Epoxy resin composition

Abstract

To provide an epoxy resin composition having excellent thermal cycles and adhesiveness.SOLUTION: An epoxy resin composition contains (A) a liquid epoxy resin, (B) a thiol compound, and (C) an amine latent curing agent. The epoxy resin composition is liquid at 25°C. The epoxy resin composition satisfies the following conditions: (1) a product that was cured at 80°C for 30 minutes shows a flexural modulus of 0.1 GPa-8.0 GPa at -25°C; (2) a product that was cured at 80°C for 30 minutes shows a flexural modulus of 0.05 GPa-4.0 GPa at 25°C; (3) a product that was cured at 80°C for 30 minutes shows, when measured with a differential scanning calorimeter (DSC), a residual calorific value of 15% or less; (4) a viscosity ratio (n2 / n1) is 0.9 or more to 1.5 or less where n1 means a viscosity immediately after its compounding and n2 means a viscosity after its storage for 48 hours at 30°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an epoxy resin composition.

Background Art

[0002] Epoxy resins and epoxy resin compositions are used in a wide range of applications such as insulating materials, encapsulating materials, adhesives, and conductive materials for electronic devices and electrical and electronic components.

[0003] In particular, epoxy resins and epoxy resin compositions used in electronic devices are required to have a significant improvement in productivity, portability in mobile applications of electronic devices, and improvement in reliability, along with the high functionality, miniaturization, and thinning of electronic devices, for example, the miniaturized integration of semiconductor chips and the high density of circuits.

[0004] Epoxy resins and epoxy resin compositions are cured with a curing agent and used in the above various applications.

[0005] As a method for curing an epoxy resin composition, there is a method using a so-called two-component epoxy resin composition in which an epoxy resin and a curing agent are mixed and cured at the time of use. In the two-component epoxy resin composition, a method of using a thiol-based curing agent and an amine-based curing agent in combination as the curing agent is known.

[0006] The two-component epoxy resin composition can be cured well at low temperatures, but it is necessary to store the epoxy resin and the curing agent separately, and at the time of use, it is necessary to measure both and mix them quickly and uniformly, and the handling tends to be complicated. Furthermore, once the epoxy resin and the curing agent are mixed, the pot life thereafter is limited, so they cannot be mixed in large quantities in advance.

[0007] In order to solve these problems, an epoxy resin composition containing an amine-based latent curing agent having potential in an amine-based curing agent has been proposed. However, such an epoxy resin composition tends to have difficulty in achieving both storage stability and curability (especially curability at low temperatures).

[0008] For example, Patent Documents 1 and 2 both propose epoxy resin compositions with improved low-temperature curability. [Prior Art Documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-143134 [Patent Document 2] International Publication No. 2017 / 057019 [Summary of the Invention] [Problems to be Solved by the Invention]

[0010] However, in the epoxy resin compositions disclosed in Patent Documents 1 and 2, although attempts have been made to improve low-temperature curability, there is still room for improvement in thermal cycling and adhesiveness, and they are not suitable for application to electronic components such as adhesion to organic substrates and silicon.

[0011] Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide an epoxy resin composition excellent in thermal cycling and adhesiveness. [Means for Solving the Problems]

[0012] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by an epoxy resin composition having specific physical property values, and have completed the present invention.

[0013] That is, the present invention relates to the following. [1] An epoxy resin composition comprising (A) a liquid epoxy resin, (B) a thiol compound, and (C) an amine-based latent curing agent, which is liquid at 25°C and satisfies the following conditions (1) to (4); (1) The cured product cured at 80°C for 30 minutes has a flexural modulus at -25°C of 0.1 GPa to 8.0 GPa; (2) The cured product cured at 80°C for 30 minutes has a flexural modulus at 25°C of 0.05 GPa to 4.0 GPa; (3) The cured product cured at 80°C for 30 minutes has a residual heat generation amount of 15% or less when measured by a differential scanning calorimeter (DSC); (4) The viscosity ratio (n2 / n1) of the viscosity (n2) after storing at 30°C for 48 hours with respect to the viscosity (n1) immediately after blending is 0.9 times or more and 1.5 times or less. [2] The epoxy resin composition according to [1], further satisfying the following condition (5); (5) When analyzing the epoxy resin composition in a nitrogen atmosphere by a differential scanning calorimeter (DSC) at an isothermal temperature of 80°C, the time from reaching 80°C to reaching the peak top of the heat flow rate is 20 minutes or less. [3] (A) The liquid epoxy resin contains (A1) a flexible epoxy resin, and the epoxy resin composition according to [1] or [2]. [4] (C) The particle size of the amine-based latent curing agent is 0.9 or more, and the epoxy resin composition according to any one of [1] to [3]. [5] (C) The amine-based latent curing agent is of the microcapsule type, and the epoxy resin composition according to any one of [1] to [4]. [6] The epoxy resin composition according to any one of [1] to [5], further containing (D) a filler. [7] (B) The thiol compound contains an ester-free thiol compound, and the epoxy resin composition according to any one of [1] to [6]. [8] (B) The epoxy resin composition according to [7], wherein the thiol compound contains a compound represented by the following formula (1) and / or (2).

Chemical formula

Chemical formula

Advantages of the Invention

[0014] According to the present invention, an epoxy resin composition excellent in thermal cycle and adhesiveness can be provided.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiments") will be described in detail. However, the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0016] The epoxy resin composition of the present embodiment contains (A) a liquid epoxy resin, (B) a thiol compound, and (C) an amine-based latent curing agent, is liquid at 25°C, and satisfies the following conditions (1) to (4): (1) The cured product cured at 80°C for 30 minutes has a flexural modulus of 0.1 GPa to 8.0 GPa at -25°C; (2) The cured product cured at 80°C for 30 minutes has a flexural modulus of 0.05 GPa to 4.0 GPa at 25°C; (3) The cured product cured at 80°C for 30 minutes has a residual heat generation amount of 15% or less when measured by a differential scanning calorimeter (DSC); (4) The viscosity magnification (n2 / n1) of the viscosity (n2) after storing at 30°C for 48 hours with respect to the viscosity (n1) immediately after blending is 0.9 times or more and 1.5 times or less.

[0017] By satisfying the above conditions, the epoxy resin composition of the present embodiment has good thermal cycle properties and excellent adhesiveness. Therefore, the epoxy resin composition of the present embodiment is not particularly limited, but for example, it can be suitably used as an electronic material adhesive such as a package substrate.

[0018] In the present embodiment, the term "liquid state" refers to a state in which fluidity is exhibited at 25°C, specifically, a state in which the viscosity at 25°C is 500 Pa·s or less.

[0019] In the epoxy resin composition, the ability to cure at a low temperature of 80°C as opposed to a general curing temperature of 100°C or higher means that it has low-temperature curability.

[0020] The epoxy resin composition of the present embodiment satisfies the following condition (1). (1) The cured product cured at 80°C for 30 minutes has a flexural modulus of 0.1 GPa to 8.0 GPa at -25°C.

[0021] In the epoxy resin composition of the present embodiment, the flexural modulus at -25°C of the cured product cured at 80°C for 30 minutes is preferably 0.2 GPa to 7.0 GPa, and more preferably 0.3 GPa to 6.0 GPa. In the epoxy resin composition of the present embodiment, as a method for making the flexural modulus at -25°C of the cured product cured at 80°C for 30 minutes within the above range, it is not particularly limited, but for example, a method of adjusting the content of the preferred components described later, or a method of applying heat uniformly to the entire epoxy resin composition rather than locally when curing the epoxy resin composition in which each component is blended can be mentioned.

[0022] In the epoxy resin composition of the present embodiment, when the flexural modulus at -25°C of the cured product cured at 80°C for 30 minutes is equal to or higher than the lower limit value, it can withstand the strain with the adherend during thermal cycling and peeling is less likely to occur. Also, when it is equal to or lower than the upper limit value, the stress during thermal cycling can be relaxed and cracking is less likely to occur.

[0023] The epoxy resin composition of this embodiment satisfies the following condition (2). (2) The cured product cured at 80°C for 30 minutes has a flexural modulus at 25°C of 0.05 GPa to 4.0 GPa.

[0024] In the epoxy resin composition of this embodiment, the flexural modulus at 25°C of the cured product cured at 80°C for 30 minutes is preferably 0.1 GPa to 3.0 GPa, and more preferably 0.2 GPa to 2.0 GPa. In the epoxy resin composition of this embodiment, the method for making the flexural modulus at 25°C of the cured product cured at 80°C for 30 minutes fall within the above range is not particularly limited. For example, a method of adjusting the content of the preferred components described later, or a method of selecting curing conditions such that the entire (B) thiol compound contributes as a curing agent before the (C) amine-based latent curing agent reacts with the (A) liquid epoxy resin can be mentioned.

[0025] In the epoxy resin composition of this embodiment, when the flexural modulus at 25°C of the cured product cured at 80°C for 30 minutes is equal to or higher than the lower limit value, the strength and toughness are sufficiently high, so the crack resistance is excellent. On the other hand, when it is equal to or lower than the upper limit value, the elastic modulus is sufficiently low, and external stresses such as impact, thermal expansion, and contraction can be alleviated, and the adhesive layer is less likely to be broken due to impact, thermal expansion, and contraction.

[0026] The epoxy resin composition of this embodiment satisfies the following condition (3). (3) The cured product cured at 80°C for 30 minutes has a residual heat generation amount of 15% or less when measured with a differential scanning calorimeter (DSC).

[0027] In the epoxy resin composition of this embodiment, the residual heat generation amount of the cured product cured at 80°C for 30 minutes when measured with a DSC is preferably 12.5% or less, more preferably 10% or less. Even more preferably, there is no such residual heat generation amount, that is, it is 0%.

[0028] In the epoxy resin composition of the present embodiment, the fact that the residual heat generation amount is low means that curing has progressed, indicating excellent physical properties of the cured product.

[0029] In the epoxy resin composition of the present embodiment, the method for making the residual heat generation amount within the above range is not particularly limited. For example, a method of uniformly blending as an epoxy resin composition at the time of blending, or a method of blending such that the content of the (B) thiol compound is in the range of 0.5 to 2.0 equivalents as the thiol group equivalent with respect to 1 equivalent of the epoxy group can be mentioned.

[0030] The epoxy resin composition of the present embodiment satisfies the following condition (4). (4) The viscosity ratio (n2 / n1) of the viscosity (n2) after storage at 30°C for 48 hours to the viscosity (n1) immediately after blending is 0.9 times or more and 1.5 times or less.

[0031] In the epoxy resin composition of the present embodiment, the upper limit of the viscosity ratio (n2 / n1) is preferably 1.4 times or less, more preferably 1.3 times or less, and the lower limit of the viscosity ratio (n2 / n1) is preferably 0.93 times or more, 0.95 times or more.

[0032] In the epoxy resin composition of the present embodiment, when the (B) thiol compound is used as the curing agent, satisfying this condition (4) means ensuring the stability such as the reaction and sedimentation state of the resin of the epoxy resin composition, and the physical properties of the obtained cured product, particularly the moisture resistance. In the epoxy resin composition of the present embodiment, the method for making the viscosity ratio (n2 / n1) within the above range is not particularly limited. For example, a method of blending the (C) amine-based latent curing agent after blending the (A) liquid epoxy resin and the (B) thiol compound, or a method of not applying excessive heat during blending can be mentioned.

[0033] The epoxy resin composition of the present embodiment preferably satisfies the following condition (5). When the epoxy resin composition is analyzed by a differential scanning calorimeter (DSC) under a nitrogen atmosphere at an isothermal temperature of 80°C, the time from reaching 80°C to the peak top of the heat flow rate is 20 minutes or less.

[0034] In the epoxy resin composition of this embodiment, the upper limit of the time until reaching the peak top is preferably 17.5 minutes or less, more preferably 15 minutes or less. Also, in the epoxy resin composition of this embodiment, the lower limit of the time until reaching the peak top is preferably more than 1 minute, more preferably more than 3 minutes.

[0035] In the epoxy resin composition of this embodiment, when the time until the peak top is 20 minutes or less, it indicates that the reaction proceeds uniformly and there is little curing unevenness, meaning that there are few parts where strain is applied when a cycle test is performed. In the epoxy resin composition of this embodiment, when the time until the peak top is greater than the lower limit value, the heat generation amount of curing per unit time until curing decreases, so the temperature rise becomes lower and the residual stress after curing decreases. Therefore, it tends to have good cured product physical properties.

[0036] In the epoxy resin composition of this embodiment, the method of setting the time until the peak top within the above range is not particularly limited. For example, a method of appropriately selecting (C) the type and amount of the amine-based latent curing agent, the combination of (C) the amine-based latent curing agent with (A) the liquid epoxy resin and (B) the thiol compound, etc. can be mentioned.

[0037] In this embodiment, each of the above conditions can be specifically measured by the method described in the examples below.

[0038] [(A) Liquid epoxy resin] The epoxy resin composition of this embodiment contains (A) a liquid epoxy resin.

[0039] The liquid epoxy resin (A) used in this embodiment preferably has a viscosity of 100 Pa·s or less at 25°C and preferably contains two or more epoxy groups in one molecule. The liquid epoxy resin (A) is not limited to the following as long as it can achieve the effects of the present invention. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, tetrabromobisphenol A type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, tetrabromobiphenyl type epoxy resin, diphenyl ether type epoxy resin, benzophenone type epoxy resin, phenyl benzoate type epoxy resin, diphenyl sulfide type epoxy resin, diphenyl sulfoxide type epoxy resin, diphenyl sulfone type epoxy resin, diphenyl disulfide type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, hydroquinone type epoxy resin, methylhydroquinone type epoxy resin, dibutylhydroquinone type epoxy resin, resorcin type epoxy resin, methylresorcin type epoxy resin, catechol type epoxy resin, N,N-diglycidylaniline type epoxy resin and other bifunctional epoxy resins; N,N-diglycidylaminobenzene type epoxy resin, o-(N,N-diglycidylamino)toluene type epoxy resin, triazine type epoxy resin and other trifunctional epoxy resins; tetraglycidyldiaminodiphenylmethane type epoxy resin, diaminobenzene type epoxy resin and other tetrafunctional epoxy resins; phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene type epoxy resin, naphthol aralkyl type epoxy resin, brominated phenol novolac type epoxy resin and other polyfunctional epoxy resins.

[0040] Furthermore, it is preferable that the liquid epoxy resin (A) contains a flexible epoxy resin (A1). The flexible epoxy resin (A1) preferably contains two or more epoxy groups in one molecule and exhibits flexibility. Specifically, although not particularly limited, for example, polyalkylene glycol type epoxy resins, rubber-modified epoxy resins, urethane-modified epoxy resins, dimer acid-modified epoxy resins, polysulfide-modified epoxy resins and other flexible component-modified epoxy resins, or elastomer-added type epoxy resins, urethane resin-added type epoxy resins and other toughness component-added type epoxy resins can be mentioned. In addition, 2-ethylhexyl glycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, hydrogenated bisphenol A type epoxy resin, silicone-modified epoxy resin, (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, butanediol diglycidyl ether, trimethylolpropane diglycidyl ether, polytetramethylene ether glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexane type diglycidyl ether, dicyclopentadiene type diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane type epoxy resin, cresyl glycidyl ether, p-s-butylphenyl glycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 1,2-epoxy-4-(2-methyloxiranyl)-1-methylcyclohexane, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, aliphatic epoxy resins such as glycidyl neodecanoate can also be used as reactive diluents. These may be used alone or in combination of two or more.

[0041] (A) As the liquid epoxy resin, from the viewpoints of low elasticity and plane strain fracture toughness, polyalkylene glycol type epoxy resin, rubber-modified epoxy resin, urethane-modified epoxy resin, and dimer acid-modified epoxy resin are preferred, and from the viewpoint of adhesiveness to the liquid crystal polymer, polyalkylene glycol type epoxy resin is more preferred. Specifically, alkylene oxide-modified bisphenol A type epoxy resin and 1,6-hexanediol diglycidyl ether are preferably used.

[0042] In the epoxy resin composition of the present embodiment, in the (A) liquid epoxy resin, the content of the (A1) flexible epoxy resin is preferably in the range of 15 parts by mass to 85 parts by mass with respect to 100 parts by mass in total of the (A) liquid epoxy resin. In the epoxy resin composition of the present embodiment, when the content of the (A1) flexible epoxy resin is 15 parts by mass or more with respect to 100 parts by mass in total of the (A) liquid epoxy resin, the effect of the flexible epoxy resin tends to be sufficiently exhibited, and a sufficiently low elastic modulus and sufficient toughness tend to be obtained. Therefore, the crack resistance determined from the plane strain fracture toughness value also tends to be excellent. On the other hand, in the epoxy resin composition of the present embodiment, when the content of the (A1) flexible epoxy resin is 85 parts by mass or less with respect to 100 parts by mass in total of the (A) liquid epoxy resin, an excessive increase in the flexible part can be suppressed, so that sufficient strength can be ensured and sufficient adhesive strength tends to be obtained.

[0043] [(B) Thiol compound] The epoxy resin composition of this embodiment contains a (B) thiol compound. The (B) thiol compound is not limited to the following as long as it can achieve the effects of the present invention, but from the perspective of the physical properties of the obtained cured product, it preferably contains two or more thiol groups in one molecule. Specifically, although not particularly limited, for example, 3,3'-dithiobipropionic acid, trimethylolpropane tris(thioglycolate), pentaerythritol tetrakis(thioglycolate), ethylene glycol dithioglycolate, 1,4-bis(3-mercaptobutyryloxy)butane, tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptopropionate), 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluril, 4-butanedithiol, 1,6-hexanedithiol, 1,10-decanedithiol, etc. can be mentioned. These may be used alone or in combination of two or more.

[0044] (B) From the viewpoints of low elasticity and plane strain fracture toughness, the thiol compound is preferably 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and from the viewpoint of low-temperature curability, pentaerythritol tetrakis(3-mercaptopropionate) and pentaerythritol tetrakis(3-mercaptobutyrate) are more preferable.

[0045] Furthermore, as the (B) thiol compound, it is preferable to contain an ester-free (having no ester bond) thiol compound. In the epoxy resin composition of the present embodiment, by using an ester-free thiol compound having no ester bond as the (B) thiol compound, hydrolysis hardly occurs even under high-temperature and high-humidity conditions, and the retention rate of the adhesive strength is increased.

[0046] More preferably, as the (B) thiol compound, the compound represented by the following formula (1) and / or (2) is included. [Chemical formula] [Chemical formula] (In formulas (1) and (2), R1 to R5 each independently represent a linear or branched divalent hydrocarbon group or hetero group having 1 to 6 carbon atoms)

[0047] In the epoxy resin composition of the present embodiment, when the compound represented by the above formula (1) and / or (2) is included as the (B) thiol compound, the reactivity is high and the adhesive strength tends to be high.

[0048] [(C) Amine-based latent curing agent] The epoxy resin composition of the present embodiment contains a (C) amine-based latent curing agent. The (C) amine-based latent curing agent is not limited to the following as long as the effects of the present invention can be achieved. For example, imidazole compounds, dicyandiamide and its derivatives, amine-epoxy adducts, amine-urea adducts, or curing agents obtained by coating these, curing agents formed by complex formation with inclusion compounds, curing agents adsorbed on porous bodies, and the like can be mentioned. Specific examples thereof include, but are not limited to, Novacure HX-3721, HX-3722, HX-3613, HX-3921HP, HXA4922HP, Fujicure FXR-1020, FXR-1030 (manufactured by Fujikasei Kogyo Co., Ltd.), and the like. These may be used alone or in combination of two or more.

[0049] (C) The particle size of the amine-based latent curing agent preferably is 0.9 or more. The particle size of the (C) amine-based latent curing agent is more preferably 0.92 or more, and even more preferably 0.94 or more. The upper limit of the particle size of the (C) amine-based latent curing agent is not particularly limited, and for example, it is 1.0. When the particle size of the (C) amine-based latent curing agent is within the above range, the solvent resistance, moisture resistance, and filler resistance tend to be good after encapsulation.

[0050] Here, the particle size is a value obtained by the following method. Using a flow-type particle image analyzer FPIA-3000S (manufactured by Spectris Co., Ltd.), the particle size can be determined by measuring a dispersion liquid in which various curing agents obtained during the manufacturing process are dispersed at 0.5% by mass in cyclohexane. Encapsulated ones are regarded as being uniformly encapsulated, and the particle size of the curing agent is used as it is. The closer the particle size is to 1, the closer it is to a perfect sphere.

[0051] (C) The method for controlling the particle size of the amine-based latent curing agent within the above range is not particularly limited. For example, a method of surface-modifying the (C) amine-based latent curing agent is effective. Other examples include methods of mechanically rounding the particles or performing hot air treatment.

[0052] (Encapsulated curing agent) In the epoxy resin composition of this embodiment, the (C) amine-based latent curing agent is preferably an encapsulated curing agent in the form of a capsule, and more preferably a microcapsule-type curing agent.

[0053] In the epoxy resin composition of this embodiment, since the (C) amine-based latent curing agent is encapsulated, the curing agent can be physically isolated, improving stability.

[0054] Examples of the encapsulated (C) amine-based latent curing agent include, but are not limited to, epoxy-based, acrylic-based, latex-based, urethane-based, and silica-based ones.

[0055] (C) As a method for encapsulating an amine-based latent curing agent, examples include, but are not limited to, the following methods (1) to (3).

[0056] (1): A method in which a capsule component and particles of a curing agent are dissolved and dispersed in a solvent as a dispersion medium, and then the solubility of the capsule component in the dispersion medium is decreased to precipitate a capsule on the surface of the particles of the curing agent for an epoxy resin. (2): A method in which particles of a curing agent are dispersed in a dispersion medium, and a material for forming the above capsule is added to this dispersion medium and precipitated on the particles of the curing agent. (3): A method in which raw material components for forming a capsule are added to a dispersion medium, and a shell-forming material is generated there using the surface of the particles of the curing agent as a reaction site.

[0057] Here, the methods (2) and (3) are preferable because the reaction and coating can be carried out simultaneously.

[0058] The method for separating the capsule-type curing agent from the dispersion medium after forming the capsule by the methods (2) and (3) is not particularly limited, but it is preferable to separate and remove both the unreacted raw materials and the dispersion medium after forming the capsule. Examples of such a method include a method of removing the dispersion medium and the unreacted capsule-forming material by filtration.

[0059] After removing the dispersion medium, it is preferable to wash the capsule-type curing agent. Thereby, the unreacted capsule-forming material adhering to the surface of the capsule-type curing agent can be removed.

[0060] The washing method is not particularly limited. For example, when separating the residue by filtration, it can be washed using a solvent that does not dissolve the dispersion medium or the capsule-type curing agent.

[0061] After filtration and washing, when the capsule-type curing agent is dried, a powdery microcapsule-type curing agent can be obtained. The drying method is not particularly limited, but it is preferably dried at a temperature equal to or lower than the melting point or softening point of the curing agent. For example, drying under reduced pressure can be mentioned.

[0062] By making the capsule-type curing agent powdery, the compounding operation with the epoxy resin can be easily applied. Further, when an epoxy resin is used as the dispersion medium, it is preferable because a liquid resin composition composed of an epoxy resin and a microcapsule-type curing agent for epoxy resin can be obtained simultaneously with capsule formation.

[0063] Incidentally, the thickness of the capsule film can be controlled by the amount of the encapsulating agent and the reaction conditions. If the capsule film is too thin, the storage stability, moisture resistance, and filler resistance tend to be difficult to achieve. The amount of the encapsulating agent is not particularly limited as long as the stability can be ensured. The capsule formation reaction is usually carried out in a temperature range of -10°C to 150°C, preferably 0°C to 100°C, and usually in a reaction time of 10 minutes to 72 hours, preferably 30 minutes to 24 hours.

[0064] [(D) Filler] The epoxy resin composition of this embodiment preferably contains a (D) filler.

[0065] The (D) filler is not particularly limited as long as the effects of the present invention can be achieved. From the viewpoints of the coefficient of thermal expansion and thermal conductivity, inorganic fillers (inorganic fillers) and inorganic fillers treated with a silane coupling agent can be mentioned. From the viewpoints of improving the adhesive strength and crack resistance, one or more selected from organic fillers can be mentioned.

[0066] The epoxy resin composition of this embodiment can adjust the coefficient of thermal expansion by containing an inorganic filler and tends to contribute to the improvement of heat resistance and moisture resistance.

[0067] Examples of the inorganic filler include, but are not limited to, silicates such as talc, calcined clay, uncalcined clay, mica, and glass; oxides such as silicon oxide including titanium oxide, aluminum oxide (alumina), fused silica (fused spherical silica, fused crushed silica), synthetic silica, and crystalline silica; carbonates such as calcium carbonate, magnesium carbonate, and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; sulfates such as barium sulfate and calcium sulfate; sulfites such as calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; and nitrides such as aluminum nitride, boron nitride, and silicon nitride.

[0068] Among these, from the viewpoint of improving heat resistance, moisture resistance, and strength, fused silica, crystalline silica, and synthetic silica powder are preferable, and any one of silicon oxide, aluminum oxide, and boron nitride is also preferable.

[0069] By using such a filler, the epoxy resin composition of this embodiment can suppress the coefficient of thermal expansion, and thus improvement in the thermal cycle test and the like can be expected.

[0070] The above-mentioned (D) filler may be used alone or in combination of two or more.

[0071] The shape of the (D) filler is not particularly limited, and may be, for example, any of amorphous, spherical, and flaky forms.

[0072] When an inorganic filler is used as the (D) filler, the content of the inorganic filler in the epoxy resin composition of this embodiment is not particularly limited, but is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 85% by mass or less, based on the total amount (100% by mass) of the epoxy resin composition.

[0073] By setting the content of the inorganic filler to be equal to or greater than the above lower limit value, the epoxy resin composition of this embodiment tends to achieve an excellent low coefficient of thermal expansion. Further, by setting the content of the inorganic filler to be equal to or less than the above upper limit value, the epoxy resin composition of this embodiment tends to further suppress the increase in elastic modulus.

[0074] The inorganic filler is preferably surface-treated with a silane coupling agent.

[0075] Although the performance of the silane coupling agent can be exhibited by including it in the epoxy resin composition of this embodiment, surface treatment of the inorganic filler with the silane coupling agent tends to further reduce the viscosity.

[0076] Examples of the silane coupling agent include, but are not limited to, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)-3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, and other silane coupling agents.

[0077] Among these, from the viewpoint of adhesion strength, a silane coupling agent having a polymerizable functional group is preferable.

[0078] The organic filler has a function as an impact relaxation agent having stress relaxation properties.

[0079] By containing an organic filler, the epoxy resin composition of the present embodiment can further improve the adhesiveness with various connection members, and also tends to suppress the generation and progression of fillet cracks.

[0080] Examples of the organic filler include, but are not limited to, acrylic resin, silicone resin, butadiene rubber, polyester, polyurethane, polyvinyl butyral, polyarylate, polymethyl methacrylate, acrylic rubber, polystyrene, NBR, SBR, silicone-modified resin, and organic fine particles of copolymers containing these as components.

[0081] From the viewpoint of improving adhesiveness, examples of the organic fine particles include (meth)acrylate alkyl-butadiene-styrene copolymer, (meth)acrylate alkyl-silicone copolymer, silicone-(meth)acrylic copolymer, a complex of silicone and (meth)acrylic acid, a complex of (meth)acrylate alkyl-butadiene-styrene and silicone, and a complex of (meth)acrylate alkyl and silicone. It is preferable to use these.

[0082] As the organic filler, organic fine particles having a core-shell type structure and different compositions in the core layer and the shell layer can also be used.

[0083] Examples of the core-shell type organic fine particles include particles obtained by grafting acrylic resin onto silicone-acrylic rubber as the core, and particles obtained by grafting acrylic resin onto an acrylic copolymer.

[0084] Due to the reduction in elastic modulus caused by the inclusion of the core-shell type organic fine particles, the stress generated in the fillet portion is reduced, and the generation of fillet cracks tends to be suppressed. Further, when fillet cracks occur, the included core-shell type organic fine particles act as a stress relaxant, and the progression of fillet cracks tends to be suppressed.

[0085] As the constituent material of the core layer, a material having excellent flexibility is preferably used. Examples of the constituent material of the core layer include, but are not limited to, silicone-based elastomers, butadiene-based elastomers, styrene-based elastomers, acrylic-based elastomers, polyolefin-based elastomers, and silicone / acrylic composite elastomers.

[0086] On the other hand, as the constituent material of the shell layer, a material having excellent affinity for other components of the semiconductor resin encapsulant, particularly excellent affinity for epoxy resins, is preferably used. Examples of the constituent material of the shell layer include, but are not limited to, acrylic resins and epoxy resins. Among these, acrylic resins are preferable from the viewpoint of affinity for other components of the encapsulant, particularly affinity for epoxy resins.

[0087] (D) When an organic filler is used as the filler, the content of the organic filler in the epoxy resin composition of the present embodiment is preferably 1 to 20% by mass, more preferably 2 to 18% by mass, and still more preferably 3 to 16% by mass with respect to the total amount (100% by mass) of the epoxy resin composition.

[0088] When the content of the organic filler in the epoxy resin composition of the present embodiment is equal to or higher than the lower limit value, stress relaxation acts, and there is a tendency to obtain an effect of improving the adhesive strength.

[0089] When the content of the organic filler in the epoxy resin composition of the present embodiment is equal to or lower than the upper limit value, there is a tendency to obtain an effect of heat reflow resistance.

[0090] [Other Components] The epoxy resin composition of the present embodiment may contain stabilizers, flame retardants, etc. as other components as long as the effects of the present invention can be achieved.

[0091] The stabilizer is not particularly limited, and examples thereof include boric acid and cyclic borate ester compounds for improving storage stability. These may be used alone or in combination of two or more.

[0092] The cyclic borate ester compound is one in which boron is contained in a cyclic structure. The cyclic borate ester compound is preferably 2,2'-oxybis(5,5'-dimethyl-1,3,2-oxaborinane).

[0093] The flame retardant is not particularly limited, and examples thereof include brominated flame retardants, phosphorus-based flame retardants, and inorganic flame retardants.

[0094] These may be used alone or in combination of two or more.

[0095] Examples of the brominated flame retardant include, but are not particularly limited to, tetrabromophenol. Examples of the phosphorus-based flame retardant include, but are not particularly limited to, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and its epoxy derivatives, triphenylphosphine and its derivatives, phosphate esters, condensed phosphate esters, and phosphazene compounds. Examples of the nitrogen-based flame retardant include, but are not particularly limited to, guanidine-based flame retardants, phenols containing a triazine structure, melamine polyphosphate, and isocyanuric acid. Examples of the inorganic flame retardant compound include, but are not particularly limited to, magnesium hydroxide and aluminum hydroxide, and magnesium hydroxide is preferred from the viewpoint of heat resistance.

[0096] The content of the flame retardant is not particularly limited, but is preferably 5% by mass or more and 200% by mass or less, more preferably 10% by mass or more and 100% by mass or less based on the mass (100% by mass) of the epoxy resin composition.

Examples

[0097] The present invention will be described more specifically by way of examples and comparative examples, but the present invention is not limited thereto.

[0098] [Production of (C) amine-based latent curing agent] The production methods of the (C) amine-based latent curing agents used in the examples and comparative examples are shown below. (Production Example 1) 188 parts by mass of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation: trade name "jER828EL") and 110 parts by mass of 2-ethyl-4-methylimidazole were reacted at 80 °C in 400 parts by mass of a 1:1 mixed solvent of n-butanol and toluene. Thereafter, the excess amine was distilled off together with the solvent under reduced pressure to obtain a solid block-shaped curing agent for epoxy resin at 25 °C. Next, the block-shaped curing agent for epoxy resin was pulverized with a jet mill to obtain particles having a specific surface area value of 3.63 m 2 / g, a sieve residue average particle size D50 of 2.40 μm, a D99 / D50 of 8.6, and a particle size degree of 0.86 (pulverized product, curing agent for epoxy resin 1 (amine-based latent curing agent)). 100 parts by mass of curing agent for epoxy resin 1 was uniformly dispersed in 200 parts by mass of hexane, 30 parts by mass of an encapsulating agent (manufactured by Tosoh Corporation: trade name "MR-400") was added, and the reaction was continued for 3 hours with stirring at 50 °C to obtain curing agent for epoxy resin 2 (microcapsule type amine-based latent curing agent).

[0099] (Production Example 2) Using the curing agent for epoxy resin 1 and using a Cryptron Orb manufactured by Earth Technica Co., Ltd., in an environment of a temperature of 10 °C and a humidity of 30%, a shape correction treatment was performed at a rotational speed of 13,500 rpm, a supply rate of 10 kg / hour, and an air volume of 3 m 3 / min, a cyclone type collector and a bag filter were attached to adjust the specific surface area value, and a curing agent for epoxy resin having a specific surface area value of 2.67 m 2 / g, a D50 of 3.1 μm, a D99 / D50 of 4.5, and a particle size degree of 0.96 was produced by a classification operation using a classifier to obtain curing agent for epoxy resin 3. 100 parts by mass of a curing agent 3 for epoxy resin was uniformly dispersed in 200 parts by mass of hexane, 20 parts by mass of a encapsulating agent (manufactured by Tosoh Corporation: trade name "Coronate T100") was added, and the reaction was continued for 3 hours while stirring at 50°C to obtain a curing agent 4 for epoxy resin (microcapsule-type amine-based latent curing agent).

[0100] (Production Example 3) 188 parts by mass of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation: trade name "jER828EL") and 110 parts by mass of 2-ethyl-4-methylimidazole were reacted at 80°C in 400 parts by mass of a 1:1 mixed solvent of n-butanol and toluene. Then, excess amine was distilled off together with the solvent under reduced pressure, and then heated to 150°C. 100 parts by mass of powdered amine triethylenediamine (manufactured by Tosoh Corporation: trade name "TEDA") was added, and after sufficient mixing, it was cooled to obtain a solid block-shaped curing agent for epoxy resin at 25°C. Next, the block-shaped curing agent for epoxy resin was pulverized with a jet mill, and further using a Cryptron Orb manufactured by Earth Technica Co., Ltd., in an environment of a temperature of 10°C and a humidity of 30%, a rotation speed of 13,500 rpm, a supply speed of 10 kg / hour, and an air volume of 3 m 3 / min, a shape correction treatment was performed, a cyclone type collector and a bag filter were attached to adjust the specific surface area value, and a curing agent for epoxy resin having a specific surface area value of 1.98 m 2 / g, a D50 of 3.6 μm, a D99 / D50 of 4.5, and a particle size degree of 0.95 was produced by a classification operation using a classifier to obtain a curing agent 5 for epoxy resin. 100 parts by mass of a curing agent 5 for epoxy resin was uniformly dispersed in 200 parts by mass of hexane, 15 parts by mass of an encapsulating agent (manufactured by Tosoh Corporation: trade name "Coronate T65") was added, and the reaction was continued for 3 hours while stirring at 50°C to obtain a curing agent 6 for epoxy resin (microcapsule-type amine-based latent curing agent). In this example, the particle size was measured as follows. Using a flow-type particle image analyzer FPIA-3000S (manufactured by Spectris Co., Ltd.), the particle size was determined by measuring a dispersion obtained by dispersing various curing agents obtained during the manufacturing process in cyclohexane at 0.5% by mass. Encapsulated materials were regarded as uniformly encapsulated, and the particle size of the curing agent was used as it was.

[0101] The measurement methods for the physical properties and characteristics used in the examples and comparative examples are shown below. (1) Flexural modulus For the cured product described later, using a measuring device RSA-G2 manufactured by TA Instruments, the flexural modulus at a predetermined temperature (-25°C and 25°C) was measured in accordance with JIS K7244-5.

[0102] (2) Residual heat release amount by differential scanning calorimetry (DSC) measurement Regarding the epoxy resin compositions immediately after compounding obtained in the examples and comparative examples, using a DSC measuring device Q2000 manufactured by TA Instruments, the total heat release amount obtained by measuring from 25 to 250°C at 10°C / min was taken as 100%, and the 100 fraction of the total heat release amount obtained by measuring the cured product described later under the same conditions was determined. The determined value was taken as the residual heat release amount (%).

[0103] (3) Differential scanning calorimetry (DSC) measurement Regarding the epoxy resin compositions immediately after compounding obtained in the examples and comparative examples, using a DSC measuring device Q2000 manufactured by TA Instruments, after heating to 80°C at 100°C / min, isothermal measurement was performed for 2 hours in a nitrogen atmosphere. The time point when it reached 80°C was taken as the measurement start time, and the time until the heat release peak top (when the heat flow rate was at the peak top) was measured.

[0104] (4) Storage stability The viscosity (n1) of the epoxy resin composition immediately after compounding obtained in the examples and comparative examples was measured at 23°C using a BH-type viscometer. Also, the epoxy resin composition immediately after compounding obtained in the examples and comparative examples was placed in a sealed container with a lid, and after storing at 30°C for 48 hours, the viscosity (n2) was similarly measured. The viscosities (n1 and n2) of both obtained were compared, and the viscosity magnification (n2 / n1) was determined.

[0105] (5) Thermal cycling test The epoxy resin compositions obtained in the examples and comparative examples were applied onto a silicon wafer to a thickness of 500 μm and cured at 80°C for 30 minutes to form a cured product on the silicon wafer. Then, the silicon wafer on which the cured product was formed was cut into 5 cm × 5 cm pieces as test pieces, and a thermal cycling test from -40°C to +100°C was carried out up to 3000 cycles in accordance with JIS C60068. The presence or absence of cracks in the cured product was observed every 1000 cycles. Those without cracks up to 3000 cycles were rated as ◎, those without cracks up to 2000 cycles but with cracks up to 3000 cycles were rated as 〇, those without cracks up to 1000 cycles but with cracks up to 2000 cycles were rated as △, and those with cracks up to 1000 cycles were rated as ×.

[0106] (6) Damp heat test (tensile shear adhesion strength retention rate) Regarding the cured product described later, in accordance with JIS K6850, the initial tensile shear adhesion strength (s1) immediately after curing was measured, and after leaving it in an environment of 30°C × 90% RH for 168 hours after curing, the tensile shear adhesion strength (s2) was similarly measured. The adhesion strengths of both were measured. The adhesion strengths of both were compared, and the tensile shear adhesion strength retention rate (s2 / s1) was determined. It was evaluated that the closer the tensile shear adhesion strength retention rate was to 1 times, the better the adhesiveness. Sumika Super E6007LHF (manufactured by Sumitomo Chemical Co., Ltd.) was used as the adherend.

[0107] [Examples 2 to 6 and Reference Examples 1 to 2 , as well as Comparative Examples 1 to 5] (Preparation of epoxy resin composition) At the compounding ratios shown in Table 1 below, after weighing each of the components (A) to (E) described below, stirring was performed for 2 minutes and defoaming was performed for 3 minutes using a non-bubbling kneader, and they were mixed to prepare a liquid epoxy resin composition at 25°C. For the prepared epoxy resin composition, each of the above measurements was carried out. The measurement results are shown in Table 1. The compounding amounts of the components (A) to (E) in Table 1 are shown in parts by mass when the total amount of the component (A) and the component (B) is 100 parts by mass. (Preparation of cured product) The prepared epoxy resin composition was poured into a mold made of Teflon (registered trademark) and cured in a heating furnace at 80°C for 30 minutes. After curing, the Teflon mold was removed to obtain a cured plate with a thickness of 2 mm. From the obtained cured plate, samples (cured products) of the size conforming to each of the above measurements were cut out using a step cutter, and each of the above measurements was carried out. The measurement results are shown in Table 1.

[0108] [(A) Liquid epoxy resin] A-1: BE-186EL (manufactured by Changchun Synthetic Resin Co., Ltd., epoxy equivalent: 186, viscosity at 25°C: 13.0 Pa·s) A-2: BFE170 (manufactured by Changchun Synthetic Resin Co., Ltd., epoxy equivalent: 170, viscosity at 25°C: 5.4 Pa·s) A-3: AER9000 (manufactured by Asahi Kasei Corporation, flexible epoxy resin; epoxy equivalent: 380, viscosity at 25°C: 900 mPa·s (0.9 Pa·s)) A-4: YED216L (manufactured by Mitsubishi Chemical Corporation, flexible epoxy resin; epoxy equivalent: 160, viscosity at 25°C: 15 mPa·s (0.015 Pa·s))

[0109] [(B) Thiol compound] B-1: BPADT (manufactured by Ajinomoto Fine-Techno Co., Inc., thiol equivalent: 188 g / eq, ester-free) B-2: TMPIA (manufactured by Ajinomoto Fine-Techno Co., Inc., thiol equivalent: 117 g / eq, ester-free) B-3: TS-G (manufactured by Shikoku Chemicals Corporation, thiol equivalent: 108 g / eq, ester-free) B-4: PEPT (manufactured by SC Organic Chemistry Co., Ltd., thiol equivalent: 124 g / eq, ester-free) B-5: PEMP (manufactured by SC Organic Chemistry Co., Ltd., thiol equivalent: 122 g / eq, ester-containing) The structures of each thiol compound B-1 to B-5 are as follows.

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

[0110] [(C) Amine-based latent curing agent] C-1: Curing agent 1 for epoxy resin C-2: Curing agent 2 for epoxy resin C-3: Curing agent 4 for epoxy resin C-4: Curing agent 6 for epoxy resin C-5: PN23J (manufactured by Ajinomoto Fine-Techno Co., Inc.) C-6: HXA5945HP (manufactured by Asahi Kasei Co., Ltd., amine-based latent curing agent)

[0111] [(D) Filler] D-1: Amino-silane-treated SO-C2 (manufactured by Admatechs Co., Ltd.)

[0112] [(E) Other components] E-1: L-07N (manufactured by Shikoku Kasei Co., Ltd., borate ester compound)

[0113]

Table 1

[0114] From the results in Table 1, the epoxy resin composition satisfying specific conditions had good results in the thermal cycle test and adhesiveness.

Industrial Applicability

[0115] Since the epoxy resin composition of the present invention is excellent in thermal cycle and adhesiveness, it has industrial applicability as an adhesive and a liquid encapsulant for various electronic components.

Claims

1. An epoxy resin composition containing (A) a liquid epoxy resin, (B) a thiol compound, and (C) an amine-based latent curing agent (excluding the reaction product of the amine compound represented by the following formula (a) and the epoxy resin), being liquid at 25°C, and satisfying the following conditions (1) to (4): An epoxy resin composition in which (C) the amine-based latent curing agent contains an imidazole compound; (1) The cured product cured at 80°C for 30 minutes has a flexural modulus at -25°C of 0.1 GPa to 8.0 GPa; (2) The cured product cured at 80°C for 30 minutes has a flexural modulus at 25°C of 0.05 GPa to 4.0 GPa; (3) The cured product cured at 80°C for 30 minutes has a residual heat generation amount of 15% or less when measured with a differential scanning calorimeter (DSC); (4) The viscosity magnification (n2 / n1) of the viscosity (n2) after storing at 30°C for 48 hours with respect to the viscosity (n1) immediately after blending is 0.9 times or more and 1.3 times or less. 【Chemical 1】 (In formula (a), R 1 ' and R 2 ' each independently represent an optionally substituted alkyl group having 1 to 8 carbon atoms, an optionally substituted cycloalkyl group, or an optionally substituted benzyl group, X and Z each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, an optionally substituted aryl group, an optionally substituted cycloalkyl group, or an optionally substituted benzyl group, n represents an integer of 0 or more and 8 or less, and m represents an integer of 0 or more and 4 or less.)

2. The epoxy resin composition according to claim 1, further satisfying the following condition (5): (5) When analyzing the epoxy resin composition in a nitrogen atmosphere with a differential scanning calorimeter (DSC) at an isothermal temperature of 80°C, the time from reaching 80°C to reaching the peak top of the heat flow rate is 20 minutes or less.

3. The epoxy resin composition according to claim 1 or 2, wherein (A) the liquid epoxy resin contains (A1) a flexible epoxy resin.

4. The epoxy resin composition according to any one of claims 1 to 3, wherein the particle size degree of (C) the amine-based latent curing agent is 0.9 or more.

5. The epoxy resin composition according to any one of claims 1 to 4, wherein (C) the amine-based latent curing agent is of the microcapsule type.

6. The epoxy resin composition according to any one of claims 1 to 5, further containing (D) a filler.

7. The epoxy resin composition according to any one of claims 1 to 6, wherein (B) the thiol compound contains an ester-free thiol compound.

8. The epoxy resin composition according to claim 7, wherein (B) the thiol compound contains a compound represented by the following formula (1) and / or (2). [Chemical Formula 2] [Chemical Formula 3] (In formulas (1) and (2), R 1 ~R 5 each independently represents a linear or branched divalent hydrocarbon group or hetero group having 1 to 6 carbon atoms.)

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