JP2014031498A - Heat conductive adhesive for metallic heat transfer tube and metallic heat transfer tube coated with the heat conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discover a heat conductive adhesive for a metallic heat transfer tube excellent in blocking resistance and curability at manufacturing, adhesive property and thermal conductivity, and to provide a metallic heat transfer tube for a heat exchanger excellent in these properties.SOLUTION: A heat conductive adhesive for a metallic heat transfer tube contains an acryl modified epoxy resin having a weight average molecular weight of 20,000 to 400,000 (A), a polyhydroxypolyether resin (an acryl modified epoxy resin is excluded) (B), at least one kind of crosslinking agent selected from the group consisting of a melamine resin, a block polyisocyanate compound and a resol type phenol resin (C) and a heat-conductive filler (D), and 1 to 60 pts.mass of the heat-conductive filler (D) based on total 100 pts.mass of a solid content of the acryl modified epoxy resin (A), the polyhydroxypolyether resin (B) and the crosslinking agent (C).

Description

  The present invention relates to a heat conductive adhesive for a metal heat transfer tube, and more specifically, a heat conductive adhesive for a metal heat transfer tube excellent in blocking resistance and film adhesion at the time of manufacture, and the metal heat transfer adhesive. It is related with the metal heat exchanger tube for heat exchangers which applied the heat conductive adhesive for heat tubes.

  A multi-tube type, double-pipe type, spiral type, etc., in which a heat exchange fin group (core part) combined with a large number of heat transfer pipes and a heat medium introduction / extraction part (distribution / collection tank part) are integrally formed The heat exchanger (see FIG. 1) is often formed of aluminum, particularly an aluminum alloy, from the viewpoint of heat transfer, lightness, and the like.

  Conventionally, when manufacturing an aluminum heat exchanger, a material in which a material having a low melting point (brazing material) with respect to the core material is clad on both sides or one side of the aluminum material as the core material is used. After forming and assembling each member by using it for some or all of the components, and then assembling them, the components are heated to a temperature above which the brazing material melts in the furnace, and the components are joined together by the brazing material Thus, a heat exchange passage group (core part) of the heat exchanger is manufactured.

  However, when manufacturing an aluminum heat exchanger with a brazing material as described above, since the melting temperature of the brazing material is usually about 600 ° C., the aluminum heat exchanger is brought to the brazing temperature above that temperature. There is a problem that the energy consumed by the brazing equipment is large at the time of brazing, and bonding with an adhesive is considered preferable from the viewpoint of cost and simplicity.

  For example, a polyurethane-based thermosetting composition mainly containing an active methylene-based block polyisocyanate as a metal adhesive is disclosed (Patent Document 1).

  Moreover, it is a precoat metal plate used for interiors, home appliances, etc., and an “adhesive precoat metal plate” bonded via an adhesive is disclosed (Patent Document 2). Moreover, in the manufacturing process of a heat exchanger, it is disclosed to commercialize a precoated metal plate that is applied with an adhesive and heat-cured when the components are assembled (Patent Document 3). However, these adhesives have all the blocking resistance (the part where the adhesive is applied to the heat transfer tube is not fixed), thermal conductivity, and adhesiveness when the heat transfer tube coated with the adhesive is left standing. It was not enough.

  From such a background, there has been a demand for a thermally conductive adhesive for metal heat transfer tubes that has good blocking resistance during production and is excellent in adhesion and thermal conductivity.

JP-A-9-255915 JP-A-8-267660 JP 2004-42247 A

  The object of the present invention is to find a heat conductive adhesive for metal heat transfer tubes excellent in blocking resistance at the time of production, curability after heat curing, adhesion and thermal conductivity, and heat for the metal heat transfer tubes It is providing the metal heat exchanger tube for heat exchangers which apply | coated the conductive adhesive.

  As a result of intensive studies to solve the above problems, the present inventors have found that an acrylic-modified epoxy resin (A), a polyhydroxy polyether resin (excluding an acrylic-modified epoxy resin) (B), a melamine resin, a block Thermally conductive adhesive for metal heat transfer tubes containing at least one crosslinking agent (C) selected from the group consisting of a polyisocyanate compound and a resol type phenolic resin and a thermally conductive filler (D) with a certain blending ratio Thus, the inventors have found that the above-mentioned problems can be solved, and have completed the present invention.

That is, the present invention
1. Acrylic modified epoxy resin (A) having a weight average molecular weight of 20,000 to 400,000, a polyhydroxy polyether resin having a weight average molecular weight of 800 to 20,000 (excluding an acrylic modified epoxy resin) (B), A heat conductive adhesive containing at least one crosslinking agent (C) selected from the group consisting of a melamine resin, a block polyisocyanate compound and a resol type phenol resin, and a heat conductive filler (D),
1-60 mass parts of heat conductive filler (D) is contained with respect to 100 mass parts of total amounts of solid content of acrylic modified epoxy resin (A), polyhydroxy polyether resin (B), and crosslinking agent (C). Thermally conductive adhesive for metal heat transfer tubes.

  2. The heat for a metal heat transfer tube according to claim 1, wherein the thermally conductive filler (D) is at least one selected from the group consisting of flaky aluminum, flaky nickel, flaky carbon, boron nitride, and diamond powder. Conductive adhesive.

  3. The heat conductive adhesive for metal heat transfer tubes according to Item 1 or 2, wherein the polyhydroxy polyether resin (B) contains a polymer (b1) obtained by polycondensation of a phenol compound and epihalohydrin.

  4). A monovalent amine compound having reactivity with an epoxy group in the polymer (b1), a polymer (b1) obtained by polycondensation of a phenol compound and an epihalohydrin with a polyhydroxy polyether resin (B), and The heat for a metal heat transfer tube according to any one of 1 to 3, comprising a polymer (b12) obtained by reacting at least one (b2) selected from the group consisting of monovalent acid compounds. Conductive adhesive.

  It is related with the metal heat exchanger tube for heat exchangers which apply | coats the heat conductive adhesive for metal heat exchanger tubes of any one of 5.1-4.

  The heat conductive adhesive for metal heat transfer tubes of the present invention is excellent in storage stability, blocking resistance during production, curability, adhesiveness, and heat conductivity. Moreover, the metal heat exchanger tube for heat exchangers using the heat conductive adhesive for the metal heat exchanger tube has good adhesion to metal. That is, each member which comprises a heat exchanger is joined firmly by the adhesive agent of this invention apply | coated to the heat exchanger tube.

  A heat exchanger assembled with a flat multi-hole tube for heat exchangers using a heat conductive adhesive can use hydrophilic processing fins, so it is expected to improve performance compared to brazed products that can only use bare fins in terms of evaporation performance. Is done. In addition, the spiral grooved tube that fixes the tube and the fin by expanding the tube is expected to improve the heat exchanger performance by about 10% by using an adhesive together.

It is an example of a multi-tube heat exchanger. It is an example of the flowchart which shows the manufacturing method of the metal heat exchanger tubes for heat exchangers. It is a figure which shows a flat multi-hole heat exchanger tube as an example of the metal heat exchanger tube for heat exchangers.

  The heat conductive adhesive for metal heat transfer tubes of the present invention includes acrylic modified epoxy resin (A), polyhydroxy polyether resin (excluding acrylic modified epoxy resin) (B), melamine resin, block polyisocyanate compound And a heat conductive adhesive for a metal heat transfer tube containing at least one cross-linking agent (C) selected from the group consisting of a resol type phenol resin and a heat conductive filler (D). Hereinafter, the present invention will be described in detail.

[Heat conductive adhesive for metal heat transfer tubes]
Acrylic modified epoxy resin (A)
The acrylic-modified epoxy resin (A) can be synthesized by a modification method such as an esterification method, a modified esterification method (direct polymerization method), or a graft method. The esterification method is a carboxyl obtained by copolymerizing a monomer having both a carboxyl group such as (meth) acrylic acid and a radically polymerizable unsaturated double bond and another monomer having a radically polymerizable unsaturated double bond. A part of the carboxyl group in the acrylic copolymer having a group and a part of the epoxy group in the bisphenol type epoxy resin are heated in the presence of an esterification catalyst, for example, in an organic solvent to cause an ester reaction. In this method, the epoxy resin is modified.

  The modified esterification method (direct polymerization method) is a carboxyl in a monomer having both a carboxyl group such as (meth) acrylic acid and a radically polymerizable unsaturated double bond in part of an epoxy group in a bisphenol type epoxy resin. Reacting with a group, introducing a polymerizable unsaturated double bond into the resin, and then copolymerizing this resin with another monomer having a radically polymerizable unsaturated double bond, for example, in an organic solvent. In this method, the epoxy resin is modified.

  The graft method is a monomer having both a carboxyl group such as (meth) acrylic acid and a radical polymerizable unsaturated double bond using a free radical generator such as benzoyl peroxide in the presence of a bisphenol type epoxy resin, This is a method of modifying an epoxy resin by grafting an acrylic copolymer onto a bisphenol type epoxy resin by copolymerizing a mixture of other monomers having a radical polymerizable unsaturated double bond, for example, in an organic solvent. .

  As a bisphenol type epoxy resin used as a raw material for the acrylic-modified epoxy resin (A), for example, a resin obtained by condensing epichlorohydrin and bisphenol in the presence of a catalyst such as an alkali catalyst as necessary to increase the molecular weight. , A resin obtained by condensing epichlorohydrin and bisphenol in the presence of a catalyst such as an alkali catalyst as necessary to obtain a low molecular weight epoxy resin, and polyaddition reaction of this low molecular weight epoxy resin and bisphenol, In addition, an epoxy ester resin obtained by reacting these obtained resins or the above low molecular weight epoxy resin with a dibasic acid can be used.

  The bisphenol type epoxy resin has a number average molecular weight of preferably 2,000 to 30,000, more preferably 3,000 to 20,000, and an epoxy equivalent of preferably 1,000 to 15,000 g / eq, more preferably Is preferably in the range of 1,500 to 10,000 g / eq from the viewpoints of curability, blocking resistance, adhesion and the like.

  In this specification, the number average molecular weight and the weight average molecular weight of the resin were measured according to JIS K 0124-83 and measured by GPC (gel permeation chromatograph) with reference to standard polystyrene.

  The measurement in the postscript manufacturing example etc. is as a GPC apparatus, "HLC8120GPC" (brand name, Tosoh Co., Ltd. product), As a column, "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL", Using “TSKgel G-2000HXL” (both manufactured by Tosoh Corporation, trade name), mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 ml / min, detector: conditions of RI refractometer It was done in.

  Moreover, in this specification, the glass transition temperature (Tg) of resin is based on a differential thermal analysis (DSC). The glass transition temperature (Tg) is a value measured by DSC (Differential Scanning Calorimeter) based on JISK7121 (Plastic transition temperature measurement method) at a heating rate of 10 ° C./min. The measurement in the following production examples, etc., was performed by using “SSC5200” (trade name, manufactured by Seiko Denshi Kogyo Co., Ltd.) as a DSC, weighing a predetermined amount in a sample dish, and drying at 130 ° C. for 3 hours. I did it.

  Examples of the bisphenol include bis (4-hydroxyphenyl) methane [bisphenol F], 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2,2-bis (4-hydroxyphenyl) butane [bisphenol B], bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, Examples thereof include p- (4-hydroxyphenyl) phenol, oxybis (4-hydroxyphenyl), sulfonylbis (4-hydroxyphenyl), 4,4′-dihydroxybenzophenone, bis (2-hydroxynaphthyl) methane, and the like. Of these, bisphenol F and bisphenol A can be preferably used. The said bisphenol compound can be used individually by 1 type or in combination of 2 or more types.

As a dibasic acid used for manufacture of the epoxy ester resin, the following formula (1)
_{HOOC- (CH 2) n -COOH ···} (1)
(In Formula (1), n is an integer of 1-12.)
The compound shown by can be used suitably. Specific examples include succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexahydrophthalic acid and the like.

  Commercially available products suitable as the bisphenol A type epoxy resin include, for example, jER828EL (epoxy equivalent of about 187, number average molecular weight of about 350), jER1002 (epoxy equivalent of about 650, number average molecular weight of about 1, manufactured by Mitsubishi Chemical Corporation). 200), jER1004 (epoxy equivalent of about 915, number average molecular weight of about 1,650), jER1007 (epoxy equivalent of about 1,700, number average molecular weight of about 2,900), jER1009 (epoxy equivalent of about 3,500, number average molecular weight of about 3,750), jER1010 (epoxy equivalent of about 4,500, number average molecular weight of about 5,500); Araldite AER6099 (epoxy equivalent of about 3,500, number average molecular weight of about 3,800) manufactured by Asahi Kasei Epoxy Corporation; And Epomic R-309 (epoxy equivalent of about 3,500, several flats, manufactured by Mitsui Chemicals, Inc.) Average molecular weight of about 3,800).

  As the bisphenol A type epoxy resin, for example, the above-mentioned commercially available bisphenol A type epoxy resin or bisphenol A type epoxy resin obtained by reacting bisphenol A with a low molecular weight epoxy compound can be used.

  Commercially available products of bisphenol F type epoxy resin include, for example, jER806 (epoxy equivalent of about 170, number average molecular weight of about 320), jER4007P (epoxy equivalent of about 2,300, number average molecular weight of about 3, manufactured by Mitsubishi Chemical Corporation). 300), jER4010P (epoxy equivalent of about 4,400, number average molecular weight of about 5,500), and the like.

  As the bisphenol F type epoxy resin, for example, the above-mentioned commercially available bisphenol F type epoxy resin, bisphenol F type epoxy resin obtained by reacting bisphenol F and a low molecular weight epoxy compound to increase the molecular weight can be used.

  Further, as the epoxy resin component of the acrylic resin epoxy resin (A), a compound obtained by reacting a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin with bisphenol A and / or bisphenol F is also epoxy. It can be used as a resin.

  In the acrylic-modified epoxy resin (A), particularly from the viewpoint of adhesion, 15 masses of bisphenol F and / or bisphenol F-type epoxy resin are used as the epoxy resin, based on the total amount of bisphenol and bisphenol-type epoxy resin as raw material components An acrylic-modified epoxy resin (A) obtained by modifying an epoxy resin obtained by reacting raw material components containing at least% can be suitably used.

  In the epoxy resin component of the acrylic-modified epoxy resin (A), the amount of bisphenol F and / or bisphenol F type epoxy resin, which are essential components in the raw material components, is bisphenol and bisphenol type from the viewpoint of adhesion, blocking resistance, etc. It is 15 mass% or more based on the total amount of the epoxy resin, preferably 18 to 90 mass%, more preferably 20 to 80 mass%.

  Examples of the monomer having both a carboxyl group and a radical polymerizable unsaturated double bond used in the production of the acrylic-modified epoxy resin (A) include (meth) acrylic acid, maleic acid, crotonic acid, itaconic acid, and fumaric acid. Among them, methacrylic acid can be preferably used. These can be used alone or in combination of two or more. In the present specification, (meth) acrylic acid means acrylic acid or methacrylic acid.

  The other monomer having a radical polymerizable unsaturated double bond used in the acrylic modified epoxy resin (A) is a monomer copolymerizable with a monomer having both the carboxyl group and the radical polymerizable unsaturated double bond. Any aromatic vinyl monomer such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, chlorostyrene, or the like can be used. Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-, i- or t-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, Lauryl acrylate, cyclohexyl acrylate, methyl methacrylate Ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-, i- or t-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, methacrylic acid C1-C18 alkyl ester or cycloalkyl ester of acrylic acid or methacrylic acid such as cyclohexyl; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, C2-C of acrylic acid or methacrylic acid such as 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, hydroxybutyl methacrylate Hydroxyalkyl esters: N-substituted acrylamide monomers such as N-methylol acrylamide, N-butoxymethyl acrylamide, N-methoxymethyl acrylamide, N-methylol methacrylamide, N-butoxymethyl methacrylamide, etc., N-substituted methacrylamide monomers, etc. Or a mixture of two or more thereof. In the present invention, the other monomer having a radically polymerizable unsaturated double bond includes a combination of an aromatic vinyl monomer and an alkyl ester or cycloalkyl ester having 1 to 18 carbon atoms of acrylic acid or methacrylic acid. It is preferable.

  As the other polymerizable unsaturated monomer, a mixture of styrene and ethyl acrylate can be particularly preferably used, and the constituent mass ratio of styrene / ethyl acrylate is 99.9 / 0.1 to 40/60, Is preferably in the range of 99/1 to 50/50.

  In the esterification method, the acrylic copolymer having a carboxyl group is not particularly limited in the constitutional ratio and type of the monomer, but usually a monomer having both a carboxyl group and a radically polymerizable unsaturated double bond is used. , Based on the total amount of all monomers, preferably 15 to 80% by mass, particularly preferably 20 to 60% by mass, and other monomer having a radical polymerizable unsaturated double bond is 85 to 20% by mass, particularly 80 to 40% by mass. It is preferable that it is mass%.

  The acrylic copolymer having a carboxyl group can be easily prepared by, for example, subjecting the monomer composition to a solution polymerization reaction in an organic solvent in the presence of a polymerization initiator. The acrylic copolymer having a carboxyl group has an acid value of 100 to 500 mgKOH / g, particularly 100 to 400 mgKOH / g, and a weight average molecular weight of 7,500 to 150,000, particularly 10,000 to 100,000. Preferably there is.

  The esterification method can be carried out by a method known per se. For example, an esterification catalyst is blended in a uniform organic solvent solution of a bisphenol-type epoxy resin and an acrylic copolymer having a carboxyl group. The reaction can usually be performed at a reaction temperature of 60 to 130 ° C. for about 1 to 6 hours until all of the epoxy groups are consumed.

  Examples of the esterification catalyst include tertiary amine compounds such as triethylamine and dimethylethanolamine, and quaternary salt compounds such as triphenylphosphine. Of these, tertiary amine compounds are preferred. Can be used.

  The solid content concentration in the reaction between the bisphenol-type epoxy resin and the acrylic copolymer having a carboxyl group is not particularly limited as long as the reaction system is within a viscosity range that does not hinder the reaction. Moreover, when using an esterification catalyst at the time of carrying out ester addition reaction, the usage-amount is normally used in 0.1-1 equivalent with respect to 1 equivalent of epoxy groups in a bisphenol type epoxy resin. Good.

  The content ratio of the bisphenol-type epoxy resin and the acrylic copolymer having a carboxyl group is not particularly limited, but usually the bisphenol-type epoxy resin is 60 to 90% by mass, particularly 70 to 90% by mass. Preferably, the acrylic copolymer having a carboxyl group is 10 to 40% by mass, particularly 10 to 30% by mass.

  The grafting method can be carried out by a method known per se, for example, in an organic solvent solution of a bisphenol type epoxy resin heated to 80 to 150 ° C., a radical generator, a carboxyl group and a radical polymerizable unsaturated double. It can be carried out by gradually adding a uniform mixed solution of a monomer having a bond and a mixture of other monomers having a radically polymerizable unsaturated double bond and maintaining the same temperature for about 1 to 10 hours. Examples of the radical generator include azobisisobutyronitrile, benzoyl peroxide, t-butyl perbenzoyl octanoate, t-butyl peroxy-2-ethylhexanoate, and the like.

  In the grafting method, the use ratio of the epoxy resin component and the polymerizable unsaturated monomer component containing the carboxyl group-containing polymerizable unsaturated monomer is not particularly limited, but usually the former: latter ratio is 95. -70 mass%: It is suitable for it to exist in the range of 5-30 mass%. In this case, the carboxyl group-containing polymerizable unsaturated monomer is preferably blended so as to be 20 to 80% by mass in the total polymerizable unsaturated monomer. The amount of the radical generator used in the graft polymerization reaction is usually preferably in the range of 3 to 15% by mass with respect to the total amount of the polymerizable unsaturated monomer components containing the carboxyl group-containing polymerizable unsaturated monomer. is there.

  In the esterification method (modified esterification method), the carboxyl group in the acrylic resin undergoes an ester addition reaction with the epoxy group in the epoxy resin component during the ester addition reaction, so an epoxy group is required in the epoxy resin component. The average number of epoxy groups per molecule of epoxy resin is 0.5 to 2, preferably 0.5 to 1.6. On the other hand, in the grafting method, the grafting reaction takes place by hydrogen abstraction of the epoxy resin main chain and the graft polymerization reaction proceeds, so that the epoxy group does not have to exist substantially in the epoxy resin.

  As an organic solvent for preparing the acrylic-modified epoxy resin (A), a bisphenol type epoxy resin and an acrylic copolymer having a carboxyl group or a monomer having both a carboxyl group and a radically polymerizable unsaturated double bond and radical polymerization Organic solvent that dissolves a mixture of other monomers having a polyunsaturated unsaturated bond, and does not hinder the formation of an emulsion when neutralizing and making aqueous the acrylic-modified epoxy resin that is a reaction product thereof As long as these are known, those known per se can be used.

  As the organic solvent, alcohol solvents, cellosolve solvents and carbitol solvents are preferable. Specific examples of the organic solvent include isopropanol, butyl alcohol, 2-hydroxy-4-methylpentane, 2-ethylhexyl alcohol, cyclohexanol, ethylene glycol, diethylene glycol, 1,3-butylene glycol, ethylene glycol monoethyl ether, ethylene Examples include glycol monobutyl ether and diethylene glycol monomethyl ether.

  As the organic solvent, organic solvents that are difficult to mix with water other than those described above can be used as long as they do not hinder the stability of the acrylic-modified epoxy resin (A) in the aqueous medium. Examples of the solvent include aromatic hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, ketone solvents such as acetone and methyl ethyl ketone, and the like.

  The acrylic-modified epoxy resin (A) has a carboxyl group, and has an acid value in the range of 10 to 160 mgKOH / g, particularly 20 to 100 mgKOH / g, from the viewpoint of water dispersibility and storage stability. Is preferred.

  The acrylic-modified epoxy resin (A) has a weight average molecular weight of 20,000 to 400,000, preferably 25,000 to 300,000, more preferably 30,000 to 200, from the viewpoint of curability and blocking resistance. Within the range of 1,000.

  The acrylic-modified epoxy resin (A) has a glass transition temperature (Tg) in the range of 50 to 160 ° C., particularly 60 to 150 ° C., more particularly 70 to 140 ° C., from the viewpoint of blocking resistance and coating workability. It is preferable that An acrylic modified epoxy resin (A) can be used individually or in combination of 2 or more types. The acrylic-modified epoxy resin (A) can be made dispersible in an aqueous medium by neutralizing at least a part of the carboxyl groups in the resin with a basic compound.

  As the basic compound used for neutralizing the carboxyl group, an amine compound, ammonia and the like are preferably used. Representative examples of the amine compounds include alkylamine compounds such as trimethylamine, triethylamine, and tributylamine; alkanolamine compounds such as dimethylethanolamine, diethanolamine, and aminomethylpropanol; and cyclic amine compounds such as morpholine. The degree of neutralization of the acrylic-modified epoxy resin (A) is not particularly limited, but is usually in the range of 0.1 to 2.0 equivalent neutralization with respect to the carboxyl group in the acrylic-modified epoxy resin (A). Preferably there is.

  The aqueous medium may be only water, but may be a mixture of water and an organic solvent. As the organic solvent, any of those known per se can be used, and those listed as organic solvents that can be used in the preparation of the acrylic-modified epoxy resin (A) can be suitably used. The amount of the organic solvent in the heat conductive adhesive for metal heat transfer tubes of the present invention is 20% by mass with respect to the total amount of resin solids of the heat conductive adhesive for metal heat transfer tubes from the viewpoint of environmental protection. The following range is desirable.

  In order to neutralize and disperse the acrylic-modified epoxy resin (A) in an aqueous medium, a conventional method may be used. For example, the acrylic-modified epoxy resin (A) is acrylic-modified under stirring in an aqueous medium containing a basic compound as a neutralizing agent. A method of gradually adding the epoxy resin (A), neutralizing the acrylic-modified epoxy resin (A) with a basic compound, and then adding an aqueous medium to the neutralized product or stirring the neutralized product under stirring Can be carried out by, for example, a method of adding to the aqueous medium.

  The average particle size of the dispersion in which the acrylic-modified epoxy resin (A) is dispersed in an aqueous medium is preferably in the range of 50 to 1,000 nm, particularly 100 to 500 nm.

  In the present invention, the average particle diameter of the resin particles is a concentration suitable for measuring a sample with deionized water using a submicron particle analyzer N5 (trade name, manufactured by Beckman Coulter, Inc., particle size distribution measuring device). And measured at room temperature (20 ° C.).

Polyhydroxy polyether resin (B)
The polyhydroxy polyether resin (B) is not particularly limited as long as it is a polyhydroxy polyether resin having a specific molecular weight, and examples thereof include a thermoplastic resin having a bisphenol type epoxy resin skeleton. The polyhydroxy polyether resin (B) is usually produced from the same raw material as the raw material for producing the epoxy resin, and mainly contributes to the adhesion and blocking resistance of the adhesive. is there. In the adhesive of the present invention, the polyhydroxy polyether resin (B) refers to a polyhydroxy polyether resin other than an acrylic-modified epoxy resin.

  For example, when the polyhydroxy polyether resin (B) is synthesized by reacting bisphenol A and epichlorohydrin, the polyhydroxy polyether resin (B) has a structure having a repeating unit represented by the following structural formula as a basic skeleton. .

  The polyhydroxy polyether resin (B) contains many OH groups and —O— groups (ether groups) in the molecular chain. The OH group contributes to an increase in adhesion by forming a hydrogen bond with the base material, and the —O— group increases the flexibility of the resin by having a structure that allows easy rotational movement within the molecule. Contribute.

  The polyhydroxy polyether resin (B) can be synthesized, for example, by the following method (1) or method (2).

  Method (1): A method of polycondensing a phenol compound and epihalohydrin. As the phenol compound, a divalent phenol compound is usually used, and examples of the mononuclear divalent phenol include resorcin, hydroquinone, catechol and the like. Examples of the dinuclear dihydric phenol include bisphenol A and bisphenol F. These phenol compounds can be used alone or in combination of two or more. As epihalohydrin, epichlorohydrin or the like can be used. Above all, a polymer obtained by reacting bisphenol A and epichlorohydrin can be preferably used. In the polycondensation reaction, an acid or alkali catalyst can be used as necessary.

  Method (2): Reacting the epoxy group of the polymer (b1) obtained by polycondensation of a phenol compound and epihalohydrin with an excess of epihalohydrin with a compound (b2) having reactivity with the epoxy group. How to make. In Method 2, the polycondensation reaction between the phenol compound and epihalohydrin can be carried out in the same manner as in Method 1. In the method (2), since the polycondensation reaction between the phenol compound and the epihalohydrin is synthesized under the condition of excess of the epihalohydrin that is an epoxy compound, the resulting polycondensation reaction product has an epoxy group.

  The polycondensation reaction in the above method (1) and method (2) can be performed basically in the same manner as the epoxy resin in the acrylic-modified epoxy resin (A).

  Specifically, for example, epichlorohydrin and bisphenol can be condensed in the presence of a catalyst such as an alkali catalyst as required to cause a high molecular weight reaction.

  Alternatively, epichlorohydrin and bisphenol may be condensed in the presence of a catalyst such as an alkali catalyst as necessary to obtain a low molecular weight epoxy resin, and this low molecular weight epoxy resin and bisphenol are subjected to a polyaddition reaction. it can.

  As the polycondensation reaction product of the above method (2), the epoxy resin exemplified as the raw material of the acrylic-modified epoxy resin (A) can be used.

  Specifically, for example, a resin obtained by condensing epichlorohydrin and bisphenol in the presence of a catalyst such as an alkali catalyst to increase the molecular weight, if necessary, epichlorohydrin and bisphenol, if necessary, an alkali catalyst or the like In the presence of the catalyst, a resin obtained by condensation to give a low molecular weight epoxy resin and a polyaddition reaction of the low molecular weight epoxy resin and bisphenol can be exemplified.

  In the method (2), examples of the compound (b2) having reactivity with an epoxy group include a compound having reactivity with an epoxy group, specifically, a monovalent amine compound, a monovalent acid compound, phosphorus An acid compound etc. can be mentioned.

  Examples of monovalent amine compounds include primary monoamines such as methylamine, ethylamine, propylamine, monoethanolamine, and isopropanolamine; secondary monoamines such as diethylamine, diethanolamine, diisopropanolamine, and N-ethylethanolamine; triethylamine And tertiary monoamines such as

  As said monovalent | monohydric acid compound, a monobasic acid etc. can be mention | raise | lifted, for example. Examples of monobasic acids include fatty acids such as benzoic acid, formic acid, acetic acid, lactic acid, propionic acid, butyric acid, caproic acid, lauric acid, and stearic acid; and hydroxycarboxylic acids such as dimethylolpropionic acid and 12-hydroxystearic acid. I can give you.

  Examples of the phosphoric acid compound include metaphosphoric acid, orthophosphoric acid, phosphorous acid, and the like.

  The polyhydroxy polyether resin (B) has a weight average molecular weight of 800 to 20,000, preferably 1,000 to 15,000, more preferably 1,200 to 10,000 from the viewpoints of adhesion and blocking resistance. Is within the range.

  In addition, the polyhydroxy polyether resin (B) may be in the form of an emulsion with a surfactant or the like in order to facilitate aqueous formation. As the surfactant, a normal surfactant such as a nonionic surfactant or an anionic surfactant can be used. From the viewpoint of dispersion stability, a nonionic surfactant that is in the form of an emulsion can be suitably used.

  In the heat conductive adhesive for metal heat transfer tubes of the present invention, the ratio of acrylic modified epoxy resin (A) and polyhydroxy polyether resin (B) (acryl modified epoxy resin (A) / polyhydroxy polyether resin (B )) Is the solid content mass ratio of both, and is preferably in the range of 20/80 to 80/20, particularly 40/60 to 80/20.

Cross-linking agent (C)
The crosslinking agent (C) that can be used in the heat conductive adhesive for metal heat transfer tubes of the present invention is at least one selected from the group consisting of melamine resins, blocked polyisocyanate compounds, and resol type phenol resins. it can.

  The melamine resin is a resin obtained by a reaction between melamine and an aldehyde, and includes both a partially methylolated melamine resin and a completely methylolated melamine resin. The melamine resin used in the adhesive of the present invention is generally 200 to 2,000, preferably 250 to 1,600, more preferably 300 to 1,200, from the viewpoints of adhesiveness and curability. It is preferred to have a weight average molecular weight within the range.

  Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, and the like, and formaldehyde is particularly preferable. In addition, a methylolated melamine resin obtained by partially or completely etherifying a methylol group with an appropriate alcohol can also be used. Examples of alcohols that can be used for etherification include methyl alcohol, ethyl alcohol, Examples include n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethyl-1-butanol, 2-ethyl-1-hexanol and the like.

  Among the melamine resins, a methyl ether melamine resin in which the methylol group of a partially or fully methylolated melamine resin is partially or completely etherified with methyl alcohol; the methylol group of the partially or completely methylolated melamine resin is butyl alcohol. Butyl etherified melamine resin partially or fully etherified with methyl-butyl mixed etherified melamine in which the methylol group of the partially or fully methylolated melamine resin is partially or completely etherified with both methyl alcohol and butyl alcohol Resins can be preferably used. Of these, methyl etherified melamine resins and methyl-butyl mixed etherified melamine resins are preferred from the viewpoints of adhesiveness and curability, and methyl etherified melamine resins can be particularly preferably used.

  In particular, imino group-containing methyl etherified melamine resins and imino group-containing methyl-butyl mixed etherified melamine resins can be suitably used from the viewpoint of curability.

  A commercially available product can be used as the melamine resin. Examples of commercially available product names include “Cymel 202”, “Cymel 203”, “Cymel 204”, “Cymel 211”, “Cymel 238”, “Cymel 251”, “Cymel 303”, “Cymel 323”, “Cymel 324”, “Cymel 325”, “Cymel 327”, “Cymel 350”, “Cymel 385”, “Cymel 701”, “Cymel 1156”, “Cymel 1158”, “Cymel 1116”, “Cymel 1130” ( As described above, manufactured by Nippon Cytec Industries, Inc.), “Uban 120”, “Uban 20HS”, “Uban 20SE60”, “Uban 2021”, “Uban 2028”, “Uban 28-60” (above, manufactured by Mitsui Chemicals, Inc.) Can be mentioned.

  Of the above, “Cymel 325”, “Cymel 327” and “Cymel 701” are used as the imino group-containing methyl etherified melamine resin, and “Cymel 202” is used as the imino group-containing methyl-butyl mixed etherified melamine resin. Can be mentioned.

  The melamine resins can be used alone or in combination of two or more.

  Moreover, in order to accelerate | stimulate the hardening reaction in which a resol type phenol resin and a melamine resin are involved, a hardening catalyst can be used as needed. As a curing catalyst for accelerating this curing reaction, generally, a sulfonic acid compound, a neutralized product of a sulfonic acid compound, a phosphoric acid compound, and the like can be used.

  Examples of the sulfonic acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and the like. Examples of the neutralizing agent in the neutralized product of the sulfonic acid compound include basic compounds such as primary amine, secondary amine, tertiary amine, ammonia, caustic soda, and caustic potash.

Blocked polyisocyanate compound The blocked polyisocyanate compound is a compound obtained by blocking free isocyanate groups of a polyisocyanate compound with a blocking agent. Examples of the polyisocyanate compound include aliphatic diisocyanate compounds such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; cyclic aliphatic diisocyanate compounds such as hydrogenated xylylene diisocyanate and isophorone diisocyanate; tolylene diisocyanate and 4,4′-diphenylmethane diisocyanate. An aromatic diisocyanate compound such as: triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4′- Organic polyisocyanates per se such as polyisocyanate compounds having three or more isocyanate groups such as dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate, or these Examples include adducts of organic polyisocyanates and polyhydric alcohols, low molecular weight polyester resins or water, cyclized polymers of the organic polyisocyanates described above, and isocyanate / biuret bodies. Of these, isocyanurate obtained by cyclopolymerization of hexamethylene diisocyanate can be preferably used.

  Examples of the blocking agent include phenol compounds such as phenol, cresol and xylenol; ε-caprolactam; δ-valerolactam, γ-butyrolactam and other lactam compounds; methanol, ethanol, n-, i- or t-butyl alcohol, ethylene Alcohol compounds such as glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and benzyl alcohol; oximes such as formamidoxime, acetaldoxime, acetoxime, methylethylketoxime, diacetylmonooxime, benzophenone oxime, cyclohexaneoxime Compounds; active compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, acetylacetone It can be suitably used blocking agent such as alkylene compounds. Of these, lactam compounds and oxime compounds are preferred.

  By mixing the polyisocyanate compound and the blocking agent, free isocyanate groups of the polyisocyanate compound can be easily blocked. The above blocked polyisocyanate compounds can be used alone or in combination of two or more.

  A curing catalyst can also be used to improve the curability of the blocked polyisocyanate compound. Examples of the curing catalyst include tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, and 2-ethyl. An organometallic catalyst such as lead hexanoate can be suitably used.

Resol-type phenol resin Resole-type phenol resin works as a crosslinking agent for acrylic-modified epoxy resin (A) and polyhydroxy polyether resin (B), and phenol compounds such as phenol and bisphenol A and aldehyde compounds such as formaldehyde This includes not only a phenol resin in which a methylol group is introduced by a condensation reaction in the presence of a reaction catalyst but also an alkyl etherified part of the introduced methylol group with an alcohol having 6 or less carbon atoms. The

  Examples of the phenol compound used in the production of the resol type phenol resin include phenol, o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol, m -Cresol, m-ethylphenol, 3,5-xylenol, m-methoxyphenol, bisphenol A, bisphenol F, etc. can be mentioned. These phenol compounds can be used alone or in combination of two or more.

  Examples of the formaldehyde compound used for the production of the resol type phenol resin include formaldehyde, paraformaldehyde, trioxane and the like. These can be used individually by 1 type or in mixture of 2 or more types.

  The alcohol used for alkyl etherifying a part of the methylol group of the methylolated phenol resin is not particularly limited, but monohydric alcohol having 1 to 8 carbon atoms is preferable, and 1 having 1 to 4 carbon atoms. A monohydric alcohol is more preferable. Specifically, it is particularly preferable to use a monohydric alcohol such as methanol, ethanol, n-propanol, n-butanol, or isobutanol.

  The resol type phenol resin has a weight average molecular weight of preferably 300 to 4,000, more preferably 400 to 3,000, and an average number of methylol groups per nucleus of the benzene nucleus of 0.3 to 3,000. It is suitable that it is in the range of 3.0, preferably 0.5 to 3.0, more preferably 0.7 to 3.0. By using the resol type phenol resin, the adhesiveness as an adhesive can be improved.

  The amount of the crosslinking agent (C) in the heat conductive adhesive for metal heat transfer tubes of the present invention is selected from the viewpoints of adhesiveness and curability, such as acrylic-modified epoxy resin (A), polyhydroxy polyether resin (B) and It is 1-30 mass% with respect to solid content total amount of a crosslinking agent (C), Preferably it is 3-25 mass%, More preferably, it exists in the range of 5-20 mass%.

Thermally conductive filler (D)
The heat conductive adhesive for metal heat transfer tubes of the present invention contains a heat conductive filler (D) for the purpose of improving the heat conductivity during heat curing. Examples of the thermally conductive filler (D) include metal powder, scaly metal (for example, scaly aluminum, scaly nickel), metal oxide (alumina, zinc oxide, etc.), carbon powder, graphite, scaly carbon, and carbon nanotube. , Diamond powder, boron nitride, aluminum nitride, silicon nitride, silicon carbide and the like. Here, specific examples of the metal species of the metal powder and the scaly metal include silver, nickel, copper, zinc, aluminum, stainless steel, iron, brass, chromium and tin. Among these, flaky aluminum, flaky nickel, flaky carbon, diamond powder, boron nitride, and the like are particularly preferable from the viewpoint of stability and thermal conductivity of the adhesive.

  As commercial products of scaly aluminum, Alpaste TCR-2060 (product name, average particle size 16 μm, manufactured by Toyo Aluminum Co., Ltd.), Alpaste WXM-5660 (product name, average particle size 9 μm, manufactured by Toyo Aluminum Co., Ltd.), Al Paste WXM-1160 (manufactured by Toyo Aluminum Co., Ltd., trade name, average particle size 32 μm), Alpaste WL-7678 (manufactured by Toyo Aluminum Co., Ltd., trade name, average particle size 17 μm), Alpaste EMR-D767E (manufactured by Toyo Aluminum Co., Ltd.) Trade name, average particle diameter 17 μm), aluminum paste GX-180 (manufactured by Asahi Kasei Chemicals Corporation, trade name, average particle diameter 17 μm), and the like. Examples of commercially available scale-like nickel include HCA-1 (manufactured by NOVAMET, trade name, average particle size 10 μm).

  As commercial products of scaly carbon, BF-3K (manufactured by Chuetsu Graphite Industry Co., Ltd., trade name, average particle diameter 3 μm), BF-10K (manufactured by Chuetsu Graphite Industries Co., Ltd., trade name, average particle diameter) 10 μm), UF-2 (manufactured by Fuji Graphite Industry, trade name, average particle size 5.2 μm), CBF-1 (trade name, manufactured by Fuji Graphite Industry, average particle size 8.4 μm) and the like.

  Examples of commercially available boron nitride include UHP-1 (trade name, average particle diameter of 8 μm, manufactured by Showa Denko KK) for hexagonal boron nitride, and ISBN-M 4-8 (Tomei Diamond Co., Ltd.) for cubic boron nitride. Manufactured, trade name, average particle diameter 7 μm), ISBN-M 4-8 (trade name, average particle diameter 7 μm), ISBN-M 10-20 (trade name, average particle diameter, manufactured by Tomei Diamond Co., Ltd.) 14 μm).

  Examples of the diamond powder include IRM 3-8 (manufactured by Tomei Diamond Co., Ltd., trade name, average particle diameter of 4 μm).

  The average particle diameter (Note 1) of such a thermally conductive filler (D) is 3 to 50 μm, preferably 5 to 40 μm, in order to improve the performance of thermal conductivity, heat resistance, moisture resistance and heat cycle resistance. Also desirable.

  (Note 1) Average particle diameter: The average particle diameter is determined by measuring the major axis of the heat conductive filler (D) in an electron micrograph taken with a scanning electron microscope (5,000 magnifications), and obtaining the average value of n = 20. Thus, the average particle diameter (nm) was used.

  In addition, the quantity of the heat conductive filler (D) in the heat conductive adhesive for metal heat-transfer tubes of this invention is an acrylic modified epoxy resin (A), polyhydroxy polyether resin ( It is 1-60 mass parts with respect to 100 mass parts of total amounts of the solid content of B) and a crosslinking agent (C), Preferably it is 3-50 mass parts, More preferably, it exists in the range of 5-40 mass parts.

  The heat conductive adhesive for a metal heat transfer tube of the present invention may further include a color pigment, a bright pigment, an additive (an antiblocking agent, a lubricity imparting agent, an antifoaming agent, an antisettling agent, a thickening agent, if necessary. Agents, dispersants, etc.), organic solvents and the like can be added.

  Examples of the anti-blocking agent include extender pigments (eg, silica fine powder, barium sulfate, barium carbonate, calcium carbonate, talc, mica, clay, kaolin, spherical silica, spherical nickel, alumina white, etc.), organic fine particles (nylon fine particles, Polyolefin fine particles, acrylic resin fine particles, polyester resin fine particles, silicone rubber fine particles, urethane resin fine particles, phenol resin fine particles, polytetrafluoroethylene fine particles, and the like.

  The lubricity imparting agent is added to impart lubricity to the adhesive surface. Examples of the lubricity imparting agent include fatty acid ester wax; polyolefin wax such as polyethylene wax; lanolin, beeswax and the like. Animal waxes; plant waxes such as carnauba wax and water wax; waxes such as microcrystalline wax, silicon wax and fluorine wax.

  The heat conductive adhesive for metal heat transfer tubes of the present invention has a Ford Cup No. No. 4, with a viscosity of 50 to 300 seconds and a solid content mass concentration of 20 to 60 mass%, preferably 25 to 50 mass%. A heat conductive adhesive for a metal heat transfer tube can be applied to a metal that is an adhesive, dried, and cured, thereby bonding the metal that is the adhesive. Therefore, the adhesive of the present invention can be widely used for applications in bonding between metals. There is no restriction | limiting in particular as a to-be-coated object, Metals, such as iron, aluminum, zinc, copper, tin, various metal plating steel plates, can be mentioned.

  Application of heat conductive adhesive for metal heat transfer tubes to these metal surfaces is a method known per se, such as spray coating, brush coating, roller coating, dip coating, roll coating coating, curtain flow coater coating, etc. Can be done. The coating amount of the heat conductive adhesive for the metal heat transfer tube of the present invention is preferably in the range of 10 to 1,000 mg / dm 2, particularly 20 to 500 mg / dm 2.

  In the case of performing preliminary drying, the preliminary drying is usually performed to volatilize the solvent in the coating solution, and is performed at a temperature of about 80 to 250 ° C., particularly about 90 to 220 ° C., for 5 seconds to 40 minutes, particularly 10 seconds to 30 seconds. It is preferable to carry out in minutes.

  The heat conductive adhesive for the metal heat transfer tube of the present invention is cured by heating at a temperature of about 100 to 260 ° C., particularly about 120 to 240 ° C. for 5 seconds to 40 minutes, particularly about 10 seconds to 30 minutes. Can be done. By heat-curing the adhesive, the metal material that is an adhesive can be firmly bonded.

Heat exchanger tube for heat exchanger
The heat exchanger tube for a heat exchanger of the present invention is obtained by applying the above heat conductive adhesive. As a metal material used for a metal heat transfer tube for a heat exchanger, an aluminum-based metal is usually used from the viewpoint of heat transfer and weight reduction, but depending on the required characteristics of the heat exchanger, copper-based, iron-based, and magnesium It may be a metal material such as titanium or titanium. The aluminum-based metal includes aluminum and an aluminum-based alloy.

  The type of metal heat transfer tube for heat exchanger is a structure in which the inside of a flat tube is divided into a plurality of flow paths by a plurality of partition walls in addition to a round tube having a circular shape in a cross section perpendicular to the tube axis A generally adopted tube such as a flat multi-hole tube (see FIG. 3) having Among them, in the case of a circular cross section (round tube), for example, a number of grooves, for example, a number of spiral grooves extending so as to have a predetermined lead angle with respect to the tube axis are formed on the inner surface. Thus, a so-called inner surface grooved heat transfer tube in which inner surface fins having a predetermined height are formed between the grooves is exemplified. In addition, examples of the flat multi-hole tube include those obtained by porthole extrusion.

  The heat exchanger tube for a heat exchanger according to the present invention can be obtained by applying the adhesive to the outer peripheral surface of the metal heat exchanger tube and drying it. Examples of the method for applying the adhesive include known methods such as brush coating, roll coater coating, spraying, and sponge coating.

  Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples. However, the present invention is not limited to these. In each example, “parts” and “%” are based on mass unless otherwise specified. The film thickness is based on the cured coating film.

Production of Epoxy Resin Production Example 1 Production of Epoxy Resin (a1) 579 parts of jER806 (Note 2), 165 parts of jER828EL (Note 3), 410 parts of bisphenol F and 0.6 part of tetrabutylammonium bromide, reflux condenser, thermometer And a four-necked flask equipped with a stirrer, and reacted at 160 ° C. under a nitrogen stream. The reaction was monitored by epoxy equivalent, and was allowed to react for about 6 hours to obtain a bisphenol F and bisphenol A combined type epoxy resin (a1) having a number average molecular weight of about 8,000 and an epoxy equivalent of about 6,500 g / eq.

In the raw material component of the epoxy resin (a1), the content of bisphenol F and / or bisphenol F-type epoxy resin with respect to the total amount of bisphenol and bisphenol-type epoxy resin is 85.7% by mass.
(Note 2) jER806: manufactured by Mitsubishi Chemical Corporation, bisphenol F type epoxy resin, epoxy equivalent of about 170, molecular weight of about 320
(Note 3) jER828EL: Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, epoxy equivalent of about 187, molecular weight of about 350.

Production Example 2 Production of Epoxy Resin (a2) 800 parts of jER806 (Note 2), 448 parts of bisphenol F, and 0.6 parts of tetrabutylammonium bromide were placed in a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer. The reaction was carried out at 160 ° C. under a nitrogen stream. The reaction was monitored by epoxy equivalent, and was allowed to react for about 6 hours to obtain a bisphenol F type epoxy resin (a2) having a number average molecular weight of about 8,000 and an epoxy equivalent of about 7,000 g / eq.

  Moreover, in the raw material component of the epoxy resin (a2), the content of bisphenol F and / or bisphenol F-type epoxy resin with respect to the total amount of bisphenol and bisphenol-type epoxy resin is 100% by mass.

Production Example 3 Production of Epoxy Resin (a3) 268 parts of jER806 (Note 2), 546 parts of jER828EL (Note 3), 456 parts of bisphenol A and 0.6 part of tetrabutylammonium bromide were added with a reflux condenser, a thermometer and a stirrer. The reaction was carried out at 160 ° C. under a nitrogen stream in a four-necked flask equipped. The reaction was monitored by epoxy equivalent and reacted for about 6 hours to obtain a bisphenol F and bisphenol A combined type epoxy resin (a3) having a number average molecular weight of about 7,800 and an epoxy equivalent of about 5,600 g / eq.

  In the raw material component of the epoxy resin (a3), the content of bisphenol F and / or bisphenol F-type epoxy resin with respect to the total amount of bisphenol and bisphenol-type epoxy resin is 21.1% by mass.

Production Example 4 Production of Epoxy Resin (b1) 558 parts of jER828EL (Note 3), 329 parts of bisphenol A and 0.6 part of tetrabutylammonium bromide were charged into a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer. The reaction was performed at 160 ° C. under a nitrogen stream. The reaction was monitored by epoxy equivalent, and was allowed to react for about 5 hours to obtain a bisphenol A type epoxy resin (b1) having a number average molecular weight of about 11,000 and an epoxy equivalent of about 8,000 g / eq.

  In the raw material component of the epoxy resin (b1), the content of bisphenol F and / or bisphenol F-type epoxy resin with respect to the total amount of bisphenol and bisphenol-type epoxy resin is 0% by mass.

  Table 1 shows the blending contents of Production Examples 1 to 4.

Production of Acrylic Resin Production Example 5 Production of Acrylic Resin (c1) Solution A 4-necked flask equipped with a reflux condenser, thermometer, monomer flow controller and stirrer was charged with 1096 parts of n-butanol under nitrogen flow. Heated to ° C. Next, a mixture of 210 parts of methacrylic acid, 180 parts of styrene, 210 parts of ethyl acrylate and 18 parts of t-butylperoxy-2-ethylhexanoate (polymerization initiator) was dropped over about 3 hours, and the dropping was completed. Thereafter, the mixture was further stirred at the same temperature for 2 hours and cooled to room temperature to obtain an acrylic resin (c1) solution having a solid content of about 35% by mass. The obtained acrylic resin (c1) had an acid value of 228 mgKOH / g and a weight average molecular weight of about 25,000.

Production Example 6 Production of Acrylic Resin (c2) Solution In a four-necked flask equipped with a reflux condenser, thermometer, monomer flow controller and stirrer, 1360 parts of n-butanol was charged and heated to 110 ° C. under a nitrogen stream. . Next, a mixture of 63 parts of methacrylic acid, 30 parts of styrene, 117 parts of ethyl methacrylate, 90 parts of ethyl acrylate, and 54 parts of t-butylperoxy-2-ethylhexanoate (polymerization initiator) was added for about 5 hours. After completion of the dropwise addition, the mixture was further stirred at the same temperature for 2 hours and cooled to room temperature to obtain an acrylic resin (c2) solution having a solid content of about 35% by mass. The obtained acrylic resin (c2) had an acid value of 137 mgKOH / g and a weight average molecular weight of about 7,800.

Production of Acrylic Modified Epoxy Resin (A) Production Example 7 Production of Acrylic Modified Epoxy Resin (A1-1) Aqueous Dispersion Obtained in Production Example 1 in a four-necked flask equipped with a reflux condenser, thermometer and stirrer. 60 parts of the epoxy resin (a1), 25 parts of the epoxy resin (b1) obtained in Production Example 4, 42.9 parts (solid content 15 parts) of the acrylic resin (c1) solution obtained in Production Example 5, and 55% of diethylene glycol monobutyl ether. 6 parts were charged and heated to 100 ° C. to dissolve.

  Next, 3.7 parts of N, N-dimethylaminoethanol was added, and the mixture was kept at 100 ° C. and allowed to react for about 1.5 hours, whereby an acrylic modified epoxy resin (A1-1) solution having a resin acid value of 25 mgKOH / g was obtained. Obtained.

  Thereafter, the temperature of the resin solution was set to 70 ° C., and 218 parts of deionized water was gradually added to perform water dispersion. Next, an acrylic dispersion-modified epoxy resin (A1-1) aqueous dispersion having a solid content of about 30% by mass was obtained by concentrating under reduced pressure to remove excess solvent.

  The weight average molecular weight of the resin solid content of the acrylic-modified epoxy resin (A1-1) was about 123,000, the glass transition temperature was 125 ° C., and the average particle size of the aqueous dispersion was 240 nm.

Production Example 8 Production of Acrylic Modified Epoxy Resin (A1-2) Aqueous Dispersion In a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer, 60 parts of epoxy resin (a2) obtained in Production Example 2 and jER1256 (Note 4) 62.5 parts (25 parts solid content), 42.9 parts of the acrylic resin (c1) solution obtained in Production Example 5 (15 parts solid content) and 18.1 parts diethylene glycol monobutyl ether were charged at 85 ° C. Was dissolved by heating.

  Next, 3.7 parts of N, N-dimethylaminoethanol was added, and the mixture was kept at 85 ° C. and allowed to react for about 1.5 hours, whereby an acrylic modified epoxy resin (A1-2) solution having a resin acid value of 25 mgKOH / g was obtained. Obtained.

  Thereafter, the temperature of the resin solution was set to 70 ° C., and 218 parts of deionized water was gradually added to perform water dispersion. Next, an aqueous dispersion of an acrylic-modified epoxy resin (A1-2) having a solid content of about 30% by mass was obtained by concentration under reduced pressure in order to remove excess solvent.

  The weight average molecular weight of the resin solid content of the acrylic-modified epoxy resin (A1-2) was about 134,000, the glass transition temperature was 115 ° C., and the average particle size of the aqueous dispersion was 210 nm.

  (Note 4) jER1256: manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin solution having a weight average molecular weight of about 12,000 and an epoxy equivalent of about 8,000, solid content of about 40%.

Production Example 9 Production of Acrylic Modified Epoxy Resin (A1-3) Aqueous Dispersion 85 parts of the epoxy resin (a2) obtained in Production Example 2 was produced in a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer. 42.9 parts (15 parts of solid content) of the acrylic resin (c1) solution obtained in Example 5 and 55.6 parts of diethylene glycol monobutyl ether were charged and heated to 100 ° C. for dissolution. Next, 3.7 parts of N, N-dimethylaminoethanol was added and kept at 100 ° C. and allowed to react for about 1.5 hours, whereby an acrylic modified epoxy resin (A1-3) solution having a resin acid value of 25 mgKOH / g was obtained. Obtained.

  Thereafter, the temperature of the resin solution was set to 70 ° C., and 218 parts of deionized water was gradually added to perform water dispersion. Next, an aqueous dispersion of an acrylic-modified epoxy resin (A1-3) having a solid content of about 30% by mass was obtained by concentration under reduced pressure in order to remove excess solvent.

  The weight average molecular weight of the resin solid content of the acrylic-modified epoxy resin (A1-3) was about 106,000, the glass transition temperature was 100 ° C., and the average particle size of the aqueous dispersion was 220 nm.

Production Example 10 Production of Acrylic Modified Epoxy Resin (A1-4) Aqueous Dispersion 85 parts of the epoxy resin (a3) obtained in Production Example 3 was produced in a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer. 42.9 parts (15 parts of solid content) of the acrylic resin (c1) solution obtained in Example 5 and 55.6 parts of diethylene glycol monobutyl ether were charged and heated to 100 ° C. for dissolution. Next, 3.7 parts of N, N-dimethylaminoethanol was added, and the mixture was kept at 100 ° C. and allowed to react for about 1.5 hours, whereby an acrylic-modified epoxy resin (A1-4) solution having a resin acid value of 28 mgKOH / g was obtained. Obtained.

  Thereafter, the temperature of the resin solution was set to 70 ° C., and 218 parts of deionized water was gradually added to perform water dispersion. Next, an aqueous dispersion of an acrylic-modified epoxy resin (A1-4) having a solid content of about 30% by mass was obtained by concentration under reduced pressure in order to remove excess solvent.

  The weight average molecular weight of the resin solid content of the acrylic-modified epoxy resin (A1-4) was about 132,000, the glass transition temperature was 130 ° C., and the average particle size of the aqueous dispersion was 220 nm.

Production Example 11 Production of Acrylic Modified Epoxy Resin (A2-1) In a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer, 85 parts of the epoxy resin (b1) obtained in Production Example 4 and Production Example 5 42.9 parts (15 parts of solid content) of the obtained acrylic resin (c1) solution and 55.6 parts of diethylene glycol monobutyl ether were charged and heated to 100 ° C. to dissolve. Next, 3.7 parts of N, N-dimethylaminoethanol was added, and the mixture was kept at 100 ° C. and reacted for about 1.5 hours, whereby an acrylic modified epoxy resin (A2-1) solution having a resin acid value of 25 mg KOH / g was obtained. Obtained.

  Thereafter, the temperature of the resin solution was set to 70 ° C., and 218 parts of deionized water was gradually added to perform water dispersion. Next, an acrylic dispersion-modified epoxy resin (A2-1) aqueous dispersion having a solid content of about 30% by mass was obtained by concentrating under reduced pressure in order to remove excess solvent.

  The weight average molecular weight of the resin solid content of the acrylic-modified epoxy resin (A2-1) was about 108,000, the glass transition temperature was 130 ° C., and the average particle size of the aqueous dispersion was 250 nm.

Production Example 12 Production of Acrylic Modified Epoxy Resin (A2-2) Four-necked flask equipped with reflux condenser, thermometer and stirrer, Four-neck flask equipped with reflux condenser, thermometer and stirrer, 75 parts of the epoxy resin (a2) obtained in Production Example 2, 71.5 parts of the acrylic resin (c2) solution obtained in Production Example 6 (25 parts of solid content) and 55.6 parts of diethylene glycol monobutyl ether were charged at 100 ° C. Heat to dissolve. Next, 3.7 parts of N, N-dimethylaminoethanol was added, and the mixture was kept at 100 ° C. and allowed to react for about 1.5 hours, whereby an acrylic modified epoxy resin (A2-2) solution having a resin acid value of 28 mgKOH / g was obtained. Obtained.

  Thereafter, the temperature of the resin solution was set to 70 ° C., and 218 parts of deionized water was gradually added to perform water dispersion. Next, an aqueous dispersion of an acrylic-modified epoxy resin (A2-2) having a solid content of about 30% by mass was obtained by concentration under reduced pressure in order to remove excess solvent.

  The weight average molecular weight of the resin solid content of the acrylic-modified epoxy resin (A2-2) was about 19,000, the glass transition temperature was 95 ° C., and the average particle size of the aqueous dispersion was 260 nm.

  Table 2 shows the blending contents of Production Examples 7 to 12.

Production of resol type phenolic resin (C) Production Example 13 Production of resol type phenolic resin (C1)
94 parts of carboxylic acid, 243 parts of 37% formaldehyde aqueous solution and 1 part of caustic soda were added to the reaction vessel, reacted at 60 ° C. for 3 hours, and dehydrated at 50 ° C. for 1 hour under reduced pressure. Subsequently, the mixture was filtered to remove caustic soda to obtain a resol type phenol resin (C1) solution having a solid content of about 50%. The resin solid content of the obtained resol type phenol resin (C1) was a weight average molecular weight of about 1,100, and the average number of methylol groups per benzene nucleus was 1.9.

Production Example 14 Production of Resol Type Phenolic Resin (C2) In a reaction vessel, 150 parts of bisphenol F, 243 parts of 37% formaldehyde aqueous solution and 1 part of caustic soda were added and reacted at 60 ° C. for 3 hours, and then at 50 ° C. under reduced pressure. Dehydrated for 1 hour. Subsequently, the mixture was filtered to remove caustic soda to obtain a resol type phenol resin (C2) solution having a solid content of about 50%.

  The resin solid content of the obtained resol type phenol resin (C2) has a bisphenol F skeleton, the weight average molecular weight is about 1,800, and the average number of methylol groups per benzene nucleus is 2.1. there were.

Example 1 Production of Thermally Conductive Adhesive for Metal Heat Transfer Tube Production of 1 Acrylic modified epoxy resin (A1-1) 40 parts (solid content), polyhydroxy polyether resin B1 (Note 5) 40 parts (solid content), resol type phenolic resin (C1) 10 parts (solid content, Al 30 parts of paste WXM-1160 (Note 15) was blended and dispersed for 30 minutes in a paint shaker containing glass media, thereby obtaining a heat conductive adhesive No. 1 having a solid content of 40%.

Examples 2-35 and Comparative Examples 1-14
Except for the compositions shown in Tables 3 to 5 below, the heat conductive adhesive No. 2-No. 49 was obtained.

Preparation of test plate 1 On the aluminum material (changed according to the test), each heat conductive adhesive was applied with a bar coater so that the dry film thickness was 10 μm, and preliminarily kept at 100 ° C. for 2 minutes with a hot air dryer. The test shown below was done after drying.

Production of test plate 2 Extruded flat multi-hole tube having a width of 16 mm, a thickness of 2 mm, and 7 holes exhibiting a cross-sectional shape as shown in FIG. 3 by extruding an aluminum alloy (JIS A3003) as a heat transfer tube Prepared. On this multi-hole tube, each heat conductive adhesive was applied with a bar coater so that the dry film thickness was 10 μm, and preliminarily dried at 100 ° C. for 2 minutes with a hot air drier, and the test “(Note 23) 180”. Degree peel peel strength ". The performance tests in Tables 3 to 5 were performed according to the following evaluation criteria.

(Note 5) Polyhydroxy polyether resin B1: Emulsion of addition reaction product of bisphenol A type epoxy resin and monoethanolamine, containing 40% by mass of polyhydroxy polyether resin B1 as a solid content, weight average molecular weight 5,800 , Epoxy equivalent 150,000 g / eq (per solids).
(Note 6) Polyhydroxy polyether resin B2: emulsion of addition reaction product of bisphenol A type epoxy resin and acetic acid, containing 40% by mass of polyhydroxy polyether resin B2 as a solid content, weight average molecular weight 5,500, epoxy Equivalent 180,000 g / eq (per solid). (Note 7) Polyhydroxypolyether resin B3: emulsion of addition reaction product of bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name, jER4007P) and monoethanolamine, polyhydroxypolyether resin B3 as solid content Containing 40 mass%, weight average molecular weight 10,800, epoxy equivalent 200,000 g / eq (per solid content).
(Note 8) Polyhydroxy polyether resin B4: emulsion of a bisphenol A type epoxy resin (trade name, jER1007, manufactured by Mitsubishi Chemical Corporation) with a surfactant, containing 40% by mass of polyhydroxy polyether resin B4 as a solid content, Weight average molecular weight 5,400, epoxy equivalent 3,400 g / eq (per solid content).
(Note 9) Cymel 701: Nihon Cytec Industries, Inc., imino group-containing methyl etherified melamine resin (including methylol group), trade name, solid content 82%, weight average molecular weight 700.
(Note 10) Cymel 325: manufactured by Nippon Cytec Industries Co., Ltd., imino group-containing methyl etherified melamine resin (including methylol group), trade name, solid content 80%, weight average molecular weight 800.
(Note 11) Block polyisocyanate compound A: hexamethylene diisocyanate trimer oxime blocked, solid content 37% by mass, NCO content 3.6%.
(Note 12) Block polyisocyanate compound B: lactam blocked product of hexamethylene diisocyanate, solid content 100 mass%, NCO content 14.3%.
(Note 13) BF-3K: manufactured by Chuetsu Graphite Industry Co., Ltd., trade name, average particle size of 3 μm, scaly carbon (Note 14) BF-10K: manufactured by Chuetsu Graphite Industry Co., Ltd., product name, average particle Commercial product of diameter 10 μm, scaly carbon (Note 15) Alpaste WXM-1160: manufactured by Toyo Aluminum Co., Ltd., trade name, average particle diameter 32 μm, commercial product of scaly aluminum (Note 16) Alpaste WL-7678: Toyo Aluminum Product name, average particle size of 17 μm, commercially available product of scaly aluminum (Note 17) HCA-1: NOVAMET Co., Ltd., product name, average particle size of 10 μm, commercially available product of scaly nickel.
(Note 17B) UHP-1: Showa Denko Co., Ltd., trade name, average particle size of 8 μm, commercially available boron nitride (Note 17C) ISBN-M 4-8: Tomei Dia Co., Ltd., trade name, average particle size of 7 μm, Commercial product of diamond powder (Note 17D) IRM 3-8: manufactured by Tomei Diamond Co., Ltd., trade name, average particle diameter of 4 μm, commercial product of diamond powder

(Note 18) Storage stability of adhesive: The storage stability of each adhesive adjusted so that the solid content concentration was 40% by mass was evaluated according to the following criteria:
A: Even if the adhesive after being stored at 30 ° C. for one month is applied, no abnormal surface (scratch) is observed;
○: Even if the adhesive after coating at 30 ° C. for 2 weeks is applied, no coating surface abnormality (spots) is observed, but after 1 month storage, coating surface abnormality (spots) is observed;
Δ: Even if the adhesive after coating for 1 week at 30 ° C. is applied, no coating surface abnormality (buzz) is observed, but when the adhesive after 2 weeks storage is applied, a coating surface abnormality (buzz) is observed;
X: When the adhesive after storage for 1 week at 30 ° C. is applied, abnormalities on the coating surface (spots) are observed.

(Note 19) Blocking resistance: Test plate 1 (# 5052 aluminum, plate thickness 0.25 mm) was cut into two pieces having a size of 10 cm × 10 cm, and the painted surfaces were combined with each other at a pressure of 5 kgf / cm 2. The degree of peeling (ease of peeling) after standing at a temperature of 50 ° C. for 15 minutes was evaluated according to the following criteria:
A: Can be removed without resistance;
○: No peeling of the coating film is observed, but there is a slight resistance when peeling;
Δ: Slight peeling of coating film is observed, and there is resistance when peeling;
X: The resistance at the time of peeling is large, the coating film is considerably peeled off, or the test plates cannot be peeled off.

(Note 20) Shear adhesive strength: Test plate 1 (# 5052 aluminum, painted to a thickness of 0.25 mm) was cut into two pieces of 10 cm × 1 cm, and 0.5 cm 2 of the coated surface side end The areas were combined and pressed at a pressure of 18 kgf / cm 2 and a temperature of 150 ° C. for 20 minutes. Thereafter, the shear bond strength was measured by autograph:
A: Shear bond strength is 40 kgf / 0.5 cm 2 or more;
○: Shear adhesive strength of 10 kgf / 0.5 cm 2 or more and less than 40 kgf / 0.5 cm 2;
Δ: Shear adhesive strength of 5 kgf / 0.5 cm 2 or more and less than 10 kgf / 0.5 cm 2;
X: Shear adhesive strength is less than 5 kgf / 0.5 cm2.

(Note 21) T peel peel strength: The above test plate 1 (painted on # 1000 aluminum (plate thickness 0.1 mm)) was cut into two pieces of 10 cm × 1 cm, and the coated surfaces were combined together to apply pressure 6 kgf. / Cm <2> at a temperature of 150 [deg.] C. for 20 minutes. Thereafter, the T peel peel strength was measured by autograph:
A: T peel peel strength is 1.0 kgf or more / 1 cm width;
○: T peel peel strength of 0.5 kgf or more / 1 cm width and less than 1.0 kgf / 1 cm width;
Δ: T peel peel strength is 0.3 kgf or more / 1 cm width and less than 0.5 kgf / 1 cm width;
X: T peel peel strength is less than 0.3 kgf / 1 cm width.

(Note 22) Thermal conductivity: Each adhesive was coated on a tin plate with a bar coater to a dry film thickness of 50 μm, pre-heated at 100 ° C. for 15 minutes, and then heat-dried at 150 ° C. for 1 hour. did. Subsequently, each coating film was peeled off (amalgam method) to obtain a film. This film was cut into a certain size (70 mm × 140 mm), and the thermal conductivity was measured using QTM-03 (Kyoto Electronics Co., Ltd., trade name, thermal conductivity meter):
◎ indicates a thermal conductivity of 1.2 W / mK or more;
○ has a thermal conductivity of 0.8 W / mK or more and less than 1.2 W / mK;
Δ has a thermal conductivity of 0.4 W / mK or more and less than 0.8 W / mK;
X has a thermal conductivity of less than 0.4 W / mK.

(Note 23) 180 degree peel strength: Using test plate 2 (painted on a flat multi-hole conductive tube), uncoated # 1000 aluminum (plate thickness 0.1 mm) is 10 cm × 1 cm in size. Cut and bonded by pressure bonding at a temperature of 150 ° C. for 20 minutes at a pressure of 6 kgf / cm 2. The 180 degree peel peel strength was then measured by autograph:
A: 180 degree peel strength is 1.2 kgf or more / 1 cm width;
○: 180 degree peel strength is 0.8 kgf or more / 1 cm width and less than 1.2 kgf / 1 cm width;
Δ: 180 degree peel peel strength of 0.4 kgf or more / 1 cm width and less than 0.8 kgf / 1 cm width;
X: 180 degree peel strength is less than 0.4 kgf / 1 cm width.

  (Note 24) Overall evaluation: In the field of thermally conductive adhesives for metal heat transfer tubes to which the present invention belongs, the adhesives are storage stability, blocking resistance during production, curability, adhesiveness and heat. All the performance of conductivity is required to be excellent. Therefore, comprehensive evaluation was performed according to the following criteria.

A: All items of storage stability, blocking resistance, shear bond strength, T peel peel strength, thermal conductivity, and 180 degree peel peel strength of the adhesive are A or B, and at least one is A;
○: All the above 6 items are ○;
Δ: The above six items are all ◎, ○ or Δ, and at least one is Δ;
X: At least one of the above six items is x.

  A heat exchanger tube for a heat exchanger having excellent adhesiveness can be provided.

Claims (5)

Acrylic modified epoxy resin (A) having a weight average molecular weight of 20,000 to 400,000, a polyhydroxy polyether resin having a weight average molecular weight of 800 to 20,000 (excluding an acrylic modified epoxy resin) (B), A heat conductive adhesive containing at least one crosslinking agent (C) selected from the group consisting of a melamine resin, a blocked polyisocyanate compound, and a resol type phenol resin, and a heat conductive filler (D),
1-60 mass parts of heat conductive filler (D) is contained with respect to 100 mass parts of total amounts of solid content of acrylic modified epoxy resin (A), polyhydroxy polyether resin (B), and crosslinking agent (C). Thermally conductive adhesive for metal heat transfer tubes.   The heat for a metal heat transfer tube according to claim 1, wherein the thermally conductive filler (D) is at least one selected from the group consisting of flaky aluminum, flaky nickel, flaky carbon, boron nitride, and diamond powder. Conductive adhesive.   The heat conductive adhesive for metal heat exchanger tubes according to claim 1 or 2, wherein the polyhydroxy polyether resin (B) contains a polymer (b1) obtained by polycondensation of a phenol compound and an epihalohydrin.   A monovalent amine compound having reactivity with an epoxy group in the polymer (b1), a polymer (b1) obtained by polycondensation of a phenol compound and an epihalohydrin with a polyhydroxy polyether resin (B), and The metal heat exchanger tube according to any one of claims 1 to 3, comprising a polymer (b12) obtained by reacting at least one (b2) selected from the group consisting of monovalent acid compounds. Thermally conductive adhesive.   The metal heat exchanger tube for heat exchangers which apply | coats the heat conductive adhesive for metal heat exchanger tubes of any one of Claims 1-4.