JP2011236322A - Structural adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structural adhesive suppressing lowering of physical properties, not causing increase of viscosity and specific gravity and applicable of electrodeposition coating on the cured surface thereof.SOLUTION: This structural adhesive includes an epoxy resin and a latent curing agent as principal components, and contains at least an alginate as conductive agents, where the content of the alginate is 0.1-30 pts.mass to 100 pts.mass of the epoxy resin. Thus, the adhesive suppresses lowering of physical properties to the minimum, provides electrodeposition coatability without causing increase of viscosity and specific gravity, maintains close adhesion with adherend members such as a substrate and excels in corrosion resistance.

Description

  The present invention relates to a structural adhesive.

  When electrodeposition coating is applied to a metal structure such as a car body constructed using an adhesive, the adhesive is an insulator on the exposed surface of the cured adhesive. I can't. For this reason, rust is likely to occur at the exposed portion of the surface of the cured adhesive in the metal structure.

  Conventionally, an adhesive to which powder such as metal having conductivity is added has been proposed. For example, Patent Document 1 describes a conductive adhesive in which carbon black is blended with a vinyl chloride-vinyl acetate copolymer. Patent Document 2 describes a conductive resin composition in which a conductive filler is added to a resinous material. Patent Document 3 describes a conductive adhesive composition in which a conductive metal such as silver, copper, aluminum, palladium, nickel, or iron is added to an epoxy resin.

  A composition in which such conductive powder or the like is added to a resin such as an epoxy resin is used to perform electrodeposition coating on the surface of the cured adhesive.

JP 59-81366 A JP-T-2001-503471 JP-T-2006-514144

  Here, in order to impart conductivity to the resin, it is necessary to contain a large amount of the powder in the resin. However, if a large amount of the powder is contained in the resin, the physical properties and viscosity of the adhesive are reduced. There was a problem that the increase in specific gravity and the specific gravity would occur. Since the shear strength and peel strength of the adhesive are lowered and the physical properties as the adhesive are lowered, it is not preferable. Further, when the viscosity of the adhesive increases, workability deteriorates, and when the specific gravity of the adhesive increases, the weight of the resulting composition increases, which is not preferable. Therefore, an adhesive that suppresses an increase in viscosity and an increase in specific gravity without reducing physical properties is desired.

  An object of the present invention is to provide a structural adhesive that can suppress the deterioration of physical properties and can perform electrodeposition coating on a cured surface without increasing the viscosity and specific gravity.

The present invention includes the following (1) to (3).
(1) The main component is an epoxy resin and a latent curing agent, and at least an alginate is included as a conductive agent.
Content of the said alginate is 0.1 to 30 mass parts with respect to 100 mass parts of said epoxy resins, The structural adhesive agent characterized by the above-mentioned.
(2) The conductive agent further contains carbon black,
The structural adhesive as described in (1) above, wherein the carbon black is contained in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the epoxy resin.
(3) The structural adhesive according to (1) or (2) above, wherein the alginate is a sodium salt.

  According to the present invention, it is possible to perform electrodeposition coating on the cured surface without suppressing a decrease in physical properties and without increasing the viscosity and specific gravity. For this reason, it is possible to provide a structural adhesive that has electrodeposition coating properties, maintains adhesion to a member to be bonded such as a substrate, and is excellent in corrosion resistance.

  The present invention will be described in detail below. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  The structural adhesive of the present invention will be described. The present invention comprises an epoxy resin and a latent curing agent as main components, and contains at least an alginate as a conductive agent, and the content of the alginate is 0.1 part by mass or more and 30 parts by mass with respect to 100 parts by mass of the epoxy resin. It is a structural adhesive having a mass part or less. Hereinafter, the structural adhesive of the present invention is referred to as “the adhesive of the present invention”. The adhesive of the present invention is obtained by heating and curing the epoxy resin composition obtained by mixing various components as described above.

  In the present invention, the “main component” means 60 parts by mass or more. That is, the total content of the epoxy resin and the latent curing agent in the adhesive of the present invention is 60 parts by mass or more. This ratio is preferably 70 parts by mass or more, and more preferably 80 parts by mass or more. In the present invention, the “structural adhesive” refers to an adhesive (JIS K6800) that is less likely to deteriorate the adhesive properties even when a large load is applied for a long time and has high reliability.

<Epoxy resin>
The epoxy resin will be described. The epoxy resin contained in the adhesive of the present invention is not particularly limited as long as it is a compound having two or more epoxy groups. Examples of the epoxy resin include bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, and biphenyl type epoxy compounds, polyalkylenes, and the like. Bifunctional glycidyl ether type epoxy resins such as glycol type, alkylene glycol type epoxy compounds, epoxy compounds having a naphthalene ring, epoxy compounds having a fluorene group; phenol novolac type, orthocresol novolak type, trishydroxyphenylmethane type, Polyfunctional glycidyl ether type epoxy resin such as tetraphenylolethane type; Glycidyl ester type epoxy resin of synthetic fatty acid such as dimer acid; N, N, N ′, N′-tetraglyce Aromatic epoxy resins having a glycidylamino group such as dildiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N, N-diglycidylaniline; having a tricyclodecane ring An epoxy compound (for example, an epoxy compound obtained by a production method in which epichlorohydrin is reacted after polymerizing cresols or phenols such as dicyclopentadiene and m-cresol) and the like. Moreover, for example, an epoxy resin having a sulfur atom in the main chain of the epoxy resin, such as Flep 10 manufactured by Toray Fine Chemical Co., Ltd., can be mentioned. The epoxy resins can be used alone or in combination of two or more.

  Among these, bisphenol A type and / or bisphenol F type are preferable. The amount of bisphenol A-type epoxy resin and / or bisphenol F-type epoxy resin is preferably greater than 0 parts by mass and less than or equal to 100 parts by mass, more than 0 parts by mass and less than or equal to 70 parts by mass. More preferably. This is because it is easy to adjust the viscosity of the composition. In the present invention, the contents of the bisphenol A type epoxy resin and the bisphenol F type epoxy resin are additive amounts.

(Rubber-modified epoxy resin)
Moreover, a rubber modified epoxy resin is mentioned as a preferable aspect of an epoxy resin. The rubber-modified epoxy resin is not particularly limited as long as it is an epoxy resin having two or more epoxy groups and a skeleton of rubber. Examples of the rubber forming the skeleton include polybutadiene, acrylonitrile butadiene rubber (NBR), and carboxyl group-terminated NBR (CTBN). The rubber-modified epoxy resins can be used alone or in combination of two or more. The amount of the rubber-modified epoxy resin is preferably greater than 0 parts by mass and 100 parts by mass or less, more preferably greater than 0 parts by mass and 60 parts by mass or less in the epoxy resin. This is because the balance between peel strength and shear strength is improved.

  The rubber-modified epoxy resin is not particularly limited for its production. For example, it can be produced by reacting rubber and epoxy in a large amount of epoxy. The epoxy (for example, epoxy resin) used when producing the rubber-modified epoxy resin is not particularly limited. For example, a conventionally well-known thing is mentioned. In the present invention, the addition amount of the rubber-modified epoxy resin is the addition amount in the rubber-modified epoxy resin containing an excessive epoxy resin used at the time of production.

(Urethane-modified epoxy resin)
Moreover, urethane modified epoxy resin is mentioned as a preferable aspect of an epoxy resin.
The structure of the urethane-modified epoxy resin is not particularly limited as long as it is a resin having a urethane bond and two or more epoxy groups in the molecule. From the point that a urethane bond and an epoxy group can be efficiently introduced into one molecule, a urethane bond-containing compound (X) having an isocyanate group obtained by reacting a polyhydroxy compound and a polyisocyanate compound, and hydroxy A resin obtained by reacting the group-containing epoxy compound (Y) is preferable.

  Examples of the polyhydroxy compound used in producing the urethane-modified epoxy resin include polyether polyols such as polypropylene glycol, polyester polyols, adducts of hydroxycarboxylic acid and alkylene oxide, polybutadiene polyols, and polyolefin polyols. It is done. Of these, when a polyether polyol is used, a cured product having excellent adhesion and flexibility is obtained, which is preferable.

  The molecular weight of the polyhydroxy compound is preferably 300 or more and 5000 or less, and more preferably 500 or more and 2000 or less as a mass average molecular weight, from the viewpoint of excellent balance between flexibility and curability.

  The polyisocyanate compound used when producing the urethane-modified epoxy resin is not particularly limited as long as it is a compound having two or more isocyanate groups. Examples thereof include aliphatic polymer isocyanates, aromatic polyisocyanates, and polyisocyanate groups having aromatic hydrocarbon groups. Of these, aromatic polyisocyanates are preferred. Examples of the aromatic polyisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate.

  By the above reaction, a urethane prepolymer containing a free isocyanate group at the terminal is obtained. This is reacted with an epoxy resin having at least one hydroxyl group in one molecule (for example, diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of aliphatic polyhydric alcohol, and glycidol). A modified epoxy resin is obtained.

  The amount of the urethane-modified epoxy resin is preferably 0% by mass to 100% by mass in the epoxy resin, more preferably 0% by mass to 50% by mass, and more preferably 1% by mass to 50% by mass. More preferably, it is 2 mass% or more and 50 mass% or less, More preferably, it is 5 mass% or more and 30 mass% or less. This is because the balance between imparting flexibility to the cured product and the viscosity of the uncured product is improved.

  The urethane-modified epoxy resin is not particularly limited for its production. For example, it can be produced by reacting urethane and epoxy in a large amount of epoxy (for example, epoxy resin). The epoxy used when producing the urethane-modified epoxy resin is not particularly limited. For example, a conventionally well-known thing is mentioned. In addition, in this invention, the addition amount of a urethane-modified epoxy resin shall be the addition amount in the urethane-modified epoxy resin containing the excess epoxy resin used at the time of manufacture.

<Latent curing agent>
Next, the latent curing agent will be described. Although the latent curing agent does not function as a curing agent in a sealed state, that is, in a moisture blocking state, it is a hydrolytic latent curing agent that functions as a curing agent by opening the sealed state and hydrolyzing under the presence of moisture. , Does not function as a curing agent at room temperature, but melts, dissolves or activates when a certain amount of heat is applied, heat latent curing agent that functions as a curing agent, or generates a cation by light irradiation to react epoxy groups And a photocuring initiator for initiating. Examples of the hydrolytic latent curing agent include ketimine compounds. Examples of the heat latent curing agent include dicyandiamide, imidazoles, hydrazines, epoxy adducts of amines, acid anhydrides, liquid phenols, aromatic amines and the like. Examples of the UV curing initiator include aromatic diazonium salts, sulfonium salts, iodonium salts and the like. In the latent curing agent, two or more of these may be used in combination.

  The ketimine compound is not particularly limited as long as it is a compound having a ketimine bond (N = C), and examples thereof include a ketimine compound obtained by reacting a ketone with an amine.

  Examples of the ketone include methyl ethyl ketone, methyl isopropyl ketone, methyl tertiary butyl ketone, methyl cyclohexyl ketone, diethyl ketone, ethyl propyl ketone, ethyl butyl ketone, dipropyl ketone, dibutyl ketone, and diisobutyl ketone.

  The amine is not particularly limited. For example, aromatic polyamines such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldiphenylmethane: ethylenediamine, propylenediamine , Butylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, trimethylhexamethylenediamine, 1,2-propanediamine, iminobispropylamine, methyliminobispropylamine, DuPont Japan Products such as MPMD aliphatic polyamines: N-aminoethylpiperazine, 3-butoxyisopropylamine, etc. have an ether bond in the main chain Polyamine skeletons typified by monoamines and Sun Techno Chemical's product Jeffamine EDR148: isophoronediamine, 1,3-bisaminomethylcyclohexane, 1-cyclohexylamino-3-aminopropane, 3-aminomethyl-3,3 , 5-trimethylcyclohexylamine and other alicyclic polyamines: norbornane skeleton diamines represented by Mitsui Chemicals, Inc. NBDA: polyamide amines having amino groups at the molecular ends of the polyamide: 2,5-dimethyl-2,5-hexamethylene Products such as Jeffamine D230 and Jeffamine D400 manufactured by Sun Techno Chemical Co., Ltd. having a skeleton of diamine, mensendiamine, 1,4-bis (2-amino-2-methylpropyl) piperazine, polypropylene glycol (PPG) It is mentioned as examples.

  Examples of the imidazoles include imidazole compounds such as 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole. Etc. An addition reaction product (epoxy adduct) between these and an epoxy compound is used as the thermal latent curing agent.

  Examples of the hydrazines include adipic acid dihydrazide and isophthalic acid dihydrazide. As the thermal latent curing agent, an addition reaction compound (epoxy adduct) between these and an epoxy compound is used.

  Examples of the amines include 2-dimethylaminoethylamine and 3-dimethylamino-N-propylamine. An addition reaction product (epoxy adduct) of these and an epoxy compound is used as a thermal latent curing agent.

  Examples of the acid anhydride include trimellitic acid anhydride, pyromellitic acid anhydride, hexahydrophthalic acid anhydride, methylhexahydrophthalic acid anhydride, nadic acid anhydride, methyl nadic acid anhydride, tetrahydrophthalic acid anhydride. Products, methyltetrahydrophthalic anhydride, dodecenyl succinic anhydride (DSA) and the like.

  Examples of the liquid phenol include diallyl bisphenol A, diallyl bisphenol F, allylated phenol novolac resin, allylated dihydronaphthalene, diallyl resorcin and the like.

  Examples of the aromatic amines include m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldiphenylmethane, monomethyldiethyl-m-phenylenediamine, and the like.

  In the UV curing initiator, examples of the aromatic diazonium salt include p-methoxybenzenediazonium hexafluorophosphate. Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate. Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate. As other UV curing initiators, aromatic iodosyl salts, aromatic sulfoxonium salts, metallocene compounds, and the like can also be used.

  In actuality, amine adducts such as Ajinomoto Fine-Techno Amicure series that are commercially available as latent curing agents can be used, but those having a curing temperature of 100 ° C. or lower are preferably used. .

  Further, the content of the latent curing agent in the adhesive of the present invention is not particularly limited, and the optimum amount varies depending on the type of the curing agent. For example, the optimal amount for each curing agent known in the art can be preferably used. This optimum amount is described, for example, in Chapter 3 of “Review Epoxy Resin Basics” (Epoxy Resin Technical Association, published in 2003).

<Conductive agent>
Next, the conductive agent will be described. The conductive agent contained in the adhesive of the present invention imparts conductivity to the adhesive of the present invention. The conductive agent contained in the adhesive of the present invention contains at least an alginate. Examples of alginates include sodium, potassium and calcium salts of alginic acid. In particular, sodium alginate, which is a sodium salt, is preferably used as the alginate.

  The alginate is contained in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of the epoxy resin. The alginate is preferably contained in an amount of 1 part by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the epoxy resin. This is because if the alginate content is less than 0.1 parts by mass, sufficient electrodeposition coating properties cannot be obtained. If the alginate content exceeds 30 parts by mass, the strength of the structural adhesive decreases. Because.

  Moreover, the electrically conductive agent which the adhesive agent of this invention contains is not specifically limited except alginate, A conventionally well-known electrically conductive agent can be used, However, A metal type filler and a carbon type filler are mentioned suitably. Examples of the metal filler include metal powders such as Ag powder, Ni powder, Cu powder, and Ag-plated Cu powder; metal fibers such as brass fiber, Al fiber, Cu fiber, and stainless steel fiber; and metal flakes. Examples of the carbon filler include carbon black such as furnace black, acetylene black, and thermal black; graphite; and carbon fiber. Among these, carbon black is preferable.

  Examples of carbon black include ketjen black, which is the most common conductive carbon black, and high structure carbon black having an oil absorption of 0.5 mL / g or more. As carbon black, it is preferable to use ketjen black and carbon black having a high structure with an oil absorption of 0.5 mL / g or more in combination.

  A commercial item can be used as ketjen black. For example, Ketjen Black EC, Ketjen Black EC-600, and Ketjen Black EC-600JD manufactured by Lion Aguso are preferred. Examples of the high structure carbon black having an oil absorption amount of 0.5 mL / g or more include general SAF, HAF, GPF, FEF and the like.

  When carbon black is used as the conductive agent, the carbon black is preferably 1 part by mass or more and 20 parts by mass or less, more preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the epoxy resin. More preferably, the content is from 13 parts by mass to 13 parts by mass. This is because if the carbon black content is less than 1 part by mass, the conductivity will be reduced, and if the carbon black content exceeds 20 parts by mass, the viscosity and specific gravity will increase.

  By containing at least alginate as a conductive agent, the amount of conductive agent other than alginate, such as carbon black, blended as a conductive agent can be kept small, minimizing deterioration in physical properties as an adhesive. In addition, it is possible to impart conductivity without increasing the viscosity and specific gravity, and to apply an electrodeposition coating to the cured surface.

  In addition to the above epoxy resin, latent curing agent, and conductive agent containing at least an alginate, the adhesive of the present invention contains various additives as necessary, as long as the object of the present invention is not impaired. Can be contained. Examples of the additives include fillers, reaction retarders, anti-aging agents, antioxidants, pigments, dyes, plasticizers, silane coupling agents, thixotropic agents, adhesion-imparting agents, flame retardants, and antistatic agents. UV absorbers, surfactants, dispersants, dehydrating agents, solvents and the like. Two or more of these may be contained.

  Examples of the filler include organic or inorganic materials having various shapes. For example, calcium carbonate, wax stone clay, kaolin clay, calcined clay; silica sand, fumed silica, calcined silica, precipitated silica, ground silica, fused silica; diatomaceous earth; iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide Magnesium carbonate, zinc carbonate; carbon black; these fatty acids, resin acids, fatty acid ester treated products, and fatty acid ester urethane compound treated products.

  Examples of the reaction retarder include alcohol compounds. Examples of the anti-aging agent include hindered phenol compounds and hindered amine compounds. Examples of the antioxidant include butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA).

  The pigment may be either an inorganic pigment or an organic pigment. As pigments, for example, inorganic pigments such as titanium oxide, zinc oxide, ultramarine, bengara, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, sulfate; azo pigments, phthalocyanine pigments, quinacridone pigments, quinacridone quinone pigments, Dioxazine pigment, anthrapyrimidine pigment, anthanthrone pigment, indanthrone pigment, flavanthrone pigment, perylene pigment, perinone pigment, diketopyrrolopyrrole pigment, quinonaphthalone pigment, anthraquinone pigment, thioindigo pigment, benzimidazolone pigment, isoindoline pigment, Examples thereof include organic pigments such as carbon black.

  The dye is not particularly limited, and conventionally known dyes can be used. For example, black dye, yellow dye, red dye, blue dye, and brown dye can be mentioned.

  Examples of the plasticizer include polypropylene glycol, diisononyl phthalate (DINP), dioctyl phthalate (DOP), dibutyl phthalate (DBP); dioctyl adipate, isodecyl succinate; diethylene glycol dibenzoate, pentaerythritol ester; butyl oleate And methyl acetylricinoleate; tricresyl phosphate, trioctyl phosphate; propylene glycol adipate polyester, butylene glycol adipate polyester; alkylsulfonic acid phenyl ester (for example, mezamol manufactured by Bayer) and the like. These may be used alone or in combination of two or more.

  As the silane coupling agent, for example, trimethoxyvinylsilane and γ-glycidoxypropyltrimethoxysilane are particularly preferable because they are excellent in the effect of improving the adhesion to a wet surface and are general-purpose compounds.

  Examples of the thixotropic agent include Aerosil (manufactured by Nippon Aerosil Co., Ltd.) and Disparon (manufactured by Enomoto Kasei Co., Ltd.). Examples of the adhesion imparting agent include terpene resins, phenol resins, terpene-phenol resins, rosin resins, xylene resins, and the like.

  Examples of the flame retardant include chloroalkyl phosphate, dimethyl / methylphosphonate, bromine / phosphorus compound, ammonium polyphosphate, neopentyl bromide-polyether, brominated polyether, and the like.

  Examples of the antistatic agent generally include quaternary ammonium salts; hydrophilic compounds such as polyglycols and ethylene oxide derivatives.

  Examples of the ultraviolet absorber include 2-hydroxybenzophenone, benzotriazole, and salicylic acid ester.

  Examples of the surfactant (leveling agent) include polybutyl acrylate, pordimethylsiloxane, a modified silicone compound, and a fluorine-based surfactant. An example of the dispersant is Kyoeisha Chemical Co., Ltd. Floren G700. Examples of the dehydrating agent include vinyl silane.

  The manufacturing method of the adhesive of this invention is not specifically limited, It can manufacture by a conventionally well-known method. For example, the epoxy resin composition used in the adhesive of the present invention comprises an epoxy resin, a latent curing agent, a conductive agent containing at least an alginate, and various additives used as necessary under a reduced pressure, such as a mixer, etc. Can be obtained with sufficient stirring. Since the adhesive of the present invention is obtained by curing a thermosetting epoxy resin composition, the adhesive of the present invention can be obtained by heating the epoxy resin composition obtained as described above. Can do.

  As described above, the adhesive of the present invention is mainly composed of an epoxy resin and a latent curing agent, includes at least an alginate as a conductive agent, and the content of the alginate is 100 parts by mass of the epoxy resin. The structural adhesive is 0.1 parts by mass or more and 30 parts by mass or less. The adhesive of the present invention is obtained by curing a thermosetting epoxy resin composition, and when the epoxy resin composition obtained by mixing various components as described above is heated, By containing a predetermined amount of alginate in addition to the conductive agent, the blending amount of the conductive agent other than the alginate can be kept small. For this reason, the adhesive of this invention can suppress the fall of the physical property as an adhesive agent, and can provide electroconductivity and can apply electrodeposition coating to the surface after hardening, without raising a viscosity and specific gravity. Therefore, the adhesive of the present invention has electrodeposition coating properties, maintains adhesion to a member to be bonded such as a substrate and is excellent in corrosion resistance, and therefore can be suitably used as a structural adhesive.

  In addition, the “structural adhesive” is a highly reliable adhesive (JIS K6800) with little deterioration in adhesive properties even when a large load is applied for a long time. The adhesive of the present invention is used as a structural adhesive. Since it can be preferably used, it can be used, for example, as an adhesive for structural members in the fields of automobiles, vehicles (bullet trains, trains), civil engineering, architecture, electronics, aircraft, and the space industry.

  In addition to the structural adhesive, the adhesive of the present invention can also be used as an adhesive for general office work, medical use, and electronic materials. As adhesives for electronic materials, interlayer adhesives for multilayer substrates such as build-up substrates, die bonding agents, semiconductor adhesives such as underfills, BGA reinforcing underfills, anisotropic conductive films (ACF), Examples thereof include an adhesive for mounting such as anisotropic conductive paste (ACP).

  In addition to being used as an adhesive, the adhesive of the present invention can also be used for articles for general use in which a thermosetting resin such as an epoxy resin is used. For example, paints, coating agents, molding materials (including sheets, films, FRP, etc.), insulating materials (including printed circuit boards, electric wire coatings, etc.), sealants and the like can be mentioned. Sealing agents include capacitors, transistors, diodes, light emitting diodes, potting and dipping for IC and LSI, transfer mold sealing, potting sealing for IC and LSI COB, COF, TAB, flip chip, etc. Underfill, and sealing (including reinforcing underfill) when mounting IC packages such as QFP, BGA, and CSP.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
<Examples 1 to 7 and Comparative Examples 1 to 4>
Each component shown in “Table 1” was blended in the addition amount (part by mass) shown in the same table, and these were uniformly mixed to prepare each composition shown in “Table 1”. The addition amount (parts by mass) of each component in each Example and Comparative Example is as shown in “Table 1”.

Each component shown in the above "Table 1" is as follows. Moreover, bisphenol A type epoxy resin, urethane modified epoxy resin and rubber modified epoxy resin were used as the epoxy resin.
Bisphenol A type epoxy resin: EP-834, manufactured by Japan Epoxy Resin Co., Ltd. Urethane-modified epoxy resin: EPU-78-11, manufactured by ADEKA Co., Ltd. Rubber-modified epoxy resin: EPR-1309, manufactured by ADEKA Co., Ltd. Multilayer structured organic fine particles: IM-601, manufactured by Ganz Kasei Co., Ltd., latent curing agent: DICY-15, manufactured by Japan Epoxy Resin Co., Ltd., carbon black: MA600, manufactured by Mitsubishi Chemical Co., Ltd., sodium alginate, sodium alginate, manufactured by Wako Pure Chemical Industries, Ltd., iron powder: JFE, silica: AEROSIL RY 200S, Nippon Aerosil, catalyst: DUMU99, Hodogaya Chemical, adhesion promoter: KBM-403, Shin-Etsu Chemical

<Evaluation>
About each obtained composition, the electrodeposition coating, the viscosity, specific gravity, and intensity | strength were evaluated as follows by the method shown below. Each measurement result is shown in “Table 1”.

(Electrodeposition coating)
Electrodeposition coating was performed on the test pieces coated with the obtained compositions, and the adhesion was evaluated. The conditions for electrodeposition coating are as follows. After the electrodeposition coating, the thickness of the formed electrodeposition coating was measured. Table 1 shows the measurement results. In Table 1, o and x indicate the following states, respectively.
・ Conditions for electrodeposition coating Paint: Saxade S30S Gray Voltage: 200V
Energizing time: 180s
Distance between electrodes: 150mm
Baking: 170 ° C x 20min
-Electrodeposition coating state ○: Electrodeposition coating is applied ×: Electrodeposition coating is not applied

(viscosity)
The viscosity of each composition obtained by uniformly kneading as described above was measured. Specifically, for each of the obtained compositions, the viscosity at 40 ° C. was measured at 3 rpm using a BS viscometer and No. 7 rotor. Evaluation is performed as follows, and the measurement results are shown in “Table 1”.
○: Less than 700 Pa · s / 40 ° C ×: More than 700 Pa · s / 40 ° C

(specific gravity)
Moreover, the specific gravity of each obtained composition was measured using the underwater substitution method. The specific gravity is preferably 1.2 or less. Table 1 shows the measurement results.

(Strength)
Further, the shear strength (MPa) and peel strength (N) of each composition obtained were measured. The shear strength is preferably 15 MPa or more, and the peel strength is preferably 100 N or more. Regarding the shear strength, the shear strength was measured at a tensile speed of 5 mm / min according to JIS K6850-1999. As the adherend, two mild steel plates (25 × 100 × 0.8 mm) were used, and the length of the joint was 10 mm. Each composition was heated from room temperature to 230 ° C. and then kept at 230 ° C. for 1 hour to be cured. The thickness of the adhesive after bonding was 0.1 mm. Table 1 shows the measurement results. The peel strength was measured by performing a 90 ° peel test in accordance with JIS K 6256. Table 1 shows the measurement results.

  In each of Examples 1 to 7 containing carbon black and alginate as a conductive agent, electrodeposition coating was applied to the surface of the adhesive, and the thickness of the electrodeposition coating could be 1.0 mm or more. In addition, in Examples 1 to 7, the viscosity could be kept high. In each of Examples 1 to 7, the shear strength was 15 MPa or more, and the peel strength was 100 N or more.

  On the other hand, in Comparative Example 1 which did not contain any carbon black, Na alginate or iron powder as a conductive agent, electrodeposition coating could not be applied and the specific gravity was as high as 1.2. In Comparative Examples 2 and 3 containing carbon black as a conductive agent, electrodeposition coating could be applied, but when the amount of carbon black was small as in Comparative Example 2, the electrodeposition coating was 0.1 mm. It could only be applied. Moreover, when there was much compounding quantity of carbon black like the comparative example 3, although the electrodeposition coating could be applied 1.0 mm or more, the viscosity became low. In Comparative Example 4 containing iron powder as a conductive agent, electrodeposition coating could be applied to 1.0 mm or more, and the viscosity could be maintained high, but the specific gravity was high and the shear strength was low. The peel strength was also lowered.

  Therefore, as in Examples 1 to 7, by containing a predetermined amount of carbon black and alginate as a conductive agent, the strength of the adhesive is kept high, the physical properties are kept good, and the viscosity and specific gravity are increased without increasing. Since electrodeposition coating can be applied to the subsequent surface, an electrodeposition coating property is provided, and a highly reliable structural adhesive having excellent corrosion resistance while maintaining adhesion to an adherend such as a substrate is obtained. be able to.

  As described above, the structural adhesive according to the present invention has an electrodeposition coating property, maintains adhesion to a member to be bonded such as a substrate and is excellent in corrosion resistance, and therefore adheres to a structural member such as an automobile or a vehicle. Suitable for use as an agent.

Claims (3)

The main component is an epoxy resin and a latent curing agent, and at least an alginate is included as a conductive agent.
Content of the said alginate is 0.1 to 30 mass parts with respect to 100 mass parts of said epoxy resins, The structural adhesive agent characterized by the above-mentioned. As the conductive agent, further containing carbon black,
The structural adhesive according to claim 1, wherein the carbon black is contained in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the epoxy resin.   The structural adhesive according to claim 1 or 2, wherein the alginate is a sodium salt.