Method for manufacturing laminate

Abstract

The present invention addresses the problem of providing a method for producing a laminate, said method being capable of producing a laminate in which an adherend is adhered to a cured product having a high elastic modulus in a high-temperature environment, even when the laminate is cured at a low temperature for a short period of time. This problem is solved by a method for producing a laminate, the method comprising: a step in which a curable resin composition having a specific composition is applied to a first body to be bonded, and the first body to be bonded is bonded to a second body to be bonded; and a step for curing the curable resin composition at a low temperature, in which the ratio of the thickness of the cured product in the laminate to the average thickness of the adherend is within a specific range.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing a laminate. BACKGROUND

[0002] Curing resin compositions containing an epoxy resin are excellent in dimensional stability, mechanical strength, electrical insulation properties, heat resistance, water resistance, chemical resistance, and the like, and are being utilized for various uses.

[0003] As an example of the use of the curing resin composition containing an epoxy resin like this, a structural adhesive for automobiles is known. Patent Documents 1 and 2 disclose technologies related to the curing resin composition containing an epoxy resin.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Laid-Open Patent Publication No. 2019-038926

[0007] Patent Document 2: International Publication WO 2018 / 156450 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, as with the conventional curing resin compositions described in Patent Documents 1 and 2, when an adherend is adhered using the curing resin composition, in the case where the curing resin composition is cured at a low temperature and for a short time, there is a problem that the elastic modulus of the cured product, particularly the elastic modulus at high temperatures, greatly decreases in the obtained laminate.

[0010] In view of the current situation as described above, an object of the present application is to provide a laminate in which an adherend is adhered by a cured product having a high elastic modulus at high temperatures, even in the case where curing is performed under conditions of a low temperature and for a short time.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] In order to solve the above problems, the present inventors and others have conducted intensive research, as a result of which the present application has been completed.

[0013] That is, one embodiment of the present application relates to a method for manufacturing a laminate obtained by sequentially laminating a first adherend, a cured product of a curable resin composition, and a second adherend, the method for manufacturing a laminate comprising: a step (i) (adhesion step) of applying the curable resin composition to the first adherend and adhering the second adherend to the first adherend, a step (ii) (curing step) of curing the curable resin composition, the curable resin composition containing an epoxy resin (A) and 3.5 parts by mass to 19.0 parts by mass of dicyandiamide (B) per 100 parts by mass of the epoxy resin (A), the epoxy resin (A) containing 51% by mass to 100% by mass of unmodified bisphenol A-type epoxy resin (A-1) in 100% by mass of the total amount of the epoxy resin (A), the curing temperature of the curable resin composition in the step (ii) being 105°C to 145°C, the curing time of the curable resin composition in the step (ii) being 10 minutes to 60 minutes, and the ratio (Y / X) of the thickness (Y) of the cured product to the average thickness (X) of the first adherend and the second adherend being 0.5 to 10.0.

[0014] Effects of the Invention

[0015] According to one embodiment of the present application, even in the case where curing is performed under low temperature and short time conditions, a laminate in which adherends are adhered by a cured product having a high elastic modulus under a high temperature environment can be provided. DETAILED DESCRIPTION

[0016] One embodiment of the present application will be described below, but the present application is not limited thereto. The present application is not limited to each aspect described below, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining respective disclosed technical means in different embodiments and examples are also included in the technical scope of the present application. In addition, academic and patent literatures described in this specification are all cited as references in this specification. In addition, in this specification, "A to B" indicating a numerical range means "A or more and B or less" unless otherwise specifically marked.

[0017] 〔1. Technical idea of the present application〕

[0018] In recent years, from the viewpoint of coping with the trend of carbon neutrality, low-temperature baking of an oven for electrodeposition coating (a rust-preventive base paint for automobiles) is required, and the baking temperature at the time of electrodeposition coating of 170 to 190°C in the past is lowered to about 120 to 145°C. In addition, shortening of the baking time (within 60 minutes) is also required.

[0019] In the manufacturing process of an automobile, generally, an automobile structural adhesive is cured in the above-mentioned oven at the same time as an electrodeposition paint. Therefore, for the structural adhesive, it is necessary to perform curing under low temperature (below 145°C) and short time.

[0020] Further, for the automobile structural adhesive, it is necessary to have a high elastic modulus not only in a normal environment (for example, at room temperature) but also in a high temperature environment such as in summer.

[0021] However, as described in Patent Literatures 1 and 2, for the conventional curable resin composition, it has been found that in the case where the curable resin composition is cured under low temperature and short time, there is a problem that the Tg of the obtained cured product is low. Further, as a result, it has been found that the cured product obtained by bonding adherends using the curable resin composition and a laminate including the cured product have a low elastic modulus in a high temperature environment.

[0022] Under the above-mentioned circumstances, the present inventors have conducted intensive studies with the aim of providing a laminate in which adherends are bonded by a cured product having a high elastic modulus in a high temperature environment even if the cured product is cured under low temperature and short time. In the studies, the present inventors have obtained the following new insight that there is a correlation between the ratio (Y / X) of the thickness (Y) of a cured product obtained by curing a specific curable resin composition under low temperature and short time to the average thickness (X) of adherends bonded by the cured product and the glass transition temperature (hereinafter, sometimes referred to as "Tg") of the cured product. Based on this new insight, further intensive studies have been conducted, and as a result, the present inventors have found that by (1) using a curable resin composition having a specific composition, and (2) controlling the ratio (Y / X) of the thickness (Y) of a cured product obtained by curing the curable resin composition to the average thickness (X) of adherends bonded by the cured product within a specific range, a laminate in which adherends are bonded by a cured product having a high elastic modulus in a high temperature environment can be provided even if the cured product is cured under low temperature and short time, thereby completing the present application.

[0023] The technology of bonding (lamination) adherends by a cured product having a high elastic modulus in a high temperature environment even if the cured product is cured under low temperature and short time can be considered as a surprising finding that has not been known in the past. Further, the manufacturing method of such a laminate is particularly useful in the manufacturing of a vehicle body structure of an automobile.

[0024] 〔2. Manufacturing method of laminate〕

[0025] The manufacturing method of the laminate of one embodiment of the present application is a manufacturing method of a laminate in which a first adherend, a cured product of a curable resin composition, and a second adherend are laminated in this order, the method including: a process (i) (adhesion process) of applying the curable resin composition to the first adherend and adhering the second adherend to the first adherend; and a process (ii) (curing process) of curing the curable resin composition, wherein the curable resin composition includes an epoxy resin (A) and 3.5 parts by mass to 19.0 parts by mass of dicyandiamide (B) relative to 100 parts by mass of the epoxy resin (A), the epoxy resin (A) includes 51 % by mass to 100 % by mass of unmodified bisphenol A-type epoxy resin (A-1), the curing temperature of the curable resin composition in the process (ii) is 105 °C to 145 °C, the curing time of the curable resin composition in the process (ii) is 10 minutes to 60 minutes, and the ratio (Y / X) of the thickness (Y) of the cured product of the curable resin composition to the average thickness (X) of the first adherend and the second adherend is 0.5 to 10.0. Hereinafter, the manufacturing method of the laminate of one embodiment of the present application is sometimes referred to as "the present manufacturing method", the epoxy resin (A) is sometimes referred to as "component (A)", and the dicyandiamide (B) is sometimes referred to as "component (B)".

[0026] According to the present manufacturing method, a laminate in which adherends are adhered with a cured product having a high elastic modulus in a high-temperature environment can be provided even when curing is performed at a low temperature and for a short time.

[0027] (2-1. Curable resin composition)

[0028] Hereinafter, the curable resin composition used in the present manufacturing method will be described in detail. The curable resin composition of one embodiment of the present application (hereinafter, sometimes referred to as "the present curable resin composition") includes 3.5 parts by mass to 19.0 parts by mass of component (B) relative to 100 parts by mass of component (A). The cured product can be obtained by curing the present curable resin composition by the method described in the curing process below.

[0029] Hereinafter, each component that the present curable resin composition can include will be described in detail.

[0030]

[0031] ​In the present specification, an epoxy resin refers to a resin having at least one epoxy group in the molecule, preferably having two or more epoxy groups. As the epoxy resin that can be contained in the present curable resin composition as component (A), mention can be made of unmodified bisphenol A type epoxy resin (A-1) (hereinafter, sometimes referred to as "component (A-1)"), unmodified bisphenol F type epoxy resin (A-2) (hereinafter, sometimes referred to as "component (A-2)"), aliphatic polybasic acid-modified epoxy resin (A-3) (hereinafter, sometimes referred to as "component (A-3)"), and others (epoxy resins other than component (A-1) to component (A-3)). In the present specification, component (A) refers to the total of these epoxy resins contained in the present curable resin composition. For example, in the present specification, the amount of component (A) refers to the total amount of component (A-1), component (A-2), component (A-3), and other epoxy resins contained in the present curable resin composition. Component (A) can also be referred to as a curable resin.

[0032] The content of component (A) in the present curable resin composition is not particularly limited, and is preferably 20 to 80 mass%, more preferably 25 to 75 mass%, and further preferably 35 to 55 mass%, in 100 mass% of the total amount of the present curable resin composition. If the content of component (A) in the present curable resin composition is 20 mass% or more, there is an advantage that the strength and the adhesive strength of the obtained cured product are excellent, and if it is 80 mass% or less, there is an advantage that the processability of the curable resin composition is excellent.

[0033] (unmodified bisphenol A type epoxy resin (A-1))

[0034] In 100 mass% of the total amount of component (A), component (A) contains component (A-1) at 51 to 100 mass%. In 100 mass% of the total amount of component (A), the content of component (A-1) in component (A) is 51 to 100 mass%, preferably 55 to 90 mass%, and more preferably 60 to 80 mass%. By making the content of component (A-1) in component (A) contained in the present curable resin composition within the above range, a cured product excellent in elastic modulus under a high temperature environment can be provided. The epoxy equivalent of component (A-1) is not particularly limited, and is preferably 150 to 1000, more preferably 160 to 500, and further preferably 170 to 200. If the epoxy equivalent of component (A-1) is 150 or more, there is a tendency to improve the adhesive strength and the rigidity under a high temperature of the obtained cured product, and if it is 1000 or less, there is a tendency to improve the handleability of the curable resin composition.

[0035] In the present specification, the epoxy equivalent weight refers to the molecular weight of each epoxy group contained in a compound having an epoxy group, and specifically, is a value calculated based on the following formula:

[0036] Epoxy equivalent weight (g / eq) = Weight average molecular weight (Mw) of the compound / Number of epoxy groups per molecule of the compound (average).

[0037] Note that the epoxy equivalent weight can be measured according to JIS K7236.

[0038] As examples of the commercially available component (A-1), there can be mentioned, for example, products marketed by Mitsubishi Chemical Corporation under the trade name jER (e.g., jER828, jER825, jER827, jER828EL, jER828US, jER828XA, jER834, jER1001, jER1002, jER1004, jER1007, jER1009, jER1010); products marketed by Momentive Specialty Chemicals, Inc. under the trade name EPON (e.g., EPON 1510, EPON 1310, EPON 828, EPON 872, EPON 1001, EPON 1004, EPON 2004); products marketed by Olin Epoxy Co. under the trade name DER (e.g., DER 331, DER 332, DER 336, and DER 439); products marketed by ADEKA Corporation under the trade name ADEKA RESIN (e.g., EP-4100, EP-4300, EP-4400, EP-4530, EP-4504); and products marketed by DIC Corporation under the trade name EPICLON (e.g., EPICLON 840, EPICLON 850), and the like, but are not limited to these.

[0039] (Unmodified bisphenol F type epoxy resin (A-2))

[0040] The component (A) can contain the component (A-2) in addition to the component (A-1). In the case where the curable resin composition contains the component (A-2) as the component (A), the content of the component (A-2) in the component (A) is preferably 1 to 80 mass%, more preferably 5 to 50 mass%, and further preferably 10 to 30 mass% in the total amount of 100 mass% of the component (A). The component (A) contained in the curable resin composition can provide a curable resin composition which is low in viscosity and excellent in processability, and which is excellent in toughness and adhesive strength of the obtained cured product, by containing the component (A-2) within the above range.

[0041] The epoxy equivalent weight of component (A-2) is not particularly limited, and is preferably 150 to 1000, more preferably 160 to 500, further preferably 170 to 200. If the epoxy equivalent weight of component (A-2) is 150 or greater, this has the advantage that the adhesion strength and rigidity at high temperatures of the obtained cured product are excellent, and if it is 1000 or less, the handleability of the curable resin composition is improved, and thus is preferred.

[0042] As examples of commercially available component (A-2), products sold by Mitsubishi Chemical Corporation under the trade name jER (for example, jER 806, jER 806H, jER 807, jER 4005P, jER 4007P, jER 4010P), products sold by Olin Epoxy Co. under the trade name DER (for example, DER 334), products sold by ADEKA Corporation under the trade name ADEKA RESIN (for example, EP-4901, EP-4901E), and products sold by DIC Corporation under the trade name EPICLON (for example, EPICLON 830), and the like can be given, but are not limited to these.

[0043] (aliphatic polybasic acid-modified epoxy resin (A-3))

[0044] The curable resin composition of the present application can contain component (A-3) as component (A). In the case where the curable resin composition of the present application contains component (A-3) as component (A), the content of component (A-3) in component (A) is preferably more than 0 mass% and less than 3.0 mass%, more preferably more than 0 mass% and 2.0 mass% or less, further preferably more than 0 mass% and 1.0 mass% or less, in 100 mass% of component (A). The content of component (A-3) in component (A) can be 0 mass%. In other words, the curable resin composition of the present application can not contain component (A-3) as component (A). Since a curable resin composition that is more excellent in the elastic modulus at high temperature of the obtained cured product can be provided, the curable resin composition of the present application is preferably (1) does not contain component (A-3) as component (A); or (2) contains more than 0 mass% and less than 3.0 mass% of component (A-3) as component (A), in 100 mass% of component (A).

[0045] In the present specification, an aliphatic polybasic acid-modified epoxy resin refers to a compound obtained by addition reaction of an aliphatic polybasic acid or the like with an epoxy resin.

[0046] As the aliphatic polybasic acid which undergoes an addition reaction with the above-mentioned epoxy resin, there can be mentioned, for example, an unsaturated polybasic carboxylic acid or an acid anhydride thereof which does not have an aromatic ring such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, or the like, or a saturated polybasic carboxylic acid or an acid anhydride thereof which does not have an aromatic ring such as tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, cyclohexane dicarboxylic acid, succinic acid, malonic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, dimer acid, trimer acid, or the like, but is not limited to these, and a generally used aliphatic polybasic acid can be used. From the viewpoint of excellent vibration-damping properties of the obtained cured product, a dimer acid is particularly preferable.

[0047] In the present specification, "dimer acid" means a dimer of an unsaturated aliphatic acid having 18 carbon atoms. As the above-mentioned aliphatic acid having 18 carbon atoms, there can be mentioned, for example, oleic acid, linoleic acid, linolenic acid, or the like.

[0048] As the epoxy resin which undergoes an addition reaction with the above-mentioned aliphatic polybasic acid or the like, various epoxy resins can be used. There can be exemplified, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol AD type epoxy resin, a bisphenol S type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, a phenol aldehyde type epoxy resin, a glycidyl ether type epoxy resin of a bisphenol A propylene oxide adduct, a hydrogenated bisphenol A (or F) type epoxy resin, a fluorinated epoxy resin, a flame-retardant type epoxy resin such as a glycidyl ether of tetra-bromobisphenol A, a p-hydroxybenzoic acid glycidyl ester type epoxy resin, a m-aminophenol type epoxy resin, a diaminodiphenylmethane type epoxy resin, various alicyclic epoxy resins, N,N-diglycidyl aniline, N,N-diglycidyl o-toluidine, trisglycidyl isocyanurate, divinylbenzene dioxide, resorcinol diglycidyl ether, polyalkylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, or the like, but is not limited to these, and a generally used epoxy resin can be used.

[0049] As the component (A-3), an addition reaction product of the above-mentioned various aliphatic polybasic acids and the above-mentioned epoxy resin is used without particular limitation. As a specific example of the component (A-3), there can be mentioned a dimer acid-modified epoxy resin, a hydrogenated dimer acid-modified epoxy resin, a trimer acid-modified epoxy resin, or the like. From the viewpoints of excellent availability and excellent vibration-damping properties of the obtained cured product, a dimer acid-modified epoxy resin is preferable, and it is an addition product of a dimer of tall oil fatty acid (dimer acid) and a bisphenol A type epoxy resin as described in International Publication No. 2010-098950. As the component (A-3), one of these compounds can be used alone, or two or more of them can be used in combination.

[0050] From the viewpoint of good obtainability and more excellent vibration-damping properties of the obtained cured product, component (A-3) preferably contains a dimer acid-modified epoxy resin. From the viewpoint of good obtainability and more excellent vibration-damping properties of the obtained cured product, in 100% by mass of the total amount of component (A-3), the present curable resin composition preferably contains 80% by mass or more of a dimer acid-modified epoxy resin, more preferably contains 90% by mass or more, further preferably contains 95% by mass or more, particularly preferably contains 100% by mass.

[0051] The epoxy equivalent of component (A-3) is not particularly limited, and is preferably 250 to 800, more preferably 300 to 700, further preferably 380 to 500. If the epoxy equivalent of component (A-3) is 250 or more, the obtained cured product has excellent vibration-damping properties, and if it is 800 or less, the handling properties of the curable resin composition are improved, and thus it is preferred.

[0052] (Other epoxy resins)

[0053] The present curable resin composition can contain an epoxy resin other than the above-described components (A-1) to (A-3) (other epoxy resin) as component (A). As the other epoxy resin, for example, rubber-modified epoxy resins, bisphenol AD-type epoxy resins, bisphenol S-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol aldehyde-type epoxy resins, glycidyl ether-type epoxy resins of bisphenol A propylene oxide adducts, hydrogenated bisphenol A (or F)-type epoxy resins, fluorinated epoxy resins, glycidyl ethers of tetrabromobisphenol A, and the like flame-retardant epoxy resins; p-hydroxybenzoic acid glycidyl ester-type epoxy resins, m-aminophenol-type epoxy resins, diaminodiphenylmethane-type epoxy resins, various alicyclic epoxy resins, N,N-diglycidyl aniline, N,N-diglycidyl o-toluidine, trisglycidyl isocyanurate, divinylbenzene dioxide, resorcinol diglycidyl ether, polyalkylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, diglycidyl esters of aliphatic polybasic acids, glycerol such as diglycidyl ethers of polyhydric aliphatic alcohols having two or more; epoxy compounds of chelate-modified epoxy resins, urethane-modified epoxy resins, hydantoin-type epoxy resins, petroleum resins, and the like unsaturated polymers; amino group-containing glycidyl ether resins, epoxy compounds obtained by addition reaction of the above-described epoxy resins with bisphenol A (or F) or polybasic acids, and the like can be exemplified, but are not limited thereto, and generally used epoxy resins can be used.

[0054] In the case where the present curable resin composition contains other epoxy resins as component (A), the content of the other epoxy resins in component (A) is not particularly limited, and is preferably 0.0 to 20.0 mass%, more preferably 0.1 to 10.0 mass%, further preferably 1.0 to 5.0 mass%, relative to 100 mass% of component (A).

[0055] < Dicyandiamide (B) >

[0056] The present curable resin composition contains component (B). In the present curable resin composition, the dicyandiamide as component (B) functions as a curing agent that cures the curable resin composition. The dicyandiamide does not function to cure at a temperature of at least lower than 100°C, or even if it functions to cure, the reaction proceeds very slowly. On the other hand, in the case where it is heated to a temperature of 100°C or higher, preferably 120°C, the dicyandiamide functions to cure rapidly, and the curable resin composition can be cured rapidly. Due to such properties, the dicyandiamide is sometimes referred to as a latent curing agent.

[0057] The present curable resin composition contains component (B) at 3.5 to 19.0 parts by mass, preferably 3.5 to 18.0 parts by mass, more preferably 4.0 to 16.0 parts by mass, more preferably 4.5 to 14.0 parts by mass, further 5.0 to 12.0 parts by mass, more further 5.5 to 10.0 parts by mass, particularly preferably 6.0 to 8.0 parts by mass, relative to 100 parts by mass of component (A). Regarding the content of component (B) in the present curable resin composition, in the case where it is (1) 3.5 parts by mass or more, there is an advantage that the cured product of the present curable resin composition cured at a low temperature has sufficient adhesive strength, and in the case where it is (b) 19.0 parts by mass or less, there is an advantage that the storage stability of the present curable resin composition is good, and the moisture resistance of the obtained cured product becomes good.

[0058] < Polymer particles having a core-shell structure (C) >

[0059] The present curable resin composition preferably contains polymer particles having a core-shell structure (C) (hereinafter, sometimes referred to as "component (C)") in addition to the above-mentioned component (A) and component (B). In the case where the present curable resin composition contains component (C), there is an advantage that it can provide a cured product (for example, an adhesive layer) that is excellent in impact peeling adhesion and adhesive strength.

[0060] In the present specification, the polymer particles having a core-shell structure refer to particles that form a layer structure of a core layer formed of a core polymer and a shell layer formed of a shell polymer.

[0061] As the component (C), there is no particular limitation to the structure as long as it has at least one core layer and at least one shell layer, and it can have a structure of three or more layers of an intermediate layer that coats the core layer and / or a shell layer that further coats the intermediate layer. In addition, in the component (C), the core layer and the shell layer can not form a complete layer structure. That is, the shell layer can coat at least a part of the core layer, and can not coat the entire core layer. In addition, a part of the shell polymer that constitutes the shell layer can enter the core layer.

[0062] In the component (C), it is preferable that the shell polymer be substantially chemically bonded (for example, graft-bonded) to the core polymer. The component (C) is more preferably a core-shell polymer particle formed by graft-polymerizing a monomer (shell monomer) that can be graft-copolymerized to the core layer (core polymer) to form a shell layer in the presence of the core layer. Such a polymerization operation can be performed, for example, by adding a shell monomer to a latex of the core polymer prepared in an aqueous polymer latex state and polymerizing it. The component (C) obtained by this operation can have a structure including the core layer present inside and at least one shell layer that is graft-polymerized to the surface of the core layer and covers the periphery or a part of the core layer.

[0063] Hereinafter, each layer that the component (C) can include will be described in detail.

[0064] <Core Layer>

[0065] In order to improve the toughness of the cured product of the composition, the core layer that the component (C) has is preferably an elastic core layer having the properties of a rubber.

[0066] From the viewpoints of good improvement effect on the toughness of the obtained cured product, good improvement effect on the impact peeling adhesion resistance of the obtained cured product, and poor affinity with the component (A) so that the viscosity increase over time due to swelling of the core layer is less likely to occur, the core layer preferably contains a diene-based rubber. By combining a plurality of monomers, a polymer of a wide composition can be designed, and thus the core layer preferably contains a (meth)acrylate-based rubber. In addition, in the case of improving the impact resistance at low temperatures without degrading the heat resistance of the cured product, the core layer preferably contains a silicone-based rubber. In other words, the core layer preferably contains one or more selected from the group consisting of a diene-based rubber, a (meth)acrylate-based rubber, and a silicone-based rubber.

[0067] (Diene-based Rubber)

[0068] The above diene-based rubber is preferably a polymer containing structural units derived from at least one monomer selected from among conjugated diene-based monomers (hereinafter, also referred to as conjugated diene units) 50 to 100% by mass, and structural units derived from a vinyl-based monomer other than the conjugated diene-based monomers, which can be copolymerized with the conjugated diene-based monomers 0 to 50% by mass.

[0069] As the above conjugated diene-based monomers, for example, 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2-chloro-1,3-butadiene, and the like can be given.

[0070] These conjugated diene-based monomers can be used alone or two or more can be used in combination.

[0071] In 100% by mass of the total structural units constituting the core layer, the content of the conjugated diene units in the core layer is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, further preferably 90 to 100% by mass. When the content of the conjugated diene units in the core layer is 50% by mass or more, the impact peeling adhesion of the obtained cured product can become better.

[0072] As the vinyl-based monomer other than the conjugated diene-based monomers, which can be copolymerized with the conjugated diene-based monomers, for example, styrene, a-methylstyrene, monochlorostyrene, dichlorostyrene, and the like vinyl aromatic hydrocarbons; acrylic acid, methacrylic acid, and the like acrylic acids; acrylonitrile, methacrylonitrile, and the like acrylonitriles; chloroethylene, bromoethylene, chlorobutadiene, and the like halogenated ethylenes; vinyl acetate; ethylene, propylene, butylene, isobutylene, and the like olefins; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene, and the like multifunctional monomers can be given.

[0073] These vinyl-based monomers can be used alone or two or more can be used in combination. Styrene is particularly preferable.

[0074] From the viewpoint of better toughness-improving effect of the obtained cured product, better impact peeling adhesion-improving effect of the obtained cured product, and less likely to cause viscosity increase over time due to swelling of the core layer because of poor affinity with Component (A), the core layer more preferably contains butadiene rubber as a homopolymer of 1,3-butadiene and / or butadiene-styrene rubber as a copolymer of 1,3-butadiene and styrene in the diene-based rubber, more preferably contains butadiene rubber and / or butadiene-styrene rubber (consists only of the same), further preferably contains butadiene rubber, and particularly preferably butadiene rubber (consists only of the same). From the viewpoint of improving the transparency of the cured product based on refractive index adjustment, butadiene-styrene rubber is preferable.

[0075] ((Meth)acrylate-based rubber)

[0076] The above (meth)acrylate-based rubber is preferably a polymer obtained by polymerizing a monomer mixture containing 50 mass% to 100 mass% of a structural unit derived from at least one monomer selected from (meth)acrylate-based monomers (hereinafter, sometimes referred to as (meth)acrylate-based unit) and 0 mass% to 50 mass% of a structural unit derived from a vinyl-based monomer other than the (meth)acrylate-based monomer, which is capable of copolymerizing with the (meth)acrylate-based monomer. Note that, in the present specification, "(meth)acrylate" means acrylate and / or methacrylate.

[0077] As the above (meth)acrylate-based monomer, for example, (i) (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid octyl ester, (meth)acrylic acid dodecyl ester, (meth)acrylic acid stearyl ester, (meth)acrylic acid behenyl ester, and the like (alkyl (meth)acrylate); (ii) (meth)acrylic acid phenoxyethyl ester, (meth)acrylic acid benzyl ester, and the like (aromatic ring-containing (meth)acrylate); (iii) (meth)acrylic acid hydroxyalkyl ester; (iv) (meth)acrylic acid glycidyl ester, (meth)acrylic acid glycidyl alkyl ester, and the like (glycidyl (meth)acrylate); (v) (meth)acrylic acid alkoxyalkyl ester; (vi) (meth)acrylic acid allyl ester, and (meth)acrylic acid allyl alkyl ester, and the like (allyl alkyl (meth)acrylate); (vii) polyfunctional (meth)acrylate such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and the like can be given.

[0078] As the (meth)acrylic acid hydroxyalkyl ester, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like (hydroxy straight chain alkyl (meth)acrylate, in particular, hydroxy straight chain C1-6 alkyl (meth)acrylate); caprolactone-modified hydroxy (meth)acrylate; a-(hydroxymethyl) methyl acrylate, a-(hydroxymethyl) ethyl acrylate, and the like (hydroxy branched chain alkyl (meth)acrylate); mono(meth)acrylate of a polyester diol (saturated polyester diol, in particular) obtained from a dibasic acid (phthalic acid, etc.) and a dihydric alcohol (propylene glycol, etc.), and the like (hydroxy-containing (meth)acrylate), and the like can be given.

[0079] These (meth)acrylate-based monomers can be used alone or in combination of two or more. As the (meth)acrylate-based monomers, ethyl (meth)acrylate, butyl (meth)acrylate, and 2- ethylhexyl (meth)acrylate are preferable.

[0080] As the vinyl-based monomers other than the (meth)acrylate-based monomers which can be copolymerized with the (meth)acrylate-based monomers, for example, (i) vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; (ii) acrylic acids such as acrylic acid and methacrylic acid; (iii) acrylonitriles such as acrylonitrile and methacrylonitrile; (iv) halogenated ethylenes such as chloroethylene, bromoethylene, and chlorobutadiene; (v) vinyl acetate; (vi) olefins such as ethylene, propylene, butylene, and isobutylene; and (vii) multi-functional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene can be given.

[0081] As the vinyl-based monomers other than the (meth)acrylate-based monomers which can be copolymerized with the (meth)acrylate-based monomers, one kind can be used alone or two or more kinds can be used in combination. From the viewpoint that the refractive index can be easily increased, styrene is particularly preferable.

[0082] (Silicone-based rubber)

[0083] As the silicone-based rubber, for example, (i) silicone-based polymers composed of alkyl or aryl 2-substituted siloxy units such as dimethylsiloxy, diethylsiloxy, methylphenylsiloxy, and diphenylsiloxy; (ii) silicone-based polymers composed of alkyl or aryl 1-substituted siloxy units such as organohydrogensiloxy in which a part of the alkyl group of the side chain is substituted with a hydrogen atom; and the like can be given.

[0084] These silicone-based polymers can be used alone or in combination of two or more. From the viewpoint that the heat resistance of the cured product can be imparted, among them, dimethylsiloxy, methylphenylsiloxy, and dimethylsiloxy-diphenylsiloxy are preferable, and from the viewpoint of easy availability, dimethylsiloxy is most preferable.

[0085] In order to improve the toughness of the obtained cured product, the glass transition temperature of the core layer is preferably 0°C or lower, more preferably -20°C or lower, further preferably -40°C or lower, and particularly preferably -60°C or lower.

[0086] In addition, the volume average particle diameter of the core layer is not particularly limited, and is preferably from 0.03 μm to 2 μm, more preferably from 0.05 μm to 1 μm, more preferably from 0.12 μm to 0.50 μm, more preferably from 0.12 μm to 0.28 μm, and further preferably from 0.14 μm to 0.25 μm. When the volume average particle diameter of the core layer is within this range, the core layer can be stably produced, and the heat resistance and impact resistance of the cured product can be made good. The method for measuring the volume average particle diameter of the core layer is described in detail in the Examples described later.

[0087] The core layer can be a single layer structure or a multilayer structure formed of layers having rubber elasticity. In addition, when the core layer is a multilayer structure, the polymer composition of each layer can differ from each other within the ranges disclosed above.

[0088] In one embodiment of the present application, an intermediate layer described in paragraphs

[0046] to

[0049] of WO2016-163491, for example, can be provided between the core layer and the shell layer.

[0089] <Shell Layer>

[0090] The shell layer is a polymer produced from a shell monomer (monomer for forming a shell layer). The polymer constituting the shell layer (shell polymer) serves to improve the compatibility of component (C) and component (A), and can allow component (C) to be dispersed in the cured product produced by curing the present curable resin composition and / or the present curable resin composition in the state of primary particles.

[0091] As the shell monomer, one kind of monomer (monomer) can be used alone, or two or more kinds of monomers can be used in combination. In the case where the shell monomer contains two or more kinds of monomers, the composition of the shell monomer, i.e., the kind and the content ratio of the monomers contained in the shell monomer, is not particularly limited. From the viewpoint of the compatibility and dispersibility of component (C) in the curable resin composition, the shell monomer is preferably an aromatic vinyl monomer, an acrylonitrile monomer, or a (meth)acrylate monomer, and more preferably a (meth)acrylate monomer. In particular, the shell monomer preferably contains methyl methacrylate.

[0092] In other words, the kind and the content ratio of the structural units contained in the shell layer are not particularly limited. From the viewpoint of the compatibility and dispersibility of the polymer component (C) in the present curable resin composition, the shell layer preferably contains a structural unit derived from one or more kinds of monomers selected from the group consisting of an aromatic vinyl monomer, an acrylonitrile monomer, and a (meth)acrylate monomer, and more preferably contains a structural unit derived from a (meth)acrylate monomer. In particular, the shell layer preferably contains a structural unit derived from methyl methacrylate.

[0093] For the shell layer, the structural units derived from one or more monomers selected from the group consisting of aromatic vinyl monomers, acrylonitrile monomers, and (meth)acrylate monomers are preferably contained in 10.0 to 99.5% by mass, more preferably 50.0 to 99.0% by mass, further preferably 65.0 to 98.0% by mass, particularly preferably 67.0 to 80.0% by mass, and most preferably 67.0 to 85.0% by mass, of the shell layer (shell polymer) 100% by mass.

[0094] As specific examples of the aromatic vinyl monomers, mention can be made of styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, and the like.

[0095] As specific examples of the acrylonitrile monomers, mention can be made of acrylonitrile or methacrylonitrile, and the like.

[0096] As specific examples of the (meth)acrylate monomers, the same content as that described in the item of "Core layer" above applies, and thus the description is omitted here.

[0097] In the present curable resin composition and the cured product obtained by curing the present curable resin composition, in order to maintain a good dispersion state of component (C) without aggregation, from the viewpoint of chemically bonding component (C) to component (A), the shell layer preferably has a structural unit derived from a monomer containing a reactive group. In other words, the shell layer of component (C) preferably contains a reactive group.

[0098] As the reactive group possessed by the shell layer of component (C), one or more selected from the group consisting of, for example, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an imide group, a carboxylic acid group, a carboxylic anhydride group, a cyclic ester group, a cyclic amide group, a benzoxazine group, and a cyanate ester group is preferable. As the reactive group possessed by the shell layer of component (C), one or more selected from the group consisting of, for example, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an imide group, a carboxylic acid group, a carboxylic anhydride group, a cyclic ester group, a cyclic amide group, a benzoxazine group, and a cyanate ester group is preferable.

[0099] Since the obtained cured product has excellent adhesive strength and impact peeling adhesion, the reactive group possessed by the shell layer of component (C) is preferably an epoxy group. In other words, the shell layer of component (C) preferably has a structural unit derived from a monomer having an epoxy group, i.e., preferably has an epoxy group.

[0100] As specific examples of the monomers having the above-described epoxy group, mention can be made of glycidyl (meth)acrylate, 4-hydroxybutyl glycidyl (meth)acrylate, allyl glycidyl ether, and the like, which are glycidyl group-containing vinyl monomers.

[0101] In the case where the shell layer of component (C) has an epoxy group, from the viewpoint of the adhesion strength and impact peeling resistance of the obtained cured product, and the storage stability of the composition, the content of the epoxy group in the shell layer of component (C) is preferably more than 0 mmol / g and 2.0 mmol / g or less, more preferably 0.1 mmol / g to 2.0 mmol / g, further preferably 0.3 mmol / g to 1.5 mmol / g, relative to the total mass of the shell layer of component (C). According to this configuration, the aggregation of component (C) can be inhibited, and component (C) can be dispersed in the cured product in the state of primary particles, as a result of which the adhesion strength and impact peeling resistance of the cured product can be improved.

[0102] The monomer having an epoxy group is preferably used for the formation of the shell layer, more preferably used only for the formation of the shell layer. In other words, the core layer and the intermediate layer preferably do not have an epoxy group.

[0103] In one embodiment of the present application, the shell layer of component (C) preferably does not have an epoxy group from the viewpoint of the storage stability of the present curable resin composition.

[0104] As a specific example of the monomer having a hydroxyl group, which is a source of a reactive group, included in the shell layer of component (C), the aforementioned hydroxyalkyl (meth)acrylate can be given.

[0105] In the case where the shell layer includes a structural unit derived from a multifunctional monomer having 2 or more radical-polymerizable double bonds, swelling of component (C) in the curable resin composition can be prevented, and the viscosity of the curable resin composition decreases, and the handleability improves, and thus is preferred. On the other hand, from the viewpoint of the toughness-improving effect and the impact peeling resistance-improving effect of the obtained cured product, the shell layer preferably does not include a structural unit derived from a multifunctional monomer having 2 or more radical-polymerizable double bonds.

[0106] As a specific example of the aforementioned multifunctional monomer, a conjugated diene monomer such as butadiene is not included, and the following can be given: allyl (meth)acrylate, allylalkyl (meth)acrylate (s) such as allyl (meth)acrylate; allyloxyalkyl (meth)acrylate (s); (poly)ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and the like, which are multifunctional (meth)acrylates having 2 or more (meth)acryloyl groups; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and the like.

[0107] Among these multifunctional monomers, allyl methacrylate and triallyl isocyanurate are preferred.

[0108] In one embodiment of the present application, the shell layer of component (C) is preferably a polymer containing only, for example, the following structural units: (a) structural units derived from an aromatic vinyl monomer (particularly preferably styrene) at 0 to 50 mass% (preferably 1 to 50 mass%, more preferably 2 to 48 mass%); (b) structural units derived from an acrylonitrile monomer (particularly preferably acrylonitrile) at 0 to 50 mass% (preferably 0 to 30 mass%, more preferably 10 to 25 mass%); (c) structural units derived from a (meth)acrylate monomer ((i) preferably one or more selected from the group consisting of methyl acrylate, butyl acrylate, and methyl methacrylate; (ii) particularly preferably methyl methacrylate) at 0 to 100 mass% (preferably 5 to 100 mass%, more preferably 70 to 95 mass%); and (d) structural units derived from a monomer having an epoxy group (particularly glycidyl methacrylate) at 1 to 50 mass% (preferably 2 to 35 mass%, more preferably 3 to 20 mass%). Herein, in the shell layer of component (C), the total of (i) structural units derived from an aromatic vinyl monomer, structural units derived from an acrylonitrile monomer, structural units derived from a (meth)acrylate monomer, and structural units derived from a monomer having an epoxy group is 100 mass%, and (ii) 0 mass% of a certain structural unit means that the shell layer of component (C) can not contain the structural unit.

[0109] The above monomer components can be used alone or in combination of two or more. The shell layer of component (C) can contain structural units derived from monomers other than the above monomers.

[0110] The shell layer of component (C) can be a single layer structure or a multilayer structure. In the case of a multilayer structure, the polymer composition of each layer can be different from one another within the above range.

[0111] "Volume average particle diameter (Mv) of component (C)"

[0112] The volume average particle diameter (Mv) of component (C) is not particularly limited, and is preferably from 0.01 μm to 2.00 μm, more preferably from 0.03 μm to 0.60 μm, more preferably from 0.05 μm to 0.40 μm, more preferably from 0.10 μm to 0.30 μm, more preferably from 0.15 μm to 0.30 μm, more preferably from 0.16 μm to 0.28 μm, more preferably from 0.17 μm to 0.27 μm, further preferably from 0.18 μm to 0.25 μm, from the viewpoint of industrial productivity and the processability of the curable resin composition. When the volume average particle diameter (Mv) of component (C) is (a) 0.01 μm or more, the viscosity of the curable resin composition is low, and thus the processability is good; and (b) 2.00 μm or less, the polymerization time of component (C) is short, and thus the industrial productivity is high. The method for measuring the volume average particle diameter (Mv) of component (C) is described in detail in the Examples described later.

[0113] Component (C) is preferably dispersed in the form of primary particles in the present curable resin composition. "Component (C) is dispersed in the form of primary particles" (hereinafter, also referred to as primary dispersion) in the present specification means that a plurality of particles of component (C) are dispersed independently of each other (without contact) in reality, and the dispersion state can be confirmed by, for example, dissolving a part of the curable resin composition in a solvent such as methyl ethyl ketone, and supplying it to a particle diameter measuring device based on laser scattering or the like, and measuring the particle diameter of component (C) in the curable resin composition.

[0114] In addition, "stable dispersion" of component (C) means that component (C) is not aggregated, separated, or precipitated in the continuous layer, but is dispersed for a long time under constant ordinary conditions. In addition, it is preferable that the distribution of component (C) in the continuous layer does not substantially change, and "stable dispersion" can be maintained even if the viscosity is reduced by heating these compositions within a range that is not dangerous and stirring.

[0115] Note that, as component (C), one kind of core-shell polymer particle can be used alone, or two or more kinds of core-shell polymer particles can be used in combination.

[0116] <Method for producing component (C)>

[0117] (Method for producing core layer)

[0118] The formation of the core layer of component (C) can be made by polymerizing the core monomer by a known polymerization method such as emulsion polymerization, suspension polymerization, micro-suspension polymerization, or the like. As the specific emulsion polymerization, suspension polymerization, and micro-suspension polymerization, the methods described in International Publication No. 2005 / 028546, International Publication No. 2006 / 070664, or the like can be appropriately used.

[0119] (Method for forming the shell layer and the intermediate layer)

[0120] The intermediate layer of component (C) can be formed by polymerizing the intermediate layer-forming monomer by a known radical polymerization. In the case where the rubbery elastomer constituting the core layer is obtained in the form of an emulsion, the polymerization of the intermediate layer-forming monomer is preferably performed by emulsion polymerization.

[0121] The shell layer of component (C) can be formed by polymerizing the shell monomer by a known radical polymerization. In the case where the polymer particle precursor constituted by the core layer or the core layer coated with the intermediate layer is obtained in the form of an emulsion, the polymerization of the shell monomer is preferably performed by emulsion polymerization. As the emulsion polymerization, the method described in International Publication No. 2005 / 028546, or the like can be appropriately used.

[0122] An emulsifier (dispersant) is used in the emulsion polymerization. As the emulsifier, the following can be given: (i) (i-1) alkyl or aryl sulfonic acid such as dioctyl sulfosuccinic acid and dodecylbenzenesulfonic acid; alkyl or aryl ether sulfonic acid; alkyl or aryl sulfuric acid such as dodecylsulfuric acid; alkyl or aryl ether sulfuric acid; alkyl or aryl-substituted phosphoric acid; alkyl or aryl ether-substituted phosphoric acid; N-alkyl or aryl sarcosinic acid such as dodecylsarcosinic acid; oleic acid and alkyl or aryl carboxylic acid such as stearic acid; alkyl or aryl ether carboxylic acid; various acids; and (i-2) anionic emulsifiers (dispersants) such as alkali metal salts or ammonium salts of these acids; (ii) nonionic emulsifiers (dispersants) such as alkyl or aryl-substituted polyethylene glycol; and (iii) dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives.

[0123] These emulsifiers (dispersants) can be used alone or in combination of two or more.

[0124] It is preferable to reduce the amount of the emulsifier (dispersant) used within a range that does not affect the dispersion stability of the aqueous latex of the polymer particles. Further, the higher the water solubility of the emulsifier (dispersant) is, the more preferable it is. When the water solubility is high, the water washing removal of the emulsifier (dispersant) becomes easy, and the adverse effects on the finally obtained cured product can be easily prevented.

[0125] In the case of using the emulsion polymerization method, a peroxide (for example, an organic peroxide), a chain transfer agent, a surfactant, and the like can be used as needed.

[0126] The polymerization temperature, pressure, deoxidation, and the like at the time of polymerization can be applied within a known range.

[0127] From the viewpoint of the balance between the storage stability of the curable resin composition and the toughness improvement effect of the obtained cured product, the content of the component (C) in the present curable resin composition is preferably 1 part by mass to 100 parts by mass of the component (A), more preferably 5 parts by mass to 90 parts by mass, further preferably 10 parts by mass to 80 parts by mass, more further preferably 20 parts by mass to 70 parts by mass, particularly preferably 30 parts by mass to 60 parts by mass.

[0128] <Curability improver (D)>

[0129] The present curable resin composition preferably contains a curability improver (D). In the present specification, the "curability improver (D)" is sometimes referred to as "component (D)". The component (D) is a compound that functions as a catalyst for promoting the reaction of the epoxy group possessed by the component (A) with the epoxide-reactive group possessed by the component (B) and the component other than the component (A) contained in the curable resin composition (i.e., the curing reaction).

[0130] As the component (D), as long as it has the above-described catalyst action, there is no particular limitation, and examples that can be given are: ureas such as (a) 3-(3,4-dichlorophenyl)-1,1-dimethylurea, p-chlorophenyl-N,N-dimethylurea (trade name: Monuron), 3-phenyl-1,1-dimethylurea (trade name: Fenuron), 3,4-dichlorophenyl-N,N-dimethylurea (trade name: Diuron), N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea (trade name: Chlortoluron), 1,1-dimethylphenylurea (trade name: Dyhard), and the like; tertiary amines such as (b) benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol introduced into a poly(p-vinylphenol) matrix, triethylenediamine, N,N-dimethylpiperidine, and the like; (c) C1-C12 alkylene imidazole, N-aryl imidazole, 2-methylimidazole, 2-ethyl-2-methylimidazole, N-butylimidazole, 1-cyanoethyl-2-undecylimidazole • an addition product of trimellitic acid, epoxy resin and imidazole, etc. imidazoles; (d) 6-hexanolactam, etc. Component (D) can be enclosed in a microcapsule, etc. or a latent catalyst which becomes active only at an elevated temperature can also be used. As component (D), one of these can be used alone or two or more of them can be used in combination.

[0131] The curable resin composition preferably contains 0.1 to 10.0 parts by mass, more preferably 0.2 to 5.0 parts by mass, further preferably 0.5 to 3.0 parts by mass, and particularly preferably 0.8 to 2.0 parts by mass of component (D) per 100 parts by mass of component (A). When the content (a) of component (D) is 0.1 parts by mass or more, the curability of the curable resin composition becomes good; and when (b) is 10.0 parts by mass or less, the storage stability of the curable resin composition becomes good, having the advantage of easy handling.

[0132] <Inorganic Filler>

[0133] The curable resin composition preferably contains an inorganic filler. By containing an inorganic filler, the curable resin composition has the effect that the rigidity of the obtained cured product at a high temperature is more excellent.

[0134] As the inorganic filler, dry silica, wet silica, aluminum silicate, magnesium silicate, calcium silicate and / or silicate; reinforcing fillers such as wollastonite, talc, dolomite and carbon black; or calcium oxide, heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, titanium oxide, iron oxide, aluminum micropowder, zinc oxide, active zinc oxide, etc. can be given. These inorganic fillers can be used alone or two or more of them can be used in combination.

[0135] The above-mentioned dry silica is also called fumed silica. As the fumed silica, hydrophilic fumed silica whose surface is not treated and hydrophobic fumed silica which is manufactured by chemically treating the silanol group portion of the hydrophilic fumed silica with silane or siloxane can be given, and from the viewpoint of dispersibility in component (A), the hydrophobic fumed silica is preferred.

[0136] The content of the inorganic filler in the curable resin composition is preferably 1 to 300 parts by mass, more preferably 5 to 200 parts by mass, and further preferably 10 to 150 parts by mass per 100 parts by mass of component (A). When the content of the inorganic filler is within the above-mentioned range, the obtained cured product has the advantage that the rigidity and the adhesive strength at a high temperature are further excellent.

[0137] <Other Components>

[0138] According to necessity, the present curable resin composition can contain components other than the above-mentioned components (other components). As the other components, there can be mentioned: curing agents other than dicyandiamide, phenol compounds, blocked carbamates

[0139] <Method for producing curable resin composition>

[0140] The production method of the present curable resin composition is not particularly limited, and various methods can be used, and there can be mentioned: for example, a method in which the component (C) obtained in an aqueous latex state is brought into contact with the component (A) after removing unnecessary components such as water; a method in which the component (C) is temporarily extracted from an organic solvent, mixed with the component (A), and then the organic solvent is removed; and the like. As such a production method, specifically, the method described in International Publication No. 2005 / 028546 is preferably used. More specifically, the present curable resin composition is preferably produced by a production method comprising the following 1st process to 3rd process in this order.

[0141] • 1st process: after mixing an aqueous latex containing the component (C) (in detail, a reaction mixture after producing the component (C) by emulsion polymerization) with an organic solvent having a solubility of 5 mass% to 40 mass% in water at 20°C, further mixing with excess water, and coagulating the component (C);

[0142] • 2nd process: after separating / recovering the coagulated component (C) from the liquid phase, mixing again with an organic solvent, and obtaining an organic solvent solution of the polymer particles (B);

[0143] • 3rd process: after further mixing the above-mentioned organic solvent solution of the component (C) with the component (A), distilling off the above-mentioned organic solvent.

[0144] ​To the dispersion in which component (C) is dispersed in component (A) in the form of primary particles obtained by the above-mentioned first to third processes, an additional component (A), component (B), an additional component (D) as necessary, and an inorganic filler, and other components are added, and they are mixed, whereby the present curable resin composition can be obtained. In addition, according to this production method, the present curable resin composition in a state in which component (C) is dispersed in the form of primary particles can be obtained. When the present curable resin composition is a composition in which component (C) is dispersed in component (A) in the form of primary particles, the obtained cured product has the advantage that the impact peeling adhesive strength is excellent.

[0145] In addition, the present curable resin composition can be produced by using a disperser such as a three-roll machine, a roll mill, a kneader, and the like having a high mechanical shearing force to re-disperse component (C) in the form of a powder obtained by drying after coagulation by a method such as salting-out in component (A). At this time, component (C) can be efficiently dispersed in component (A) by applying a mechanical shearing force to component (A) and component (C) at a high temperature. In the case where the present curable resin composition is produced by applying a mechanical shearing force using a disperser, the temperature at the time of dispersing component (C) in component (A) (the temperature at the time of applying a mechanical shearing force) is preferably from 50°C to 200°C, more preferably from 70°C to 170°C, further preferably from 80°C to 150°C, and particularly preferably from 90°C to 120°C.

[0146] The present curable resin composition can be stored in a sealed state after all the components to be blended are blended in advance, and used as a single-dose curable resin composition which is cured by heating or light irradiation after coating. In addition, a two-dose or a multiple-dose curable resin composition which contains an A liquid containing component (A) as a main component and component (C), and a C liquid containing component (B) and, as necessary, component (D), and, further as necessary, component (C), which are prepared separately from the A liquid, and which are mixed before use, can be prepared in advance. Note that the present curable resin composition is particularly advantageous when used as a single-dose curable resin composition.

[0147] In the case where the present curable resin composition is a two-dose or a multiple-dose curable resin composition, component (C) can be contained in at least one of the A liquid and the C liquid. That is, component (C) can be contained only in the A liquid, can be contained only in the C liquid, or can be contained in both the A liquid and the C liquid.

[0148] (2-2. Adherend)

[0149] Hereinafter, a bonded body (hereinafter, sometimes referred to as "the present bonded body") of one embodiment of the present application will be described in detail. The "bonded body" is sometimes referred to as a "substrate" or an "adhesion substrate".

[0150] As the material of the present bonded body, for example, wood, metal, plastic, glass, and the like can be given. More specifically, for example, (i) steel materials such as cold-rolled steel and hot-dipped galvanized steel, (ii) aluminum materials such as aluminum and clad aluminum, and (iii) various plastic substrates such as general-purpose plastics, engineering plastics, CFRP, GFRP, and the like can be given.

[0151] In the present production method, at least two bonded bodies, i.e., a first bonded body and a second bonded body, are used as the bonded bodies. The first bonded body and the second bonded body in the present production method can be bonded bodies formed of the same kind of material or bonded bodies formed of different kinds of material. As the first bonded body and the second bonded body, at least one of which is preferably a steel material, and more preferably both of which are steel materials, from the advantages of being inexpensive and high in strength, and excellent in weldability and formability. That is, in one embodiment of the present application, the first bonded body and / or the second bonded body is preferably a steel material, and more preferably both of the first bonded body and the second bonded body are steel materials.

[0152] The thickness of the first bonded body and the second bonded body in the present production method is not particularly limited, and is preferably 0.4 mm to 3.2 mm, more preferably 0.8 mm to 2.4 mm, and further preferably 1.2 mm to 1.6 mm. The first bonded body and the second bonded body in the present production method can have the same thickness or different thicknesses.

[0153] The average thickness (X) (hereinafter, sometimes simply referred to as "(X)") of the first bonded body and the second bonded body is not particularly limited, and is preferably 0.4 mm to 3.2 mm, more preferably 0.8 mm to 2.4 mm, and further preferably 1.2 mm to 1.6 mm. Note that the average thickness (X) of the first bonded body and the second bonded body can be calculated on the basis of the following formula: Average thickness (X) of the first bonded body and the second bonded body = (thickness of the first bonded body + thickness of the second bonded body) / 2.

[0154] (2-3. Step (i) (bonding step))

[0155] The process (i) in the present production method is a process of joining the second adherend to the first adherend after the present curable resin composition is applied to the first adherend. At this time, the present curable resin composition applied to the first adherend is joined to the first adherend and the second adherend in a manner of being interposed between the first adherend and the second adherend. In addition, at this time, the curable resin composition interposed between the first adherend and the second adherend can protrude from the first adherend and / or the second adherend by a portion. In addition, the present curable resin composition can be applied to the second adherend as needed in addition to the first adherend. The process (i) of one embodiment of the present application (hereinafter, sometimes referred to as "the present process (i)") can be considered as a process of obtaining a structure in which the first adherend, the present curable resin composition, and the second adherend are sequentially layered (hereinafter, sometimes referred to as "structure (i)").

[0156] In the present process (i), the method of applying the present curable resin composition to the first adherend (and the second adherend as needed) is not particularly limited, and the application can be performed by any method. For example, a method of extruding the present curable resin composition to the first adherend in a bead shape, a monofilament shape, or a swirl shape and applying the same using an application robot; a mechanical application method such as a caulking gun; a spray method or a flow coating method; and the present curable resin composition can be applied to the first adherend using other manual application means.

[0157] In the present process (i), it is preferable to adjust the thickness of the present curable resin composition in the obtained structure (i) so that the ratio (Y / X) of the thickness (Y) of the cured product obtained by curing the curable resin composition to the average thickness (X) of the first adherend and the second adherend is 0.5 to 10.0. The thickness of the curable resin composition in the obtained cured product in which the value of (Y / X) is 0.5 to 10.0 varies depending on the average thickness of the first adherend and the second adherend used, and thus cannot be uniformly specified, and for example, it is preferable to be 0.2 mm to 4 mm, more preferable to be 0.3 mm to 3 mm, and further preferable to be 0.4 mm to 2 mm. In other words, in the present process (i), it is preferable to adjust the thickness of the applied curable resin composition to be within the above range.

[0158] The method of adjusting the thickness of the present curable resin composition in the obtained structure (i) is not particularly limited, and for example, (1) a method of extending the curable resin composition applied to the first adherend using a doctor blade or the like; or (2) a method of extending the present curable resin composition by pressing the same through the two adherends in a state of being interposed between the two adherends when joining the second adherend to the first adherend, and the like can be given.

[0159] The present process (i) preferably has a process (thickness adjustment process) of adjusting the thickness of the present curable resin composition in the obtained structure (i) as described above, so that the thickness of a cured product of the present curable resin composition is a desired thickness.

[0160] (2-4. Process (ii) (curing process))

[0161] The process (ii) in the present production method is a process of curing the present curable resin composition present between the first adherend and the second adherend in the structure (i) obtained in the process (i). By the process (ii), a laminate (hereinafter, sometimes referred to as "laminate") in which the two adherends (the first adherend and the second adherend) are adhered by a cured product of the present curable resin composition obtained by curing the present curable resin composition can be obtained.

[0162] In the process (ii) (hereinafter, sometimes referred to as "the present process (ii)") of one embodiment of the present application, the present curable resin composition in the structure (i) is cured by heating. Therefore, the present process (ii) can also be considered as a "heating process" or a "heating and curing process".

[0163] The curing temperature (temperature at which the present curable resin composition is heated) in the present process (ii) is 105°C to 145°C, preferably 115°C to 140°C, and more preferably 125°C to 135°C. Note that the "curing temperature" refers to the temperature of the atmosphere of the space in which the present curable resin composition is heated, and in the case where a baking furnace is used for the process (ii), the setting temperature of the baking furnace. By setting the curing temperature in the process (ii) to 145°C or lower, the fuel or the like required for heating can be reduced, and contribution to the realization of carbon neutrality can be made.

[0164] The curing time (time for which the present curable resin composition is heated) in the present process (ii) is 10 minutes to 60 minutes, preferably 15 minutes to 40 minutes, and more preferably 15 minutes to 30 minutes. Note that the "curing time" refers to the time for which the space in which the present curable resin composition is heated is maintained, and in the case where a baking furnace is used for the present process (ii), the time from when the structure (i) is put into the baking furnace until it is taken out. By setting the curing time in the present process (ii) to 60 minutes or lower, the fuel or the like required for heating can be reduced, and contribution to the realization of carbon neutrality can be made.

[0165] In the present specification, as described above, the curing temperature is 145°C or lower (105°C to 145°C), and the heat curing of the curable resin composition containing the epoxy resin under the condition that the curing temperature is 60 minutes or lower is referred to as "low-temperature curing". The present step (ii) can also be considered as a low-temperature curing step.

[0166] In the case where the present curable resin composition is used as an adhesive for an automobile, in other words, in the case where the present production method is used in the production of a vehicle body structure, it is preferable to coat the present curable resin composition to an automobile member as an adherend, further coat a coating layer such as an electrodeposition coating, and cure the present curable resin composition while baking / curing the coating layer from the viewpoint of shortening the steps / simplifying the process.

[0167] (2-5. Laminates and Cured Products)

[0168] Hereinafter, the laminate of one embodiment of the present application and the cured product in the laminate (cured product of the present curable resin composition) will be described in detail. In the present specification, the "laminate of one embodiment of the present application" is sometimes referred to as "the present laminate", and the "cured product of one embodiment of the present application" is sometimes referred to as "the present cured product".

[0169] <Ratio of thickness of cured product to thickness of adherend>

[0170] The ratio (Y / X) of the thickness (Y) of the present cured product in the present laminate to the average thickness (X) of the first adherend and the second adherend is 0.5 to 10.0. By controlling the ratio (Y / X) to be 0.5 to 10.0, in other words, by making the ratio (Y / X) 0.5 to 10.0, by performing the above-described steps (i) and (ii), even in the case of low-temperature curing, a laminate in which the adherends are bonded by a cured product having a high elastic modulus in a high-temperature environment can be provided. The ratio (Y / X) in the present laminate is more preferably more than 0.5 and 5.0 or lower, and further preferably 0.7 to 3.0.

[0171] <Glass transition temperature of cured product>

[0172] The glass transition temperature (Tgl) of the present cured product on a Celsius scale is not particularly limited, and is preferably 120°C or higher, more preferably 122°C or higher, and further preferably 125°C or higher from the viewpoint of being able to reduce the elastic modulus of the cured product in a high-temperature environment. Note that the measurement method of the glass transition temperature (Tgl) of the cured product is described in the description of the examples. Note that Tgl can be considered as the glass transition temperature on a Celsius scale of the cured product of the present curable resin composition cured at a low temperature, or the glass transition temperature on a Celsius scale of the cured product in the laminate immediately after step (ii) (immediately after the laminate is produced).

[0173] The glass transition temperature (Tg2) of the cured product obtained by heating and curing the present curable resin composition under sufficient heating conditions (in the present specification, conditions of a curing temperature of 130°C and a curing time of 2 hours) is not particularly limited, and is preferably 20°C or higher, more preferably 50°C or higher, further preferably 80°C or higher, further preferably 100°C or higher, more further preferably 120°C or higher, and particularly preferably 130°C or higher. Note that the glass transition temperature (Tg2) of the cured product is measured as described in the description of the Examples. Note that Tg2 can be considered as the glass transition temperature on a Celsius scale of the cured product obtained by heating and curing the present curable resin composition under sufficient heating conditions (in the present specification, conditions of a curing temperature of 130°C and a curing time of 2 hours).

[0174] <Migration rate of glass transition temperature>

[0175] The migration rate of the glass transition temperature of the cured product refers to the ratio (Tg1 / Tg2) of the glass transition temperature on a Celsius scale (Tg1) of the cured product obtained by low-temperature curing the curable resin composition (1) containing an epoxy resin and the glass transition temperature on a Celsius scale (Tg2) of the cured product obtained by heating and curing under sufficient heating conditions (in the present specification, conditions of a curing temperature of 130°C and a curing time of 2 hours). Note that the migration rate of the glass transition temperature of the cured product can be calculated by the following formula:

[0176] Migration rate of the glass transition temperature of the cured product = (glass transition temperature on a Celsius scale (Tg1) (°C) of the cured product obtained by curing the curable resin composition at a curing temperature of 130°C for a curing time of 20 minutes / glass transition temperature on a Celsius scale (Tg2) (°C) of the cured product obtained by curing the curable resin composition at a curing temperature of 130°C for a curing time of 120 minutes) x 100.

[0177] The crosslinking density (conversion rate of curing) of the cured product obtained by curing the curable resin composition containing the epoxy resin varies depending on the curing temperature and the curing time. As a result, the glass transition temperature of the cured product obtained by curing the curable resin composition containing the epoxy resin also varies depending on the curing temperature and the curing time. In particular, the present inventors have found that the glass transition temperature of the cured product obtained when the curable resin composition is cured at a low temperature has a tendency to greatly decrease compared to the case where the heat curing is performed under sufficient heating conditions (for example, conditions where the curing temperature is 130°C and the curing time is 2 hours). Note that if the curable resin composition is cured for a sufficiently long time, the curing reaction ends (the conversion rate of curing reaches 100% or substantially 100%) and each cured product formed from each composition reaches the inherent glass transition temperature. In the present specification, the sufficient heating conditions refer to the heating conditions where the curing reaction ends. In addition, the glass transition temperature (Tg2) of the cured product obtained by heat curing under the sufficient heating conditions can also be considered as the glass transition temperature of the cured product at the point in time where the curing reaction ends.

[0178] The present inventors have considered that in the case where the curable resin composition is cured at a low temperature, the decrease in the glass transition temperature at the time of low-temperature curing is one of the reasons for the great decrease in the elastic modulus of the obtained cured product under a high-temperature environment. In contrast, the present inventors have considered that if the decrease in the glass transition temperature at the time of low-temperature curing can be suppressed, a cured product having a high elastic modulus under a high-temperature environment can be provided.

[0179] The migration rate of the glass transition temperature (Tg1 / Tg2) is an index showing the degree of suppression of the decrease in the glass transition temperature at the time of low-temperature curing. The higher Tg1 / Tg2, the more the decrease in the glass transition temperature at the time of low-temperature curing can be suppressed, in other words, it means that the decrease in the elastic modulus of the cured product under a high-temperature environment is suppressed. Therefore, from the viewpoint of providing a cured product having a high elastic modulus even under a high-temperature environment, the migration rate of the glass transition temperature (Tg1 / Tg2) of the cured product in the laminate obtained by the present production method is preferably 80% or more, more preferably 81% or more, and further preferably 83% or more. The migration rate of the glass transition temperature (Tg1 / Tg2) of the cured product in the laminate can be measured by the method described in the examples.

[0180] Note that the migration rate of the glass transition temperature can be controlled by adjusting the composition of the curable resin composition (in particular, the composition of the epoxy resin), the ratio of the thickness of the cured product to the thickness of the adherend, and the like.

[0181] <Storage modulus (E') at 120°C>

[0182] The present cured product is a cured product having a high elastic modulus under a high temperature environment. In the present specification, the "elastic modulus under a high temperature" of the cured product can be evaluated from the storage modulus E' at 120°C of the cured product. The storage modulus at 120°C of the cured product can be measured by a tensile mode of dynamic viscoelasticity measurement, and the frequency can be measured at, for example, 1 Hz.

[0183] The storage modulus at 120°C of the present cured product is preferably 0.07 GPa or higher, more preferably 0.08 GPa or higher, further preferably 0.09 GPa or higher, and particularly preferably 0.10 GPa or higher. The higher the storage modulus at 120°C of the cured product, the more excellent the elastic modulus under a high temperature environment of the cured product. The upper limit of the storage modulus at 120°C of the present cured product is not particularly limited, and can be, for example, 5.0 GPa or lower.

[0184] <100°C storage modulus (E')

[0185] In the present specification, the "elastic modulus under a high temperature" of the cured product can be evaluated from the storage modulus E' at 100°C of the cured product. The storage modulus at 100°C of the cured product can be measured by a tensile mode of dynamic viscoelasticity measurement, and the frequency can be measured at, for example, 1 Hz.

[0186] The storage modulus at 100°C of the present cured product is preferably 1.05 GPa or higher, more preferably 1.1 GPa or higher, further preferably 1.2 GPa or higher, and particularly preferably 1.3 GPa or higher. The higher the storage modulus at 100°C of the cured product, the more excellent the elastic modulus under a high temperature environment of the cured product. The upper limit of the storage modulus at 100°C of the present cured product is not particularly limited, and can be, for example, 5.0 GPa or lower.

[0187] <23°C storage modulus (E')

[0188] The present cured product is also excellent in the elastic modulus at room temperature. In the present specification, the "elastic modulus at room temperature" of the cured product can be evaluated from the storage modulus E' at 23°C of the cured product. The storage modulus at 23°C of the cured product can be measured by a tensile mode of dynamic viscoelasticity measurement, and the frequency can be measured at, for example, 1 Hz.

[0189] The storage modulus at 23°C of the present cured product is preferably 1.0 GPa or higher, more preferably 1.5 GPa or higher, and further preferably 2.0 GPa or higher. The higher the storage modulus at 23°C of the cured product, the more excellent the elastic modulus at room temperature of the cured product. The upper limit of the storage modulus at 23°C is not particularly limited, and can be, for example, 5.0 GPa or lower.

[0190] The storage modulus at 23°C of the cured product of the curable resin composition cured at low temperature is 1.0 GPa or greater, and the glass transition temperature (Tg1) of the cured product on a Celsius scale is 120°C or greater, which means that even if the cured product is cured at low temperature and for a short time, the cured product is a laminate in which the cured product having a high elastic modulus at high temperature environment bonds the adherends. Therefore, the storage modulus at 23°C of the cured product in the laminate obtained by the production method is 1.0 GPa or greater, and the glass transition temperature (Tg1) of the cured product on a Celsius scale is preferably 120°C or greater.

[0191] <Use of the laminate>

[0192] The laminate of the present application is suitably used in the bonding of parts in the production of, for example, a vehicle body of an automobile and a vehicle (Shinkansen, electric train, etc.), an aircraft, a spacecraft, a space station, a structure, a building, a wind power plant, etc. That is, in one embodiment of the present application, the production method of the present application is included as one step, and a production method of a vehicle body structure is provided.

[0193] 〔3. Other〕

[0194] One embodiment of the present application can include the following configuration.

[0195] 〔1〕 A production method of a laminate which is produced by sequentially laminating a first adherend, a cured product of a curable resin composition, and a second adherend,

[0196] The production method of the laminate includes:

[0197] (i) applying the curable resin composition to the first adherend and bonding the second adherend to the first adherend (bonding step); and

[0198] (ii) curing the curable resin composition (curing step),

[0199] wherein the curable resin composition contains: an epoxy resin (A), and 3.5 parts by mass to 19.0 parts by mass of dicyandiamide (B) per 100 parts by mass of the epoxy resin (A),

[0200] of the total amount of the epoxy resin (A) being 51% by mass to 100% by mass of unmodified bisphenol A type epoxy resin (A-1),

[0201] the curing temperature of the curable resin composition in the step (ii) is 105°C to 145°C,

[0202] The curing time of the curable resin composition in the process (ii) is 10 minutes to 60 minutes,

[0203] The ratio (Y / X) of the thickness (Y) of the cured product to the average thickness (X) of the first adherend and the second adherend is 0.5 to 10.0.

[0204] 〔2〕 The method for producing a laminate according to 〔1〕, wherein

[0205] The migration rate of the glass transition temperature of the cured product is 80% or more;

[0206] Here, the migration rate of the glass transition temperature of the cured product is a value calculated by the following formula:

[0207] The migration rate of the glass transition temperature of the cured product = (glass transition temperature on a Celsius basis (Tg1) (°C) of a cured product obtained by curing the curable resin composition at a curing temperature of 130°C for a curing time of 20 minutes / glass transition temperature on a Celsius basis (Tg2) (°C) of a cured product obtained by curing the curable resin composition at a curing temperature of 130°C for a curing time of 120 minutes) x 100.

[0208] 〔3〕 The method for producing a laminate according to 〔1〕 or 〔2〕, wherein

[0209] The storage modulus of the cured product at 23°C is 1 GPa or more, the storage modulus being a value determined by dynamic viscoelasticity measurement in a tensile mode under a condition of a frequency of 1 Hz.

[0210] 〔4〕 The method for producing a laminate according to any one of 〔1〕 to 〔3〕, wherein

[0211] The storage modulus of the cured product at 120°C is 0.07 GPa or more, the storage modulus being a value determined by dynamic viscoelasticity measurement in a tensile mode under a condition of a frequency of 1 Hz.

[0212] 〔5〕 The method for producing a laminate according to any one of 〔2〕 to 〔4〕, wherein

[0213] The glass transition temperature (Tg1) of the cured product is 120°C or more.

[0214] 〔6〕 The method for producing a laminate according to any one of 〔1〕 to 〔5〕, wherein

[0215] The epoxy resin (A) does not include an aliphatic polybasic acid-modified epoxy resin (A-3).

[0216] 〔7〕 The method for manufacturing a laminate according to any one of <1> to <5>, wherein

[0217] The epoxy resin (A) contains an aliphatic polyacid-modified epoxy resin (A-3), and the content of the aliphatic polyacid-modified epoxy resin (A-3) in the epoxy resin is more than 0 mass% and less than 3 mass%.

[0218] 〔8〕 The method for manufacturing a laminate according to any one of <1> to <7>, wherein

[0219] The first adherend and / or the second adherend is a steel sheet.

[0220] 〔9〕 The method for manufacturing a laminate according to any one of <1> to <8>, wherein

[0221] The curable resin composition further contains polymer particles (C) 1 mass part to 100 mass part having a core-shell structure including a core layer and a shell layer, with respect to 100 mass parts of the epoxy resin (A).

[0222] 〔10〕 The method for manufacturing a laminate according to any one of <1> to <9>, wherein

[0223] The curable resin composition further contains a curing accelerator (D) 0.1 mass part to 15 mass parts, with respect to 100 mass parts of the epoxy resin (A).

[0224] 〔11〕 The method for manufacturing a laminate according to <9>, wherein

[0225] The core layer contains one or more selected from the group consisting of diene-based rubber, (meth)acrylate-based rubber, and organosiloxane-based rubber.

[0226] 〔12〕 The method for manufacturing a laminate according to <9> or <11>, wherein

[0227] The core layer is butadiene rubber and / or butadiene / styrene rubber.

[0228] 〔13〕 The method for manufacturing a laminate according to any one of <10> to <12>, wherein

[0229] The shell layer contains a structural unit derived from one or more monomers selected from the group consisting of aromatic vinyl-based monomers, acrylonitrile-based monomers, and (meth)acrylate-based monomers.

[0230] 〔14〕 A method for manufacturing a vehicle body structure, the method comprising the method for manufacturing a laminate according to any one of <1> to <13>.

[0231] Examples

[0232] The following Examples show one embodiment of the present application in more detail, but the present application is not limited to these Examples.

[0233] 〔Materials〕

[0234] The following shows the substances used in the Examples and Comparative Examples.

[0235] (Ingredient (A))

[0236] Ingredient (A-1): JER828 (manufactured by Mitsubishi Chemical, liquid bisphenol A type epoxy resin at normal temperature, epoxy equivalent: 184-194)

[0237] Ingredient (A-2): JER807 (manufactured by Mitsubishi Chemical, liquid bisphenol F type epoxy resin at normal temperature, epoxy equivalent: 160-175)

[0238] Ingredient (A-3): JER871 (manufactured by Mitsubishi Chemical, dimer acid-modified epoxy resin, epoxy equivalent: 410 g / eq)

[0239] (Other epoxy resins)

[0240] HyPox RA840 (manufactured by CVC, rubber-modified epoxy resin, epoxy equivalent: 350)

[0241] (Ingredient (B))

[0242] Dyhard 100S (manufactured by AlzChem, dicyandiamide)

[0243] (Ingredient (C))

[0244] As the ingredient (C), a polymer particle prepared by the following method was used. Note that, as described later, the ingredient (C) was used in the form of a dispersion (M-1) in which the prepared polymer particle was dispersed in the ingredient (A) (ingredient (A-1)).

[0245] 1. Formation of core layer

[0246] Production Example 1-1; Preparation of polybutadiene rubber latex (R-1)

[0247] Into a pressure-resistant polymerizer of 100 L in volume, deionized water 200 parts by mass, tripotassium phosphate 0.03 parts by mass, potassium dihydrogen phosphate 0.25 parts by mass, ethylenediaminetetraacetic acid disodium salt (EDTA) 0.002 parts by mass, ferrous sulfate 7 hydrate (FE) 0.001 parts by mass, and sodium dodecylbenzenesulfonate (SDS) 1.5 parts by mass as an emulsifier were put. Subsequently, while the raw materials put in were stirred, the gas inside the pressure-resistant polymerizer was replaced with nitrogen, whereby oxygen was sufficiently removed from the inside of the pressure-resistant polymerizer. Subsequently, butadiene (BD) 100 parts by mass was put into the pressure-resistant polymerizer, and the temperature inside the pressure-resistant polymerizer was raised to 45°C. Thereafter, p-menthane hydroperoxide (PHP) 0.015 parts by mass was put into the pressure-resistant polymerizer, and then sodium formaldehyde sulfoxylate (SFS) 0.04 parts by mass was put into the pressure-resistant polymerizer, and polymerization was started. At the 10th hour after the start of polymerization, devolatilization was performed under reduced pressure, and the monomers unused in the polymerization and remaining were removed by devolatilization, whereby the polymerization was ended. In the polymerization, PHP, EDTA, and FE were added to the pressure-resistant polymerizer in arbitrary amounts and at any timing, respectively. By such a polymerization operation, a latex (R-1) containing a core layer (polybutadiene rubber particles) with polybutadiene rubber as a main component was obtained. The volume average particle diameter of the polybutadiene rubber particles contained in the obtained latex was 0.10 μm.

[0248] Preparation of polybutadiene rubber latex (R-2)

[0249] Into a pressure-resistant polymerizer of 100 L in volume, the polybutadiene rubber latex (R-1) obtained in Production Example 1-1 was put in 7 parts by mass as a solid component, deionized water 200 parts by mass, tripotassium phosphate 0.03 parts by mass, EDTA 0.002 parts by mass, and FE 0.001 parts by mass. Subsequently, while the raw materials put in were stirred, the gas inside the pressure-resistant polymerizer was replaced with nitrogen, whereby oxygen was sufficiently removed from the inside of the pressure-resistant polymerizer. Thereafter, BD 93 parts by mass was put into the pressure-resistant polymerizer, and the temperature inside the pressure-resistant polymerizer was raised to 45°C. Subsequently, PHP 0.02 parts by mass was put into the pressure-resistant polymerizer, and then SFS 0.10 parts by mass was put into the pressure-resistant polymerizer, and polymerization was started. At the 30th hour after the start of polymerization, devolatilization was performed under reduced pressure, and the monomers unused in the polymerization and remaining were removed by devolatilization, whereby the polymerization was ended. In the polymerization, PHP, EDTA, and FE were added to the pressure-resistant polymerizer in arbitrary amounts and at any timing, respectively. By such a polymerization operation, a latex (R-2) containing a core layer (polybutadiene rubber particles) with polybutadiene rubber as a main component was obtained. The volume average particle diameter of the polybutadiene rubber particles contained in the obtained latex was 0.20 μm.

[0250] 2. Preparation of polymer particles having a core-shell structure (formation of a shell layer)

[0251] Preparation of core-shell polymer latex (L-1)

[0252] Into a glass reactor, 262 parts by mass of the polybutadiene rubber latex (R-2) prepared in Production Example 1-2 (containing 87 parts by mass of polybutadiene rubber particles) and 57 parts by mass of deionized water were charged. Here, the above glass reactor had a thermometer, a stirrer, a reflux condenser, a nitrogen gas inlet, and a monomer addition device. The gas in the glass reactor was replaced with nitrogen, and the charged raw materials were stirred at 60°C while the nitrogen replacement was performed. Subsequently, 0.004 parts by mass of EDTA, 0.001 parts by mass of FE, and 0.2 parts by mass of SFS were continuously added to the glass reactor over 120 minutes. Thereafter, a mixture of a shell-forming monomer (1 part by mass of methyl methacrylate (MMA), 6 parts by mass of styrene (ST), 2 parts by mass of acrylonitrile (AN), and 4 parts by mass of glycidyl methacrylate (GMA)) and 0.04 parts by mass of cumene hydroperoxide (CHP) was continuously added to the glass reactor over 120 minutes. After the addition was completed, 0.04 parts by mass of CHP was added to the glass reactor, and the stirring of the mixture in the glass reactor was further continued for 2 hours to terminate the polymerization. By the above operation, an aqueous latex (L-1) containing polymer particles having a core-shell structure (component (C)) was obtained. The polymerization conversion rate of the monomer component was 99% or more. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex (L-1) was 0.21 μm. The content of the epoxy group was 2.2 mmol / g with respect to the total amount of the shell layer.

[0253] 3. Preparation of a dispersion (M) in which component (C) is dispersed in component (A)

[0254] Production Example 3-1; Preparation of a dispersion (M-1)

[0255] To a 1 L mixing tank at 25°C was introduced methyl ethyl ketone (MEK) 132 g. Next, while stirring the MEK, the aqueous latex (L-1) 132 g (containing component (C) 40 g) containing the polymer particles obtained in Production Example 2-1 was introduced into the mixing tank. After the raw materials in the mixing tank were uniformly mixed, while stirring the raw materials in the mixing tank, water 200 g was introduced into the mixing tank at a supply rate of 80 g / min. After the supply of water was completed, the above stirring was promptly stopped, and a slurry formed of the coagulum containing component (C) and the aqueous phase containing a small amount of organic solvent was obtained. The above coagulum was floatable. Next, the aqueous phase 360 g was discharged through the discharge port at the lower portion of the mixing tank, so that the coagulum containing a portion of the aqueous phase remained in the mixing tank. To the obtained coagulum was added MEK 90 g, and they were uniformly mixed, and a dispersion in which the core-shell polymer was uniformly dispersed in MEK was obtained. To the obtained dispersion was added 60 g of component (A-1), and they were uniformly mixed. The MEK was removed from the obtained mixture using a rotary evaporator. By this operation, a dispersion (M-1) in which component (C) was dispersed in component (A-1) was obtained.

[0256] (Curing accelerator (D))

[0257] Dyhard UR200 (manufactured by AlzChem, 3-(3,4-dichlorophenyl)

[0258] (Inorganic filler)

[0259] Fumed silica: CAB-O-SIL TS-720 (manufactured by CABOT, fumed silica surface-treated with polydimethylsiloxane)

[0260] Calcium carbonate: WHITON SB (manufactured by Shiraishi Calcium, untreated heavy calcium carbonate)

[0261] Calcium oxide: CML #31 (manufactured by Oji Calcium, calcium oxide surface-treated with fatty acid).

[0262] [Measurement method]

[0263] The measurement methods of each property measured in the examples are shown below.

[0264] (Volume average particle diameter of polymer particles)

[0265] The volume average particle diameter (Mv) of the polymer particles dispersed in the core-shell polymer latex described in the production examples was measured using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.). In the measurement, the core-shell polymer latex diluted with deionized water was used as the measurement sample. Note that the measurement was performed under the following conditions: the refractive index of water and the refractive index of each polymer particle were input, the measurement time was 600 seconds, and the sample concentration was adjusted so that the Signal Level was within the range of 0.6 to 0.8.

[0266] (Measurement of glass transition temperature and storage modulus)

[0267] The measurement method of the glass transition temperature and the storage modulus of the cured product obtained by curing the curable resin composition was as follows: the curable resin composition was coated between two pieces of fluorine-coated steel sheets having a width of 25 mm and a length of 100 mm, the two pieces of steel sheets were overlapped in a manner that the thickness of the curable resin composition was 0.2 to 1.3 mm, and then the cured product was obtained by curing (low-temperature curing) under conditions of a curing temperature of 130°C and a curing time of 20 minutes, whereby a laminate in which the two pieces of steel sheets were bonded by the cured product was obtained. The plate-shaped cured product was peeled off from the obtained laminate and removed, and the thickness thereof was measured with a vernier caliper. Here, as the thickness of the steel sheets, the same thickness as that used in the corresponding example or comparative example was used (i.e., a steel sheet having a thickness of 1.6 mm, 0.8 mm, or 0.5 mm). The cured product was cut into a long strip shape having a length of 30 mm and a width of 5 mm, and using a dynamic viscoelasticity measuring device (DMA), the storage modulus E' at 23°C, the storage modulus E' at 100°C, and the storage modulus E' at 120°C, and the glass transition temperature (Tg1) as the temperature in degrees Celsius at which the tangent (tan δ) became the maximum were measured under a tensile mode at a frequency of 1 Hz.

[0268] (Mobility of glass transition temperature)

[0269] The curing conditions of the curable resin composition were changed to a curing temperature of 130°C and a curing time of 2 hours, and otherwise, the same operation as described above was performed to measure the glass transition temperature (Tg2) in degrees Celsius of the cured product at the time point at which the curing reaction ended for each curable resin composition. The mobility of the glass transition temperature was calculated based on the following formula:

[0270] Mobility of glass transition temperature = (Tg1 (°C) / Tg2 (°C)) x 100.

[0271] (Examples 1 to 7 and Comparative Examples 1 to 4)

[0272] The components were measured out and mixed thoroughly in the proportions shown in Table 1, whereby a curable resin composition was obtained. The curable resin composition was applied to a fluorine-coated steel sheet (first adherend) having a thickness as described in Table 1, and another fluorine-coated steel sheet (second adherend) having a thickness as described in Table 1 was laminated to the first adherend (laminating step). The resulting structure was heated and cured (low-temperature curing) at a curing temperature of 130°C and a curing time of 20 minutes (curing step), whereby a laminate was obtained. The physical properties of the resulting laminate (cured product in the laminate) were measured and evaluated. The results are shown in Table 1.

[0273]

[0274] Industrial applicability

[0275] According to one embodiment of the present application, it is possible to provide a method for manufacturing a laminate, which can manufacture a laminate in which adherends are bonded by a cured product having a high elastic modulus in a high-temperature environment, even if curing is performed under conditions of low temperature and short time. Such a manufacturing method can be suitably used for the bonding of iron sheets, CFRP, aluminum sheets, and concrete. Therefore, one embodiment of the present application can be suitably used in the fields of vehicles, aircraft, space, machinery, electricity, construction, and civil engineering.

Claims

1. A method for manufacturing a laminate, wherein the laminate is formed by sequentially layering a first substrate, a cured product obtained by curing a curable resin composition, and a second substrate. The method for manufacturing this laminate includes: Step (i) involves applying the curable resin composition to the first substrate, thereby bonding the second substrate to the first substrate; and Step (ii) involves curing the curable resin composition. in, The curable resin composition comprises: an epoxy resin (A), and dicyandiamide (B) in an amount of 3.5 to 19.0 parts by weight relative to 100 parts by weight of the epoxy resin (A). Of the total 100% by mass of the epoxy resin (A), the epoxy resin (A) comprises 51% to 100% by mass of unmodified bisphenol A type epoxy resin (A-1). The curing temperature of the curable resin composition in step (ii) is 105°C to 145°C. The curing time of the curable resin composition in step (ii) is 10 minutes to 60 minutes. The ratio (Y / X) of the thickness (Y) of the cured material to the average thickness (X) of the first and second adherends is 0.5 to 10.

0.

2. The method for manufacturing a laminate according to claim 1, wherein, The glass transition temperature mobility of the cured product is above 80%; Here, the glass transition temperature mobility of the cured product is calculated using the following formula: The glass transition temperature migration rate of the cured product = (glass transition temperature (Tg1) (°C) of the cured product obtained by curing the curable resin composition at a curing temperature of 130°C and a curing time of 20 minutes / glass transition temperature (Tg2) (°C) of the cured product obtained by curing the curable resin composition at a curing temperature of 130°C and a curing time of 120 minutes) × 100.

3. The method for manufacturing a laminate according to claim 1, wherein, The solidified material has a storage modulus of 1 GPa or more at 23°C. The storage modulus is a value obtained by measuring the tensile mode of dynamic viscoelasticity at a frequency of 1 Hz.

4. The method for manufacturing a laminate according to claim 1, wherein, The solidified material has a storage modulus of 0.07 GPa or higher at 120°C. The storage modulus is a value obtained by measuring the tensile mode of dynamic viscoelasticity at a frequency of 1 Hz.

5. The method for manufacturing a laminate according to claim 2, wherein, The glass transition temperature (Tg1) of the cured product is above 120°C.

6. The method for manufacturing a laminate according to claim 1, wherein, The epoxy resin (A) does not contain aliphatic polyacid modified epoxy resin (A-3).

7. The method for manufacturing a laminate according to claim 1, wherein, The epoxy resin (A) comprises an aliphatic polyacid modified epoxy resin (A-3), wherein the content of the aliphatic polyacid modified epoxy resin (A-3) in the epoxy resin is greater than 0% by mass and less than 3% by mass.

8. The method for manufacturing a laminate according to claim 1, wherein, The first and / or second bonded body is a steel plate.

9. The method for manufacturing a laminate according to claim 1, wherein, Relative to 100 parts by weight of the epoxy resin (A), the curable resin composition further contains 1 to 100 parts by weight of polymer particles (C) having a core-shell structure comprising a core layer and a shell layer.

10. The method for manufacturing a laminate according to claim 1, wherein, Relative to 100 parts by weight of the epoxy resin (A), the curable resin composition further comprises 0.1 to 15 parts by weight of a curing accelerator (D).

11. The method for manufacturing a laminate according to claim 9, wherein, The core layer comprises one or more selected from diene rubber, (meth)acrylate rubber, and organosiloxane rubber.

12. The method for manufacturing a laminate according to claim 9, wherein, The core layer is butadiene rubber and / or butadiene / styrene rubber.

13. The method for manufacturing a laminate according to claim 9, wherein, The shell comprises structural units derived from one or more monomers selected from aromatic vinyl monomers, acrylonitrile monomers, and (meth)acrylate monomers.

14. A method for manufacturing a vehicle body structure, the method comprising the method for manufacturing a laminated body according to any one of claims 1 to 13.

Images