WO2025205208A1 - Polyester elastomer-containing composition and electric/electronic component-sealed body - Google Patents

Abstract

Provided are: a polyester elastomer-containing composition capable of forming an electric/electronic component-sealed body that exhibits a small change after ATF immersion, thus has excellent ATF resistance, has excellent durability and does not exhibit deterioration in mechanical characteristics even in a hot humid environment of 85% and 85°C, and has excellent adhesion to base materials; and an electric/electronic component-sealed body using the polyester elastomer-containing composition. The present invention pertains to a polyester elastomer-containing composition comprising: a polyester elastomer (a) having a hard segment (a-1) having a crystalline aromatic polyester and a soft segment (a-2) containing an aliphatic polycarbonate; an acrylic elastomer (b); and an epoxy resin (c).

Description

Polyester elastomer-containing composition and sealed electrical/electronic component

The present invention relates to sealed electrical and electronic components sealed with a polyester elastomer-containing composition, and to a polyester elastomer-containing composition suitable for this application.

Electrical and electronic components widely used in automobiles and electrical appliances must be electrically insulated from the outside in order to achieve their intended use, and there is a need for a sealing method that can accurately conform to the shape of the electrical and electronic component and leave no unfilled areas. Hot melt resins, which can be sealed by simply heating and melting them, reduce their viscosity and solidify to form a sealed body simply by cooling after sealing, making them highly productive. They also have excellent features such as the ability to easily recycle components by heating and melting and removing the resin, making them well suited for sealing electrical and electronic components.

In automotive applications, the number of electrical and electronic components installed has been increasing in recent years due to the trend toward electrification and automation. With the development of electric vehicles (EVs), the number of electrical and electronic components installed continues to increase, creating a demand for heat resistance in electrical and electronic component sealing materials. Patent Document 1 discloses an electrical and electronic component sealing resin composition containing a polyester resin with specific composition and physical properties, a fluororesin, and an epoxy resin, which maintains high adhesion even when exposed to high temperatures of 150°C for long periods of time.

JP 2013-112771 A

Furthermore, today's electrical and electronic components are required to be durable against automatic transmission fluid (ATF). Electric vehicles use motors as engine replacements to suppress heat generation, and ATF cooling is used as an oil cooling method, so motor control and the electrical and electronic components located nearby must be ATF resistant. While Patent Document 1 is thought to have excellent ATF resistance, it contains a fluororesin that has adverse adhesive properties, raising concerns about adhesion to other substrates.

The objective of the present invention is to provide a polyester elastomer-containing composition that undergoes little change after immersion in ATF, i.e., has excellent ATF resistance, and is capable of forming sealed electrical and electronic components that exhibit excellent durability and excellent adhesion to various substrates without deterioration in mechanical properties even in a humid and hot environment of 85°C and 85% humidity, and also to provide sealed electrical and electronic components using the same.

The present invention, which has achieved the above object, is as follows.
[1] A polyester elastomer (a) having a hard segment (a-1) containing a crystalline aromatic polyester and a soft segment (a-2) containing an aliphatic polycarbonate;
A polyester elastomer-containing composition comprising an acrylic elastomer (b) and an epoxy resin (c).
[2] The polyester elastomer-containing composition according to [1], further comprising an antioxidant (d1) and/or a light stabilizer (d2).
[3] The polyester elastomer-containing composition according to [1] or [2], wherein the mass ratio of the hard segment (a-1) to the soft segment (a-2): (a-1)/(a-2) is 80/20 to 20/80.
[4] The polyester elastomer-containing composition according to any one of [1] to [3], wherein the acrylic elastomer (b) is 8 to 280 parts by mass per 100 parts by mass of the polyester elastomer (a).
[5] The polyester elastomer-containing composition according to any one of [1] to [4], wherein the epoxy resin (c) is 0.5 to 30 parts by mass per 100 parts by mass of the polyester elastomer (a).
[6] The polyester elastomer-containing composition according to any one of [1] to [5], wherein the carboxylic acid constituting the polyester of the hard segment (a-1) contains terephthalic acid and/or naphthalenedicarboxylic acid, and the total amount of terephthalic acid and naphthalenedicarboxylic acid is 70 mol% or more in 100 mol% of all carboxylic acids constituting the polyester of the hard segment (a-1).
[7] The polyester elastomer-containing composition according to any one of [1] to [6], wherein the glycol component constituting the polyester of the hard segment (a-1) contains an alkylene glycol having 2 to 8 carbon atoms and having no side chain, and the amount of the alkylene glycol having 2 to 8 carbon atoms and having no side chain is 90 mol % or more of 100 mol % of all glycol components constituting the polyester of the hard segment (a-1).
[8] The polyester elastomer-containing composition according to any one of [1] to [7], wherein the components constituting the polyester of the hard segment (a-1) contain butylene terephthalate units and/or butylene naphthalate units, and the total amount of the butylene terephthalate units and butylene naphthalate units is 90 mass% or more in 100 mass% of all components constituting the polyester of the hard segment (a-1).
[9] The polyester elastomer-containing composition according to any one of [1] to [8], wherein the soft segment (a-2) is an aliphatic polycarbonate diol having an aliphatic diol residue, and the amount of the aliphatic diol residue having 2 to 12 carbon atoms in 100% by mass of the aliphatic diol residue is 90% by mass or more.
[10] The acrylic elastomer (b) is composed of a hard segment (b-1) and a soft segment (b-2), and contains a triblock copolymer having one block constituting the hard segment (b-1) on each side of one block constituting the soft segment (b-2),
The polyester elastomer-containing composition according to any one of [1] to [9], wherein the proportion of the triblock copolymer in 100% by mass of the acrylic elastomer (b) is 60% by mass or more.
[11] The polyester elastomer-containing composition according to [10], wherein the mass ratio ((b-1)/(b-2)) of the hard segment (b-1) to the soft segment (b-2) is 15/85 to 85/15.
[12] The polyester elastomer-containing composition according to [10] or [11], wherein the vinyl monomer constituting the hard segment (b-1) is at least one selected from the group consisting of methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the monomer constituting the soft segment (b-2) contains 70 mass% or more of at least one selected from the group consisting of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, n-hexyl acrylate, ethylhexyl acrylate, n-heptyl acrylate, and n-octyl acrylate.
[13] The polyester elastomer-containing composition according to any one of [2] to [12], wherein the polyester elastomer-containing composition contains the antioxidant (d) in an amount of 0.5 to 10 parts by mass per 100 parts by mass of the polyester elastomer (a).
[14] Further comprising a polycarbodiimide resin (e),
[14] The polyester elastomer-containing composition according to any one of [1] to [13], wherein the amount of the polycarbodiimide resin (e) is 0.1 to 5 parts by mass per 100 parts by mass of the polyester elastomer (a).
[15] The polyester elastomer-containing composition according to any one of [1] to [14], which is used for sealing electrical and electronic components.
[16] A sealed electrical/electronic component sealed with the polyester elastomer-containing composition according to any one of [1] to [14].
[17] Use of the polyester elastomer-containing composition according to any one of [1] to [14] in a sealed electrical/electronic component.

The polyester elastomer-containing composition of the present invention has excellent ATF resistance, durability in humid and hot environments, and adhesion to various substrates. In a preferred embodiment, the present invention can also improve long-term reliability in high-temperature environments of 150°C.

[Polyester elastomer (a)]
The polyester elastomer used in the present invention is a thermoplastic elastomer containing a hard segment (a-1) and a soft segment (a-2). The hard segment (a-1) contains a crystalline aromatic polyester. In the present invention, a crystalline aromatic polyester refers to a polyester containing 35 mol% or more of an aromatic dicarboxylic acid component, when the total constituent components of the polyester are taken as 100 mol%, and having a melting point when measured by the method described in the Examples. When the total constituent components of the polyester are taken as 100 mol%, the proportion of the aromatic dicarboxylic acid component is preferably 40 mol% or more, and more preferably 50 mol% or more. Conventional aromatic dicarboxylic acids are widely used as the aromatic dicarboxylic acid constituting the polyester of the hard segment (a-1). The primary aromatic dicarboxylic acid is preferably terephthalic acid or naphthalenedicarboxylic acid (among its isomers, 2,6-naphthalenedicarboxylic acid is preferred), with terephthalic acid being more preferred. Of the total carboxylic acids constituting the polyester of the hard segment (a-1), the combined amount of terephthalic acid and naphthalenedicarboxylic acid is preferably 70 mol% or more, and more preferably 80 mol% or more. Examples of other dicarboxylic acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride, and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These are used within a range that does not significantly lower the melting point of the resin, and the amount thereof is preferably 30 mol % or less, and more preferably 20 mol % or less, of the total carboxylic acid components.
The proportion of the aromatic dicarboxylic acid component contained in the crystalline aromatic polyester is determined from the amount charged and various analyses such as ¹ H-NMR analysis and ¹³ C-NMR analysis.

Furthermore, in the thermoplastic polyester elastomer used in the present invention, the glycol component constituting the polyester of the hard segment (a-1) preferably comprises an aliphatic or alicyclic diol as the main component, and the total amount of aliphatic and alicyclic diols is preferably 90 to 100 mol%, and more preferably 95 to 100 mol%, out of 100 mol% of the glycol component constituting the polyester of the hard segment (a-1). As the aliphatic diol or alicyclic diol, general aliphatic or alicyclic diols are widely used, and although there are no particular limitations, it is desirable that they are primarily alkylene glycols having 2 to 8 carbon atoms. Furthermore, alkylene glycols without side chains are preferred. The glycol component constituting the polyester of the hard segment (a-1) preferably contains an alkylene glycol having 2 to 8 carbon atoms and no side chains. Of the total glycol components constituting the polyester of the hard segment (a-1), the amount of alkylene glycols having 2 to 8 carbon atoms and no side chains is preferably 90 to 100 mol %, and more preferably 95 to 100 mol %. Specific examples of alkylene glycols having 2 to 8 carbon atoms include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. Of these, ethylene glycol or 1,4-butanediol is preferred for imparting heat resistance.

The components constituting the polyester of the hard segment (a-1) above are preferably those containing butylene terephthalate units (units consisting of terephthalic acid and 1,4-butanediol) or butylene naphthalate units (units consisting of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) from the viewpoints of physical properties, moldability, and cost performance. Of 100% by mass of the components constituting the polyester of the hard segment (a-1), the total amount of butylene terephthalate units and butylene naphthalate units is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and it is particularly preferable that the butylene terephthalate units be within these ranges.

Furthermore, when an aromatic polyester suitable as the polyester constituting the hard segment (a-1) in the thermoplastic polyester elastomer (a) used in the present invention is produced in advance and then copolymerized with the soft segment component, the aromatic polyester can be easily obtained using conventional polyester production methods. Furthermore, such polyesters preferably have a number average molecular weight of 10,000 to 40,000.

The soft segment (a-2) of the thermoplastic polyester elastomer (a) used in the present invention contains an aliphatic polycarbonate. The amount of aliphatic polycarbonate in 100% by mass of the soft segment (a-2) is preferably 90 to 100% by mass, and more preferably 95 to 100% by mass. The aliphatic polycarbonate is preferably an aliphatic polycarbonate diol having aliphatic diol residues, and more preferably contains aliphatic diol residues primarily having 2 to 12 carbon atoms. The amount of aliphatic diol residues having 2 to 12 carbon atoms in 100% by mass of the aliphatic diol residues is preferably 90 to 100% by mass, and more preferably 95 to 100% by mass. Examples of aliphatic diols having 2 to 12 carbon atoms include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol. Aliphatic diols having 5 to 12 carbon atoms are particularly preferred in terms of the flexibility and cold resistance of the resulting thermoplastic polyester elastomer (a). These components may be used alone, or two or more may be used in combination as necessary, based on the examples described below.

The aliphatic polycarbonate diol constituting the soft segment (a-2) of the thermoplastic polyester elastomer (a) of the present invention preferably has a low melting point (e.g., 70°C or below) and a low glass transition temperature, and such aliphatic polycarbonate diols have excellent cold resistance. The melting point is, for example, 0 to 70°C, and may be 10 to 60°C, and the glass transition temperature is, for example, -90 to -40°C, and may be -80 to -45°C. Cold resistance refers to the property of an encapsulant formed from the composition not cracking at low temperatures, and the evaluation temperature for cold resistance is, for example, -40°C. Having the glass transition temperature of the soft segment (a-2) below the cold resistance evaluation temperature suppresses changes in physical properties such as tensile elongation, preventing cracking and other problems. Aliphatic polycarbonate diols made from 1,6-hexanediol, which are generally used to form the soft segments of thermoplastic polyester elastomers, have a low glass transition temperature of around -60°C and a melting point of around 50°C, resulting in good cold resistance. Additionally, aliphatic polycarbonate diols obtained by copolymerizing an appropriate amount of, for example, 3-methyl-1,5-pentanediol with the above-mentioned aliphatic polycarbonate diols have a slightly higher glass transition temperature than the original aliphatic polycarbonate diol, but a lower melting point or the resulting product is amorphous, resulting in good cold resistance. Furthermore, aliphatic polycarbonate diols made from 1,9-nonanediol and 2-methyl-1,8-octanediol, for example, have a melting point of around 30°C and a sufficiently low glass transition temperature of around -70°C, resulting in good cold resistance.

The soft segment (a-2) containing an aliphatic polycarbonate can be formed using an aliphatic polycarbonate diol. The reduced viscosity of an aliphatic polycarbonate diol suitable for forming the aliphatic polycarbonate segment is preferably 0.5 dl/g or higher, more preferably 0.8 dl/g or higher, and even more preferably 0.85 dl/g or higher. Furthermore, the reduced viscosity of an aliphatic polycarbonate diol suitable for forming the aliphatic polycarbonate segment is preferably 1.3 dl/g or lower, more preferably 1.2 dl/g or lower, and even more preferably 1.1 dl/g or lower. In other words, the reduced viscosity of the aliphatic polycarbonate diol is preferably 0.5 to 1.3 dl/g, more preferably 0.8 to 1.2 dl/g, and even more preferably 0.85 to 1.1 dl/g. If the reduced viscosity of the polycarbonate diol is too low, the long-term heat resistance of the polyester elastomer tends to be significantly reduced. On the other hand, it is difficult to reproducibly produce polycarbonate diol with a high reduced viscosity of 1.3 dl/g or more, which is disadvantageous in terms of cost.

There are no particular restrictions on the method for adjusting the reduced viscosity of the polycarbonate diol used to form the polycarbonate segments. A polycarbonate diol with the appropriate molecular weight may be purchased or polymerized, or a low-molecular-weight polycarbonate diol may be reacted with a chain extender such as diphenyl carbonate to increase the molecular weight and adjust the molecular weight. As chain extenders, alkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, and dibutyl carbonate, or phosgene can also be used, but diphenyl carbonate is advantageous because it allows for the easiest molar ratio control and has good polymerizability.

In the thermoplastic polyester elastomer (a) used in the present invention, the mass ratio of the hard segment (a-1) to the soft segment (a-2) is generally preferably (a-1):(a-2) = 20:80 to 80:20, more preferably 20:80 to 70:30, and even more preferably 30:70 to 70:30.

The polyester elastomer (a) used in the present invention can be produced by known methods. For example, any of the following methods may be used: a method in which a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight glycol, and a soft segment component are subjected to a transesterification reaction in the presence of a catalyst, followed by polycondensation of the resulting reaction product; a method in which a dicarboxylic acid, an excess amount of a glycol, and a soft segment component are subjected to an esterification reaction in the presence of a catalyst, followed by polycondensation of the resulting reaction product; a method in which a hard segment polyester is prepared in advance, a soft segment component is added to this, and the components are randomized by a transesterification reaction; a method in which the hard and soft segments are linked with a chain linking agent; or, when poly(ε-caprolactone) is used for the soft segment, an addition reaction of ε-caprolactone monomer to the hard segment.

The melting point of the polyester elastomer (a) used in the present invention is preferably 170 to 270°C, more preferably 180 to 250°C, and even more preferably 190 to 230°C. The glass transition temperature of the polyester elastomer (a) is preferably -60 to 40°C, more preferably -55 to 30°C, and even more preferably -45 to 20°C. Furthermore, the reduced viscosity of the polyester elastomer (a) is preferably 0.5 to 1.5 dl/g, more preferably 0.6 to 1.4 dl/g, and even more preferably 0.7 to 1.3 dl/g.

<Acrylic elastomer (b)>
The acrylic elastomer (b) (hereinafter also referred to simply as component (b)) used in the present invention preferably contains a vinyl monomer as a constituent component, and more preferably contains two or more (meth)acrylic monomers and, if necessary, other copolymerizable vinyl monomers as constituent components. The acrylic elastomer (b) is obtained by polymerizing a vinyl monomer to increase its molecular weight through a polymerization reaction.

Examples of (meth)acrylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, phenyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, (meth)acrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and phenoxyethyl (meth)acrylate. In this specification, alkyl group names without subscripts include isomers such as n-, iso-, sec-, and tert-, unless otherwise specified, and (meth)acrylic refers to both methacrylic and acrylic.

The amount of (meth)acrylic monomer is preferably 20% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more, of all the constituent components of the acrylic elastomer (b).

Other copolymerizable vinyl monomers include styrene, α-methylstyrene, vinyl acetate, ethylene, propylene, butadiene, isoprene, and maleic anhydride. Of these, styrene, α-methylstyrene, and ethylene are preferred. These vinyl monomers may be used in combination within a range that does not impair the objectives of the present invention (preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less).

Methods for polymerizing the monomers to obtain the acrylic elastomer (b) include, for example, radical polymerization, living anionic polymerization, and living radical polymerization. Furthermore, examples of the polymerization form include solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization.

Acrylic elastomer (b) is preferably a block copolymer composed of a hard segment (b-1) and a soft segment (b-2), more preferably a block copolymer having two or more blocks constituting a hard segment and one or more blocks constituting a soft segment, and even more preferably a triblock copolymer having two blocks constituting a hard segment on both sides of one block constituting a soft segment (i.e., one block constituting a hard segment on each side of one block constituting a soft segment). The proportion of the triblock copolymer in acrylic elastomer (b) is preferably 60% by mass or more, more preferably 70% by mass or more. In addition to the triblock copolymer, acrylic elastomer (b) may also contain a diblock copolymer and a multiblock copolymer.

In order for the acrylic elastomer (b) to exhibit the properties of a thermoplastic elastomer, it preferably has a hard segment (b-1) with a glass transition temperature above room temperature.

The glass transition temperature of the blocks constituting the hard segment (b-1) is preferably 20 to 200°C, more preferably 30 to 180°C, and even more preferably 50 to 150°C, from the viewpoint of maintaining the toughness of the composition in the normal temperature range. If the glass transition temperature of the blocks constituting the hard segment (b-1) is too low, the resulting composition may lack heat resistance, and it is difficult to obtain raw materials for blocks with glass transition temperatures exceeding 200°C.

The vinyl monomer constituting the hard segment (b-1) is preferably one or more (meth)acrylic monomers. Examples of such (meth)acrylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, phenyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, (meth)acrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and phenoxyethyl (meth)acrylate. Among these, from an economical standpoint, methyl methacrylate, ethyl methacrylate, and butyl methacrylate are preferred, with methyl methacrylate being more preferred.

The vinyl monomer that constitutes the hard segment (b-1) preferably contains the above-mentioned (meth)acrylic monomer, but may also contain other monomers within a range that does not impair the objectives of the present invention (preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less). Furthermore, the hard segment can also be produced by increasing the molecular weight through a polymerization reaction.

Copolymerizable vinyl monomers include, for example, ethylene, propylene, α-olefins, styrene, α-methylstyrene, acrylonitrile, parahydroxystyrene, vinyl alcohol, acrylic acid, methacrylic acid, acrylamide, methacrylamide, methyl vinyl ether, vinyl benzoate, maleic acid, and N-cyclohexylmaleimide, with styrene, α-methylstyrene, and ethylene being preferred.

The glass transition temperature of the block constituting the soft segment (b-2) is preferably -100 to 20°C, more preferably -80 to 10°C, and even more preferably -70 to 0°C. If the glass transition temperature of the block constituting the soft segment (b-2) is too high, the resulting composition may lack flexibility, and it is difficult to obtain raw materials for blocks with glass transition temperatures below -100°C.

The vinyl monomer constituting the soft segment (b-2) is preferably one or more acrylic monomers. Preferred acrylic monomers, due to their high reactivity with transesterification catalysts, include ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, benzyl acrylate, and phenylethyl acrylate.

Furthermore, the acrylic monomer constituting the soft segment (b-2) so that the glass transition temperature of the soft segment (b-2) is 20°C or lower is preferably one or more acrylic monomers. Such an acrylic monomer is preferably at least one selected from the group consisting of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, n-hexyl acrylate, ethylhexyl acrylate, n-heptyl acrylate, n-octyl acrylate, and phenylethyl acrylate. From the viewpoint of being less compatible with the hard segment (b-1) and likely to form a phase-separated structure, at least one selected from the group consisting of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, n-hexyl acrylate, ethylhexyl acrylate, n-heptyl acrylate, and n-octyl acrylate, or a combination thereof, is more preferred. Ethyl acrylate, n-butyl acrylate, ethylhexyl acrylate, or a combination thereof is even more preferred.

The vinyl monomer constituting the soft segment (b-2) preferably contains the above-mentioned acrylic monomer, but may also contain other monomers within a range that does not impair the objectives of the present invention (preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less). In other words, the amount of the above-mentioned acrylic monomer among the vinyl monomers constituting the soft segment (b-2) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

The mass ratio ((b-1)/(b-2)) of the hard segment (b-1) to the soft segment (b-2) is preferably 15/85 to 85/15, more preferably 20/80 to 80/20, and even more preferably 30/70 to 70/30. By keeping the mass ratio of the hard segment (b-1) to the soft segment (b-2) within this range, ATF resistance can be further improved, and long-term reliability at 150°C can also be improved.

Commercially available products that can be used as acrylic elastomer (b) include Kuralyte manufactured by Kuraray Co., Ltd., Nanostrength manufactured by Arkema, and Nabstar manufactured by Kaneka Corporation.

From the viewpoint of mechanical properties such as tensile strength, the weight average molecular weight of the acrylic elastomer (b) is preferably 10,000 or more, more preferably 20,000 or more, even more preferably 30,000 or more, and particularly preferably 40,000 or more. Furthermore, from the viewpoint of ease of handling and maintaining a melt viscosity suitable for producing molded articles as sealing materials, it is preferably 1,000,000 or less, more preferably 800,000 or less, even more preferably 700,000 or less, and particularly preferably 200,000 or less. From these viewpoints, the weight average molecular weight of the acrylic elastomer (b) may be 10,000 to 1,000,000, preferably 20,000 to 1,000,000, more preferably 30,000 to 800,000, even more preferably 40,000 to 700,000, and particularly preferably 40,000 to 200,000.

Furthermore, the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic elastomer (b): Mw/Mn is preferably 1 to 5, more preferably 1.1 to 3, and even more preferably 1.1 to 2.

In the present invention, the acrylic elastomer (b) may be one whose molecular weight is increased by an ester exchange catalyst, a radical polymerization initiator, or the like, to a higher value than the polymerization average molecular weight of the acrylic elastomer (b) (i.e., the vinyl monomer) in the raw material stage. In such cases, the weight average molecular weight distribution will be broad or multimodal (having two or more peaks), but the weight average molecular weight mentioned above is the overall average molecular weight.

The flow initiation temperature of the acrylic elastomer (b) is preferably 80°C or higher from the viewpoint of the heat resistance of the composition, and is preferably 220°C or lower from the viewpoint of the thermoplasticity (fluidity) of the composition. From these viewpoints, the flow initiation temperature of the acrylic elastomer (b) is preferably 80 to 220°C, and more preferably 100 to 200°C.

The amount of acrylic elastomer (b) is preferably 8 to 280 parts by mass per 100 parts by mass of polyester elastomer (a), more preferably 8 to 100 parts by mass, even more preferably 15 to 90 parts by mass, even more preferably 20 to 80 parts by mass, and particularly preferably 30 to 70 parts by mass. By using a specified amount of acrylic elastomer (b) or more, adhesion to each substrate can be improved, and by using a specified amount of acrylic elastomer (b) or less, durability at 150°C can be improved.

<Epoxy resin (c)>
The epoxy resin (c) used in the present invention is not particularly limited as long as it has a glycidyl group, but may be, for example, a glycidyl ether, a glycidyl ester, a glycidyl amine, an alicyclic epoxide, or an aliphatic epoxide. Examples of the glycidyl ether include glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, novolac glycidyl ether, dicyclopentadiene glycidyl ether, and brominated bisphenol A diglycidyl ether; glycidyl ester types such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; glycidyl amines such as dicyclopentadiene, triglycidyl isocyanurate, glycidyl hindan, tetraglycidyldiaminodiphenylmethane, triglycidyl para-aminophenol, triglycidyl meta-aminophenol, diglycidyl aniline, diglycidyl toluidine, tetraglycidyl meta-xylenediamine, diglycidyl tribromoaniline, and tetraglycidyl bisaminomethylcyclohexane; and alicyclic or aliphatic epoxides such as 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. In particular, in order to ensure high adhesion in the encapsulating resin composition, those with good compatibility with the polyester elastomer (a) and acrylic elastomer (b) are more preferred. Of these, bisphenol A diglycidyl ether or dicyclopentadiene glycidyl ether is preferred. The epoxy resin (c) preferably has a number-average molecular weight of 450 to 40,000. If the number-average molecular weight is too low, the encapsulating composition may be prone to softening, resulting in poor mechanical properties. If the number-average molecular weight is too high, the compatibility of the epoxy resin (c) with the polyester elastomer (a) and acrylic elastomer (b) may decrease, potentially impairing adhesion to the substrate.

The amount of epoxy resin (c) is preferably 0.5 to 30 parts by mass, more preferably 1.0 to 25 parts by mass, and even more preferably 2.0 to 20 parts by mass, per 100 parts by mass of polyester elastomer (a). If it is less than 0.5 parts by mass, the effect on adhesion may be poor. Furthermore, if it exceeds 30 parts by mass, bleed-out may occur, resulting in poor appearance.

<Antioxidant (d1)/Light Stabilizer (d2)>
The polyester elastomer composition of the present invention preferably contains an antioxidant (d1) and/or a light stabilizer (d2), more preferably an antioxidant (d1). The inclusion of the antioxidant (d1) and/or a light stabilizer (d2) in the polyester elastomer-containing composition can improve moist heat resistance reliability. The antioxidant (d1) is preferably an antioxidant containing a phenol skeleton, an antioxidant containing a sulfur atom, or an antioxidant containing a phosphorus atom. It is more preferable to include at least one antioxidant containing a phenol skeleton and an antioxidant containing a sulfur atom, and it is even more preferable to include both at least one antioxidant containing a phenol skeleton and at least one antioxidant containing a sulfur atom. The inclusion of both at least one antioxidant containing a phenol skeleton and at least one antioxidant containing a sulfur atom can improve moist heat resistance and also improve long-term reliability at 150°C.

Preferred light stabilizers (d2) are benzotriazole-based light stabilizers, benzophenone-based light stabilizers, hindered amine-based light stabilizers, nickel-based light stabilizers, and benzoate-based light stabilizers.

Preferred examples of antioxidants containing a phenol skeleton include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (e.g., trade name Irganox 1010, manufactured by BASF) and N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide) (e.g., trade name SONGNOX 1098, manufactured by SONGWON), and preferred examples of antioxidants containing sulfur atoms include dilauryl-3,3'-thiodipropionate (e.g., trade name Lasmit LG, manufactured by Daiichi Kogyo Seiyaku).

Among antioxidants containing a phenol skeleton, hindered phenol-based antioxidants are most preferred, such as pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide, benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 side chain alkyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxy)benzene, 1,6- Examples include hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate, 3,3'-thiobispropionic acid dioctadecyl ester, 2,5,7,8-tetramethyl-(4',8',12'-trimethyltridecyl)chroman-6-ol, stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4',4'-butylidenebis(3-methyl-6-tert-butylphenol), and 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5)-undecane.

Examples of antioxidants containing sulfur atoms include 3,3'-thiobispropionic acid didodecyl ester, 4,4'-thiobis(3-methyl-6-tert-butylphenol), dilauryl-3,3'-thiobispropionate, dimyristyl-3,3'-thiobispropionate, distearyl-3,3'-thiobispropionate, pentaerythritol tetrakis(3-laurylthiobispropionate), and dioctadecyl-3,3'-thiobispropionate, but are not limited to these, and any antioxidant containing a sulfur atom can be used as appropriate.

Antioxidants containing phosphorus atoms include tributyl phosphate, tris(2,4-dibutylphenyl) phosphite, distearyl pentaerythritol diphosphite, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl) phosphite, trisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol Examples of antioxidants that contain phosphorus atoms include tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite, and the like. However, they are not limited to these and any antioxidant containing a phosphorus atom can be used as appropriate.

Examples of benzotriazole-based light stabilizers include 2-(3,5-di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, and 2-[2-hydroxy-3,5-di(1,1-dimethylbenzyl)]-2H-benzotriazole. However, without being limited to these, any benzotriazole-based light stabilizer can be used as appropriate.

Examples of benzophenone-based light stabilizers include 2-hydroxy-4-(octyloxy)benzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid, 2-hydroxy-4-n-dodecyloxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2,2'-dihydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, but are not limited to these and any benzophenone-based light stabilizer can be used as appropriate.

Hindered amine light stabilizers include bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, dimethyl succinate/1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene〈2,2,6, 6-tetramethyl-4-piperidyl)imino}], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-s-triazine-2,4,6(1H,3H,5H)trione, tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-2,4,6-[1H,3H,5H]trione, etc., but are not limited to these, and any hindered amine light stabilizer can be used as appropriate.

Nickel-based light stabilizers include [2,2'-thio-bis(4-tert-octylphenolate)]-2-ethylhexylamine-nickel-(II), nickel dibutyldithiocarbamate, and [2,2'-thio-bis(4-tert-octylphenolate)]n-butylamine-nickel, but are not limited to these and any nickel-based light stabilizer can be used as appropriate.

Examples of benzoate-based light stabilizers include 2,4-di-tert-butylphenyl-3,5'-di-tert-butyl-4'-hydroxybenzoate, but are not limited to these, and any benzoate-based light stabilizer can be used as appropriate.

The amount of antioxidant (d1) (total amount when multiple types are used) is preferably 0.5 to 10 parts by mass, more preferably 1 to 9 parts by mass, even more preferably 1.5 to 8 parts by mass, and even more preferably 2 to 7 parts by mass, per 100 parts by mass of polyester elastomer (a). In particular, it is preferable to contain at least one antioxidant containing a phenol skeleton and at least one antioxidant containing a sulfur atom in a total amount within the above range. By setting the amount of antioxidant (d1) within the above range, long-term reliability at 150°C can be improved.
The amount of the light stabilizer (d2) (total amount when a plurality of types are used) is preferably 0.5 to 10 parts by mass per 100 parts by mass of the polyester elastomer (a).

It is effective to add a phosphorus-based compound as a stabilizing aid to the polyester elastomer-containing composition of the present invention. Phosphorus-based compounds suitable as stabilizing aids include phosphonic acids such as phenylphosphonic acid. Specific examples of phosphonic acids include phenylphosphonic acid, as well as benzylphosphonic acid, o-methylbenzylphosphonic acid, naphthylphosphonic acid, chlorophenylphosphonic acid, difluorophenylphosphonic acid, tolylphosphonic acid, ethylphosphonic acid, tert-butylphosphonic acid, cyclohexylphosphonic acid, tetradecylphosphonic acid, methylphosphonic acid, di-tert-butylphenylphosphonic acid, diisopropylphenylphosphonic acid, methoxyphenylphosphonic acid, ethoxyphenylphosphonic acid, tert-butoxyphenylphosphonic acid, isopropoxyphenylphosphonic acid, benzyloxyphenylphosphonic acid, dimethoxyphenylphosphonic acid, phenoxyphenylphosphonic acid, tolyloxyphenylphosphonic acid, methoxyphenoxyphenylphosphonic acid, phenoxyethylphosphonic acid, biphenyloxyethylphosphonic acid, phenoxypropylphosphonic acid, biphenyloxypropylphosphonic acid, benzyloxyethylphosphonic acid, and benzyloxypropylphosphonic acid. The appropriate amount of these phosphorus-based compounds to be added varies depending on factors such as the reaction temperature and catalyst amount, but it is preferable to adjust the amount added so that 60 to 140 parts by mass of phosphorus atoms are contained per 100 parts by mass of metal atoms contained in the catalyst. If the amount of phosphorus-based compound added is too small, transesterification will not be sufficiently suppressed, and the crystallinity of the resulting elastomer will not be improved. On the other hand, if the amount of phosphorus-based compound added is too large, although good crystallinity will be achieved, there is also the risk of damage to the electrical and electronic components being sealed due to bleed-out of the phosphorus-based compound.

There are no particular restrictions on the method of adding the phosphorus-based compound, but adding it after the compatibilization reaction between the soft and hard segments is advantageous because it helps prevent thermal degradation during polyester elastomer production in the early stages of production. However, it may also be added during remelting or compounding with additives.

<Polycarbodiimide resin (e)>
The polyester elastomer composition of the present invention preferably contains a polycarbodiimide resin (e). By containing the polycarbodiimide resin (e), it is possible to improve the moist heat resistance and preferably improve the long-term reliability at 150°C. The amount of the polycarbodiimide resin (e) is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the polyester elastomer (a).

The polyester elastomer-containing composition of the present invention can also contain various additives (other than the polyester elastomer (a), acrylic elastomer (b), epoxy resin (c), antioxidant (d1), light stabilizer (d2), and polycarbodiimide resin (e)). Additives that can be added include resins other than those mentioned above, inorganic fillers, coloring pigments including carbon black, inorganic or organic fillers, coupling agents, tackiness improvers, quenchers, stabilizers such as metal deactivators, and flame retardants. The total amount of these various additives is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of polyester elastomer (a).

The polyester elastomer-containing composition of the present invention is preferably evaluated in the manner described in the Examples below for various properties within the following ranges.
The initial breaking elongation is, for example, 700 to 1500%.
The shear adhesive strength is preferably 1.0 MPa or more, more preferably 2.0 MPa or more, and the upper limit may be, for example, 4.5 MPa in the case of PBT (polybutylene terephthalate) and 8.5 MPa in the case of glass epoxy. In other words, the shear adhesive strength is preferably 1.0 to 4.5 MPa, more preferably 2.0 to 4.5 MPa in the case of PBT, and preferably 1.0 to 8.5 MPa, more preferably 2.0 to 8.5 MPa in the case of glass epoxy.
The rate of change in tensile elongation in a long-term reliability evaluation at 85°C and 85% humidity is preferably less than 50%, more preferably less than 30%, and even more preferably less than 20%, and the lower limit may be, for example, 3% (i.e., 3% or more and less than 50% is preferred, 3% or more and less than 30% is more preferred, and 3% or more and less than 20% is even more preferred).
The rate of change in tensile elongation in a long-term reliability evaluation at 150°C is preferably less than 50%, more preferably less than 30%, and even more preferably less than 20%, and the lower limit may be, for example, 5% (i.e., 5% or more and less than 50% is preferred, 5% or more and less than 30% is more preferred, and 5% or more and less than 20% is even more preferred).
The rate of change in tensile elongation in the ATF resistance evaluation is preferably less than 50%, more preferably less than 30%, and even more preferably less than 20%, with the lower limit being preferably 0% (i.e., 0% or more and less than 50% is preferred, 0% or more and less than 30% is more preferred, and 0% or more and less than 20% is even more preferred).

<Sealed Electrical and Electronic Component>
The polyelastomer-containing composition of the present invention can be molded and suitably used as a sealant for electrical and electronic components. To obtain the sealed electrical and electronic component of the present invention, for example, an electrical and electronic component is placed in a mold, and then the polyester elastomer-containing composition of the present invention is heated and melted at approximately 120 to 270°C using a screw-type hot-melt molding applicator and injected into the mold through a nozzle. After a certain cooling period, the molded product is removed from the mold, yielding a sealed electrical and electronic component in which the electrical and electronic component is sealed with the molded sealant. The temperature and pressure during injection of the molded sealant are preferably 200°C to 260°C and 0.1 MPa to 40 MPa. By performing sealing under these conditions, a sealed component can be obtained without damaging the electrical and electronic component and without breakage or misalignment. Furthermore, a sealed electrical and electronic component with a good shape and free of short shots, burrs, and sink marks can be easily obtained.

As molding and processing machines for obtaining the sealed electrical and electronic components of the present invention, in addition to ordinary injection molding machines, extrusion molding machines, plunger-type molding machines, and hot melt molding applicators can be used.

This application claims the benefit of priority based on Japanese Patent Application No. 2024-049858, filed March 26, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-049858, filed March 26, 2024, are incorporated herein by reference.

The present invention will be explained in more detail below using examples. However, the present invention is not limited to these examples. In the examples and comparative examples, parts simply refer to parts by mass.

(Physical property evaluation method)

(Melting point)
The melting point was measured using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc. 5 mg of the measurement sample was placed in an aluminum pan, the pan was sealed with a lid, and the pan was held at 250°C for 5 minutes, then rapidly cooled with liquid nitrogen. The sample was then heated from -100°C to 250°C at a heating rate of 20°C/min. The endothermic peak of the obtained curve was taken as the melting point.

(glass transition temperature)
The glass transition temperature was measured using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc. by placing 5 mg of a measurement sample in an aluminum pan, sealing it with a lid, holding it at 250°C for 5 minutes, then quenching it with liquid nitrogen, and then heating it from -100°C to 250°C at a heating rate of 20°C/min. The inflection point of the obtained curve was taken as the glass transition temperature.

(reduced viscosity)
The reduced viscosity was measured at 30° C. using an Ubbelohde viscometer by dissolving 0.05 g of a sample in 25 mL of a mixed solvent (phenol/tetrachloroethane=60/40 (mass ratio)).

(1) Initial Tensile Elongation A plate molding mold (mold inner surface dimensions: width 100 mm x length 100 mm x thickness 2 mm) was prepared, and a vertical injection molding machine (TH40E, manufactured by Nissei Plastics Co., Ltd.) was used to inject the polyester elastomer-containing composition through a gate located at the center of the 100 mm x 100 mm surface to perform molding. The molding conditions were a pressure of 3.0 MPa, a cylinder temperature (Tm + 30°C), and a mold temperature of 30°C. From this 100 mm x 100 mm x 2 mm thick plate, a No. 3 dumbbell (thickness 2 mm) as specified in JIS K6251:2010 was cut using a punching machine. The tensile elongation of the No. 3 dumbbell was measured in accordance with JIS K6251:2010.

(2) PBT and FR4 Shear Adhesion Strength Shear adhesion strength test specimens were prepared by cutting the substrate into 70 mm x 25 mm and 40 mm x 25 mm sizes and wiping the surface with acetone to remove oil. The substrates were then fixed inside a shear adhesion test mold, overlapping each other by 10 mm so that the glass epoxy or PBT surface of the substrate would contact the molten polyester elastomer-containing composition (encapsulating composition), with a width of 25 mm and a thickness of 1 mm for the encapsulating resin composition to be molded. Next, using a vertical injection molding machine (THX, manufactured by Nissei Plastics Co., Ltd.), the encapsulating composition with a moisture content of 0.1% or less was injected and molded. The molding conditions were a pressure of 3.0 MPa, a cylinder temperature (Tm + 30°C), and a mold temperature of 30°C. The molded product was then removed from the mold, and a shear adhesion strength test specimen (substrate/encapsulating resin composition layer/substrate) was obtained, in which the molded resin composition was sandwiched between the substrates. The shear adhesion test pieces were stored for one day in an atmosphere of 23°C and 50% relative humidity. Then, using an autograph (AG-IS manufactured by Shimadzu Corporation), each substrate was clamped with a chuck and the resin composition was peeled off in the shear direction to measure the initial shear adhesion strength. The pulling speed was 50 mm/min. The following two types of substrates (adherends) were evaluated:
Resist-free glass epoxy (GE) substrate: Nikkan Kogyo FR4
PBT substrate: Polybutylene terephthalate (GF 30%), manufactured by Polyplastics Co., Ltd.: Duranex 3300
<Adhesive strength evaluation criteria>
○: 2.0 MPa or more.
Δ: 1.0 MPa or more and less than 2.0 MPa.
×: Less than 1.0.

(3) Long-Term Reliability at 85°C and 85% Humidity A plate molding mold (mold inner surface dimensions: 100 mm wide x 100 mm long x 2 mm thick) was prepared, and a vertical injection molding machine (TH40E, manufactured by Nissei Plastics Co., Ltd.) was used to inject the polyester elastomer resin composition through a gate located at the center of the 100 mm x 100 mm surface. Molding conditions were a pressure of 3.0 MPa, a cylinder temperature (Tm + 30°C), and a mold temperature of 30°C. From this 100 mm x 100 mm x 2 mm thick plate, a No. 3 dumbbell (2 mm thick) as specified in JIS K6251:2010 was cut using a punching machine. The No. 3 dumbbell was subjected to 1,000 hours of processing in a thermo-hygrostat set at 85°C and 85% humidity, and then allowed to stand overnight at room temperature and humidity, after which the tensile elongation was measured. The rate of change in tensile elongation relative to the initial tensile elongation was calculated and expressed according to the following criteria, and used as an index of long-term reliability at 85°C and 85% humidity.
<Evaluation criteria>
A: The rate of change is less than 20%.
◯: The rate of change is 20% or more and less than 30%.
Δ: The rate of change is 30% or more and less than 50%.
×: The rate of change is 50% or more.

(4) Long-Term Reliability at 150°C A plate molding mold (mold inner surface dimensions: 100 mm wide x 100 mm long x 2 mm thick) was prepared, and a vertical injection molding machine (TH40E, manufactured by Nissei Plastics Co., Ltd.) was used to inject the polyester elastomer resin composition through a gate located at the center of the 100 mm x 100 mm surface. Molding conditions were a pressure of 3.0 MPa, a cylinder temperature (Tm + 30°C), and a mold temperature of 30°C. From this 100 mm x 100 mm x 2 mm thick plate, a No. 3 dumbbell (2 mm thick) as specified in JIS K6251:2010 was cut using a punching machine. The No. 3 dumbbell was processed for 1,000 hours in a gear oven set at 150°C, then allowed to stand overnight at room temperature and humidity, after which the tensile elongation was measured. The retention rate of tensile elongation relative to the initial tensile elongation was calculated and expressed according to the following criteria, which was used as an index of long-term reliability at 150°C.
<Evaluation criteria>
A: The rate of change is less than 20%.
◯: The rate of change is 20% or more and less than 30%.
Δ: The rate of change is 30% or more and less than 50%.
×: The rate of change is 50% or more.

(5) ATF Resistance A plate molding mold (mold inner surface dimensions: width 100 mm x length 100 mm x thickness 2 mm) was prepared, and a vertical injection molding machine (TH40E, manufactured by Nissei Plastics Co., Ltd.) was used to inject the polyester elastomer-containing composition through a gate located at the center of the 100 mm x 100 mm surface to mold the plate. Molding conditions were a pressure of 3.0 MPa, a cylinder temperature (Tm + 30°C), and a mold temperature of 30°C. From this 100 mm x 100 mm x 2 mm thick plate, a No. 3 dumbbell (2 mm thick) as specified in JIS K6251:2010 was cut using a punching machine. ATF (manufactured by Toyota) was placed in a sealed metal container and heated to 50°C. The No. 3 dumbbell was immersed in the ATF (manufactured by Toyota) for one week, after which the ATF was wiped off and the plate was left standing at room temperature and humidity for one day and night, after which the tensile elongation was measured. The retention rate of tensile elongation relative to the initial tensile elongation was calculated and expressed according to the following criteria, which was used as an index of ATF resistance.
<Evaluation criteria>
A: The rate of change is less than 20%.
◯: The rate of change is 20% or more and less than 30%.
Δ: The rate of change is 30% or more and less than 50%.
×: The rate of change is 50% or more.

(Production Example of Aliphatic Polycarbonate Diol)
100 parts by mass of poly(hexamethylene carbonate) diol (number average molecular weight 2000) and 9.6 parts by mass of diphenyl carbonate were charged into a reaction vessel and reacted at a temperature of 205°C and 130 Pa. After 2 hours, the contents were cooled and the produced polymer was removed to obtain aliphatic polycarbonate diol A. The aliphatic polycarbonate diol A had a number average molecular weight of 13000, a melting point of 40°C, a glass transition temperature of -55°C, and a reduced viscosity of 0.68 dl/g.

(Production Example of Polyester Elastomer A)
A reactor equipped with a stirrer, thermometer, and distillation condenser was charged with 529 parts by mass of dimethyl terephthalate, 491 parts by mass of 1,4-butanediol, and 0.28 parts by mass of tetrabutyl titanate as a catalyst, and a transesterification reaction was carried out at 170 to 220°C for 2 hours. After completion of the transesterification reaction, the temperature was raised to 255°C, while the pressure in the system was slowly reduced to 665 Pa at 255°C over 60 minutes. A polycondensation reaction was then carried out for 30 minutes at 133 Pa or less to obtain polybutylene terephthalate. Next, 100 parts by mass of polybutylene terephthalate (PBT), the hard segment component, and 75 parts by mass of aliphatic polycarbonate diol A, the soft segment component, were stirred at 230 to 245°C and 130 Pa for 1 hour, and it was confirmed that the resin had become transparent. The contents were then removed and cooled to obtain polyester elastomer A.

(Production Example of Polyester Elastomer B)
A reactor equipped with a stirrer, thermometer, and distillation condenser was charged with 529 parts by mass of dimethyl terephthalate, 491 parts by mass of 1,4-butanediol, and 0.28 parts by mass of tetrabutyl titanate as a catalyst, and a transesterification reaction was carried out at 170 to 220°C for 2 hours. After completion of the transesterification reaction, the temperature was raised to 255°C, while the pressure in the system was slowly reduced to 665 Pa at 255°C over 60 minutes. A polycondensation reaction was then carried out for 30 minutes at 133 Pa or less to obtain polybutylene terephthalate. Next, 100 parts by mass of polybutylene terephthalate PBT, the hard segment component, and 43 parts by mass of aliphatic polycarbonate diol A, the soft segment component, were stirred at 230 to 245°C and 130 Pa for 1 hour, and it was confirmed that the resin had become transparent. The contents were then removed and cooled to obtain polyester resin B.

(Production Example of Polyester Elastomer C)
A reactor equipped with a stirrer, thermometer, and distillation condenser was charged with 529 parts by mass of dimethyl terephthalate, 491 parts by mass of 1,4-butanediol, and 0.28 parts by mass of tetrabutyl titanate as a catalyst, and a transesterification reaction was carried out at 170 to 220°C for 2 hours. After completion of the transesterification reaction, the temperature was raised to 255°C, while the pressure in the system was slowly reduced to 665 Pa at 255°C over 60 minutes. A polycondensation reaction was then carried out for 30 minutes at 133 Pa or less to obtain polybutylene terephthalate. Next, 100 parts by mass of polybutylene terephthalate PBT, the hard segment component, and 150 parts by mass of aliphatic polycarbonate diol A, the soft segment component, were stirred at 230 to 245°C and 130 Pa for 1 hour, and it was confirmed that the resin had become transparent. The contents were then removed and cooled to obtain polyester resin C.

(Production Example of Polyester Elastomer D)
A reactor equipped with a stirrer, thermometer, and distillation condenser was charged with 250.1 parts by mass of dimethyl terephthalate, 169.4 parts by mass of 1,4-butanediol, and 0.13 parts by mass of tetrabutyl titanate as a catalyst, and the transesterification reaction was carried out at 170 to 220 ° C. for 2 hours. After the transesterification reaction was completed, 695.4 parts by mass of polytetramethylene glycol "PTMG1000" (manufactured by Mitsubishi Chemical) having a number average molecular weight of 1000 and 2.0 parts by mass of Irganox 1330 were added, and the temperature was raised to 255 ° C., while the pressure in the system was slowly reduced to 665 Pa at 255 ° C. over 60 minutes. Then, a polycondensation reaction was carried out at 133 Pa or less for 60 minutes, and polyester resin D was obtained.

Details of the abbreviations for the ingredients shown in Table 1 are as follows:

PBT: Polybutylene terephthalate, number average molecular weight 20,000
Aliphatic PCD: Aliphatic polycarbonate diol PTMG1000: Polytetramethylene glycol, number average molecular weight 1,000

Example 1
100 parts by mass of polyester elastomer A, 30 parts by mass of acrylic elastomer A, 4 parts by mass of epoxy resin A, 1.1 parts by mass of antioxidant A, 1.1 parts by mass of antioxidant B, and 0.7 parts by mass of carbodiimide resin A were uniformly mixed, and then melt-kneaded using a twin-screw extruder at a die temperature of 250°C to obtain composition 1. The blending composition and evaluation results of composition 1 are shown in Table 2.

(Examples 2 to 16, Comparative Examples 1 to 4)
Compositions 2 to 16 for sealing electrical and electronic components and comparative compositions 1 to 4 were prepared in the same manner as in Example 1, except that the formulation was changed as shown in Table 2, and then evaluated. The evaluation results are shown in Table 2.

The acrylic elastomer (b), epoxy resin (c), antioxidant (d1), polycarbodiimide (e), and polyolefin (f) used in Table 2 are as follows:

(Acrylic elastomer (b))
A: Kurariti KL-LH8156 (Kuraray Co., Ltd.), Mw 100,000, Mw/Mn 1.2, flow temperature 160°C: PMMA-b-MA/nBA-b-PMMA triblock copolymer, hard segment/soft segment ratio = 30/70 (mass ratio), hard block Tg: 100 to 120°C, soft block Tg: -30 to -40°C
B: Kuraty LA2140 (Kuraray Co., Ltd.), Mw 80,000, Mw/Mn 1.2, flow initiation temperature 150°C, PMMA-b-nBA-b-PMMA triblock copolymer, hard segment/soft segment ratio = 20/80 (mass ratio), hard block Tg: 100 to 120°C, soft block Tg: -40 to -50°C
C: Clarity LA2270 (Kuraray Co., Ltd.), Mw 70,000, Mw/Mn 1.3, flow initiation temperature 175°C, PMMA-b-nBA-b-PMMA triblock copolymer, hard segment/soft segment ratio = 40/60 (mass ratio), hard block Tg: 100 to 120°C, soft block Tg: -40 to -50°C
In the above acrylic elastomers (b) A to C, PMMA represents polymethyl methacrylate, MA represents methacrylic acid, and nBA represents normal butyl acrylate.

(Epoxy resin (c))
A: JER-1007K (manufactured by Mitsubishi Chemical Corporation, bisphenol A glycidyl ether, Mn 2900)
B: HP-7200H (DIC Corporation), dicyclopentadiene glycidyl ether, Mn 550

(Antioxidant (d1))
A: Irganox 1010 (manufactured by BASF), a hindered phenol-based antioxidant B: Lasmit LG (manufactured by Daiichi Kogyo Seiyaku), a sulfur atom-containing antioxidant C: SONGNOX 1098 (manufactured by SONGWON), a hindered phenol-based antioxidant

(Polycarbodiimide (e))
A: Carbodiimide resin: HMV-15CA (manufactured by Nisshinbo Chemical Inc.)

(Polyolefin (f))
A: Polyolefin: Excellen VL EUL731 (manufactured by Sumitomo Chemical Co., Ltd.)

As is clear from Table 2, Examples 1 to 16 have ATF resistance, durability in moist and heat environments, and high adhesion to various substrates, and Examples 1 to 15 also have good durability at 150°C. In contrast, Comparative Example 1 does not contain acrylic elastomer (b), so adhesion to PBT and glass epoxy is poor. Comparative Example 2 does not contain epoxy resin (c), so adhesion to PBT is poor. Comparative Example 3 has poor ATF resistance and durability at 150°C because the soft segment (a-2) of the polyester elastomer (a) is made of aliphatic polyether. Comparative Example 4 has poor ATF resistance because polyolefin was used instead of acrylic elastomer (b).

The polyester elastomer-containing composition of the present invention exhibits minimal change after immersion in ATF, meaning it has excellent ATF resistance, and also exhibits excellent durability and excellent adhesion to various substrates without deterioration in mechanical properties even in humid and hot environments. These properties make it useful for sealing electrical and electronic components.

Claims (15)

A polyester elastomer (a) having a hard segment (a-1) containing a crystalline aromatic polyester and a soft segment (a-2) containing an aliphatic polycarbonate;
A polyester elastomer-containing composition comprising an acrylic elastomer (b) and an epoxy resin (c). The polyester elastomer-containing composition according to claim 1, further comprising an antioxidant (d1) and/or a light stabilizer (d2). The polyester elastomer-containing composition according to claim 1, wherein the mass ratio of the hard segment (a-1) to the soft segment (a-2): (a-1)/(a-2) is 80/20 to 20/80. The polyester elastomer-containing composition according to claim 1, wherein the acrylic elastomer (b) is present in an amount of 8 to 280 parts by mass per 100 parts by mass of the polyester elastomer (a). The polyester elastomer-containing composition according to claim 1, wherein the epoxy resin (c) is 0.5 to 30 parts by mass per 100 parts by mass of the polyester elastomer (a). The polyester elastomer-containing composition according to claim 1, wherein the carboxylic acid constituting the polyester of the hard segment (a-1) contains terephthalic acid and/or naphthalenedicarboxylic acid, and the total amount of terephthalic acid and naphthalenedicarboxylic acid is 70 mol % or more out of 100 mol % of all carboxylic acids constituting the polyester of the hard segment (a-1). The polyester elastomer-containing composition according to claim 1, wherein the glycol component constituting the polyester of the hard segment (a-1) comprises an alkylene glycol having 2 to 8 carbon atoms and no side chain, and the amount of the alkylene glycol having 2 to 8 carbon atoms and no side chain is 90 mol % or more out of 100 mol % of all glycol components constituting the polyester of the hard segment (a-1). The polyester elastomer-containing composition according to claim 1, wherein the components constituting the polyester of the hard segment (a-1) include butylene terephthalate units and/or butylene naphthalate units, and the total amount of butylene terephthalate units and butylene naphthalate units is 90% by mass or more out of 100% by mass of all components constituting the polyester of the hard segment (a-1). The polyester elastomer-containing composition according to claim 1, wherein the soft segment (a-2) is an aliphatic polycarbonate diol having aliphatic diol residues, and the amount of aliphatic diol residues having 2 to 12 carbon atoms in 100% by mass of the aliphatic diol residues is 90% by mass or more. The acrylic elastomer (b) contains a triblock copolymer constituted by a hard segment (b-1) and a soft segment (b-2), and has one block constituting the hard segment (b-1) on each side of one block constituting the soft segment (b-2),
The polyester elastomer-containing composition according to claim 1, wherein the triblock copolymer accounts for 60% by mass or more of 100% by mass of the acrylic elastomer (b). The polyester elastomer-containing composition according to claim 10, wherein the mass ratio ((b-1)/(b-2)) of the hard segment (b-1) to the soft segment (b-2) is 15/85 to 85/15. The polyester elastomer-containing composition according to claim 10, wherein the vinyl monomer constituting the hard segment (b-1) is at least one selected from the group consisting of methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the monomer constituting the soft segment (b-2) contains 70% by mass or more of at least one selected from the group consisting of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, n-hexyl acrylate, ethylhexyl acrylate, n-heptyl acrylate, and n-octyl acrylate. The polyester elastomer-containing composition according to claim 2, wherein the polyester elastomer-containing composition contains 0.5 to 10 parts by mass of the antioxidant (d) per 100 parts by mass of the polyester elastomer (a). Further, it contains a polycarbodiimide resin (e),
2. The polyester elastomer-containing composition according to claim 1, wherein the amount of the polycarbodiimide resin (e) is 0.1 to 5 parts by mass per 100 parts by mass of the polyester elastomer (a). A sealed electrical/electronic component sealed with the polyester elastomer-containing composition described in any one of claims 1 to 14.