KR20160063354A - Thermal curing-type magnetizable adhesive composition and adhesive sheet - Google Patents

Abstract

(A), an epoxy resin (B), a curing agent (C) and a ferromagnetic body (D), wherein the epoxy resin (B) is a cresol novolak type epoxy resin, a phenol A novolak type epoxy resin, and a bisphenol type epoxy resin. According to such a heat-curable adhesive composition, a temporary fixing force is exhibited by a magnetic force at the initial stage, and a high shear force and excellent heat resistance are obtained after heat curing.

Description

TECHNICAL FIELD [0001] The present invention relates to a thermosetting adhesive composition and a thermosetting adhesive composition,

The present invention relates to a heat curing type adhesive composition and a heat curing type adhesive layer which are suitable for bonding two or more adherends of which at least one is made of a ferromagnetic material, and a method of producing a joined body using them.

BACKGROUND ART [0002] Conventionally, an adhesive sheet is used for joining a member such as a reinforcing member to a steel sheet such as a door of an automobile, for example. If the adhesive sheet has a large adhesive force in the initial stage of the bonding, it is difficult to reattach the adhesive sheet when the alignment of the member with respect to the steel sheet is misaligned, Or the like. Accordingly, there is a demand for an adhesive sheet having excellent workability that can be temporarily fixed without depending on the adhesive force, and can be firmly adhered thereafter at the initial stage of the adhesion.

Thus, an adhesive sheet comprising an adhesive composition containing an acrylic rubber and a magnetic powder may be used. However, the adhesive sheet using the acrylic rubber in this way has a low shearing force, and there is a problem that the bonded members are displaced with time.

In contrast, Patent Document 1 proposes an adhesive sheet using an adhesive composition containing a hot-melt adhesive and a ferromagnetic substance. In order to use such an adhesive sheet, both members are fixed temporarily by interposing the adhesive sheet between one member made of a ferromagnetic material and another member made of a ferromagnetic material, and then the two members are bonded together by heating .

Patent Document 1: International Publication WO2009 / 119885

In the above-mentioned adhesive sheet, by using hot melt adhesive, the shearing force is kept high. However, if the adhesive member is placed under a high temperature, the hot-melt adhesive is softened again to lose its adhesive strength, and thus has a problem of low heat resistance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and has an object of providing a heat curable adhesive composition and a heat curable adhesive layer which exhibit a temporal fixing force by a magnetic force at the initial stage and have a high shearing force after heat curing, And a process for producing a conjugate using them.

In order to achieve the above object, first, the present invention is a heat curable adhesive composition comprising an acrylic polymer (A), an epoxy resin (B), a curing agent (C) and a ferromagnetic body (D) , Wherein the resin (B) contains at least one member selected from the group consisting of cresol novolak type epoxy resin, phenol novolak type epoxy resin and bisphenol type epoxy resin ( Invention 1).

According to the heat curable adhesive composition according to the invention (Invention 1), in the initial stage (before heat curing), the magnetic force due to the ferromagnetic substance (D) and, in some cases, the acrylic polymer (A) and the epoxy resin B exhibits a good temporary fixing force for the ferromagnetic material due to the adhesive force (preferably, a small adhesive force). After the heat curing, the adhesive force and the shearing force become high due to the cured epoxy resin (B). The adhesive obtained by heat-curing the heat-curable adhesive composition is excellent in heat resistance because it is not softened or melted even when reheated by the cured epoxy resin (B).

In the invention (Invention 1), it is preferable that the content of the ferromagnetic substance (D) in the heat-curable adhesive composition is 5 to 60% by volume (Invention 2).

In the invention (Invention 1 or 2), the content of the ferromagnetic substance (D) in the heat-curable adhesive composition is from 10 to 5000 parts by mass based on 100 parts by mass of the acrylic polymer (A) (Invention 3).

The content of the epoxy resin (B) in the heat-curable adhesive composition is preferably 5 to 3,000 parts by mass (in terms of solid content) relative to 100 parts by mass of the acrylic polymer (A) (Invention 4).

In the above inventions (inventions 1 to 4), the curing agent (C) is preferably an amine curing agent (invention 5).

Second, the present invention provides a heat-curing adhesive layer-forming adhesive sheet obtained by sheet-forming the heat-curable adhesive composition (Invention 1 to 5) (Invention 6).

In the invention (Invention 6), the thickness is preferably 0.1 to 5 mm (Invention 7).

(3) The present invention relates to a method for producing a bonded body obtained by bonding two or more adherends of which at least one is made of a ferromagnetic material, wherein the heat curable adhesive composition (inventions 1 to 5) or the heat curable adhesive layer 6, 7), the two or more adherend materials are temporarily fixed, and after the temporary fixing, the heat curable adhesive composition or the heat curable adhesive layer is heated to bond the two or more adherend materials (Claim 8).

The heat-curable adhesive composition and the heat-curable adhesive layer according to the present invention exhibit a temporary fixation force due to magnetic force at the initial stage, have a high shearing force after heat curing, and are excellent in heat resistance. Further, according to the method for manufacturing a bonded body according to the present invention, it is possible to obtain a bonded body having a high shearing force and excellent heat resistance, capable of performing bonding work with excellent workability.

Hereinafter, an embodiment of the present invention will be described.

[Heat curing type adhesive composition]

The thermosetting adhesive composition (hereinafter sometimes referred to simply as "adhesive composition") according to the present embodiment comprises an acrylic polymer (A), an epoxy resin (B), a curing agent (C) ). The epoxy resin (B) contains at least one selected from the group consisting of a cresol novolak type epoxy resin, a phenol novolak type epoxy resin and a bisphenol type epoxy resin.

The heat curing type adhesive composition containing the above components is used in the initial stage (before heat curing), the magnetic force due to the ferromagnetic substance (D), and in some cases, the adhesion by the acrylic polymer (A) and the epoxy resin (Preferably, a small adhesion force) exhibits a good temporary fixing force for the ferromagnetic material. After the heat curing, the adhesive force and the shearing force become high due to the cured epoxy resin (B). Further, the adhesive formed by heat-curing the above-mentioned components, particularly the heat curable adhesive composition containing the epoxy resin (B), is excellent in heat resistance because it is not softened or melted even after reheating. Further, since it is not melted, the thickness variation due to the magnetic force lines does not occur well.

(1) Acrylic Polymer (A)

The acrylic polymer (A) is a polymer containing (meth) acrylic acid ester as a main component as the monomer unit constituting the polymer. The term " polymer " in this specification includes the concept of " copolymer ". In the present specification, the term "(meth) acrylate" means both of an acrylate ester and a methacrylate ester. Other similar terms are also the same.

The acrylic polymer (A) contained in the heat curable adhesive composition according to the present embodiment is preferably an acrylic rubber. Herein, the term "acrylic rubber" as used herein means a homopolymer composed of a structural unit derived from a (meth) acrylic acid ester, a copolymer composed of a structural unit derived from a (meth) acrylic acid ester, and a (Meth) acrylate and a copolymer of a constituent unit derived from a polymerizable monomer other than the (meth) acrylate ester and / or a polymer thereof and a crosslinking agent (preferably a curing agent (C)), and has mechanical properties as a rubber-like elastic body. When the heat curable adhesive composition according to the present embodiment contains an acrylic rubber as the acrylic polymer (A), the heat curable adhesive composition can exhibit good flexibility. The acrylic rubber usually has little adhesive force or has a small adhesive force.

The (meth) acrylic acid ester whose main component is the acrylic polymer (A) and the monomer unit constituting the polymer is preferably a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group. By containing such (meth) acrylic acid alkyl ester, desired elasticity and / or tackiness (fine tackiness) can be expressed.

Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (Meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl Myristyl, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among them, a (meth) acrylic acid ester in which the alkyl group has 1 to 8 carbon atoms, particularly 2 to 4 carbon atoms is preferable, and a (meth) acrylate and a (meth) Particularly preferred. These may be used alone or in combination of two or more.

The acrylic polymer (A) preferably contains 50 to 100 mass%, particularly preferably 75 to 99 mass%, of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as the monomer unit constituting the polymer By mass, more preferably from 92 to 98% by mass.

The acrylic polymer (A) may contain a monomer having a functional group as a monomer unit constituting the polymer so as to impart desired physical properties to the resulting adhesive composition or the cured adhesive, and in particular, a crosslinking agent (preferably a curing agent It is preferable to contain a monomer having a functional group (functional group-containing monomer) which reacts. By containing such a functional group-containing monomer, the obtained acrylic polymer (A) exhibits good elasticity by being crosslinked (usually by heat molding of an adhesive composition) with a crosslinking agent (curing agent (C)). Further, in the adhesive after curing, it is presumed that the acrylic polymer (A) having the crosslinked structure (three-dimensional network structure) bonds with the epoxy resin (B) through the curing agent (C) and is entangled with each other. With this structure, the cured adhesive exhibits excellent heat resistance.

Examples of the functional group of the functional group-containing monomer include a carboxyl group, a hydroxyl group, an epoxy group, a halogen, and the like. Particularly, when the crosslinking agent (preferably the curing agent (C)) is an amine-based curing agent, a carboxyl group having high reactivity with an amine is preferable.

Examples of the monomer having a carboxyl group (carboxyl group-containing monomer) include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid, Krylic acid is preferred, and acrylic acid is particularly preferred. These may be used alone or in combination of two or more.

When the curing agent (C) is an amine-based curing agent, the acrylic polymer (A) preferably contains 0.1 to 10 mass% of a carboxyl group-containing monomer as a monomer unit constituting the polymer, more preferably 1 to 5 mass% By mass, more preferably from 2 to 4% by mass. When the content of the carboxyl group-containing monomer is 0.1% by mass or more, the above-mentioned effect by crosslinking is satisfactorily obtained. When the content of the carboxyl group-containing monomer is 10 mass% or less, the flexibility of the heat curable adhesive composition can be maintained even after crosslinking.

The acrylic polymer (A) may contain other monomers such as (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl methacrylate and ethoxyethyl (meth) acrylate, acrylamide, (Meth) acrylic acid esters having a non-crosslinkable tertiary amino group such as (meth) acrylic acid N, N-dimethylaminoethyl and (meth) acrylic acid N, N-dimethylaminopropyl, (Meth) acrylic acid ester having an aliphatic ring such as cyclohexyl (meth) acrylate and phenyl (meth) acrylate, a (meth) acrylate ester having an aromatic ring, vinyl acetate, styrene and the like.

The polymerization of the acrylic polymer (A) may be a random copolymer or a block copolymer.

The mass average molecular weight (Mw) of the acrylic polymer (A) is preferably from 500,000 to 2,500,000, particularly preferably from 800,000 to 2,000,000, and further preferably from 1,000,000 to 1,500,000. In the present specification, the mass average molecular weight is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC).

When the mass average molecular weight of the acrylic polymer (A) is 500,000 or more, adhesion of the obtained adhesive composition before curing is suppressed, and when the mass average molecular weight is 2.5 million or less, adhesion of the obtained adhesive composition before curing is easily peeled off by hand It will be enough. Therefore, when the mass average molecular weight of the acrylic polymer (A) is within the above range, a desirable adhesive force for temporary fixing can be obtained.

In the heat curable adhesive composition according to the present embodiment, the acrylic polymer (A) may be used singly or in combination of two or more kinds.

(2) Epoxy resin (B)

The epoxy resin (B) contained in the heat curable adhesive composition according to the present embodiment contains at least one selected from the group consisting of cresol novolak type epoxy resin, phenol novolak type epoxy resin and bisphenol type epoxy resin do. As a result, the adhesive after curing the adhesive composition exhibits a desired adhesive force, shearing force, and heat resistance.

As the cresol novolak type epoxy resin, for example, those represented by the following formulas can be used.

[Chemical Formula 1]

(Wherein n is an integer of 1 to 60)

The cresol novolak type epoxy resin preferably has a mass average molecular weight of 1,000 to 10,000, more preferably 1,500 to 5,000. The epoxy equivalent is preferably 100 to 300 g / eq, more preferably 200 to 230 g / eq. Further, the softening point is preferably 30 to 150 ° C, more preferably 50 to 100 ° C.

As the phenol novolak type epoxy resin, for example, those represented by the following formulas can be used.

(2)

(Wherein n is an integer of 1 to 60)

The phenol novolak type epoxy resin preferably has a mass average molecular weight of 500 to 10,000, more preferably 1,000 to 3,000. The epoxy equivalent is preferably 100 to 300 g / eq, more preferably 170 to 210 g / eq. Further, it is preferably semi-solid at room temperature.

Examples of the bisphenol type epoxy resin include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a bisphenol AD type epoxy resin. Among them, a bisphenol A type epoxy resin is preferable.

As the bisphenol A type epoxy resin, for example, those represented by the following formulas can be used.

(3)

(Wherein n is an integer of 1 to 80)

The bisphenol type epoxy resin preferably has a mass average molecular weight of 1,000 to 20,000, more preferably 3,000 to 8,000. The epoxy equivalent is preferably 400 to 1300 g / eq, more preferably 700 to 1000 g / eq. Further, the softening point is preferably 50 to 150 ° C, more preferably 80 to 100 ° C.

Among them, cresol novolak type epoxy resin and phenol novolak type epoxy resin are preferable, and phenol novolak type epoxy resin is particularly preferable. According to the cresol novolak type epoxy resin and the phenol novolak type epoxy resin, especially the phenol novolak type epoxy resin, the cured adhesive exhibits excellent adhesive force and shearing force, and the adhesive composition before curing exhibits good flexibility. Particularly, since the phenol novolak type epoxy resin is semi-solid at room temperature, the effect of flexibility is remarkable. Further, when the acrylic polymer (A) is an acrylic rubber, the adhesive composition is more flexible because of its combination with the acrylic rubber. Thus, for example, when the heat-curable adhesive composition according to the present embodiment is formed into a sheet, the sheet-like adhesive composition can be favorably followed on a three-dimensional curved surface. Further, even when a bisphenol-type epoxy resin (preferably a bisphenol A-type epoxy resin) is used as the epoxy resin (B), the flexibility of the adhesive composition can be secured by adjusting the blending amount to a small amount.

The epoxy resin (B) may be used singly or in combination of two or more kinds. In order to balance the shearing force before the curing and the shearing force after the curing, it is preferable that the epoxy resin (B) It is particularly preferable to contain both a solid epoxy resin and a semi-hard epoxy resin at room temperature.

The content of the epoxy resin (B) in the heat-curable adhesive composition according to the present embodiment is preferably 5 to 3000 parts by mass, more preferably 10 to 2000 parts by mass based on 100 parts by mass of the acrylic polymer (A) And more preferably 30 to 500 parts by mass. When the content of the epoxy resin (B) is 5 parts by mass or more, the above effect of the epoxy resin (B) is excellently exerted. When the content of the epoxy resin (B) is 3,000 parts by mass or less, the inhibition of the elasticity by the acrylic polymer (A) is suppressed.

(3) Hardener (C)

The curing agent (C) contained in the heat curable adhesive composition according to the present embodiment is capable of curing the epoxy resin (B) by heating. When the acrylic polymer (A) has a functional group reactive with the curing agent (C), the acrylic polymer (A) is crosslinked.

As such a curing agent (C), a compound having at least two functional groups capable of reacting with an epoxy group in one molecule is preferably used. Examples of the functional group include a phenolic hydroxyl group, an alcoholic hydroxyl group, an amino group, a carboxyl group, and an acid anhydride. Of these, an amino group and a phenolic hydroxyl group are preferable, and an amino group is particularly preferable. That is, as the curing agent (C), an amine-based curing agent and a phenol-based curing agent are preferable, and an amine-based curing agent is particularly preferable. The amine-based curing agent has high reactivity with the epoxy resin (B), and also has high reactivity with the acrylic polymer (A) when the acrylic polymer (A) has a carboxyl group. Furthermore, the acrylic polymer (A) crosslinked by the amine-based curing agent is particularly excellent in heat resistance.

Examples of the amine curing agent include aromatic dicarboxylic acids such as dicyandiamide, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylsulfone, m-phenylenediamine and m- Amine, etc. Among them, dicyandiamide is preferable. Examples of the phenol-based curing agent include phenol novolac resins, bisphenol A-type novolac resins, and triazine-modified phenol novolac resins.

The curing agent (C) may be used singly or in combination of two or more.

The content of the curing agent (C) in the heat curable adhesive composition according to the present embodiment is preferably 0.02 to 15 parts by mass, more preferably 0.1 to 10 parts by mass (in terms of solid content) relative to 100 parts by mass of the epoxy resin And more preferably 0.3 to 4 parts by mass. When the content of the curing agent (C) is 0.02 parts by mass or more, the curing of the epoxy resin (B) (and crosslinking of the acrylic polymer (A)) is satisfactorily achieved. On the other hand, if the content of the curing agent (C) is excessively large, there is a fear that the curing agent (C) remains unnecessarily in the adhesive and is economically disadvantageous.

(4) Curing catalyst

The heat curable adhesive composition according to the present embodiment preferably contains a curing catalyst for promoting or controlling the reaction between the epoxy resin (B) and the curing agent (C).

As the curing catalyst, for example, tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol and tris (dimethylaminomethyl) phenol; 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl- Imidazoles such as hydroxymethylimidazole; Organic phosphines such as tributylphosphine, diphenylphosphine and triphenylphosphine; And tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate. Of these, imidazoles are preferable, and 2-phenyl-4,5-dihydroxymethylimidazole is particularly preferably used. These may be used singly or in combination of two or more.

The content of the curing catalyst in the heat curable adhesive composition according to the present embodiment is preferably 0.01 to 7 parts by mass with respect to 100 parts by mass of the total amount of the epoxy resin (B) and the curing agent (C) It is preferably 0.05 to 5 parts by mass, more preferably 0.15 to 2 parts by mass.

(5) Ferromagnetic material (D)

The ferromagnetic material (D) used in the heat curable adhesive composition according to the present embodiment is a material capable of spontaneous magnetization without an external magnetic field, and includes a ferrimagnetic material. Specific examples of the ferromagnetic material (D) include metals such as iron, nickel, and cobalt, alloys thereof (such as stainless steel) or oxides, or strontium ferrite, barium ferrite, manganese zinc ferrite, nickel zinc ferrite, And ferrite-based alloys such as aluminum-nickel-cobalt alloys and rare earth-based alloys such as rare earth-transition metal alloys such as SmCo, SmFeN and NbFeB. Of these, ferrite based alloys are preferable from the viewpoint of easy control of initial magnetic properties, and among them, strontium ferrite and barium ferrite are more preferable.

The ferromagnetic body D is preferably a powder (hereinafter referred to as " magnetic powder "). The average particle diameter of the magnetic powder is preferably 0.5 to 20 탆, more preferably 0.5 to 15 탆, further preferably 1 to 5 탆. The average particle diameter of the magnetic powder can be measured by, for example, a Coulter counter method.

The content of the ferromagnetic material (D) (magnetic powder) in the heat curable adhesive composition according to the present embodiment is preferably 5 to 60% by volume, more preferably 10 to 50% by volume, 40% by volume is preferable. When the content of the ferromagnetic material (D) is 5 vol% or more, temporary fixing force for the ferromagnetic material is exhibited by the magnetic force by the ferromagnetic material (D) at the initial stage (before heat curing). On the other hand, when the content of the ferromagnetic material (D) is 60 vol% or less, the action and effect of the other components, particularly the flexibility and the shear force, are inhibited.

The content of the ferromagnetic substance (D) in the heat-curable adhesive composition according to the present embodiment is preferably 10 to 5000 parts by mass, more preferably 50 to 2000 parts by mass based on 100 parts by mass of the acrylic polymer (A) By mass, more preferably from 150 to 700 parts by mass. When the content of the ferromagnetic material (D) is 10 parts by mass or more, temporary fixing force against the ferromagnetic material is exhibited by the magnetic force by the ferromagnetic body (D) in the initial stage (before heat curing). On the other hand, when the content of the ferromagnetic body (D) is 5,000 parts by mass or less, the flexibility is not excessively high and the sufficient shearing force can be maintained.

(6) Other components

The heat curable adhesive composition according to the present embodiment may suitably contain at least one of a crosslinking agent, a tackifier, an antioxidant, a filler, a dispersant and the like in addition to the above components.

(7) Method for producing a heat curable adhesive composition

To prepare the heat curable adhesive composition according to the present embodiment, an acrylic polymer (A), an epoxy resin (B), a curing agent (C), a ferromagnetic substance (D), preferably a curing catalyst and other components . At this time, by heating the mixture at about 20 to 120 DEG C, each component is well dispersed.

As described above, the ferromagnetic material (D) to be mixed with the heat curable adhesive composition may be in a magnetized state or in a state in which it is not yet magnetized. In the latter case, after the mixing, the adhesive composition is obtained and then magnetized (magnetized). The magnetization can be carried out by a well-known method and can be carried out, for example, by using a commercially available magnetizing / demagnetizing power supply device or the like.

(8) Effects and uses of a heat-curable self-adhesive adhesive composition

As described above, the heat-curable adhesive composition according to the present embodiment exhibits excellent temporal properties for the ferromagnetic material due to the magnetic force and, in some cases, the adhesive force (preferably, a small adhesive force) at the initial stage It shows fixing force. The adhesive obtained by heat-curing the heat-curable adhesive composition according to the present embodiment exhibits a high shearing force. Further, since the adhesive is not softened or melted even when reheating, the heat resistance is excellent, and further, the thickness is not changed by the magnetic force lines. In particular, when the heat curable adhesive composition according to the present embodiment contains an acrylic rubber and an epoxy resin (B) which are semi-solid at room temperature as the acrylic polymer (A), they can be followed to a three- have.

The heat curable adhesive composition according to the present embodiment is used for bonding two or more members (adherend) of which at least one is made of a ferromagnetic material. Examples of members made of a material exhibiting ferromagnetism include members made of a material containing iron, cobalt, nickel, and the like. In addition, the heat-curable adhesive composition according to the present embodiment is preferably used for a portion which becomes high in temperature since it has high heat resistance after curing. Concretely, it is possible to use a steel plate of an automobile door or a body, a hole plate of the steel plate, an automobile part such as a reinforcing part of a car body, especially near a heat generating part such as an engine or an exhaust pipe; Steel parts in structures such as buildings; Precision parts, electronic parts, and the like, particularly in the vicinity of the heat generating part in such devices.

The thermosetting adhesive composition according to the present embodiment can be molded into a predetermined shape required for bonding the above members together. Specific examples of the shape include a polygonal shape such as a triangle, a quadrangle, a pentagon, a hexagon, an octagon, etc., a circular shape such as a circle, an ellipse, and a ring shape obtained by removing the center of these shapes. A thermosetting adhesive type adhesive sheet), a plate, a block, a column, a rod, and the like.

Here, when the acrylic polymer (A) of the heat curable adhesive composition according to the present embodiment has a functional group reactive with the crosslinking agent (curing agent (C)), when the heat curable adhesive composition is thermally formed, (A) is crosslinked. The heating temperature at this time is preferably 20 to 120 占 폚, particularly preferably 40 to 80 占 폚.

The heating temperature at the time of adhering the adherend with the heat-curable adhesive composition according to the present embodiment is preferably 70 to 250 ° C, more preferably 130 to 200 ° C. By heating at such a temperature, the heat-curable adhesive composition according to the present embodiment is cured and exhibits a high adhesive force, thereby firmly bonding the adherend.

[Heat curing type adhesive sheet]

The heat-curable adhesive layer according to the present embodiment is obtained by forming the heat-curable adhesive layer composition into a sheet. The thickness of the heat-curable adhesive layer varies depending on the application, but it is preferably 0.1 to 5 mm, more preferably 0.2 to 3 mm, further preferably 0.3 to 2 mm.

The production method of the heat-curable adhesive layer according to the present embodiment is not particularly limited, but the heat-curable adhesive composition described above can be preferably produced by hot pressing. The temperature of the hot press is preferably 20 to 120 ° C, more preferably 40 to 80 ° C. When the acrylic polymer (A) of the heat curable adhesive composition according to the present embodiment has a functional group reactive with a crosslinking agent (curing agent (C)), the acrylic polymer (A) is crosslinked by the hot press described above .

As described above, it is preferable to sandwich the heat curable adhesive composition with two release sheets so that the release sheet is laminated on both sides of the obtained heat curable adhesive layer. The peeling sheet may be a peeling sheet which has been peeled off on both sides or a peeling sheet whose one surface has been peeled off. The peeling sheet is used so that the peeling treatment surface is the side of the heat-setting type adhesive layer.

Examples of the peeling sheet include a polyester resin film such as a polyethylene terephthalate resin, a polybutylene terephthalate resin and a polyethylene naphthalate resin; a plastic film such as a polyolefin resin film such as a polypropylene resin or a polyethylene resin; Or a laminate paper obtained by laminating a thermoplastic resin such as polyethylene on a paper base material such as a glasin (paper), a coated paper, a coated paper or the like, with a releasing agent such as a silicone resin applied. The thickness of the release sheet is not particularly limited, but is preferably 20 to 200 탆.

The heat-curable adhesive layer according to the present embodiment has high adhesive strength after heat curing and is excellent in heat resistance because it is not softened or melted even after reheating. And, since it is not melted after the heating and curing, the thickness change due to the magnetic force lines does not occur.

The shearing force of the heat-curable adhesive layer according to the present embodiment after heat bonding is preferably 80 N / cm2 or more, more preferably 120 N / cm2 or more, and further preferably 200 N / cm2 or more. Here, the shearing force after heat bonding in the present specification means a state in which one side of the heat-curing type adhesive layer is adhered to a stainless steel plate (thickness: 0.5 mm) and the other side is covered with another stainless steel plate ), Heated at 150 ° C for 40 minutes, returned to room temperature, and measured according to JIS K 6850 (test speed 50 mm / min).

The heat-curable adhesive layer of the heat curable adhesive sheet according to the present embodiment can achieve a high shearing force as described above because the heat curable adhesive composition contains the epoxy resin (B). According to the heat-curable adhesive sheet having such a shearing force, it is possible to effectively prevent the adhesive members from being displaced with time or the like.

It is preferable that the surface-curing adhesive sheet according to the present embodiment has a surface magnetic force of 1 mT or more at room temperature, more preferably 3 to 100 mT, further preferably 5 to 50 mT. Here, the surface magnetic force in this specification refers to the surface magnetic force measured by a gauss meter at a distance of 1 cm from the surface of the heat-curable adhesive sheet having a thickness of 1 mm. If the surface magnetic force is 1 mT or more, the member made of the ferromagnetic material can be sufficiently temporarily fixed. If the surface magnetic force is 100 mT or less, the position can be easily corrected even if the temporary fixing position deviates from the predetermined position.

The heat-curable adhesive layer according to the present embodiment preferably has a degree of laminating of 10 to 2000 mN, more preferably 50 to 1500 mN, further preferably 100 to 800 mN. Here, the laydowns in this specification were measured for a heat-curable adhesive sheet having a length of 38 mm and a width of 25 mm in accordance with Jurisdiction of JIS L 1096 (1999) 8.20.1 using a lapping tester It is a lecture.

The heat-curable adhesive layer of the heat curable adhesive sheet according to the present embodiment can achieve the above-mentioned curability by containing the acrylic rubber as the acrylic polymer (A). The thermosetting adhesive layer having such a degree of lubrication exhibits excellent flexibility, and even if the object to be adhered has a three-dimensional curved surface, the adherend can be surely adhered to the adherend.

The heat curable adhesive sheet according to the present embodiment can also be used for the same purpose as the heat curable adhesive composition described above.

[Process for producing a bonded body]

Hereinafter, a method of manufacturing a bonded body according to one embodiment of the present invention will be described.

A method of manufacturing a bonded body according to the present embodiment is a method of manufacturing a bonded body by bonding at least two of the object to be bonded with at least one ferromagnetic material. First, two or more adherends are temporarily fixed using the above-mentioned heat-curable adhesive composition or the heat-curable adhesive layer, and then the above-mentioned heat-curable adhesive composition or the heat-curable adhesive layer is heated , The two or more adherends are bonded. More specifically, the following method is exemplified.

As a first example, a description will be given of a method of bonding a first member made of a ferromagnetic material and a second member made of a ferromagnetic material to the bonding surfaces of the first and second members via the heat-curable adhesive sheet. First, a heat-curable adhesive layer having a shape of a bonding surface between the first member and the second member is prepared. The thermosetting adhesive layer is sandwiched between the joining surfaces of the two members and the first member and the second member are temporarily fixed by the magnetic force (and adhesive force) of the heat-setting adhesive layer. As a result, the workability becomes good. Then, the heating and curing type adhesive layer is heated and then cooled to firmly bond the first member and the second member to obtain a bonded body. The shapes of the first member and the second member are not particularly limited.

As a second example, a description will be given of a method of bonding a first member and a second member made of a ferromagnetic material to a bonding surface of the first member via a heat-curable adhesive composition. First, an adhesive portion comprising a heat-curable adhesive composition is formed on the first member. As a method of forming the adhesive portion, a heat curable adhesive composition may be coated on the first member, or the first member may be stacked on the heat curable adhesive composition. The first member may be a ferromagnetic substance or may not be a ferromagnetic substance.

Subsequently, the adhesive portion formed on the first member is attracted to the second member by the magnetic force (and adhesive force) of the adhesive portion to temporarily fix the first member and the second member. As a result, the workability becomes good. Then, the heat curable adhesive composition is heated and then cooled to firmly bond the first member and the second member to obtain a bonded body.

The adhesives in the bonded body obtained as described above are excellent in heat resistance because they have high adhesive force and shearing force and are not softened or melted even after reheating. Further, since the adhesive is not melted, the thickness change due to the magnetic force lines does not occur.

 The embodiments described above are provided for the purpose of facilitating understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents falling within the technical scope of the present invention.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]

A mass average molecular weight of 1.3 million, a molecular weight distribution of 2.70 (produced by copolymerizing ethyl acrylate (EA), n-butyl (meth) acrylate (BA) and acrylic acid (AA) in a mass ratio of 37: Of acrylic rubber were prepared.

100 parts by mass of the acrylic polymer (A) (in terms of solid content; hereinafter the same) and a cresol novolak epoxy resin (product name: "N-660", epoxy equivalent: 200 to 215 g / eq., softening point: 61 to 69 占 폚, solid), 0.68 parts by mass of dicyanamide as the curing agent (C), and 0.34 parts by mass of 2-phenyl-4,5-dihydroxymethylimidazole as a curing catalyst And 230 parts by mass (29% by volume) of strontium ferrite powder (average particle diameter 2 μm) as the ferromagnetic body D were placed in a mixer (product name "30C150" manufactured by Toyoda Seiki Seisakusho) To obtain a heat curable adhesive composition.

On the other hand, as a release sheet, two release sheets (product name: "SP-PET381130", thickness: 38 μm) having one side of the polyethylene terephthalate film peeled off with a silicone release agent were prepared. The heat curable adhesive composition thus obtained was sandwiched by the two release sheets and a hot press machine (manufactured by Tester Ind. Co., Ltd., product name: " SA " -302 ", heating temperature: 60 占 폚) to form a sheet having a thickness of 1 mm, and then subjected to magnetization using a mold in a magnetic field to obtain a heat curable adhesive sheet laminated with release sheets on both surfaces.

[Examples 2 to 28, Comparative Examples 1 to 2]

Except that the types and blending amounts of the components constituting the heat curable adhesive composition and the thickness of the heat curable adhesive layer were changed as shown in Table 1, the heat curable adhesive layer . In Examples 20 to 23, two kinds of epoxy resins (B) (epoxy resin (B) -1 and epoxy resin (B) -2) were used.

Details of the epoxy resin (B) (epoxy resin (B) -1 and epoxy resin (B) -2) shown in Table 1 are as follows.

N-660 ": cresol novolak type epoxy resin (product name" N-660 ", epoxy equivalent: 200 to 215 g / eq, softening point: 61 to 69 ° C, mass average molecular weight:

(EOCN-104S, epoxy equivalent: 213 to 223 g / eq, softening point: 90 to 94 占 폚, mass average molecular weight: 3600, solid type )

N-740 ": phenol novolak type epoxy resin (product name" N-740 ", epoxy equivalent: 170 to 190 g / eq, mass average molecular weight: 1600,

1055 ": Bisphenol A type epoxy resin (product name: " 1055 ", epoxy equivalent weight: 800 to 900 g / eq; softening point: 93 캜, mass average molecular weight:

[Test Example 1] (Shearing force measurement)

The heat curable adhesive layer obtained in Examples and Comparative Examples was cut into squares of 1 cm x 1 cm. Then, one of the release sheets was peeled off, and the heat-curable adhesive sheet was stuck to a stainless steel plate (SUS430 (2B) # 280HL, thickness 0.5 mm). Next, the other release sheet was peeled off, and the heat-curable adhesive sheet was attached to a separately prepared stainless steel plate (thickness: 0.5 mm), heated at 150 캜 for 40 minutes, and returned to room temperature. With respect to the adhesive thus cured by heating, the other stainless steel plate was fixed at a test speed of 50 mm / min while fixing one stainless steel sheet in accordance with JIS K 6850 using a material tester (product name "5581" manufactured by Instron) The shear force (N / cm2) was measured by moving. The results are shown in Table 1.

[Test Example 2] (Measurement of surface magnetic force)

One of the release sheets was peeled off from the thermosetting adhesive type adhesive sheet obtained in the Examples and Comparative Examples, and the thermosetting adhesive sheet was peeled off at a distance of 1 cm from the surface of the exposed thermosetting adhesive type adhesive sheet using a gaussmeter (product name: " 5080 Quot; Handy Gaussmeter ") to measure the surface magnetic force (mT) at room temperature. The results are shown in Table 1.

[Test Example 3] (Measurement of lubrication degree)

The thermosetting adhesive layer obtained in Examples and Comparative Examples was cut to a length of 38 mm and a width of 25 mm and the release sheets on both sides were peeled off and used as measurement samples. (MN) was measured on the sample for measurement according to the Jurassic method of JIS L 1096 (1999) 8.20.1 using a lapping tester (manufactured by TOYO SEIKI Co., Ltd., product name "Gullibility Flexibility Tester" . The results are shown in Table 1.

As can be seen from Table 1, the heat-curable adhesive layer obtained in the examples had a good surface magnetic force and exhibited a high shear force after heat curing. In addition, the heat curable adhesive sheets obtained in Examples 1 to 23 and 25 to 28 had low flexibility and excellent flexibility.

Industrial availability

INDUSTRIAL APPLICABILITY The present invention can be suitably used for joining members made of a ferromagnetic material or for joining members made of a ferromagnetic material.

Claims (8)

The acrylic polymer (A)
An epoxy resin (B)
A curing agent (C)
The ferromagnetic material (D)
Wherein the thermosetting adhesive composition is a thermosetting adhesive composition,
Wherein the epoxy resin (B) contains at least one member selected from the group consisting of a cresol novolak type epoxy resin, a phenol novolak type epoxy resin and a bisphenol type epoxy resin. The method according to claim 1,
Wherein the content of the ferromagnetic material (D) in the heat-curable adhesive composition is from 5 to 60% by volume. The method according to claim 1,
Wherein the content of the ferromagnetic material (D) in the heat-curable adhesive composition is 10 to 5000 parts by mass based on 100 parts by mass of the acrylic polymer (A) in terms of solid content. The method according to claim 1,
Wherein the content of the epoxy resin (B) in the heat-curable adhesive composition is 5 to 3000 parts by mass based on 100 parts by mass of the acrylic polymer (A) in terms of solid content. The method according to claim 1,
Wherein the curing agent (C) is an amine-based curing agent. A heat-curing adhesive layer-forming adhesive sheet obtained by sheet-forming the heat-curable adhesive composition according to claim 1. The method according to claim 6,
Wherein the adhesive layer has a thickness of 0.1 to 5 mm. A method of producing a bonded body obtained by bonding at least two objects to be bonded with each other, the at least one object being made of a ferromagnetic material,
A thermosetting adhesive composition according to any one of claims 1 to 5 or a heat-curing adhesive layer according to any one of claims 6 to 7, wherein the two or more adherends are temporarily fixed,
Wherein the heat curable adhesive composition or the heat curable adhesive layer is heated after the provisional fixation to bond the two or more adherends.