturing apparatus 1, it is preferable to use a primer containing punching oil (punching oil) to improve the workability of the punching process and prevent galling, seizure, etc.

[0060] In the steel plate laminate manufacturing apparatus 1 shown in FIG. 1 , punching units 6A, 6B, 6C, 6D, and 6E are provided as punching units for punching inner diameters / holes / slots, etc., but the number of punching units can be increased or decreased as needed. For example, the number of punching units can be increased to improve punching accuracy. In the steel plate laminate manufacturing apparatus 1 shown in FIG. 1 , the positions of the primer applicator 4A and the adhesive applicator 4B are not particularly limited. The primer applicator 4A can also be provided below the steel strip 3. In the steel plate laminate manufacturing apparatus 1 shown in FIG. 1 , the application method used by the primer applicator 4A and the adhesive applicator 4B is not particularly limited. For example, one or more application methods including roller coating, dispensing coating, spray coating, inkjet coating, dipping, brush coating, etc. can be used. In the steel plate laminate manufacturing apparatus 1 shown in FIG. 1 , instead of unwinding the steel strip 3 from the steel strip roll 2, a steel plate formed into a predetermined shape can also be continuously supplied to manufacture the steel plate laminate.

[0061] [Steel Sheet Laminate] The steel sheet laminate of the present invention is obtained by the [Method for Producing a Steel Sheet Laminate]. In the present invention, it is preferable to construct the steel sheet laminate using, as the steel sheet, an electromagnetic steel sheet coated with a primer containing a copper compound and a radically polymerizable adhesive composition. Also, in the present invention, it is preferable to construct the steel sheet laminate using an electromagnetic steel sheet that has been punched into a predetermined shape from a strip steel sheet.

[0062] The thickness of the steel plates used in the steel plate laminate is not particularly limited. In view of the need for thinner steel plate laminates due to the miniaturization of motors and the like, the thickness is, for example, 0.01 mm or more, preferably 0.1 mm or more, and for example, 3.0 mm or less, preferably 1.0 mm or less. The thickness of the adhesive layer (cured product of the radically polymerizable adhesive composition) when the steel plate laminate is formed is not particularly limited. For example, it is 0.1 μm or more, preferably 0.5 μm or more, and for example, 1000 μm or less, preferably 500 μm or less. The number of steel plates laminated is not particularly limited. For example, it is 2 or more, preferably 3 or more, and for example, 5000 sheets or less, for example, 3000 sheets or less, for example, 1000 sheets or less, or for example, 800 sheets or less.

[0063] In the steel sheet laminate of the present invention, particularly in a steel sheet laminate using electrical steel sheets, the cured adhesive layer functions as an insulating layer and also functions as a buffer layer for the stress of the steel sheets. When the steel sheet laminate of the present invention is used in a rotor, stator, etc. of a motor, current loss, stress concentration, and stress distortion can be reduced, making it possible to form a motor with high efficiency, high performance, and high reliability.

[0064] A motor using the steel sheet laminate of the present invention as a core of a rotor and / or a stator, etc., can be used as one or more motors selected from the group consisting of automobile drive motors, motors for adjusting the focus of cameras, drive motors for hard disks, motors built into computers, mobile terminals, mobile phones, etc.

[0065] [Adhesive composition] The adhesive composition according to the present invention is an adhesive composition for a steel sheet laminate for bonding steel sheets coated with a primer containing a copper compound, the adhesive composition containing (A) a radically polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radically polymerizable group, wherein the amount of the phosphate ester compound having a radically polymerizable group (C) is 0.055 parts by mass or more and less than 1 part by mass per 100 parts by mass of the (A) radically polymerizable compound. The adhesive composition, primer, and steel sheet are the same as those described in <Radical polymerizable adhesive composition>, <Primer containing copper compound>, and <Steel sheet> in [Method for producing a steel sheet laminate] above.

[0066] The adhesive composition of the present invention is useful for bonding various steel sheets, such as cold-rolled steel sheets and electromagnetic steel sheets, to produce steel sheet laminates. When bonding steel sheets together, particularly when bonding steel sheets having a coating containing punching oil and a copper compound formed on their surfaces, the set time (the time until the bonded steel sheets are fixed and no longer move) can be significantly shortened. The set time can be measured using the method described in the Examples below and can be, for example, less than 300 seconds, preferably less than 250 seconds, and more preferably less than 180 seconds. In steel sheet laminates produced using the adhesive composition of the present invention, particularly steel sheet laminates using electromagnetic steel sheets, the cured adhesive layer functions as an insulating layer and also as a buffer layer for the stress of the steel sheets. Therefore, when the steel sheet laminate is used in motor rotors, stators, etc., current loss, stress concentration, and stress distortion can be reduced, making it possible to produce motors with high efficiency, high performance, and high reliability.

[0067] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples. In each example, unless otherwise specified, "parts" represents "parts by mass" and "%" represents "% by mass." In addition, all descriptions relating to blending ratios in the tables are in "parts by mass."

[0068] [Constituents of Adhesive Composition] In the Examples and Comparative Examples shown in Tables 1 to 3, the constituent components of the adhesive composition are as follows. EP-MA: epoxy methacrylate (mixture of 60% by mass of epoxy methacrylate / 40% by mass of HEMA) (manufactured by DIC Corporation, "UE-8071-60BH") BPA-MA: ethylene oxide adduct of bisphenol A (approximately 2.6 mol) dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., "Light Ester BP-2EMK") PUA1: polyurethane (meth)acrylate oligomer (manufactured by Mitsubishi Chemical Corporation, "Shikou UV-1700") PUA2: polyurethane (meth)acrylate oligomer (manufactured by Mitsubishi Chemical Corporation, "Shikou UV-3700B") HEMA: hydroxyethyl methacrylate IBXMA: isobornyl methacrylate TCDDA: dimethylol-tricyclodecane diacrylate CHPO: cumene hydroperoxide PM1: monofunctional phosphate monomer (manufactured by Kyoeisha Chemical Co., Ltd., "Light Ester P-1M") PM2: Polyfunctional phosphate monomer (Kyoeisha Chemical Co., Ltd., "Light Ester P-2M") SAC: Saccharin (anaerobic catalyst) EDTA2Na: Ethylenediaminetetraacetic acid disodium salt (stabilizer)

[0069] [Evaluation of adhesive properties] <Preparation of test steel sheet> A test cold-rolled steel sheet was prepared by cutting a 0.5 mm thick cold-rolled steel sheet conforming to JIS G 3141 into a size of 25 mm wide x 100 mm long (W25mm x L100mm). A test electrical steel sheet was prepared in the same manner as in the preparation of the test cold-rolled steel sheet, except that a 0.25 mm thick electrical steel sheet (thin Hi-X Core 25HX1500, manufactured by Nippon Steel Corporation) was used instead of the cold-rolled steel sheet.

[0070] <Preparation of Primer> 0.6 parts of a 60% toluene solution of copper neodecanoate, 49.4 parts of ethanol, and 50 parts of thin plate punching oil (manufactured by Nippon Kogyo Oil Co., Ltd., "G-6338F") were mixed in a glass container to obtain a primer.

[0071] <Cold-rolled steel sheet tensile shear adhesive strength> Two cold-rolled steel sheets were prepared for testing. One sheet was spray-coated with 0.018 ml of primer and left to dry at 25°C for 3 hours. The other sheet was coated with 0.03 ml of adhesive with a spatula, and the primer-coated surface and the adhesive-coated surface were bonded together so that the adhesive area was 25 mm wide x 12.5 mm long. The two test pieces were then compressed using an air press for 200 seconds and removed to prepare a test piece (corresponding to a steel sheet laminate). The prepared test piece was aged for 24 hours in an environment of 23°C and pulled at a pulling rate of 0.5 mm / min using a universal tensile tester to measure the cold-rolled steel sheet tensile shear adhesive strength (N / mm ２ ) was obtained based on JIS K 6850 (1999).

[0072] <Cold-rolled steel sheet setting time> Two test cold-rolled steel sheets each measuring 25 mm wide and 100 mm long were prepared. 0.018 ml of primer was sprayed onto one of the longitudinal ends of one of the test cold-rolled steel sheets and allowed to dry at 25°C for 3 hours. 0.03 ml of adhesive was applied to one of the longitudinal ends of the other test cold-rolled steel sheet with a spatula. Immediately after applying the adhesive, the primer-coated surface and the adhesive-coated surface of the test cold-rolled steel sheet were bonded together so that the bonding area was 25 mm wide and 12.5 mm long. The two bonded test cold-rolled steel sheets were then compressed with an air press for a predetermined time and removed to prepare a test specimen (corresponding to a steel sheet laminate). Immediately after preparing the test piece, one of the test cold-rolled steel sheets was fixed, a 5 kg weight was hung on the other test cold-rolled steel sheet, and a tensile shear load parallel to the adhesive surface was applied. The adhesive bonded surface of the test piece (adhesive joint) was visually confirmed to be broken. The time from clamping the test piece with an air press to releasing the clamping was defined as the air press time, and the air press time when the adhesive bonded surface of the test piece no longer broke was defined as the set time. The weight was hung for 10 seconds. For example, if the test piece was clamped with an air press for 20 seconds, removed, and a 5 kg weight was immediately hung after preparation, the adhesive bonded surface of the test piece broke. On the other hand, if the test piece was clamped with an air press for 30 seconds, removed, and a 5 kg weight was immediately hung after preparation, the adhesive bonded surface of the test piece did not break, the set time was 30 seconds.

[0073] <Tensile shear adhesive strength of electrical steel sheets> Two test electrical steel sheets measuring 25 mm wide x 100 mm long were prepared. 0.018 ml of primer was sprayed onto one of the longitudinal ends of one of the test electrical steel sheets and allowed to dry at 25°C for 3 hours. 0.03 ml of adhesive was applied with a spatula to one of the longitudinal ends of the other test electrical steel sheet. Immediately after applying the adhesive, the primer-coated surface and the adhesive-coated surface of the test electrical steel sheets were bonded together so that the adhesive area was 25 mm wide x 12.5 mm long. The two bonded test electrical steel sheet laminates were then compressed in an air press for 200 seconds and removed to prepare test specimens. The prepared test specimens were aged for 24 hours in an environment of 23°C and pulled in a universal tensile tester at a tensile speed of 0.5 mm / min in a direction parallel to the adhesive surface to measure the tensile shear adhesive strength (N / mm ２ ) was obtained based on JIS K 6850 (1999).

[0074] <Electromagnetic Steel Sheet Set Time> Two test electromagnetic steel sheets, each measuring 25 mm wide and 100 mm long, were prepared. 0.018 ml of primer was sprayed onto one of the longitudinal ends of one of the test cold-rolled steel sheets and allowed to dry at 25°C for 3 hours. 0.03 ml of adhesive was applied with a spatula to one of the longitudinal ends of the other test cold-rolled steel sheet. Immediately after applying the adhesive, the primer-coated and adhesive-coated surfaces of the test electromagnetic steel sheets were bonded together to form a bonded area of ​​25 mm wide and 12.5 mm long. The two bonded test electromagnetic steel sheet laminates were then compressed in an air press for a predetermined time and removed to prepare test specimens. Immediately after preparing the test piece, one of the test cold-rolled steel sheets was fixed, a 5 kg weight was hung on the other test cold-rolled steel sheet, and a tensile shear load parallel to the adhesive surface was applied. The adhesive bonded surface of the test piece (adhesive joint) was visually confirmed to be broken. The time from clamping the test piece with an air press to releasing the clamping was the air press time, and the air press time when the adhesive bonded surface of the test piece no longer broke was the set time. The weight was hung for 10 seconds. For example, if the test piece was clamped with an air press for 20 seconds, removed, and a 5 kg weight was hung immediately after preparation, the adhesive bonded surface of the test piece broke. On the other hand, if the test piece was clamped with an air press for 30 seconds, removed, and a 5 kg weight was hung immediately after preparation, the adhesive bonded surface of the test piece did not break, the set time was 30 seconds.

[0075] Examples 1 to 5 Each of the components shown in Table 1 was taken in the amount (parts by mass) shown in Table 1 and mixed in a glass container to prepare an adhesive composition. Using the resulting adhesive composition, the cold-rolled steel sheet tensile shear bond strength, cold-rolled steel sheet set time, and electrical steel sheet tensile shear bond strength and electrical steel sheet set time were measured. The results are also shown in Table 1.

[0076] [Examples 6 to 12] Each of the components shown in Table 2 was taken in the amount (parts by mass) shown in Table 2 and mixed in a glass container to prepare an adhesive composition. Using the obtained adhesive composition, the tensile shear adhesive strength and the cold-rolled steel sheet setting time were measured. The results are also shown in Table 2.

[0077] Comparative Examples 1 to 7 Each of the components shown in Table 3 was taken in the amount (parts by mass) shown in Table 3 and mixed in a glass container to prepare an adhesive composition. Using the obtained adhesive composition, the cold-rolled steel sheet tensile shear adhesive strength and cold-rolled steel sheet set time were measured. The results are also shown in Table 3.

[0078]

[0079]

[0080]

[0081] It can be seen from Examples 1 to 5 in Table 1 and Examples 6 to 12 in Table 2 that the method for producing a steel sheet laminate and the radical polymerizable adhesive composition of the present invention exhibit excellent tensile shear adhesive strength and fast curing properties (setting time of less than 300 seconds) when a steel sheet laminate is formed using steel sheets (cold-rolled steel sheets and electromagnetic steel sheets) having punching oil on the surface.

[0082] Comparative Examples 1 to 7 in Table 3 show that when a steel sheet laminate is formed using steel sheets (cold-rolled steel sheets and electromagnetic steel sheets) having punching oil on the surface, the manufacturing method for a steel sheet laminate and the radical-polymerizable adhesive composition of the present invention are not satisfactory in terms of tensile shear bond strength and / or fast curing properties (setting time of less than 300 seconds) because the blending amount of (C) the phosphate ester compound having a radical-polymerizable group is outside the range of the present invention.

[0083] REFERENCE SIGNS LIST 1 Steel plate laminate manufacturing device, 2 Strip steel plate roll 3 Strip steel plate 4A Primer application device 4B Adhesive application device 5 Press molding device 5A Upper part of press molding device 5B Lower part of press molding device 6A, 6B, 6C, 6D, 6E Inner diameter / hole / slot etc. punching punch section 7 Outer diameter punching punch section 8 Steel plate laminate forming member storage holding section 9 Steel plate laminate

Claims

1. A method for producing a steel sheet laminate in which steel sheets coated with a primer containing a copper compound are bonded using a radically polymerizable adhesive composition containing (A) a radically polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radically polymerizable group, wherein the amount of (C) the phosphate ester compound having a radically polymerizable group is 0.055 parts by mass or more but less than 1 part by mass per 100 parts by mass of (A) the radically polymerizable compound.

2. A steel sheet stack produced by the method of claim 1.

3. An adhesive composition for a steel sheet laminate that bonds steel sheets coated with a primer containing a copper compound, the adhesive composition containing (A) a radical polymerizable compound, (B) an organic peroxide, and (C) a phosphate ester compound having a radical polymerizable group, in which the amount of (C) the phosphate ester compound having a radical polymerizable group is 0.055 parts by mass or more but less than 1 part by mass per 100 parts by mass of the (A) radical polymerizable compound.

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