Composition for sealing coated electric wire and method for sealing coated electric wire

Abstract

The present invention provides a sealing composition for a coated electric wire and a sealing method, which are excellent in sealing properties even under conditions such as cold-heat cycles or high temperature and high humidity. The sealing composition for a coated electric wire is used for sealing a core wire connecting portion formed by electrically connecting a plurality of core wires exposed from a plurality of coated electric wires, and is characterized in that a hardening time at 130°C is 10 minutes or less, and when a portion in which the core wires including the core wire connecting portion are exposed and a boundary portion between the covered portion and the exposed portion of the core wires are vertically dipped and heat-hardened in the sealing composition for a coated electric wire filled in a resin cover, the dipped portion penetrates into the inside of the coated electric wire with a height of 5 mm or more at the hardening time point.

Description

Technical Field

[0001] This invention relates to a sealing composition and sealing method for coated wires that exhibit excellent sealing performance even under conditions such as thermal cycling or high temperature and humidity. It is widely used as a sealant and sealing method for coated wires in the wiring of various electrical systems, such as automobiles, home appliances, and office automation equipment. Background Technology

[0002] In automotive electrical components, wiring harnesses and other wires sometimes connect multiple wires at their ends for branching purposes. This connection is achieved, for example, by stripping the coating from the ends of multiple coated wires to expose the core wires, and then connecting the exposed core wires using a connector. To improve circuit reliability, these wire connections need to be insulated from the outside, and to be waterproofed, they need to be sealed. Various sealing methods have been researched.

[0003] Conventionally, it is known to seal the core wire connection using thermosetting resin. However, for a perfect seal, the thermosetting resin must fully penetrate the narrow gaps in the core wire connection, such as the gaps between the core wires, the gaps between the coated wires, and the gaps between the core wires and their coating. Therefore, the viscosity of the thermosetting resin needs to be low. Generally, in manufacturing products using thermosetting resins, curing at relatively high temperatures can improve productivity. However, in this application, because the thermosetting resin thickens due to the curing reaction before fully penetrating the gaps, it cannot be cured at high temperatures.

[0004] In contrast, Patent Document 1 describes a sealing method for a core wire connection, which is a core wire connection formed by electrically connecting multiple core wires exposed from multiple covered wires. The sealing method is characterized in that the core wire connection is immersed in a thermosetting resin and the thermosetting resin is cured within a temperature range in which the resin viscosity is maintained at less than 1 Pa·sec for at least one minute.

[0005] In the sealing method, by immersing the core wire connection in a thermosetting resin heated in a temperature range where the curing progress is relatively slow, and curing it within that temperature range, a relatively long time can be ensured before the viscosity rises sharply due to curing. Therefore, it has the following advantages: the thermosetting resin can fully penetrate into narrow gaps such as the gaps between core wires, the gaps between coated wires, and the gap between the core wire and its coating layer in the core wire connection.

[0006] However, in the invention described in Patent Document 1, by immersing the core wire connector in a thermosetting resin heated within a temperature range where curing progresses relatively slowly, and curing it within that temperature range, a relatively long time is ensured before the viscosity increases sharply due to curing, resulting in a long time before curing. Specifically, according to the embodiment, the curing of the thermosetting resin requires more than 10 minutes, thus resulting in poor production efficiency.

[0007] Therefore, it is unknown whether high-temperature curing is employed to improve production efficiency when using thermosetting resin to seal the core wire connection, and what methods are used to perfect the seal under these conditions.

[0008] [Existing Technical Documents]

[0009] [Patent Literature]

[0010] Patent Document 1: Japanese Patent Application Publication No. 2007-317470 Summary of the Invention

[0011] [The problem the invention aims to solve]

[0012] The present invention aims to provide a sealing composition and method for coated wires that exhibit excellent sealing performance even under conditions such as thermal cycling or high temperature and humidity. The sealing composition can harden within a short time (less than 10 minutes) during the sealing process of the coated wires, thereby improving the production efficiency of the process.

[0013] [Technical means to solve the problem]

[0014] The methods for solving the problem include the following forms.

[0015] <1> A sealing composition for coated wires, used to seal a core wire connection formed by electrically connecting multiple core wires exposed from multiple coated wires, characterized in that the curing time at 130°C is 10 minutes or less, and when the exposed portion of the core wire including the core wire connection and the boundary portion between the coated portion and the exposed portion of the core wire are vertically immersed in the sealing composition for coated wires filled with resin and heated for curing, the composition penetrates into the interior of the coated wires at a height of 5 mm or more at the curing time point.

[0016] <2> The sealing composition for coated wires according to <1> is characterized in that the curing time at 130°C is 4 minutes or less.

[0017] <3> The sealing composition for coated wires according to <1> or <2> comprises an epoxy component and a hardening component.

[0018] <4> The sealing composition for coated wires according to <3>, wherein the epoxy component is mainly composed of epoxy resin with four or fewer epoxy groups per molecule.

[0019] <5> The sealing composition for coated wires according to <3> or <4>, wherein the epoxy component is mainly composed of bisphenol A type epoxy resin and / or bisphenol F type epoxy resin.

[0020] <6> The sealing composition for coated wires according to <3> is characterized in that the curing component is an amine compound or a mercapto compound.

[0021] <7> The composition for sealing coated wires according to any one of <3> to <6> further contains a reactive diluent.

[0022] <8> The sealing composition for coated wires according to any one of <3> to <7> further contains a coupling agent.

[0023] <9> A method for sealing a coated wire, comprising: a step of filling a resin cover with a sealing composition for coated wire according to any one of <1> to <8>; a step of immersing the exposed portion of the core wire including the core wire connection portion and the boundary portion between the covered portion and the exposed portion in the sealing composition for coated wire; and a step of heating the resin cover to harden the sealing composition for coated wire.

[0024] <10> An electrical wire coated with a hardened material of the coating wire sealing composition according to any one of <1> to <8>.

[0025] [The effects of the invention]

[0026] The sealing composition and sealing method for coated wires according to the present invention maintain the sealing performance of the coated wires even under conditions such as thermal cycling or high temperature and humidity, and can be cured within 10 minutes, thus exhibiting excellent productivity. Attached Figure Description

[0027] Figure 1 This is a schematic diagram showing the state before the exposed portion of the core wire, including the core wire connection portion, and the boundary portion between the covered portion and the exposed portion of the core wire, in the coated wire sealing method of the present invention are immersed in a resin cover filled with the coated wire sealing composition of the present invention.

[0028] Figure 2 This is a schematic diagram showing the state in which the exposed portion of the core wire, including the core wire connection portion, and the boundary portion between the covered portion and the exposed portion of the core wire are immersed in a resin cover filled with the sealing composition for coated wires of the present invention. Detailed Implementation

[0029] The present invention will now be described in detail.

[0030] The sealing method of the present invention is a method of sealing a core wire connection portion formed by electrically connecting multiple core wires exposed from multiple covered wires using a sealing composition, characterized in that the core wire connection portion can be immersed in the sealing composition and hardened by heating at 130°C for no more than 10 minutes.

[0031] The sealing composition of the present invention is characterized in that the curing time at 130°C is 10 minutes or less. When the exposed portion of the core wire, including the core wire connection portion, and the boundary portion between the covered portion and the exposed portion of the core wire are vertically immersed in the sealing composition for coated wires filled with a resin cover and then heated and cured, during curing, the composition penetrates from the boundary portion between the covered portion and the exposed portion into the interior of the coated wire, i.e., between the covered layer and the core wire, at a height of 5 mm or more, thereby achieving the effect of the invention. Furthermore, as... Figure 1 , Figure 2 As shown, the boundary between the covered portion and the exposed portion is substantially parallel to the sealing composition. Furthermore, the sealing composition of the present invention does not necessarily need to be cured at 130°C; it can also be cured at temperatures below that.

[0032] As for the coating wire sealing composition of the present invention, it is preferable that the curing time at 130°C is 7 minutes or less, and more preferably 4 minutes or less. Here, curing refers to a state where the heat curing property is 0 in the evaluation shown in the examples, and the curing time is the shortest time from heating the liquid composition at room temperature according to the procedure of the examples until curing.

[0033] The so-called core wire connection part used in this invention, which electrically connects multiple exposed core wires of multiple covered wires, such as... Figure 1 As shown, this is a core wire connection portion formed by electrically connecting multiple core wires exposed at the ends of multiple covered wires through methods such as splicing, welding, and riveting. Conventionally known core wire connection portions can be used without particular limitation. Here, in Figure 1 In the diagram, 1 represents the covered wire, 2 represents the exposed core wire portion, and 3 represents the connection part (jointer processing part) that electrically connects multiple core wires.

[0034] As the sealing composition for coated wires of the present invention, a so-called two-component thermosetting epoxy resin comprising an epoxy component and a curing component is preferred because it is less prone to cracking in the sealed portion after curing.

[0035] The epoxy component in the coating wire sealing composition of the present invention is preferably an epoxy resin with four or fewer epoxy groups per molecule as the main component.

[0036] If the number of epoxy groups exceeds 4, the crosslinking density with the hardening component increases in a very short time. When the core wire connection is vertically immersed in the coating wire sealing composition of the present invention, the composition will not penetrate into the interior of the coated wire at a height of more than 5 mm, and the effect of the present invention may not be achieved.

[0037] Here, the term "main component" refers to a component that accounts for 50% or more by mass of all epoxy components, more preferably 80% or more by mass.

[0038] Examples of epoxy components in the sealing composition for coated wires of the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether-based epoxy resins such as 1,4-cyclohexanediethanol diglycidyl ether and phthalate diglycidyl ether, and glycidyl ester-based epoxy resins such as tetrahydrophthalic acid diglycidyl ester and hexahydrophthalic acid diglycidyl ester. In terms of greatly improving the adhesion between the coated wire and the core wire and the coating material, bisphenol A type epoxy resin and / or bisphenol F type epoxy resin are preferred as the main components.

[0039] The bisphenol A type epoxy resin is preferably in liquid form at room temperature (25°C), and its viscosity is preferably below 40 Pa·s, and more preferably below 25 Pa·s.

[0040] In addition, the epoxy equivalent of the bisphenol A type epoxy resin is preferably 225 or less.

[0041] On the other hand, the bisphenol F type epoxy resin is preferably liquid at room temperature (25°C) and its viscosity is preferably 15 Pa·s or less, and more preferably 5 Pa·s or less.

[0042] In addition, the epoxy equivalent of the bisphenol F type epoxy resin is preferably 190 or less.

[0043] The hardening component in the coating wire sealing composition of the present invention is preferably an amine compound or a mercapto compound.

[0044] By using these compounds, it is easy to obtain the effect of hardening the formulation within 10 minutes under heating conditions of 130°C.

[0045] Examples of amine compounds include chain aliphatic polyamines, cyclic aliphatic polyamines, aromatic polyamines, modified amines, and polyaminoamides (polyamide resins). For the reasons of good compatibility with epoxy resins and excellent safety, modified amines and polyamide resins obtained from aliphatic polyamines are preferred.

[0046] These compounds are preferably those that are uniformly dispersed or dissolved with the epoxy component.

[0047] Regarding the amount of these compounds, the amino or thiol groups in these compounds are preferably set to 0.5 to 1.5 moles relative to 1 mole of epoxy groups in the epoxy component.

[0048] In the coating wire sealing composition of the present invention, it is preferable that, in addition to epoxy resin and curing components, a reactive diluent is also contained.

[0049] The reactive diluent reduces viscosity without impairing the properties of the epoxy resin, thus reducing the viscosity of the coated wire sealing composition of the present invention and improving permeability when the core wire connection portion is impregnated in the coated wire sealing composition.

[0050] Examples of reactive diluents include alkyl monoglycidyl ethers and alkyl diglycidyl ethers.

[0051] The reactive diluent is preferably one that can be uniformly mixed or dissolved with the epoxy resin.

[0052] In the sealing composition for coated wires of the present invention, it is preferable to further contain a coupling agent. The coupling agent may be, for example, a silane coupling agent having one or more alkoxysilyl groups in one molecule. Examples of silane coupling agents include alkylalkoxysilanes, aminoalkoxysilanes, epoxyalkoxysilanes, vinylalkoxysilanes, and (meth)acrylates containing alkoxysilyl groups.

[0053] Coupling agents improve the adhesion between the coated wire and the core wire and the coating material.

[0054] The coupling agent is preferably one that can be uniformly mixed or dissolved with the epoxy component.

[0055] The coupling agent is preferably prepared in the form of 0.1 to 5 parts by weight relative to 100 parts by weight of epoxy component.

[0056] Various methods can be exemplified for sealing coated wires using the coating wire sealing composition of the present invention, but for the sake of ensuring water tightness and insulation, a method including the following steps is preferred.

[0057] (1) The process of filling the resin cover with the composition for sealing the covered wires.

[0058] (2) The process of immersing the exposed portion of the core wire, including the core wire connector, and the boundary portion between the covered portion and the exposed portion of the core wire in the sealing composition for the covered wire.

[0059] (3) The process of heating the resin cover to harden the sealing composition for the coated wires.

[0060] Examples of resin covers used in the process include resin covers made of vinyl chloride resin and heat-shrinkable covers containing polyolefin resins, etc.

[0061] The sealing composition for the coated wires is filled into the resin cover using a dispenser or similar device. The filling amount should be sufficient to fully impregnate the entire exposed portion of the core wire, including the core wire connection, and the portion at the boundary between the covered and exposed portions of the core wire.

[0062] Next, the sealant is impregnated in the cover containing the sealing composition for the coated wire, such that the entire exposed portion of the core wire, including the core wire connection, and the boundary between the covered portion and the exposed portion of the core wire are covered by the composition. The resin cover functions to protect the connection portion of the coated wire. By placing the sealing composition for the coated wire into the resin cover and impregnating the entire exposed portion of the core wire, including the core wire connection, and the boundary between the covered portion and the exposed portion of the core wire, the sealing composition for the coated wire hardens, thereby allowing a protective cover to be installed at the connection portion of the coated wire.

[0063] The resin cover is then heated to harden the sealing composition for the coated wires.

[0064] As a heating element, heaters, infrared, laser, microwave, induction heating, etc. can be listed, but in terms of the simplicity of the device, a heater using a heating element is preferred, and a block heater (registered trademark) that is suitable for the shape of the resin cover is preferred.

[0065] In this invention, the heating temperature is measured by placing a test tube filled with oil into a block heater and placing a thermocouple in the oil.

[0066] In addition, heating can also be performed after the exposed portion of the core wire, including the core wire connection portion, and the boundary portion between the covered portion and the exposed portion of the core wire are immersed in the coated wire sealing composition filled in the resin cover. However, in order to speed up the curing time, it is preferable to preheat the resin cover.

[0067] The exposed portion of the core wire, including the core wire connector, and the boundary between the covered portion and the exposed portion of the core wire are preferably immersed in a direction substantially perpendicular to the liquid surface of the sealing composition for coated wires within the resin cover. While an angle can be used during immersion, vertical immersion is preferred to ensure that the sealing composition for coated wires penetrates the interior of multiple coated wires at a uniform height. The angle at which the coated wires are immersed relative to the liquid surface of the sealing composition for coated wires is preferably in the range of 85° to 95°; within this range, vertical immersion is considered acceptable.

[0068] The sealing composition for coated wires of the present invention satisfies the following: (1) it is cured at 130°C for no more than 10 minutes; and (2) when the portion of the core wire including the core wire connection and the boundary portion of the core wire covering and the exposed portion are vertically immersed in the sealing composition for coated wires filled in the resin cover and heated for curing, the sealing composition for coated wires penetrates into the interior of the coated wire at a height of 5 mm or more during curing.

[0069] If only condition (2) is met, the heating temperature can be suppressed simply by reducing the viscosity of the sealing composition for the coated wires; however, this results in poor workability. On the other hand, as the composition hardens with heat, its viscosity increases sharply, and the rate of increase depends on the temperature. Therefore, it is considered that the time until complete hardening at high temperatures is too short to penetrate into narrow gaps such as the gaps between core wires, the gaps between coated wires, and the gap between the core wires and the coating layer in the core wire connection, thus forming an incomplete coating layer. Therefore, the condition of forming a complete coating layer at a high curing temperature of 130°C has not been considered. In addition, the resin cover will undergo thermal deformation at temperatures exceeding 130°C, so 130°C is preferred.

[0070] The coated wire with core wire connection obtained as described above has high airtightness and is preferably used in automotive wiring harnesses, home appliances and OA equipment, etc., which are used in harsh environments.

[0071] [Example]

[0072] The invention will be described in more detail through the following embodiments, but the invention is not limited thereto.

[0073] (Example 1)

[0074] A sealing composition for coated wires is prepared by adjusting 40 parts by weight of a modified aliphatic polyamine as a curing component and 1 part by weight of 3-aminopropyltriethoxysilane as a coupling agent to 100 parts by weight of bisphenol A type epoxy resin.

[0075] Then, as Figure 1 As shown, 0.7g of the composition is injected into a 12mmφ polyvinyl chloride (PVC) shroud. Furthermore, the shroud is housed within a heating block with an opening diameter of 13mmφ, which is suited to its shape.

[0076] On the other hand, prepare the following wire, which is a wire obtained by peeling off the coating layer of the end of a wire with a core wire of 1.5 mm in total diameter coated with 0.3 mm thick vinyl chloride resin, and then combining the five said end parts and processing them with a connector (hereinafter referred to as "wire A").

[0077] Then, as Figure 2As shown, the front 3.5cm of wire A (including the exposed portion of the core wire at the core wire connection and the boundary between the covered portion and the exposed portion of the core wire) is immersed in a PVC-coated wire sealing composition. After being heated by the heating block at 130°C for 5 minutes, it is cooled at room temperature for 1 hour and used as a sample for the immersion length and sealing performance test.

[0078] Similarly, the heat curing properties of the wire A, which was immersed in a PVC-coated wire sealing composition, were confirmed at the time points when heated by the heating block at 130°C for 4 minutes and 130°C for 7 minutes, and are recorded in Table 1.

[0079] In the table, ○, Δ, and × represent the following meanings.

[0080] ○: When the wires inside the cover are lifted, the wires will not shift in position, but will detach from the heating block along with the cover.

[0081] △: When the wires inside the cover are lifted, even though the wires are displaced, the cover will detach from the heating block along with the wires.

[0082] ×: When the wires inside the cover are lifted, the wires will detach from the cover.

[0083] For the specimens used in the penetration length and sealing tests, the penetration length was measured using the following method and recorded in Table 1.

[0084] (Immersion length)

[0085] The PVC coating of the sealed wire was peeled off, and the core wire was unwound to determine the impregnation length of the sealing composition.

[0086] The sealing performance of the test specimens was evaluated using the following evaluation method, and the results are recorded in Table 1.

[0087] (Initial Sealing Evaluation)

[0088] 0.5 kg / cm² is conveyed from the unsealed side of the covered wire. 2 Compressed air was used to immerse the front end of the sealed, coated wire in water to check for any air leaks.

[0089] In the table, ○ and × represent the following meanings.

[0090] ○: No air leakage

[0091] ×: There is an air leak.

[0092] (Sealing performance evaluation after durability testing)

[0093] (1) Heat resistance test

[0094] After the sealed wires were placed at 120°C for 100 hours, the air leakage was investigated in the same manner as the initial sealing evaluation.

[0095] (2) Damp heat resistance test

[0096] After the sealed wires were placed in an environment of 80°C and 95% RH for 100 hours, the air leakage was investigated in the same manner as in the initial sealing evaluation.

[0097] (3) Thermal cycling test

[0098] After the sealed wires are subjected to 100 cycles of temperature cycling from -40℃ for 30 minutes to 120℃ for 30 minutes, the air leakage is investigated in the same manner as the initial sealing evaluation.

[0099] (Example 2)

[0100] The type of wire was changed to the following: the end coating of a wire with a core wire of 2.5 mm in total diameter coated with 0.3 mm thick vinyl chloride resin was peeled off, and two wires were joined together and processed with a connector to obtain a wire (wire B). Otherwise, the coated wire with sealed ends was made in the same manner as in Example 1, and various tests were conducted. The results are recorded in Table 1.

[0101] (Examples 3-10, Comparative Example 1, Comparative Example 2)

[0102] The composition for sealing the coated wire was changed to the composition described in Table 1. Otherwise, coated wires with sealed ends were prepared in the same manner as in Example 2, and various tests were conducted. The results are recorded in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] Bisphenol A type epoxy resin: epoxy equivalent 190g / eq

[0107] Bisphenol F type epoxy resin: epoxy equivalent 166g / eq

[0108] Modified aliphatic polyamine (1): Amine value 440 mg KOH / g

[0109] Modified aliphatic polyamines (2): Amine value 20 mg KOH / g

[0110] Polyamidoamine resin: Cyclic aliphatic polyamidoamine diol diglycidyl ether with an amine value of 490 mg KOH / g; epoxy equivalent 165 g / eq

[0111] According to Table 1, the sealing compositions for coated wires of Examples 1 to 10, which have a curing time of 7 minutes or less at 130°C, exhibit good sealing performance in both initial and durability tests during the process of vertically immersing and heating the exposed portion of the core wire including the core wire connection portion and the boundary portion between the covered portion and the exposed portion of the core wire in the sealing composition filled with a resin cover, and then permeating into the interior of the coated wire at a height of 5 mm or more at the curing time point.

[0112] In the composition of Comparative Example 1, an anhydride was used as the curing component, which has a slower curing time than amine or mercapto-based compositions. Therefore, the curing time at 130°C exceeded 7 minutes, resulting in poor initial sealing.

[0113] On the other hand, in the composition of Comparative Example 2, a material with about six epoxy groups per molecule was used as the epoxy component, which therefore hardened too quickly and the resin did not penetrate into the interior of the coated wire, resulting in poor initial sealing.

[0114] [Explanation of Symbols]

[0115] 1: Covered wires

[0116] 2: Exposed portion of the core wire

[0117] 3: A connector processing section that electrically connects multiple core wires.

[0118] 4: Resin Cover

[0119] 5: Composition for sealing coated wires

[0120] 6: Block heater.

Claims

1. A sealing composition for coated wires, used to seal a core wire connection portion formed by electrically connecting multiple core wires exposed from multiple coated wires, characterized in that the curing time at 130°C is 10 minutes or less, and when the exposed portion of the core wires including the core wire connection portion and the boundary portion between the coated portion and the exposed portion of the core wires are vertically immersed in the liquid coating of the coated wire sealing composition filled in a resin cover, and the coated wire sealing composition is heated and cured at 130°C, at the curing time point, the coating penetrates into the interior of the coated portion from the boundary portion between the coated portion and the exposed portion of the coated wires at a height of 5 mm or more.

2. The sealing composition for coated wires according to claim 1, characterized in that, The hardening time at 130℃ is less than 4 minutes.

3. The sealing composition for coated wires according to claim 1 or 2, comprising an epoxy component and a curing component.

4. The sealing composition for coated wires according to claim 3, wherein, The epoxy component is mainly composed of epoxy resin with four or fewer epoxy groups per molecule.

5. The sealing composition for coated wires according to claim 3, wherein, The epoxy component is mainly composed of bisphenol A type epoxy resin and / or bisphenol F type epoxy resin.

6. The composition for sealing coated wires according to claim 3, characterized in that, The hardening component is an amine compound or a mercapto compound.

7. The sealing composition for coated wires according to claim 3 further comprises a reactive diluent.

8. The sealing composition for coated wires according to claim 3 further comprises a coupling agent.

9. A sealing method for a coated wire, comprising: The steps of filling a resin cover with the sealing composition for coated wires according to any one of claims 1 to 8; immersing the exposed portion of the core wire including the core wire connection portion and the boundary portion between the covered portion and the exposed portion of the core wire in the sealing composition for coated wires; and heating the resin cover to harden the sealing composition for coated wires.

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