Silane-crosslinkable resin composition, silane-crosslinked resin molded article, method for producing same, and wiring material

Abstract

Provided are: a silane-crosslinkable resin composition; a silane-crosslinked resin molded article thereof; and a wiring material having the molded article. The silane-crosslinkable resin composition contains 100 parts by mass of a base resin comprising a polyolefin resin, 1-60 parts by mass of a silane coupling agent grafted and bonded to the base resin, a compound having two or more imide structures, and 0.01-5 parts by mass of a silanol condensation catalyst. And a method for producing a silane-crosslinkable resin composition and a silane-crosslinked resin molded article, the method comprising a step in which a base resin, a silane coupling agent, a compound having two or more imide structures, an inorganic filler, an organic peroxide, and a silanol condensation catalyst are melt-mixed at a specific ratio.

Description

Technical Field

[0001] The present invention relates to a silane crosslinkable resin composition, a silane crosslinking resin molded body, methods for producing the same, and a wiring material. Background Art

[0002] Wiring materials such as insulated wires, cables, cords, optical fiber cores, and optical fiber cords (optical fiber cables) used in the electrical / electronic equipment and industrial fields include coatings (insulators, sheaths, etc.) formed from various resin molded bodies or rubber molded bodies. These molded bodies (coatings) are required to have various properties depending on the application and form of use of the wiring material. For example, heat resistance is required from the perspectives of appearance, safety, and reliability.

[0003] A representative technique for improving the heat resistance of wiring materials is to form a coating layer using a crosslinked molded article obtained by crosslinking a resin or rubber. Electron beam crosslinking and chemical crosslinking methods are commonly used for crosslinking such resins or rubbers. Among chemical crosslinking methods, silane crosslinking is commonly used because it allows for simple and efficient crosslinking of silane-crosslinkable resin compositions without requiring specialized equipment.

[0004] As an insulated wire having a coating layer formed by such a silane crosslinking method, for example, Patent Documents 1 and 2 describe an insulated wire having a wire coating material formed by water-crosslinking a wire coating material composition containing a silane-grafted polyolefin, an unmodified polyolefin, a polyolefin modified with a specific functional group, a brominated flame retardant having a phthalimide structure, a crosslinking catalyst, zinc sulfide, and the like.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-057080

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2016-046084 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, in the past, it was believed that the properties of a cross-linked resin molded article (coating layer) produced by a silane cross-linking method not only affect the types and contents of the various components constituting the cross-linked resin molded article, but also affect the grafting reaction of the silane coupling agent, the occurrence and reaction rate of direct cross-linking reactions between resins or rubbers, and various studies have been conducted. Based on this viewpoint, the present inventors have conducted studies on the properties of cross-linked resin molded articles, but have encountered the following problem: even with various improvements or modifications based on this viewpoint, it is still impossible to achieve a balance between the appearance characteristics and heat resistance of the cross-linked resin molded article. However, Patent Documents 1 and 2 do not address this issue.

[0011] The present invention aims to provide a silane crosslinked resin molded body having both excellent appearance characteristics with suppressed appearance defects and the generation of protruding aggregates (concave-convex spots) and sufficient heat resistance due to increased crosslinking density, and a method for producing the same.

[0012] Another object of the present invention is to provide a silane crosslinkable resin composition capable of forming a silane crosslinkable resin molded body having the above-mentioned excellent properties, and a method for producing the same.

[0013] Another object of the present invention is to provide a wiring material having a silane crosslinked resin molded body having the above-mentioned excellent properties as a covering layer.

[0014] Means for solving problems

[0015] The present inventors have continued to investigate the issue of the inability to achieve both aesthetic properties and heat resistance using the silane crosslinking method. They have discovered that the speed (degree of speed) of the reaction (crosslinking rate) in the final crosslinking reaction (silanol condensation reaction) affects the properties of the crosslinked resin molded article, particularly its aesthetic properties and heat resistance. Based on this insight, the present inventors have continued their research and discovered that, during the final crosslinking reaction of a silane crosslinkable resin composition containing a silanol condensation catalyst at a specific ratio relative to a base resin containing a polyolefin resin grafted with a silane coupling agent, by allowing a compound having two or more imide structures to coexist with the silanol condensation catalyst at a specific ratio, the final crosslinking reaction can proceed at a moderate rate, while constructing a sufficient (dense) crosslinked structure resulting from the silanol condensation reaction, while also suppressing the occurrence of poor appearance and uneven spots. As a result, they have discovered that silane crosslinked resin molded articles that achieve both excellent aesthetic properties and sufficient heat resistance can be produced with good productivity. Based on this insight, the present inventors have conducted further research and completed the present invention.

[0016] That is, the subject of the present invention is achieved by the following means.

[0017] <1> A silane crosslinkable resin composition comprises: 100 parts by mass of a base resin comprising a polyolefin resin; a silane coupling agent graft-bonded to the base resin; 1 to 60 parts by mass of a compound having two or more imide structures; and 0.01 to 5 parts by mass of a silanol condensation catalyst.

[0018] <2> according to <1> The silane crosslinkable resin composition, wherein the base resin does not contain a modified polyolefin resin modified with any of carboxylic acid groups, methacryloyl groups and epoxy groups.

[0019] <3> according to <1> or <2> In the silane crosslinkable resin composition, the compound having two or more imide structures does not contain a brominated flame retardant having a phthalimide structure.

[0020] <4> according to <1> ~ <3> The silane crosslinkable resin composition according to any one of the preceding claims contains 1 to 200 parts by mass of an inorganic filler based on 100 parts of the base resin.

[0021] <5> A silane cross-linked resin molded body, which is the above <1> ~ <4> A silane crosslinking resin molded article of the silane crosslinking resin composition according to any one of the preceding claims.

[0022] <6> A wiring material having the above <5> The silane crosslinking resin molded body serves as a covering layer.

[0023] <7> A method for producing a silane crosslinkable resin composition, comprising the step (1) of melt-mixing 2 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of undergoing a grafting reaction with the base resin, 1 to 60 parts by mass of a compound having two or more imide structures, 1 to 200 parts by mass of an inorganic filler, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.01 to 5 parts by mass of a silanol condensation catalyst with respect to 100 parts by mass of a base resin comprising a polyolefin resin, to obtain a silane crosslinkable resin composition, wherein:

[0024] When the above step (1) is performed, when all the base resin is melt-mixed in the following step (a), the above step (1) comprises the following steps (a) and (c). On the other hand, when a part of the base resin is melt-mixed in the following step (a), the above step (1) comprises the following steps (a), (b), and (c).

[0025] Step (a): melt-mixing all or part of the base resin, the inorganic filler, the silane coupling agent, and the organic peroxide at a temperature above the decomposition temperature of the organic peroxide to prepare a silane masterbatch;

[0026] Step (b): melt-mixing the remaining portion of the base resin and the silanol condensation catalyst to prepare a catalyst masterbatch;

[0027] Step (c): a step of melt-mixing the silane masterbatch and the silanol condensation catalyst or the catalyst masterbatch,

[0028] The compound having two or more imide structures is mixed in at least one of the steps (a) and (b).

[0029] <8> according to <7> The method for producing the silane crosslinkable resin composition comprises mixing the entire amount of the compound having two or more imide structures in the step (b).

[0030] <9> A method for producing a silane crosslinked resin molded body, comprising the following steps (1), (2), and (3), wherein:

[0031] Step (1): melt-mixing 2 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of grafting with the base resin, 1 to 60 parts by mass of a compound having two or more imide structures, 1 to 200 parts by mass of an inorganic filler, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.01 to 5 parts by mass of a silanol condensation catalyst with respect to 100 parts by mass of a base resin comprising a polyolefin resin to obtain a mixture;

[0032] Step (2): forming the mixture obtained in the above step (1) to obtain a molded body;

[0033] Step (3): a step of contacting the molded body obtained in the above step (2) with water to obtain a silane crosslinked resin molded body,

[0034] When the above step (1) is performed, when all the base resin is melt-mixed in the following step (a), the above step (1) comprises the following steps (a) and (c). On the other hand, when a part of the base resin is melt-mixed in the following step (a), the above step (1) comprises the following steps (a), (b), and (c).

[0035] Step (a): melt-mixing all or part of the base resin, the inorganic filler, the silane coupling agent, and the organic peroxide at a temperature above the decomposition temperature of the organic peroxide to prepare a silane masterbatch;

[0036] Step (b): melt-mixing the remaining portion of the base resin and the silanol condensation catalyst to prepare a catalyst masterbatch;

[0037] Step (c): a step of melt-mixing the silane masterbatch and the silanol condensation catalyst or the catalyst masterbatch,

[0038] The compound having two or more imide structures is mixed in at least one of the steps (a) and (b).

[0039] <10> according to <9> The method for producing a silane crosslinked resin molded body is characterized in that the entire amount of the compound having two or more imide structures is mixed in the step (b).

[0040] <11> A silane crosslinking resin composition, which is <7> or <8> The manufacturing method is described.

[0041] <12> A silane cross-linked resin molded body, which is obtained by <9> or <10> The manufacturing method is described.

[0042] <13> A wiring material having the above <12> The silane crosslinking resin molded body serves as a covering layer.

[0043] Effects of the Invention

[0044] The present invention can provide a silane crosslinked resin molded body and a method for producing the same, wherein the silane crosslinked resin molded body has both excellent appearance characteristics with suppressed appearance defects and small uneven spots, and sufficient heat resistance due to increased crosslinking density (higher crosslinking density).

[0045] Furthermore, the present invention can provide a silane crosslinkable resin composition capable of forming a silane crosslinkable resin molded body having the above-mentioned excellent properties, and a method for producing the same.

[0046] Furthermore, the present invention can provide a wiring material having a silane crosslinked resin molded body having the above-mentioned excellent properties as a covering layer.

[0047] The above and other features and advantages of the present invention will become more apparent from the following description. DETAILED DESCRIPTION

[0048] In the present invention, about the content, physical properties, etc. of the component, when a numerical range is shown for description, when the upper limit and lower limit of the numerical range are described separately, any upper limit and lower limit can be appropriately combined as a specific numerical range. On the other hand, in the present invention, the numerical range represented by "to" refers to a range containing the numerical values ​​recorded before and after "to" as the lower limit and upper limit. It should be noted that, in the present invention, when multiple numerical ranges are set for description, the upper limit and lower limit forming the numerical range are not limited to the specific combination recorded before and after "to" as a specific numerical range, and can be a numerical range formed by appropriately combining the upper limit and lower limit of each numerical range.

[0049] In the present invention, “(meth)acrylic acid” means either or both of acrylic acid and methacrylic acid, and “(meth)acrylate” means either or both of acrylate and methacrylate.

[0050] [Silane crosslinkable resin composition]

[0051] The silane crosslinkable resin composition of the present invention contains, relative to 100 parts by mass of a base resin comprising a polyolefin resin, a silane coupling agent graft-bonded to the base resin, 1 to 60 parts by mass of a compound having two or more imide structures, and 0.01 to 5 parts by mass of a silanol condensation catalyst.

[0052] As described in detail below, the silane crosslinkable resin composition of the present invention comprises a silane crosslinkable resin formed by graft-bonding (grafting reaction) a silane coupling agent to a base resin, and contains, in a mixed state with the base resin, a compound having two or more imide structures and a silanol condensation catalyst. Furthermore, the silane crosslinkable resin composition of a preferred embodiment described below contains, in addition to the compound having two or more imide structures and the silanol condensation catalyst, a silane crosslinkable resin formed by graft-bonding (grafting reaction) a silane coupling agent bonded to or dissociated from an inorganic filler and a base resin, and an inorganic filler.

[0053] Since the silane crosslinking resin composition of the present invention coexists with a specific amount of a compound having two or more imide structures relative to a specific amount of silanol condensation catalyst, it is believed that special crosslinking equipment such as a chemical crosslinking tube and an electron beam crosslinking machine is not required, and the silanol condensation reaction can occur and be carried out at a moderate reaction speed under mild conditions. As a result, the generation of poor appearance and concave-convex small spots caused by the high-speed silanol condensation reaction can be suppressed, and excellent appearance characteristics can be achieved. In the present invention, poor appearance refers to the surface (appearance) of the silane crosslinking resin molded body (coating layer) obtained by the silane crosslinking resin composition, which is caused by foaming, as well as the concave-convex, roughness and other defects known as so-called melt fracture. In addition, concave-convex small spots refer to gel-like protrusions (gel concave-convex small spots) formed by the final crosslinking (silanol condensation reaction) on the surface of the silane crosslinking resin molded body (coating layer), or condensed concave-convex small spots formed by incompatibility of raw materials. Furthermore, it is possible to suppress the delay in the formation of a crosslinked structure (delay in crosslinking construction) caused by the slowing down of the silanol condensation reaction, thereby suppressing a decrease in crosslinking density (a decrease in heat resistance) and a deterioration in productivity.

[0054] In the present invention, regarding the silanol condensation reaction, a moderate (appropriate) reaction rate (crosslinking rate) cannot be determined solely by the content of the silanol condensation catalyst, the conditions of contact with water, etc. Whether the reaction rate of the silanol condensation reaction is moderate can be determined and evaluated by maintaining the catalytic activity of the silanol condensation catalyst, for example, by passing the appearance characteristics test and the heat deformation test described in the Examples below.

[0055] As described above, the silane crosslinkable resin composition of the present invention can adjust the reaction rate of the silanol condensation reaction to an appropriate reaction rate, and can realize a silane crosslinked resin molded article that achieves a balanced balance between the opposing appearance characteristics and heat resistance by adjusting the speed of the silanol condensation reaction. Therefore, the silane crosslinkable resin composition of the present invention is suitable for use in the silane crosslinked resin molded article and wiring material of the present invention.

[0056] [Silane crosslinked resin molded article]

[0057] The silane crosslinked resin molded article of the present invention is a crosslinked molded article of the silane crosslinkable resin composition of the present invention. Specifically, it is a crosslinked resin molded article obtained by molding the silane crosslinkable resin composition of the present invention into a predetermined shape and size and then subjecting it to silane crosslinking (silanol condensation reaction) (a molded article composed of a silanol condensate of the silane crosslinkable resin composition).

[0058] As described in detail below, the silane crosslinked resin molded article of the present invention is formed by a silanol condensation reaction at a moderate reaction rate using a compound having two or more imide structures and a silanol condensation catalyst. This article has a crosslinked structure (a crosslinked structure obtained by a silane coupling agent or its silanol condensate) in which the base resin is moderately silane-crosslinked. Therefore, the silane crosslinked resin molded article of the present invention exhibits excellent appearance characteristics and sufficient heat resistance in a balanced manner. Furthermore, it is believed that the silane crosslinked resin molded article of the preferred embodiment described below has an inorganic filler incorporated into a portion of the crosslinked structure as described below. Therefore, as described below, the silane crosslinked resin molded article of the preferred embodiment has a balanced construction of a crosslinked structure between the base resins (not via an inorganic filler) and a crosslinked structure in which an inorganic filler is incorporated, thereby exhibiting excellent appearance characteristics and sufficient heat resistance at a high level of balance.

[0059] The silane crosslinked resin molded article of the present invention is molded into an appropriate shape and size depending on the intended use, for example, the use of the wiring material of the present invention described later.

[0060] Hereinafter, each component used in the present invention will be described.

[0061] Each component can be used alone or in combination of two or more.

[0062] It should be noted that in the present invention and this specification, when simply referred to as resin, it refers to the resin in which the silane coupling agent has not undergone a grafting reaction. On the other hand, the resin in which the silane coupling agent has undergone a grafting reaction is sometimes referred to as a silane crosslinking resin, a silane grafted resin, etc.

[0063] In addition, when referring to a (co)polymer, it is used in the sense of including its resin or rubber.

[0064] <Base resin>

[0065] The silane crosslinkable composition of the present invention comprises a polyolefin resin as its base resin, and preferably consists of a polyolefin resin. As described above, the base resin comprises a polyolefin resin (silane crosslinkable resin, silane grafted resin) to which a silane coupling agent has been grafted.

[0066] The silane grafted resin contained in the base resin is formed from a silane coupling agent (described below) and a polyolefin resin, and is a resin formed by a graft reaction between the silane coupling agent and the polyolefin resin. The grafting reaction amount of the silane coupling agent in the silane grafted resin is not particularly limited. Generally, the grafting reaction amount obtained by reacting the silane coupling agent and the polyolefin resin in the blending amount described below will suffice.

[0067] The silane grafted resin may be a suitably synthesized substance or a commercially available product. The silane grafted resin is obtained by reacting a polyolefin resin with a silane coupling agent at a temperature above the decomposition temperature of an organic peroxide. Specific reaction conditions are not particularly limited; however, preferably, the melt mixing conditions of step (1) or step (a) described below are employed, provided that the organic peroxide content is within the range described below. Commercially available silane grafted resins include Linklon (trade name, manufactured by Mitsubishi Chemical Corporation).

[0068] (Polyolefin resin)

[0069] The polyolefin resin (before the grafting reaction) forming the silane grafted resin is not particularly limited as long as it is a resin composed of a polymer obtained by polymerizing or copolymerizing a compound having an ethylenically unsaturated bond (olefin compound), and known polyolefin resins used in conventional resin compositions can be used. It should be noted that in the present invention, in addition to resins composed of polymers obtained by polymerizing or copolymerizing the above-mentioned olefin compounds, the polyolefin resin also includes elastomers and rubbers composed of such polymers.

[0070] The polyolefin resin has a grafting reaction site (e.g., an unsaturated bond site in a carbon chain, a carbon atom having a hydrogen atom) that can undergo a grafting reaction with the grafting reaction site of the silane coupling agent. Examples of such polyolefin resins include polyethylene (PE), polypropylene (PP), ethylene-α-olefin copolymers, copolymers having an acid copolymer component or an acid ester copolymer component, and styrene-based elastomers.

[0071] -Polyethylene resin-

[0072] The polyethylene resin (PE) is not particularly limited as long as it is a polymer resin containing ethylene as a main component, and examples thereof include high-density polyethylene (HDPE), low-density polyethylene (LDPE), ultra-high molecular weight polyethylene (UHMW-PE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (VLDPE). Among them, linear low-density polyethylene and low-density polyethylene resins are preferred.

[0073] -Polypropylene resin-

[0074] The polypropylene resin (PP) is not particularly limited as long as it is a polymer resin containing propylene as a main component. For example, in addition to propylene homopolymers, there can be mentioned resins of random polypropylene and block polypropylene.

[0075] -Ethylene-α-olefin copolymer resin-

[0076] Preferred examples of ethylene-α-olefin copolymer resins include copolymers of ethylene and α-olefins having 3 to 12 carbon atoms (excluding copolymers included in the above-mentioned polyethylene resins and polypropylene resins). Examples thereof include ethylene-propylene copolymer resins (excluding those included in polypropylene resins), ethylene-butene copolymer resins, and ethylene-α-olefin copolymer resins synthesized in the presence of a single-site catalyst.

[0077] -Resin having a copolymer of an acid copolymer component or an acid ester copolymer component-

[0078] The acid copolymer component or acid ester copolymer component introduced into the resin of the copolymer having the acid copolymer component or acid ester copolymer component is not particularly limited, and examples thereof include carboxylic acid compounds such as (meth)acrylic acid, and acid ester compounds such as vinyl acetate and (meth)acrylic acid ester. The (meth)acrylic acid ester is not particularly limited, and examples thereof include alkyl (meth)acrylates. The alkyl group of the alkyl (meth)acrylate is preferably an alkyl group having 1 to 12 carbon atoms.

[0079] The resin of the copolymer having an acid copolymer component or an acid ester copolymer component is not particularly limited, and examples thereof include ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer, and ethylene-alkyl (meth)acrylate copolymer. Specific examples of the ethylene-alkyl (meth)acrylate copolymer include ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer (EBA).

[0080] -Styrene elastomer-

[0081] Styrene-based elastomer refers to the elastomer that is made up of the polymer having the constituent from aromatic vinyl compound in molecule.As such styrene-based elastomer, block copolymer and random copolymer or their hydride etc. of conjugated diene compound and aromatic vinyl compound can be enumerated.Specifically, styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated SIS, styrene-butadiene-styrene block copolymer (SBS), hydrogenated SBS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), hydrogenated acrylonitrile-butadiene rubber (HNBR) etc. can be enumerated.

[0082] -Modified polyolefin resin-

[0083] The base resin may contain a resin obtained by modifying a polyolefin resin.

[0084] Examples of modified polyolefin resins include modified polyolefin resins modified with any of carboxylic acid groups, methacryloyl groups, and epoxy groups, and modified polyolefin resins modified with any of carboxylic acid groups, acid anhydride groups, amino groups, acryloyl groups, methacryloyl groups, and epoxy groups. Such modified polyolefin resins are not particularly limited, and examples thereof include resins comprising polymers obtained by graft-polymerizing a compound having at least one of the above groups onto a polyolefin resin, resins comprising polymers obtained by copolymerizing a compound having at least one of the above groups with an olefin compound, and more specifically, maleic acid-modified polyethylene resins, maleic acid-modified polypropylene resins, resins comprising ethylene-glycidyl methacrylate (E-GMA) copolymers, and resins comprising ethylene-methyl methacrylate (EMMA) copolymers.

[0085] As modified polyolefin resins, compounds having at least one of the above-mentioned groups (corresponding to the "functional group-introduced compound" in each patent document), for example, the contents described in Patent Document 1 or Patent Document 2 can be appropriately referred to, and their contents are directly incorporated as part of the description of this specification.

[0086] -Oil-

[0087] The polyolefin resin may contain various oils used as plasticizers or softeners as desired. Examples of such oils include plasticizers used in polyolefin resins or mineral oil softeners for rubber. As the oil, aromatic oils, paraffin oils, and naphthenic oils are preferably used, with paraffin oil being more preferred.

[0088] (Composition of base resin)

[0089] The base resin may contain any of the above resins alone or a combination of multiple resins. In the present invention, the base resin preferably comprises a polyethylene resin. However, from the perspective of improving manufacturability and enhancing mechanical properties, the base resin may also contain a polyethylene resin or a polyolefin resin other than a polyethylene resin. The base resin is more preferably composed of a polyethylene resin.

[0090] However, the base resin preferably does not contain the modified polyolefin resin described above. If the base resin does not contain the modified polyolefin resin described above, the appearance characteristics can be further improved without compromising sufficient heat resistance, allowing for a silane crosslinked resin molded article that achieves both excellent appearance characteristics and sufficient heat resistance. In the present invention, "the base resin does not contain a modified polyolefin resin" means that the base resin does not intentionally contain or mix a modified polyolefin resin as a base resin, but does not exclude the unavoidable inclusion or mixing of a modified polyolefin resin. For example, the content of the modified polyolefin resin in the base resin can be 4.0% by mass or less, preferably less than 0.5% by mass, relative to 100% by mass of the base resin.

[0091] When the base resin contains multiple resins, as long as the above-mentioned resins or oils are contained in a total content of 100% by mass, it can be appropriately set according to the physical properties, uses, etc. of the silane crosslinked resin molded body. For example, the content of polyethylene resin in 100% by mass of the base resin is preferably 20% to 100% by mass, more preferably 30% to 90% by mass. It should be noted that setting the lower limit of the content of polyethylene resin to 70% by mass is also one of the preferred embodiments. In addition, the content of polypropylene resin, ethylene-α-olefin copolymer resin, or copolymer resin having an acid copolymer component or an acid ester copolymer component in 100% by mass of the base resin is preferably 0% to 80% by mass, more preferably 10% to 70% by mass. On the other hand, the content of styrene elastomer in 100% by mass of the base resin is preferably 0% to 50% by mass, more preferably 5% to 20% by mass. The content of oil in 100% by mass of the base resin is preferably 0% to 50% by mass, more preferably 5% to 20% by mass. It should be noted that when the base resin contains a modified polyolefin resin, the content of the modified polyolefin resin in 100% by mass of the base resin is not particularly limited and can be 5% by mass to 70% by mass, 5% by mass to 40% by mass, or 10% by mass to 30% by mass.

[0092] <Compounds Having Two or More Imide Structures>

[0093] Compounds having two or more imide structures (hereinafter sometimes referred to as polyimide compounds) are compounds having two or more amino groups (-NR-) or two carbonyl groups bonded to amine in their molecular structure: -CO-NR2-CO-. Here, R2 represents a hydrogen atom, a substituent, or a bonding moiety. Substituents that can serve as R2 are not particularly limited, and examples thereof include alkyl groups, alkenyl groups, and aryl groups.

[0094] In the polyimide compound, the imide structure may be a linear imide structure, but is preferably a cyclic imide structure (introducing an imide structure to form a ring). In the cyclic imide structure, the number of imide structures introduced into one ring (cyclic chain) may be one or more. In the present invention, the compound having two or more imide structures generally includes: a compound in which two imide structures exist independently via atoms or linking groups (for example, a compound represented by formula (1) or formula (2) described later); a compound in which a carbonyl group, an amino group, or an ammonia of an imide structure is shared with another imide structure (for example, a compound having an isocyanurate ring structure described later); and a compound in which the above two forms are mixed. As a compound in which a carbonyl group, an amino group, or an ammonia of an imide structure is shared with another imide structure, a compound comprising a chain represented by -CO-NR2-CO-NR2-CO-(R2 as described above) can be cited, and the compound is interpreted as having two imide structures. The chain may be introduced into the ring in the polyimide compound. Examples of the ring structure composed of three imide structures include an isocyanurate ring structure.

[0095] Examples of the cyclic imide structure include a maleimide ring structure, a succinimide ring structure, a glutarimide ring structure, or a ring structure formed by condensing a benzene ring with these ring structures, such as a ring structure having one imide structure in the ring, and a ring structure having two or more imide structures in the ring, such as an isocyanurate ring structure. Preferably, the ring structure has one imide structure in the ring, and more preferably, a maleimide ring structure or a ring structure formed by condensing a benzene ring with a maleimide ring structure (e.g., a phthalimide structure). The bonding portion in the cyclic imide structure may be any atom, preferably an atom forming a cyclic structure, and more preferably a nitrogen atom forming a cyclic structure (R2 described above).

[0096] The imide structure possessed by the polyimide compound can be more than 2 in 1 molecule. When the polyimide compound is a high molecular compound, preferably a polymer, the imide structure present in 1 molecule can be appropriately set according to the molecular weight of the high molecular compound, for example, it can be 2 to 100. On the other hand, when the polyimide compound is a low molecular compound, usually a non-polymer compound (also referred to as a monomer compound), the imide structure present in 1 molecule is, for example, preferably 2 to 4, more preferably 2. The imide structures having two or more may be different, but are preferably the same.

[0097] The polyimide compound may be a high molecular compound (polymer), but is preferably a low molecular compound (non-polymer).

[0098] As such a polyimide compound, various compounds can be cited as described later. From the aspect of environmental adaptability, compounds other than brominated flame retardants having a phthalimide structure are preferred (i.e., the polyimide compound does not include a brominated flame retardant having a phthalimide structure), compounds other than flame retardants are more preferred (i.e., the polyimide compound does not include a flame retardant), and compounds other than polyimide compounds having halogen atoms are further preferred (i.e., the polyimide compound does not include a polyimide compound having a halogen atom).

[0099] In the present invention, the polyimide compound does not contain a brominated flame retardant, etc., which means that the polyimide compound does not actively contain or mix a brominated flame retardant, etc., and does not exclude the possibility that the polyimide compound inevitably contains a brominated flame retardant, etc. For example, the polyimide compound may contain 0.5% by mass or less of a brominated flame retardant, etc. relative to 100% by mass of the polyimide compound.

[0100] The polyimide compound is not particularly limited and includes, for example, monomer compounds that form bismaleimide resins. Preferred are imide compounds having two cyclic imide structures represented by the following formula (1) or formula (2), and more preferred are compounds represented by the following formula (1).

[0101] [Chemistry 1]

[0102]

[0103] In formula (1) and formula (2), R represents a linking group.

[0104] The linking group that can be used as R is not particularly limited, and examples thereof include an alkylene group, an alkenylene group, an arylene group, an oxygen atom (—O—), a sulfur atom (—S—), an imino group, or a combination thereof.

[0105] The alkylene group that can be used as R is not particularly limited and may be any of a linear, branched, or cyclic chain, with linear or branched chains being preferred. The number of carbon atoms in the alkylene group is not particularly limited, but is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 3. The bonding positions of the alkylene group are not particularly limited and may be the same carbon atom or different carbon atoms. When bonding positions are different carbon atoms, the carbon atoms at both ends of the longest carbon chain forming the alkylene group are preferred.

[0106] There are no particular limitations on the alkenylene group that can be used as R. It may be linear, branched, or cyclic, preferably linear or branched. The number of carbon atoms in the alkenylene group is not particularly limited, but is preferably 2 to 6, more preferably 2 to 3.

[0107] The arylene group that can be used as R is not particularly limited and may be a monocyclic or polycyclic arylene group, preferably a monocyclic arylene group. The number of carbon atoms in the arylene group is not particularly limited, but is preferably 6 to 24, more preferably 6 to 10, and even more preferably 6. In the case of a monocyclic arylene group (phenylene), the bonding position is not particularly limited and may be any of 1,2-phenylene, 1,3-phenylene, and 1,4-phenylene, preferably 1,3-phenylene or 1,4-phenylene, and more preferably 1,4-phenylene.

[0108] The imino group that can be used as R is not particularly limited, and examples thereof include -NR N - the group shown. N It represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and is preferably a hydrogen atom.

[0109] The above-mentioned combination of groups that can be used as R is not particularly limited, and appropriate groups or atoms can be combined. The number of groups and atoms constituting the combination is not particularly limited, and can be, for example, 2 to 10, preferably 3 to 7. Examples of the above-mentioned combination of groups include groups consisting of a combination of an alkylene group and an arylene group, a group consisting of a combination of an arylene group and an oxygen atom, a group consisting of a combination of an alkylene group, an arylene group and an oxygen atom, and a group consisting of a combination of an alkylene group and a sulfur atom. Examples of groups consisting of a combination of an alkylene group and an arylene group include arylene-alkylene-arylene. Examples of groups consisting of a combination of an arylene group and an oxygen atom include arylene-oxygen atom-arylene. Examples of groups consisting of a combination of an alkylene group, an arylene group and an oxygen atom include arylene-oxygen atom-arylene-alkylene-arylene-oxygen atom-arylene. Examples of the group composed of a combination of an alkylene group and a sulfur atom include an alkylene group-sulfur atom-sulfur atom-alkylene group.

[0110] The arylene group included in the combined group is preferably a phenylene group, and preferably a 1,4-phenylene group.

[0111] In the present invention, the number of atoms constituting the linking group R is not particularly limited and can be 3 to 100, more preferably 20 to 70. The number of linked atoms of the linking group is preferably 50 or less, more preferably 5 to 30, and even more preferably 7 to 20. The above-mentioned number of linked atoms refers to the minimum number of atoms that link the nitrogen atoms contained in the two maleimide rings to each other. For example, when the linking group R is -(1,4-phenylene)-CH2-(1,4-phenylene)-, the number of atoms constituting the linking group is 23, but the number of linked atoms is 9.

[0112] The linking group that can be used as R is preferably an alkylene group, an arylene group, a group consisting of a combination of an alkylene group and an arylene group, or a group consisting of a combination of an alkylene group, an arylene group, and an oxygen atom.

[0113] The compound represented by the above formula (1) or formula (2) may be unsubstituted or may have a substituent. The substituents that these compounds may have are not particularly limited, and examples thereof include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups, alkoxy groups, amino groups, and halogen atoms. Among them, preferably no halogen atoms are contained, and for example, alkyl groups are preferred.

[0114] The number of carbon atoms of the alkyl group is not particularly limited, but is preferably 1 to 20, more preferably 1 to 6. The number of carbon atoms of the alkenyl group and the alkynyl group is not particularly limited, but is preferably 2 to 20. The number of carbon atoms of the aryl group is the same as the number of carbon atoms of the arylene group that can be used as R. Examples of the heterocyclic group include cyclic groups having at least one oxygen atom, sulfur atom, or nitrogen atom, preferably a 5-membered or 6-membered heterocyclic group having 2 to 20 carbon atoms. The heterocyclic group includes aromatic heterocyclic groups and aliphatic heterocyclic groups. The number of carbon atoms of the alkyl group constituting the alkoxy group is not particularly limited, but is the same as the number of carbon atoms of the above-mentioned alkyl group. As the amino group, in addition to the unsubstituted amino group (-NH2), it also includes an amino group in which one or two hydrogen atoms are substituted by an alkyl group, an aryl group, or a heterocyclic group. As the halogen atom, there is no particular limitation, and examples include a fluorine atom, a chlorine atom, and a bromine atom, preferably a bromine atom.

[0115] The number of substituents possessed by the compound represented by formula (1) or formula (2) is not particularly limited and can be one or more and less than the number of hydrogen atoms possessed by these compounds. In the compound represented by formula (2), all four hydrogen atoms of each benzene ring can be substituted. It should be noted that the substitution position of the substituent possessed by the compound represented by formula (1) or formula (2) is not particularly limited.

[0116] Examples of the compound represented by formula (1) include phenylmethanemaleimide, o-phenylenebismaleimide, m-phenylenebismaleimide, p-phenylenebismaleimide, 4-methyl-1,3-phenylenebismaleimide, 1,6-bismaleimide (2,2,4-trimethyl) hexane, 4,4'-diphenylmethanebismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4,4'-diphenyl ether bismaleimide, alkylene bismaleimide having 1 to 6 carbon atoms, 1,3-bis(3-maleimidephenoxy)benzene, and 1,3-bis(4-maleimidephenoxy)benzene.

[0117] Examples of the compound represented by formula (2) include brominated flame retardants such as ethylenebis(tetrabromophthalimide) and ethylenebis(tribromophthalimide).

[0118] Examples of the polyimide compound having an isocyanurate ring structure include triallyl isocyanurate and brominated flame retardants such as tris(2,3-dibromopropyl)isocyanurate.

[0119] <Silanol Condensation Catalyst>

[0120] The silanol condensation catalyst has the function of promoting the condensation reaction of the reactive sites capable of silanol condensation of the silane coupling agent grafted to the base resin in the presence of water (moisture). Due to the action of the silanol condensation catalyst, the base resin is crosslinked by the silane coupling agent.

[0121] Such silanol condensation catalysts are not particularly limited, and examples thereof include organotin compounds, metal soaps, platinum compounds, etc. Examples of organotin compounds include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctoate, and dibutyltin diacetate.

[0122] <Silane coupling agent>

[0123] The silane crosslinkable resin composition of the present invention contains a silane coupling agent graft-bonded to a polyolefin resin (base resin). The polyolefin resin to which the silane coupling agent is graft-bonded is preferably prepared by grafting the silane coupling agent with the polyolefin resin using a method described below.

[0124] The silane coupling agent (before the grafting reaction) that forms the silane grafted resin is not particularly limited as long as it has a grafting reaction site (group or atom) capable of grafting onto a grafting reaction site of the polyolefin resin in the presence of free radicals generated by decomposition of an organic peroxide, and a reaction site capable of silanol condensation. The silane coupling agent used in the present invention preferably has a hydrolyzable silyl group, particularly an alkoxysilyl group, as a reaction site capable of silanol condensation, from the perspective of exhibiting equivalent reactivity in the final crosslinking reaction (particularly silanol condensation reaction).

[0125] Examples of such silane coupling agents include those conventionally used in silane crosslinking methods. Preferred silane coupling agents include those having an ethylenically unsaturated group and a hydrolyzable silyl group (e.g., an alkoxysilyl group). Specifically, examples include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinyldimethoxyethoxysilane, vinyldimethoxybutoxysilane, vinyldiethoxybutoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and vinyltriacetoxysilane, and (meth)acryloxysilanes such as methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, and methacryloxypropylmethyldimethoxysilane. Among them, in the present invention, vinylalkoxysilane is preferred, and vinyltrimethoxysilane or vinyltriethoxysilane is particularly preferred, from the viewpoint that the grafting reaction with the polyolefin resin and the silanol condensation reaction proceed rapidly.

[0126] The silane coupling agent may be used alone or in combination of two or more, and may be used directly or after being diluted with a solvent or the like.

[0127] <Inorganic filler>

[0128] The silane crosslinkable composition of the present invention preferably further contains an inorganic filler. In particular, when a silane coupling agent is subjected to a graft reaction with a polyolefin resin during preparation of the silane crosslinkable resin composition, the presence of an inorganic filler is preferred from the perspectives of suppressing volatilization of the silane coupling agent, suppressing condensation reactions between the silane coupling agents, and further improving appearance characteristics and heat resistance.

[0129] The inorganic filler is not particularly limited as long as it is a commonly used inorganic filler. However, it is preferably an inorganic filler having a site on its surface that can chemically bond with the reactive site of the silane coupling agent capable of silanol condensation via a hydrogen bond, a covalent bond, or an intermolecular bond. The site capable of chemically bonding with the silane coupling agent is not particularly limited, and examples thereof include OH groups (hydroxyl groups, water molecules containing water or crystal water, carboxyl groups, etc.), amino groups, and SH groups.

[0130] If such an inorganic filler is coexisted during the silane grafting reaction, a silane grafted resin formed by a grafting reaction of a silane coupling agent that is weakly bonded to the inorganic filler and a silane grafted resin formed by a grafting reaction of a silane coupling agent that is strongly bonded to the inorganic filler can be formed. By subjecting these two silane grafted resins to a cross-linking reaction, a silane cross-linked resin molded body that exhibits a high cross-linking density (heat resistance) without compromising excellent appearance characteristics can be formed. Here, as examples of weaker bonds with the inorganic filler, interactions based on hydrogen bonds, interactions between ions, partial charges or dipoles, and effects based on adsorption can be cited. In addition, as stronger bonds with the inorganic filler, chemical bonds to chemically bondable sites on the surface of the inorganic filler can be cited.

[0131] As inorganic filler, can enumerate the commonly used inorganic filler in the resin combination, can enumerate for example aluminium hydroxide, magnesium hydroxide, boehmite, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminium nitride, aluminium borate whisker, hydrated aluminium silicate, hydrated magnesium silicate, basic magnesium carbonate, hydrotalcite, talcum etc. have the metal hydrate of the compound of hydroxyl or crystal water.In addition, can enumerate boron nitride, silicon dioxide (crystalline silicon dioxide, amorphous silicon dioxide etc.), carbon black, clay (calcined clay), zinc oxide, tin oxide, titanium oxide, molybdenum oxide, antimony trioxide, organosilicon compound, quartz, zinc borate, white carbon black, zinc borate, hydroxy zinc stannate, zinc stannate etc.Wherein, preferred aluminium hydroxide or magnesium hydroxide.

[0132] In the present invention, when the polyimide compound does not contain a brominated flame retardant having a phthalimide structure, it is preferred that antimony trioxide is not contained as an inorganic filler.

[0133] In the present invention, "not containing antimony trioxide as an inorganic filler" means that antimony trioxide is not actively contained or mixed, but does not exclude the inevitable inclusion of antimony trioxide as an inorganic filler in the silane crosslinkable resin composition and the silane crosslinkable resin molded article. For example, the silane crosslinkable resin composition and the silane crosslinkable resin molded article may contain less than 30 parts by mass of antimony trioxide, preferably less than 10 parts by mass, per 100 parts by mass of the base resin.

[0134] The inorganic filler is preferably a particle, and its average particle size is preferably 0.2 μm to 10 μm, more preferably 0.3 μm to 8 μm, further preferably 0.4 μm to 5 μm, and particularly preferably 0.4 μm to 3 μm. The average particle size is determined by using an optical particle size analyzer such as a laser diffraction / scattering particle size distribution analyzer, using an alcohol- or water-dispersed inorganic filler.

[0135] Inorganic fillers surface-treated with various surface treatment agents may be used.

[0136] The inorganic filler may be used alone or in combination of two or more.

[0137] <Organic Peroxides>

[0138] When synthesizing silane grafted resins, it is preferred to use organic peroxides. Organic peroxides generate free radicals by thermal decomposition, thereby playing a role in initiating and promoting the grafting reaction through the free radical reaction between the silane coupling agent and the base resin. Such organic peroxides are not particularly limited, for example, preferably have the general formula: R 1A -OO-R 2A 、R 3A -OO-C(=O)R 4A 、R 5A C(=O)-OO(C=O)R 6A The compound shown. Here, R 1A ~R 6A Each independently represents an alkyl group, an aryl group or an acyl group. 1A ~R 6A A compound in which all the groups are alkyl groups, or a compound in which any one of the groups is alkyl and the rest are acyl groups.

[0139] The decomposition temperature of the organic peroxide is preferably 80° C. to 195° C., particularly preferably 125° C. to 180° C., as measured by the method described in JP-A-2016-121203.

[0140] Examples of such organic peroxides include those described in paragraph

[0036] of JP-A-2016-121203, which is incorporated herein by reference, and the contents of which are incorporated herein as part of the description of this specification. Among these, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (Perhexa25B), and 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne are preferred.

[0141] <Carrier Resin>

[0142] The above-mentioned silanol condensation catalyst is mixed with a resin or rubber as desired. Such resin or rubber (also referred to as a carrier resin) is not particularly limited, and the components described for the base resin can be used. From the perspective of compatibility with the base resin, the carrier resin is preferably at least one of the components constituting the base resin, and preferably contains the same components as the base resin.

[0143] <Additives>

[0144] The silane crosslinkable composition of the present invention may contain various additives commonly used in resin compositions. Examples of such additives include antioxidants, lubricants, metal deactivators, plasticizers, flame retardants, flame retardant aids, and (co)polymers other than those described for the base resin.

[0145] (Composition of Silane Crosslinkable Resin Composition)

[0146] The content of the compound having two or more imide structures in the silane crosslinkable resin composition is 1 to 60 parts by mass relative to 100 parts by mass of the base resin. If the silane crosslinkable resin composition contains a compound having two or more imide structures within this range, the silanol condensation reaction, which is the final crosslinking reaction, can proceed at a moderate rate together with the silanol condensation catalyst, thereby forming a sufficient crosslinked structure based on the silanol condensation reaction. This also suppresses appearance defects and the formation of small uneven spots, thereby achieving a silane crosslinked resin molded article that achieves both appearance characteristics and heat resistance. To achieve a high level of balance between the appearance characteristics and heat resistance of the silane crosslinked resin molded article, the content of the compound having two or more imide structures in the silane crosslinkable resin composition is preferably 2 to 60 parts by mass, more preferably 5 to 50 parts by mass, and even more preferably 7.5 to 45 parts by mass relative to 100 parts by mass of the base resin.

[0147] In addition, when the polyimide compound reacts or decomposes, it is the content converted into the mass before reaction or decomposition.

[0148] The content of the silane coupling agent in the silane crosslinkable resin composition is not particularly limited. However, from the perspective of suppressing appearance defects, the formation of uneven spots, and volatilization of the silane coupling agent, and enabling the production of a silane crosslinked resin molded article having excellent appearance characteristics and sufficient crosslinking density (heat resistance), the content is preferably 2 to 15 parts by mass, more preferably 2.5 to 10 parts by mass, and even more preferably 3 to 7.5 parts by mass, relative to 100 parts by mass of the base resin. In the silane crosslinkable resin composition, the silane coupling agent is graft-bonded to the polyolefin resin. However, for convenience, the content of the silane coupling agent is calculated as the amount before the grafting reaction with the polyolefin resin (the amount of the silane coupling agent used in combination with the polyolefin resin).

[0149] The content of the silanol condensation catalyst in the silane crosslinkable resin composition is 0.01 to 5 parts by mass relative to 100 parts by mass of the base resin. If the silane crosslinkable resin composition contains a silanol condensation catalyst within this range, the silanol condensation reaction, which is the final crosslinking reaction, can proceed at a moderate rate along with the compound having two or more imide structures, thereby constructing a sufficient crosslinked structure based on the silanol condensation reaction. Furthermore, the occurrence of poor appearance and uneven spots can be suppressed, resulting in a silane crosslinked resin molded article that achieves both appearance characteristics and heat resistance. From the perspective of achieving a high level of balanced balance between the appearance characteristics and heat resistance of the silane crosslinked resin molded article, the content of the silanol condensation catalyst in the silane crosslinkable resin composition is preferably 0.05 to 4 parts by mass, more preferably 0.075 to 3.5 parts by mass, even more preferably 0.1 to 3 parts by mass, and even more preferably 0.1 to 1 part by mass relative to 100 parts by mass of the base resin.

[0150] In the silane crosslinkable resin composition, the mass ratio of the polyimide compound content to the silanol condensation catalyst content [polyimide compound content / silanol condensation catalyst content] is not particularly limited and can be appropriately set. For example, from the perspective of achieving a high level of balance between the appearance characteristics and heat resistance of the silane crosslinkable resin molded article, the mass ratio [polyimide compound content / silanol condensation catalyst content] can be 0.2 to 6,000, preferably 10 to 600.

[0151] In the present invention, from the perspective of achieving a high level of balance between the appearance characteristics and heat resistance of the silane crosslinking resin composition, the contents of the compound having two or more imide structures, the silane coupling agent, and the silanol condensation catalyst can be set by appropriately combining the preferred ranges of the respective components.

[0152] The content of the inorganic filler in the silane crosslinkable resin composition is not particularly limited. For example, from the perspective of further improving the appearance characteristics and heat resistance of the silane crosslinked resin molded article, the content is preferably 0.5 to 400 parts by mass, and more preferably 1 to 200 parts by mass, relative to 100 parts by mass of the base resin. In the present invention, the use of a compound having two or more imide structures can significantly increase the gel fraction, and by reducing the content of the inorganic filler, the extruded appearance can be improved. In this case, the content of the inorganic filler can be, for example, 1 to 300 parts by mass, more preferably 5 to 250 parts by mass, particularly preferably 10 to 200 parts by mass, and most preferably 20 to 100 parts by mass, relative to 100 parts by mass of the base resin.

[0153] In a silane crosslinkable resin composition, when an organic peroxide is used in the grafting reaction between the silane coupling agent and the base resin, the amount of the organic peroxide used is not particularly limited. For example, from the perspective of enabling efficient generation and progression of the grafting reaction between the silane coupling agent and the base resin, the amount of the organic peroxide used is preferably 0.01 to 0.6 parts by mass, more preferably 0.05 to 0.5 parts by mass, and even more preferably 0.1 to 0.2 parts by mass relative to 100 parts by mass of the base resin. However, in a silane crosslinkable resin composition, the organic peroxide generally decomposes during the grafting reaction.

[0154] The total content of additives in the silane crosslinkable resin composition is not particularly limited and can be appropriately set within a range that does not impair the effects of the present invention. For example, the content of the antioxidant is not particularly limited but is preferably 0.2 to 8 parts by mass per 100 parts by mass of the base resin.

[0155] (Composition of Silane Crosslinked Resin Molded Body)

[0156] Silane crosslinking resin molded articles are formed by molding a silane crosslinking resin composition and then contacting it with water to undergo a silanol condensation reaction. Therefore, the contents of the aforementioned components in the molded article are generally the same as those in the silane crosslinking resin composition. However, organic peroxides and silanol condensation catalysts typically decompose. It should be noted that the content of the silane coupling agent refers to the content before the silanol condensation reaction, while the content of the base resin refers to the content before crosslinking.

[0157] In the silane crosslinkable resin composition and the silane crosslinked resin molded article of the present invention, the polyimide compound is generally not considered to directly undergo a crosslinking reaction with the polyolefin resin. However, depending on the type of the polyimide compound, for example, it is considered that it may be hydrolyzed (imide bond cleavage) and react with other components.

[0158] [Method for producing silane crosslinkable resin composition]

[0159] The silane crosslinkable resin composition of the present invention can be prepared by mixing the above-mentioned components.

[0160] In the method using a silane grafted resin, the silane grafted resin, a compound having two or more imide structures, a silanol condensation catalyst, and, if appropriate, an inorganic filler and additives can be melt-mixed to prepare a silane crosslinkable resin composition. The melt-mixing method and conditions can be the same as those described in step (1) or step (a) below.

[0161] On the other hand, in the method of preparing a silane crosslinkable resin composition by grafting a polyolefin resin with a silane coupling agent, the polyolefin resin, the silane coupling agent, an organic peroxide, a compound having two or more imide structures, a silanol condensation catalyst, an inorganic filler added as appropriate, and additives can be mixed to prepare the composition. The mixing method (mixing order) and conditions are not particularly limited, and the composition can preferably be prepared by any method for mixing the inorganic filler in the method for producing the silane crosslinkable resin composition described below in a preferred embodiment.

[0162] The silane crosslinkable resin composition of a preferred embodiment containing an inorganic filler can be prepared by mixing the components as described above, except that the inorganic filler is an essential component. However, it is preferably prepared by the method for producing a silane crosslinkable resin composition of a preferred embodiment described below (hereinafter sometimes referred to as the method for producing the preferred crosslinkable resin composition of the present invention).

[0163] [Method for producing a silane crosslinked resin molded body]

[0164] The silane crosslinked resin molded article of the present invention can be produced by molding the silane crosslinkable resin composition of the present invention and then contacting it with water to cause a crosslinking reaction (silanol condensation reaction). The molding method and molding conditions of the silane crosslinkable resin composition, and the method and contact conditions of the water contact are not particularly limited, and the methods and conditions described in steps (2) and (3) below can be applied.

[0165] A preferred embodiment of a silane crosslinked resin molded article containing an inorganic filler can be produced in the same manner as the silane crosslinked resin molded article of the present invention, except that a preferred embodiment of the silane crosslinked resin composition is used. It is preferably produced by the method for producing a silane crosslinked resin molded article of a preferred embodiment described below (hereinafter sometimes referred to as the preferred molded article production method of the present invention).

[0166] [Preferred method for producing the crosslinkable resin composition of the present invention and preferred method for producing the molded article of the present invention]

[0167] The following describes a preferred method for producing a crosslinkable resin composition and a preferred method for producing a molded article of the present invention (the two methods may be collectively referred to as the preferred method of the present invention). Both methods involve grafting a polyolefin resin with a silane coupling agent during composition preparation.

[0168] Step (1): A step of melt-mixing 2 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of grafting reaction with the base resin, 1 to 60 parts by mass of a compound having two or more imide structures, 1 to 200 parts by mass of an inorganic filler, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.01 to 5 parts by mass of a silanol condensation catalyst with respect to 100 parts by mass of a base resin comprising a polyolefin resin to obtain a mixture (a preferred embodiment of a silane crosslinkable resin composition).

[0169] Step (2): a step of molding the mixture obtained in step (1) to obtain a molded body.

[0170] Step (3): a step of bringing the molded body obtained in step (2) into contact with water to obtain a silane crosslinked resin molded body.

[0171] The above-mentioned step (1) includes the following steps depending on the usage (blending) method of the base resin.

[0172] That is, when performing this step (1), when all the base resins are melt-mixed in the following step (a), the following step (1) includes the following step (a) and step (c). On the other hand, when a part of the base resins are melt-mixed in the following step (a), the following step (1) includes the following step (a), step (b), and step (c).

[0173] In addition, the compound having two or more imide structures can be mixed in at least one of the following steps (a) and (b). From the perspective of further improving the appearance characteristics while maintaining sufficient heat resistance, it is preferred that the entire amount be mixed in the following step (b).

[0174] Step (a): a step of melt-mixing all or part of the base resin, the inorganic filler, the silane coupling agent, and the organic peroxide at a temperature not lower than the decomposition temperature of the organic peroxide to prepare a silane masterbatch.

[0175] Step (b): a step of melt-mixing the remaining portion of the base resin and the silanol condensation catalyst to prepare a catalyst masterbatch.

[0176] Step (c): a step of melt-mixing the silane masterbatch and the silanol condensation catalyst or the catalyst masterbatch.

[0177] In the preferred production method of the present invention, the blending amounts of the various components used as the base resin are the same as the aforementioned contents described above as part of the base resin composition. Furthermore, the blending amounts of the compound having two or more imide structures, the silanol condensation catalyst, and the additives are the same as those in the aforementioned silane crosslinkable resin composition. It should be noted that the blending amount of the silane coupling agent is 2 to 15 parts by mass per 100 parts by mass of the base resin, and the blending amounts are otherwise the same as those in the aforementioned silane crosslinkable resin composition. Furthermore, the blending amount of the inorganic filler is 1 to 200 parts by mass per 100 parts by mass of the base resin, and the blending amounts are otherwise the same as those in the aforementioned silane crosslinkable resin composition.

[0178] In a preferred production method of the present invention, the mixture obtained in step (1) may contain 100 parts by mass of the base resin. For example, in step (a), both the entire amount (100 parts by mass) of the base resin and a portion of the base resin may be mixed.

[0179] When a portion of the base resin is mixed in step (a), the proportion thereof is preferably 60% to 95% by mass, more preferably 70% to 85% by mass, based on 100% by mass of the base resin mixed in steps (a) and (b). The remainder of the base resin (carrier resin) mixed in step (b) is appropriately determined based on the portion of the base resin mixed in step (a).

[0180] In addition, when a part of a base resin is mixed in step (a), the mixed component may be one kind or two or more kinds.

[0181] A portion of the inorganic filler may be used in a step other than step (a), such as step (b). However, from the perspective of being able to construct a balanced crosslinked structure between the base resins (not through the inorganic filler) and a crosslinked structure involving the inorganic filler, it is preferred that the entire amount be used in step (a). When an inorganic filler is used in step (b), the amount used is not particularly limited and can be appropriately determined.

[0182] Various additives may be mixed in either step (a) or step (b).

[0183] <Process (1)>

[0184] In a preferred production method of the present invention, step (1) is performed: a base resin, a silane coupling agent, a compound having two or more imide structures, an inorganic filler, an organic peroxide, and a silanol condensation catalyst are melt-mixed in the aforementioned mixing amounts to prepare a silane crosslinkable resin composition as a preferred embodiment of the mixture.

[0185] Step (1), namely, melt mixing of the base resin, the silane coupling agent, the compound having two or more imide structures, the inorganic filler, the organic peroxide, and the silanol condensation catalyst, is performed in the following order.

[0186] (Step (a))

[0187] In a preferred production method of the present invention, step (a) is performed: all or part of the base resin, inorganic filler, silane coupling agent, organic peroxide, and a compound having two or more imide structures added as appropriate are melt-mixed in the aforementioned mixing amounts at a temperature above the decomposition temperature of the organic peroxide to prepare a silane masterbatch (silane MB).

[0188] In step (a), the mixing temperature for melt mixing (also referred to as melt kneading) of the above components is above the decomposition temperature of the organic peroxide, preferably the decomposition temperature of the organic peroxide + (25 to 110)°C, more preferably 150 to 230°C, and even more preferably 175 to 210°C. Here, the decomposition temperature of the organic peroxide used as a reference for the melt mixing temperature is the temperature under normal pressure (about 0.1 MPa). Mixing conditions such as the mixing time can be appropriately set. For example, the mixing time can be 1 to 25 minutes, preferably 3 to 20 minutes. By melt mixing at a temperature above the decomposition temperature of the organic peroxide, the organic peroxide undergoes thermal decomposition to generate free radicals, thereby carrying out a grafting reaction.

[0189] As mixing method, as long as it is the method normally used in the mixing of rubber, plastics, etc., it is not particularly limited. As mixing device, for example, single screw extruder, twin screw extruder, roller, Banbury mixer or various kneaders etc. are used, preferably closed mixers such as Banbury mixer or various kneaders.

[0190] The mixing method of the base resin is also not particularly limited. For example, the base resin may be prepared in advance and used, or each component may be used separately.

[0191] In the preferred manufacturing method of the present invention, the mixing order of the components in step (a) is not particularly limited, and the components can be mixed in any order. For example, the components can be melt-mixed at one time, or they can be mixed in the following mixing order through the following steps (a-1) and (a-2). It should be noted that when a compound having two or more imide structures is mixed in step (a), the compound having two or more imide structures can be mixed in any of the following steps.

[0192] Step (a-1): a step of mixing an inorganic filler and a silane coupling agent to prepare a mixture

[0193] Step (a-2): A step of melt-mixing the mixture obtained in step (a-1) with all or part of the base resin in the presence of an organic peroxide at a temperature higher than the decomposition temperature of the organic peroxide.

[0194] In step (a-1), by pre-mixing the inorganic filler and the silane coupling agent, a silane coupling agent that is weakly bonded to or adsorbed by the inorganic filler and a silane coupling agent that is strongly bonded to or adsorbed by the inorganic filler can be formed in a balanced manner. This effectively prevents volatilization of the silane coupling agent and condensation reactions between unadsorbed silane coupling agents during melt mixing in step (a-2).

[0195] The mixing method and mixing conditions in step (a-1) are not particularly limited. Examples include dry or wet mixing using a known mixer, kneader, etc., typically at a temperature below the decomposition temperature of the organic peroxide, preferably 10°C to 60°C, more preferably around room temperature (20°C to 25°C), for a period of several minutes to several hours. Dry mixing (dry blending) at a temperature below the decomposition temperature of the organic peroxide is preferred. Other dry mixing conditions can be appropriately determined.

[0196] In step (a-1), the base resin can be mixed as long as the temperature is kept lower than the above-mentioned decomposition temperature.

[0197] The organic peroxide only needs to be present during the melt mixing in step (a-2). The organic peroxide may be mixed in step (a-2), but is preferably mixed in step (a-1).

[0198] Next, the mixture obtained in step (a-1), all or part of the base resin, and the remaining components not mixed in step (a-1) are melt-mixed in the presence of an organic peroxide at a temperature above the decomposition temperature of the organic peroxide to prepare silane MB (step (a-2)). During the melt mixing in this step, the volatilization and self-condensation of the silane coupling agent can be suppressed while preventing excessive cross-linking reaction between the base resins (generating gel irregularities).

[0199] The melt mixing method and conditions in the step (a-2) are not particularly limited, and the melt mixing method and conditions in the above-mentioned step (a) can be applied.

[0200] In step (a-2), at least the following methods are considered as the grafting reaction method of the silane coupling agent and the base resin. Specifically, a method in which the silane coupling agent, which is bonded or adsorbed to the inorganic filler with a relatively weak bond, is separated from the inorganic filler and grafted to the base resin. In this method, the cross-linked structure formed in step (3) described later does not incorporate the inorganic filler and generally becomes a cross-linked structure via a silanol condensate between the silane coupling agents. Alternatively, a method in which the silane coupling agent, which is bonded or adsorbed to the inorganic filler with a relatively strong bond, grafts to the base resin while maintaining the bond or adsorption to the inorganic filler. In this method, the cross-linked structure formed in step (3) described later incorporates the inorganic filler and becomes a cross-linked structure starting from the inorganic filler via the silane coupling agent bonded thereto. By combining the cross-linked structures of the above two methods, a highly developed cross-linked structure can be constructed, including a cross-linked structure in which the inorganic filler is entangled in the silane cross-linked resin molded body.

[0201] In step (a), additives and the like can also be mixed. However, in step (a), it is preferred that a silanol condensation catalyst is not substantially mixed. Thus, the occurrence of the silanol condensation reaction of the silane coupling agent can be suppressed. In the present invention, "substantially not mixed" means that the silanol condensation catalyst that is inevitably present is not excluded, and as long as it is within the range that can suppress the silanol condensation reaction, for example, within the range of 0.01 parts by mass or less relative to 100 parts by mass of the base resin, it can also be present.

[0202] The silane MB prepared in step (a) comprises a reaction mixture of a base resin, a silane coupling agent, a compound having two or more imide structures, and an inorganic filler, and contains a silane grafted resin in which the silane coupling agent is graft-bonded to the base resin to such an extent that the silane coupling agent can be formed in step (b) described below. The silane coupling agent graft-bonded to the base resin includes a silane coupling agent bonded to or adsorbed on the inorganic filler at a reactive site capable of silanol condensation.

[0203] Silane MB is preferably in the form of pellets or powder.

[0204] (Step (b))

[0205] In a preferred production method of the present invention, step (b) is carried out independently of step (a) or after step (a): the remaining portion of the base resin (carrier resin), the silanol condensation catalyst and a compound preferably having two or more imide structures are melt-mixed to prepare a catalyst masterbatch (catalyst MB).

[0206] The mixing ratio of the carrier resin, the silanol condensation catalyst, and the compound having two or more imide structures is not particularly limited, but is preferably set so as to satisfy the above-mentioned mixing amount in step (1).

[0207] The melt mixing method and conditions in step (b) are not particularly limited, and the melt mixing method and conditions described in step (a) above can be applied. For example, the melt mixing temperature may be equal to or higher than the melting temperature of the base resin, preferably 120°C to 200°C, more preferably 140°C to 180°C. Other conditions, such as mixing time, can be appropriately set. For example, the mixing time can be 1 minute to 25 minutes, preferably 3 minutes to 20 minutes.

[0208] Catalyst MB is preferably in the form of pellets or powder.

[0209] (Step (c))

[0210] In a preferred production method of the present invention, the following step (c) is performed: silane MB and a silanol condensation catalyst or catalyst MB are melt-mixed to obtain a mixture. Preferably, silane MB and catalyst MB are melt-mixed.

[0211] The mixing method is not particularly limited and is essentially the same as the melt mixing in step (a), requiring mixing at least at a temperature at which the base resin melts. The mixing conditions in step (c) are not particularly limited, and the mixing conditions described in step (a) above can be applied. For example, the mixing temperature is appropriately selected based on the melting temperature of the base resin or carrier resin, preferably from 80°C to 250°C, more preferably from 100°C to 240°C, and even more preferably from 120°C to 200°C. Other conditions, such as the mixing time, can be appropriately adjusted.

[0212] In the melt mixing of step (c), a melt mixing method and conditions are set to maintain the fluidity (formability) of the mixture. The silane grafted resin in the mixture is an uncrosslinked body in which the silane coupling agent has not undergone silanol condensation. In practice, if melt mixing is performed in step (c), partial crosslinking (partial crosslinking) is unavoidable, but the resulting mixture maintains formability. For example, in order to avoid the occurrence or progress of the silanol condensation reaction, it is preferred that the silane MB and the silanol condensation catalyst are not kept at a high temperature for a long time when mixed.

[0213] In step (c), silane MB and silanol condensation catalyst or catalyst MB are preferably dry-mixed before melt-mixing. The dry-mixing method and conditions are not particularly limited, and examples thereof include the dry-mixing and conditions in step (a-1).

[0214] In this manner, the silane crosslinkable resin composition of a preferred embodiment of the present invention is produced as a mixture.

[0215] The silane crosslinkable resin composition contains a silane grafted resin, a silanol condensation catalyst, an inorganic filler, a compound having two or more imide structures, and the like. In the silane grafted resin, the reactive site of the silane coupling agent capable of undergoing silanol condensation can be bonded to or adsorbed on the inorganic filler, but does not undergo silanol condensation. Therefore, the silane grafted resin includes a silane grafted resin formed by grafting a silane coupling agent bonded to or adsorbed on the inorganic filler and a base resin, and a silane grafted resin formed by grafting a silane coupling agent not bonded to or adsorbed on the inorganic filler and a base resin.

[0216] <Process (2)>

[0217] In the preferred method for producing a molded article of the present invention, the following step (2) is performed: the mixture obtained in the step (1) (the silane crosslinkable resin composition of the preferred embodiment of the present invention) is molded to obtain a molded article.

[0218] The molding method is not particularly limited and can be appropriately selected according to the form of the target product. Examples of the molding method include extrusion molding using an extruder, extrusion molding using an injection molding machine, molding using other molding machines, and spiral molding described below. When manufacturing wiring materials, extrusion molding is preferred from the perspectives of productivity and the ability to co-extrude with a conductor.

[0219] The molding conditions (melt mixing conditions) are not particularly limited as long as they allow uniform mixing and molding and prevent the silane crosslinkable resin composition of the preferred embodiment of the present invention from undergoing a silanol condensation reaction. For example, the melt mixing method and conditions of step (a) can be applied.

[0220] When using an extruder, the temperature of the extruder also depends on various conditions such as the type of base resin and the pulling speed of the conductor, but is preferably 120°C to 180°C in the barrel and approximately 160°C to 200°C in the crosshead (die). The screw speed and molding speed (line speed) of the extruder during extrusion molding are not particularly limited and can be appropriately set based on the characteristics and performance of the extruder, the extrusion volume (coating amount), etc. The line speed can generally be 1 m / min to 20 m / min.

[0221] Step (2) can be performed simultaneously with or continuously with step (c). For example, a series of steps can be employed in which the silane MB and the silanol condensation catalyst or catalyst MB are mixed by dry blending or the like immediately before entering the coating device (extruder), followed by melt mixing in the coating device (step (c)), or the silane MB and the silanol condensation catalyst or catalyst MB are separately introduced into the coating device and melt mixed (step (c)), followed by (co-extrusion) molding onto the outer peripheral surface of a conductor or the like (step (2)).

[0222] In this manner, a molded article (uncrosslinked molded article) of the silane crosslinkable resin composition of a preferred embodiment of the present invention is obtained. This molded article, like the silane crosslinkable resin composition of the preferred embodiment, cannot avoid partial crosslinking of the silane crosslinkable resin, but is in a partially crosslinked state that maintains the moldability that enables molding in step (2). Therefore, the silane crosslinkable resin molded article of the preferred embodiment of the present invention is made into a crosslinked or finally crosslinked molded article by carrying out step (3).

[0223] <Process (3)>

[0224] In a preferred method for producing a molded article of the present invention, step (3) is then performed: the molded article obtained in step (2) is brought into contact with water to produce a silane crosslinked resin molded article of a preferred embodiment of the present invention. Since the molded article obtained in step (2) is an uncrosslinked silane crosslinked resin, this step causes a silanol condensation reaction (dehydration condensation reaction) to occur and proceed (promote) at the reaction sites capable of silanol condensation of the silane coupling agent grafted and bonded to the base resin, ultimately leading to silane crosslinking. In this manner, a silane crosslinked resin molded article crosslinked by silanol condensation of the silane coupling agent can be obtained.

[0225] The contact of the uncrosslinked molded body with water can be carried out by a conventional method. As long as the silanol condensation reaction is in the presence of water, it can be carried out even if it is placed in a temperature environment of about room temperature, for example, 20°C to 25°C, so it is not necessary to actively contact with water. From the viewpoint of promoting the silanol condensation reaction (crosslinking reaction), it is preferred to actively contact the uncrosslinked molded body with water. As a contact method, the method (condition) commonly used in the silane crosslinking method can be cited, and for example, a method of contact under a normal pressure environment can be cited. Specifically, exposure to a saturated water vapor atmosphere, exposure to a high humidity environment, immersion in room temperature water or warm water (for example, 50°C to 90°C), placement in a wet heat tank, exposure to high-temperature water vapor, etc. can be cited. In addition, pressure can also be applied to allow moisture to penetrate into the interior during contact.

[0226] In this manner, a silane crosslinked resin molded article according to a preferred embodiment of the present invention is produced.

[0227] The silane crosslinked resin molded article comprises a silane crosslinked resin formed by condensing a base resin (silane crosslinkable resin) via siloxane bonds. Furthermore, the silane crosslinked resin molded article contains an inorganic filler, which can bond to the silane coupling agent of the crosslinked base resin. Therefore, it is believed that the silane crosslinked resin includes: a crosslinked resin formed by bonding (crosslinking) multiple base resins to or adsorbed onto an inorganic filler via a silane coupling agent, and a crosslinked resin formed by bonding (crosslinking) the inorganic filler and the silane coupling agent; and a crosslinked resin formed by crosslinking (not via an inorganic filler) via a silane coupling agent (siloxane bond) by hydrolysis of the reactive sites capable of silanol condensation in the silane coupling agent grafted to the base resin, which undergo a silanol condensation reaction.

[0228] In a preferred method for producing a molded article of the present invention, a compound having two or more imide structures is present when the final cross-linking reaction in step (3) occurs and proceeds. Therefore, the final cross-linking reaction (silanol condensation reaction) in step (3) can proceed at a moderate reaction rate, and a silane cross-linked resin molded article can be produced that achieves a balanced balance between the opposing appearance characteristics and heat resistance by varying the speed of the silanol condensation reaction.

[0229] The silane-crosslinked resin molded article of the present invention has excellent appearance and high heat resistance, making it suitable for use in a variety of products (including semi-finished products, parts, and components). Specifically, it can be used as a substitute for resin molded articles such as insulating coatings (including sheaths) for wiring materials, molding materials, power plugs, connectors, sleeves, boxes, tape substrates, tubes, heat-resistant sheets, heat-resistant films, gaskets, spacers, cushioning materials, and shockproof materials. In particular, utilizing the excellent properties of the silane-crosslinked resin molded article of the present invention, it is suitable for use as an insulating coating for insulated wires for vehicles such as automobiles and electric trains, and as a sheath for rubber-insulated cables.

[0230] [Wiring materials]

[0231] The wiring material of the present invention comprises a tubular silane crosslinked resin molded article of the present invention or a preferred embodiment of the silane crosslinked resin molded article of the present invention as a coating (insulating layer, sheath, etc.) covering the outer periphery of a conductor. The wiring material (coating layer) of the present invention exhibits excellent appearance characteristics and high heat resistance. Unless otherwise specified, the wiring material of the present invention refers to wiring materials used for internal or external wiring of electrical / electronic equipment, including insulated wires, cables, cords, optical fiber core wires, or optical fiber cords (optical fiber cables).

[0232] The wiring material of the present invention is similar to conventional wiring materials used in various electrical and electronic equipment and industrial fields, except that the covering layer is formed from the silane crosslinked resin molded article of the present invention or a preferred embodiment of the silane crosslinked resin molded article of the present invention. When the covering layer of the wiring material is composed of multiple layers, at least one layer may be formed from the silane crosslinked resin molded article of the present invention or a preferred embodiment of the silane crosslinked resin molded article of the present invention. The covering layer formed from the silane crosslinked resin molded article of the present invention or a preferred embodiment of the silane crosslinked resin molded article of the present invention is provided directly on the outer peripheral surface of the conductor or via another layer. The presence or absence of the other layer and the material thereof are appropriately determined depending on the type of wire, application, required properties, etc.

[0233] Conventional conductors can be used, including single or stranded wires (wires formed by longitudinally adding or twisting tensile fibers) of soft copper, copper alloy, or aluminum. In addition to bare wire, tinned conductors or conductors with an enameled insulating layer can also be used. The thickness of the coating formed from the silane crosslinked resin molded article of the present invention or a preferred embodiment of the silane crosslinked resin molded article of the present invention is not particularly limited, but is generally approximately 0.15 mm to 5 mm.

[0234] The wiring material of the present invention can be produced by molding the silane crosslinkable resin composition of the present invention or the silane crosslinkable resin molded article of the preferred embodiment of the present invention into an annular layer (tubular shape) on the outer peripheral surface of a conductor, and then contacting it with water to cause a crosslinking reaction (silanol condensation reaction). Preferably, in the above-mentioned preferred molded article production method of the present invention, the wiring material can be produced by making the molding step (2) a step of co-extrusion molding the silane crosslinkable resin composition of the preferred embodiment of the present invention onto the outer periphery of the conductor using a coating device (extruder). It should be noted that in the above-mentioned preferred molded article production method of the present invention, by not mixing an inorganic filler, as a step of co-extrusion molding the silane crosslinkable resin composition of the present invention onto the outer periphery of the conductor, a wiring material having a coating layer formed of the silane crosslinkable resin composition of the present invention can be produced.

[0235] Example

[0236] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited thereto.

[0237] The details of each compound used in Examples and Comparative Examples are shown in Tables 1 to 3 and below.

[0238] <Base resin>

[0239] (Silane grafted resin)

[0240] Linklon XCF730M (trade name): silane-grafted polyethylene, silane coupling agent content 5% by mass, manufactured by Mitsubishi Chemical Corporation

[0241] (Polyolefin resin)

[0242] LLDPE: Evolue SP0540 (trade name), linear low-density polyethylene, manufactured by Prime Polymer

[0243] PP: PB222A (trade name), manufactured by SunAllomer, random polypropylene resin

[0244] EVA: Evaflex EV360 (trade name), ethylene-vinyl acetate copolymer resin, manufactured by DOW-MITSUIPOLYCHEMICALS

[0245] Metallocene plastomers: Kernel KS-240T (trade name), polyethylene, manufactured by Japan Polyethylene Co., Ltd.

[0246] SEEPS: SEPTON 4077 (trade name), styrene-ethylene-ethylene-propylene-styrene block copolymer, manufactured by Kuraray Co., Ltd.

[0247] Oil: COSMO NEUTRAL 500 (trade name), paraffin oil, manufactured by COSMO OIL LUBRICANTS

[0248] Maleic modified PP: ADMER QE800 (trade name), manufactured by Mitsui Chemicals

[0249] Epoxy-modified PE: BONDFAST E (trade name), manufactured by Sumitomo Chemical Co., Ltd.

[0250] <Compounds Having Two or More Imide Structures>

[0251] 4,4'-Diphenylmethanebismaleimide: BMI-1000H, manufactured by Yamato Chemical Industry Co., Ltd.

[0252] Bisphenol A diphenyl ether bismaleimide: BMI-4000, manufactured by Yamato Chemical Industry Co., Ltd.

[0253] 3,3'-Dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide: BMI-5100, manufactured by Yamato Chemical Industry Co., Ltd.

[0254] Phenylmethanemaleimide: BMI-2300, manufactured by Yamato Chemical Industry Co., Ltd.

[0255] Triallyl isocyanurate: TAIC (trade name), manufactured by Mitsubishi Chemical Corporation

[0256] Tris(2,3-dibromopropyl)isocyanurate: TAIC-6B (trade name), manufactured by Mitsubishi Chemical Corporation

[0257] Ethylenebis(tetrabromophthalimide): CG-952, manufactured by SUN CHEMICAL

[0258] <Silane coupling agent>

[0259] Silane coupling agent: KBM-1003 (trade name), manufactured by Shin-Etsu Chemical Co., Ltd., vinyltrimethoxysilane

[0260] <Organic Peroxides>

[0261] Organic peroxide: Perhexa 25B (trade name), manufactured by NOF Corporation, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, decomposition temperature 154°C

[0262] <Inorganic filler>

[0263] Magnesium hydroxide: MAGSEEDS FK640 (trade name), manufactured by Kamishima Chemical Industry Co., Ltd.

[0264] <Silanol Condensation Catalyst>

[0265] Dioctyltin dilaurate: ADK STAB OT-1 (trade name), manufactured by ADEKA Corporation

[0266] (Examples 1 to 25 and Comparative Examples 1 to 4)

[0267] Examples 1 to 25 and Comparative Examples 1 to 4 were implemented using the components shown in Tables 1 to 3, respectively.

[0268] In Tables 1 to 3, the numerical values ​​of the compounding amounts (contents) of each example represent parts by mass unless otherwise specified. In addition, a blank column for each component means that the compounding amount of the corresponding component is 0 parts by mass.

[0269] In each of the Examples (except Example 11) and Comparative Examples, a portion (30% by mass) of the base resin was used as a carrier resin for Catalyst MB.

[0270] The silane grafted resin or polyolefin resin, modified polyolefin resin, inorganic filler, organic peroxide, silane coupling agent, and polyimide compound shown in the "Silane MB" column of Tables 1 to 3 were melt-mixed at 170°C to 200°C using a Banbury mixer in the mass ratios shown in the columns, and then pelletized to prepare silane MB pellets (step (a)).

[0271] On the other hand, the carrier resin, silanol condensation catalyst and polyimide compound shown in the "Catalyst MB" column of Tables 1 to 3 are melt-mixed at 170°C to 200°C using a Banbury mixer in the mass ratio shown in the column, and then pelletized to prepare pellets of Catalyst MB (step (b)).

[0272] Next, the prepared silane MB pellets and catalyst MB pellets were dry-mixed at room temperature (25°C) for 2 minutes using a tumble mixer immediately before extrusion molding in the mass ratios shown in the "Silane MB" and "Catalyst MB" columns of Tables 1 to 3 to obtain a dry blend (dry mixing step of step (c)).

[0273] Next, a 25 mm (screw diameter) extruder with L / D (ratio of screw effective length L to diameter D) = 25 was set to three zones on the feeder side of the barrel portion at a die temperature of 200°C or less, and the extrusion temperature conditions were set to C3 = 180°C, C2 = 160°C, and C1 = 140°C. The prepared dry blend was introduced into the extruder and melt-mixed at a screw speed of 10 rpm to 40 rpm (melt mixing step of step (c)). The outer diameter of the conductor becomes Extrusion coating was performed by adjusting the line speed so as to achieve a thickness of 0.35 mm to obtain a coated conductor (step (2)). In this case, the dry blend was melt-mixed in the extruder before extrusion molding to prepare a silane crosslinkable resin composition.

[0274] The obtained covered conductor was left to stand in an environment of room temperature (25° C.) and a relative humidity of 50 RH% for 12 hours to allow the silane crosslinkable resin composition to come into contact with water (step (3)).

[0275] In this manner, an electric wire having a coating layer formed of a silane crosslinked resin molded body was produced.

[0276] The following tests were performed on each of the manufactured electric wires, and comprehensive evaluation was performed based on the test results. The results are shown in Tables 1 to 3.

[0277] <Comprehensive Evaluation>

[0278] In the following Tests 1 and 2, the case where all the results passed was indicated as "0" and the case where at least one result failed was indicated as "×".

[0279] <Test 1: Appearance Characteristics Test>

[0280] The appearance test for electric wires is an alternative test for evaluating the crosslinking rate (silanol condensation reaction rate) of a silane crosslinkable resin composition (silane crosslinked resin molded article). The surface of the coating layer of each manufactured electric wire is visually inspected to evaluate the presence of appearance defects and small uneven spots.

[0281] Specifically, as "appearance defects," the presence of foaming, unevenness, or roughness on the surface of the coating layer was checked. Furthermore, as "concave and convex spots," the presence of gel-like protruding aggregates (gel concave and convex spots) formed by the final cross-linking reaction (silanol condensation reaction) or aggregated concave and convex spots due to raw material incompatibility was checked on the surface of the coating layer.

[0282] Regarding the evaluation, the case where no appearance defects or uneven spots were confirmed on the surface of the coating layer was considered very good and was indicated as "◎". The case where the appearance defects or uneven spots were confirmed in the electric wire immediately after manufacture (up to a manufacturing length of 5 m (excluding 5 m)), but no appearance defects or uneven spots were confirmed in the electric wire with a manufacturing length of 5 m or more and up to 10 m (excluding 10 m) was considered good and was indicated as "○". The case where no appearance defects or uneven spots were confirmed for the first time in the electric wire with a manufacturing length of 10 m or more and up to 50 m (excluding 50 m) was considered acceptable and was indicated as "△". The case where the appearance defects or uneven spots were confirmed also in the electric wire with a manufacturing length of 50 m or more was considered unacceptable and was indicated as "×".

[0283] <Test 2: Heating deformation test>

[0284] This test is a low-speed alternative test for evaluating the heat resistance (crosslinking density) and crosslinking speed of the coating layer. The heat deformation rate of each manufactured electric wire was measured in accordance with UL758.

[0285] Specifically, a load of 2.45 N was applied to each manufactured wire in a direction perpendicular to the longitudinal direction at a measurement temperature of 121°C. The deformation rate of the coating layer at this time was calculated as ([(coating layer thickness before heating - coating layer thickness after heating) / coating layer thickness before heating] × 100) as the heating deformation rate.

[0286] If the heating deformation rate is less than 30%, the silanol condensation reaction proceeds rapidly, and a high crosslinking density can be constructed (achieving high heat resistance). It is expressed as "◎" as very good, "○" as good when it is 30% or more and less than 40%, "△" as qualified when it is 40% or more and less than 50%, and "×" as unqualified when it is 50% or more.

[0287] <Test 3: Hydrogen halide gas generation test>

[0288] Test pieces (2 g) collected from the coating of each manufactured electric wire were quantitatively analyzed for halogen elements in accordance with JCS (Japanese Cable Makers' Association Standard) No. 397 A-98 Item 7. Specifically, the test pieces were burned at 750°C or higher for 30 minutes in a quartz glass combustion tube. The generated gas was then absorbed by the liquid in an absorption bottle. The absorption liquid was then examined and its pH was measured.

[0289] This test was a reference test. In the evaluation, a pH of 4.0 or higher in the absorption liquid was considered good (low generation of hydrogen halide gas) and was indicated as "0", while a pH of less than 4.0 was considered high generation of hydrogen halide gas (unacceptable) and was indicated as "×".

[0290] [Table 1]

[0291]

[0292] [Table 2]

[0293]

[0294] [Table 3]

[0295]

[0296] The following can be seen from the results shown in Tables 1 to 3.

[0297] That is, in Comparative Examples 1 to 4, in which the content of the silanol condensation catalyst or the compound having two or more imide structures in the silane crosslinkable resin composition was outside the range specified in the present invention, no silane crosslinking resin molded article exhibiting excellent appearance characteristics and high heat resistance could be produced.

[0298] In contrast, Examples 1 to 25, in which a compound having two or more imide structures coexists at a specific ratio relative to the silanol condensation catalyst during the final crosslinking reaction of a silane-crosslinkable resin composition containing a silanol condensation catalyst at a specific ratio, all produced silane-crosslinked resin molded articles exhibiting excellent appearance characteristics and high heat resistance with excellent manufacturability. This is believed to be because the silanol condensation reaction, the final crosslinking reaction in the silane crosslinking method, can be caused to proceed at a moderate reaction rate. In other words, the reaction rate of the silanol condensation reaction can be adjusted to a level that achieves both excellent appearance characteristics and high heat resistance.

[0299] In particular, if the modified polyolefin resin mentioned above is not included as a base resin, the generation of small uneven spots can be effectively suppressed and the appearance characteristics can be improved to a high level. On the other hand, if a brominated flame retardant having a phthalimide structure or an isocyanurate ring structure is not included as a compound having two or more imide structures, it is possible to achieve both excellent appearance characteristics and high heat resistance, and the generation of hydrogen halide gas is also suppressed, and environmental adaptability is also excellent.

[0300] The present invention has been described in conjunction with its embodiments, but the applicant believes that unless otherwise specified, the present invention is not limited to any details in the description and should be broadly interpreted without violating the spirit and scope of the invention as shown in the appended claims.

[0301] This application claims priority based on Japanese Patent Application No. 2023-049377, filed in Japan on March 27, 2023, the contents of which are incorporated herein by reference as a part of the description of this specification.

Claims

1. A silane crosslinkable resin composition comprising: 100 parts by mass of a base resin comprising a polyolefin resin; a silane coupling agent graft-bonded to the base resin; 1 to 60 parts by mass of a compound having two or more imide structures; and 0.01 to 5 parts by mass of a silanol condensation catalyst.

2. The silane crosslinkable resin composition according to claim 1, wherein The base resin does not contain a modified polyolefin resin modified with any one of a carboxylic acid group, a methacryloyl group and an epoxy group.

3. The silane crosslinkable resin composition according to claim 1 or 2, wherein The compound having two or more imide structures does not include a brominated flame retardant having a phthalimide structure.

4. The silane crosslinkable resin composition according to any one of claims 1 to 3, wherein The inorganic filler is contained in an amount of 1 to 200 parts by mass based on 100 parts of the base resin. A silane crosslinked resin molded product comprising the silane crosslinkable resin composition according to any one of claims 1 to 4. 6 . A wiring material comprising the silane crosslinked resin molded article according to claim 5 as a covering layer.

7. A method for producing a silane crosslinkable resin composition, comprising the step (1) of melt-mixing 2 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of undergoing a grafting reaction with the base resin, 1 to 60 parts by mass of a compound having two or more imide structures, 1 to 200 parts by mass of an inorganic filler, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.01 to 5 parts by mass of a silanol condensation catalyst with respect to 100 parts by mass of a base resin comprising a polyolefin resin, to obtain a silane crosslinkable resin composition, wherein: When the step (1) is performed, if all the base resin is melt-mixed in the step (a), the step (1) comprises the steps (a) and (c). On the other hand, if a part of the base resin is melt-mixed in the step (a), the step (1) comprises the steps (a), (b), and (c). Step (a): melt-mixing all or part of the base resin, the inorganic filler, the silane coupling agent, and the organic peroxide at a temperature not lower than the decomposition temperature of the organic peroxide to prepare a silane masterbatch; Step (b): melt-mixing the remaining portion of the base resin and the silanol condensation catalyst to prepare a catalyst masterbatch; Step (c): a step of melt-mixing the silane masterbatch and the silanol condensation catalyst or the catalyst masterbatch, The compound having two or more imide structures is mixed in at least one of the steps (a) and (b).

8. The method for producing a silane crosslinkable resin composition according to claim 7, wherein In the step (b), the entire amount of the compound having two or more imide structures is mixed.

9. A method for producing a silane crosslinked resin molded body, comprising the steps (1), (2), and (3), wherein: Step (1): melt-mixing 2 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of grafting with the base resin, 1 to 60 parts by mass of a compound having two or more imide structures, 1 to 200 parts by mass of an inorganic filler, 0.01 to 0.6 parts by mass of an organic peroxide, and 0.01 to 5 parts by mass of a silanol condensation catalyst with respect to 100 parts by mass of a base resin comprising a polyolefin resin to obtain a mixture; Step (2): forming the mixture obtained in step (1) to obtain a formed body; Step (3): a step of contacting the molded body obtained in step (2) with water to obtain a silane crosslinked resin molded body, When the step (1) is performed, if all the base resin is melt-mixed in the step (a), the step (1) comprises the steps (a) and (c). On the other hand, if a part of the base resin is melt-mixed in the step (a), the step (1) comprises the steps (a), (b), and (c). Step (a): melt-mixing all or part of the base resin, the inorganic filler, the silane coupling agent, and the organic peroxide at a temperature not lower than the decomposition temperature of the organic peroxide to prepare a silane masterbatch; Step (b): melt-mixing the remaining portion of the base resin and the silanol condensation catalyst to prepare a catalyst masterbatch; Step (c): a step of melt-mixing the silane masterbatch and the silanol condensation catalyst or the catalyst masterbatch, The compound having two or more imide structures is mixed in at least one of the steps (a) and (b).

10. The method for producing a silane crosslinked resin molded body according to claim 9, wherein In the step (b), the entire amount of the compound having two or more imide structures is mixed. 11 . A silane crosslinkable resin composition produced by the production method according to claim 7 or 8 . 12 . A silane crosslinked resin molded body produced by the production method according to claim 9 . 13 . A wiring material comprising the silane crosslinked resin molded article according to claim 12 as a covering layer.

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