JP2013129786A - Resin composition, resin molded product and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin molded product having low water absorbability, a resin composition giving the resin molded product, and a cable using the resin molded product.SOLUTION: The resin molded product includes (A) an epoxy resin represented by formula (I) or the like and (B) a curing agent represented by formula (III) or the like, wherein (C) one or more of R-Ror one or more of R-Rare a branched-chain alkyl group. The cable has an insulating layer covering a conducting body and the insulating layer comprises the resin molded product. In formula (I), R-Rare independently a branched-chain alkyl group, a hydrogen atom, a divalent linking group, or an epoxy group bonded via a single bond; n-nare each independently an integer of 0-3; the number of the epoxy group in the formula is 1-3; and a part or all of the hydrogen atoms forming the branched-chain alkyl group may be replaced by fluorine atoms. In formula (III), R-Rare each independently a nucleophilic group, a branched-chain alkyl group or a hydrogen atom; n-nare each independently an integer of 0-3; the number of the nucleophilic groups in the formula is 1-3; the number of the branched-chain alkyl groups in the formula is one or more; and a part or all of the hydrogen atoms forming the branched-chain alkyl group may be replaced by fluorine atoms.

Description

  The present invention relates to a resin composition, a resin molded product, and a cable. More specifically, the present invention relates to a composition containing an epoxy resin made of a prepolymer having an epoxy group, a resin molded product obtained by crosslinking and molding the composition, and a cable having an insulating layer made of the resin molded product.

As an insulative material indispensable for power cables, electronic parts, etc., an epoxy resin excellent in water resistance, chemical resistance, dimensional stability and electrical insulation has been conventionally used. Generally, an epoxy resin means both a resin (prepolymer) having an epoxy group, or a curable resin obtained by polymerizing an epoxy group-containing compound or prepolymer with an epoxy group. In the latter case, those in which the prepolymers are cross-linked with each other are sometimes called cross-linked epoxy resins.
As an epoxy resin synthesized by heating and curing a composition containing a compound having an epoxy group before polymerization and a curing agent, for example, an epoxy compound having a biphenyl skeleton is heated and cured with triphenylphosphine as a curing agent. A conventional epoxy resin is known (Patent Document 1).

JP 2011-89133 A

  However, the conventional epoxy resin has a problem in that moisture in the use environment is absorbed by the resin and deteriorates. In an epoxy resin that has deteriorated due to water absorption, the insulation resistance is lowered, and partial discharge is likely to occur. In power cables, electronic parts, and the like in which such an epoxy resin is used as an insulating material, there is a risk of functional failure. In addition, in a crosslinked epoxy resin in which prepolymers having an epoxy group as a side chain are cross-linked via the epoxy group, the absorbed water forms a water tree in the resin, thereby causing partial discharge and insulating resistance. There was a risk of decline.

  The present invention has been made in view of the above circumstances, and provides a resin molded product having a lower water absorption than before, a resin composition forming the resin molded product, and a cable manufactured using the resin molded product. Is an issue.

The resin composition according to claim 1 of the present invention comprises (A) an epoxy resin represented by general formula (I) or general formula (II), and (B) general formula (III) or general formula (IV). And (C) any one or more of R _{1 to} R ₇ or any one or more of R _{11 to} R ₁₈ is a branched alkyl group. To do.

［式中、Ｒ_１〜Ｒ_７はそれぞれ独立して、分岐鎖状のアルキル基、水素原子又は２価の連結基若しくは単結合を介して結合するエポキシ基を表し；ｎ_１〜ｎ_３はそれぞれ独立して０〜３の整数であり；式中の前記エポキシ基の数は１〜３つである。前記分岐鎖状のアルキル基を構成する水素原子の一部又は全部はフッ素原子に置換されていてもよい。］

[Wherein, R _{1 to} R ₇ each independently represents a branched alkyl group, a hydrogen atom, a divalent linking group or an epoxy group bonded via a single bond; n _{1 to} n ₃ each represents It is an integer of 0-3 independently; The number of the said epoxy group in a formula is 1-3. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]

[Wherein, R _{11 to} R ₁₈ each independently represents a branched alkyl group, a hydrogen atom, a divalent linking group or an epoxy group bonded via a single bond; n _{11 to} n ₁₃ and n ₁₈ is each independently an integer of 0 to 3; the number of the epoxy groups in the formula is 1 to 3. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]

［式中、Ｒ_２１〜Ｒ_２７はそれぞれ独立して、求核性基、分岐鎖状のアルキル基又は水素原子を表し；ｎ_２１〜ｎ_２３はそれぞれ独立して０〜３の整数であり；式中の前記求核性基の数は１〜３つであり；式中の前記分岐鎖状のアルキル基の数は１つ以上である。前記分岐鎖状のアルキル基を構成する水素原子の一部又は全部はフッ素原子に置換されていてもよい。］

[Wherein, R _{21 to} R ₂₇ each independently represent a nucleophilic group, a branched alkyl group or a hydrogen atom; n _{21 to} n ₂₃ each independently represents an integer of 0 to 3; The number of the nucleophilic groups in the formula is 1 to 3; the number of the branched alkyl groups in the formula is one or more. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]

［式中、Ｒ_３１〜Ｒ_３８はそれぞれ独立して、求核性基、分岐鎖状のアルキル基又は水素原子を表し；ｎ_３１〜ｎ_３３及びｎ_３８はそれぞれ独立して０〜３の整数であり；式中の前記求核性基の数は１〜３つであり；式中の前記分岐鎖状のアルキル基の数は１つ以上である。前記分岐鎖状のアルキル基を構成する水素原子の一部又は全部はフッ素原子に置換されていてもよい。］

[Wherein, R _{31 to} R ₃₈ each independently represents a nucleophilic group, a branched alkyl group or a hydrogen atom; n _{31 to} n ₃₃ and n ₃₈ each independently represent an integer of 0 to 3; The number of the nucleophilic groups in the formula is 1 to 3; the number of the branched alkyl groups in the formula is one or more. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]

  The epoxy resin has at least one branched alkyl group. For this reason, the hydrophobicity of the epoxy resin is enhanced, and the voids between the resin skeletons that can be formed in the crosslinked epoxy resin obtained by crosslinking (curing) the epoxy resin are formed in the branched alkyl group. Therefore, water molecules are prevented from entering the void (free volume). As a result, the water absorption of the resin molded product (crosslinked epoxy resin) obtained by crosslinking the resin composition according to the present invention can be reduced.

The resin composition according to claim 2 of the present invention is characterized in that, in claim 1, the branched alkyl group is a t-butyl group.
According to this configuration, the hydrophobicity and epoxy equivalent of the epoxy resin can be increased without excessively increasing the rigidity of the epoxy resin. As a result, the water absorption of the crosslinked epoxy resin obtained by crosslinking the epoxy resin can be reduced, and the toughness of the crosslinked epoxy resin can be maintained or improved.
The resin composition according to claim 3 of the present invention is characterized in that, in claim 1 or 2, the number of the epoxy groups in the general formula (I) and the general formula (II) is one.
According to this structure, it has one epoxy group required for bridge | crosslinking, and can increase the hydrophobicity and epoxy equivalent of an epoxy resin more.
The resin molded product according to claim 4 of the present invention is obtained by crosslinking and molding the resin composition according to any one of claims 1 to 3.
The cable according to claim 5 of the present invention includes a conductor and an insulating layer covering the conductor,
The said insulating layer consists of the resin molding of Claim 4. It is characterized by the above-mentioned.
Since the insulating layer made of the resin molding (the crosslinked epoxy resin) has a lower water absorption than before, partial discharge and a decrease in insulation resistance are prevented. For this reason, the cable according to the present invention is excellent in durability, and is unlikely to cause water absorption deterioration even in a hot and humid region.

  The resin molded product of the present invention has a lower water absorption than before, and is less susceptible to deterioration due to water absorption. That is, according to the resin composition of the present invention, a resin molded product with improved water resistance can be provided. Moreover, the cable which uses the resin molding of this invention as an insulating material is excellent in durability.

Hereinafter, although embodiment of this invention is described, this invention is not limited to this embodiment.
<< Resin composition >>
The resin composition according to the present invention includes (A) an epoxy resin represented by the following general formula (I) or general formula (II) (hereinafter sometimes referred to as “prepolymer”).
In addition, the prepolymer demonstrated concretely below may be used individually by 1 type, and may use 2 or more types together.

<Epoxy resin represented by general formula (I)>

In general formula (I), R _{1 to} R ₇ each independently represents a branched alkyl group, a hydrogen atom, a divalent linking group or an epoxy group bonded via a single bond; n _{1 to} n ₃ is each independently an integer of 0 to 3; the number of the epoxy groups in the formula is 1 to 3; and the number of the branched alkyl groups in the formula is one or more.
The branched alkyl group preferably has 3 to 8 carbon atoms. Further, some or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. By using a branched alkyl group substituted with a fluorine atom, the water absorption of the resin molded product according to the present invention can be sometimes lowered.

  Both ends of the epoxy resin represented by the general formula (I) are groups derived from monomers used in the synthesis of the epoxy resin, and are usually hydrogen atoms. However, the hydrogen atoms at both ends may be substituted with other substituents of the type that do not impair the effects of the present invention (for example, the branched alkyl group).

R _{1 to} R ₇ are preferably the epoxy group or the branched alkyl group.
N _{1 to} n ₃ are preferably an integer of 1 to 3, and more preferably an integer of 1 or 2.

The linking group is not particularly limited as long as it is a divalent linking group. For example, an alkylene group having 1 to 3 carbon atoms, a group in which one methylene group constituting the alkylene group is substituted with an oxygen atom or a nitrogen atom. , “—O—”, “—N—” and the like. Among these, “—O—CH ₂ —” which is easily available and can easily introduce an epoxy group into R _{1 to} R ₇ is preferable.

The site to which the epoxy group is bonded via the divalent linking group or the single bond may be any of R _{1 to} R ₇ . In the case of introducing the epoxy groups by Friedel-Crafts reaction using epichlorohydrin, which receives easily attacked R _1, R _2, the epoxy groups to the site of R ₃ is introduced easily.

In this specification, the epoxy equivalent means the mass (g / eq) of a prepolymer having 1 equivalent of an epoxy group, for example, {molecular weight of epoxy resin represented by general formula (I) or general formula (II)} / {Number of epoxy groups of general formula (I) or general formula (II)}. The epoxy group is a polar group and is a hydrophilic group in order to leave a hydroxyl group even after crosslinking (because the crosslinking point has a high polarity). For this reason, it can be said that it is an epoxy resin with high hydrophobicity, so that an epoxy equivalent is large. Therefore, the epoxy resin of this invention is so preferable that an epoxy equivalent is high.
In addition, the said molecular weight at the time of calculating an epoxy equivalent is a formula weight calculated from a chemical formula.

  The number of the epoxy groups in the general formula (I) is preferably 1 to 3, more preferably 1 or 2, and most preferably 1. When the number of the epoxy groups is one, the epoxy equivalent can be increased most.

In general formula (I), at least one branched alkyl group is present, and the bonding site may be any of R _{1 to} R ₇ . In order to reduce the water absorption of the resin molded product (crosslinked epoxy resin) according to the present invention, it is effective to increase the bulk of the epoxy resin. From this point of view, the site to which the branched alkyl group is bonded is preferably R ₁ , R ₂ or R ₃ bonded to the aromatic ring. When these sites are the branched alkyl groups, the bulk of the epoxy resin can be further increased, and the water absorption of the crosslinked epoxy resin obtained after curing can be further reduced. When the branched alkyl group is introduced by a Friedel-Crafts reaction using an alkyl halide, the branched alkyl group is present at the sites of R ₁ , R ₂ , and R ₃ that are easily attacked. Easy to be introduced.

The number of the branched alkyl groups in the general formula (I) is preferably 2 to 6, more preferably 3 to 6, still more preferably 4 to 6, and particularly preferably 5 or 6.
The larger the number of branched alkyl groups, the higher the hydrophobicity and epoxy equivalent of the epoxy resin, and the higher the bulk of the epoxy resin is preferable.

The branched alkyl group is not particularly limited as long as it has 3 to 8 carbon atoms, and is preferably an isopropyl group, a t-butyl group, or an amyl group, and more preferably a t-butyl group. is there. In addition, some or all of the hydrogen atoms bonded to the branched alkyl group may be substituted with fluorine.
Since these branched alkyl groups are bulky, the hydrophobicity and epoxy equivalent of the epoxy resin can be increased, and appropriate rigidity can be imparted to improve toughness. Further, in the crosslinked epoxy resin obtained by curing these epoxy resins having branched chain alkyl groups, the bulky alkyl group fills the void at the molecular level that can be formed between the main chains of the crosslinked polymer. Thus, it is possible to prevent water molecules from entering the resin. As a result, the water absorption of the crosslinked epoxy resin can be further reduced.

The molecular weight of the epoxy resin represented by the general formula (I) is not particularly limited, but is preferably 300 to 6000, and more preferably 600 to 4500.
If it is below the lower limit of the above range, water resistance may not be exhibited. Moreover, when it is more than the upper limit of the said range, rigidity will increase too much, toughness may fall and impact resistance may deteriorate.
The molecular weight is a mass average molecular weight (Mw) converted based on polystyrene in GPC.

  As a suitable thing of the epoxy resin represented by general formula (I), the epoxy resin represented by following Chemical formula (1) can be illustrated, for example. Note that both ends of the epoxy resin represented by the chemical formula (1) are hydrogen atoms.

<Epoxy resin represented by general formula (II)>

In the general formula (II), R _{11 to} R ₁₈ each independently represents a branched alkyl group, a hydrogen atom, a divalent linking group, or an epoxy group bonded via a single bond; n _{11 to} n ₁₃ and n ₁₈ are each independently an integer of 0 to 3; the number of the epoxy groups in the formula is 1 to 3; and the number of the branched alkyl groups in the formula is 1 or more. is there.
The branched alkyl group preferably has 3 to 8 carbon atoms. Further, some or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. By using a branched alkyl group substituted with a fluorine atom, the water absorption of the resin molded product according to the present invention can be sometimes lowered.

  Both ends of the epoxy resin represented by the general formula (II) are groups derived from the monomer used in the synthesis of the epoxy resin, and are usually hydrogen atoms. However, the hydrogen atoms at both ends may be substituted with other substituents of the type that do not impair the effects of the present invention (for example, the branched alkyl group).

R _{11 to} R ₁₈ are preferably the epoxy group or the branched alkyl group.
N _{11 to} n ₁₃ and n ₁₈ are preferably integers of 1 to 3, and are preferably integers of 1 or 2.

The linking group is not particularly limited as long as it is a divalent linking group. For example, an alkylene group having 1 to 3 carbon atoms, a group in which one methylene group constituting the alkylene group is substituted with an oxygen atom or a nitrogen atom. , “—O—”, “—N—” and the like. Among these, “—O—CH ₂ —” which is easily available and can easily introduce an epoxy group into R _{11 to} R ₁₈ is preferable.

The site to which the epoxy group is bonded through the divalent linking group or the single bond may be any of R _{11 to} R ₁₈ . When the epoxy group is introduced by Friedel-Crafts reaction using epichlorohydrin or the like, the epoxy group is easily introduced into the sites of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₈ that are easily attacked. .

  The number of the epoxy groups in the general formula (II) is preferably 1 to 3, more preferably 1 or 2, and most preferably 1. When the number of the epoxy groups is one, the epoxy equivalent can be increased most.

In general formula (II), at least one branched alkyl group is present, and the site to which it is bonded may be any of R _{11 to} R ₁₈ . In order to reduce the water absorption of the resin molded product (crosslinked epoxy resin) according to the present invention, it is effective to increase the bulk of the epoxy resin. From this viewpoint, the site to which the branched alkyl group is bonded is preferably R ₁₁ , R ₁₂ , R ₁₃ or R ₁₈ bonded to a benzene ring or a naphthalene ring. When these sites are the branched alkyl groups, the bulk of the epoxy resin can be further increased, and the water absorption of the crosslinked epoxy resin obtained after curing can be further reduced. When the branched alkyl group is introduced by Friedel-Crafts reaction using an alkyl halide, the branched chain is introduced into the site of R ₁₁ , R ₁₂ , R ₁₃ or R ₁₈ that is easily attacked. Alkyl groups are easily introduced.

The number of the branched alkyl groups in the general formula (II) is preferably 2 to 7, more preferably 3 to 7, further preferably 4 to 7, particularly preferably 5 to 7, and most preferably 6 or 7. .
The larger the number of branched alkyl groups, the higher the hydrophobicity and epoxy equivalent of the epoxy resin, and the higher the bulk of the epoxy resin is preferable.

The branched alkyl group is not particularly limited as long as it has 3 to 8 carbon atoms, and is preferably an isopropyl group, a t-butyl group, or an amyl group, and more preferably a t-butyl group. is there. In addition, some or all of the hydrogen atoms bonded to the branched alkyl group may be substituted with fluorine.
Since these branched alkyl groups are bulky, the hydrophobicity and epoxy equivalent of the epoxy resin can be increased, and appropriate rigidity can be imparted to improve toughness. Further, in the crosslinked epoxy resin obtained by curing these epoxy resins having branched chain alkyl groups, the bulky alkyl group fills the void at the molecular level that can be formed between the main chains of the crosslinked polymer. Thus, it is possible to prevent water molecules from entering the resin. As a result, the water absorption of the crosslinked epoxy resin can be further reduced.

In the general formula (II), among R _{11 to} R ₁₈ , those that are not the epoxy group or the branched alkyl group are hydrogen atoms, and 0 to 6 sites can be hydrogen atoms. From the viewpoint of increasing the hydrophobicity and epoxy equivalent of the epoxy resin, the smaller the number of R _{11 to} R _{18 that} are hydrogen atoms, the better.

The molecular weight of the epoxy resin represented by the general formula (II) is not particularly limited, but is preferably 300 to 6000, and more preferably 600 to 4500.
If it is below the lower limit of the above range, water resistance may not be exhibited. Moreover, when it is more than the upper limit of the said range, rigidity will increase too much, toughness may fall and impact resistance may deteriorate.
The molecular weight is a mass average molecular weight (Mw) converted based on polystyrene in GPC.

  As a suitable thing of the epoxy resin represented by general formula (II), the epoxy resin represented by following Chemical formula (2) can be illustrated, for example. Note that both ends of the epoxy resin represented by the chemical formula (2) are hydrogen atoms.

<Solvent>
In the resin composition according to the present invention, the content of the epoxy resin represented by the general formula (I) or the general formula (II) may be appropriately adjusted according to the use of the crosslinked epoxy resin obtained after curing, for example, What is necessary is just to adjust in the range of 20-100 weight% (wt%). In order to adjust the concentration, the epoxy resin composition may contain a solvent.

  The solvent is not particularly limited, and a known solvent used for diluting a known epoxy resin can be used. For example, toluene, methyl ethyl ketone, acetone, methyl isobutyl ketone, n-hexane, methanol, ethanol, isopropanol and the like can be mentioned. These may be used alone or in combination of two or more.

<Curing agent>
The resin composition according to the present invention includes (B) a curing agent represented by the following general formula (III) or general formula (IV).
Since the hydrophobic branched alkyl group is introduced into the curing agent in the same manner as the epoxy resin, the hydrophobicity of the crosslinked epoxy resin obtained by curing the composition containing the curing agent and the epoxy resin is improved. It can be further increased and its water absorption can be reduced. Further, since the skeleton structure (main chain structure) of the curing agent is similar to the skeleton structure of the epoxy resin, the compatibility is excellent. For this reason, the storage stability of the resin composition obtained by mixing the curing agent and the epoxy resin can be improved.
One type of curing agent specifically described below may be used alone, or two or more types may be used in combination.

<Curing agent represented by general formula (III)>

In formula (III), R _{21 to} R ₂₇ each independently represent a nucleophilic group, a branched alkyl group or a hydrogen atom; n _{21 to} n ₂₃ each independently represents 0 to 3 An integer; the number of the nucleophilic groups in the formula is 1 to 3; and the number of the branched alkyl groups in the formula is one or more.
The branched alkyl group preferably has 3 to 8 carbon atoms. Further, some or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. By using a branched alkyl group substituted with a fluorine atom, the water absorption of the resin molded product according to the present invention can be sometimes lowered.

  Both ends of the curing agent represented by the general formula (III) are groups derived from the monomer used when the curing agent is synthesized, and are usually hydrogen atoms. However, the hydrogen atoms at both ends may be substituted with other substituents of the type that do not impair the effects of the present invention (for example, the branched alkyl group).

R _{21 to} R ₂₇ are preferably the epoxy group or the branched alkyl group.
The n _{21 to} n ₂₃ are preferably an integer of 1 to 3, and preferably an integer of 1 or 2.

  The nucleophilic group is not particularly limited as long as it is a nucleophilic group capable of ring-opening the epoxy group of the epoxy resin, and a functional group having a lone electron pair is preferable. Examples of the nucleophilic group include a hydroxyl group, an amino group, a thiol group, and a carboxyl group. Among these, a hydroxyl group or an amino group suitable for a reaction in which an epoxy group is opened and crosslinked is preferable. The nucleophilic group may be bonded via a linking group. As the linking group, the divalent linking group can be exemplified as a preferable one.

In general formula (III), the site to which the nucleophilic group is bonded may be any of R _{21 to} R ₂₇ , but from the viewpoint of enhancing the reactivity of crosslinking, R ₂₁ , R ₂₂ or R ₂₃ is The nucleophilic group is preferred. In addition, the said nucleophilic group can be introduce | transduced into these sites with a well-known synthesis method.

  The number of the nucleophilic groups in the general formula (III) is preferably 1 or 2, and more preferably 1. Since the crosslinking point after the crosslinking reaction of the nucleophilic group has high polarity, it is preferable that the number of the nucleophilic group is small in order to increase the hydrophobicity of the crosslinked epoxy resin and decrease the water absorption.

In the present specification, the nucleophilic group equivalent means the mass (g / eq) of a resin having one nucleophilic group equivalent, for example, {curing represented by general formula (III) or general formula (IV) Molecular weight of agent} / {number of nucleophilic groups in general formula (III) or general formula (IV)}. Here, when the nucleophilic group is, for example, a hydroxyl group, the nucleophilic group equivalent can be read as OH equivalent (hydroxyl equivalent). It can be said that the larger the nucleophilic group equivalent, the more hydrophobic the curing agent. Therefore, it is preferable that the curing agent of the present invention has a higher nucleophilic group equivalent.
In addition, the said molecular weight at the time of calculating a nucleophilic group equivalent is a formula weight calculated from a chemical formula.

In general formula (III), at least one branched alkyl group is present, and the site to which it is bonded may be any of R _{21 to} R ₂₇ . In order to reduce the water absorption of the resin molded product (crosslinked epoxy resin) according to the present invention, it is effective to increase the bulk of the epoxy resin. From this point of view, the site to which the branched alkyl group is bonded is preferably R ₂₁ , R ₂₂ or R ₂₃ bonded to the aromatic ring. When these sites are the branched alkyl groups, the bulk of the curing agent can be further increased, and the water absorption of the crosslinked epoxy resin obtained after curing can be further reduced. When the branched alkyl group is introduced by Friedel-Crafts reaction using alkyl halide, the branched alkyl group is present at the sites of R ₂₁ , R ₂₂ and R ₂₃ that are easily attacked. Easy to be introduced.

The curing agent represented by the general formula (III) constitutes a crosslinked epoxy resin after the crosslinking reaction, and affects the properties of the crosslinked epoxy resin. In particular, the type and number of the branched alkyl groups can have a great influence.
The number of the branched alkyl groups in the general formula (III) is preferably 2 to 6, more preferably 3 to 6, still more preferably 4 to 6, and particularly preferably 5 or 6.
The larger the number of branched alkyl groups, the higher the hydrophobicity and epoxy equivalent of the curing agent, and the more the bulk of the curing agent can be increased.

  The description of the branched alkyl group is the same as the description of the branched alkyl group in the general formula (I) described above, and will be omitted.

The molecular weight of the curing agent represented by the general formula (III) is not particularly limited, but is preferably 300 to 6000, and more preferably 600 to 4500.
If it is below the lower limit of the above range, water resistance may not be exhibited. Moreover, when it is more than the upper limit of the said range, rigidity will increase too much, toughness may fall and impact resistance may deteriorate.
The molecular weight is a mass average molecular weight (Mw) converted based on polystyrene in GPC.

  Suitable examples of the curing agent represented by the general formula (III) include a curing agent represented by the following chemical formula (3). Note that both ends of the curing agent represented by the chemical formula (3) are hydrogen atoms.

<Curing agent represented by general formula (IV)>

In the general formula (IV), R _{31 to} R ₃₈ each independently represents a nucleophilic group, a branched alkyl group or a hydrogen atom; n _{31 to} n ₃₃ and n ₃₈ each independently represents 0 to The number of the nucleophilic groups in the formula is 1 to 3; the number of the branched alkyl groups in the formula is 1 or more.
The branched alkyl group preferably has 3 to 8 carbon atoms. Further, some or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. By using a branched alkyl group substituted with a fluorine atom, the water absorption of the resin molded product according to the present invention can be sometimes lowered.

  Both ends of the curing agent represented by the general formula (IV) are groups derived from the monomer used for synthesizing the curing agent, and are usually hydrogen atoms. However, the hydrogen atoms at both ends may be substituted with other substituents of the type that do not impair the effects of the present invention (for example, the branched alkyl group).

R _{31 to} R ₃₈ are preferably the epoxy group or the branched alkyl group.
The n _{31 to} n ₃₃ and n ₃₈ are preferably an integer of 1 to 3, and preferably an integer of 1 or 2.

  The nucleophilic group is not particularly limited as long as it is a nucleophilic group capable of ring-opening the epoxy group of the epoxy resin, and a functional group having a lone electron pair is preferable. Examples of the nucleophilic group include a hydroxyl group, an amino group, a thiol group, and a carboxyl group. Among these, a hydroxyl group or an amino group suitable for a reaction in which an epoxy group is opened and crosslinked is preferable. The nucleophilic group may be bonded via a linking group. As the linking group, the divalent linking group can be exemplified as a preferable one.

In general formula (IV), the site to which the nucleophilic group is bonded may be any of R _{31 to} R ₃₈ , but from the viewpoint of enhancing the reactivity of crosslinking, R ₃₁ , R ₃₂ , R ₃₃ or it is preferred that R ₃₈ is the nucleophilic group. In addition, the said nucleophilic group can be introduce | transduced into these sites with a well-known synthesis method.

  The number of the nucleophilic groups in the general formula (IV) is preferably 1 or 2, and more preferably 1. Since the crosslinking point after the crosslinking reaction of the nucleophilic group has high polarity, it is preferable that the number of the nucleophilic group is small in order to increase the hydrophobicity of the crosslinked epoxy resin and decrease the water absorption.

In general formula (IV), at least one branched alkyl group is present, and the bonding site may be any of R _{31 to} R ₃₈ . In order to reduce the water absorption of the resin molded product (crosslinked epoxy resin) according to the present invention, it is effective to increase the bulk of the curing agent. From this viewpoint, the site to which the branched alkyl group is bonded is preferably R ₃₁ , R ₃₂ , R ₃₃ or R ₃₈ bonded to a benzene ring or a naphthalene ring. When these sites are the branched alkyl groups, the bulk of the curing agent can be further increased, and the water absorption of the crosslinked epoxy resin obtained after curing can be further reduced. When the branched alkyl group is introduced by Friedel-Crafts reaction using an alkyl halide, the branched chain is introduced into the site of R ₃₁ , R ₃₂ , R ₃₃ or R ₃₈ that is easily attacked. Alkyl groups are easily introduced.

The curing agent represented by the general formula (IV) constitutes a crosslinked epoxy resin after the crosslinking reaction, and affects the properties of the crosslinked epoxy resin. In particular, the type and number of the branched alkyl groups can have a great influence.
The number of the branched alkyl groups in the general formula (IV) is preferably 2 to 7, more preferably 3 to 7, still more preferably 4 to 7, particularly preferably 5 to 7, and most preferably 6 or 7. .
The larger the number of branched alkyl groups, the higher the hydrophobicity and epoxy equivalent of the epoxy resin, and the higher the bulk of the epoxy resin is preferable.

  The description of the branched alkyl group is the same as the description of the branched alkyl group in the general formula (II) described above, and will be omitted.

The molecular weight of the curing agent represented by the general formula (IV) is not particularly limited, but is preferably 300 to 6000, and more preferably 600 to 4500.
If it is below the lower limit of the above range, water resistance may not be exhibited. Moreover, when it is more than the upper limit of the said range, rigidity will increase too much, toughness may fall and impact resistance may deteriorate.
The molecular weight is a mass average molecular weight (Mw) converted based on polystyrene in GPC.

  As a suitable thing of the hardening | curing agent represented by general formula (IV), the hardening | curing agent represented by following Chemical formula (4) can be illustrated, for example. Note that both ends of the curing agent represented by the chemical formula (4) are hydrogen atoms.

  Other curing agents may be used in combination as long as the effects of the present invention are not impaired. Other usable curing agents include amine compounds, acid anhydride compounds, amide compounds, phenol compounds, and the like. More specifically, for example, a polyamide resin synthesized from dimer of diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, linolenic acid and ethylenediamine, phthalic anhydride, trimellitic anhydride, Pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolac, and modified products thereof, imidazole BF3-amine complex, guanidine derivative, and the like. These may be used alone or in combination of two or more.

  The curing agent contained in the resin composition of the present invention is preferably mixed in an equimolar amount with the epoxy resin to be cured in order to make the crosslinking degree of the crosslinked epoxy resin sufficient. Specifically, as a suitable mixing ratio (molar ratio), epoxy resin: curing agent = 1.8: 1.0 to 1.0: 1.8 is preferable, and epoxy resin: curing agent = 1.5: 1. 0.0 to 1.0: 1.5 is more preferable, epoxy resin: curing agent = 1.2: 1.0 to 1.0: 1.2 is more preferable, and epoxy resin: curing agent = 1: 1 is the most. preferable.

<Method for producing resin composition>
The epoxy resin and the curing agent can be synthesized by a known method such as Friedel-Crafts reaction using commercially available raw materials. In addition, the number of n _{1 to} n ₃ , n _{11 to} n ₁₃ , n ₁₈ , n _{21 to} n ₂₃ , n _{31 to} n ₃₃ and n ₃₈ , and R _{1 to} R ₇ , R _{11 to} R ₁₈ , R ₂₁ degree of substitution to R _27, and _R 31 _{to R 38} (introduction rate) can be adjusted raw material blending ratio of the synthesis, the reaction time and the like.

  In addition to the solvent and the curing agent, various additives may be added to the resin composition as necessary. Examples of the additive include an antioxidant, a colorant, an ultraviolet absorber, a light stabilizer, a thermal polymerization inhibitor, a leveling agent, a surfactant, a storage stabilizer, a plasticizer, a lubricant, an inorganic filler, a filler, and a wetting agent. And a property improver. When these additives are used, it is preferable that the additives meet the gist of the present invention to reduce the water absorption of the crosslinked epoxy resin.

  As long as the effects of the present invention are not impaired, other epoxy resins may be added to the epoxy resin composition of the present invention. Other epoxy resins that can be used in combination with the epoxy resin of the present invention include, for example, novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type not corresponding to general formula (I) and general formula (II) An epoxy resin, a triphenylmethane type epoxy resin, etc. are mentioned. One or more of these epoxy resins may be added to the epoxy resin composition of the present invention. The ratio in the case of adding is preferably 20 parts by weight or less with respect to 100 parts by weight of the epoxy resin composition of the present invention.

When mixing each material and manufacturing a composition, it is preferable to mix thoroughly by various means. The order of mixing the materials may be mixed while sequentially adding the materials, or may be mixed after all the materials are added, as long as the materials can be uniformly dissolved or dispersed.
The mixing method is not particularly limited, and for example, a known method using a kneader, an extruder, a roll, a stirrer, a stirring blade, a ball mill, a stirrer, an ultrasonic disperser, an ultrasonic homogenizer, a revolving mixer, or the like is applied. good.
What is necessary is just to set mixing conditions, such as mixing temperature and mixing time suitably according to various methods. Usually, the temperature during mixing is preferably 10 to 50 ° C., and the total mixing time is preferably 30 to 90 minutes.

<< Resin molding >>
The resin molded product according to the present invention is obtained by molding a crosslinked epoxy resin obtained by crosslinking the resin composition into a desired shape.
The method for crosslinking the resin composition is not particularly limited, and a known epoxy resin crosslinking method (curing method) can be applied. The resin composition can be crosslinked by, for example, heat curing treatment. At this time, it is preferable to add a curing accelerator in order to accelerate the crosslinking reaction.

The heating temperature of the thermosetting treatment is not particularly limited, and is preferably, for example, 80 to 250 ° C, more preferably 120 to 220 ° C, and still more preferably 140 to 200 ° C.
When the thermosetting treatment is performed at the preferred temperature, the treatment time can be usually 0.5 to 24 hours.

As the curing accelerator, those used for crosslinking of known epoxy resins can be applied. For example, imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2- (Dimethylaminomethyl) phenol, tertiary amines such as 1,8-diaza-bicyclo (5,4,0) undecene-7, phosphines such as triphenylphosphine, metal compounds such as tin octylate, etc. It is done.
The curing accelerator is used as necessary in an amount of 0.1 to 5.0 parts by weight (phr) with respect to 100 parts by weight of the epoxy resin. These may be used alone or in combination of two or more.

  A method for molding a crosslinked epoxy resin obtained by crosslinking the resin composition is not particularly limited, and a known method can be applied. For example, a method of pouring the resin composition into a mold to crosslink, a method of extruding while heat curing, and the like can be mentioned.

<< Cable >>
The cable of the present invention is formed by forming a cross-linked epoxy resin obtained by curing the resin composition according to the present invention so as to cover a conductor and forming an insulating layer that electrically insulates the conductor.
The insulating layer may be a single layer or a multilayer. The thickness of the insulating layer is not particularly limited, and may be formed with a necessary thickness according to the application. By applying the above-mentioned epoxy resin composition to the conductor to be insulated and thermally curing, a cable in which the conductor is coated with a crosslinked epoxy resin can be produced.

The use of the cable according to the present invention is not particularly limited, but for example, insulated wires, electronic device wiring wires, automotive wires, device wires, power cords, outdoor distribution insulated wires, power cables, control cables, and communication cables Various cables (electric wires) such as a cable, an instrumentation cable, a signal cable, a movement cable, and a ship cable are included.
The resin molded product (crosslinked epoxy resin) according to the present invention can be applied to uses other than cable insulation materials. For example, sheathing materials, tapes, cable accessories such as cases and plugs, electric conduits, and wiring ducts. It can also be applied to electrical materials such as bus ducts, agricultural sheets, water hoses, gas pipe covering materials, building interior materials, floor materials, adhesives, paints, resists, optical materials, and semiconductor electronic device sealing materials. is there.

[Example 1, Comparative Examples 1-3]
<Synthesis of epoxy resin>
As shown in the following reaction formula (A), 100 parts by weight of a raw material epoxy resin (manufactured by Mitsubishi Chemical Corporation) is dissolved in 100 parts by weight of toluene, heated to 45 ° C. in a nitrogen atmosphere, and 5 parts by weight of 37 wt% concentrated hydrochloric acid. Was added over 30 minutes with an isobaric dropping funnel and allowed to react for 2 hours to open the ring. This solution was extracted three times with toluene, and the solvent was removed by heating under reduced pressure. This was dissolved in 100 parts by weight of dichloromethane, cooled to 0 ° C., 50 parts by weight of anhydrous aluminum chloride was slowly added, and the mixture was stirred for 15 minutes. A solution prepared by dissolving each alkyl halide shown in Table 1 in 100 parts by weight of dichloromethane was added dropwise at 0 ° C., stirred for 30 minutes, then warmed to room temperature and stirred overnight. After completion of the reaction, the mixture was poured into 80 parts by weight of ice water containing 10 parts by weight of 37 wt% concentrated hydrochloric acid. The mixture was stirred for 10 minutes and then extracted three times with dichloromethane. The organic phases were combined, washed with water, 20 parts by weight of a 30 wt% aqueous sodium hydroxide solution was added thereto, and the mixture was stirred at 70 ° C. for 2 hours to close the epoxy ring. This was extracted three times with dichloromethane. The organic phases were combined, washed with water and then with saturated brine. Thereafter, the solvent was removed by heating under reduced pressure. This was recrystallized with toluene to obtain an epoxy resin (prepolymer) into which the target substituent R was introduced.

<Synthesis of curing agent>
As shown in the following reaction formula (B), 100 parts by weight of a raw material curing agent (manufactured by Mitsubishi Chemical Corporation) is dissolved in 100 parts by weight of dichloromethane, cooled to 0 ° C., 50 parts by weight of anhydrous aluminum chloride is slowly added, and the mixture is mixed. Was stirred for 15 minutes. A solution prepared by dissolving each alkyl halide shown in Table 2 in 100 parts by weight of dichloromethane was added dropwise at 0 ° C., stirred for 30 minutes, then warmed to room temperature and stirred overnight. After completion of the reaction, the mixture was poured into 80 parts by weight of ice water containing 10 parts by weight of 37 wt% concentrated hydrochloric acid. The mixture was stirred for 10 minutes and then extracted three times with dichloromethane. The organic phases were combined, washed with water and then with saturated brine. Thereafter, the solvent was removed by heating under reduced pressure. This was recrystallized with toluene to obtain a curing agent into which the target substituent R was introduced.
The introduction rate and the substitution position of the substituent R in the obtained curing agent were confirmed by NMR or the like as necessary.

<Preparation of epoxy resin composition>
Each epoxy resin composition was prepared by blending each synthesized epoxy resin, each curing agent, and triphenylphosphine (TPP) in the proportions shown in Table 3.

[Comparative Example 4]
An epoxy resin (manufactured by Mitsubishi Chemical Corporation) and a curing agent (manufactured by Mitsubishi Chemical Corporation), which were used as raw materials in the synthesis of Example 1 and Comparative Examples 1 to 3 and without introducing a substituent, were used as they were. The epoxy resin composition was blended and adjusted at the ratio shown in Table 4.

<< Synthesis of cross-linked epoxy resin >>
Each of the prepared compositions was applied to a flat-bottom bat, heated at 160 ° C. for 2 hours, and further heated at 180 ° C. for 6 hours to obtain a sheet made of a crosslinked epoxy resin having a size of 50 mm × 50 mm × 1 mm.

<< Evaluation of water absorption >>
Each sheet of Example 1 and Comparative Examples 1 to 4 was immersed in 100 ° C. ion exchange water for 24 hours, and the water content before and after the immersion was measured by electrolytic titration (Karl Fischer coulometric titration). The water absorption was evaluated. CA-100 (moisture measuring device) and VA-100 (vaporizer) manufactured by Mitsubishi Chemical were used as measuring devices. The results are shown in Table 5.

From the above, the water absorption of the resin molded product (crosslinked epoxy resin) of Example 1 according to the present invention is lower than that of the crosslinked epoxy resin (Comparative Examples 1 to 4) of the comparative example. From Example 1 and Comparative Examples 1 to 4, the higher the hydrophobicity of the introduced substituent R, that is, the higher the epoxy equivalent and the OH equivalent by introducing a branched alkyl group, the lower the water absorption. Obviously it can be. Furthermore, from the results of Example 1 and Comparative Example 1 in which the epoxy equivalent and the OH equivalent amount are the same, by introducing a branched alkyl group to increase the bulk of the substituent R, the water absorption is reduced. It is understood that you can.
Therefore, since the cable using the resin molded product of the present invention as an insulating layer has a small proportion of absorbing moisture in the usage environment during use, it is clear that deterioration due to moisture absorption is reduced.

Claims (5)

(A) an epoxy resin represented by general formula (I) or general formula (II);
(B) a curing agent represented by general formula (III) or general formula (IV),
(C) Any one or more of R _{1 to} R ₇ or any one or more of R _{11 to} R ₁₈ is a branched alkyl group.

[Wherein, R _{1 to} R ₇ each independently represents a branched alkyl group, a hydrogen atom, a divalent linking group or an epoxy group bonded via a single bond; n _{1 to} n ₃ each represents It is an integer of 0-3 independently; The number of the said epoxy group in a formula is 1-3. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]

[Wherein, R _{11 to} R ₁₈ each independently represents a branched alkyl group, a hydrogen atom, a divalent linking group or an epoxy group bonded via a single bond; n _{11 to} n ₁₃ and n ₁₈ is each independently an integer of 0 to 3; the number of the epoxy groups in the formula is 1 to 3. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]

[Wherein, R _{21 to} R ₂₇ each independently represent a nucleophilic group, a branched alkyl group or a hydrogen atom; n _{21 to} n ₂₃ each independently represents an integer of 0 to 3; The number of the nucleophilic groups in the formula is 1 to 3; the number of the branched alkyl groups in the formula is one or more. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]

[Wherein, R _{31 to} R ₃₈ each independently represents a nucleophilic group, a branched alkyl group or a hydrogen atom; n _{31 to} n ₃₃ and n ₃₈ each independently represent an integer of 0 to 3; The number of the nucleophilic groups in the formula is 1 to 3; the number of the branched alkyl groups in the formula is one or more. Part or all of the hydrogen atoms constituting the branched alkyl group may be substituted with fluorine atoms. ]   The resin composition according to claim 1, wherein the branched alkyl group is a t-butyl group.   The resin composition according to claim 1 or 2, wherein the number of the epoxy groups in the general formula (I) and the general formula (II) is one.   A resin molded product obtained by crosslinking and molding the resin composition according to any one of claims 1 to 3. A conductor and an insulating layer covering the conductor;
The cable, wherein the insulating layer is made of the resin molded product according to claim 4.