CN1914771A - Method for waterproofing connection part of covered wire - Google Patents

Abstract

The present invention provides a method for waterproofing connection parts of covered wires which enables to surely make an electrically connected connection part of a covered wire waterproof by a simple and quick process at low cost. A method for waterproofing connection parts of covered wires is that a curing sealing material is injected into a protective cap for protecting a connection part of a covered wire, then the connection part and a covered portion near the connection part of the covered wire are put in the sealing material, and then the sealing material is cured. The sealing material is a photocuring cyanoacrylate resin composition which has a viscosity of not more than 200 mPa.s at 25 DEG in the uncured state and a tensile elongation at break of not less than 20% after curing. The sealing material is cured by irradiation of an electromagnetic wave having a wavelength capable of curing the sealing material.

Description

Waterproof treatment method for the connection part of the covered electric wire

technical field

The present invention relates to a waterproof treatment method for a connection portion of a covered electric wire, and more particularly to a waterproof treatment method for a connection portion of a covered electric wire suitable for automobile wire harnesses.

Background technique

In harnesses throughout the body of an automobile, many wire connection parts are provided for branching and connecting covered wires to each other. However, the connection processing parts of such electrically connected wire ends need to be reliably insulated from the outside and waterproof. Therefore, various wire connection methods have been proposed so far.

For example, if according to the mutual connection method of electric wires disclosed in the publication No. 63-157163, as shown in FIG. The covering of the electric wires A2 and A3 is superimposed on a pair of insulating sheets A5 of the same material to cover the above-mentioned connecting portion A4, and then the insulating sheets A5 are welded using ultrasonic waves to perform coating by adhesion. However, in the case of the connecting device between electric wires, although the above-mentioned connecting portion A4 is insulated, water often enters the insulating sheet A5 from the gap between the electric wire and the sheet or the gap between the electric wires, and the connecting portion A4 cannot be reliably waterproofed. In addition, since an ultrasonic welding machine is required, there is a problem that the cost of manufacturing equipment increases.

In addition, if the method of connecting covered electric wires disclosed in JP-A No. 1-189881 is used, as shown in FIG. A separator B8 is interposed between the pair of electric wires B6. Next, the wire B6 is inserted into the large-diameter portion B9a of the heat-shrinkable tube B9, and the connection portion B7 is inserted into the small-diameter portion B9b of the holding metal sleeve B10. Then, as shown in Figure 5(b), when the assembly is completed, the above-mentioned metal sleeve B10 is riveted, and after the above-mentioned connection part B7 is firmly fixed, the heat-shrinkable tube B9 is heated to make it shrink, and the wire B6 adhered to the The surface is sealed. However, this method of connecting covered electric wires requires many materials such as heat-shrinkable tubes, metal sleeves, and spacers, which increases the cost. In addition, not only are there many working steps, but also manufacturing equipment is required for each step, and thus the manufacturing cost increases due to equipment costs. In addition, the contact resistance between the coating and the inner surface of the tube is high, and the tip sometimes hits the end of the metal sleeve B10, so the connecting portion B7 is not easily inserted into the metal sleeve B10.

In addition, in the technology disclosed in JP-A-63-157163 and JP-1-189881, once water enters the core wire, water will further enter the coating from the gap between the core wires due to capillary phenomenon. Both have a problem of leakage of the current flowing in the electric wire.

If the method of connecting covered electric wires disclosed in JP-A-9-55278 is used, as shown in FIG. and the core wire 21b, and the coating 21a near the core wire 21b are immersed in a cyano-based adhesive, the above-mentioned cyano-based adhesive is soaked into the gap between the core wires, and then the connecting portion 25 and the core are covered with an insulating member. The wire 21b and the coating 21a in the vicinity of the core wire 21b are sealed. In the case of this method of connecting covered electric wires, the cyano-based adhesive is soaked into the gaps between the core wires and cured to prevent water from entering the coating from the gaps between the core wires. There is a problem that the cured product of the base-based adhesive is thin and easily undergoes hydrolysis due to moisture.

In addition, if the sealing method of the electric wire connection part disclosed in JP-A-11-178142 is used, as shown in FIG. While covering the heat-shrinkable tube 82 coated with the hot-melt adhesive 83 and having one end sealed with the hot-melt adhesive 83 , the heat-shrinkable tube 82 is heat-treated and sealed. The sealing method of the electric wire connecting portion is to fill the gap with a hot-melt adhesive that melts the electric wire connecting portion, then solidifies, and the electric wire connecting portion is sealed, but although the molten state occurs, the fluidity of the hot-melt adhesive is low, Therefore, it is difficult to fill the inner gap between the electric wires, and the part where the covering part has fallen off easily allows water to intrude, but there is still a problem that water resistance is not assured.

Patent Document 1: Publication No. 63-157163 of Shikaizhao

Patent Document 2: Japanese Unexamined Patent Publication No. 01-189881

Patent Document 3: Japanese Unexamined Patent Publication No. 09-055278

Patent Document 4: Japanese Unexamined Patent Publication No. 11-178142

Contents of the invention

The object of the present invention is to provide a waterproof treatment method for the connection part of the covered electric wire which improves the above-mentioned conventional problems, that is, can perform simple, rapid, low-cost and reliable waterproof treatment on the connection part of the covered electric wire which is electrically connected.

The method of waterproofing the connection part of the covered electric wire of the present invention is completed in order to solve the above-mentioned problems. After injecting a curable sealing material into the protective cap that protects the connecting part of the covered electric wire, insert the connecting part of the covered electric wire and the sealing material. In the method of waterproofing the connection portion of the covered electric wire in which the coated portion near the connecting portion of the covered electric wire is subsequently cured by curing the curable sealing material, the curable sealing material has a viscosity at 25° C. in an uncured state. A photocurable cyanoacrylate resin composition having a tensile elongation at break of 200 mPa·s or less and a cured tensile elongation of 20% or more, wherein the curing treatment is carried out by irradiating the curable sealing material It is carried out by electromagnetic waves of a wavelength that enables the curable sealing material to be cured.

In addition, in the method for waterproofing a connection portion of a covered electric wire according to the present invention, in the above-mentioned method for waterproofing a connection portion of a covered electric wire, the photocurable cyanoacrylate resin composition contains the following (A), (B ) and (C), and the tensile elongation at break of the cured product of the photocurable cyanoacrylate resin composition is greater than or equal to 20%.

(A) 2-cyanoacrylate

(B) A photopolymerizable resin component having at least one of two acryloyl groups and methacryloyl groups in the molecule

(C) Photoradical polymerization initiator

In addition, in the method of waterproofing a connection portion of a covered electric wire according to the present invention, in the above-mentioned method of waterproofing a connection portion of a covered electric wire, the protective cap is made of a material capable of transmitting the electromagnetic wave, and the electromagnetic wave of the above-mentioned wavelength passes through the protective cap. The outside of the protective cap is irradiated on the above-mentioned curable sealing material.

Using the method for waterproofing the connection part of the covered electric wire of the present invention, the connection part of the covered electric wire that is electrically connected is simple and fast, so the productivity is excellent, and the cost performance is also excellent because of the low cost, and it can be implemented reliably. Waterproof treatment.

Description of drawings

FIG. 1 is a diagram showing a connection portion of an electric wire end processed by the method of the present invention.

Fig. 2 is a perspective view showing an electric wire assembly.

Fig. 3 is a diagram showing a state in which an electric wire assembly is inserted into an insulating cap in which adhesive has entered.

FIG. 4 is a diagram showing a method of connecting electric wires disclosed in Japanese Patent Laid-Open No. 63-157163.

FIG. 5 is a diagram showing a method of connecting covered electric wires disclosed in JP-A-1-189881.

Fig. 6 is a diagram showing a method of connecting covered electric wires disclosed in JP-A-9-55278.

Fig. 7 is a diagram showing a method of connecting covered electric wires disclosed in JP-A-11-178142.

Symbol Description

60 protective cap

61 Large diameter part of protective cap

62 Small diameter part of protective cap

70 wire assembly

71 wires (covered wires)

71a Coated part

71b core wire

75 connection part

65 curable sealing material

200 Connection processing part at the end of the wire

Detailed ways

In the present invention, it is necessary to use a photocurable cyanoacrylate resin composition as the curable sealing material. That is, by using a photocurable curable sealing material, it is possible to quickly and reliably cure at a low device cost. Since the curable sealing material is a cyanoacrylate resin composition, it becomes a three-dimensional after curing. Cross-linked non-hydrolyzable water barrier (first water barrier).

In addition, the trace amount of water present on the surface of the covered electric wire or the surface of the connection part functions as an initiator, anionically polymerizes the cyanoacrylate resin composition around the water, and forms the anionically polymerized resin that becomes the second waterproof wall to cure. Therefore, even if a small amount of water that breaks through the first water barrier penetrates into the vicinity of the core wire, the second water barrier can completely prevent water from entering the gap between the core wires.

In addition, in the present invention, the photocurable resin composition is a chemical reaction type resin composition capable of radical polymerization by irradiation with light.

In the photocurable cyanoacrylate resin composition used in the present invention, the cured product must have a tensile elongation at break of 20% or more. The tensile elongation at break of the cured product is based on the dumbbell-shaped No. 3 sample piece made according to JIS K6251 at 23°C and a relative humidity (RH) of 50%, using the condition of a tensile speed of 10mm/min The value measured by the tensile testing machine.

Generally speaking, the cured product of the cyanoacrylate resin composition is hard and brittle, and the tensile elongation at break of the cured product is less than 5%. When thermal shock is given to the cured product of such a general-purpose cyanoacrylate resin composition, cracks are generated. Therefore, when using such a general-purpose cyanoacrylate resin composition, there is a possibility that sufficient waterproof performance cannot be maintained, but the present invention uses a cyanoacrylate resin composition having a cured tensile elongation at break of 20% or more. The photocurable cyanoacrylate resin composition dramatically improves the thermal shock resistance, so the occurrence of such cracks is prevented, and as a result, the connection part of the electric wire can be reliably waterproofed. Specifically, durability such as heat resistance, cold resistance, heat and humidity resistance, thermal shock resistance, water resistance, and salt water resistance required for automobile harnesses can be satisfied, and highly reliable waterproofing can be performed.

A photocurable cyanoacrylate resin composition having such a cured tensile elongation at break of 20% or more is obtained by blending, for example, intramolecularly A photopolymerizable resin component having at least one of two acryloyl groups and methacryloyl groups can be completed.

Here, as the photocurable cyanoacrylate resin composition used in the present invention, it is desirable to contain the following (B) in addition to the following (A) and (C).

(A) 2-cyanoacrylate

(B) A photopolymerizable resin component having at least one of two acryloyl groups and methacryloyl groups in the molecule

(C) Photoradical polymerization initiator

Here, these respective components will be described in more detail.

(A) 2-cyanoacrylate is an anionically polymerizable and radically polymerizable monomer, and serves as a main component of a photocurable cyanoacrylate resin composition. For such 2-cyanoacrylates, all 2-cyanoacrylates widely used as the main component of cyanoacrylate-based instant adhesives are suitable. Preferred 2-cyanoacrylates are compounds represented by the following formula I.

Formula I

(In the above formula, R is alkyl, cycloalkyl, haloalkyl, alkoxyalkyl, alkenyl, cycloalkenyl, alkynyl or aryl.)

Preferred 2-cyanoacrylate, R in the above formula I is an alkyl, cycloalkyl, haloalkyl, alkoxyalkyl, alkenyl, cycloalkenyl, alkynyl group with 1 to 8 carbon atoms Or an aryl group, as preferred specific examples, 2-methyl cyanoacrylate, ethyl 2-cyanoacrylate, n-propyl 2-cyanoacrylate, isopropyl 2-cyanoacrylate, etc. 2-cyanoacrylate alkyl esters, 2-n-butyl cyanoacrylate, 2-isobutyl cyanoacrylate, n-octyl 2-cyanoacrylate and other 2-cyanoacrylate alkyl esters, R is unsaturated 2-cyanoacrylate Allyl ester, 2-cyanoacrylate propargyl 2-alkenyl cyanoacrylate or 2-alkynyl cyanoacrylate, 2,2,2-trifluoroethyl 2-cyanoacrylate, 2-cyanoacrylate 2, 2, 3, 3-tetrafluoropropyl acrylate and other 2-fluoroalkyl cyanoacrylates, 2-methoxyethyl cyanoacrylate, 2-ethoxyethyl cyanoacrylate and other 2- Alkoxyalkyl cyanoacrylates, but not limited to these. These 2-cyanoacrylates may be used by 1 type or in mixture of several types.

More preferred 2-cyanoacrylates used in the present invention are ethyl 2-cyanoacrylate, n-propyl 2-cyanoacrylate, isopropyl 2-cyanoacrylate, n-butyl 2-cyanoacrylate, Isobutyl 2-cyanoacrylate, Methoxyethyl 2-cyanoacrylate, Ethoxyethyl 2-cyanoacrylate.

(B) The photopolymerizable resin component having at least one of two acryloyl groups and methacryloyl groups in the molecule used in the present invention, as long as it is a cured product of a photocurable cyanoacrylate resin composition A photopolymerizable resin component capable of imparting elongation is sufficient. Specifically, the following photopolymerizable resin components are mentioned.

Polyethylene glycol di(meth)acrylate (commercially available: Aronix M-260: manufactured by Toagosei Co., Ltd., NK Ester A-600, 23G: manufactured by Shin-Nakamura Chemical Industry Co., Ltd., etc., the same below), polyethylene glycol Propylene glycol di(meth)acrylate (Aronix M-270: manufactured by Toagosei Co., Ltd., NK ester APG-700: manufactured by Shin-Nakamura Chemical Co., Ltd., etc.), urethane (meth)acrylate (Aronix M- 1310: manufactured by Toagosei Co., Ltd., UV3000B: manufactured by Nippon Gosei Chemical Industry Co., Ltd., etc.), polyester (meth)acrylate (Aronix M-6100: manufactured by Toagosei Co., Ltd., KAYARAD HX-620: manufactured by Nippon Kayaku Co., Ltd. etc.), EO-modified di(meth)acrylate of bisphenol A (Aronix M-210: manufactured by Toagosei Co., Ltd., etc.), but not limited to these. One type of these photocurable resins may be used, and several types may be mixed and used. In addition, the above-mentioned "(meth)acrylate" means either "methacrylate" or "acrylate" (the same applies hereinafter).

Even among these photocurable resins, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate are preferred Acrylate.

In addition, in order to make the cured product of the curable sealing material excellent in thermal shock resistance, the glass transition temperature (Tg) of the cured product of the photocurable resin is preferably lower than or equal to 0°C. The lower limit is not particularly limited, but higher than or equal to -50°C is realistic in consideration of adhesiveness.

The amount of these photocurable resin components to 2-cyanoacrylate is based on the total amount of the two. The photocurable resin component is preferably greater than or equal to 1% by weight, less than or equal to 50% by weight, more preferably It is greater than or equal to 10% by weight and less than or equal to 40% by weight. If the compounding amount of the photocurable resin component is less than 1% by weight, sufficient elongation may not be given to the cured product after curing. On the other hand, if it exceeds 50% by weight, the viscosity of the resin composition increases, and the resin composition It often does not penetrate into the gaps between core wires, etc., and there are problems such as momentary adhesiveness becomes slow.

The so-called (C) photoradical polymerization initiator used in the present invention uses hydrogen abstraction or cracking caused by light irradiation to make (A) 2-cyanoacrylate and (B) have two acryloyl and methacryloyl groups As the photoradical polymerization initiator for starting the radical polymerization of at least one photopolymerizable resin component, known photoradical polymerization initiators can be used. Specifically, the following photoradical polymerization initiators are mentioned.

(1) As the type of hydrogen abstraction, there are benzophenones such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, benzil, 4,4'- benzils such as dimethoxybenzil, ketones such as camphorquinone, and the like.

(2) As the type of photocleavage, there are benzoin such as benzoin, benzoin methyl ether, benzoin ether, acetophenone, 4-phenoxydichloroacetophenone, 4-tert-butyl-dichloro Acetophenones such as acetophenone, α-hydroxy ketones such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, methyl isobutyryl -methyl phosphinate, methyl isobutyryl-phenyl phosphinate, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzyl Acylphosphine oxides such as acyl)-phenylphosphine oxide and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, etc., are not limited thereto. These photoradical polymerization initiators may be used alone or in combination.

Even among these photoradical polymerization initiators, α-hydroxyketones and acylphosphine oxides are preferably selected from the viewpoint of photocurability. These photoradical polymerization initiators contain 0.01 wt. %, less than or equal to 10% by weight, preferably greater than or equal to 0.1% by weight, less than or equal to 5% by weight.

○Other ingredients

In the photocurable cyanoacrylate resin composition used in the present invention, as required components, the following stabilizers, polymerization accelerators, polymerization initiators, and Agents, thickeners and other additives.

[stabilizer]

It is an additive for improving the storage stability of the curable sealing material, and anionic polymerization stabilizers such as sulfur dioxide, nitrogen monoxide, hydrogen fluoride, sultone compounds, BF3 complexes, methanesulfonic acid, p-toluenesulfonic acid, or Free radical polymerization stabilizers such as hydroquinone, hydroquinone monomethyl ether, catechol, and 1,2,3-glucinol.

[polymerization accelerator]

It is an additive for improving the anionic polymerizability of the curable sealing material, or an additive for increasing the bonding speed, and examples thereof include crown ethers, silacrown ethers, and calixallenes.

[polymerization initiator]

It is an additive to improve the radical polymerizability of curable sealing materials, and organic peroxides such as di-tert-butyl hydroperoxide and cumene hydroperoxide are added.

[thickener]

The photocurable cyanoacrylate resin composition of the present invention has a viscosity of 200 mPa·s or less at 25° C. In order to adjust the permeability to electric wires within this range, a thickener can be used, such as Polymethyl methacrylate, methyl methacrylate/(meth)acrylate copolymer, cellulose derivatives, etc.

In addition to the above, an adhesion imparting agent, a dye, a fragrance, a filler, a crosslinking agent, a toughening agent, and the like are added according to the purpose. Regarding these, all conventionally known techniques can also be used.

With the photocurable cyanoacrylate resin composition used in the present invention, the viscosity at 25°C must be less than or equal to 200mPa·s when measured with an E-type viscometer, and the preferred viscosity is less than or equal to 100mPa·s . When the viscosity of the curable sealing material is higher than 200 mPa·s, the penetration of the curable sealing material into the gap between the core wires by capillary phenomenon becomes insufficient. The thickness becomes thinner, or almost lost, and cannot reflect a sufficient waterproof effect.

The method of waterproofing the connection portion of the covered electric wire according to the present invention will be described in detail below with reference to the drawings.

In the connection processing part 200 at the end of the electric wire shown in FIG. The covering portion 71a near the connecting portion 75 of the electric wire 71 is made of insulating synthetic resin that transmits electromagnetic waves of 200 to 500 nm, and is covered by a bottomed cylindrical protective cap 60 that protects the connecting portion of the covered electric wire. Then fill the curable sealing material (photocurable cyanoacrylate resin composition) 65 between the above-mentioned protective cap 60 and the core wire 71b and the covering part 71a near the core wire 71b forming the connection part 75, and pass through the light Radical polymerization occurs upon irradiation to form a thick, firm layer.

[connection method of electric wire]

A method of connecting electric wires in such an electric wire end connection processing unit 200 will be described. First, after removing the covering portion 71a at the end of several electric wires 71 to expose each core wire 71b, the respective electric wires 71 are made to run along each other so that the tips are substantially aligned. Then, the core wires 71b of each electric wire 71 are adhered to each other by welding or crimping to form a connection portion 75 for electrically connecting the core wires 71b to each other, and the wire assembly 70 shown in FIG. 2 is manufactured.

[Impregnation method into curable sealing material, gap between core wires and sealing method between wires]

Next, as shown in FIG. 3 , insert the end portion of the above-mentioned electric wire assembly 70 into the curable sealing material 65 in the bottomed cylindrical protective cap 60 in which the curable sealing material 65 has been injected in advance, and then not only the connecting portion 75 and the core wire 71b, and the covering portion 71a in the vicinity of the core wire 71b is immersed in the curable sealing material 65 described above. Here, the covering portion 71a in the vicinity of the core wire 71b usually means that the covering portion is 3 mm or more and 20 mm or less. If the covering part is too short, there is a danger that waterproof reliability will be lowered. If it is too long, the processing part will become too large. The layer of the above-mentioned curable sealing material 65 is relatively thick, and short-term curing by anionic polymerization does not occur, so it can be easily inserted into the terminal portion of the above-mentioned wire assembly 70, and since the viscosity at 25° C. in an uncured state is less than Or equal to 200mPa·s curable sealing material 65, so the permeation speed to the gap between the core wires by capillary phenomenon is fast, after the end portion of the above-mentioned electric wire assembly 70 is inserted for a few seconds, the curable sealing material 65 is just fully completed. Saturation of gaps between lines. The portion of the impregnated curable sealing material 65 in contact with the surface of the core wire undergoes anionic polymerization using moisture present on the surface of the core wire as an initiator, and adheres to the core wire to function as a waterproof sealant (sealing layer). In addition, the curable sealing material 65 permeates between the electric wires, spreads, and does not come into contact with the light from the outside of the protective cap 60. The moisture present on the surface of the covering part 71a is also used as an initiator to anionically polymerize and solidify. The waterproof sealing material (sealing layer) functions.

[Photocuring method and sealing method of curable sealing material]

The uncured portion of the curable sealing material 65 filled between the terminal insertion portion of the above-mentioned wire assembly 70 and the protective cap 60 is, for example, irradiated with visible light or Ultraviolet rays or both can easily undergo radical polymerization, and can complete the photocuring of the connecting portion 75, the core wire 71b, and the photoirradiable portion of the coating portion 71a near the core wire 71b (connecting portion 75) in a short time.

[Electromagnetic wave irradiation source and amount necessary for curing]

Examples of the electromagnetic wave irradiation source used in the present invention include low-pressure mercury lamps, high-pressure mercury lamps, xenon lamps, metal halide lamps, and the like. The electromagnetic wave must be an electromagnetic wave of a wavelength capable of curing the curable sealing material, but it is usually ultraviolet rays and visible light of 200 to 500 nm. The amount of light that passes through the protective cap 60 necessary for the photocuring of the curable sealing material is affected by the type and amount of the photopolymerization initiator blended in the curable sealing material used, so it cannot be limited. Or equal to 100mJ/cm ² , particularly preferably greater than or equal to 200mJ/cm ² , less than or equal to 10000mJ/cm ² .

[protective cap]

The material of the protective cap is sufficient as long as it is insulative and transmits electromagnetic waves of a wavelength that can cure the curable sealing material used, usually a material of electromagnetic waves of 200 nm or more and 500 nm or less. Resins such as soft vinyl chloride resin, polypropylene, polyethylene, polysiloxane, acrylic, polycarbonate, polyester, polyamide, polytetrafluoroethylene, but not limited to these.

The shape of the protective cap is not limited as long as it can protect the connecting part of the covered wire from electrical, mechanical or chemical impact, such as a bottomed cylindrical shape, a cone shape, a bucket shape, etc. Regarding the opening and the concave part The shape can be defined as an arbitrary shape in order to facilitate insertion into the connecting portion of the covered electric wire.

Furthermore, instead of supplying electromagnetic waves through the protective cap, but using other methods to supply electromagnetic waves to the curable sealing material, for example, an optical fiber is introduced into the curable sealing material together with the covering part of the covered electric wire, and the optical fiber is used as the introduced light. As a means, when electromagnetic waves or the like are supplied to the curable sealing material, the protective cap can be made of a material that does not transmit electromagnetic waves of the wavelength of the curable sealing material used. In this case, the optical fiber can be cut at an appropriate position after the curable sealing material is cured.

As described above, in the present invention, the connection treatment part of the covered electric wire is inserted into the protective cap containing a certain kind of photocurable cyanoacrylate resin composition with low viscosity and relatively high elongation, and after dipping, the electromagnetic wave is irradiated. With a simple process, extremely simple, rapid, low-cost, and reliable waterproofing can be performed on the connecting portion of the electrically connected covered electric wire.

Example

Hereinafter, examples are given and the present invention will be described in more detail. In addition, the performance evaluation in each Example and a comparative example was performed by the following method.

<protective cap>

Made of soft vinyl chloride resin, thickness: 1mm

<wire assembly>

An electric wire assembly formed by crimping the core wires at one end of ten covered electric wires

<Photocurable cyanoacrylate resin composition>

Curable sealing materials having the compositions shown in Table 1 and Table 2 were prepared, and respective characteristics were evaluated as follows. In addition, for comparison, the curable sealing material of the composition shown in Table 3 was also examined similarly.

[viscosity]

The viscosity at 25° C. was measured using an E-type viscometer.

[Coagulation time (set time)]

According to JIS K6861, using a copper test piece (test piece), the time when the specified bond strength is reached is taken as the setting time.

[Photocurability]

The cumulative amount of light required to cure a thickness of 2 mm was measured using a Cornbea light irradiator (metal halide lamp 1500w) manufactured by Aigraficus Co., Ltd. In addition, the measurement of light quantity was performed using the photoreceiver UVD-C365 which has a center light-receiving center in wavelength 365nm, and the integrated light quantity meter UIT-150 manufactured by Usio Electric Co., Ltd.

[Tensile elongation at break]

Tensile elongation at break of the cured product, for a dumbbell-shaped No. 3 sample piece (thickness 2mm) made in accordance with JIS K6251, at 23°C and a relative humidity of 50%, at a tensile speed of 10mm/min Under the conditions, use a tensile testing machine to measure.

[curable sealing material suction height]

Inject 1 g of curable sealing material into the protective cap with a glass straw, insert the wire assembly therein, and use a light irradiator (high-pressure mercury lamp 600 W) made by Aigrafix to irradiate light from both sides sandwiching the protective cap (accumulated light amount : 6000mJ/cm ² ). After 24 hours, the insulator portion of the electric wire thus subjected to the waterproof treatment was cut, and the suction height of the curable sealing material was measured.

[Heat and cold shock resistance]

The thermal shock test was performed on the electric wires subjected to the waterproof treatment in the same manner as above, and the number of cycles until cracks occurred in the curable sealing material was measured.

Test conditions: Temperature conditions: 100°C, 60 minutes. Cold conditions: -40°C, 60 minutes.

In addition, the ellipsis in Table 1 represents the following compounds (however, Tg in parentheses represents the glass transition temperature of the cured product of the compound).

M-1310: polyol type urethane diacrylate (Tg: -25°C), HX-620: polyester diacrylate (Tg: -8°C), M-225 (Tg: -8°C) and M-270 (Tg: -32°C): Polypropylene glycol diacrylate, M-260: Polyethylene glycol diacrylate (Tg: -34°C), M-220: Tripropylene glycol diacrylate (Tg: 90°C ), DPHA: dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (Tg: >250° C.). Irg819: bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, Irg1800: 1-hydroxy-cyclohexyl-phenyl-ketone and bis(2,6-dimethoxybenzoyl )-2,4,4-Trimethylpentylphosphine oxide in a weight ratio of 75:25 mixture, DC1173:2-hydroxyl-2-methyl-1-phenyl-propane-1-one, Irg184:1 -Hydroxy-cyclohexyl-phenyl-ketone. PMMA: polymethyl methacrylate.

Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Components (mixing amount (weight %) (A) 2-cyanoacrylate Isobutyl ester (50) Isobutyl ester (70) Isobutyl ester (90) Isobutyl ester (70) Isobutyl ester (70) (B) Photopolymer resin M-1310(50) M-1310(30) M-1310(10) HX-620(30) HX-620(30) (C) Photoradical polymerization initiator Irg819(3) Irg819(3) Irg819(3) Irg819(3) Irg819(3) thickener PMMA(3) evaluate viscosity mPa·s 30 13 10 10 140 solidification time Second 90 10 5 10 20 Photocurable mJ/ ^cm2 4000 4000 6000 4000 4000 Tensile elongation at break % 120 105 35 40 20 Wire suction height mm 15 30 30 30 5 Cold and heat shock resistance Cycles >1000 >1000 600 600 300

Table 2 Example 6 Example 7 Example 8 Example 9 Components (mixing amount (weight %) (A) 2-cyanoacrylate Isobutyl ester (70) Isobutyl ester (70) Isobutyl ester (70) Ethoxyethyl ester (70) (B) Photopolymer resin M-225(30) M-260(30) M-270(30) HX-620(30) (C) Photoradical polymerization initiator Irg819(3) Irg1800(3) Irg819(2) Irg819(2) thickener DC1173(2) Irg184(2) evaluate viscosity mPa·s 6 10 8 18 solidification time Second 10 20 10 5 Photocurable mJ/ ^cm2 4000 4000 6000 6000 Tensile elongation at break % 28 80 78 58 Wire suction height mm 35 30 30 30 Cold and heat shock resistance Cycles 100 >1000 >1000 >1000

table 3 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Components (mixing amount (weight %) (A) 2-cyanoacrylate Isobutyl ester (70) Isobutyl ester (70) Isobutyl ester (70) Ethyl ester (100) (B) Photopolymer resin M-220(30) DPHA(30) HX-620(30) (C) Photoradical polymerization initiator Irg819(3) Irg819(3) Irg819(3) thickener PMMA(5) Ethyl ferrocene (5) evaluate viscosity mpa s 5 10 550 2 solidification time Second 10 10 30 3 Photocurable mJ/ ^cm2 4000 2000 - 2000 Tensile elongation at break % 5 0 - 3 Wire suction height mm 35 30 0 35 Cold and heat shock resistance Cycles 0 0 - 0

"-" in the table indicates that no evaluation was performed.

It can be judged from Tables 1 to 3 above that the photocurable cyanoacrylate resin composition used in the present invention has a viscosity of less than or equal to 200mPa·s and a tensile elongation at break of greater than or equal to 20%. , With such a photocurable cyanoacrylate resin composition, the solidification times related to productivity are all less than or equal to 180 seconds, so good productivity can be ensured, and the photocurability is excellent even for low-cost devices. It is less than or equal to 10000mJ/cm ² required to ensure good productivity. In addition, it can be seen that the wire suction height of 5mm or higher to obtain sufficient waterproofness is satisfied. In addition, it has resistance to environmental changes or impact resistance during long-term use. The resistance of more than or equal to 100 times is necessary in the cold and heat shock resistance of the permanent target.

In addition, when the connection part of the embodiment of the invention of the present application is applied to the wiring harness for automobiles, when the test is carried out under the environment that can be considered in the actual automobile, it is confirmed that the connection part of the embodiment of the present invention maintains Full water resistance.

Industrial Applicability

The present invention can perform simple, rapid, low-cost, and reliable waterproof treatment on the connecting portion of electrically connected covered electric wires that can be used in harnesses for automobiles and the like.

According to the present invention, since the intrusion of moisture into the insulating member is suppressed, there is no corrosion of the core wire or leakage of current flowing in the electric wire due to intrusion of moisture into the inside of the coating, and the reliability of water resistance and salt water resistance is improved.

Claims (3)

1. The method of waterproofing the connection portion of the covered electric wire is to inject a curable sealing material into the protective cap protecting the connection portion of the covered electric wire, and then insert the connection portion of the covered electric wire and the vicinity of the connection portion of the covered electric wire into the sealing material. A coating part, followed by curing the curable sealing material, a method for waterproofing the connection part of the covered electric wire, characterized in that the curable sealing material has a viscosity of less than or equal to 200 mPa·s at 25° C. in an uncured state, and is cured A photocurable cyanoacrylate resin composition having a post-tensile elongation at break greater than or equal to 20%. by electromagnetic waves. 2. The method for waterproofing the connection part of the covered electric wire according to claim 1, wherein the above-mentioned photocurable cyanoacrylate resin composition contains the following (A), (B) and (C) , and the tensile elongation at break of the cured product of the photocurable cyanoacrylate resin composition is greater than or equal to 20%, (A) 2-cyanoacrylate, (B) a photopolymerizable resin component having at least one of two acryloyl groups and methacryloyl groups in the molecule, (C) Photoradical polymerization initiator. 3. The method for waterproofing the connection part of the covered electric wire according to claim 1 or 2, wherein the above-mentioned protective cap is made of a material that can transmit the above-mentioned electromagnetic wave, and the electromagnetic wave of the above-mentioned wavelength is transmitted from the outside of the protective cap. The above-mentioned curable sealing material is irradiated through the protective cap.

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