Crosslinkable polymer composition, crosslinkable polymer material, insulated electric wire, and wire harness

Abstract

Provided are: a crosslinkable polymer composition in which crosslinkages can be formed by heating and from which a crosslinked body having high heat resistance and abrasion resistance can be provided; a crosslinkable polymer material in which crosslinkages can be formed by heating and which has high heat resistance and abrasion resistance; and an insulated electric wire and a wire harness each provided with the crosslinkable polymer material.　The crosslinkable polymer composition comprises: component A from which a metal ion is released by heat; component B comprising an organic polymer, the organic polymer having a side chain and containing, in the side chain, an electron-withdrawing substituent capable of forming an ionic bond with the metal ion released from the component A; and component C comprising a secondary or tertiary amine represented by formula (1). In the formula: R1 represents a hydrogen atom or a hydrocarbon group having not more than 30 carbon atoms; R2 represents a hydrocarbon group having not more than 30 carbon atoms; and R3 represents a hydrocarbon group having 13-30 (inclusive) carbon atoms.

Description

Crosslinkable polymer composition, crosslinkable polymer material, insulated wire and wiring harness

[0001] The present disclosure relates to a crosslinkable polymer composition, a crosslinked polymer material, an insulated wire, and a wiring harness.

[0002] In insulated wires and wiring harnesses, thermoplastic polymer compositions are often used as insulating members, such as insulating coatings that cover the outer periphery of wire conductors. When molding a thermoplastic polymer composition into a desired shape, it is heated to a flowable state and then a molding method such as extrusion molding is applied. To easily perform molding by heating, it is preferable that the polymer composition acquires flowability without being heated to an extremely high temperature.

[0003] On the other hand, in insulated electric wires and wiring harnesses, a temperature rise occurs when electricity is passed through them, and therefore, polymer compositions arranged in the vicinity of the current-carrying portion, including insulating coatings, are required to have high heat resistance. In other words, the polymer compositions are required not to undergo irreversible deformation due to heat generated when electricity is passed through them. For example, it is desirable that insulating coatings for electric wires for automobiles do not undergo irreversible deformation at temperatures below 190°C. In particular, electric wires for electric vehicles require a large current to flow through the wire conductor, which generates a large amount of heat when electricity is passed through them, and therefore, polymer compositions constituting insulating coatings and the like are required to have high heat resistance.

[0004] Thus, polymer compositions used in insulated wires and wiring harnesses are required to be relatively easily moldable by heating and to have high heat resistance after molding. One approach to achieving both of these properties is to adjust the flow initiation temperature of the thermoplastic polymer material used. However, this approach has limitations, as polymer materials with high flow initiation temperatures require high heating during molding, while polymer materials with low flow initiation temperatures are unlikely to have high heat resistance. Therefore, a method utilizing crosslinking of the polymer material has also been adopted. Specifically, an uncrosslinked polymer composition is molded into a desired shape by extrusion molding or the like, and then the molecular chains are crosslinked to improve heat resistance. Examples of crosslinking methods include electron beam crosslinking, in which a material molded from polyolefin or the like is irradiated with an electron beam to crosslink the molecular chains into a three-dimensional network (see, for example, Patent Document 1), and silane crosslinking, in which a thermoplastic resin containing activated silane groups is molded and then crosslinked upon contact with moisture or the like (see, for example, Patent Document 2). Furthermore, when rubber is used as the polymer material, crosslinking by vulcanization can be used.

[0005] Crosslinking by electron beam crosslinking, silane crosslinking, or vulcanization requires devices such as an electron beam irradiation device, a moisture exposure device, vulcanization equipment, etc. On the other hand, as proposed by the inventors in, for example, Patent Document 3, by using a metal-crosslinkable polymer composition containing a component A from which a metal ion is liberated by heat and a component B composed of an organic polymer having a substituent capable of forming an ionic bond with the metal ion liberated from the component A, when the metal ion is liberated from the component A by heat, the liberated metal ion forms an ionic bond with the substituent of the component B, and the organic polymer of the component B can be crosslinked via the ionic bond.

[0006] JP 2020-176257 A JP 2020-161398 A International Publication No. 2021 / 193811

[0007] As in Patent Document 3, by utilizing ionic bonds between substituents of an organic polymer and metal ions, crosslinks can be formed by heating, resulting in a polymeric material with excellent heat resistance. However, polymeric materials often require mechanical strength, such as abrasion resistance, in addition to heat resistance. For example, in insulated electric wires and wiring harnesses, when contact with other components, such as surrounding devices or adjacent electric wires, is anticipated, it is desirable for the insulating coating to have high abrasion resistance to prevent damage to the insulating coating due to such contact. One method for improving the abrasion resistance of crosslinked polymeric materials is to increase the degree of crosslinking. However, according to the inventors' studies, when using a method for forming crosslinks by ionic bonds between substituents of an organic polymer and metal ions, as in Patent Document 3, it may be difficult to achieve high abrasion resistance. In particular, when a highly flexible organic polymer is used as component B, high abrasion resistance is difficult to achieve.

[0008] In view of the above, an object of the present invention is to provide a crosslinkable polymer composition that can form crosslinks by heating and that gives a crosslinked product having high heat resistance and abrasion resistance, a crosslinked polymer material that can form crosslinks by heating and that has high heat resistance and abrasion resistance, and an insulated wire and a wire harness that include such a crosslinked polymer material.

[0009] The crosslinkable polymer composition according to the present disclosure includes: a component A from which metal ions are liberated by heat; a component B constituted of an organic polymer having side chains containing electron-withdrawing substituents capable of forming ionic bonds with the metal ions liberated from the component A; and a component C constituted of a secondary or tertiary amine represented by the following formula (1): Here, R １ is a hydrogen atom or a hydrocarbon group having 30 or less carbon atoms, R ２ is a hydrocarbon group having 30 or less carbon atoms, R ３ is a hydrocarbon group having 13 to 30 carbon atoms.

[0010] The crosslinked polymer material according to the present disclosure is composed of a material obtained by crosslinking the crosslinkable polymer composition, and includes a crosslinked body obtained by crosslinking the B component with metal ions liberated from the A component, and the C component.

[0011] The insulated wire according to the present disclosure includes a conductor and an insulating coating made of the cross-linked polymer material and covering the outer periphery of the conductor.

[0012] A wire harness according to the present disclosure includes the insulated wire.

[0013] The crosslinkable polymer composition according to the present disclosure can form crosslinks by heating and can provide a crosslinked product having high heat resistance and abrasion resistance. The crosslinkable polymer material according to the present disclosure can form crosslinks by heating and can provide a crosslinked polymer material having high heat resistance and abrasion resistance. Furthermore, the insulated wire and wiring harness according to the present disclosure include such a crosslinked polymer material.

[0014] 1A to 1C are diagrams illustrating the behavior of a crosslinked body contained in a crosslinked polymer material according to one embodiment of the present disclosure when heated, and show states in which the temperature increases in the order of FIG. 1A, FIG. 1B, and FIG. 1C. ２＋ represents a metal ion, and R represents a side chain. Fig. 2 is a cross-sectional view showing the structure of an insulated wire according to one embodiment of the present disclosure.

[0015] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. The crosslinkable polymer composition, crosslinked polymer material, insulated wire, and wire harness according to the present disclosure have the following configurations.

[0016] [1] The crosslinkable polymer composition according to the present disclosure includes: a component A from which a metal ion is liberated by heat; a component B constituted of an organic polymer having a side chain containing an electron-withdrawing substituent capable of forming an ionic bond with the metal ion liberated from the component A; and a component C constituted of a secondary or tertiary amine represented by the following formula (1): Here, R １ is a hydrogen atom or a hydrocarbon group having 30 or less carbon atoms, R ２is a hydrocarbon group having 30 or less carbon atoms, R ３ is a hydrocarbon group having 13 to 30 carbon atoms.

[0017] The crosslinkable polymer composition according to the present disclosure can crosslink component B via metal ions liberated from component A by heating. Therefore, while the uncrosslinked composition exhibits high processability, by heating to form a crosslinked product, a polymer material with high heat resistance can be easily obtained. Furthermore, in the crosslinkable polymer composition according to the present disclosure, the crosslinked structure is formed by ionic bonds, and therefore, flexibility is less likely to decrease due to crosslinking than when a crosslinked structure is formed by covalent bonds. Therefore, the polymer material is less likely to harden due to crosslinking, and even when forming an insulating coating for a large-diameter electric wire, the bending flexibility of the insulating coating is less likely to decrease. Furthermore, in a crosslinked product composed of the crosslinkable polymer composition according to the present disclosure, the reversibility of ionic bonds can be utilized by heating to reshape the crosslinked polymer material. This is because reheating an already formed crosslinked product causes migration of crosslinking points due to ionic bonds, resulting in fluidization of the material.

[0018] Furthermore, the crosslinkable polymer composition according to the present disclosure contains Component C, which is a secondary or tertiary amine having the structure of Formula (1) above, and thereby achieves an improved degree of crosslinking and high abrasion resistance compared to a composition that does not contain Component C. This is thought to be because the amine in Component C is cationized and bonds to the electron-withdrawing substituent in the side chain of Component B, thereby suppressing the rate at which crosslinking of Component B by Component A progresses, allowing crosslinking to proceed with high uniformity throughout the material.

[0019] [2] In the aspect of [1] above, the flow initiation temperature of the crosslinked body may be 190°C or higher and 300°C or lower. By having a flow initiation temperature of 190°C or higher, the crosslinked polymer material does not flow at temperatures below 190°C and has particularly high heat resistance. Highly heat-resistant materials having a flow initiation temperature of 190°C or higher are particularly suitable for use in forming insulating coatings for automotive electric wires. Meanwhile, by suppressing the flow initiation temperature of the crosslinked body to 300°C or lower, remoldability by heating at temperatures of 300°C or lower is ensured.

[0020] [3] In the above embodiment [1] or [2], in the formula (1), R １ is a hydrocarbon group, and R ２ , R ３ The hydrocarbon groups in 2 may each independently be a linear alkyl group or an aromatic ring group, which reduces steric hindrance near the nitrogen atom of component C and effectively inhibits the progression of crosslinking of component B due to metal ions liberated from component A.

[0021] [4] In any one of the above aspects [1] to [3], the component B may have a flow initiation temperature in the range of 50° C. or higher and 190° C. or lower. This makes it easy to obtain a crosslinked product having a flow initiation temperature of 190° C. or higher, and even 300° C. or lower, through crosslinking with metal ions derived from the component A. Furthermore, high moldability is obtained when the uncrosslinked crosslinkable polymer composition is molded into a desired shape by extrusion molding or the like.

[0022] [5] In any one of the above aspects [1] to [4], the component A may have a decomposition point or phase transition point of 50°C or higher and 300°C or lower. This suppresses the release of metal ions from component A during preparation of the crosslinkable polymer composition or before use of the crosslinkable polymer composition, thereby suppressing the progress of crosslinking and achieving high storage stability for the crosslinkable polymer composition, such as suppressing changes in the quality of the crosslinkable polymer composition at low temperatures such as room temperature. On the other hand, because component A undergoes decomposition or phase transition at a moderate temperature, which easily releases metal ions from component A, the crosslinking reaction can proceed at a temperature at which the deterioration of component B does not occur.

[0023] [6] In any one of the above aspects [1] to [5], the A component may have a decomposition point or phase transition point at a temperature equal to or higher than the flow initiation temperature of the B component. This allows the B component to have fluidity while releasing metal ions from the A component and subsequently crosslinking the B component. Therefore, the flow of the B component can be utilized to enhance the dispersibility of the A component in the B component, resulting in a crosslinked product with highly uniform crosslinking points. This, combined with the effect of the C component, is highly effective in improving the abrasion resistance of the crosslinked polymer material. Furthermore, unintended release of metal ions from the A component and subsequent crosslinking of the B component are unlikely to occur during the preparation of the crosslinkable polymer composition.

[0024] [7] In any one of the above aspects [1] to [6], the component A may be a metal complex containing a ligand having the structure of the following formula (2): Here, R ４ and R ５ each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R ６ represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. ４ , R ５ , R ６ The present invention also includes a case where at least two of the groups are connected to each other by a ring structure.

[0025] The β-diketonato ligand represented by formula (2) is a bidentate ligand, and has a superior effect of stabilizing metal ions compared to monodentate ligands and ligands that form a crosslinked coordination structure. Therefore, liberation of metal ions from component A is suppressed during preparation of the crosslinkable polymer composition or before use of the crosslinkable polymer composition, and particularly high storage stability is obtained.

[0026] [8] In any one of the above aspects [1] to [7], the metal ions liberated from the component A may be ions of at least one of alkaline earth metals, aluminum, zinc, titanium, and zirconium. The ions of the above metals all have a valence of 2 or more, and are likely to form a stable crosslinked structure between the polymer chains of the component B. Furthermore, the ions of the above metals belong to the hard acid group according to the HSAB rule and have a high tendency to ionize, forming a stable bond with the substituent of the component B. For these reasons, they are suitable as metals for forming a crosslinked body.

[0027] [9] In any one of the above aspects [1] to [8], the substituent of the B component may be at least one of a carboxylic acid group, an acid anhydride group, a phosphate group, and an acrylic acid group. These substituents are likely to form ionic bonds with metal ions released from the A component. Furthermore, because the B component is an acidic group with relatively low polarity, it is less likely to undergo phase separation in the main chain or side chain of the B component, and a highly spatially uniform crosslinked structure can be formed. This, combined with the effect of the C component, provides a significant effect in improving the abrasion resistance of the crosslinked polymer material.

[0028]

[10] In any one of the above aspects [1] to [9], the substituent of the component B may be bonded to the main chain via an alkyl or alkylene group having one or more carbon atoms. This increases the degree of freedom of thermal movement at the crosslinked sites, making it easier for the crosslinked points to move when heated, resulting in particularly high remoldability.

[0029]

[11] In any one of the above aspects [1] to

[10] , the component B may have a glass transition temperature of 10°C or lower. This makes it easier to obtain a crosslinked polymer material obtained through a crosslinking reaction that has high mechanical strength, such as high abrasion resistance, while also exhibiting high flexibility. A polymer material with excellent mechanical strength and flexibility can be suitably used, for example, to form an insulating coating for an insulated electric wire. It is more preferable that the glass transition temperature of the component B is 0°C or lower.

[0030]

[12] In any one of the above aspects [1] to

[11] , it is preferable that the component B does not contain an electron-withdrawing group in the main chain. This prevents the side chain substituent from being prevented from forming an ionic bond with the metal ion derived from the component A due to competition with the electron-withdrawing group in the main chain. The substituent in the main chain is unlikely to form a stable crosslinked structure with the metal ion due to steric hindrance. Even if a crosslinked structure is formed, the degree of freedom of movement of the crosslinked site is reduced, making it difficult to obtain high remoldability in the crosslinked product.

[0031]

[13] In any one of the above aspects [1] to

[12] , the main chain of the component B may be an olefin-based polymer or a styrene-based polymer. This allows the high mechanical strength provided by the main chain to be easily exhibited as a characteristic of the crosslinked product. Furthermore, the main chain is less likely to affect the formation of crosslinking points in the side chains of the component B and the movement of those crosslinking points. Therefore, the high heat resistance, abrasion resistance, and remoldability provided by these phenomena in the side chains are effectively exhibited as characteristics of the entire material.

[0032]

[14] In any one of the above aspects [1] to

[13] , the crosslinkable polymer composition may contain 0.1 to 30 parts by mass of the A component, where the total of the A component, the B component, and the C component is 100 parts by mass. By containing a sufficient amount of the A component, the crosslink density is increased, and the crosslinkable polymer composition has excellent crosslinkability. On the other hand, the influence of containing a large amount of the A component in the material before and after crosslinking can be easily avoided.

[0033]

[15] In any one of the above aspects [1] to

[14] , the crosslinkable polymer composition may contain 0.5 to 20 parts by mass of the C component, with the total of the A component, the B component, and the C component being 100 parts by mass. By including a sufficient amount of the C component, the uniformity of the crosslinked sites in the crosslinked product and the resulting abrasion resistance can be improved. On the other hand, by avoiding excessive inclusion of the C component, the crosslinked material is less likely to suffer from phenomena such as a decrease in physical properties such as material strength and low-temperature characteristics, or an excessive increase in elastic modulus, due to the formation of aggregates derived from the C component or an insufficient B content.

[0034]

[16] A crosslinked polymer material according to the present disclosure is composed of a material obtained by crosslinking the crosslinkable polymer composition according to any one of [1] to

[15] above, and includes a crosslinked body formed by crosslinking the B component with a metal ion liberated from the A component, and the C component. The crosslinked body formed by crosslinking the B component via the metal ion liberated from the A component has a crosslinking point at the position of the electron-withdrawing substituent introduced into the side chain of the B component, so that the crosslinked polymer material has both high heat resistance and reshapeability by heating. Furthermore, a decrease in flexibility due to crosslinking is unlikely to occur. In the crosslinked polymer material, most of the C component is present without being incorporated into the crosslinked structure, but due to the contribution of the C component, the crosslinked structure is formed with high uniformity throughout the crosslinked polymer material, resulting in the crosslinked polymer material having high wear resistance.

[0035]

[17] In the above aspect

[16] , the tensile modulus of the crosslinked polymer material is preferably less than 20 MPa. This results in a crosslinked polymer with high flexibility. However, a crosslinked polymer material with a tensile modulus of more than 20 MPa is also preferred in that it has particularly excellent mechanical strength, such as abrasion resistance.

[0036]

[18] An insulated wire according to the present disclosure includes a conductor and an insulating coating made of the cross-linked polymer material described in

[16] or

[17] above, covering the outer periphery of the conductor. Because the insulating coating is made of the cross-linked polymer material described in the present disclosure, this insulated wire exhibits high heat resistance and is less likely to undergo irreversible deformation even when the conductor generates heat due to current flow. Meanwhile, by heating the insulating coating to a sufficient temperature, the insulating coating can be re-fluidized and reshaped, allowing for a change in shape. For example, when the conductor is deformed, the insulating coating can be easily deformed to conform to the shape of the conductor. Furthermore, because the cross-linked polymer material contains component C, the improved uniformity of cross-linked portions due to component C can be utilized to achieve high abrasion resistance in the insulating coating formed by heat molding such as extrusion molding and in the insulating coating after heat reshaping. Furthermore, since the flexibility of the material is less likely to decrease due to crosslinking, the insulating coating can be made highly flexible, and even if the electric wire is formed to be thick, it can be easily routed, which requires bending.

[0037]

[19] In the aspect

[18] above, the conductor may be formed by twisting together a plurality of strands of wire, and the insulated wire may have a flattened portion where the cross section of the conductor perpendicular to the axial direction is flattened. A wire having a flattened portion is required from the viewpoint of space saving, etc. The flattened portion can be easily formed by applying a compressive force to a circular cross-section of a normal insulated wire by heating the insulating coating, taking advantage of the reshapeability of the insulating coating. Conversely, by applying a force to a wire with a flattened portion while heating the insulating coating in a direction that eliminates the flattened shape, the insulated wire can be deformed to a state having a different cross-sectional shape, such as a circular cross-section. In this way, by using an insulated wire having a conductor formed by twisting together a plurality of strands of wire and that is easily deformed by applying a force, and an insulating coating that can be reversibly transformed into a reshapeable state by heating, deformation between a state with a low degree of flatness, such as a circular cross-section, and a flat state can be easily performed in both directions. For example, a variety of insulated wires can be obtained by using a common insulated wire and deforming necessary portions into a required shape, such as a flat shape, depending on the installation location and application.

[0038]

[20] A wire harness according to the present disclosure includes the insulated wire according to the above

[18] or

[19] . As described above, the insulated wire according to the present disclosure has an insulating coating that is excellent in heat resistance, formability during initial molding and remolding, and abrasion resistance, and therefore these properties can be utilized in the wire harness.

[0039] [Details of Embodiments of the Present Disclosure] The crosslinkable polymer composition, crosslinked polymer material, insulated wire, and wire harness according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these embodiments.

[0040] [1] Crosslinkable polymer composition and crosslinkable polymer material A crosslinkable polymer composition according to an embodiment of the present disclosure includes a component A from which metal ions are liberated by heat, a component B having an electron-withdrawing substituent on its side chain that is capable of forming an ionic bond with the metal ion liberated from the component A, and a component C composed of a secondary or tertiary amine represented by the following formula (1): Here, R １ is a hydrogen atom or a hydrocarbon group having 30 or less carbon atoms, R ２ is a hydrocarbon group having 30 or less carbon atoms, R ３ is a hydrocarbon group having 13 to 30 carbon atoms.

[0041] The crosslinkable polymer composition according to this embodiment is heated to form a crosslinked body in which component B is crosslinked by metal ions liberated from component A, thereby constituting a crosslinked polymer material according to an embodiment of the present disclosure. The crosslinked polymer material contains this crosslinked body and component C. In this specification, the crosslinkable polymer composition basically refers to a state in which the formation of a crosslinked body has not progressed, but materials in which crosslinking has progressed to a certain extent when subjected to heat kneading, extrusion molding, or other heat molding are also included in the crosslinkable polymer composition.

[0042] (1) Characteristics of the Crosslinkable Polymer Composition and Crosslinked Polymer Material Before describing each component of the crosslinkable polymer composition in detail, we will first describe the characteristics of the crosslinkable polymer composition and crosslinked polymer material. The crosslinkable polymer composition according to this embodiment contains component A, which liberates metal ions when heated, component B, which has a substituent capable of forming an ionic bond with the metal ion, and component C, which is a secondary or tertiary amine having the structure of formula (1). When a crosslinkable polymer composition containing these components is heated, metal ions are liberated from component A. The liberated metal ions then form ionic bonds with the substituents of component B, and the organic polymer chains of component B are crosslinked via these ionic bonds. Meanwhile, in the crosslinked polymer material, most of component C is not incorporated into the crosslinked product, but coexists with the crosslinked product while maintaining the molecular structure represented by formula (1).

[0043] Component A liberates metal ions upon exposure to heat, but until the temperature at which component A liberates metal ions due to decomposition or phase transition is reached, the liberation of metal ions from component A does not occur, and crosslinking of the organic polymer in component B due to the formation of ionic bonds does not proceed. Therefore, the crosslinkable polymer composition according to this embodiment is in a relatively fluid state at low temperatures at which the liberation of metal ions from component A and the resulting crosslinking of component B do not occur, and can be easily molded into a desired shape by extrusion molding or the like. After molding the crosslinkable polymer composition into a desired shape, a crosslinked body can be formed by heating to liberate metal ions from component A and crosslink component B. Alternatively, the crosslinked body can be formed into a desired shape by extrusion molding or the like after or while forming the crosslinked body by heating.

[0044] The crosslinked body has improved heat resistance compared to the state before crosslinking due to the crosslinking of adjacent polymer chains of component B. In the crosslinked body, the organic polymer chains of component B are crosslinked via ionic bonds, and the bonding force is stronger than van der Waals forces, effectively improving the heat resistance and mechanical toughness of the crosslinked body. On the other hand, compared to when a crosslinked structure is formed by covalent bonds, a decrease in flexibility due to crosslinking is less likely to occur. In particular, when a highly flexible organic polymer is used as component B, the polymer material after crosslinking also has high flexibility.

[0045] Furthermore, in the crosslinkable polymer composition according to this embodiment, the crosslinked structure between the polymer chains of component B is formed by a reversible ionic bond with a metal ion, rather than an irreversible covalent bond formed in the case of electron beam crosslinking or silane crosslinking, and therefore the crosslinked polymer material thus formed is remoldable. In other words, by heating a crosslinked polymer material once formed through crosslinking, the crosslinked polymer material regains its fluidity and can be molded into a shape different from that before heating by application of an external force, etc.

[0046] The reshapeability of crosslinked polymer materials can be explained by the following mechanism. When a crosslinked body in which polymer chains of component B are crosslinked with metal ions is not heated and is at or near room temperature, the crosslinking points of metal ions are localized at certain positions within the chains of component B, as shown in Figure 1A. However, when the crosslinked body is heated, the molecular motion of component B becomes active due to heat, and as shown in Figure 1B, active thermal motion occurs at the crosslinked sites where the substituents of component B and the metal ions form ionic bonds, as well as in their vicinity. When the crosslinked body is heated to a higher temperature, the molecular motion of component B is further activated, allowing the crosslinking points mediated by the metal ions to migrate to nearby sites (the positions of other substituents), resulting in delocalization of the crosslinking points. Delocalization of the crosslinking points results in a state in which multiple substituents within the same molecular chain of component B are simultaneously coordinated to a single metal ion (multidentate formation), as shown in Figure 1C. This activation of thermal motion in component B and the subsequent migration of the crosslinking points make the crosslinked body flowable. In these states, the crosslinked polymer material can be reshaped by applying an appropriate external force to the material. The activation of thermal motion at crosslinking sites and the delocalization of crosslinking sites are reversible phenomena; cooling the reshaped crosslinked polymer material returns it to a localized state of crosslinking sites, returning it to a thermally stable crosslinked state. Repeated heating and cooling also allows the crosslinked polymer material to be repeatedly reshaped. The activation of thermal motion at crosslinking sites and the delocalization of crosslinking sites due to heating can be confirmed, for example, by infrared absorption spectroscopy. Typically, the activation of thermal motion at crosslinking sites appears in the spectrum as a broadening of the absorption peak of the substituents forming the crosslinked structure, and the delocalization of crosslinking sites appears in the spectrum as the growth of a new peak corresponding to multidentate crosslinking.

[0047] Furthermore, in the crosslinkable polymer composition according to this embodiment, the substituent capable of forming an ionic bond with a metal ion is contained in the side chain of component B, rather than in the polymer main chain. This allows for high freedom of movement at the crosslinked sites when a crosslinked structure is formed via the metal ion. Therefore, in the crosslinked product, thermal movement at the crosslinked sites and migration of the crosslinking points are particularly likely to occur. This allows the crosslinked polymer material to exhibit high remoldability when heated.

[0048] As described above, the crosslinkable polymer composition according to this embodiment contains component A, which liberates metal ions upon heating, and component B, which has a side chain containing a substituent capable of forming an ionic bond with the metal ion, and thereby provides a crosslinked polymer material that has high heat resistance and is also remoldable upon heating. Because of these properties, the crosslinked polymer material according to this embodiment can be suitably used to construct components that require high heat resistance and are advantageously remoldable, such as insulating coatings for insulated electric wires. As an indicator that the heat resistance-improving effect of crosslinking is fully exhibited in a crosslinked polymer material, the flow initiation temperature of the crosslinked polymer material is preferably at least 5°C, and even at least 10°C, higher than the flow initiation temperature of component B alone.

[0049] As described above, in the crosslinkable polymer composition according to this embodiment, components A and B form an ionic crosslinked structure, resulting in a crosslinked polymer material that has high heat resistance and remoldability and is less susceptible to a decrease in flexibility due to crosslinking. Furthermore, since the crosslinkable polymer composition contains component C in addition to components A and B, the crosslinked polymer material obtained through crosslinking has even greater mechanical strength, such as wear resistance. The reasons for this are as follows.

[0050] When the crosslinkable polymer composition does not contain component C, a crosslinking reaction due to the formation of ionic bonds between metal ions liberated from component A and the substituents of component B may occur at a high rate. This may result in the crosslinking reaction proceeding locally, resulting in the formation of aggregates. In this case, the crosslinking reaction does not occur uniformly throughout the material, making it difficult to increase the degree of crosslinking of the entire material. The crosslinked structure between polymer chains acts to enhance the mechanical strength, such as the abrasion resistance, of the polymer material. However, if the crosslinked structure is not formed uniformly throughout the material as described above and the degree of crosslinking of the entire material is low, the crosslinked polymer material will not be able to fully achieve the effect of improving the mechanical strength due to the crosslinked structure, and the abrasion resistance will not be sufficiently improved.

[0051] On the other hand, when a crosslinkable polymer composition contains a C component consisting of a secondary or tertiary amine, at least a portion of the C component becomes a secondary or tertiary ammonium cation upon heating. The generated ammonium cation forms an ionic bond with an electron-withdrawing substituent on the side chain of the B component. The formation of an ionic bond between this ammonium cation and the B component competes with the reaction in which a metal ion liberated from the A component forms an ionic bond with the B component to form a crosslink, thereby at least partially inhibiting the crosslinking reaction between the B component polymer chains via the metal ion. As a result, the rate of progress of the crosslinking reaction decreases. The decrease in the rate of progress of the crosslinking reaction can be confirmed, for example, by the fact that, in differential scanning calorimetry (DSC), the exothermic peak corresponding to the progress of the crosslinking reaction becomes gentler with the addition of the C component.

[0052] In this way, when the rate of crosslinking reaction of the polymer chains of component B by the metal derived from component A is suppressed, the situation in which the crosslinking reaction proceeds locally at a high rate and forms aggregates, as occurs when component C is not added, is less likely to occur. This allows the crosslinking reaction to proceed uniformly throughout the material, and the degree of crosslinking also increases. Furthermore, the slower rate of the crosslinking reaction also reduces the likelihood of a sudden increase in viscosity due to crosslinking, allowing the material to be heated and kneaded for a longer period of time. This also contributes to an increase in the degree of crosslinking. By increasing the uniformity of the crosslinking reaction and the degree of crosslinking, the resulting crosslinked polymer material has a highly uniformly distributed crosslinked structure and a high density. This results in a crosslinked polymer material with excellent mechanical strength, including wear resistance.

[0053] An increase in crosslink density can be evaluated as an increase in the gel fraction of the crosslinked polymer material. For example, the gel fraction of the crosslinked polymer material is preferably 80% or more, and even 85% or more. The upper limit of the gel fraction is not particularly specified, but is generally 95% or less. As will be described in the Examples below, the gel fraction can be evaluated by immersing the polymer material in a solvent such as xylene to extract non-crosslinked components, and then measuring the ratio of the mass after immersion to the mass before immersion.

[0054] The formation of ammonium cations from the amine component C proceeds easily when the crosslinkable polymer composition is heated, as component C bonds with protons liberated from the substituent of component B or protons generated during decomposition of component A, and can occur at a lower temperature than the liberation of metal ions from component A. Furthermore, to form a crosslinked structure, one metal ion must bond with substituents at two locations, whereas the formation of a crosslinked structure is hindered by the formation of an ionic bond between the generated ammonium cation and only one substituent of component B. Therefore, the formation of an ionic bond between the ammonium cation and the substituent of component B proceeds at a lower temperature than the crosslinking reaction caused by the metal ion liberated from component A and at a higher rate than the crosslinking reaction, and is therefore effective in suppressing the rate of the crosslinking reaction by competing with it. On the other hand, compared to metal ions, ammonium cations are softer bases and are less likely to form strong bonds with the substituents of component B, and are also less likely to bond with multiple substituents in component B to form a crosslinked structure. Therefore, even if ammonium cations form ionic bonds with the substituents of component B, as heating and kneading continues, the ammonium cations are gradually replaced by metal ions derived from component A, and crosslinked structures are formed between the polymer chains of component B. In the crosslinked polymer material finally obtained, the polymer chains of component B are crosslinked by the metal ions derived from component A, and a structure in which the polymer chains of component B are crosslinked via ammonium cations derived from component C is less likely to be formed. Except for a portion of component C remaining in the form of ammonium cations ionically bonded to the substituents of component B, component C reverts to an amine state and is less likely to be incorporated into the crosslinked structure.

[0055] As explained above, the inclusion of component C in the crosslinkable polymer composition results in a crosslinked polymer material obtained by crosslinking component B with metal ions derived from component A, which exhibits excellent mechanical strength, such as wear resistance. High mechanical strength is required for polymer materials used in a variety of applications. For example, the crosslinked polymer material can be suitably used as a component constituting an insulating coating for an insulated electric wire. In insulating coatings, high mechanical strength can reduce the effects of damage caused by contact with external objects, etc. Furthermore, as mentioned above, the crosslinked product formed from components A and B is unlikely to experience a decrease in flexibility due to the crosslinking formed by ionic bonds, and the addition of component C does not significantly impair the flexibility of the crosslinked product. In particular, if a material with sufficient flexibility is used as component B, the crosslinked polymer material will also exhibit high flexibility. Crosslinked products using a highly flexible polymer material as component B tend to have low wear resistance, but the addition of component C improves the wear resistance of the crosslinked polymer material as a whole, achieving both high flexibility and high wear resistance. By using a cross-linked polymer material that has both high flexibility and high abrasion resistance to form an insulating coating for an insulated wire, it is possible to highly ensure the bending flexibility of the insulated wire while suppressing the effects of damage.

[0056] Furthermore, in the crosslinked polymer material according to this embodiment, the crosslinked polymer formed from component A and component B preferably has a flow initiation temperature in the range of 190°C or higher and 300°C or lower. When the flow initiation temperature of the crosslinked polymer is 190°C or higher, the crosslinked polymer material is less likely to experience increased fluidity and the associated irreversible deformation at temperatures below 190°C, resulting in a crosslinked polymer material with high heat resistance. Here, a heat resistance temperature of 190°C is generally desired for insulating coatings for automotive insulated wires, and the crosslinked polymer material according to this embodiment can be suitably used to form insulating coatings for automotive insulated wires, as described in detail below. From the viewpoint of effectively enhancing the heat resistance of the crosslinked polymer material, the flow initiation temperature of the crosslinked polymer is preferably 200°C or higher, and even more preferably 220°C or higher. On the other hand, when the flow initiation temperature of the crosslinked polymer is kept below 300°C, the crosslinked polymer material can be remolded by heating it to 300°C, making remolding easy. From the viewpoint of effectively enhancing remoldability, the flow initiation temperature of the crosslinked body is preferably 280° C. or lower, and more preferably 250° C. or lower. The flow initiation temperature of the crosslinked body and of component B, which will be described later, refers to the temperature at which a solid material begins to exhibit fluidity when heated, and can be measured as the temperature at which an indenter can penetrate a sheet-like material, as shown in the examples below. Alternatively, the melting point or flow point of the material (the lower of the two, if both are present) can be considered to be the flow initiation temperature.

[0057] The crosslinked polymer material according to this embodiment can have a wide range of tensile modulus depending on the tensile modulus of the polymer material used as component B, and the specific tensile modulus is not particularly limited. However, if particularly high flexibility is desired, the tensile modulus of the crosslinked polymer material is preferably 80 MPa or less. More preferably, the tensile modulus is 50 MPa or less, and even 20 MPa or less. Although the lower limit of the tensile modulus of the crosslinked polymer material is not particularly specified, from the viewpoint of ensuring sufficient mechanical strength, it is preferably 5 MPa or more, and even 10 MPa or more. On the other hand, if particularly high mechanical strength, including abrasion resistance, is desired in the crosslinked polymer material, the tensile modulus may be higher than 80 MPa. In particular, if the tensile modulus of the crosslinked polymer material is 200 MPa or more, or even 500 MPa or more, particularly high mechanical strength can be obtained. Even in this case, from the viewpoint of ensuring flexibility, it is preferable to limit the tensile modulus to 1600 MPa or less. The tensile modulus can be measured, for example, by a tensile test in accordance with JIS K 7161.

[0058] As described above, the crosslinkable polymer composition according to this embodiment undergoes crosslinking to become a crosslinked polymer material that has high heat resistance, remoldability, and high mechanical strength. Furthermore, even after crosslinking, flexibility is less likely to decrease. From the perspective of particularly enhancing these properties, appropriate specific types and structures may be selected for each of the A, B, and C components. Furthermore, the mixing ratio of each component also affects these properties. The preferred structures and properties of each component are described below in order.

[0059] (2) Component A Component A is a component that releases metal ions when heated. "When heated" refers to heating, and is assumed to be at a temperature higher than room temperature. "The release of metal ions" refers to the release of metal ions from component A when component A decomposes or undergoes a phase transition. The metal ions released from component A cause crosslinking of component B.

[0060] Component A preferably has a decomposition point or phase transition point of 50°C or higher. This makes it easier to suppress the release of metal ions from component A during preparation of the crosslinkable polymer composition or before use (before crosslinking) of the crosslinkable polymer composition, and inhibits the progress of crosslinking of component B, resulting in excellent storage stability of the crosslinkable polymer composition. In other words, when preparing a crosslinkable polymer composition by mixing components A and B at low temperatures, such as below 50°C, or when storing the prepared crosslinkable polymer composition, unintended release of metal ions from component A and the accompanying crosslinking of component B are unlikely to occur, leading to quality degradation of the crosslinkable polymer composition. When component A has a decomposition point or phase transition point of 60°C or higher, or even 70°C or higher, the effect of improving storage stability is further enhanced.

[0061] On the other hand, it is preferable that component A has a decomposition point or phase transition point of 300°C or less. This makes it difficult for component B to degrade at a temperature lower than that at which metal ions are liberated from component A, and makes it easier to crosslink unaltered component B with metal ions. Furthermore, decomposition or phase transition of component A at a moderate temperature makes it easy to liberate metal ions from component A, resulting in a crosslinkable polymer composition with an excellent crosslinking rate. From these perspectives, it is more preferable that component A has a decomposition point or phase transition point of 200°C or less, further 150°C or less, or even 120°C or less.

[0062] Furthermore, it is preferable that component A has a decomposition point or phase transition point at a temperature equal to or higher than the flow initiation temperature of component B, which will be described later. Then, at the temperature at which component A liberates metal ions, crosslinking of component B can proceed by metal ions liberated from component A, while component B has already acquired fluidity. Therefore, by utilizing the flow of component B, crosslinking can proceed while metal ions are well dispersed in component B, making it easier to obtain a crosslinked polymer material with a highly uniform structure in which crosslinking points by metal ions are spatially distributed with high uniformity. This enhances the effect of improving mechanical strength, such as abrasion resistance, through crosslinking. Furthermore, during the preparation of a crosslinkable polymer composition, unintentional liberation of metal ions from component A and the accompanying crosslinking of component B are unlikely to occur. More preferably, component A has a decomposition point or phase transition point at a temperature higher than the flow initiation temperature of component B, and even more preferably, component A has a decomposition point or phase transition point at a temperature 10°C or higher than the flow initiation temperature of component B. The decomposition point or phase transition point of component A is expressed as the baseline change initiation temperature by DSC. Furthermore, the phase transition point does not include a melting point, and the phase transition does not include melting. When component A has both a phase transition point and a decomposition point, or when it has multiple phase transition points, the lower of these (the lowest) is treated as the "decomposition point or phase transition point."

[0063] The metal species of the metal ions liberated from component A is not particularly limited, but alkaline earth metals, aluminum, zinc, titanium, zirconium, etc. can be suitably used. The metal ions liberated from component A are preferably ions of at least one of these metals. The ions of these metals have a valence of 2 or more, and form ionic bonds with the substituents of component B, making it easy to form a stable crosslinked structure between the polymer chains of component B. Furthermore, the ions of the metals listed above belong to hard acids according to the HSAB rule and are metals with a relatively high ionization tendency, so they form stable bonds with the substituents of component B and are suitable as metals for constituting a crosslinked body.

[0064] Furthermore, when a member that comes into contact with a metal member is constructed using the crosslinkable polymer composition according to this embodiment, if the metal species contained in the crosslinkable polymer composition is the same as the metal species that is the main component of the metal member, the influence of the presence of the metal member on the formation and stable maintenance of a crosslinked structure at the interface between the metal member and the polymer material can be easily minimized. For example, when an insulating coating that covers an aluminum or aluminum alloy wire conductor in an insulated electric wire is formed using the crosslinkable polymer composition according to this embodiment, the metal ions liberated from Component A can be aluminum.

[0065] The metal ions liberated from component A are not limited to the metal species listed above as preferred, but may be any metal ion capable of crosslinking component B by forming an ionic bond with the substituent of component B, and more preferably capable of providing a crosslinked product having a flow initiation temperature of 190°C or higher and 300°C or lower. However, transition metals such as iron, nickel, and copper tend to provide crosslinked products with a flow initiation temperature higher than the above range. This is thought to be because when a crosslinked product is formed using ions of metals that have a wide range of oxidation states or a low ionization tendency, such as transition metals, the crosslinking points tend not to migrate upon heating (see Figure 1C). Furthermore, the metal ions liberated from component A may be not only monoatomic ions of the metal, but also polyatomic ions (metal-containing ions) formed by bonding a metal atom to another atom. However, monoatomic ions of the metal are preferred from the viewpoint of forming a stable ionic bond with the substituent of component B.

[0066] Component A may be any chemical species as long as it liberates metal ions by heat, but a suitable chemical species is a metal complex. A metal complex is composed of a central metal ion to which a ligand having an unshared electron pair is coordinately bonded. When a metal complex is used, the ligand has an excellent effect of stabilizing the metal ion, and liberation of metal ions from component A is suppressed during preparation of the crosslinkable polymer composition or before use of the crosslinkable polymer composition, and when crosslinking the crosslinkable polymer composition, metal ions are easily liberated from component A by heat.

[0067] Ligands constituting the metal complex include monodentate ligands with one coordination site and multidentate ligands with two or more coordination sites. Due to the chelate effect, metal complexes formed with multidentate ligands are more stable than metal complexes formed with monodentate ligands or metal complexes formed with ligands having a bridged coordination structure, such as alkoxide ligands. Therefore, it is preferable that component A is a metal complex containing a multidentate ligand. Coordination with a multidentate ligand is more effective at stabilizing metal ions than coordination with a monodentate ligand or coordination with a ligand having a bridged coordination structure, and thus, release of metal ions from component A is more effectively suppressed during preparation of the crosslinkable polymer composition or before use of the crosslinkable polymer composition.

[0068] Among polydentate ligands, bidentate β-diketonato ligands (1,3-diketonato ligands) can be preferably used. β-diketonato ligands are particularly effective in stabilizing metal ions. Furthermore, metal complexes having β-diketonato ligands are easily dispersed in organic polymers, making them suitable for dispersing component A in component B and forming highly uniform crosslinking points. β-diketonato ligands are represented by the following general formula (2):

[0069] In formula (2), R ４ , R ５ each independently represents a hydrocarbon group; R ６ represents a hydrogen atom or a hydrocarbon group. ４ , R ５ , R ６ The ligand may have a structure of formula (2) due to a resonance structure.

[0070] In formula (2), R ４ , R ５ , R ６ R may be an aliphatic hydrocarbon group or a hydrocarbon group containing an aromatic ring. It may also contain a heteroatom such as an oxygen atom. ４ , R ５ , R ６Examples of the hydrocarbon group constituting R include an alkyl group, an alkoxy group, an aromatic group, and a condensed aromatic group. ４ , R ５ , R ６ The number of carbon atoms of each is not particularly limited, but is preferably 1 or more and 8 or less.

[0071] Specific examples of the β-diketonato ligand include an acetylacetonato ligand (acac), a 2,2,6,6-tetramethyl-3,5-heptanedionato ligand (dpm), a 3-methyl-2,4-pentanedionato ligand, a 3-ethyl-2,4-pentanedionato ligand, a 3,5-heptanedionato ligand, a 2,6-dimethyl-3,5-heptanedionato ligand, and a 1,3-diphenyl-1,3-propanedionato ligand. Among these, from the viewpoint of structural simplicity and the like, the ligand in which R ４ and R ５ is a methyl group, R ６ Particularly preferred is an acetylacetonato ligand in which is a hydrogen atom.

[0072] In the crosslinkable polymer composition, the content of component A is preferably 0.1 parts by mass or more, relative to 100 parts by mass of the total of components A, B, and C. Thus, by including a sufficiently large amount of component A relative to component B, the crosslink density in the crosslinked product is increased, thereby exhibiting a high effect in improving heat resistance and abrasion resistance. From the viewpoint of enhancing the effect of improving heat resistance and abrasion resistance, the content of component A is preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more, relative to the 100 parts by mass. Meanwhile, the content of component A is preferably 30 parts by mass or less, relative to the 100 parts by mass. This makes it easier to avoid the effects of including a large amount of component A, such as separation or precipitation of component A before crosslinking and embrittlement of the polymer material after crosslinking. Furthermore, by not including an excess of component A in the crosslinkable polymer composition, the high mechanical strength of component B is more easily exhibited as a property of the entire crosslinked polymer material. From the viewpoint of enhancing these effects, the content of component A is more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass.

[0073] (3) Component B Component B is a component composed of an organic polymer having a side chain, and contains an electron-withdrawing substituent in the side chain that can form an ionic bond with a metal ion released from Component A. The substituent does not necessarily have to be electron-withdrawing to be able to form an ionic bond with a metal ion released from Component A, but being electron-withdrawing allows for the formation of a stable ionic bond with the metal ion. Therefore, when Component B is crosslinked with a metal ion in the crosslinkable polymer composition, a stable crosslinked structure is formed, and the crosslinked product is likely to exhibit high heat resistance.

[0074] Suitable examples of electron-withdrawing substituents capable of forming ionic bonds with metal ions include acidic groups other than hydroxyl groups, such as carboxylic acid groups, acid anhydride groups, phosphate groups, and acrylic acid groups. The substituents may be one type or two or more types, but at least one of the substituents listed above is preferred. In particular, maleic acid groups and acrylic acid groups are suitable. Acid anhydride groups such as maleic anhydride groups are also suitable. The substituents listed above are advantageous in that they easily form ionic bonds with metal ions liberated from component A. Furthermore, since all of the substituents listed above are acidic groups with relatively low polarity, they are less likely to undergo phase separation with respect to the main chain or side chain of component B. Therefore, a highly uniform crosslinked structure can be formed within the structure of component B. As a result, the crosslinking can significantly improve mechanical strength, such as abrasion resistance. For example, a sulfonic acid group is also an electron-withdrawing substituent that easily forms an ionic bond with a metal ion, but because it has high polarity, it is prone to phase separation, and therefore cannot be used as a substituent for component B as preferably as the substituents listed above as being suitable.

[0075] As explained above, in component B, the substituent that forms an ionic bond with the metal ion is contained in the side chain, not the polymer main chain, thereby maintaining a high degree of freedom of movement at the crosslinked site when a crosslinked structure is formed. As a result, the crosslinked polymer material has high reshapeability. The structure and length of the side chain are not particularly limited, but from the viewpoint of enhancing their effects, it is preferable that the substituent be bonded to the main chain via an alkyl or alkylene group having one or more carbon atoms. Alternatively, the substituent may be bonded to the main chain via a heteroatom such as an oxygen atom. The substituent may be introduced at the end or the middle of the side chain, but from the viewpoint of effectively increasing the degree of freedom of movement at the crosslinked site, it is preferable that it be introduced at the end. There is no particular upper limit on the number of carbon atoms in the side chain, but from the viewpoint of minimizing the impact on the physical properties of the main chain, it is preferable that the number of carbon atoms connecting the main chain and the substituent be four or less. When the substituent is a carboxylic acid group or a phosphate group, particularly preferred side chain structures are represented by the following formulas (3) and (4), respectively.

[0076] Here, R ７ is the main chain, R ８ is an oxygen atom or an alkyl or alkylene group having one or more carbon atoms, R ９ is also an alkyl group or alkylene group having one or more carbon atoms. ８ or R ９ A plurality of electron-withdrawing substituents may be bonded to the main chain via an anhydride.

[0077] In component B, the electron-withdrawing substituent may be contained in either the main chain or the side chain, as long as it is contained in the side chain. However, it is preferable that the main chain does not contain an electron-withdrawing group. This is because the presence of an electron-withdrawing group in the main chain may prevent the electron-withdrawing group in the side chain from forming a crosslinked structure through an ionic bond with a metal ion. Because the electron-withdrawing group in the main chain is susceptible to significant steric hindrance, it is difficult to effectively contribute to crosslinking through the formation of an ionic bond with a metal ion, and the effect of improving heat resistance through crosslinking is poor. Furthermore, even if a crosslinked structure is formed at the electron-withdrawing group in the main chain, the degree of freedom of movement at the crosslinked site is reduced, making it difficult to achieve high remoldability. The effect of inhibiting the progress of the crosslinking reaction by component C is also difficult to achieve. Examples of electron-withdrawing groups that should not be contained in the main chain of component B include carboxy groups and halogen atoms when the main chain is composed of a copolymer of (meth)acrylic acid. Furthermore, it is preferable that Component B does not contain atoms capable of forming coordinate bonds with metal ions, such as nitrogen atoms or sulfur atoms, in its side chains while leaving unshared electron pairs capable of forming coordinate bonds, because if such atoms form coordinate bonds with metal ions released from Component A, the ionic bond strength between the electron-withdrawing functional group and the metal ions may be reduced.

[0078] In Component B, the content of the substituent contained in the side chain is not particularly limited, but from the viewpoint of ensuring physical properties by crosslinking, it is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and even more preferably 0.2% by mass or more and 3% by mass or less, relative to the total mass of Component B. The content of the above-mentioned substituent in Component B can be determined by comparing the magnitude of the peak characteristic of the substituent in the infrared absorption spectrum with the magnitude of the spectral peak of a material whose content is known.

[0079] The organic polymer of Component B is an organic polymer such as a resin, rubber, or elastomer. Component B is preferably composed of a thermoplastic resin from the viewpoint of moldability during hot molding, such as extrusion molding. In particular, from the viewpoint of ensuring high moldability, flexibility, and mechanical strength, an olefin-based polymer or a styrene-based polymer can be suitably used as the main chain constituting Component B. Alternatively, an acrylic polymer can be used. Specific examples of polymers constituting the main chain of Component B include polypropylene, polyethylene, polybutene, polybutadiene, polypentene, polyhexene, polymethylpentene, polyoctene, polymethylmethacrylate, copolymers containing monomers constituting these polymers, and styrene-based thermoplastic elastomers such as styrene-ethylene-butylene-styrene block copolymer (SEBS). Of the listed polymers, polypropylene, polyethylene, various ethylene-α-olefin copolymers, styrene-based thermoplastic elastomers, and other ethylene-based copolymers are particularly suitable from the viewpoints of availability and chemical resistance. Component B may be used alone or in combination of two or more types. To obtain particularly high mechanical strength, it is preferable to use, as the main chain, one of the above-listed materials that provides a high tensile modulus of elasticity, such as polypropylene, whereas to obtain particularly high flexibility, it is preferable to use, as the main chain, one of the above-listed materials that provides a low tensile modulus of elasticity, such as an ethylene-based copolymer such as ethylene-methyl acrylate copolymer (EMA) or ethylene-vinyl acetate copolymer (EVA), a styrene-based thermoplastic elastomer, or low-density polyethylene.

[0080] The polymer species constituting the main chain of component B are not limited to those listed above, but as mentioned above, it is preferable that the main chain does not contain an electron-withdrawing group, and from the viewpoint of ensuring thermoplasticity, flexibility, and chemical resistance, it is also preferable that component B does not contain an ether bond or a cyclic structure in the main chain. In other words, it is preferable that the main chain of component B has a skeleton in which carbon atoms are continuous in a linear or branched chain.

[0081] Component B is preferably composed of an organic polymer with a low glass transition temperature. Specifically, the glass transition temperature is preferably 10°C or lower. This makes it easier to achieve both high flexibility and high mechanical strength in the crosslinked product. More preferably, the glass transition temperature is 0°C or lower, further preferably -20°C or lower, or even -40°C or lower. In this embodiment, since the crosslinkable polymer composition contains Component C, the crosslinked polymer material has excellent mechanical strength, such as abrasion resistance. Therefore, it is not necessary to use a component B with a high glass transition temperature in order to increase the mechanical strength of the crosslinked polymer material. Therefore, although there is no particular lower limit for the glass transition temperature of Component B, it is preferable to set it to -90°C or higher, or even -70°C or higher, from the perspective of ensuring high mechanical strength in the crosslinked polymer material. The glass transition temperature of Component B can be evaluated, for example, according to JIS K 7121. When it is desired to particularly enhance the mechanical strength, including the abrasion resistance, of the crosslinked polymer material, it is also preferable to use, as Component B, a material having a relatively high glass transition temperature, such as above 0° C., or even above 10° C., even if the glass transition temperature is within the range of 10° C. or less. However, even in this case, it is advisable to keep the glass transition temperature of Component B at 20° C. or less, from the viewpoint of ensuring the flexibility of the crosslinked polymer material.

[0082] Component B preferably has a flow initiation temperature in the range of 50° C. to 190° C. This facilitates crosslinking by metal ions liberated from component A to give a crosslinked product having a flow initiation temperature at a moderately high temperature, such as 190° C. to 300° C. or less. It is more preferable that component B has a flow initiation temperature of 80° C. or more and 160° C. or less.

[0083] From the viewpoint of increasing the flexibility of the crosslinked polymer material, the hardness of component B is preferably 60 or less, more preferably 50 or less, or even 40 or less, in Shore D hardness. On the other hand, from the viewpoint of ensuring the mechanical strength of the crosslinked polymer material, the hardness of component B is preferably 10 or more, in Shore D hardness. The Shore D hardness of component B may be measured in accordance with JIS K 6253. Note that, when it is desired to particularly increase the mechanical strength, including the abrasion resistance, of the crosslinked polymer material, it is also preferable to use as component B a component having a Shore D hardness of 60 or less, but relatively high, such as more than 40, or even more than 60. However, even in this case, from the viewpoint of ensuring the flexibility of the crosslinked polymer material, it is preferable to keep the Shore D hardness of component B to 70 or less.

[0084] (4) Component C Component C is composed of a secondary or tertiary amine represented by formula (1) shown below. Here, R １ is a hydrogen atom or a hydrocarbon group having 30 or less carbon atoms, R ２ is a hydrocarbon group having 30 or less carbon atoms, R ３ is a hydrocarbon group having 13 to 30 carbon atoms. １ is a hydrogen atom, the C component is a secondary amine, and R １ When R is a hydrocarbon group, the C component is a tertiary amine. Hereinafter, when referring to the structure of a hydrocarbon group, R １ Unless otherwise specified, the term "a" refers to a form in which the group is a hydrocarbon group rather than a hydrogen atom.

[0085] As explained above, by adding an amine-based component C to a crosslinkable polymer composition, the ammonium cation formed from component C bonds to the electron-withdrawing substituent of component B, thereby suppressing the rate of crosslinking reaction in which component B is crosslinked by metal ions released from component A, thereby improving the spatial uniformity and degree of crosslinking of the crosslinked structure. Here, by limiting component C to a secondary or tertiary amine, it is possible to avoid the formation of an irreversible covalent bond with the substituent of component B, which may occur when component C is a primary amine. As a result, component C can effectively contribute to suppressing the crosslinking rate due to the formation of an ionic bond with component B, and because this ionic bond is reversibly resolvable, the substituent of component B can be maintained in a state available to form an ionic bond with the metal ion released from component A and form a crosslinked structure. Examples of covalent bond formation that may occur when component C is a primary amine include the formation of an imine structure when the substituent of component B is a carboxylic acid group or a carboxylic anhydride group. Either a secondary amine or a tertiary amine may be used as component C, but secondary amines are often solid at room temperature and are therefore easier to handle, so it is preferable to use secondary amines.

[0086] In formula (1), at least one hydrocarbon group, i.e., at least R ３ has 13 or more carbon atoms. This makes it difficult for component C to volatilize during heating and kneading of the crosslinkable polymer composition. In addition, the polarity of component C does not become excessively high, so that it has high compatibility with component B. Since component C is difficult to volatilize and exhibits high compatibility with component B, component C is distributed uniformly and stably in component B, so that component C suppresses the progress of the crosslinking reaction between component B and component A, and the effect of increasing the mechanical strength of the crosslinked polymer material is highly obtained. The other two hydrocarbon groups, namely R １ , R ２ Although there is no particular limitation on the lower limit of the number of carbon atoms in R, the number of carbon atoms in R is preferably 13 or more. ３ (and R １ , R ２ ) may have 15 or more carbon atoms. １ , R２ , R ３ When the number of carbon atoms in the hydrocarbon groups of R is 30 or less, the component C is likely to form an ionic bond in the form of an ammonium cation to the electron-withdrawing substituent of the component B when the crosslinkable polymer composition is heated and kneaded. １ , R ２ , R ３ may all be composed of the same hydrocarbon group, or at least two may be composed of different hydrocarbon groups. From the viewpoint of availability of amines, it is preferred that two or three of the hydrocarbon groups be composed of the same hydrocarbon group.

[0087] Preferably, the hydrocarbon groups constituting the amine of component C are each independently an alkyl group or an aromatic ring group. This minimizes steric hindrance near the nitrogen atom of component C, thereby significantly suppressing the reaction rate of the crosslinking reaction between components A and B. From the viewpoint of further enhancing this effect, when the hydrocarbon group is an alkyl group, the alkyl group is preferably linear. Furthermore, as long as the aromatic ring group contains an aromatic ring, there are no particular restrictions on the presence or absence of a hydrocarbon moiety other than the aromatic ring or the number of aromatic rings, but from the same viewpoint, it is preferable that the number of aromatic rings in each hydrocarbon group is two or less. Furthermore, it is preferable that the aromatic ring is directly bonded to the nitrogen atom.

[0088] Furthermore, Component C is preferably a monoamine containing only one amine structure in the molecule, which makes it difficult for crosslinking between polymer chains of Component B via Component C, which can occur when multiple amine structures are present, and the crosslinked structure is primarily mediated by metal ions derived from Component A.

[0089] Specific examples of component C include the following: secondary amines such as N-methylmyristylamine, N-methylcetylamine, N-methylstearylamine, N-methylbehenylamine, N-methylmontanylamine, N,N-distearylamine, diphenylamine, 4-methyldiphenylamine, 3-methyldiphenylamine, ditolylamine, N-phenylnaphthylamine, N-tolylnaphthylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, and bis(4-octylphenyl)amine; Examples of tertiary amines include N,N-dimethylmyristylamine, N,N-dimethylcetylamine, N,N-dimethylstearylamine, N,N-dimethylbehenylamine, N,N-dimethylmontanylamine, N,N-distearylmethylamine, N-methyldiphenylamine, triphenylamine, methyltriphenylamine, and N,N-diphenylnaphthylamine. From the viewpoints of availability and odor reduction at high temperatures, N,N-dimethylstearylamine, N-methylstearylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, and bis(4-octylphenyl)amine are particularly preferred. As component C, a single compound may be used, or two or more compounds may be used in combination.

[0090] In the crosslinkable polymer composition, the content of component C is preferably 0.5 parts by mass or more, based on 100 parts by mass of the total of components A, B, and C. This effectively suppresses the reaction rate of the crosslinking reaction between components A and B. More preferably, the content of component C is 0.8 parts by mass or more, or 1.0 parts by mass or more, based on the 100 parts by mass. Meanwhile, the content of component C is preferably 20 parts by mass or less, based on the 100 parts by mass. This prevents the formation of aggregates due to component C. Furthermore, component B is contained in a relatively sufficient amount, allowing the crosslinked polymer material to fully exhibit the physical properties provided by component B, such as mechanical strength and low-temperature characteristics. More preferably, the content of component C is 10 parts by mass or less, or 5 parts by mass or less, based on the 100 parts by mass.

[0091] (5) Other Components The crosslinkable polymer composition according to this embodiment may contain, in addition to the above-described components A, B, and C, additives such as flame retardants, copper inhibitors, antioxidants, and colorants, as appropriate, to the extent that the functionality of the material is not impaired. Examples of other additives include metal salts of long-chain carboxylic acids having a structure represented by the following formula (5) and a melting point of 190°C or higher. When melted and liquefied in the crosslinkable polymer composition, these compounds enhance the fluidity of the crosslinked product formed from components A and B, thereby improving the thermal deformation properties of the crosslinkable polymer composition. This makes it easier to heat-mold the crosslinkable polymer composition into a desired shape when heat-mold, such as by extrusion molding, the crosslinkable polymer composition. The amount of this compound added is, for example, in the range of 1.0 to 30 parts by mass, where the total of components A and B is 100 parts by mass. Here, R represents a hydrogen atom or a hydroxyl group. m and n each represent an integer of 1 or more, and m+n is 11 or more and 30 or less. M ｙ＋ represents a metal ion with a valence of y, where y is an integer of 1 or more, and x=y. Note that R and M are unrelated to those in FIGS. 1A to 1C.

[0092] The polymer component may contain an organic polymer other than component B, but the content of such an organic polymer is preferably kept lower than the content of component B. More preferably, the crosslinkable polymer composition contains only component B as the polymer component. Furthermore, examples of components that should not be included in the crosslinkable polymer composition include the following compounds in groups (a) to (f): (a) silane coupling agents, (b) epoxy compounds, (c) isocyanates and isothiocyanate compounds, (d) photoradical generators and thermal radical generators, (e) chlorine compounds and bromine compounds, and (f) volatile organic solvents. If a crosslinkable polymer composition contains compounds in groups (a) to (d), unintended chemical reactions, such as crosslinking of component B through a reaction separate from the crosslinking reaction mediated by metal ions liberated from component A, or cleavage of the main chain of component B, may occur upon heating. This may result in insufficient heat resistance and remoldability of the crosslinkable polymer composition. Furthermore, if a crosslinkable polymer composition contains compounds in group (e), coloration or the generation of corrosive gases may occur upon heating. If a compound of group (f) is contained in the crosslinkable polymer composition, there is a possibility that ignition or the generation of bubbles may occur when the composition is molded. Furthermore, when the crosslinkable polymer composition contains an organic small molecule (a non-polymerized organic molecule), it is preferable that the organic small molecule, like component B, does not contain an ether bond or a cyclic structure such as a steroid skeleton, from the viewpoint of sufficiently ensuring the thermoplasticity, flexibility, and chemical resistance of the polymer material after crosslinking.

[0093] The crosslinkable polymer composition can be prepared by mixing components A, B, and C, as well as optional additional components. Mixing can be performed by heat kneading. The resulting crosslinkable polymer composition can then be molded into any desired shape by heat molding, such as extrusion molding. By performing heat kneading and heat molding at a temperature above the decomposition point or phase transition point of component A, the crosslinkable polymer composition can be molded into a desired shape after the crosslinked product has already been formed from components A and B, or while the crosslinked product is being formed. In this case, separate heating for crosslinking after molding is not required. Furthermore, it is advisable to set the temperature during heat kneading and heat molding to a temperature above the flow initiation temperature of the crosslinked product formed from components A and B. This allows for smooth heat kneading and heat molding while the material remains fluid. Even after the crosslinked polymer material has been molded into a desired shape, the crosslinked polymer material regains its fluidity and can be remolded by heating the molded product to a temperature above the flow initiation temperature of the crosslinked product. Remolding can be repeated reversibly. The crosslinkable polymer composition according to this embodiment can form a crosslinked structure without any operations other than heating, and therefore the crosslinking process can be carried out with simpler equipment than when electron beam crosslinking or silane crosslinking is used. The remolding process can also be carried out by applying an appropriate external force while heating, and therefore can be carried out with similarly simple equipment. In a crosslinked polymer material in which crosslinking of component B with metal ions derived from component A is complete, most of component C returns to the amine state and coexists with the crosslinked product. Therefore, even when the crosslinked polymer material is heated for remolding, it is unlikely that ionic bonds will be formed between the electron-withdrawing substituent of component B in the form of ammonium ions.

[0094] [2] Insulated Wire and Wire Harness The crosslinked polymer material formed from the crosslinkable polymer composition according to this embodiment can be used to construct any desired component. However, the crosslinked polymer material according to this embodiment can be suitably used as a constituent material for insulated wires and wire harnesses for automobiles, etc., taking advantage of its excellent abrasion resistance, high heat resistance and moldability, and resistance to loss of flexibility due to crosslinking. Insulated wires and wire harnesses are prone to heat generation when current is passed through metal components, including electric wire conductors. Therefore, polymer materials placed near these metal components are required to have high heat resistance, such as resistance to irreversible deformation upon heat generation. On the other hand, when the crosslinkable polymer composition is molded into a desired shape by heat molding, such as extrusion molding, it is desirable for the crosslinkable polymer composition to have high fluidity and excellent moldability. Furthermore, in some cases, a polymer material once molded into a predetermined shape may need to be remolded due to deformation of the insulated wire or changes in the configuration of the wire harness.

[0095] In insulated wires and wire harnesses, the crosslinked polymer material according to the embodiment of the present disclosure may be applied to any number of locations, including an insulating coating that covers the outer periphery of the wire conductor of an insulated wire, an exterior material that bundles multiple insulated wires in a wire harness, a wire protection material, and a water stop valve for sealing off a connector. Among these, the insulating coating of an insulated wire is preferably made of the crosslinked polymer material according to the embodiment of the present disclosure. The insulating coating is required to have high mechanical strength that makes it resistant to damage even when contacted with external objects such as other wires, and, as described below, its remoldability can be effectively utilized.

[0096] Fig. 2 shows an example of an insulated wire according to an embodiment of the present disclosure in a cross section perpendicular to the axial direction. The insulated wire 1 shown in Fig. 2 includes a conductor 2 and an insulating coating 3 covering the outer periphery of the conductor 2. The configuration of the conductor 2 is not particularly limited, but it is configured as a stranded conductor in which a plurality of wires 21 are twisted together. In the example shown, the insulated wire 1 is configured to have a flat portion, and the cross section of the conductor 2 has a flat shape (a shape elongated in the width direction). The insulating coating 3 is made of the cross-linked polymer material according to the embodiment of the present disclosure described above. The insulating coating 3 also has a flat cross-sectional outer shape that follows the shape of the conductor 2.

[0097] In the insulated wire 1, heat is generated when a current is applied to the conductor 2, and the insulating coating 3 is also heated. However, the insulating coating 3 is made of the cross-linked polymer material according to the embodiment of the present disclosure described above and has high heat resistance. Therefore, even if the insulating coating 3 is heated, it is unlikely to be affected by heat, such as irreversible deformation.

[0098] The insulated wire 1 has a flat portion, which reduces the space required for routing and improves space-saving performance. By utilizing the remoldability of the cross-linked polymer material constituting the insulating coating 3, the insulated wire 1 having a flat portion can be easily formed using a conventional insulated wire (round wire) with a generally circular cross section. For example, a round wire can be manufactured by extruding a heated and kneaded cross-linkable polymer composition according to an embodiment of the present disclosure onto the outer periphery of the electric wire conductor 2. In this case, if the extrusion molding is performed at a temperature equal to or higher than the decomposition point or phase transition point of component A, the insulating coating 3 can be obtained with a cross-linked body of components A and B formed through the extrusion molding. Furthermore, if the extrusion temperature is set to equal to or higher than the flow initiation temperature of the cross-linked body formed from components A and B, the extrusion molding can be smoothly performed. If the insulated wire is to be used without forming a flat portion, the round wire obtained by this extrusion molding can be used as is.

[0099] To form a flattened portion in an insulated wire, the flattened portion can be easily formed by heating the round wire fabricated as described above to a temperature equal to or higher than the flow temperature of the crosslinked body and applying a compressive force in one direction. Because the conductor 2 is configured as a stranded conductor, it can be easily deformed by the application of force. Furthermore, the insulating coating 3, which is in a fluid state when heated, can also be easily deformed to follow the deformation of the conductor 2. The insulating coating 3 is then allowed to cool and return to its original, stable crosslinked body state. Alternatively, in an already formed flattened portion, the insulating coating 3 can be heated to a temperature equal to or higher than the flow temperature of the crosslinked body and then applied a compressive force from both sides in the width direction to return the flattened portion to the shape of the round wire or a similar shape with a low flatness. In this case, the insulating coating 3 also deforms to a low flatness shape following the deformation of the conductor 2.

[0100] As described above, since the insulating coating 3 is composed of a cross-linked polymer composition containing components A and B, an insulating coating 3 having excellent heat resistance and mechanical strength can be easily formed by extrusion molding onto the outer periphery of the conductor 2. Furthermore, since the insulating coating 3 is composed of a cross-linked body having reversible reshapeability, deformation of the insulated electric wire 1 into any shape, such as bidirectional deformation between a flat cross-sectional shape and a substantially circular cross-sectional shape, can be easily achieved by deforming the insulating coating 3 in accordance with the conductor 2. For example, the cross-sectional shape of the insulated electric wire can be changed with a high degree of freedom, such as by forming flat portions on a round electric wire only in areas where space saving is required in the wiring path. This makes it possible to produce a variety of insulated electric wires having flat portions in different locations using a common electric wire as a raw material. The insulated electric wire may be used alone, or may be used in the form of a wire harness by connecting components such as connecting terminals or bundling with other insulated electric wires.

[0101] Examples are shown below. The present invention is not limited to these examples. Unless otherwise specified, sample preparation and evaluation were carried out at room temperature in the atmosphere.

[0102] <Preparation of Samples> To prepare Samples A1 to A17 and Samples B1 to B15, the A, B, and C components were kneaded according to the formulations (units: parts by mass) shown in Tables 1 and 2. Kneading was performed for 5 minutes at 240°C and 50 rpm using a kneading / extrusion tester ("Labo Plastomill" manufactured by Toyo Seiki Seisaku-sho, Ltd.). The kneaded samples were then press-molded at 240°C for 5 minutes to prepare 2 mm-thick sample sheets. For each evaluation, the sample sheets were left for at least 24 hours after the hot pressing. For at least Samples A1 to A17, crosslinking of Component B by metal ions derived from Component A occurred due to heating to 240°C during kneading and press molding. The progress of crosslinking was confirmed by infrared absorption spectroscopy. Specifically, the C═O stretching vibration (1790 cm ) of the acid anhydride present in the infrared absorption spectrum of Component B before crosslinking was detected. －１ around 1720 cm －１ It was confirmed that the absorption of the α-glucan (near α-glucan) disappeared or decreased with crosslinking.

[0103] The materials used are as follows. (1) Component A The decomposition points or phase transition points obtained from DSC measurements are shown below in parentheses along with the material type. Ca-AA: calcium (II) acetylacetonate (110°C) Zn-AA: zinc (II) acetylacetonate (105°C) Al-AA: aluminum (III) acetylacetonate (112°C) Zr-AA: zirconium (IV) acetylacetonate (180°C) ZnO: zinc (II) oxide (none (>300°C)) stCa: calcium stearate (93°C)

[0104] (2) Component B Below, the material type is shown together with the flow initiation temperature (measured by the same method as in the evaluation method section below), hardness (Shore D hardness measured in accordance with JIS K6253), and glass transition temperature (measured in accordance with JIS K7121).・MAH-SEBS: maleic acid modified hydrogenated styrene thermoplastic elastomer, manufactured by Asahi Kasei Corporation "M1911", flow starting temperature 142°C, D hardness 36, glass transition temperature -51°C ・MAH-EO: maleic acid modified ethylene-α-olefin copolymer, manufactured by Mitsui Chemicals, Inc. "MH5020", flow starting temperature 132°C, D hardness 15, glass transition temperature -49°C ・MAH-EMA: maleic acid modified ethylene-methyl acrylate copolymer, manufactured by SK Functional Polymers, Inc. "OREVAC18603", flow starting temperature 83°C, D hardness 29, glass transition temperature -52°C ・MAH-EVA: maleic acid modified ethylene-vinyl acetate copolymer, manufactured by SK Functional Polymers, Inc. "OREVAC18211", flow starting temperature 42°C, D hardness 10, glass transition temperature -42°C MAH-LLDPE: Maleic acid modified low density polyethylene, SK Functional Polymers "OREVAC18302N", flow starting temperature 95°C, D hardness 18, glass transition temperature -42°C MAH-PP: Maleic acid modified polypropylene, Mitsui Chemicals "Admer QB550", flow starting temperature 142°C, D hardness 58, glass transition temperature 4°C AA-PP: Acrylic acid modified polypropylene, Chemtura "Polybond 1001", flow starting temperature 139°C, D hardness 45, glass transition temperature 8°C EMAA: Ethylene-methacrylic acid copolymer, Mitsui-Dow Polychemicals "N035C", flow starting temperature 65°C, D hardness 41, glass transition temperature 29°C SEBS: Hydrogenated styrene-based thermoplastic elastomer, "H1041" manufactured by Asahi Kasei Corporation, flow starting temperature 137°C, D hardness 36, glass transition temperature -53°C

[0105] (3) Component C The materials used are as follows. DMBA was manufactured by Kao Chemical Corporation, and the others were manufactured by Tokyo Chemical Industry Co., Ltd. DMSA: N,N-dimethylstearylamine DMBA: N,N-dimethylbehenylamine TPA: triphenylamine MDPA: N-methyldiphenylamine MSA: N-methylstearylamine BDA: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine SA: stearylamine DMDA: N,N-dimethyldecylamine

[0106] <Evaluation Method> (1) Flow Initiation Temperature A test piece measuring 10 mm x 10 mm x 2 mm was prepared using the sample sheet. This test piece was placed on a temperature-variable hot plate, and a 2 mmφ cylindrical indenter with a dial gauge attached to the top was pressed against the center of the test piece with a force of 1 N. Thereafter, the temperature of the hot plate was increased at a rate of 5°C / min, and the distance the indenter penetrated into the sample sheet was recorded.

[0107] The temperature at which the indenter penetrated the sample sheet to a depth of 2.0 mm was taken as the flow initiation temperature. Samples with a flow initiation temperature 5°C or higher than that of component B not containing components A and C can be considered to have undergone crosslinking by metal ions, resulting in improved heat resistance.

[0108] (2) Elastic Modulus The sample sheet was cut into strips measuring 50 mm in length, 5 mm in width, and 2 mm in thickness, and subjected to a tensile test at room temperature in the atmosphere with a grip width of 10 mm and a speed of 10 mm / min. The elastic modulus (tensile modulus) was calculated from the strain between a tensile load of 1 N and 2 N.

[0109] (3) Abrasion Resistance Abrasion resistance test was performed on each sample. The sample sheet was cut into a size of 50 mm long x 30 mm wide x 2 mm thick and fixed on the table of a scratch strength tester (manufactured by Shinto Scientific Co., Ltd.). Then, a sapphire scratching needle (R 0.5 mm) with a load of 1 N applied perpendicular to the sample sheet surface was reciprocated 1,000 times at a speed of 55 times / min over a length of 10 mm on the surface of the sample sheet. The depth of the center of the groove formed on the sample sheet surface due to abrasion was then measured using a laser microscope. The smaller the groove depth, the higher the abrasion resistance of the sample. If the groove depth is 250 μm or less, the abrasion resistance can be considered sufficiently high.

[0110] (4) Gel Fraction The sample sheet was cut into small pieces, and approximately 0.1 g was weighed out as the initial mass and placed in a sealed bottle. 20 mL of xylene was added and heated at 120°C for 24 hours. After that, the sample was cooled to room temperature, and the gel fraction was filtered out, dried at 100°C, and weighed as the residual gel fraction mass. The ratio of the residual gel fraction mass to the initial mass was defined as the gel fraction (%). A higher gel fraction indicates a higher crosslink density, and a gel fraction of 80% or more can be considered to have a sufficiently high crosslink density.

[0111] (4) Sheet Appearance The surface of the sample sheet was visually observed and evaluated for appearance. A sample sheet with a uniform surface appearance was evaluated as having a good appearance (A). On the other hand, a sample sheet with a non-uniform surface appearance due to the separation of aggregates or incompatible materials was evaluated as having a poor appearance (B).

[0112] <Evaluation Results> In Tables 1 and 2 below, the content of each component (unit: parts by mass) for Samples A1 to A17 and B1 to B15 is shown in the upper row, and the results of each evaluation are shown in the lower row.

[0113]

[0114]

[0115] According to Table 1, all of Samples A1 to A17 contain, as raw materials, Component A, which liberates metal ions upon heating; Component B, which is composed of an organic polymer containing electron-withdrawing substituents in its side chains capable of forming ionic bonds with metal ions; and Component C, a secondary or tertiary amine having the structure of Formula (1) above. For Samples A1 to A17, the sample sheets obtained through crosslinking during kneading and press molding each had a flow initiation temperature that was at least 5°C higher than the flow initiation temperature of Component B, demonstrating high heat resistance through crosslinking. The flow initiation temperatures of all sample sheets, all of which were at least 190°C, also demonstrate the high heat resistance of the crosslinked bodies. Furthermore, while the molding temperature of typical thermoplastic resins is around 300°C, the sample sheets of Samples A1 to A15 have flow initiation temperatures of 300°C or lower, demonstrating high remoldability.

[0116] Furthermore, for samples A1 to A17, the groove depth in the abrasion test after crosslinking was 250 μm or less, demonstrating high abrasion resistance. Furthermore, for all samples A1 to A17, the gel fraction was 80% or more, resulting in a high crosslink density. It is believed that the contribution of component C suppresses the reaction rate of the crosslinking reaction between components A and B, thereby increasing the crosslink density and resulting in high abrasion resistance for the crosslinked polymer material. Furthermore, each sample had good appearance (A), and a homogeneous material was obtained without the formation of aggregates or separation of incompatible materials. This also indicates that the crosslinking reaction between components A and B did not proceed too quickly, resulting in the formation of heterogeneous structures such as aggregates.

[0117] Although samples A1 to A4 contain different metals in the A component, all of them exhibit high flow initiation temperatures, low moduli, high abrasion resistance, and gel fractions. Although samples A1, A5, and A10 contain different B components, all of them exhibit high flow initiation temperatures, abrasion resistance, and gel fractions. Furthermore, among these, samples A1, A5, and A8, as well as samples A2, A4, and A11, A17, which use the same B component as sample A1, exhibit a modulus of elasticity of 80 MPa or less after crosslinking, combining high flexibility with high abrasion resistance. Meanwhile, samples A9 and A10 use a hard B component with a polypropylene backbone, resulting in a high modulus of elasticity after crosslinking. However, they also exhibit particularly high abrasion resistance, with groove depths of 25 μm or less in abrasion tests.

[0118] Although samples A1 and A11 to A15 contain different types of component C, all of them exhibit a high flow initiation temperature, a low modulus of elasticity, high abrasion resistance, and a gel fraction. Furthermore, samples A1, A16, and A17 differ in the amount of component C. However, sample A1, which contains a moderate amount of component C, exhibits the highest flow initiation temperature, high abrasion resistance, and low gel fraction. It is believed that sample A1 contains a sufficient amount of component C, which significantly suppresses the rate of the crosslinking reaction between components A and B, while also suppressing the formation of aggregates due to the large amount of component C, and providing sufficiently high mechanical strength.

[0119] Among samples B1 to B15 listed in Table 2, samples B1, B2 to B7, and B8 differ from samples A1, A5 to A10, and A4 (hereinafter referred to as corresponding group A samples) in that they do not contain component C. In samples B1 to B8, crosslinking of component B occurs due to metal ions liberated from component A. Similar to the corresponding group A samples, crosslinking increases the flow initiation temperature, resulting in high heat resistance. However, the groove depths in the abrasion resistance test are significantly greater than those of the corresponding group A samples, particularly for samples B1 to B5 and B8, exceeding 250 μm. In other words, the abrasion resistance of all samples B1 to B8 is significantly lower than that of the corresponding group A samples. The gel fractions are also low, less than 80%. It is believed that the absence of component C causes the crosslinking reaction between components A and B to proceed locally at a high rate, preventing a uniform increase in the degree of crosslinking throughout the material, which manifests as a low gel fraction and prevents a sufficient improvement in the mechanical strength of the crosslinked polymer material.

[0120] On the other hand, there is no significant difference in the modulus of elasticity between Samples B1 to B8 and the corresponding Group A samples. This indicates that the improvement in abrasion resistance due to the addition of Component C is not simply due to an increase in modulus of elasticity, but is due to the improvement in the uniformity and degree of crosslinking, which is manifested as an increase in gel fraction, as described above. The fact that the addition of Component C improves abrasion resistance without substantially increasing the modulus of elasticity means that both the reduction in flexibility associated with crosslinking and the improvement in mechanical strength are both achieved at high levels.

[0121] Sample B9 does not contain component A, and therefore crosslinking of component B by metal ions cannot proceed. Therefore, the flow initiation temperature is not elevated compared to that of component B, and is below 190°C. Furthermore, the abrasion resistance is poor, with the groove depth measured in the test exceeding 500 μm. The gel fraction is also less than 5%. In other words, the lack of crosslinking results in no improvement in heat resistance or abrasion resistance.

[0122] In samples B10 and B11, zinc oxide and calcium stearate, respectively, are used as component A rather than a metal complex. These compounds do not liberate metal ions even when heated, and therefore cannot crosslink component B. Correspondingly, like sample B9, samples B10 and B11 also show no significant increase in flow temperature from that of component B, and are well below 190°C. Similar to sample B9, the abrasion resistance and gel fraction are also very low. Thus, like sample B9, samples B10 and B11 do not undergo crosslinking, and therefore do not achieve the improved heat resistance and abrasion resistance that would be achieved by crosslinking.

[0123] In sample B13, component B does not have a substituent capable of forming an ionic bond with a metal ion, and therefore, metal ions derived from component A cannot form a crosslinked structure in component B. Correspondingly, like samples B9 to B11, the flow initiation temperature is not elevated from that of component B and is well below 190°C. Furthermore, the abrasion resistance and gel fraction are also very low. Thus, like samples B9 to B11, sample B13 does not undergo crosslinking, and therefore does not achieve the improved heat resistance and abrasion resistance that would be achieved by crosslinking.

[0124] These samples B9 to B11 and B13 contain component C, but unlike component A, which liberates metal ions, component C does not cross-link component B. In other words, it was confirmed that the effect of improving abrasion resistance by adding component C, confirmed by comparing samples B1 to B8 with the corresponding group A samples, is not due to the physical properties of component C itself, but is only exhibited when component C coexists in a situation where metal ions liberated from component A cross-link component B.

[0125] Sample B12 uses EMAA as component B, and has electron-withdrawing carboxylic acid groups in the polymer main chain, but no electron-withdrawing substituents in the side chains. Due to steric hindrance from adjacent methacryloyl groups, the carboxylic acid groups in the main chain cannot effectively form crosslinked structures via ionic bonds with metal ions. Correspondingly, the flow initiation temperature is significantly lower than 190°C. Furthermore, the groove depth in the abrasion resistance test exceeded 250 μm, and the gel fraction was less than 80%, indicating that crosslinking did not effectively improve heat resistance and abrasion resistance. Furthermore, this is thought to be due to the formation of crosslinked structures in the main chain of component B.

[0126] Sample B14 uses stearylamine (SA), a primary amine, as component C. Even in this sample B14, the flow initiation temperature remains below 190°C, the groove depth in the abrasion resistance test exceeds 500 μm, and the gel fraction is well below 80%. Thus, neither high heat resistance nor the improved abrasion resistance due to the high degree of crosslinking is achieved. In fact, the heat resistance, degree of crosslinking, and abrasion resistance are all lower than those of sample B1, which does not contain an amine as component C. This is interpreted as being due to the primary amine added as component C reacting with the substituent of component B to form an imine structure, which prevents the substituent of component B from forming an ionic bond with the metal ion liberated from component A, resulting in insufficient formation of a crosslinked structure.

[0127] Sample B15 uses N,N-dimethyldecylamine (DMDA) as component C, a tertiary amine in which all hydrocarbon groups are short chains with less than 13 carbon atoms. The appearance of the sample sheet for sample B15 is poor (B). This is thought to be due to the low compatibility between components C and B, resulting in the formation of particulate matter when component C separates from component B. Furthermore, the separation of the particulate matter is thought to inhibit the rate of the crosslinking reaction between components A and B, preventing component C from being effectively utilized to increase the spatial uniformity of the crosslinked structure. This likely results in low abrasion resistance and a low gel fraction.

[0128] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention.

[0129] 1 insulated wire 2 wire conductor 21 wire 3 insulating coating

Claims

1. Component A, which liberates metal ions when heated; Component B is composed of an organic polymer having a side chain, the side chain containing an electron-withdrawing substituent capable of forming an ionic bond with a metal ion liberated from component A; A crosslinkable polymer composition comprising: a component C consisting of a secondary or tertiary amine represented by the following formula (1): 【Chemical 1】 Here, R １ is a hydrogen atom or a hydrocarbon group having 30 or less carbon atoms, R ２ is a hydrocarbon group having 30 or less carbon atoms, R ３ is a hydrocarbon group having 13 to 30 carbon atoms.

2. The crosslinkable polymer composition according to claim 1, wherein the flow initiation temperature of the crosslinked body obtained by crosslinking the B component with the metal ions liberated from the A component is 190°C or higher and 300°C or lower.

3. In the formula (1), R １ is a hydrocarbon group, and R ２ , R ３ The crosslinkable polymer composition according to claim 1 , wherein each of the hydrocarbon groups is independently a linear alkyl group or an aromatic ring group.

4. The crosslinkable polymer composition according to claim 1, wherein the component B has a flow starting temperature in the range of 50°C or higher and 190°C or lower.

5. The crosslinkable polymer composition according to claim 1 , wherein the component A has a decomposition point or a phase transition point of 50° C. or higher and 300° C. or lower.

6. The crosslinkable polymer composition according to claim 1 , wherein the component A has a decomposition point or a phase transition point at a temperature equal to or higher than the flow-initiation temperature of the component B.

7. 2. The crosslinkable polymer composition according to claim 1, wherein the component A is a metal complex containing a ligand having a structure of the following formula (2): 【Chemistry 2】 Here, R ４ and R ５ each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R ６ represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. ４ , R ５ , R ６ The present invention also includes a case where at least two of the groups are connected to each other by a ring structure.

8. 2. The crosslinkable polymer composition according to claim 1, wherein the metal ions liberated from said component A are ions of at least one of alkaline earth metals, aluminum, zinc, titanium, and zirconium.

9. 2. The crosslinkable polymer composition according to claim 1, wherein the substituent of the component B is at least one of a carboxylic acid group, an acid anhydride group, a phosphoric acid group, and an acrylic acid group.

10. 2. The crosslinkable polymer composition according to claim 1, wherein the substituent of the component B is bonded to the main chain via an alkyl group or alkylene group having one or more carbon atoms.

11. The crosslinkable polymer composition according to claim 1 , wherein the component B has a glass transition temperature of 10° C. or less.

12. The crosslinkable polymer composition according to claim 1 , wherein the component B does not contain an electron-withdrawing group in the main chain.

13. The crosslinkable polymer composition according to claim 1 , wherein the main chain of the component B is an olefin-based polymer or a styrene-based polymer.

14. The crosslinkable polymer composition according to claim 1 , wherein the component A is contained in an amount of 0.1 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the total of the components A, B, and C.

15. The crosslinkable polymer composition according to claim 1 , wherein the component C is contained in an amount of 0.5 parts by mass or more and 20 parts by mass or less, based on 100 parts by mass of the total of the components A, B, and C.

16. A material obtained by crosslinking the crosslinkable polymer composition according to any one of claims 1 to 15, a crosslinked product obtained by crosslinking the component B with metal ions liberated from the component A; and the component C.

17. 17. The crosslinked polymeric material of claim 16, having a tensile modulus of less than 20 MPa.

18. A wire conductor; An insulated wire comprising: an insulating coating made of the crosslinked polymer material according to claim 16 and covering the outer periphery of the wire conductor.

19. The electric wire conductor is formed by twisting together a plurality of wires, The insulated wire according to claim 18 , wherein the insulated wire has a flattened portion in which a cross section of the wire conductor perpendicular to the axial direction has a flattened shape.

20. A wire harness comprising the insulated wire according to claim 18.

Images