JP7370816B2 - Coating material, resin coating structure using the same, and electric wire with terminal - Google Patents

Description

The present invention relates to a coating material used, for example, for corrosion protection of automobile parts, a resin coating structure using the same, an electric wire with a terminal, and the like.

Conventionally, electric wires made of copper-based materials with excellent electrical conductivity have been used as power lines and signal lines in fields such as automobiles, OA equipment, and home appliances. In particular, in the automobile field, the performance and functionality of vehicles are rapidly increasing, and the number of various electrical devices and control devices mounted on vehicles is increasing. Therefore, along with this, there is a tendency for the number of electric wires with terminals to be used to increase.

On the other hand, with environmental issues attracting attention, there is a demand for lighter automobiles. Therefore, an increase in weight due to an increase in the amount of wire harness used becomes a problem. For this reason, lightweight aluminum electric wires are attracting attention in place of conventionally used copper wires.

Here, connection terminals are used when connecting such electric wires to each other or at connection parts of devices and the like. However, even in the case of an electric wire with a terminal using an aluminum electric wire, copper, which has excellent electrical properties, is sometimes used for the terminal part in order to ensure the reliability of the connection part. In such cases, aluminum wires and copper terminals are used together.

However, when dissimilar metals are brought into contact, so-called electrolytic corrosion may occur due to the difference in standard electrode potential. In particular, since the standard electrode potential difference between aluminum and copper is large, corrosion on the electrically base aluminum side progresses due to the influence of water splashing and dew condensation on the contact portion. As a result, the connection between the wire and the terminal at the connection point becomes unstable, increasing contact resistance, increasing electrical resistance due to a decrease in wire diameter, and even breaking the wire, which may lead to malfunction or stoppage of electrical components. be.

For this reason, a method has been proposed in which the connection portion between the electric wire and the terminal is covered with a resin member. At this time, it is possible to ensure that the applied coating material penetrates deep into the coated wire and harden it to form a coating layer, as well as improve the interfacial adhesion strength between the aluminum wire and copper terminal and the coating layer. Desired.

Such resin materials include, for example, ultraviolet curable materials containing an ultraviolet curable material and a chain transfer agent consisting of a compound containing at least one selected from urethane bonds, urea bonds, and isocyanate groups, and metal-containing compounds. A composition has been proposed (Patent Document 1).

Japanese Patent Application Publication No. 2012-251034

On the other hand, as described above, electric wires with terminals for automobiles are used in various environments. Therefore, in order to improve the interfacial adhesive strength between the aluminum electric wire or copper terminal and the coating layer, a method of adding a silane coupling agent to a coating material containing an ultraviolet curable resin may be adopted. By adding a silane coupling agent, it reacts or interacts with the aluminum electric wire and the copper terminal through a hydrolysis reaction and a dehydration condensation reaction, thereby improving the interfacial adhesive strength between the coating material and the metal.

Here, it is known that the reaction rate of the hydrolysis reaction and dehydration condensation reaction of a silane coupling agent generally increases in an acidic or basic environment. Therefore, in order to promote the reaction of the silane coupling agent and further improve the interfacial adhesive strength, it is possible to make the resin composition used as the coating material acidic or basic.

However, when the resin composition is made acidic or basic, the viscosity becomes extremely high, making it difficult to get the resin into small gaps. For this reason, when applied to an electric wire with a terminal in which an aluminum electric wire and a copper terminal are crimped together as described above, the coating material does not penetrate into the gap and a gap is created, which may become a path for water to infiltrate.

Furthermore, if the resin composition is made acidic or basic, the reaction of the silane coupling agent will naturally proceed during storage, and the resin composition will become cloudy. That is, in the method of making the resin composition acidic or basic, there is a problem that the resin composition is difficult to handle.

The present invention has been made in view of the above-mentioned problems, and includes, for example, a coating material that can improve the interfacial adhesive strength with aluminum electric wires, copper terminals, etc., and can also be easily filled into gaps. The object of the present invention is to provide a resin coating structure and a terminal-equipped electric wire using the same.

In order to achieve the above-mentioned object, the first invention is a coating material applied to a member to be coated, which comprises an ultraviolet curable resin containing a photopolymerization initiator that generates radicals when irradiated with light in the ultraviolet region. , a silane coupling agent, and a photoacid generator that generates an acid by irradiation with light in the ultraviolet region , the photoacid generator is an onium salt-based photoacid generator, and the anion is A coating material containing at least one of a borate anion and a gallate anion .

According to the first invention, since a photoacid generator that generates an acid when irradiated with light is added to the coating material, irradiation with light can cause the hydrolysis reaction and dehydration condensation reaction of the silane coupling agent. The reaction rate can be increased. Therefore, during application, the coating material can penetrate even into minute gaps due to its low viscosity, and by irradiating it with light, the interfacial adhesive strength due to the silane coupling agent can be improved.

Further, the coating material includes an ultraviolet curing resin containing a photopolymerization initiator that generates radicals when irradiated with light. Therefore, by irradiating ultraviolet rays, the ultraviolet curable resin can be cured, and at the same time, acid can be generated by the photoacid generator, and the reaction of the silane coupling agent can be accelerated. Therefore, the process does not become complicated. Furthermore, since almost no acid is generated from the photoacid generator in the absence of light irradiation, clouding during storage can be suppressed, and the coating material can be easily handled.

Furthermore, when the photoacid generator is an onium salt-based photoacid generator and the anion includes either a borate anion or a gallate anion, discoloration of the metal after light irradiation can be suppressed.

A second invention is a resin coating structure characterized in that the coating material according to the first invention is applied to a member to be coated and cured.

According to the second aspect of the invention, it is possible to cure the resin film to a deep part in a short time, and it is possible to obtain a resin film structure with high interfacial adhesive strength.

A third invention is the resin coating structure according to the second invention, in which the member to be covered is an electric wire with a terminal in which a covered conductor wire and a terminal are connected, and the covered conductor wire has a covering portion and a terminal. the terminal has a terminal main body and a crimping part, the crimping part includes a conductor crimping part to which the conducting wire is crimped, and a covering crimping part to which the covering part is crimped. and an inter-barrel portion between the conductor crimping portion and the covering crimping portion, wherein at least a portion where the conductor is exposed from the inter-barrel portion to the conductor crimping portion is hardened with the coating. It is an electric wire with a terminal characterized by being covered with material.

According to the third invention, it is possible to obtain an electric wire with a terminal in which the coating material is applied to the lower part of the conductive wire and is cured.

According to the present invention, there is provided a coating material that can improve the interfacial adhesion strength with, for example, aluminum electric wires and copper terminals, and that can be easily filled into gaps, and a resin coating structure using the same. Electric wires with terminals can be provided.

FIG. 1 is a perspective view showing an electric wire 10 with a terminal. FIG. 1 is a cross-sectional view showing an electric wire 10 with a terminal. The figure which shows the terminal 1 and the covered conductor 11 before crimping. (a) is a diagram showing the process of applying the coating material 17a to the electric wire 10 with a terminal, and (b) is a cross-sectional view showing the process of curing the coating material 17a. A diagram showing a resin coating structure 20. (a), (b) is a figure which shows the method of measuring the interfacial adhesive strength of the coating material 17a.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an electric wire 10 with a terminal, and FIG. 2 is a sectional view. Note that FIG. 1 is a perspective view of the coating layer 17. The electric wire 10 with a terminal is configured by connecting a terminal 1 and a covered conductive wire 11.

The covered conductive wire 11 includes a conductive wire 13 made of aluminum or an aluminum alloy, and a covering portion 15 that covers the conductive wire 13. That is, the covered conductive wire 11 includes a covered portion 15 and a conductive wire 13 exposed from the tip thereof. The conducting wire 13 is, for example, a stranded wire in which a plurality of wires are twisted together.

The terminal 1 is of an open barrel type and made of copper or copper alloy. A covered conductor wire 11 is connected to the terminal 1 . The terminal 1 is constructed by connecting a terminal body 3 and a crimp section 5 via a transition section 4 . The transition portion 4 located between the crimp portion 5 and the terminal body 3 is open at the top.

The terminal main body 3 is formed from a plate-like material having a predetermined shape into a cylindrical body having a rectangular cross section. The terminal main body 3 has an elastic contact piece formed by folding a plate-like material into a rectangular cylinder. A male terminal or the like is inserted into the terminal body 3 from the front end and connected thereto. In the following description, an example will be shown in which the terminal main body 3 is a female terminal that allows insertion of an insertion tab (not shown) such as a male terminal, but in the present invention, the detailed shape of the terminal main body 3 is not particularly limited. For example, instead of the female terminal main body 3, an insertion tab for a male terminal may be provided.

The crimping portion 5 is a portion that is crimped to the covered conductive wire 11, and before crimping, the cross section perpendicular to the longitudinal direction of the terminal 1 has a substantially U-shaped barrel shape. The crimping part 5 of the terminal 1 includes a conductor crimping part 7 for crimping the conductor 13 exposed from the sheathing part 15 on the distal end side of the sheathed conductor 11 , a covering crimping part 9 for crimping the sheathing part 15 of the sheathed conductor 11 , and a conductor crimping part 9 for crimping the sheathing part 15 of the sheathed conductor 11 . It consists of an inter-barrel section 8 between the section 7 and the covering crimp section 9.

A portion of the inner surface of the conductive wire crimping portion 7 is provided with serrations (not shown) in the width direction (direction perpendicular to the longitudinal direction). By forming the serrations in this manner, when the conducting wire 13 is crimped, the oxide film on the surface of the conducting wire 13 is easily destroyed, and the contact area with the conducting wire 13 can be increased.

The covering portion 15 is peeled off from the tip of the covered conductive wire 11, and the internal conductive wire 13 is exposed. The covering portion 15 of the covered conducting wire 11 is crimped by the covering crimping portion 9 of the terminal 1 . Further, the conducting wire 13 exposed by peeling off the covering portion 15 is crimped by the conducting wire crimping portion 7 . In the conductor crimping section 7, the conductor 13 and the terminal 1 are electrically connected. Note that the end surface of the covering portion 15 is located in the inter-barrel portion 8 between the covering crimping portion 9 and the conductor crimping portion 7.

In the present invention, at least the portion where the conducting wire 13 is exposed from the inter-barrel portion 8 to the conducting wire crimping portion 7 is covered with the coating layer 17. That is, the conductive wire 13 is not exposed to the outside due to the covering layer 17. The coating layer 17 functions as an anti-corrosion layer, and constitutes a resin coating structure by applying a coating material to be described later to the electric wire with a terminal, which is the member to be coated, and curing the coating material.

Next, the coating material constituting the coating layer 17 will be explained. A coating material applied to a member to be coated, such as an electric wire with a terminal, includes at least an ultraviolet curing resin, a silane coupling agent, and a photoacid generator.

The ultraviolet curable resin has, for example, at least two ethylenically unsaturated groups that are polymerized and cured by ultraviolet rays, and is preferably an oligomer. In addition, an oligomer here is a polymer with a polymerization degree of 2 or more and 100 or less. Further, the ultraviolet curable resin contains a photopolymerization initiator that generates radicals when irradiated with light in the ultraviolet region.

In addition, the coating material includes a silane coupling agent that interacts through hydrolysis and dehydration condensation, and a photoacid generator that generates acids such as Lewis acid and Brønsted acid when irradiated with light in the ultraviolet region. . Hydrolysis and dehydration condensation of the silane coupling agent are promoted by the acid generated from the photoacid generator, and the adhesive strength between the resin contained in the coating layer 17 and the conductive wire made of aluminum or aluminum alloy and the copper terminal is increased. will improve.

[Photoacid generator]
The photoacid generator generates acid by absorbing irradiated light and then decomposing to extract hydrogen from the solvent or from the photoacid generator itself. Although the light absorbed by the photoacid generator differs depending on the type of photoacid generator, it is, for example, ultraviolet light in a wavelength range of approximately 200 nm or more and 405 nm or less. Note that the wavelength range of the light that cures the ultraviolet curable resin contained in the coating material constituting the coating layer 17 and the wavelength range of the light that causes the photoacid generator to generate acid may at least partially overlap. desirable. Thereby, the curing of the ultraviolet curable resin and the generation of acid by the photoacid generator can be performed simultaneously by light from one type of light source.

Photoacid generators can be broadly classified into onium salt photoacid generators and nonionic photoacid generators. In this embodiment, at least one of an onium salt-based photoacid generator and a nonionic photoacid generator is used, but other types of photoacid generators may also be used. The onium salt-based photoacid generator that can be used in the coating material of the coating layer 17 is not particularly limited, but includes, for example, organic sulfonium salt compounds, organic oxonium salt compounds, organic ammonium salt compounds, organic phosphonium salt compounds, and organic iodonium salt compounds. Examples include those having a counter anion such as hexafluoroantimonate anion, tetrafluoroborate anion, hexafluorophosphate anion, hexachloroantimonate anion, trifluoromethanesulfonate ion, or fluorosulfonate ion. Specific chemical formulas of the counter anions include, for example, anions represented by B(C ₆ F ₅ ) ₄ ^- , SbF ₆ ^{- ,} SbF ₄ -, AsF ₆ ^- , PF ₆ ^- , BF ₄ ^- , CF ₃ SO ₃ ^-. It is. These may be used alone or in combination of two or more.

Commercially available onium salt photoacid generators include, for example, IRGACURE (registered trademark, hereinafter omitted) 250, IRGACURE 270, IRGACURE 290 (trade name, manufactured by BASF), WPI-113, WPI-116, WPI-169, WPI-170, WPI-124, WPAG-638, WPAG-469, WPAG-370, WPAG-367, WPAG-336 (trade names, manufactured by Wako Pure Chemical Industries, Ltd.), B2380, B2381, C1390, D2238, D2248, D2253, I0591, T1608, T1609, T2041, T2042 (manufactured by Tokyo Chemical Industry Co., Ltd., product name), AT-6992, At-6976 (manufactured by ACETO, product name), CPI-100, CPI -100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-310FG, IK-1, IK-2 (product names manufactured by Sun-Apro Co., Ltd.), SP-056, SP-066, SP-130, SP-140, SP-150, SP-170, SP-171, SP-172 (all manufactured by ADEKA Corporation, product names), CD-1010, CD-1011, CD-1012 (all manufactured by Sartomer) (manufactured by Rhodia Japan, trade name), and PI2074 (manufactured by Rhodia Japan, trade name).

Nonionic photoacid generators that can be used in the coating material constituting the coating layer 17 are not particularly limited, but include, for example, phenacylsulfone type photoacid generators, o-nitrobenzyl ester type photoacid generators, and iminosulfonates. Examples include photoacid generators of the sulfonic acid ester type of N-hydroxyimide, and photoacid generators of the sulfonic acid ester type of N-hydroxyimide. These may be used alone or in combination of two or more. Specific compounds of the nonionic photoacid generator include, for example, sulfonyldiazomethane, oxime sulfonate, imidosulfonate, 2-nitrobenzylsulfonate, disulfone, pyrogallolsulfonate, p-nitrobenzyl-9,10-dimethoxyanthracene-2- Sulfonate, N-sulfonyl-phenylsulfonamide, trifluoromethanesulfonic acid-1,8-naphthalimide, nonafluorobutanesulfonic acid-1,8-naphthalimide, perfluorooctanesulfonic acid-1,8-naphthalimide, pentafluoro Benzenesulfonic acid-1,8-naphthalimide, nonafluorobutanesulfonic acid-1,3,6-trioxo-3,6-dihydro-1H-11-thia-azacyclopentaanthracen-2-yl ester, nonafluorobutane Sulfonic acid-8-isopropyl-1,3,6-trioxo-3,6-dihydro-1H-11-thia-2-azacyclopentaanthracen-2-yl ester, 1,2-naphthoquinone-2-diazide-5 -Sulfonic acid chloride, 1,2-naphthoquinone-2-diazido-4-sulfonic acid chloride, 1,2-benzoquinone-2-diazido-4-sulfonic acid chloride, 1,2-naphthoquinone-2-diazide-5-sulfone sodium acid, sodium 1,2-naphthoquinone-2-diazide-4-sulfonate, sodium 1,2-benzoquinone-2-diazide-4-sulfonate, potassium 1,2-naphthoquinone-2-diazide-5-sulfonate , potassium 1,2-naphthoquinone-2-diazido-4-sulfonate, potassium 1,2-benzoquinone-2-diazido-4-sulfonate, methyl 1,2-naphthoquinone-2-diazido-5-sulfonate, 1 , methyl 2-benzoquinone-2-diazide-4-sulfonate, and the like.

Commercially available nonionic photoacid generators include, for example, WPAG-145, WPAG-149, WPAG-170, WPAG-199 (trade names, manufactured by Wako Pure Chemical Industries, Ltd.), D2963, F0362, M1209, M1245 (trade name manufactured by Tokyo Kasei Kogyo Co., Ltd.), SP-082, SP-103, SP-601, SP-606 (trade name manufactured by ADEKA Co., Ltd.), SIN-11 (trade name manufactured by Sanpo Chemical Co., Ltd.) Examples include NT-1TF (manufactured by San-Apro Co., Ltd., trade name), and NT-1TF (manufactured by San-Apro Co., Ltd., trade name).

The amount of the photoacid generator added is 0.01 wt% or more, preferably 0.1 wt% or more of the entire coating material constituting the coating layer 17. When the amount of photoacid generator is less than this, the progress rate of the hydrolysis reaction and dehydration condensation reaction of the silane coupling agent decreases due to the small amount of acid generated from the photoacid generator, and the coating material and aluminum It takes time to develop adhesion between the electric wire and the copper terminal. Note that "wt%" indicates mass percent concentration (the same applies hereinafter).

Further, it is desirable that the amount of the photoacid generator added is equal to or less than the amount of the photopolymerization initiator contained in the coating material constituting the coating layer 17. The amount of photopolymerization initiator contained in When adding more photoacid generator than photopolymerization initiator, it inhibits the reaction of the photopolymerization initiator, which also absorbs ultraviolet rays and generates radical species, resulting in a decrease in the curability of the coating material and a decrease in elasticity. rate may decrease. Specifically, the amount of the photoacid generator added is preferably 10 wt% or less, preferably 5 wt% or less, and more preferably 3 wt% or less, based on the entire coating material.

[Silane coupling agent]
As the silane coupling agent, any silane coupling agent can be used, including known and publicly available ones, as long as it does not interfere with the effects of the present invention. The amount of the silane coupling agent added is appropriately determined by experiments and the like. Specific compounds of the silane coupling agent are not particularly limited, but for example, tetramethylsilicate, tetraethylsilicate, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Trimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxy Silane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N- 2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- Triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3 Examples include -mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane.

The amount of the silane coupling agent added is preferably 0.1 wt% or more and 10 wt% or less, more preferably 0.5 wt% or more and 5.0 wt% or less, based on the entire coating material constituting the coating layer 17. Within the above range, the adhesive strength between the aluminum wire and the copper terminal and the coating material will be sufficient, and the coating material will have excellent storage stability.

Further, the coating material constituting the coating layer 17 may contain a diluent monomer, a photosensitizer, a photopolymerization initiator, a chain transfer agent, and various additives. As the diluent monomer, monofunctional (meth)acrylate or polyfunctional (meth)acrylate is used. For example, glycidyl (meth)acrylate is used. The diluent monomer is a monomer for diluting the ultraviolet curing resin.

[Photopolymerization initiator]
The photopolymerization initiator absorbs light in the wavelength range emitted from the ultraviolet irradiation device and generates radicals, thereby causing the ultraviolet curable resin to initiate polymerization. The amount of the photopolymerization initiator added is appropriately determined by experiments and the like. The photopolymerization initiator is not particularly limited, but for example, an acylphosphine oxide photopolymerization initiator, an acetophenone photopolymerization initiator, an o-acyloxime photopolymerization initiator, etc. can be used.

[Photosensitizer]
A photosensitizer is added to the coating material for the purpose of improving the photosensitivity of the photoacid generator. A photosensitizer improves the photosensitivity of a photoacid generator by absorbing light in a wavelength range that cannot be absorbed by the photoacid generator. Therefore, the absorption wavelength range of the photosensitizer and the absorption wavelength range of the photoacid generator are different, and it is preferable that there is less overlap between them.

The amount of the photosensitizer added is preferably 0.1 wt% or more and 10 wt% or less, more preferably 0.5 wt% or more and 10 wt% or less, based on the entire coating material constituting the coating layer 17. . When the photosensitizer content is 0.1 wt% or more, it is easy to obtain the desired sensitivity, and when it is 10 wt% or less, it is easy to ensure the transparency of the coating.

Examples of the photosensitizer that can be used in the coating material constituting the coating layer 17 include, but are not limited to, anthracene derivatives, benzophenone derivatives, thioxanthone derivatives, anthraquinone derivatives, benzoin derivatives, and the like. More specifically, as a photosensitizer, 9,10-dialkoxyanthracene, 2-alkylthioxanthone, 2,4-dialkylthioxanthone, 2-alkylanthraquinone, 2,4-dialkylanthraquinone, p,p'-aminobenzophenone, Examples include 2-hydroxy-4-alkoxybenzophenone and benzoin ether.

Specific compounds of the photosensitizer include, but are not particularly limited to, anthrone, anthracene, 9,10-diphenylanthracene, 9-ethoxyanthracene, pyrene, perylene, coronene, phenanthrene, benzophenone, benzyl, benzoin, 2- Methyl benzoylbenzoate, butyl 2-benzoylbenzoate, benzoin ethyl ether, benzoin-i-butyl ether, 9-fluorenone, acetophenone, p,p'-tetramethyldiaminobenzophenone, p,p'-tetraethylaminobenzophenone, 2-chloro Thioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, phenothiazine, acridine orange, benzoflavin, cetoflavin-T, 2-nitrofluorene, 5-nitroacenaphthene, benzoquinone, 2-chloro-4-nitroaniline, N- Acetyl-p-nitroaniline, p-nitroaniline, N-acetyl-4-nitro-1-naphthylamine, picramide, anthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1,2-benzanthraquinone, 3-methyl -1,3-diaza-1,9-benzanthrone, dibenzalacetone, 1,2-naphthoquinone, 3,3'-carbonyl-bis(5,7-dimethoxycarbonylcoumarin), 9,10-dibutoxyanthracene , 9,10-dipropoxyanthracene and the like. These may be used alone or in combination of two or more.

In addition, the coating material constituting the coating layer 17 may contain a colorant or dye. As coloring pigments and dyes, cyanine compounds, phthalocyanine compounds, naphthoquinone compounds, diimmonium compounds, naphthalocyanine compounds, squalium dyes, quinone compounds, azo compounds, quinacridone, dioxane, bensimidazolone, carbon black, titanium oxide, etc. may be used. I can do it. These components may be used alone or in combination of two or more.

Next, a method for manufacturing the electric wire 10 with a terminal will be described. First, as shown in FIG. 3, the terminal 1 and the covered conductive wire 11 are prepared by peeling off the tip of the covering portion 15 to expose the conductive wire 13.

Next, the conducting wire 13 of the covered conducting wire 11 is placed in the conducting wire crimping section 7 , and the covering section 15 is placed in the covering crimping section 9 . At this time, the tip of the covering part 15 is located in the inter-barrel part 8. Next, the conducting wire 13 is crimped by the conducting wire crimping part 7, and the covering part 15 is crimped by the covering crimping part 9, and the covered conducting wire 11 and the terminal 1 are connected by crimping.

Next, as shown in FIG. 4(a), the above-mentioned coating material 17a is applied using, for example, a dispenser 19 to at least the area where the conductor 13 is exposed from the inter-barrel portion 8 to the conductor crimping portion 7. Thereafter, as shown in FIG. 4B, the coating material 17a is cured by irradiating ultraviolet rays from the light source 21 to form the coating layer 17. Through the above process, it is possible to obtain the terminal-equipped electric wire 10 in which the exposed portion of the conductive wire 13 is covered with the coating layer 17 formed by curing the coating material 17a.

As explained above, according to the present embodiment, the coating material 17a used when forming the coating layer 17 contains a photopolymerization initiator that generates radicals when irradiated with light in the ultraviolet region, and a photopolymerization initiator that generates an acid. Contains a photoacid generator and a silane coupling agent. Therefore, when ultraviolet irradiation is performed, the generated radicals can reliably harden the coating material 17a and at the same time generate acid. Therefore, the generated acid accelerates the progress of the hydrolysis reaction and dehydration condensation reaction of the silane coupling agent, and immediately after UV curing, high adhesion between the aluminum electric wire and the copper terminal and the coating layer 17 is obtained, resulting in corrosion protection. It is possible to obtain a coating structure with excellent water resistance and waterproof properties.

Furthermore, the photoacid generator generates acid only after being irradiated with ultraviolet rays. Therefore, in the state before irradiation with ultraviolet rays, the coating material 17a is not acidic, so the viscosity of the coating material 17a is low. Therefore, the coating material 17a can be reliably penetrated into the narrow gap between the electric wires with terminals, and the gap between the terminal and the electric wire can be filled with the coating material 17a.

Furthermore, since the photoacid generator hardly generates acid in a dark place, the coating material 17a is prevented from becoming acidic during storage. For example, in a configuration in which the coating material is made acidic in advance in order to promote the reaction of the silane coupling agent, there is a problem that the reaction of the silane coupling agent naturally proceeds during storage. On the other hand, the coating material 17a according to the present embodiment has good storage stability since almost no acid is generated from the photoacid generator when stored in a dark place.

In this embodiment, the member to be coated is the electric wire 10 with a terminal to which the covered conductor 11 and the terminal 1 are connected, and the coating material 17a is applied to the electric wire 10 with a terminal, which is the member to be coated, and hardened. Although an example has been described, the present invention is not limited to this example.

For example, FIG. 5 is a diagram (perspective view of the coating layer 17) showing a resin coating structure 20 in which a coating layer 17 is formed at a connection portion where a plurality of covered conductive wires 11 are connected. In this case, a plurality of coated conductive wires 11 are connected to each other by, for example, welding, and the coating material 17a is applied to the exposed portion of the conductive wire 13, and then ultraviolet rays are irradiated to achieve excellent interfacial adhesion strength with the conductive wire 13. A covering layer 17 can be formed. At this time, since the viscosity of the coating material is low before irradiation with ultraviolet rays, the coating material 17a can also penetrate into the gaps between the conducting wires 13.

As described above, any resin coating structure that requires coating the coating material 17a on the member to be coated and curing it to form the coating layer 17 for corrosion prevention or protection can be used in any field. For example, any process in which resin is applied to a member to be coated, such as an optical fiber coating process, a resin coating process for electronic components or optical pickups, a print resist curing process, a resin coating process when bonding various parts, etc. It can also be used in the field.

Next, various evaluations were performed using a plurality of coating materials, which will be described below. As mentioned above, the coating material subjected to evaluation consists of an ultraviolet curing resin containing a photopolymerization initiator, a photoacid generator, and a silane coupling agent.

A UV-curable polyether urethane acrylate resin was used as the UV-curable resin for the coating material. The Young's modulus was adjusted to 80 MPa by changing the molecular weight of the polyether portion in the oligomer, and the types and amounts of diluent monomers and reactive monomers. As a photopolymerization initiator, Lucirin TPO (manufactured by BASF) was used, and the amount was adjusted to 2.5 wt% based on the entire coating material. Further, as a silane coupling agent, 3-acryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-5103) was used, and the amount was adjusted to 1.5 wt% based on the entire coating material.

The following was used as a photoacid generator added to the coating material.
A: Triarylsulfonium-tetrakis pentafluorophenyl gallate (manufactured by San-Apro, CPI-310FG)
B: Triarylsulfonium-tetrakis pentafluorophenylborate (manufactured by San-Apro, CPI-310B)
C: diphenyl[4-(phenylthio)phenyl]sulfonium hexafluoroantimonate (manufactured by San-Apro, CPI-101A)
D: 4-isobutylphenyl (4-methylphenyl) iodonium hexafluorophosphate (manufactured by BASF, Irgacure 250)
In each Example and Comparative Example, the type and amount of the photoacid generator added to the coating material were varied as shown in Table 1. Note that in Comparative Example 1, no silane coupling agent was added, and in Comparative Example 2, no photoacid generator was added.

(Modulus at 2.5% elongation)
The "elastic modulus at 2.5% elongation" in the table was evaluated as follows. First, a film as a sample was prepared in the following manner. Double-sided tape was pasted on a 100×100 mm glass plate, and a fluororesin sheet was pasted thereon. The coating materials according to each of the Examples and Comparative Examples were coated onto the fluororesin sheet to a thickness of 250 μm. The prepared sample was placed in a purge box to create a nitrogen atmosphere, and was irradiated with ultraviolet rays using a conveyor-type ultraviolet irradiation device with the illumination intensity and speed adjusted so that the cumulative light amount was 20 J/cm ² . The coating material thus cured was used as a film according to each example and comparative example. A 365 nm UV-LED lamp was used as the light source of the conveyor type ultraviolet irradiation device.

To determine the curability of the coating material, the tensile modulus of the film was calculated. The film according to each Example and Comparative Example was cut into strips with a width of 6 mm, and the elastic modulus of the strips at 2.5% elongation was measured in accordance with JIS K7161. The obtained elastic modulus is shown in the table as the elastic modulus at 2.5% elongation.

(Interfacial adhesive strength)
"Interfacial adhesive strength" in the table was evaluated as follows. First, as shown in FIG. 6(a), a copper ring 25 with an outer diameter of 8 mm, an inner diameter of 6 mm, and a height of 3 mm is statically placed on one end of the long side of a test piece 23 with a width of 25 mm, a length of 100 mm, and a thickness of 1 mm. After filling the inside of the copper ring 25 with the coating material 17a, it was irradiated with ultraviolet light of 20 J/cm ² (1000 mW/cm ² ×20 seconds) from a 365 nm light source 21 to be cured. The materials of the test piece 23 were aluminum, copper, and copper-tin alloy.

In the evaluation test of the interfacial adhesive strength, as shown in FIG. 6(b), a test piece 23 with a coating material adhered to one side chuck (not shown) of a tensile tester together with a splint (not shown) was used. Attach a stainless steel plate 27 with a hole 29 with an outer diameter of 9 mm on the other side, hook the copper ring 25 to the hole 29, and pull it at a speed of 100 mm/min (arrow A in the figure) to determine the cross-sectional area. The adhesive strength per unit was calculated. The test pieces 23 used in the tensile test were those as-hardened (before heat shock) and those after heat shock (+120°C to -40°C x 1000 cycles). A tensile test was conducted. Regarding the interfacial adhesive strength, those with an adhesive strength of 2.5 MPa or more after heat shock are considered to be acceptable and are indicated with an "〇" in the table, and others are rejected and indicated with an "x" in the table. Ta.

Furthermore, after each tensile test before and after the heat shock, discoloration of the test piece at the peeled portion was visually confirmed. In the table, if no discoloration was observed in any of the metal materials, it was indicated by "○", and if discoloration was observed even in some parts, it was indicated by "△".

The results show that in Examples 1 to 7 and Comparative Example 1, in which a photoinitiator and a photoacid generator were added, the elastic modulus at 2.5% elongation was approximately 80 MPa, and the photoacid generator was It was confirmed that the addition did not affect the curability of the resin.

Furthermore, in Examples 1 to 7, higher interfacial adhesive strength could be obtained for any metal than in Comparative Example 2 in which no photoacid generator was added. In particular, high interfacial adhesive strength could be maintained even after heat shock.

In addition, in Examples 1 to 4 in which the photoacid generator CPI-310B (A in the table) or CPI-310FG (B in the table) was added to the resin, discoloration and corrosion on the metal surface were not observed regardless of the amount added. There wasn't. CPI-310B (A in the table) is a borate anion with low corrosivity, and CPI-310FG (B in the table) is a gallate anion, so highly corrosive hydrogen fluoride is not produced as a by-product.

In addition, Examples 5 to 7 maintained high interfacial adhesive strength even after heat shock, but since fluoroantimonate and fluorophosphate produce hydrogen fluoride as a by-product, discoloration was observed on the metal surface after heat shock. It was done. Thus, as the photoacid generator, it is preferable to use an onium salt type photoacid generator whose anion contains at least one of a borate anion and a gallate anion.

On the other hand, in Comparative Example 2, in which no photoacid generator was added to the resin, although a certain degree of adhesive strength was obtained due to the action of the silane coupling agent, it was confirmed that the adhesive strength was lower than that in which a photoacid generator was added. It was done. That is, without the addition of a photoacid generator, the interfacial adhesive strength is insufficient, and when a load is applied after heat shock, problems such as interfacial peeling may occur.

Furthermore, it was confirmed that in Comparative Example 1, in which no silane coupling agent was added, high adhesive strength could not be obtained despite the addition of a photoacid generator. That is, it was confirmed that the effects of the above-described embodiments are exhibited by the presence of both the silane coupling agent and the photoacid generator.

In addition, in Examples 2, 4, and 6, in which the amount of the photoacid generator added was approximately the same as the amount of the photopolymerization initiator (2.5 wt%), the amount of the photoacid generator added was approximately the same as the amount of the photopolymerization initiator (2.5 wt%). The interfacial adhesive strength tended to decrease compared to Examples 1, 3, and 5 (1.5 wt %), which had a lower amount of 1.5 wt %. This may be due to the possibility that the photoacid generator inhibits the reaction of the photopolymerization initiator, which also absorbs ultraviolet rays and generates radical species. Therefore, the amount of the photoacid generator is desirably less than or equal to the amount of the photopolymerization initiator, and more desirably, the amount of the photoacid generator is less than the amount of the photopolymerization initiator.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not limited to the embodiments described above. It is clear that those skilled in the art can come up with various changes and modifications within the scope of the technical idea stated in the claims, and these naturally fall within the technical scope of the present invention. It is understood that it belongs.

1...Terminal 3...Terminal body 4...Transition section 5...Crimping section 7...Conductor crimping section 8...Inter-barrel section 9...Sheathing crimping section 10...With terminal Electric wire 11...Coated conductor wire 13...Conductor wire 15...Coating portion 17...Coating layer 17a...Coating material 19...Dispenser 20...Resin coating structure 21...Light source 23... …Test piece 25……Copper ring 27……Plate material 29……hole

Claims (3)

A coating material applied to a member to be coated,
an ultraviolet curing resin containing a photopolymerization initiator that generates radicals when irradiated with light in the ultraviolet region;
a silane coupling agent,
a photoacid generator that generates acid by irradiating it with light in the ultraviolet region;
including;
The photoacid generator is an onium salt photoacid generator, and the anion includes at least one of a borate anion and a gallate anion.
A coating material characterized by: A resin coating structure characterized in that the coating material according to claim 1 is applied to a member to be coated and cured. The resin coating structure according to claim 2 , wherein the member to be covered is an electric wire with a terminal in which a covered conductor and a terminal are connected,
The covered conducting wire includes a covering portion and a conducting wire exposed from a tip of the covering portion,
The terminal includes a terminal main body and a crimping part, and the crimping part includes a conductor crimping part to which the conductor is crimped, a covering crimping part to which the sheathing part is crimped, and the conducting wire crimping part and the covering crimping part to each other. and an inter-barrel portion between the barrels, and at least a portion where the conducting wire is exposed from the inter-barrel portion to the conducting wire crimping portion is covered with the hardened coating material. Electric wire with terminal.

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