JP2007045923A - Multilayer adhesion sheet, heat exchanger and molding material for forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer adhesion sheet wherein breaking at a connection part by breaking a resin is not observed and also moldability is excellent. <P>SOLUTION: The multilayer adhesion sheet is composed of a metal sheet on at least one surface of which a thermoplastic resin layer A and a thermoplastic resin layer B are formed, the both resins having different functions from each other, and the resin layer B contains a phenolic hydroxy group-containing aromatic polyamide/polybutadience/acrylonitrile copolymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a multi-layer adhesive sheet for producing a structure by processing parts into an optimal shape, assembling, and then heat-curing, even if the sheet thickness is reduced to reduce the weight of the heat exchanger. Multilayer adhesive sheet that has excellent adhesive strength and that can be joined without being lifted even when assembled in a curved shape, a heat exchanger forming material, and a heat exchanger manufactured using them It is about.

  Conventionally, when manufacturing an aluminum heat exchanger, an aluminum sheet is used as a material, parts are processed into a certain shape and assembled. The aluminum sheet has a structure in which the same aluminum material having a melting point lower than that of the aluminum material as the core material is laminated as a brazing material on one or both sides of the aluminum material having a thickness of about 500 to 1000 μm as the core material (Patent Document) 1) is used.

  On the other hand, in the case of a brazing material made of aluminum, its melting temperature is usually around 577 ° C., so it must be raised to that temperature or higher (about 600 ° C.) at the time of joining. Since the energy consumed is large, an aluminum sheet (see Patent Document 2) having a structure in which a resin that can be heat-cured at 300 ° C. or lower is coated instead of an aluminum brazing material.

  In recent years, in particular, in-vehicle air conditioners and the like have been required to reduce the weight of heat exchangers. For this purpose, it is effective to make the aluminum material as a core material have a thickness of 500 μm or less. However, since the strength decreases when the aluminum material is thinned, it is necessary to use a high-strength aluminum alloy to which elements such as magnesium, copper, and silicon are added in order to improve the strength of the core material.

  However, although the strength of these alloys increases when the element addition amount is increased, there is a problem that the brazing property is remarkably lowered in the aluminum sheet laminated with the brazing material because the melting point is lowered. On the other hand, an aluminum sheet coated with a resin has also been proposed in order to reduce energy consumption, but there are problems such as insufficient adhesion strength at the curved part and poor heat resistance, and it changes to brazing. There is a need for adhesive sheet materials that are sufficiently reliable.

  Therefore, the applicant of the present invention has a specific tensile shear strength and elastic modulus as a multilayer adhesive sheet having at least two thermosetting resin layers having different functions on at least one side of the metal sheet, particularly as a thermosetting resin layer in contact with the metal sheet. And a multilayer adhesive sheet (see Patent Document 3) characterized by using a thermosetting resin layer having a glass transition temperature or the like. However, although this multilayer adhesive sheet can obtain excellent adhesive strength even when using a core material made of an aluminum material having a thickness of 500 μm or less, recently, the structure of the multilayer adhesive sheet has been improved in order to increase the efficiency of the heat exchanger. As the shape becomes complicated and the stress applied to the adhesive increases, there may be a problem that the adhesive layer portion that does not contact the metal is destroyed.

JP 2002-47523 A JP 2002-243395 A JP 2005-14380 A

  The present invention has been made paying attention to the above-described problems that occur when attempting to reduce the weight of a heat exchanger. That is, the present invention provides a multilayer adhesive sheet having a sufficiently reliable adhesive strength even when a core material made of an aluminum material having a thickness of 500 μm or less is used. In particular, in the case of a complicated structure, the multilayer adhesive sheet is curved. Although the adhesive must be fluidly filled into such thin gaps between the curved sheet parts, the occurrence of floating is suppressed even at the curved parts, resulting in a decrease in adhesive strength and damage to the cured product. PROBLEM TO BE SOLVED: To provide a multilayer adhesive sheet that does not break and has excellent heat resistance, and to provide a heat exchanger forming material comprising the multilayer adhesive sheet and a heat exchanger produced using the material. And

  As a result of intensive studies to solve the above problems, the present inventors have provided at least two layers of thermosetting resins having different functions on at least one side of a metal sheet, and have predetermined peeling on these thermosetting resins. By providing strength and tensile stress, it has sufficient adhesive strength even when the metal sheet thickness is reduced, and even when assembled in a curved shape, it can be joined without causing floating etc. It has been found that an adhesive sheet can be obtained, and the present invention has been made based on this finding. That is, according to the present invention, the following multilayer adhesive sheet, heat exchanger material, heat exchanger manufacturing method, and heat exchanger are provided.

[1] A multilayer adhesive sheet having a thermosetting resin layer A and a thermosetting resin layer B having different functions on at least one surface of the metal sheet, the layer B on the layer A, A multilayer adhesive sheet in which the layer B contains a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer.

[2] A multilayer adhesive sheet having a thermosetting resin layer A and a thermosetting resin layer B having different functions on at least one side of the metal sheet, and the layer B on the layer A, And the multilayer adhesive sheet whose maximum intensity | strength of T-type peeling by the following peeling test is 20 N / 25mm or more.
Peel test:
The multilayer adhesive sheet having the laminated structure is processed into the shape and size of a test piece based on JIS K 6854. The multilayer adhesive sheets thus processed are overlapped so that the surfaces of the thermosetting resin layer of the B layer face each other, sandwiched between 1.5 mm aluminum plates and clamped with a pinch cock, and placed in a hot air dryer at 200 ° C. And cured for 30 minutes to obtain a test piece for a peel test. Using this test piece, the peel strength was measured in accordance with JIS K 6854 at a test speed of 20 mm / min, and the maximum value was obtained from the measured values immediately after the start of measurement until the end of the measurement. And

[3] A multilayer adhesive sheet having a thermosetting resin layer A and a thermosetting resin layer B having different functions on at least one surface of the metal sheet, and the tensile stress of the layer B according to the following tensile test is 40 MPa. A multilayer adhesive sheet as described above.
Tensile test:
A test piece based on ASTM D-638 Type I is prepared from the material forming the B layer, and this is used as a test piece for a tensile test. Using this test piece, tensile stress is measured under the condition of a test speed of 5 mm / min according to JIS K7113.

[4] The multilayer adhesive sheet according to [2] or [3], wherein the thermosetting resin is an epoxy thermosetting resin.

[5] The multilayer adhesive sheet according to [4], wherein the B layer contains a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer.

[6] A layer made of a thermosetting resin having a tensile shear strength of 10 MPa or more and 100 MPa or less, and a gap filling characteristic when the thickness is 10 to 100 μm formed above the A layer and having a thickness of 5 to 60 mm The multilayer adhesive sheet according to any one of [1] to [5], which has a B layer made of a thermosetting resin, which is:

[7] The multilayer adhesive sheet according to any one of [1] to [6], wherein the metal sheet is made of an aluminum material.

[8] A heat exchanger forming material comprising the multilayer adhesive sheet according to any one of [1] to [7].

[9] A method for manufacturing a heat exchanger, wherein the heat exchanger is formed by bonding the heat exchanger forming material according to [8].

[10] A heat exchanger formed by bonding the material for forming a heat exchanger according to [8].

  The multilayer adhesive sheet of the present invention is excellent in adhesive strength and has a characteristic that even if the shape of the component is complicated and the laminated sheet has to be curved and laminated, it can be firmly bonded without causing floating. Have. This is because the hot melt of the thermosetting resin layer is fluidly filled in the thin gaps between the sheets in the curved portion of the multilayer adhesive sheet. Can adhere well. Moreover, even if the surface of the adherend has a complicated uneven surface, the adherend surface has a characteristic of being accurately curved along the uneven surface. In this case, since the hot melt of the thermosetting resin layer is fluidly filled in the thin gap between the adherend surface and the multilayer adhesive sheet in the curved portion of the multilayer adhesive sheet, The multilayer adhesive sheet can be adhered with high accuracy to an adherend surface having a complex uneven surface. Furthermore, since the fluidized adhesive (thermosetting resin layer) also has high strength, it can be applied to products that are subjected to higher stress. The multilayer adhesive sheet of the present invention is suitable as a heat exchanger forming material, and a lightweight and inexpensive heat exchanger can be easily produced by adhesion processing according to a conventional method using the multilayer adhesive sheet of the present invention. can do.

  Hereinafter, although an embodiment of the present invention is described concretely, the present invention is not limited to the following form.

  The multilayer adhesive sheet of the present invention is one in which at least two layers of thermosetting resins having different functions are provided on at least one surface of a metal sheet as a core material. As the metal sheet in this case, various conventionally known metals (including alloys) can be used. Examples of such a sheet include a sheet made of an aluminum alloy, a copper alloy, an iron alloy, a magnesium alloy, or the like. The metal sheet may be composed of only one layer or may have a multilayer structure of two or more layers.

  When the multilayer adhesive sheet of the present invention is used as a material for forming a heat exchanger, a metal sheet having a high thermal conductivity is used, and in addition to that, it is required to be lightweight and have high corrosion resistance. An aluminum material is optimal from the viewpoint. The aluminum material here is an aluminum alloy material. For the purpose of increasing the strength, improving the corrosion resistance, improving the workability, etc., the aluminum metal is replaced with magnesium, copper, silicon, manganese, iron, chromium, zirconium. In addition, an element such as titanium is usually added in an amount of 0.1 to 10 atomic%. Specific examples based on JIS symbols include A2017 (Al-Cu system), A3003 (Al-Mn system), A5052 (Al-Mg system), and the like. The thickness of the metal sheet is not particularly limited, but is usually 50 to 2000 μm, preferably 50 to 500 μm.

  Various surface treatments can be performed on the surface of the metal sheet as desired. Examples of the surface treatment in this case include treatments aimed at improving the adhesion between the aluminum surface and the resin layer, such as phosphoric acid chromate treatment and chromate chromate treatment. Moreover, an annealing process can also be performed as needed.

  At least two thermosetting resin layers of A and B layers each having a different function are formed on at least one side of the metal sheet as described above, and the B layer is formed above the A layer. By sequentially laminating, a multilayer adhesive sheet having a laminated structure according to the present invention is obtained.

  In one embodiment of the multilayer adhesive sheet of the present invention, the B layer contains a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer. Thus, when the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer is contained in the B layer, the peel strength of the multilayer adhesive sheet is adjusted to high strength, specifically 20 N / 25 mm or more, It becomes easy to adjust the tensile stress of the B layer to a high stress, specifically 40 MPa or more, and as a result, it is possible to prevent the occurrence of cracks (breakage or breakage) in the B layer. Can be obtained.

  Another aspect of the multilayer adhesive sheet of the present invention is a multilayer adhesive sheet having a laminated structure as described above, and has a maximum strength of 20 N / 25 mm or more according to the following peel test.

Peel test:
The multilayer adhesive sheet having the laminated structure is processed into the shape and size of a test piece based on JIS K 6854. The multilayer adhesive sheets processed in this way are superposed so that the surfaces of layer B face each other, sandwiched between 1.5 mm aluminum plates and clamped with a pinch cock, put in a hot air dryer and heated at 200 ° C. for 30 minutes. And make a test piece for a peel test. Using this test piece, the peel strength was measured in accordance with JIS K 6854 at a test speed of 20 mm / min, and the maximum value was obtained from the measured values immediately after the start of measurement until the end of the measurement. And

  By setting the maximum strength to 20 N / 25 mm or more, it is possible to prevent the B layer from being cracked (broken or broken) due to a stress such as refrigerant or air after the multilayer adhesive sheet is formed. Furthermore, if the maximum strength is 100 N / 25 mm or more, even when used in a product that is highly functional and subjected to high stress, it is caused by the crack (breakage or breakage) of the B layer and the crack of the B layer. It is preferable because it is possible to prevent breakage and destruction of the A layer, occurrence of peeling near the interface between the A layer and the metal sheet, and to obtain a more reliable product (for example, a heat exchanger) as a result.

  Further, in another aspect of the multilayer adhesive sheet of the present invention, as in the above aspect, at least two thermosetting resin layers of A layer and B layer made of thermosetting resins each having different functions are sequentially laminated. The tensile stress by the following tensile test of B layer which comprises this multilayer adhesive sheet is 40 Mpa or more.

Tensile test:
A test piece based on ASTM D-638 Type I is prepared from the material forming the B layer, and this is used as a test piece for a tensile test. Using this test piece, tensile stress is measured under the condition of a test speed of 5 mm / min according to JIS K7113.

  By setting the tensile stress to 40 MPa or more, it is possible to prevent the B layer from being cracked (broken or broken) due to a stress such as refrigerant or air after the multilayer adhesive sheet is formed. Further, if this tensile stress is 50 MPa or more, more preferably 60 MPa or more, even when the product is used in a product with high functionality and high stress, the B layer is cracked (damaged or broken). It is possible to prevent breakage and destruction of the A layer caused by the crack, and occurrence of peeling near the interface between the A layer and the metal sheet, and as a result, a highly reliable product (for example, a heat exchanger) can be obtained. .

  In the multilayer adhesive sheet, the curing temperature of the resin constituting each layer is preferably from normal temperature to 300 ° C. or less. If the curing temperature is lower than room temperature, the storage stability of the adhesive sheet will deteriorate, so it must be stored at a low temperature below room temperature, and parts processing and mounting must also be performed at a low temperature below room temperature. , Handling becomes worse. On the contrary, if the curing temperature is higher than 300 ° C., the resin is easily decomposed and carbonized and the energy consumption increases, which is not preferable. As the thermosetting resin having a curing temperature of from room temperature to 300 ° C. or lower, various conventionally known resins can be used. Such materials include polyester resins, phenol resins, resorcinol resins, xylene resins, amino resins, polyurethanes, unsaturated polyester resins, epoxy resins and the like.

The A layer provided on the metal sheet in the present invention is a layer that firmly bonds the metal sheet and the B layer described later, and the tensile shear strength is 10 MPa or more and 100 MPa or less at both normal temperature and high temperature (120 ° C.). A resin layer is preferred. If it is less than 10 MPa, the strength as a structure produced by heat-curing after parts processing and attachment is lowered, which is not preferable. Furthermore, in the thermosetting resin used for this A layer, it is preferable that the glass transition temperature (Tg) after the curing is 120 ° C. or higher and 300 ° C. or lower. Heat resistance is poor at temperatures below 120 ° C. In particular, in-vehicle air conditioners cannot withstand use in summer when the outside temperature is high or in southern countries where the average temperature is high, and heat resistance is sufficiently satisfactory at temperatures above 300 ° C. However, it is not preferable because the toughness of the resin is lost and the resin becomes brittle and the shear strength decreases. In addition, in the thermosetting resin used for the A layer of the present invention, the elastic modulus at 80 ° C. after the curing is preferably 1 × 10 ⁸ Pa or more and 1 × 10 ¹⁰ Pa or less. If it is less than 1 × 10 ⁸ Pa, the resin is soft and the adhesive layer tends to cohesively break. On the other hand, if it exceeds 1 × 10 ¹⁰ Pa, the toughness is lost and the adhesive layer becomes brittle.

  In the present invention, it is particularly preferable to use an epoxy resin as the thermosetting resin of the A layer. As the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, cyclic type are well known. There are aliphatic epoxy resins and special polyfunctional epoxy resins, and these can be used alone or in combination.

  A conventionally well-known thing is used as a hardening | curing agent of an epoxy resin, and there is no restriction | limiting in particular. Examples of conventionally known compounds include amine-based curing agents such as ordinary lower amines, aliphatic polyamines, aromatic polyamines, heterocyclic polyamines, polyamide amines, dicyandiamide and derivatives thereof, and imidazole compounds, and carboxylic acid anhydrides. A Lewis acid complex compound etc. other than a system hardening agent are mentioned. The use ratio of the curing agent is 2 to 30 parts by mass, preferably 3 to 20 parts by mass, per 100 parts by mass of the epoxy resin.

  Furthermore, a curing accelerator for epoxy resin can be added for epoxy resin. As the curing accelerator for epoxy resin, various conventionally known ones can be used as long as they do not substantially react with the epoxy compound at room temperature. Examples of such a curing accelerator include triphenylphosphine, tin octylate, dicyandiamide, boron trichloride / tertiary amine complex, boron trifluoride / amine complex, nitrogen-containing compounds such as imidazole and tertiary amine. The fine powdery substance etc. which modified | denatured and formed the inactive film | membrane on the surface are mentioned. The mixing ratio of the epoxy resin curing accelerator is not particularly limited, but is generally 0.01 to 5 parts by mass, preferably 0.02 to 3 parts by mass with respect to 100 parts by mass of the epoxy resin.

  Furthermore, the epoxy resin has, as auxiliary components, for example, fillers such as silica, alumina, aluminum hydroxide, calcium carbonate, titanium oxide, mica and talc, pigments, dyes, silane coupling agents, and flexibility. An appropriate amount of an agent and an antifoaming agent can be added.

  In the present invention, a multilayer adhesive sheet can be obtained by providing a thermosetting resin layer (B layer) having physical properties different from those of the A layer on the A layer. This B layer is preferably a resin layer having a gap filling property of 5 mm or more and 60 mm or less particularly at a thickness of 10 to 100 μm. The gap filling property referred to here is a length representing the ability to fill a gap having a contact formed using the rectangular test piece shown in FIG. When parts are processed, stacked in multiple layers, and then heat-cured, the resin is not sufficiently filled into the narrow gaps of the curved part, causing floating and insufficient adhesive strength at the curved part Become. On the other hand, if it exceeds 60 mm, the resin layer of the B layer is too easy to flow at the time of heat curing, causing the resin to flow out, making it difficult to stably laminate, and the workability is remarkably lowered. In addition, the specific evaluation (measurement) method of the gap filling characteristics will be described in detail in examples described later.

  In the present invention, the surface of the B layer is desirably tack-free at room temperature. B is the outermost layer of the multilayer adhesive sheet when the sheet is rolled up in the production of the multilayer adhesive sheet, when it is stored for a long time in the wound state, or when parts are processed and attached thereafter. The layers will be in contact with each other, but by making it tack-free at room temperature, the contacted B layers can be prevented from sticking to each other, and alignment can be difficult. This B layer can also be prevented from adhering to the mold.

  B layer is a layer combining the thermosetting resin and the curing agent described above, a curing accelerator used as desired, and other additives, provided on the A layer provided on the metal sheet, In the embodiment of the present invention, the obtained multilayer adhesive sheet has a maximum strength of 20 N / 25 mm or more according to the peel test. Since the peel strength is a physical property obtained when a multilayer adhesive sheet is obtained, the peel strength may be appropriately determined according to the A layer. However, as described above, the gap when the B layer has a thickness of 10 to 100 μm. It is preferable to adjust so that the resin layer has a filling property of 5 mm or more and 60 mm or less.

  When the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer is contained in this B layer, the peel strength of the multilayer adhesive sheet is adjusted to 20 N / 25 mm or more, particularly 100 N / 25 mm or more, It becomes easy to adjust the tensile stress to 40 MPa or more, particularly 50 MPa or more, and as a result, it is possible to prevent the occurrence of cracks (breakage or breakage) in the B layer, thereby obtaining a highly reliable product (for example, a heat exchanger). This is preferable.

  Such a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer is a dicarboxylic acid component having a phenolic hydroxyl group, such as 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyphthalic acid, 3- Hydroxyphthalic acid, 2-hydroxyterephthalic acid, and dicarboxylic acids having no phenolic hydroxyl group include phthalic acid, isophthalic acid, terephthalic acid, dicarboxyl naphthalene, succinic acid, fumaric acid, glutaric acid, adipic acid, 1,3- For cyclohexanedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 3,3′-methylenedibenzoic acid, etc., diamines such as 3,3′-diamine-4,4′-dihydroxyphenylmethane, 2,2 -Bis (3-amino-4-hydroxyphen L) Hexafluoropropane, 2,2-bis (3-amino-4-hydroxyphenyl) difluoromethane, 3,4-diamino-1,5-benzenediol, 3,3'-dihydroxy-4,4'-diaminobis Phenyl, 3,3′-diamino-4,4′-dihydroxybiphenyl, 2,2-bis (3-amino-4-hydroxyphenyl) ketone, 2,2-bis (3-amino-4-hydroxyphenyl) sulfide 2,2-bis (3-amino-4-hydroxyphenyl) ether, 2,2-bis (3-amino-4-hydroxyphenyl) sulfone, 2,2-bis (3-amino-4-hydroxyphenyl) Propane, 2,2-bis (3-hydroxy-4-aminophenyl) propane, 2,2-bis (3-hydroxy-4-aminophenyl) methane, etc. Diamines containing no phenolic hydroxyl groups include 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, diaminonaphthalene, piperazine, hexanetylenediamine, tetramethylenediamine, and m-xylene. Diamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminobenzophenone, 2,2′-bis (4-aminophenyl) propane, 3,3′-diaminodiphenylsulfone, 3,3′-diaminodiphenyl, etc. In addition, these are heated and stirred under an inert atmosphere such as nitrogen in an organic solvent represented by N-methyl-2-pyrrolidone using a condensing agent in the presence of a phosphite ester and a pyridine derivative, for example. , Containing a phenolic hydroxyl group by performing a condensation reaction It is obtained by forming a polyamide-polybutadiene-acrylonitrile copolymer. Among them, it is preferable to use a copolymer represented by the following formula (1).

（式中、ｘ、ｙ、ｚ、ｌ、ｍ及びｎは、それぞれ平均重合度であって、ｘ＝３〜７、ｙ＝１〜４、ｚ＝５〜１５、ｌ＋ｍ＝２〜２００の整数をそれぞれ示し、ｍ／（ｌ＋ｍ）≧０．０４である。）

(Wherein, x, y, z, l, m and n are average polymerization degrees, and x = 3 to 7, y = 1 to 4, z = 5 to 15, and l + m = 2 to 200 integers. And m / (l + m) ≧ 0.04.)

  This B layer is a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer, the same thermosetting resin as in the case of the A layer, particularly an epoxy resin and a curing agent, and a cured epoxy resin used as required. It is comprised from the resin composition containing an accelerator. The blending ratio of the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer is preferably in the range of 1 to 10 parts by mass with respect to 100 parts by mass of the epoxy resin. When the blending amount of the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer is less than this range, it is disadvantageous in terms of adjusting the tensile stress and peel strength as a multilayer adhesive sheet. For example, a multilayer adhesive sheet is used. When a heat exchanger is manufactured, it becomes difficult to obtain a sufficiently reliable heat exchanger, and when the blending amount of the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer exceeds this range, Since filling property falls, it is not preferable. The blending ratio of the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer is particularly preferably 1 to 5 parts by weight, and more preferably 2.5 to 2.5 parts, in terms of tensile stress and peel strength controllability and gap filling properties. 3.5 parts by mass. When the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer is included in both the A layer and the B layer, the blending ratio of the B layer is preferably smaller than the blending ratio of the A layer.

  A preferred embodiment of the multilayer adhesive sheet of the present invention is one in which thermosetting resins having different functions are provided as an A layer and a B layer on at least one surface of a metal sheet 1 as a core material, as shown in FIG. . When manufacturing a heat exchanger by processing and assembling parts using a multilayer adhesive sheet and then heat-curing it, in order to have sufficient adhesive strength even in the curved part of the laminated structure, tensile shear is required. It is important to sufficiently fill the gaps between the curved portions with a high-strength thermosetting resin. However, in the structure in which only one layer of the thermosetting resin is provided on the metal sheet as the core material, if the tensile shear strength is increased, the gap filling property is lowered, and conversely, the gap filling property is increased. Tensile shear strength decreases. That is, the tensile shear strength and the gap filling property are contradictory.

  Therefore, conventionally, by laminating these thermosetting resin layers having contradictory properties as the A layer and the B layer, both properties are satisfied, and a thermosetting resin having a high tensile shear strength is placed in the gaps between the curved portions. Although it was possible to sufficiently fill (see Patent Document 3), the B layer has a lower resin strength after curing than the A layer. Therefore, when the B layers are bonded and cured together, A crack (damaged or broken) occurs in the layer, and a crack (damaged or broken) also occurs in the A layer. As a result, the layer may peel near the interface between the metal sheet and the A layer. That is, the gap filling property of the B layer and the strength at the time of curing are contradictory properties.

  In the present invention, this point is improved, and the tensile stress in the tensile test of the B layer which is the outermost layer is 40 MPa or more, preferably 50 MPa, thereby improving the strength after curing of the B layer. It was possible to obtain a multilayer adhesive sheet in which no delamination or layer destruction occurred between the metal sheet and the A layer, inside the A layer, between the A layer and the B layer, and inside the B layer.

  The thickness of the A layer and the B layer can be arbitrarily determined, but the total thickness of them combined is preferably 10 μm or more and 200 μm or less, from the viewpoint of cost reduction due to reduction in the amount used, 15 μm or more, More preferably, it is 150 μm or less. Within that range, the ratio of the thicknesses of the A layer and the B layer can be changed in consideration of the balance between the required tensile shear strength and gap filling property. In other words, when the degree of bending is moderate and the tensile shear strength is important, the thickness ratio of layer A is increased, and conversely, the degree of bending is large and the gap is in a complicated shape. Therefore, it is possible to increase the ratio of the thickness of the B layer with an emphasis on gap filling properties. Generally, the ratio of the thickness of the B layer to the A layer (B / A) is preferably 0.5 or more and 20 or less.

  Next, an example of the manufacturing method of the multilayer adhesive sheet having the configuration shown in FIG. 2 according to the present invention will be described. This is a multilayer adhesive sheet having a structure in which an A layer and a B layer are laminated on both surfaces of a metal sheet, but other configurations can be manufactured by the same method.

  An A layer forming coating liquid composed of a thermosetting resin composition for A layer and a B layer forming coating liquid composed of a thermosetting resin composition for B layer are prepared by the following procedure. First, using a roll coater, a comma coater, a bar coater or the like, the A layer forming coating solution is applied to one side of the metal sheet so as to have a desired coating thickness. This is heat-treated at 80 to 120 ° C. for 1 to 5 minutes through a dryer, and the solvent in the thermosetting resin composition is removed and dried to form the A layer. Next, a layer A is formed on the opposite surface in the same manner to produce a double-side coated product. Next, on each A layer, a B layer forming coating solution is applied and dried in the same manner as in the case of the A layer, and both sides of the metal sheet have thermosetting resins of the A and B layers. A multilayer adhesive sheet having the structure is prepared.

<Preparation of coating solution>
(1) Add a filler made of an inorganic filler, a flexibility-imparting agent made of an elastomer, and a silane coupling agent to a resin solution that has been diluted with a solvent so that the epoxy resin has a desired viscosity in advance. To do.
(2) A curing agent and a curing accelerator are added to the liquid of (1) and further mixed.

  The multilayer adhesive sheet of the present invention is formed by molding parts of a predetermined size and shape from the sheet by pressing or the like, and laminating and assembling the parts together and heating them to the melting temperature of the A layer and the B layer to bond them. Used as such. In the multilayer adhesive sheet of the present invention, when the shape of the component is complicated, the multilayer adhesive sheet must be curved and laminated. However, even if such a thin gap is generated, the adhesive flows. By filling, even a curved portion can be bonded without causing floating.

  The multilayer adhesive sheet of the present invention is advantageously used as a material for forming a heat exchanger. FIG. 3 schematically shows a part of a cross section of one embodiment of a heat exchanger formed of the multilayer adhesive sheet of the present invention. In FIG. 3, 11 shows a heat exchanger, 12 and 13 show the multilayer adhesive sheet of this invention. The narrower space portion X having a mountain shape is a portion through which liquids such as refrigerant oil, water, and LLC flow, and the other wider space portion Y is a portion through which air flows.

  In order to perform heat exchange between two fluids (liquid and gas) using this heat exchanger, the liquid and air are made to exchange via the multilayer adhesive sheet of the present invention as shown in FIG.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. The physical properties of the multilayer adhesive sheet were evaluated according to the following methods.

[Maximum peel strength]
On one side of the metal sheet (aluminum plate), the A layer forming coating solution is applied with a bar coater so that the thickness after drying becomes a predetermined thickness, put in a hot air dryer, and heated and dried at 100 ° C. for 3 minutes. A layer was formed. Next, on the A layer, the B layer forming coating solution is applied and dried in the same manner as in the case of the A layer so that the thickness after drying becomes a predetermined thickness, and a B layer is formed, for measuring peel strength. A multilayer adhesive sheet sample was prepared. Next, the sample thus prepared was processed into the shape and size of a test piece in accordance with JIS K 6854, and the multilayer adhesive sheets were stacked so that the surfaces of the outermost thermosetting resin layer (B layer) face each other. In a state of being sandwiched between 1.5 mm aluminum plates and tightened with a pinch cock, they were placed in a hot air dryer and cured by heating at 200 ° C. for 30 minutes. Using the test piece for the peel test produced in this way, measurement was performed under the condition of a test speed of 20 mm / min in accordance with JIS K 6854, and the maximum value was measured from immediately after the start of measurement until the end of measurement. This was determined as the maximum peel strength.

[Tensile stress of layer B]
A test piece based on ASTM D-638 Type I was prepared from the B layer forming coating solution.
Next, using this test piece, tensile stress was measured in accordance with JIS K 7113 at a test speed of 5 mm / min.

[Gap filling characteristics]
As shown in FIG. 2, one multilayer adhesive sheet sample S2 (thickness: 1.0 mm, width: 25 mm, length: 60 mm) produced by the same method as the peel strength measurement sample was placed horizontally, and an aluminum plate S1 (thickness) (1.0 mm in length, 25 mm in width, 55 mm in length) were placed vertically, one side of the aluminum plate S1 was brought into contact with the multilayer adhesive sheet sample S2, and a spacer rod (diameter 1.5 mm) was interposed on the other side and assembled. Then, it heated for 30 minutes at the curing temperature of 200 degreeC, and made both adhere | attach. After bonding and heating, the length in the sample longitudinal direction (gap filling length) of the adhesive melted and fluidly filled in the gap between the aluminum plate S1 and the multilayer adhesive sheet sample S2 was measured to obtain gap filling characteristics.

[B layer surface tackiness]
The tackiness of the surface of layer B was evaluated according to the following criteria by finger touch.
○: No tack.
X: There is tack.

Example 1
[Preparation of A layer forming coating solution]
Phenolic dicyclopentadiene type epoxy resin (Dainippon Ink Chemical Co., Ltd., trade name: HP7200-L) (solid content 70% toluene solution product) 71.4 parts by mass, bisphenol A type epoxy resin (Japan epoxy) 50.0 parts by mass of Resin Co., Ltd., trade name: Epicoat 828) was mixed with stirring and dissolved to prepare an epoxy resin solution. Next, as a flexibility imparting agent, a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer (manufactured by Nippon Kayaku Co., Ltd., trade name: BP-40D) (solid content 40% DMF solution) Product) 125.0 parts by mass, titanium oxide (made by Ishihara Sangyo Co., Ltd., trade name: Typek R-580) as a filler, 100.0 parts by mass, silane coupling agent (produced by Chisso Corporation, trade name: Sila Ace) S-510) 1.0 part by mass was added and mixed with a homogenizer. Further thereafter, 5.9 parts by mass of a curing agent (trade name: Epicure DICY15, manufactured by Japan Epoxy Resin Co., Ltd.) and 0.5 parts by mass of triphenylphosphine as a curing accelerator were added, and the thermosetting property of the A layer was added. A layer formation coating liquid consisting of a resin composition was prepared.

[Preparation of B layer forming coating solution]
Next, phenol dicyclopentadiene type epoxy resin (manufactured by Dainippon Ink & Chemicals, Inc., trade name: HP7200-L) (solid content 70% toluene solution product) 142.9 parts by mass, a curing agent (Japan epoxy Resin Co., Ltd., trade name: Epicure DICY15) 5.2 parts by mass, curing agent 0.5 parts by mass of triphenylphosphine, phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer (Nippon Kayaku ( Co., Ltd., trade name: BP-40D) (solid content 40% DMF solution product) 12.5 parts by mass, mixed with a homogenizer, and coated with a thermosetting resin composition for layer B Was prepared.

[Production of multilayer adhesive sheet]
The A layer forming coating solution was applied to one side of an aluminum plate having a thickness of 100 μm and dried (100 ° C., 3 minutes) to provide an A layer having a thickness of 5 μm. Next, an A layer having a film thickness of 5 μm was provided on the opposite surface in the same manner. Subsequently, the B layer forming coating solution was applied onto the A layer provided as described above and dried (100 ° C., 3 minutes) to provide a B layer having a thickness of 25 μm. Next, a B layer having a film thickness of 25 μm was provided on the opposite surface in the same manner, and thus a multilayer adhesive sheet having two thermosetting resin layers having different functions according to the present invention on both sides was produced. The physical properties of this product are shown in Table 1.

Example 2
In Example 1, phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer (manufactured by Nippon Kayaku Co., Ltd., trade name: BP-40D) used in the B layer forming coating solution (solid content 40% DMF solution) A multilayer adhesive sheet was prepared in the same manner as in Example 1 except that the product was 7.5 parts by mass. The physical properties of this product are shown in Table 1.

Example 3
In Example 1, phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer (manufactured by Nippon Kayaku Co., Ltd., trade name: BP-40D) used in the B layer forming coating solution (solid content 40% DMF solution) A multilayer adhesive sheet was prepared in the same manner as in Example 1 except that the product was 2.5 parts by mass. The physical properties of this product are shown in Table 1.

Example 4
In Example 1, a multilayer adhesive sheet was produced in the same manner as in Example 1 except that the thickness of the B layer was 75 μm. The physical properties of this product are shown in Table 1.

Example 5
In Example 2, a multilayer adhesive sheet was produced in the same manner as in Example 2 except that the thickness of the B layer was 75 μm. The physical properties of this product are shown in Table 1.

Example 6
In Example 3, a multilayer adhesive sheet was produced in the same manner as in Example 3 except that the thickness of the B layer was 75 μm. The physical properties of this product are shown in Table 1.

Comparative Example 1
In Example 1, a multilayer adhesive sheet was produced in the same manner as in Example 1 except that the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer was not used as the B layer forming coating solution. The physical properties of this product are shown in Table 1.

Comparative Example 2
In Comparative Example 1, a multilayer adhesive sheet was produced in the same manner as Comparative Example 1 except that the thickness of the B layer was 30 μm and the A layer was not provided. The physical properties of this product are shown in Table 1.

Comparative Example 3
In Comparative Example 1, a multilayer adhesive sheet was prepared in the same manner as Comparative Example 1 except that the thickness of the A layer was 30 μm and the B layer was not provided. The physical properties of this product are shown in Table 1.

Comparative Example 4
In Example 4, a multilayer adhesive sheet was produced in the same manner as in Example 4 except that the phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer was not used as the B layer forming coating solution. The physical properties of this product are shown in Table 1.

  From Table 1, the multilayer adhesive sheets (Examples 1 to 6) of the present invention have higher peel maximum strength and tensile stress than those of Comparative Examples 1 to 4, and well-balanced adhesive properties that also have good gap filling properties. It can be seen that Furthermore, since the thing of Examples 4-6 is excellent in a gap filling characteristic, when producing a heat exchanger using this multilayer adhesive sheet, it is anticipated that a highly reliable heat exchanger will be obtained. .

  The present invention can be suitably used for production of a lightweight and high-strength heat exchanger.

It is explanatory drawing which shows the measuring method of the gap filling characteristic of the multilayer adhesive sheet of this invention. It is explanatory drawing which shows an example of a structure of the multilayer adhesive sheet of this invention. It is a schematic diagram which shows an example of the heat exchanger formed using the multilayer adhesive sheet of this invention.

Explanation of symbols

1: Core material A: A layer B: B layer S1: Aluminum plate S2: Multi-layer adhesive sheet Sample 11: Heat exchanger

Claims (10)

  A multilayer adhesive sheet having a thermosetting resin layer A and a thermosetting resin layer B having different functions on at least one side of the metal sheet, the layer B on the layer A, and the layer B A multilayer adhesive sheet, wherein the layer contains a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer. A multilayer adhesive sheet having a thermosetting resin layer A and a thermosetting resin layer B having different functions on at least one surface of the metal sheet, the layer B on the layer A, and the following peeling A multilayer adhesive sheet having a maximum strength of T-type peeling by a test of 20 N / 25 mm or more.
Peel test:
The multilayer adhesive sheet having the laminated structure is processed into the shape and size of a test piece based on JIS K 6854. The multilayer adhesive sheets thus processed are overlapped so that the surfaces of the thermosetting resin layer of the B layer face each other, sandwiched between 1.5 mm aluminum plates and clamped with a pinch cock, and placed in a hot air dryer at 200 ° C. And cured for 30 minutes to obtain a test piece for a peel test. Using this test piece, the peel strength was measured in accordance with JIS K 6854 at a test speed of 20 mm / min, and the maximum value was obtained from the measured values immediately after the start of measurement until the end of the measurement. And A multilayer adhesive sheet having a thermosetting resin layer A and a thermosetting resin layer B having different functions on at least one surface of the metal sheet, and the tensile stress of the layer B according to the following tensile test is 40 MPa or more. Multi-layer adhesive sheet.
Tensile test:
A test piece based on ASTM D-638 Type I is prepared from the material forming the B layer, and this is used as a test piece for a tensile test. Using this test piece, tensile stress is measured under the condition of a test speed of 5 mm / min according to JIS K7113.   The multilayer adhesive sheet according to claim 2, wherein the thermosetting resin is an epoxy thermosetting resin.   The multilayer adhesive sheet according to claim 4, wherein the layer B contains a phenolic hydroxyl group-containing aromatic polyamide-polybutadiene-acrylonitrile copolymer.   A layer made of a thermosetting resin having a tensile shear strength of 10 MPa or more and 100 MPa or less, and a gap filling characteristic when the thickness is 10 to 100 μm formed above the A layer is 5 mm or more and 60 mm or less The multilayer adhesive sheet according to any one of claims 1 to 5, having a B layer made of a thermosetting resin.   The multilayer adhesive sheet according to any one of claims 1 to 6, wherein the metal sheet is made of an aluminum material.   A heat exchanger forming material comprising the multilayer adhesive sheet according to any one of claims 1 to 7.   The manufacturing method of the heat exchanger which forms a heat exchanger by carrying out the adhesion process of the heat exchanger formation material of Claim 8.   A heat exchanger formed by bonding the heat exchanger forming material according to claim 8.

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