JP7655323B2 - Composition for sealing coated electric wire and coated electric wire - Google Patents

Description

The present invention relates to a composition for sealing coated electric wires, and a coated electric wire. More specifically, the present invention relates to a composition that is widely used as a sealant for coated electric wires in wiring of various electric systems such as automobiles, home appliances, and OA (Office Automation) equipment, and to a coated electric wire comprising a cured product of the composition.

Various electrical systems in automobiles, home appliances, office equipment, etc. are wired with electric wires, and the harness parts have traditionally been crimped or sealed.

2. Description of the Related Art A conventional wire harness is known from Japanese Unexamined Patent Publication No. 2003-233696.
Patent Document 1 describes a wire harness having a wire bundle in which a plurality of insulated wires, each of which has a conductor covered with a covering material made of an insulator, are bundled together, and a conductor exposed portion in which a part of the covering material has been removed to expose the internal conductor is covered with a water-sealing agent made of a photocurable resin, and the surface of the water-sealing agent is covered with a light-transmitting protective sheet. The wire harness is characterized in that the water-sealing agent is capable of curing in places where light does not reach, and is formed from a composition containing a photocurable resin and a chain transfer agent.

Furthermore, as a conventional anticorrosive material, the one described in Patent Document 2 is known.
Patent Document 2 describes an anticorrosive material that includes an ultraviolet-curable resin mainly composed of a polymerizable compound composed of at least one of a photopolymerizable (meth)acrylate monomer and a photopolymerizable (meth)acrylate oligomer, the polymerizable compound being composed of a monofunctional (meth)acrylate monomer and a bifunctional (meth)acrylate monomer in combination, or a monofunctional (meth)acrylate monomer and a bifunctional (meth)acrylate monomer in combination with at least one of a trifunctional (meth)acrylate monomer and a polyfunctional (meth)acrylate monomer having 4 or more functionalities, and that has a viscosity of 18,900 mPa·s or less at 25° C. as measured in accordance with JIS Z8803.

JP 2014-116196 A JP 2016-204476 A

An object of the present invention is to provide a composition for sealing a covered electric wire, which provides an electric wire seal having excellent heat resistance for the resulting covered electric wire.
Another object of the present invention is to provide a covered electric wire provided with a cured product of the above-mentioned composition for sealing a covered electric wire.

Means for solving the above problems include the following aspects.
<1> A composition for sealing a coated electric wire, comprising: as a component (A), a compound having an isocyanate group; as a component (B), a compound having a (meth)acrylic group; and as a component (C), a photopolymerization initiator, wherein the content of the component (A) exceeds 50 mass% with respect to the total mass of the composition.
<2> The composition for sealing a coated electric wire according to <1>, wherein the component (A) contains an isocyanate prepolymer.
<3> The composition for sealing a coated electric wire according to <1> or <2>, wherein the component (A) contains a compound in which an isocyanate group is directly bonded to an aromatic ring.
<4> The composition for sealing a coated electric wire according to any one of <1> to <3>, wherein the composition contains a moisture curing catalyst.
<5> The composition for sealing a coated electric wire according to any one of <1> to <4>, wherein the content of the component (A) is 60 mass% or more based on the total mass of the composition.
<6> The composition for sealing a coated electric wire according to any one of <1> to <5>, wherein the content of the component (B) is 15 mass% or more based on the total mass of the composition.
<7> The composition for sealing a coated electric wire according to any one of <1> to <6>, wherein the component (B) includes a compound having two or more (meth)acrylic groups.
<8> The composition for coated electric wire sealing according to any one of <1> to <7>, wherein the content of the compound having two or more (meth)acrylic groups is 0.1% by mass to 40% by mass, based on the total mass of the composition.
<9> The composition for sealing a coated electric wire according to any one of <1> to <8>, wherein the component (A) includes a compound having an isocyanate group and a (meth)acrylic group.
<10> The composition for sealing a coated electric wire according to <9>, wherein the content of the compound having an isocyanate group and a (meth)acrylic group is 5 mass% or more based on the total mass of the composition.
<11> A composition for sealing a coated electric wire, comprising: as a component (A'), a compound having an isocyanate group and a (meth)acrylic group; and as a component (C), a photopolymerization initiator, wherein the content of the component (A') is 25 mass% or more relative to the total mass of the composition.
<12> The composition for sealing a coated electric wire according to <11>, further comprising a moisture curing catalyst.
<13> A covered electric wire comprising a cured product of the composition for covered electric wire sealing according to any one of <1> to <12>.

According to the present invention, it is possible to provide a composition for sealing a covered electric wire, which provides an electric wire seal having excellent heat resistance for the resulting covered electric wire.
Furthermore, according to the present invention, there can be provided a covered electric wire comprising a cured product of the above-mentioned composition for sealing a covered electric wire.

The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, the word "to" is used to mean that the numerical values before and after it are included as the lower limit and upper limit.
In the numerical ranges described in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in another stepwise manner. In addition, in the numerical ranges described in this specification, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.
In the present invention, "mass %" and "weight %" are synonymous, and "parts by mass" and "parts by weight" are synonymous.
Also, in the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.
In addition, in this specification, "(meth)acrylic" refers to both or either of acrylic and methacrylic, "(meth)acryloyl" refers to both or either of acryloyl and methacryloyl, and "(meth)acrylate" refers to both or either of acrylate and methacrylate.
The present invention will be described in detail below.

(Composition for sealing coated electric wire)
A first embodiment of the composition for sealing a coated electric wire (hereinafter, also simply referred to as the "composition") of the present invention comprises, as component (A), a compound having an isocyanate group, as component (B), a compound having a (meth)acrylic group, and as component (C), a photopolymerization initiator, and the content of the component (A) exceeds 50 mass% with respect to the total mass of the composition.
A second embodiment of the composition for sealing coated electric wires of the present invention comprises, as component (A'), a compound having an isocyanate group and a (meth)acrylic group, and as component (C), a photopolymerization initiator, and the content of component (A') is 25 mass% or more relative to the total mass of the composition.
In this specification, unless otherwise specified, simply referring to the "sealing composition for coated electric wires of the present invention" or the "composition of the present invention" refers to both the first embodiment and the second embodiment. Furthermore, unless otherwise specified, simply referring to "component (C)" or the like refers to all of the components (C) of the first embodiment and the second embodiment.

Furthermore, the composition for sealing coated electric wires of the present invention can be suitably used as a composition for sealing coated electric wires in wire harnesses of automobiles, home appliances, office automation equipment, etc., and can be particularly suitably used as a composition for sealing coated electric wires in wire harnesses of automobiles.

As a result of extensive investigations, the present inventors have found that, by adopting the above-mentioned configuration, it is possible to provide a composition for sealing a covered electric wire which provides an electric wire seal having excellent heat resistance.
The mechanism of action behind this excellent effect is not clear, but is presumed to be as follows.
Not only does the composition photocure due to the (meth)acrylic groups of component (B) or component (A'), and component (C), but by containing more than 50 mass% of component (A) or containing 25 mass% or more of component (A'), a dark reaction further proceeds in the presence of moisture after photocure, which is believed to further improve the strength and thermal stability of the cured product and result in a wire seal for the insulated electric wire that has excellent heat resistance.

<Component (A): Compound Having an Isocyanate Group>
A first embodiment of the composition for sealing a coated electric wire of the present invention contains a compound having an isocyanate group as component (A), and the content of component (A) exceeds 50 mass% with respect to the total mass of the composition.
The second embodiment of the composition for coated electric wire sealing of the present invention may contain a compound having an isocyanate group other than the compound having an isocyanate group and a (meth)acrylic group (A'), and from the viewpoint of electric wire sealing property, it is preferable that the total content of the component (A') and the compound having an isocyanate group other than the component (A') exceeds 50 mass% with respect to the total mass of the composition. Note that both the component (A') and the isocyanate compound other than the component (A') are broadly included in the component (A).

The (A) component may be a compound having only one isocyanate group (also referred to as a "monofunctional isocyanate compound") or a compound having two or more isocyanate groups (also referred to as a "polyfunctional isocyanate compound" or "polyisocyanate compound"). From the viewpoint of the heat resistance and cold/heat shock resistance (also referred to as "thermal shock resistance") of the wire seal, it is preferable to contain a compound having two or more isocyanate groups.
Also, a prepolymer having an isocyanate group (also called an "isocyanate prepolymer") can be suitably used as the component (A). Suitable examples of the prepolymer having an isocyanate group include a multimer of a polyisocyanate compound, and an addition reaction product of a polyol compound, a polyamine compound, or an aminoalcohol compound with a polyisocyanate compound.

The polymer of the polyisocyanate compound is not particularly limited, but examples thereof include biuret, allophanate, and isocyanurate.
The adduct is included in the addition reaction product of the polyol compound, polyamine compound or aminoalcohol compound and the polyisocyanate compound.

Examples of the polyisocyanate compound include aliphatic polyisocyanates having no alicyclic group (hereinafter also simply referred to as "aliphatic polyisocyanates"), aliphatic polyisocyanates having an alicyclic group (hereinafter also referred to as "alicyclic polyisocyanates"), polyisocyanates having a heterocycle, and aromatic polyisocyanates.
Among these, from the viewpoint of the heat resistance and cold-heat shock resistance of the wire seal, it is preferable for component (A) to contain a compound in which an isocyanate group is directly bonded to an aromatic ring, it is more preferable for component (A) to contain an aromatic polyisocyanate, and it is particularly preferable for component (A) to contain an aromatic isocyanate prepolymer.

Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.
Examples of the alicyclic polyisocyanate include hydrogenated tolylene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate.
Examples of the polyisocyanate having a heterocycle include a hexamethylene diisocyanate trimer and an isophorone diisocyanate trimer.
Examples of aromatic diisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, paraphenylene diisocyanate, and 1,5-naphthalene diisocyanate.

As the polyol compound used to prepare the prepolymer, a diol compound is preferred, and low molecular weight diols, diols having a polyester skeleton, diols having a polyether skeleton, and diols having a polycarbonate skeleton are preferably used.

Examples of low molecular weight diols include ethylene glycol, propylene glycol, cyclohexanedimethanol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol.
Examples of the diol having a polyester skeleton include an esterification reaction product between a diol component such as the above-mentioned low molecular weight diol or polycaprolactone diol and an acid component such as a dicarboxylic acid or an anhydride thereof.
Examples of dicarboxylic acids or anhydrides thereof include adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and terephthalic acid, as well as anhydrides thereof.
Examples of the diol having a polyether skeleton include polyethylene glycol, polypropylene glycol, polyetramethylene glycol, etc. Examples of the diol having a polycarbonate skeleton include a reaction product of at least one diol selected from the group consisting of the low molecular weight diols and bisphenols such as bisphenol A, with ethylene carbonate and a dialkyl carbonate such as dibutyl carbonate, etc.

Preferred examples of the polyisocyanate compounds used to prepare the prepolymer include the polyisocyanate compounds described above.

The weight average molecular weight (Mw) of the prepolymer is not particularly limited, but is preferably from 1,000 to 60,000, more preferably from 1,000 to 55,000, even more preferably from 1,000 to 50,000, and particularly preferably from 1,500 to 40,000.
In the present invention, Mw is a value calculated by converting the molecular weight measured by gel permeation chromatography into polystyrene equivalent value.

<<Component (A'): Compound Having an Isocyanate Group and a (Meth)acrylic Group>>
A second embodiment of the composition for sealing coated electric wires of the present invention comprises, as component (A'), a compound having an isocyanate group and a (meth)acrylic group, and the content of component (A') is 25 mass% or more relative to the total mass of the composition.
A first embodiment of the composition for sealing a coated electric wire of the present invention may contain, as component (A), a compound having an isocyanate group and a (meth)acrylic group (component (A')), and preferably contains a compound having an isocyanate group and a (meth)acrylic group.

The isocyanate group in the compound having an isocyanate group and a (meth)acrylic group may be an aliphatic isocyanate group or an aromatic isocyanate group, but is preferably an aliphatic isocyanate group.
In the compound having an isocyanate group and a (meth)acrylic group, the (meth)acrylic group is preferably a (meth)acryloxy group from the viewpoint of the heat resistance and thermal shock resistance of the wire seal.

The compound having an isocyanate group and a (meth)acrylic group is preferably a prepolymer having an isocyanate group and a (meth)acrylic group.
Suitable examples of the prepolymer having an isocyanate group and a (meth)acrylic group include prepolymers obtained by reacting a portion of the isocyanate groups of the isocyanate prepolymer with a monofunctional or polyfunctional (meth)acrylate compound having a hydroxyl group.
Examples of monofunctional (meth)acrylate compounds having a hydroxy group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, hydroxyhexyl (meth)acrylate, and hydroxyoctyl (meth)acrylate.
Examples of polyfunctional (meth)acrylate compounds having a hydroxy group include trimethylolpropane di(meth)acrylate, di- or tri(meth)acrylate of pentaerythritol, di- or tri(meth)acrylate of ditrimethylolpropane, and di-, tri-, tetra- or penta(meth)acrylate of dipentaerythritol.

The weight average molecular weight (Mw) of component (A') is not particularly limited, but is preferably 1,000 to 60,000, more preferably 1,000 to 55,000, even more preferably 1,000 to 50,000, and particularly preferably 1,500 to 40,000.

The component (A') can be produced, for example, by an addition reaction of a polyol compound, a polyisocyanate compound, and a (meth)acrylate compound having a hydroxy group, or, in the case of an adduct, by an addition reaction of a polyisocyanate compound and a (meth)acrylate compound having a hydroxy group.
These addition reactions can be carried out without a catalyst. However, in order to efficiently proceed with the reaction, a tin-based catalyst such as dibutyltin dilaurate, an amine-based catalyst such as triethylamine, or a metal complex-based catalyst such as a zinc complex or an iron complex may be added.

The component (A') may use one type alone, or two or more types in combination.
In the second embodiment of the composition for coated electric wire sealing of the present invention, the content of component (A') is 25 mass% or more based on the total mass of the composition, and from the viewpoint of the heat resistance and cold-heat shock resistance of the electric wire seal, it is preferably 25 mass% to 99.5 mass%, more preferably 30 mass% to 85 mass%, and particularly preferably 65 mass% to 85 mass%.
The content of component (A') in the first embodiment of the composition for coated electric wire sealing of the present invention is preferably 5 mass% or more, more preferably 5 mass% to 40 mass%, and particularly preferably 8 mass% to 25 mass%, based on the total mass of the composition, from the viewpoint of the heat resistance and thermal shock resistance of the electric wire seal.

The component (A) may use one type alone, or two or more types in combination.
The content of component (A) in the first embodiment of the composition for coated electric wire sealing of the present invention exceeds 50 mass% relative to the total mass of the composition, and from the viewpoints of the heat resistance and cold-heat shock resistance of the electric wire seal, it is preferably 55 mass% to 90 mass%, more preferably 55 mass% to 85 mass%, and particularly preferably 58 mass% to 80 mass%.
In the second embodiment of the composition for coated electric wire sealing of the present invention, the total content of component (A') and compounds having an isocyanate group other than component (A') is, from the viewpoint of electric wire sealing properties, preferably more than 50 mass%, more preferably 55 mass% to 99.5 mass%, and particularly preferably 65 mass% to 85 mass%, based on the total mass of the composition.

<Component (B): Compound Having a (Meth)acrylic Group>
A first embodiment of the composition for sealing a coated electric wire of the present invention contains a compound having a (meth)acrylic group as component (B).
A second embodiment of the composition for sealing a coated electric wire of the present invention may contain a compound having a (meth)acrylic group as the component (B).

Examples of the (meth)acrylic group in the component (B) include a (meth)acryloxy group, a (meth)acrylamide group, etc. Among these, from the viewpoints of curability and the heat resistance and thermal shock resistance of the wire seal, a (meth)acryloxy group is preferred.
From the viewpoint of viscosity, the component (B) preferably contains a (meth)acrylamide compound.
Furthermore, the compound having a (meth)acrylic group in the component (B) may be a compound having only one (meth)acrylic group, or a compound having two or more (meth)acrylic groups. From the viewpoints of curability and the heat resistance and thermal shock resistance of the wire seal, it is preferable to include a compound having two or more (meth)acrylic groups.

Specific examples of the component (B) include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; cycloalkyl (meth)acrylates such as isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate; phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, carbitol (meth)acrylate, ethyl carbitol (meth)acrylate (ethoxyethoxyethyl (meth)acrylate), N-vinylcaprolactone, (meth)acryloylmorpholine, glycidyl ...tetrahydrofurfuryl ( mono(meth)acrylates such as nonylphenol ethylene oxide modified (meth)acrylate, nonylphenol ethylene oxide modified (meth)acrylate, nonylphenol propylene oxide modified (meth)acrylate, 2-ethylhexyl ethylene oxide modified (meth)acrylate, and (meth)acrylate having a maleimide group; (meth)acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; (meth)acrylate oligomers such as 1,6-hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tribromophenyloxyethyl (meth)acrylate, and bis((meth)acryloxyethyl)acid phosphate; and polyester poly(meth)acrylate.
In addition to these, tri- or higher functional (meth)acrylates can also be used.
Specific examples include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and tris(2-(meth)acryloyloxyethyl)isocyanurate.

Among these, from the viewpoint of the heat resistance and thermal shock resistance of the wire seal, it is preferable that the (B) component contains at least one compound selected from the group consisting of ethyl carbitol (meth)acrylate, dimethyl (meth)acrylamide, and (meth)acryloyl morpholine, and it is more preferable that the (B) component contains at least one compound selected from the group consisting of dimethyl (meth)acrylamide and (meth)acryloyl morpholine.
Moreover, from the viewpoints of photocurability and the heat resistance and thermal shock resistance of the wire seal, the (B) component preferably contains a bifunctional (meth)acrylate compound, more preferably contains a bifunctional (meth)acrylate compound having a phosphoric acid structure, and particularly preferably contains bis((meth)acryloxyethyl) acid phosphate (the compound below, R = hydrogen atom or methyl group).

In the composition for sealing coated electric wires of the present invention, when the content of the compound having only one (meth)acrylic group is M1 and the content of the compound having two or more (meth)acrylic groups is M2, it is preferable that M1 > M2 in terms of mass ratio.
In the composition for covering an electric wire seal of the present invention, preferably in the first embodiment of the composition for covering an electric wire seal of the present invention, the content of the compound having only one (meth)acrylic group is preferably 5% by mass to 50% by mass, more preferably 5% by mass to 40% by mass, and particularly preferably 8% by mass to 35% by mass, relative to the total mass of the composition, from the viewpoints of the heat resistance and cold-heat shock resistance of the electric wire seal.
In addition, the content of the compound having two or more (meth)acrylic groups in the composition for covering electric wire sealing of the present invention, preferably in the first embodiment of the composition for covering electric wire sealing of the present invention, is, from the viewpoint of the heat resistance and cold-heat shock resistance of the electric wire seal, preferably 0.1 mass % to 40 mass %, more preferably 0.5 mass % to 30 mass %, even more preferably 1 mass % to 10 mass %, and particularly preferably 1 mass % to 5 mass %, relative to the total mass of the composition.

The component (B) may use one type alone, or two or more types in combination.
The content of the component (B) in the first embodiment of the composition for coated electric wire sealing of the present invention is, from the viewpoint of the heat resistance and thermal shock resistance of the electric wire seal, preferably 5% by mass to 50% by mass, more preferably 5% by mass to 40% by mass, and particularly preferably 8% by mass to 35% by mass, based on the total mass of the composition.
The content of the component (B) in the second embodiment of the composition for coated electric wire sealing of the present invention is, from the viewpoint of the heat resistance and thermal shock resistance of the electric wire seal, preferably 50 mass % or less, more preferably 40 mass % or less, and particularly preferably 1 mass % to 40 mass %, based on the total mass of the composition.
In addition, the content of component (B) in the composition for coated electric wire sealing of the present invention is preferably more than 10 mass % and more preferably 15 mass % or more, based on the total mass of the composition, from the viewpoints of curability and the heat resistance and thermal shock resistance of the electric wire seal.

<Component (C): Photopolymerization initiator>
The composition for sealing a coated electric wire of the present invention contains a photopolymerization initiator as the component (C).
As the photopolymerization initiator, a photoradical polymerization initiator is preferably used.
It is a photoradical polymerization initiator.
A photopolymerization initiator is a compound that generates a polymerization initiating species upon irradiation with active energy rays and initiates polymerization of a compound having a polymerizable group such as a (meth)acrylic group.
Examples of active energy rays include visible light, ultraviolet light, and X-rays. Visible light or ultraviolet light is preferred because it allows the use of inexpensive equipment.

Specific examples of the component (C) include benzyl dimethyl ketal, benzil, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, oligo[2-hydroxy-2-methyl-1-[4-1-(methylvinyl)phenyl]propanone, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl aromatic ketone compounds such as 2-methyl-1-[4-(methylthio)]phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)butan-1-one, ADEKA OPTOMER N-1414 [manufactured by ADEKA Corporation], phenyl glyoxylic acid methyl ester, ethyl anthraquinone, and phenanthrenequinone;
Benzophenone-based compounds such as benzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 4-(methylphenylthio)phenylphenylmethane, methyl-2-benzophenone, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, N,N'-tetraethyl-4,4'-diaminobenzophenone and 4-methoxy-4'-dimethylaminobenzophenone;
Acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphineate, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide;
thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 1-chloro-4-propylthioxanthone, 3-[3,4-dimethyl-9-oxo-9H-thioxanthone-2-yl]oxy]-2-hydroxypropyl-N,N,N-trimethylammonium chloride, fluorothioxanthone, and other thioxanthone-based compounds.

Among these compounds, acylphosphine oxide compounds are preferred because they have good curing properties even when exposed to active energy rays through a film that contains ultraviolet absorbers and has low transparency, and the preferred compounds are as described above.

The component (C) may use one type alone, or two or more types in combination.
The content of the (C) component is preferably 0.1 mass % to 20 mass %, more preferably 0.2 mass % to 10 mass %, and particularly preferably 0.5 mass % to 2 mass %, based on the total mass of the composition, from the viewpoints of curability and the heat resistance and thermal shock resistance of the electric wire seal.

<Moisture curing catalyst>
From the viewpoint of the heat resistance and cold-heat shock resistance of the wire seal, the composition for coated electric wire seal of the present invention preferably contains a moisture curing catalyst. By containing the moisture curing catalyst, the polymerizable groups such as (meth)acrylic groups remaining after light irradiation also undergo further polymerization reaction by moisture, and the polymerization proceeds more than with light irradiation alone.

The moisture curing catalyst is not particularly limited, and any known catalyst can be used.
Examples of moisture curing catalysts include metal salts of organic acids and carboxylic acids such as lead 2-ethyloctoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin bisacetylacetonate, dibutyltin dimethoxide, dibutyltin bis(trimethoxysilyl), butyltin tri-2-ethylhexoate, iron 2-ethylhexoate, cobalt 2-ethylhexoate, manganese 2-ethylhexoate, zinc 2-ethylhexoate, stannous caprylate, tin naphthenate, tin oleate, tin butylate, tin naphthenate, zinc naphthenate, cobalt naphthenate, and zinc stearate;
organic titanate esters such as tetrabutyl titanate, tetra-2-ethylhexyl titanate, triethanolamine titanate, tetra(isopropenyloxy)titanate, diisopropoxybis(ethyl acetoacetate)titanium, and diisopropoxybis(acetylacetone)titanium;
organic titanium compounds such as organosiloxytitanium and β-carbonyltitanium, alkoxyaluminum compounds, and quaternary ammonium salts such as benzyltriethylammonium acetate;
Lower fatty acids of alkali metals such as potassium acetate, sodium acetate, and lithium oxalate; dialkylhydroxylamines such as dimethylhydroxyamine and diethylhydroxyamine;
2,2'-dimorpholinodiethyl ether, di(2,6-dimethylmorpholinoethyl)ether, bis(2-(2,6-dimethyl-4-morpholino)ethyl)-(2-(4-morpholino)ethyl)amine, bis(2-(2,6-dimethyl-4-morpholino)ethyl)-(2-(2,6-diethyl-4-morpholino)ethyl)amine, tris(2-(4-morpholino)ethyl)amine, tris(2-(4-morpholino)propyl)amine, tris(2-(4-morpholino )butyl)amine, tris(2-(2,6-dimethyl-4-morpholino)ethyl)amine, tris(2-(2,6-diethyl-4-morpholino)ethyl)amine, tris(2-(2-ethyl-4-morpholino)ethyl)amine, and morpholine compounds such as tris(2-(2-ethyl-4-morpholino)ethylamine, di[2-(3,5-dimethylmorpholino)ethyl]ether, and N-methylmorpholine bis(2-dimethylaminoethyl)ether.
Among these compounds, morpholine compounds are preferred because they do not impair adhesion or stability and have good curing properties, and the preferred compounds are as described above.

The moisture curing catalyst may be used alone or in combination of two or more kinds.
The content of the moisture curing catalyst is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 5% by mass, and particularly preferably 0.1% by mass to 2% by mass, based on the total mass of the composition, from the viewpoint of the heat resistance and thermal shock resistance of the wire seal.

<Anaerobic curing catalyst>
The composition for sealing a coated electric wire of the present invention may contain an anaerobic curing catalyst.
The anaerobic curing catalyst is a catalyst that generates polymerization initiating species under anaerobic conditions without contact with oxygen.
The anaerobic curing catalyst is not particularly limited, and any known catalyst can be used.
Among these, it is preferable to contain an anaerobic curing accelerator and an organic peroxide, and it is particularly preferable to contain saccharin and an organic peroxide.
Examples of the anaerobic curing accelerator include organic sulfonimides, amines, and organic metal salts. As the organic sulfonimides, o-sulfobenzoic acid imides are preferred, and saccharin is particularly preferred. As the amines, diethylamine, triethylamine, N,N-dimethyl-p-toluidine, 1,2,3,4-tetrahydroquinone, and the like are preferred. Furthermore, examples of the organic metal salts include copper chloride and copper octylate.
Examples of the organic peroxide include hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, and the like, as well as diacyl peroxides, dialkyl peroxides, ketone peroxides, peroxy esters, etc. Among these, cumene hydroperoxide is preferred from the viewpoints of stability and curing speed.

The anaerobic curing catalyst may be used alone or in combination of two or more kinds.
The content of the anaerobic curing catalyst is preferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 8% by mass, and particularly preferably 0.5% by mass to 5% by mass, based on the total mass of the composition, from the viewpoint of the heat resistance and thermal shock resistance of the electric wire seal.

<Other ingredients>
The composition of the present invention may contain other components in addition to the above components. Examples of other components include known additives, such as stabilizers, polymerization accelerators, dyes, pigments, diluents, etc.
The content of the other components is not particularly limited, but is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total mass of the composition.

As the other components, a stabilizer is preferably mentioned.
As the stabilizer, a known polymerization suppressor or polymerization inhibitor can be used, such as hydroquinone or sulfurous acid gas.

As the other components, a polymerization accelerator is preferably used, and an anionic polymerization accelerator is more preferably used.
Examples of the anionic polymerization accelerator include polyalkylene oxides and derivatives thereof, crown ethers and derivatives thereof, silacrown ethers and derivatives thereof, and calixarene derivatives.

In addition to these, dyes, pigments, diluents, and fillers (such as silica particles) can also be added.

<Various physical properties of the composition or cured product>
-viscosity-
The composition for coated electric wire sealing of the present invention has a viscosity at 25°C of preferably 25 mPa·s to 20,000 mPa·s, more preferably 30 mPa·s to 10,000 mPa·s, and particularly preferably 100 mPa·s to 5,000 mPa·s, from the viewpoints of the heat resistance and thermal shock resistance of the electric wire seal.

The viscosity of the composition for sealing coated electric wires of the present invention at 25°C is measured in accordance with the measurement method using a rotational viscometer specified in JIS Z 8803 (2011) and the viscosity at 25°C is measured.

- Light curing -
The composition for sealing coated electric wires of the present invention preferably has a curing time of 60 seconds or less, more preferably 40 seconds or less, even more preferably 30 seconds or less, and particularly preferably 25 seconds or less, as measured by the photocurability measurement method described below.

The photocurability of the composition for sealing a coated electric wire was measured by irradiating the composition for sealing a coated electric wire with light at an illuminance of 400 mW/ ^cm2 using an LED lamp with a wavelength of 405 nm at 25°C in air, and measuring the time until the composition for sealing a coated electric wire was cured.

<How to use>
The composition for sealing coated electric wires of the present invention can be used for various coated electric wires, such as a single conductor coated with an insulating coating, or a stranded wire made of several conductors twisted together and coated with an insulating coating.
Specifically, the exposed portion of the insulated electric wire and its surroundings are covered with the composition of the present invention, and the composition of the present invention is cured, thereby making it possible to seal the surroundings of the exposed portion of the insulated electric wire.
As the coating method, various methods can be used, for example, a method of applying or injecting the composition of the present invention onto the exposed portion of the coated electric wire and its surroundings, or a method of immersing the exposed portion of the coated electric wire and its surroundings in the composition of the present invention.
The coated composition of the present invention can be cured by any method commonly used for cyanoacrylate adhesives. Generally, the composition will cure due to moisture in the air when left to stand. If the curing speed of the composition is insufficient, the curing can be accelerated by spraying the coated portion with an amine anionic polymerization initiator, such as N,N'-dimethylaniline, triethanolamine, N,N'-diethyl-m-toluidine, or N,N'-dimethyl-p-toluidine (commercially available products include aa Accelerator (manufactured by Toagosei Co., Ltd.)).
Of the compositions of the present invention, low-viscosity compositions are preferred because they can easily penetrate into the gap between the conductor and the coating, adequately seal the coated electric wire, and also have excellent workability. It is preferable to employ a method in which the exposed portion of the coated electric wire and its surroundings are immersed in the composition of the present invention.
More specifically, a conductor from which the coating of a coated electric wire has been stripped is crimped to a specific part, and the exposed portion of the coated electric wire and its surroundings are immersed in the composition of the present invention. The time for which the exposed portion of the coated electric wire and its surroundings are immersed may be appropriately selected depending on the type of composition used, but is usually several seconds to about 30 seconds.
In this method, if the curing rate is too fast and the composition does not sufficiently penetrate into the gap between the conductor and the coating, a composition containing an increased amount of the polymerization inhibitor may be used.

(Coated wire)
The covered electric wire of the present invention comprises a cured product of the composition for sealing a covered electric wire of the present invention.
The composition for sealing a coated electric wire of the present invention can be suitably used for sealing a portion of a coated electric wire, particularly an end of the coated electric wire, where the electric wire is exposed, and can be more suitably used for sealing an exposed portion of an electric wire where two or more coated electric wires are electrically connected.
The exposed portion of the electric wire may be an end portion or an intermediate portion of the insulated electric wire.
The composition for sealing a covered electric wire of the present invention can also be suitably used for sealing a connection portion between a covered electric wire and another member (such as a connector, a terminal, a protector, a former, a fixture, or a substrate).

The electric wire in the coated electric wire is not particularly limited, and a known electric wire can be used. Examples of the material of the electric wire include copper, aluminum, and alloys thereof.
The electric wire may be a single wire or a multi-strand wire, but is preferably a multi-strand wire.
The covering material for the covered electric wire is not particularly limited, and any known covering material can be used.
The covering material is preferably an insulating material.
The covering material preferably contains a resin, and more preferably contains a thermoplastic resin.
The cross-sectional shape, length, thickness of the coating, etc. of the coated electric wire are not particularly limited and may be appropriately selected.
Suitable examples of the coated electric wire of the present invention include wire harnesses for automobiles, home electric appliances, office automation equipment, and the like, and particularly suitable examples include wire harnesses for automobiles.

The present invention will be specifically described below based on examples. Note that the present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

<Method for measuring viscosity at 25° C.>
The viscosity at 25°C was measured in accordance with the measurement method using a rotational viscometer specified in JIS Z 8803 (2011).

(Examples 1 to 17 and Comparative Examples 1 to 10)
In Examples 1 to 17 and Comparative Examples 1 to 10, compositions for sealing coated electric wires were prepared by mixing the compounds shown in Tables 1 to 3 in a conventional manner, except that Examples 1, 2, 4, 12, 14, 16, and 17 are reference examples.

<Evaluation>
The obtained compositions for sealing coated electric wires were evaluated as follows. The results are shown in Table 2.

-Method of measuring curing time-
In order to confirm the performance regarding workability, the composition for sealing a coated electric wire applied to an electric wire was irradiated with light at an illuminance of 400 mW/ ^cm2 using an LED lamp having a wavelength of 405 nm, and the time until the composition for sealing a coated electric wire was cured was measured.

- Wire sealing test (initial test, heat resistance test, and thermal shock test) -
In order to confirm the performance as a sealing material (sealing material) for covered electric wires, it was confirmed whether the sealing material molded around the electric wires had sufficient sealing properties.
The covering material was removed, and the exposed metal conductor portions of the bundled electric wire were exposed. The sealing material (composition for sealing covered electric wires) that molded the metal conductor portions was irradiated with light. The molding material hardened in the electric wire. The electric wire was then cured at room temperature for 5 days to obtain electric wire 1.
The following three types of tests were performed using two types of electric wires, each having a conductor wire number/wire diameter/outer diameter of 41 wires/0.32 mm/2.4 mm and 58 wires/0.26 mm/2.3 mm, respectively.

<<Initial>>
After sealing, 30 kPa of air was blown into the "electric wire 1" from the end portion of the electric wire in the direction of the molding at room temperature (25°C, same below), and it was confirmed whether the sealing material had sealed by checking whether air leaked out.

<<After heat resistance test>>
After the sealing, the "electric wire 1" was left in a room temperature dryer at 120°C for 120 hours, and then 30 kPa of air was blown in from the end of the electric wire in the direction of the molding at room temperature, and it was confirmed whether the sealing material had sealed by checking whether air leaked out.

<<After thermal shock test>>
Using a thermal shock tester, the sample was left in a -40°C environment for 1 hour and then in a 125°C environment for 1 hour, which constituted one cycle. The sealed "electric wire 1" was left for 100 cycles, and then 30 kPa of air was blown in from the end of the electric wire in the direction of the molding at room temperature, and it was confirmed whether or not the sealing material had sealed by checking whether or not air leaked.

The three types of tests were performed on two types of "wire 1" made from the same composition for sealing coated electric wires. Samples of both types that showed no leaks even when air was blown into them were given an A, samples that showed no air leaks in one type of wire but leaks were confirmed in the other were given a B, samples that showed air leaks in both types of wire were given a C, and samples that did not harden when exposed to light and therefore could not be evaluated were given a -.

Details of the abbreviations in Table 1 are shown below.
<Acrylic isocyanate compound>
Laromer PR-9000: Acrylic isocyanate manufactured by BASF Corporation Ebicryl 4396: Acrylic isocyanate manufactured by Daicel Allnex Co., Ltd. <Isocyanate compound>
Sumijule E21-2: Diphenylmethane diisocyanate modified polyisocyanate manufactured by Sumika Covestro Urethane Co., Ltd. SBU0620: Diphenylmethane diisocyanate modified polyisocyanate manufactured by Sumika Covestro Urethane Co., Ltd. Duranate E402-100: Adduct type hexamethylene diisocyanate modified polyisocyanate manufactured by Asahi Kasei Corporation Duranate WT31-100: Water-dispersible hexamethylene diisocyanate modified polyisocyanate manufactured by Asahi Kasei Corporation ((meth)acrylate monomer)
Viscoat 190: Ethyl carbitol acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd. DMAA: Dimethylacrylamide manufactured by KJ Chemicals Co., Ltd. ACMO: Acryloylmorpholine manufactured by KJ Chemicals Co., Ltd. Kayarad HX-620: Diacrylate monomer manufactured by Nippon Kayaku Co., Ltd. Light Ester P-2M: Bis(2-methacryloxyethyl) acid phosphate manufactured by Kyoeisha Chemical Co., Ltd. <Moisture curing catalyst>
U-CAT 660M: morpholine-based urethane catalyst (photopolymerization initiator) manufactured by San-Apro Co., Ltd.
Omnirad 369: α-aminoacetophenone-based photopolymerization initiator manufactured by IGM Resins Omnirad 1173: α-hydroxyketone-based photopolymerization initiator manufactured by IGM Resins Omnirad TPO: acylphosphine oxide-based photopolymerization initiator manufactured by IGM Resins <Anaerobic curing catalyst>
Percumyl H-80: cumene hydroperoxide manufactured by NOF Corp. Saccharin: 2-sulfobenzoic acid imide

As shown in Tables 1 to 3, the compositions for sealing covered electric wires of Examples 1 to 17 provided excellent heat resistance of the resulting electric wire seals for covered electric wires, as compared with the compositions of Comparative Examples 1 to 10.
Furthermore, as shown in Tables 1 and 2, the compositions for sealing covered electric wires of Examples 1 to 17 also provided the resulting wire seals for covered electric wires with excellent resistance to cold and heat shocks.

The coated electric wire sealing composition of the present invention has excellent workability, and the cured product can maintain its electric wire sealing properties even under severe conditions such as high temperatures, so it can be widely used as an electric wire sealant for wiring in various electrical systems such as automobiles, home appliances, and office equipment.

The disclosure of Japanese Patent Application No. 2020-127713, filed on July 28, 2020, is incorporated herein by reference in its entirety.
All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.

Claims (11)

As the component (A), a compound having an isocyanate group,
As the component (B), a compound having a (meth)acrylic group, and
The composition contains a photopolymerization initiator as the component (C),
The component (B) contains a compound having two or more (meth)acryl groups,
the content of the compound having two or more (meth)acrylic groups is 0.1% by mass to 40% by mass relative to the total mass of the composition ,
A composition for sealing a coated electric wire, wherein the content of the component (A) is more than 50 mass % based on the total mass of the composition. The coated electric wire sealing composition according to claim 1, wherein the component (A) includes an isocyanate prepolymer. The composition for sealing coated electric wires according to claim 1 or 2, wherein the component (A) contains a compound in which an isocyanate group is directly bonded to an aromatic ring. The composition for sealing coated electric wires according to any one of claims 1 to 3, wherein the composition contains a moisture curing catalyst. The composition for sealing coated electric wires according to any one of claims 1 to 4, wherein the content of the component (A) is 60 mass% or more based on the total mass of the composition. The composition for sealing coated electric wires according to any one of claims 1 to 5, wherein the content of the component (B) is 15 mass% or more based on the total mass of the composition. The composition for sealing coated electric wires according to any one of claims 1 to 6, wherein the component (A) includes a compound having an isocyanate group and a (meth)acrylic group. The composition for sealing coated electric wires according to claim 7, wherein the content of the compound having an isocyanate group and a (meth)acrylic group is 5% by mass or more based on the total mass of the composition. As the component (A'), a compound having an isocyanate group and a (meth)acrylic group;
The composition contains, as the component (B), a compound other than the component (A') that has a (meth)acrylic group, and as the component (C), a photopolymerization initiator,
The component (B) contains two or more compounds having two or more (meth)acryl groups,
the content of the compound having two or more (meth)acrylic groups is 0.1% by mass to 40% by mass relative to the total mass of the composition ,
The composition for sealing a coated electric wire, wherein the content of the component (A') is 25 mass % or more based on the total mass of the composition. The composition for sealing coated electric wires according to claim 9, wherein the composition contains a moisture curing catalyst. A coated electric wire comprising a cured product of the composition for coated electric wire sealing according to any one of claims 1 to 10.