Crosslinkable resin composition, crosslinked resin composition, resin molded body, and resin composition kit

Abstract

Provided is a crosslinkable resin composition including: a base resin that includes a polymer having at least one among a hydroxy group and a hydroxy group precursor; and a boron compound, wherein the included quantity of boron atoms per 100 parts by mass of the base resin is 0.019 parts by mass or greater. Also provided are a crosslinked resin composition, a resin molded body including the same, and a resin composition kit having a first agent that includes a polymer having at least one among a hydroxy group and a hydroxy group precursor, and a second agent that includes a boron compound.

Description

Crosslinkable resin composition, crosslinked resin composition, resin molded article, and resin composition kit

[0001] The present invention relates to a crosslinkable resin composition, a crosslinked resin composition, a resin molded article, and a resin composition kit.

[0002] High mechanical properties and chemical resistance are required for wiring materials such as insulated wires, cables, cords, optical fiber cores, or optical fiber cords (optical fiber cables) used in the fields of electrical and electronic equipment and industrial applications. To achieve this, the resin composition that forms the insulating layer of the wiring material is crosslinked. For example, methods for crosslinking resin compositions containing polyolefin resins such as polyethylene include electron beam crosslinking, which involves irradiating the resin composition with an electron beam to cause crosslinking; organic peroxide crosslinking, which involves heating the resin composition after molding to decompose organic peroxides and cause a crosslinking reaction; and silane crosslinking, which involves using a silane coupling agent to crosslink the resin composition.

[0003] Electron beam crosslinking requires special crosslinking equipment such as electron beam generators, which require a significant amount of energy. Furthermore, thin-walled materials are desirable for the crosslinking reaction to proceed sufficiently. Organic peroxide crosslinking uses polymers with glass transition temperatures below the reaction temperature (decomposition temperature) of the organic peroxide, limiting the types of polymers that can be used. On the other hand, silane crosslinking has advantages such as not requiring the special equipment needed for electron beam crosslinking and allowing the crosslinking reaction to be carried out at low energy, and is therefore used in a wide range of fields, including wiring materials (for example, Patent Documents 1 and 2).

[0004] Japanese Patent No. 2802274 Specification, Japanese Unexamined Patent Publication No. 2001-101928

[0005] Incidentally, in the silane crosslinking method, as described in Patent Documents 1 and 2, a silanol condensation catalyst such as an organotin compound is usually used to promote the hydrolysis reaction and silanol condensation reaction of the alkoxysilyl group of the silane coupling agent. However, as mentioned above, the silane crosslinking method involves sequentially causing and progressing the hydrolysis reaction and the silanol condensation reaction, so it takes time for the crosslinking reaction to proceed and be completed until sufficient mechanical strength and other properties are exhibited. In particular, the time required for the crosslinking reaction to be completed increases as the thickness of the object to be crosslinked (uncrosslinked molded article) increases. Thus, although the silane crosslinking method has many advantages over the electron beam crosslinking method and the organic peroxide crosslinking method, it takes time for the crosslinking reaction to be completed and there are some limitations on the thickness of the object to be crosslinked.

[0006] In recent years, the applications of crosslinked molded products have expanded and diversified, and there has been growing interest in improving productivity and reducing environmental impact. As a result, various crosslinking methods, including the silane crosslinking method, are required to shorten the crosslinking reaction time and to relax or eliminate restrictions on polymer types and crosslinking targets. Furthermore, organotin compounds, which are commonly used as silanol condensation catalysts in the silane crosslinking method, are a cause for concern regarding their impact on the environment and human health, and it is desirable to avoid their use. However, Patent Documents 1 and 2 do not consider the silane crosslinking method from the perspectives mentioned above.

[0007] The present invention aims to provide a crosslinkable resin composition that can rapidly carry out a crosslinking reaction while relaxing the constraints on the polymer and crosslinking target used, and a resin composition kit suitably used in preparing this crosslinkable resin composition. Furthermore, the present invention aims to provide a crosslinkable resin composition obtained by crosslinking the crosslinkable resin composition, and a resin molded article containing the same.

[0008] The inventors of the present invention diligently studied methods for crosslinking resin compositions and discovered that, for crosslinkable resin compositions, by using a boron compound in combination with a base resin containing a polymer having a hydroxyl group or a group convertible to a hydroxyl group (hydroxyl group precursor), and setting the boron atom content to a specific amount, the crosslinking reaction via the hydroxyl group proceeds rapidly regardless of the type of polymer used. Furthermore, they found that this crosslinking reaction proceeds rapidly without being affected by the shape or thickness of the object to be crosslinked (when crosslinking the crosslinkable resin composition). Based on this finding, the inventors conducted further studies and arrived at the present invention.

[0009] In other words, the object of the present invention has been achieved by the following means: <1> A crosslinkable resin composition comprising a base resin containing a polymer having at least one of a hydroxyl group and a hydroxyl group precursor, and a boron compound, wherein the content of boron atoms per 100 parts by mass of the base resin is 0.019 parts by mass or more. <2> The crosslinkable resin composition according to <1>, wherein the boron compound has a B-O bond. <3> The crosslinkable resin composition according to <1> or <2>, wherein the boron compound is any of boric acid, boronic acid, and borate. <4> The crosslinkable resin composition according to any one of <1> to <3>, wherein the polymer contains a structure derived from a silane coupling agent. <5> The crosslinkable resin composition according to <4>, wherein the silane coupling agent has an alkoxysilyl group. <6> A crosslinkable resin composition obtained by crosslinking the crosslinkable resin composition according to any one of <1> to <5> above. <7> The crosslinkable resin composition according to <6>, which has a B-O bond. <8> A resin molded article comprising the crosslinked resin composition described in <6> or <7> above. <9> A resin composition kit comprising a first agent containing a polymer having at least one of a hydroxyl group and a hydroxyl group precursor, and a second agent containing a boron compound.

[0010] The present invention provides a crosslinkable resin composition that can rapidly undergo a crosslinking reaction while relaxing restrictions on the polymer and crosslinking target used, and a resin composition kit suitably used in preparing this crosslinkable resin composition. Furthermore, the present invention provides a crosslinkable resin composition obtained by crosslinking the crosslinkable resin composition, and a resin molded article containing the same. The above and other features and advantages of the present invention will become clearer from the following description.

[0011] In the present invention, when describing the content, physical properties, etc. of components by indicating numerical ranges, if the upper and lower limits of the numerical range are described separately, either upper or lower limit can be appropriately combined to form a specific numerical range. On the other hand, when multiple numerical ranges expressed using "~" are set and described, the upper and lower limits forming the numerical range are not limited to a specific combination of the upper and lower limits described before and after "~" as a specific numerical range, but can be a numerical range formed by appropriately combining the upper and lower limits of each numerical range. In the present invention, a numerical range expressed using "~" means a range that includes the values ​​described before and after "~" as the lower and upper limits. Also, in the present invention, "(meth)acrylic" represents either acrylic or methacrylic, or both. For example, "(meth)acrylic acid ester" represents either acrylic acid ester or methacrylic acid ester, or both.

[0012] [[Crosslinkable Resin Composition]] The crosslinkable resin composition of the present invention contains a base resin containing a polymer having at least one of a hydroxyl group and a hydroxyl group precursor, and a boron compound, wherein the content of boron atoms per 100 parts by mass of the base resin is 0.019 parts by mass or more. In the crosslinkable resin composition of the present invention, the crosslinking reaction of the polymer having at least one of a hydroxyl group and a hydroxyl group precursor (also referred to as "crosslinkable polymer" in the present invention) occurs and proceeds rapidly from the time of melt kneading, and the crosslinking reaction is completed, for example, within 6 hours (preferably within 1 hour) after the end of melt kneading. In the present invention, when a wiring material having a coating layer formed using the crosslinkable resin composition of the present invention is continuously manufactured, for example, by winding it up with a winding machine, the time for the crosslinking reaction to be completed can be the time described above, but it is also desirable to use the time until it is wound up with a winding machine.

[0013] In the present invention, the starting point of "after melt mixing is completed" refers to the time at which melt mixing has been performed for the minimum time necessary to prepare the crosslinkable resin composition of the present invention as a uniform composition. The minimum time necessary is not uniquely determined, depending on the performance and capacity of the melt mixer, the composition of the crosslinkable resin composition of the present invention, etc. Furthermore, "completion of the crosslinking reaction" refers to the state in which the gel fraction G1 within 6 hours after the completion of melt mixing (or the time until winding in the preferred embodiment described above) reaches a value that approximates the theoretical maximum value (also called the saturation value) of the gel fraction calculated based on the amount of hydroxyl groups etc. of the crosslinkable polymer and the amount of boron compound used. Specifically, as shown in the examples described later, it refers to the state in which the gel fraction G1 reaches a value equivalent to 90% of the gel fraction G2 after 7 days have elapsed since the completion of melt mixing. The environment during the 7-day period is not particularly limited and can be either the humid heat conditions (accelerating conditions: temperature 60°C, relative humidity 95%) or atmospheric conditions (temperature 25°C, relative humidity 50%) adopted in Example A described later. In the present invention, the gel fraction ratio [(G1 / G2) × 100] is preferably 95% or more, and more preferably 98% or more. Ideally, the upper limit of this ratio is 100%. Here, the "theoretical maximum value of the gel fraction" can be calculated as appropriate, but it can also be the same as the gel fraction G2 after 7 days have elapsed since the end of melt mixing. In the present invention, the gel fractions G1 and G2 are not uniquely determined by the amount of hydroxyl groups of the crosslinkable polymer and the amount of boron compound used, respectively. For example, the gel fraction G1 is preferably 50% or more, and more preferably 60% or more. The gel fraction G2 is preferably 50% or more, and more preferably 60% or more. In the present invention, the gel fraction is the value measured by the method described in the examples later. In the present invention, the crosslinking reaction proceeds from the time of melt mixing, and the crosslinking reaction may be almost completed during melt mixing. The progress and completion of the crosslinking reaction during melt mixing can be easily confirmed by increasing the mixing load (torque during mixing).

[0014] In the crosslinkable resin composition of the present invention, the boron atom content is 0.019 parts by mass or more per 100 parts by mass of the base resin, as described later. This boron atom content enables a rapid crosslinking reaction of the crosslinkable resin composition (crosslinkable polymer) of the present invention. The boron atom content in the crosslinkable resin composition of the present invention is preferably 0.086 parts by mass or more, and more preferably 0.171 parts by mass or more, per 100 parts by mass of the base resin, in order to achieve a rapid crosslinking reaction and improve the gel fraction, thereby realizing excellent mechanical properties. On the other hand, there is no particular upper limit to the boron atom content, but in terms of balancing a rapid crosslinking reaction with excellent mechanical properties, it is preferably 2.85 parts by mass or less, more preferably 1.71 parts by mass or less, and even more preferably 0.494 parts by mass or less, per 100 parts by mass of the base resin. In the present invention, the boron atom content in the crosslinkable resin composition refers to the boron atom content derived from the boron compound described later, and does not include the boron atom content derived from inorganic fillers, etc. Furthermore, the boron atom content in the crosslinkable resin composition is the sum of the content of all boron atoms derived from the boron compound, regardless of their state of existence, if they are boron atoms derived from the boron compound. Therefore, the boron atom content includes the boron atom content in boron compounds (unreacted, undecomposed boron compounds, etc.) that exist independently (free) in the composition, and also the boron atom content when incorporated into the crosslinked structure as described later. The boron atom content in the crosslinkable resin composition of the present invention can be measured by conventional methods, for example, by mass spectrometry, or by energy-dispersive X-ray analysis using a scanning electron microscope or transmission electron microscope to determine the relative abundance of elements present on the sample surface. It can also be calculated from the blending amount during the preparation of the crosslinkable resin composition.

[0015] [[Crosslinked Resin Composition]] The crosslinked resin composition of the present invention is a crosslinked product obtained by crosslinking the crosslinkable resin composition of the present invention. The crosslinked resin composition of the present invention may be in a shapeless (unmolded) bulk state or in a molded state (resin molded article). In the present invention, the term "crosslinked product" usually includes both crosslinked products in bulk state and crosslinked products in molded state, but when distinguishing a crosslinked product in molded state from a crosslinked product in bulk state, it is simply referred to as a resin molded article or a crosslinked resin molded article.

[0016] The crosslinked resin composition of the present invention contains a crosslinked polymer having a crosslinked structure formed by a crosslinking reaction of a hydroxyl group or hydroxyl group precursor of a crosslinkable polymer. While the specific chemical structure of the crosslinked structure of the crosslinked resin composition and crosslinked polymer of the present invention, other than that formed by a crosslinking reaction of a hydroxyl group or hydroxyl group precursor, is not yet clear, it is presumed to have a structure formed by the reaction of a hydroxyl group or hydroxyl group precursor with a boron compound, for example, a -B-O- bond. In particular, if the crosslinkable polymer is a silane graft polymer with a silane coupling agent (described later) grafted onto it, it is presumed to have a structure derived from a silanol condensation-capable reaction site of the silane coupling agent, for example, a structure formed by the reaction of a hydroxyl group (-Si-OH group) with a boron compound (-Si-O-B-), and further a structure containing residues derived from the grafting reaction site of the silane coupling agent (-grafting reaction site residue-Si-O-B-), for example, one or more of the crosslinked structures shown below. The crosslinked resin composition having this crosslinked structure can also be called a boron crosslinked resin composition or a boron-silicon crosslinked resin composition.

[0017] In the example of the crosslinked structure below, the large wavy lines above and below represent the polymer main chain, and the small wavy lines bonded to the Si atoms represent the linking groups that connect the polymer main chain and the Si atoms. These linking groups are residues derived from the grafting reaction site of the silane coupling agent, for example, -CH ２ -CH ２- are examples. In addition, in the example below, a hydroxyl group is bonded to the Si atom, but depending on the type of boron compound used, it may also be an alkyl or aryloxy group, and it may also undergo a silanol condensation reaction with other nearby silanol groups to form a -Si-O-Si- bond, or it may be bonded to an inorganic filler, etc.

[0018]

[0019] The gel fraction in the crosslinked resin composition of the present invention is at least the same as the gel fraction G1 described above, and preferably the same as the gel fraction G2 described above. In the crosslinked resin composition of the present invention, depending on the amount of hydroxyl groups etc. of the crosslinkable polymer and the amount of boron compound used, the boron compound may not participate in the crosslinking reaction and may remain in the crosslinked resin composition as a compound.

[0020] [[Resin Molded Article of the Present Invention]] The resin molded article of the present invention is a resin molded article containing the crosslinked resin composition of the present invention, and is usually a crosslinked resin molded article obtained by molding the crosslinked resin composition of the present invention into a predetermined shape and dimensions. The resin molded article of the present invention is molded into an appropriate shape and dimensions depending on the application, etc. The resin molded article of the present invention is the same as the crosslinked resin composition of the present invention except that it is molded into a predetermined shape and dimensions.

[0021] The resin molded article of the present invention is a resin molded article (including semi-finished products, parts, and components) containing the crosslinked resin composition of the present invention, and can be used as various molded articles. The resin molded article of the present invention may contain the crosslinked resin composition of the present invention in a part (resin molded part), or it may consist only of the crosslinked resin composition of the present invention. The size and shape of the resin molded article of the present invention are not particularly limited, and it can be made into various molded articles such as insulated wires, cables, optical cords, as well as power plugs, connectors, sleeves, boxes, tape substrates, tubes, and sheets. The resin molded article of the present invention is preferably used as a coating layer for wiring materials such as insulated wires, cables, and optical cords. The thickness of the coating layer is not particularly limited, but is preferably 0.15 to 3 mm. The coating layer may have a multilayer structure. Wiring materials such as insulated wires and cables can be manufactured by extruding the crosslinkable resin composition of the present invention or a crosslinked resin composition around conductors, optical fibers, bundled insulated wires, and other molded articles using a conventional extrusion molding machine. As described above, the coating layer formed with the crosslinked resin composition of the present invention has a crosslinked structure (B-O bond) containing boron atoms, and preferably a silane crosslinked structure (-Si-O-B- bond) via boron atoms. The crosslinkable resin composition, crosslinked resin composition, and resin molded article of the present invention used for forming the coating layer of wiring material are referred to as the coating crosslinkable resin composition, coating crosslinked resin composition, and coating resin molded article, respectively.

[0022] [[Resin Composition Kit]] The resin composition kit of the present invention is a kit of agents used to prepare the crosslinkable resin composition of the present invention, comprising a first agent (main agent) containing a polymer having at least one of a hydroxyl group and a hydroxyl group precursor, and a second agent (crosslinking contributing agent) containing a boron compound. The resin composition kit of the present invention is a crosslinkable kit. In addition to the above polymer, the first agent may contain other polymers, inorganic fillers, plasticizer components, additives, etc., as described later. However, it is preferable that it does not contain a boron compound and / or a silanol condensation catalyst. The second agent may contain a boron compound as described later, and may also contain other polymers, inorganic fillers, silanol condensation catalysts, plasticizer components, additives, a solvent for dissolving the boron compound, etc., as described later. The second agent is preferably an agent containing a boron compound alone, or an agent containing a boron compound and other polymers. The content of each component in the first agent and the second agent is not particularly limited and can be determined as appropriate, for example, it can be the content of each component in the crosslinkable resin composition described later. The resin composition kit of the present invention may also have a third agent containing at least one of the following: other polymers, inorganic fillers, plasticizer components, additives, etc.

[0023] The resin composition kit of the present invention can be used to prepare the crosslinkable resin composition of the present invention by appropriately determining the amounts of the first agent and the second agent to be used, taking into consideration the content of boron atoms in the crosslinkable resin composition and the content of boron compounds in the crosslinkable resin composition described later.

[0024] The components used in this invention are described below. Each component can be used individually or in combination of two or more types.

[0025] [Base Resin] The base resin used in the present invention may contain a polymer having at least one of a hydroxyl group and a hydroxyl group precursor (crosslinkable polymer), and may also contain polymers other than this crosslinkable polymer (referred to as other polymers). The crosslinkable polymer may be a polymer in which the polymer itself has at least one of a hydroxyl group and a hydroxyl group precursor (in the present invention, this may be conveniently referred to as a "hydroxy polymer"), or it may be a polymer having at least one of a hydroxyl group and a hydroxyl group precursor as a substituent or modifying group (in the present invention, this may be conveniently referred to as a "modified polymer"). The crosslinkable polymer is preferably a modified polymer in terms of the handling properties of the crosslinkable resin composition and the mechanical properties of the crosslinkable resin composition, and it is more preferably a polymer containing a structure derived from a silane coupling agent described later, for example, a silane graft polymer described later.

[0026] In the present invention, the term "hydroxyl group" usually refers to an -OH group, but it also includes salts of -OH groups and groups containing an -OH group. Examples of groups containing an -OH group include -OH groups bonded to heteroatoms, specifically Si-OH groups (silanol groups). Furthermore, a hydroxyl group precursor refers to a group that can generate a hydroxyl group or convert to a hydroxyl group, such as a group that generates a hydroxyl group through hydrolysis reactions, more specifically, an alkoxy group, an aryloxy group, a (mono, di, or tri)alkoxysilyl group, a (mono, di, or tri)aryloxysilyl group, and the like.

[0027] The hydroxyl group and hydroxyl group precursor of the crosslinkable polymer are preferably hydroxyl group precursors, more preferably alkoxysilyl groups, and even more preferably trialkoxysilyl groups. The number of types of hydroxyl groups and hydroxyl group precursors of the crosslinkable polymer is not particularly limited and may be one type or two or more types. In the present invention, depending on the properties to be expressed in the crosslinkable resin composition or resin molded article of the present invention, one type of crosslinkable polymer having one type of hydroxyl group or hydroxyl group precursor may be used, one type of crosslinkable polymer having multiple types of hydroxyl groups and / or hydroxyl group precursors may be used, furthermore, multiple types of crosslinkable polymers having one type of hydroxyl group or hydroxyl group precursor may be used (the type of hydroxyl group or hydroxyl group precursor may be the same or different for each crosslinkable polymer), or multiple types of crosslinkable polymers having multiple types of hydroxyl groups and / or hydroxyl group precursors may be used. The number of hydroxyl groups and hydroxyl group precursors of the crosslinkable polymer is not particularly limited and can be appropriately determined, for example, depending on the content of boron compounds. For example, the number of hydroxyl groups and hydroxyl group precursors can be 2 to 300 on average per molecule of crosslinkable polymer, preferably 2 to 20, and more preferably 5 to 20. The number of hydroxyl groups and hydroxyl group precursors present in a crosslinkable polymer can be calculated, for example, from the molecular weight of the crosslinkable polymer.

[0028] The crosslinkable polymer may be an elastomer (including rubber), but from the viewpoint of the properties of the crosslinked resin composition, such as mechanical properties, it is preferable that it be a resin.

[0029] <Hydroxypolymer> The hydroxypolymer is not particularly limited, but examples include polyvinyl alcohol (PVA), saponified ethylene vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyglycerol methacrylate, polymers having a diethanolamine skeleton, epoxy resins, etc. In one embodiment of the present invention, the hydroxypolymer may be a hydroxypolymer other than polyvinyl alcohol, a hydroxypolymer other than epoxy resin, or a hydroxypolymer other than polyvinyl alcohol and other than epoxy resin. Commercially available hydroxypolymers can also be used. For example, commercially available saponified ethylene vinyl acetate copolymers include Mersen® H-6051K, Mersen® H-6410M, Mersen® H-3051R, Mersen® H-6820, and Mersen® H-6822X (all trade names, manufactured by Tosoh Corporation). Commercially available ethylene-vinyl alcohol copolymers include, for example, EVAL G156B and EVAL L171B (both trade names, manufactured by Kuraray Co., Ltd.).

[0030] <Modified Polymers> Modified polymers only need to have at least one of a hydroxyl group and a hydroxyl group precursor as a substituent or modifying group. Examples include polymers containing components derived from monomers having a hydroxyl group or a hydroxyl group precursor, and polymers in which a compound having a hydroxyl group or a hydroxyl group precursor is substituted in the main chain. The polymer that forms the modified polymer (the polymer before the introduction of the hydroxyl group and the hydroxyl group precursor) is not particularly limited, and examples include polymers having a site in the main chain or at its end that can react with a compound having a hydroxyl group or a hydroxyl group precursor, preferably a polymer having a site in the main chain or at its end that can react with a grafting site for a silane coupling agent in the presence of an organic peroxide. Examples of sites that can react with grafting include unsaturated bond sites in a carbon chain and carbon atoms having hydrogen atoms. Examples of such polymers include thermoplastic elastomers, ethylene copolymer resins, modified polyethylene resins, polyolefin resins, polyester resins, and various rubbers. In addition to these, chlorine-containing resins (resins specified in JIS K 7229-1995) and fluorine-containing resins such as fluororubber can also be used.

[0031] Thermoplastic elastomers are not particularly limited, but examples include polyester elastomers, styrene elastomers, polyurethane elastomers, olefin elastomers, and polyamide elastomers.

[0032] Although not particularly limited, examples of the resin of the ethylene-based copolymer include resins of ethylene-α-olefin copolymers, polyolefin copolymers having an acid copolymerization component or an acid ester copolymerization component. Specifically, examples include resins such as ethylene-vinyl acetate copolymers (non-saponified products), ethylene-(meth)acrylic acid copolymers, and ethylene-(meth)acrylic acid alkyl copolymers. As the modified polyethylene resin, for example, those obtained by modifying the above-mentioned resin of the ethylene-based copolymer may be used. For example, resins of ethylene-vinyl acetate copolymers modified with polyorganosiloxane, polyolefin resins or polyethylene resins modified with unsaturated carboxylic acids, resins of ethylene-vinyl acetate copolymers modified with unsaturated carboxylic acids, resins of ethylene-(meth)acrylic acid ester copolymers modified with unsaturated carboxylic acids, and the like can be mentioned.

[0033] The polyolefin resin is a polymer obtained by polymerizing or copolymerizing a compound having an ethylenically unsaturated bond, and is not particularly limited as long as it is a resin of a polymer other than the above-mentioned resin of the ethylene-based copolymer and other than the above-mentioned resin of the modified polyethylene, and those conventionally used in resin compositions can be used. For example, resins such as polyethylene and polypropylene can be mentioned, and polyethylene is particularly preferred. Polyethylene is not particularly limited, and examples include high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, linear low-density polyethylene, ultra-low density polyethylene, and the like. Among them, linear low-density polyethylene and low-density polyethylene are preferred. Polypropylene is not particularly limited, and examples include homopolymers of propylene, random polypropylene, and block polypropylene.

[0034] The polyester resin is not particularly limited, and examples include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), and the like.

[0035] Although the rubber is not particularly limited, examples thereof include ethylene rubber, acrylic rubber, nitrile rubber, and styrene rubber. Specific examples of the ethylene rubber include ethylene-propylene rubber, ethylene-butene rubber, ethylene-octene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, and the like.

[0036] (Silane graft polymer) As the crosslinkable polymer, a modified polymer is preferable, and a polymer obtained by grafting a silane coupling agent described later (silane graft polymer) is more preferable. As the silane graft polymer, a polymer having a structure derived from the silane coupling agent and having a site capable of the above-described graft reaction is preferably a silane graft polyolefin resin obtained by grafting a silane coupling agent to a polyolefin resin, and more preferably a silane graft polyethylene resin obtained by grafting a silane coupling agent to a polyethylene resin. The silane graft polymer can usually be synthesized by subjecting a polymer having a site capable of the graft reaction to a graft reaction with a silane coupling agent using a thermal radical initiator (organic peroxide).

[0037] - Silane Coupling Agents - Silane coupling agents have graft reaction sites (or functional groups such as ethylenically unsaturated groups) that react with grafts in the presence of radicals generated by the decomposition of organic peroxides. Silane coupling agents also have reaction sites that can undergo silanol condensation (including sites produced by hydrolysis, such as silyl ester groups). Examples of such silane coupling agents include those conventionally used in silane crosslinking methods, and silane coupling agents having ethylenically unsaturated groups and hydrolyzable silyl groups are preferred. Examples of hydrolyzable silyl groups include alkoxysilyl groups and aryloxysilyl groups as described above in the section on hydroxyl group precursors, and (di or tri)alkoxysilyl groups are preferred. Examples of silane coupling agents include vinylsilanes such as vinyltrimethoxysilane (VTMS), vinyltriethoxysilane (VTES), vinyltributoxysilane, vinyldimethoxyethoxysilane, vinyldimethoxybutoxysilane, vinyldiethoxybutoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and vinyltriacetoxysilane, and (meth)acryloxysilanes such as methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, and methacryloxypropylmethyldimethoxysilane. A single silane coupling agent may be used alone, or two or more may be used in combination. Furthermore, they may be used as is, or diluted with a solvent or the like.

[0038] - Organic peroxide - The organic peroxide generates radicals at least by thermal decomposition and functions as a catalyst to cause a grafting reaction (a covalent bond formation reaction between the grafting reaction site of the silane coupling agent and the graftable site of the polymer) by a radical reaction of the silane coupling agent with the polymer. Particularly when the reaction site of the silane coupling agent contains, for example, an ethylenically unsaturated group, it functions to cause a grafting reaction by a radical reaction between the ethylenically unsaturated group and the polymer (including a reaction of extracting a hydrogen radical from the polymer). There is no particular limitation on the organic peroxide. For example, compounds represented by the general formula: R １ -OO-R ２ , R ３ -OO-C(=O)R ４ , R ５ C(=O)-OO(C=O)R ６ are preferred. Here, R １ to R ６ each independently represent an alkyl group, an aryl group or an acyl group. R １ to R ６Of these, those in which all are alkyl groups, or those in which one is an alkyl group and the rest is an acyl group, are preferred. Examples of such organic peroxides include dicumyl peroxide (DCP), di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyn-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butylcumyl peroxide. Of these, dicumyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyn-3 are preferred in terms of odor, color, and scorch stability. The decomposition temperature (exothermic onset temperature) of the organic peroxide under normal pressure (approximately 0.1 MPa) is preferably 80 to 195°C, and particularly preferably 125 to 180°C. In the present invention, the decomposition temperature of the organic peroxide means the temperature at which, when a single-composition organic peroxide is heated, it undergoes a decomposition reaction into two or more compounds at a certain temperature or temperature range. Specifically, it refers to the temperature at which endothermic or exothermic reactions begin when heated from room temperature at a heating rate of 5°C / min under a nitrogen gas atmosphere, as determined by thermal analysis such as the DSC method.

[0039] In the grafting reaction of a silane coupling agent in the presence of an organic peroxide (hereinafter sometimes simply referred to as the grafting reaction), the amount of silane coupling agent used is not particularly limited, but is preferably an amount equal to the amount of hydroxyl groups present in the crosslinkable polymer. Specifically, in terms of imparting excellent properties to the crosslinked resin composition of the present invention, it is more preferably 1 to 40 parts by mass, even more preferably 2 to 30 parts by mass, particularly preferably 2 to 25 parts by mass, and most preferably 2 to 5 parts by mass, per 100 parts by mass of the polymer to be grafted. In the grafting reaction, the amount of organic peroxide used is not particularly limited, but for example, in terms of efficiently causing and proceeding the grafting reaction of the silane coupling agent, it is preferably 0.01 to 1.0 parts by mass, more preferably 0.05 to 0.8 parts by mass, and even more preferably 0.1 to 0.6 parts by mass, per 100 parts by mass of the polymer to be grafted.

[0040] The reaction conditions for the grafting reaction are not particularly limited, and conventional reaction conditions for grafting reactions can be applied. Typically, melting and kneading conditions at a temperature above the decomposition temperature of the organic peroxide are used. Specifically, the heating temperature is preferably 140 to 230°C, but can also be 175 to 210°C.

[0041] The silane graft polymer obtained as described above can also be a commercially available product such as Linkron (trade name, manufactured by Mitsubishi Chemical Corporation).

[0042] <Other Polymers> Other polymers that may be included in the base resin are not particularly limited, as long as they are polymers that do not correspond to crosslinkable polymers, and polymers that do not have hydroxyl groups and hydroxyl group precursors (non-crosslinkable polymers). Examples of non-crosslinkable polymers include the various polymers mentioned above that form modified polymers, and among these, ethylene copolymer resins and polyolefin resins are preferred.

[0043] (Composition of base resin) In the present invention, the content of the crosslinkable polymer in the base resin is not particularly limited, but it can be 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more, in terms of the crosslinking reaction of the crosslinkable resin composition of the present invention and the properties of the crosslinkable resin composition of the present invention. On the other hand, the upper limit of the crosslinkable polymer content is preferably 100% by mass, but it can also be 95% by mass or less, or 90% by mass or less. In the present invention, when synthesizing a crosslinkable polymer, the mass of the crosslinkable polymer is, for convenience, the total mass of each component (raw material) that forms the crosslinkable polymer. For example, when synthesizing a silane graft polymer as a crosslinkable polymer, the mass of the silane graft polymer is the total mass of the polymer to be grafted and the silane coupling agent (before the grafting reaction, i.e., the amount used), regardless of the grafting rate of the silane coupling agent.

[0044] When the crosslinkable resin composition of the present invention contains two or more crosslinkable polymers, the content of each crosslinkable polymer is not particularly limited and can be determined as appropriate. For example, when a hydroxy polymer and a modified polymer are used in combination, it is preferable that the content of the modified polymer is greater than the content of the hydroxy polymer, and the mass ratio of the content of the modified polymer to the content of the hydroxy polymer [content of modified polymer / content of hydroxy polymer] can be 2 to 35, and is preferably 2 to 15.

[0045] The content of other polymers in the base resin is not particularly limited, but is preferably 0 to 30% by mass, and can also be 10 to 20% by mass, in terms of the crosslinking reaction of the crosslinkable resin composition of the present invention and the properties of the crosslinkable resin composition of the present invention.

[0046] [Boron Compounds] The boron compounds used in the present invention may be any compounds containing boron atoms, and it is preferable that they have a B-O bond (-B-O-) in that they allow the crosslinking reaction to occur rapidly. Furthermore, in that the crosslinking reaction can be completed quickly, the boron compounds are preferably boron compounds (also called reactive boron compounds) that have a reactive group that reacts with a hydroxyl group or hydroxyl group precursor of the crosslinkable polymer. The reactive group is not particularly limited, but can be appropriately selected depending on the reaction mechanism with the hydroxyl group or hydroxyl group precursor. For example, a hydroxyl group that undergoes a dehydration condensation reaction with a hydroxyl group, an alkoxy group or aryloxy group that undergoes a transesterification reaction (including a dehydration condensation reaction after hydrolysis) with a hydroxyl group, or a group described above as a hydroxyl group precursor of the crosslinkable polymer (excluding hydroxyl groups, alkoxy groups and aryloxy groups), and further, a structure that gives a B-O-H group after hydrolysis, such as the 4,4,5,5-tetramethyl-1,3,2-dioxaborolane structure (for example, a cyclic boronic acid ester in which boronic acid is protected with a diol). The reactive group is preferably a hydroxyl group because it allows the crosslinking reaction to be completed quickly. The hydroxyl group may also form a salt. The number of types of reactive groups that a single molecule of boron compound may have is not particularly limited. The number of reactive groups that a single molecule of boron compound may have is not particularly limited, and may be one or more, but it is preferable to have two or more, and more preferably two to four, in that they can contribute to the formation of the crosslinking structure.

[0047] As described above, when a boron compound is incorporated into a crosslinked structure to form a crosslinked structure, the boron compound can also be called a crosslinking agent. The boron compounds used in the present invention, particularly boron compounds as crosslinking agents (reactive boron compounds), differ from boron compounds as inorganic fillers such as aluminum borate, boron nitride, and zinc borate, as shown in the above example of the estimated structure of the crosslinked structure, in that they have one or more, preferably two or more, reactive groups. In this respect, the boron compounds used in the present invention can be said to be compounds other than boron compounds as inorganic fillers, for example, compounds other than aluminum borate, compounds other than boron nitride, and compounds other than zinc borate.

[0048] The boron compound is not particularly limited as long as it is a compound that contributes to the occurrence and promotion of the crosslinking reaction, but compounds having the above-mentioned bond or reactive group are preferred, and although it may be a high molecular weight compound (polymer), it is preferable that it be a low molecular weight compound (non-polymerizable compound). Examples of boron compounds include boric acid, borate, boronic acid, borate ester, and boronic acid ester. These compounds may be anhydrous or hydrated. Boric acid includes orthoboric acid and tetraboric acid, and orthoboric acid is preferred because it can complete the crosslinking reaction quickly. Examples of borates include Na ２ B ４ O ５ (OH) ４ 8H ２ O, Na ２ B ４ O ７ _K ２ B ４ O ７ 4H ２ Examples include O. Examples of boronic acids include alkylboronic acids such as methylboronic acid, phenylboronic acid, and arylboronic acids such as 1,4-phenylenediboronic acid, with 1,4-phenylenediboronic acid being preferred because it allows the crosslinking reaction to be completed quickly. Examples of boric acid esters and boronic acid esters include alkyl esters or aryl esters of each. Among the above compounds, the boron compound is preferably boric acid, borate, or boronic acid, more preferably boric acid or boronic acid, and even more preferably boric acid, because it allows the crosslinking reaction to be completed quickly.

[0049] [Inorganic Filler] The crosslinkable resin composition of the present invention may contain an inorganic filler (except for the boron compounds mentioned above). The inorganic filler is not particularly limited and includes, for example, metal hydrates such as compounds having hydroxyl groups or crystal water, such as aluminum hydroxide, magnesium hydroxide, boehmite, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, hydrated aluminum silicate, hydrated magnesium silicate, basic magnesium carbonate, hydrotalcite, and talc. Other examples include boron nitride, silica (crystalline silica, amorphous silica, etc.), carbon black, clay (calcined clay), zinc oxide, tin oxide, titanium oxide, molybdenum oxide, antimony trioxide, silicone compounds, quartz, zinc borate, white carbon, zinc borate, zinc hydroxystannate, and zinc stannate. The inorganic filler may be surface-treated. For example, a surface-treated inorganic filler treated with a silane coupling agent can be used. Examples of inorganic fillers used for surface treatment of silane coupling agents include Kisma 5L, Kisma 5P (both trade names, magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd., etc.), and FK621 (trade name, magnesium hydroxide, manufactured by Kamishima Chemical Industry Co., Ltd.). The inorganic filler is preferably at least one selected from the group consisting of silica, aluminum hydroxide, magnesium hydroxide, and calcium carbonate. One type of inorganic filler may be used alone, or two or more types may be used in combination.

[0050] [Plasticizer Component] The crosslinkable resin composition of the present invention may contain at least one of a plasticizer and an oil as a plasticizer component. The oil is not particularly limited, but examples include organic oils and mineral oils. Examples include soybean oil, paraffin oil, naphthenic oil, and aromatic oil. Among these, soybean oil, paraffin oil, and naphthenic oil are preferred. Examples of plasticizers include various types commonly used in polyvinyl chloride. Examples include trialkyl trimellitic acid (C8, C10), pyromellitic acid ester plasticizers, phthalate ester plasticizers, adipic acid ester plasticizers, polyester plasticizers, etc.

[0051] [Silanol Condensation Catalyst] The crosslinkable resin composition of the present invention may contain a silanol condensation catalyst to promote the dehydration condensation of silanol condensation reaction sites, such as silane coupling agents, particularly between hydrolyzable silyl groups. The silanol condensation catalyst has the function of causing a condensation reaction of a silane coupling agent grafted to the crosslinkable polymer in the presence of water. The silanol condensation catalyst used in the present invention is not particularly limited and examples include organotin compounds, metal soaps, platinum compounds, etc. Examples of common silanol condensation catalysts include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctiate, dibutyltin diacetate, zinc stearate, lead stearate, barium stearate, calcium stearate, sodium stearate, lead naphthenate, lead sulfate, zinc sulfate, organoplatin compounds, etc. From the viewpoint of promoting the silanol condensation reaction, the silanol condensation catalyst is preferably an organotin compound, and more preferably dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctiate, dibutyltin diacetate, etc. On the other hand, from the viewpoint of avoiding impacts on the environment and human health, compounds other than organotin compounds are preferred. The silanol condensation catalyst is optionally mixed with a resin and used. The resin (also called the carrier resin) is not particularly limited, but any of the resins or rubbers described in the base resin section can be used.

[0052] [Additives] The crosslinkable resin composition of the present invention may contain various commonly used additives to the extent that they do not impair the effects of the present invention. Examples of such additives include crosslinking aids, antioxidants, lubricants, metal deactivators, flame retardants, flame retardant aids, and the like.

[0053] <Crosslinking Aids> Crosslinking aids are substances that form a partially crosslinked structure with a crosslinked polymer in the presence of an organic peroxide. Examples include (meth)acrylate compounds such as polypropylene glycol diacrylate and trimethylolpropane triacrylate, allyl compounds such as triallyl cyanurate, maleimide compounds, and divinyl compounds. It is preferable that the crosslinked structure formed by the crosslinking aid is formed separately from the crosslinked structure formed by the hydroxyl group or hydroxyl group precursor of the crosslinkable polymer.

[0054] <Antioxidants> Antioxidants are not particularly limited, but examples include amine antioxidants, phenol antioxidants, or sulfur antioxidants. Examples of amine antioxidants include 4,4'-dioctyldiphenylamine, N,N'-diphenyl-p-phenylenediamine, and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline. Examples of phenol antioxidants include pentaerythrityl-tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene. Examples of sulfur antioxidants include bis(2-methyl-4-(3-n-alkylthiopropionyloxy)-5-tert-butylphenyl) sulfide, 2-mercaptobenzimidazole and its zinc salt, and pentaerythritol-tetrakis(3-lauryl-thiopropionate).

[0055] <Lubricants> Lubricants are not particularly limited, but examples include hydrocarbon-based, siloxane-based, fatty acid-based, fatty acid amide-based, ester-based, alcohol-based, and metal soap-based lubricants.

[0056] <Metal deactivators> Metal deactivators are not particularly limited, but examples include N,N'-bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl)hydrazine, 3-(N-salicyroyl)amino-1,2,4-triazole, and 2,2'-oxamidobis(ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate).

[0057] <Flame retardants and flame retardant additives> Examples of flame retardants and flame retardant additives include halogenated flame retardants such as polychlorinated biphenyls and chlorendic acid.

[0058] [Composition of the Crosslinkable Resin Composition] The content of the boron compound in the crosslinkable resin composition is appropriately determined considering the content of the boron atoms described above. The content of the boron compound is preferably 0.10 to 20.0 parts by mass, more preferably 0.40 to 10.0 parts by mass, and even more preferably 0.90 to 3.0 parts by mass, per 100 parts by mass of the base resin, in order to quickly complete the crosslinking reaction.

[0059] The amount of inorganic filler in the crosslinkable resin composition is not particularly limited. For example, it can be 0 parts by mass or more per 100 parts by mass of the base resin. In terms of heat resistance and mechanical properties, it is more preferably 10 to 400 parts by mass, even more preferably 10 to 300 parts by mass, and particularly preferably 10 to 200 parts by mass. In this invention, the amount of inorganic filler can be determined as appropriate. For example, it can be less than 10 parts by mass per 100 parts by mass of the base resin.

[0060] The total content of plasticizer components in the crosslinkable resin composition is not particularly limited, but is preferably 0 to 80 parts by mass, more preferably 0 to 60 parts by mass, and even more preferably 0 to 30 parts by mass, per 100 parts by mass of the base resin.

[0061] In the crosslinkable resin composition, the content of the silanol condensation catalyst is preferably 0 to 0.5 parts by mass, and more preferably 0 to 0.3 parts by mass, per 100 parts by mass of the base resin, in order to construct a crosslinked structure through the condensation reaction of silane coupling agents.

[0062] The content of the crosslinking aid in the crosslinkable resin composition is not particularly limited, but for example, it is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 30 parts by mass, and even more preferably 0.1 to 15 parts by mass per 100 parts by mass of the base resin. The content of the antioxidant in the crosslinkable resin composition is not particularly limited, but for example, it is preferably 0.1 to 15.0 parts by mass, and more preferably 0.1 to 10 parts by mass per 100 parts by mass of the base resin. The content of the lubricant in the crosslinkable resin composition is not particularly limited, but for example, it is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and even more preferably 0.1 to 10 parts by mass per 100 parts by mass of the base resin. The content of metal deactivators in the crosslinkable resin composition is not particularly limited, but is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the base resin. The total content of flame retardants and flame retardant aids in the crosslinkable resin composition is not particularly limited, but is preferably 10 to 400 parts by mass, more preferably 10 to 300 parts by mass, and even more preferably 10 to 200 parts by mass, per 100 parts by mass of the base resin.

[0063] [Composition of Crosslinked Resin Composition and Resin Molded Article] Since the crosslinked resin composition and resin molded article of the present invention are formed by crosslinking the crosslinkable resin composition of the present invention, the types and content of each component in the crosslinked resin composition and resin molded article are usually the same as the types and content of each component in the crosslinkable resin composition of the present invention. The content of boron atoms in the crosslinked resin composition and resin molded article is also the same. However, the silanol condensation catalyst usually decomposes and disappears. In addition, the boron compound may be incorporated into the crosslinked structure, in which case the content of the boron compound in the crosslinked resin composition and resin molded article is less than the content of the boron compound in the crosslinkable resin composition, and cannot be uniquely determined by variations in the number of hydroxyl groups, etc. of the crosslinkable polymer, the content of the boron compound in the crosslinkable resin composition, etc. If the boron compound is contained in excess relative to the number of hydroxyl groups, etc. of the crosslinkable polymer in the crosslinkable resin composition, the boron compound may remain in the crosslinked resin composition and resin molded article as unreacted or undecomposed material. If inorganic fillers are included, they may be incorporated into the crosslinked structure, and the inorganic filler content shall be calculated based on the content before incorporation into the crosslinked structure. The base resin content shall also be calculated based on the content before crosslinking.

[0064] [[Method for Producing Crosslinkable Resin Composition]] The crosslinkable resin composition of the present invention is not particularly limited, but for example, it can be prepared by blending each component in a blender in a mixing ratio that satisfies the composition of the above crosslinkable resin composition, and then melt-kneading it in a commonly used kneading device such as a single-screw extruder, twin-screw extruder, Banbury mixer, kneader, or roll. The melt-kneading temperature is not particularly limited, but 150 to 240°C is preferred. The melt-kneading time can be the minimum time necessary to prepare each component into a uniform composition, for example, several minutes to several hours. The mixing order of each component is not particularly limited. When using an inorganic filler, it is preferable to pre-mix the inorganic filler with a silane coupling agent, as this allows for the construction of a crosslinked structure containing the inorganic filler and a crosslinked structure without the inorganic filler, resulting in a crosslinkable resin composition and resin molded article exhibiting excellent physical properties. The crosslinkable resin composition of the present invention can also be appropriately pelletized and prepared as pellets.

[0065] When a silane graft polymer is used as the crosslinkable polymer, the following methods 1 to 4 are listed as specific methods for producing the crosslinkable resin composition, but are not limited to these and can be modified as appropriate. When an inorganic filler is used, the timing of mixing the inorganic filler in the following methods 1 to 4 is not particularly limited, but it is preferable to mix it with the silane coupling agent in advance when preparing the silane graft polymer. Method 1: First, the components for preparing the silane graft polymer are melt-kneaded to prepare the silane graft polymer (prepare the base resin), and then (continuously) a boric acid compound, etc., is added and melt-kneaded, and pelletized as appropriate to produce the crosslinkable resin composition of the present invention. Method 2: The components for preparing the silane graft polymer are melt-kneaded to prepare the silane graft polymer (prepare the crosslinkable polymer), and pelletized as appropriate to prepare compound A. Separately, a non-crosslinkable polymer and a boron compound are melt-kneaded and pelletized as appropriate to prepare compound B. Next, compound A and compound B are melt-kneaded to produce the crosslinkable resin composition of the present invention. Method 3: Prepare a silane graft polymer (prepare a crosslinkable polymer) by melt-kneading the components for preparing the silane graft polymer, and pelletize it as appropriate to prepare compound A. After dry-blending compound A and a boron compound, melt-knead them (using an extruder, etc.) to produce the crosslinkable resin composition of the present invention (in an extruder). The conditions for dry blending are not particularly limited as long as it is dry mixing, but for example, conditions include mixing at 10 to 60°C (preferably near room temperature (20 to 25°C)) for several minutes to several hours. Method 4: Prepare a silane graft polymer (prepare a crosslinkable polymer) by melt-kneading the components for preparing the silane graft polymer, and pelletize it as appropriate to prepare compound A. A method for producing the crosslinkable resin composition of the present invention by introducing compound A into, for example, a twin-screw extruder and melt-kneading it with a boron compound in the twin-screw extruder (in the twin-screw extruder).

[0066] [[Method for Manufacturing the Crosslinked Resin Composition]] Since the crosslinking reaction of the crosslinkable resin composition of the present invention proceeds rapidly, the crosslinking reaction may be completed while the crosslinkable polymer and the boron compound are melt-kneaded in the method for manufacturing the crosslinkable resin composition of the present invention. In this case, the crosslinkable resin composition of the present invention can be manufactured during melt-kneading or upon completion of melt-kneading. Even if the crosslinking reaction is not completed while the crosslinkable polymer and the boron compound are melt-kneaded, the crosslinking reaction will proceed rapidly thereafter, and the crosslinking reaction may be completed within 6 hours (preferably within 1 hour, and even more preferably within the time until winding in the above preferred embodiment) after the completion of melt-kneading, thereby manufacturing the crosslinkable resin composition of the present invention.

[0067] [[Method for Manufacturing Resin Molded Articles]] The resin molded articles of the present invention can be manufactured by molding the crosslinked resin composition of the present invention into a predetermined shape and dimensions. The crosslinked resin composition of the present invention maintains its moldability even as a crosslinked product and has the characteristic of being able to be molded even after crosslinking. When the crosslinkable resin composition of the present invention or the crosslinked resin composition is melt-kneaded in an extruder or the like, a resin molded article can be obtained simultaneously with or after the manufacture of the crosslinkable resin composition or the crosslinked resin composition of the present invention. The molding method is not particularly limited and includes, for example, press molding, extrusion molding using an extruder, extrusion molding using an injection molding machine, and molding using other molding machines. The molding temperature should be above the temperature at which the crosslinked resin composition melts, for example, it can be 100 to 240°C, and preferably 140 to 240°C.

[0068] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0069] Details of each compound used in the examples and comparative examples are shown in Table 1 and below. <Base resin> PE: Polyethylene (UBEC180 (trade name), manufactured by Ube Maruzen Polyethylene Co., Ltd.) EVA saponified: Saponified ethylene vinyl acetate copolymer (Mersen® H-6051K (trade name), manufactured by Tosoh Corporation) <Organic peroxide> 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (Perhexa 25B (trade name), manufactured by NOF Corporation) <Silane coupling agent> VTMS: Vinyltrimethoxysilane (KBM-1003 (trade name), manufactured by Shin-Etsu Chemical Co., Ltd.) VTES: Vinyltriethoxysilane (KBE-1003 (trade name), manufactured by Shin-Etsu Chemical Co., Ltd.) <Boron compound> Boric acid: Orthoboric acid (manufactured by Ken-ei Pharmaceutical Co., Ltd.) Boronic acid: 1,4-Phenylenediboronic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) <Silanol condensation catalyst> OT-1: Dioctyl tin dilaurate (ADEKA stab OT-1 (product name), manufactured by ADEKA Corporation)

[0070] [Example A and Comparative Example C: Progress Test of Crosslinking Reaction] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded in a laboplastmill at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes (silane graft polymer was prepared). Then, 1.8 g of boric acid (Example A) or 0.2 g of dioctyl tin dilaurate (Comparative Example C) was added to the mixture, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition A of Example A and crosslinkable resin composition C of Comparative Example C were prepared. The boron atom content in crosslinkable resin composition A was 0.171 parts by mass per 100 parts by mass of the base resin (silane graft polymer). Immediately after preparation (within one hour of melt-kneading completion), each composition was rolled to a thickness of 1 mm, and then pressed at 140°C for 10 minutes (press pressure 15.8 MPa) to produce sheet samples A1 and C1, and the gel fraction was measured. In addition, the gel fraction of sheet samples A2 and C2 was measured after each sheet sample was left to stand for 7 days under moist heat conditions of 60°C and 95% relative humidity in an air atmosphere. The gel fraction is a parameter indicating the degree of crosslinking and was measured by the xylene method specified in JIS C 3005.

[0071] As a result, sheet samples prepared using crosslinkable resin composition A containing boric acid showed a gel fraction of 70% (saturation value) both immediately after mixing (A1) and after standing for 7 days (A2). Furthermore, when sheet sample A3, which was prepared by standing sheet sample A1 for 7 days under atmospheric conditions of 25°C and 50% relative humidity, was measured for gel fraction, it was also 70% (saturation value). On the other hand, sheet samples prepared using crosslinkable resin composition C containing dioctyltin dilaurate showed a gel fraction of 48% immediately after mixing (sheet sample C1) and a gel fraction of 70% (saturation value) after standing for 7 days (sheet sample C2). From these results, it was confirmed that when using dioctyltin dilaurate with a base resin containing a polymer having at least one hydroxyl group and a hydroxyl group precursor, the crosslinking reaction takes time to complete, whereas when using boric acid, the crosslinking reaction is completed rapidly. Furthermore, the fact that the kneading torque of the Laboplastmill increased immediately after the addition of boric acid during the melt mixing of crosslinkable resin composition A also supported the fact that the crosslinking reaction was proceeding rapidly. When the progress of the crosslinking reaction was tested in the same manner as in Example A, except that boronic acid was used instead of boric acid, the same results as in Example A were obtained.

[0072] [Examples 1-9 and Comparative Examples 1-3] In Examples 1-9 and Comparative Examples 1-3, each composition prepared as described below was rolled to a thickness of 1 mm, then pressed at 140°C for 10 minutes (press pressure 15.8 MPa) to produce sheet samples, which were then left to stand for 7 days in air at a temperature of 25°C and a relative humidity of 50%. In Examples 1-9, it was confirmed that the kneading torque of the Laboplast Mill had increased sufficiently (indicating that the crosslinking reaction had progressed) 10 minutes after adding the boron-based compound to the base resin (crosslinkable polymer) during melt kneading (10 minutes of kneading time after addition).

[0073] Sheet samples left standing in the atmosphere for 7 days were subjected to gel fraction measurement and tensile testing. The gel fraction was measured by the xylene method specified in JIS C 3005, and in this example and comparative example, it is desirable to have a gel fraction of 50% or more. The tensile test was performed according to JIS K 7161, under conditions of a gauge length of 20 mm and a tensile speed of 200 mm / min, and the 100% Modulus (MPa) and tensile elongation (%) were measured. This test is a reference test, and in this test, it is desirable for the 100% Modulus to be 11.0 MPa or more and for the tensile elongation to be 150% or more. In each example and comparative example, the boron atom content in the prepared resin composition was calculated from the blending amount at the time of preparation of the crosslinkable resin composition, and the value is shown in Table 1 as the content per 100 parts by mass of base resin (100 parts by mass of the crosslinkable polymer and silane coupling agent combined).

[0074] [Example 1] To 180 g of polyethylene (PE) being kneaded at 150°C, a mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added and kneaded at 60 rpm for 30 minutes. Then, 0.2 g of boric acid was added and kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 1 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 1.

[0075] [Example 2] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 0.9 g of boric acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 2 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 2.

[0076] [Example 3] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 1.8 g of boric acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 3 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 3.

[0077] [Example 4] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 5.2 g of boric acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 4 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 4.

[0078] [Example 5] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 18.0 g of boric acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 5 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 5.

[0079] [Example 6] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 30.0 g of boric acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 6 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 6.

[0080] [Example 7] A mixture of 5.1 g of VTES and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 1.8 g of boric acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 7 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 7.

[0081] [Example 8] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 1.8 g of boronic acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 8 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 8.

[0082] [Example 9] A mixture of 3.5 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 160 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 20.0 g of saponified ethylene vinyl acetate copolymer (EVA saponified) was added and the mixture was kneaded at 60 rpm for 5 minutes, and then 1.8 g of boric acid was added and the mixture was kneaded at 60 rpm for 10 minutes. In this way, crosslinkable resin composition 9 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this crosslinkable resin composition 9.

[0083] [Comparative Example 1] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. In this way, resin composition C1 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this resin composition C1.

[0084] [Comparative Example 2] A mixture of 4.0 g of VTMS and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 0.1 g of boric acid was added, and the mixture was kneaded at 60 rpm for 10 minutes. In this way, resin composition C2 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this resin composition C2.

[0085] [Comparative Example 3] A mixture of 5.1 g of VTES and 0.2 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to 180 g of polyethylene being kneaded at 150°C, and the mixture was kneaded at 60 rpm for 30 minutes. Then, 0.2 g of dioctyl tin dilaurate (OT-1) was added as a silanol condensation catalyst (simply referred to as "condensation catalyst" in Table 1), and the mixture was kneaded at 60 rpm for 10 minutes. In this way, resin composition C3 was prepared. Table 1 shows the results of measuring the gel fraction, 100% Modulus, and tensile elongation of a sheet sample prepared using this resin composition C3.

[0086] [Example 10] A crosslinkable resin composition 10 was prepared by mixing an aqueous solution of polyvinyl alcohol with boric acid instead of polyethylene. It was confirmed that the crosslinking reaction proceeded rapidly even in a crosslinkable resin composition 10 containing polyvinyl alcohol alone as the base resin.

[0087]

[0088] The results shown in Table 1 indicate the following: In resin composition C1 (Comparative Example 1), which does not contain boron compounds or dioctyl tin dilaurate, the crosslinking reaction of the crosslinkable polymer did not proceed even after 7 days. On the other hand, in resin composition C2 (Comparative Example 2), which has too little boron content, the crosslinking reaction of the crosslinkable polymer occurred, but it did not proceed smoothly. This suggests that the boron compounds are not acting as catalysts to promote the crosslinking reaction, like dioctyl tin dilaurate, but rather may be incorporated into the crosslinking structure.

[0089] In contrast, in the crosslinkable resin compositions 1 to 9 of Examples 1 to 9, which contain a boron compound in a predetermined proportion to form boron atoms, the torque increased 10 minutes after the addition of the boron compound, confirming that the crosslinking reaction of the crosslinkable polymer proceeded rapidly. Furthermore, it was confirmed that the 100% Modulus and tensile elongation of the sheet samples prepared with crosslinkable resin compositions 1 to 9 exhibited sufficient performance. In addition, although crosslinkable resin composition 7 of Example 7 contains VTES, which is less reactive than VTMS, the crosslinking reaction proceeded rapidly due to the boron compound. This is clear from the torque increase mentioned above and the comparison results of gel fraction with Comparative Example 3. Therefore, in the present invention, when using a silane graft polymer, a silane coupling agent with lower crosslinking reactivity than VTMS can be used, and the constraints regarding the silane coupling agent can be relaxed or eliminated. In particular, highly crosslinkable silane coupling agents are highly volatile and pose a risk of deteriorating the working environment. However, there is an advantage in being able to use silane coupling agents that can improve the working environment and enhance safety as an alternative to highly crosslinkable silane coupling agents.

[0090] From the above results, it can be seen that the present invention can rapidly complete the crosslinking reaction without requiring special crosslinking equipment such as an electron beam generator, and without using organotin compounds as silanol condensation catalysts, which are of concern due to their impact on the environment and human health. Since the crosslinking reaction proceeds rapidly from the preparation of the crosslinkable resin composition, the crosslinking reaction can be rapidly carried out and completed even if the object to be crosslinked is thick or large in size, thus alleviating or eliminating the limitations on the object to be crosslinked that were a problem in the past. Moreover, since the crosslinking reaction proceeds rapidly from the preparation of the crosslinkable resin composition, it is possible to alleviate or eliminate the limitations on the polymer used (regarding the glass transition temperature), as in the organic peroxide crosslinking method, and it can be seen that a wide variety of polymers can be used.

[0091] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0092] This application claims priority based on Japanese Patent Application No. 2024-199863, filed in Japan on November 15, 2024, the contents of which are incorporated herein by reference as part of this specification.

Claims

1. A crosslinkable resin composition comprising a base resin containing a polymer having at least one of a hydroxyl group and a hydroxyl group precursor, and a boron compound, wherein the content of boron atoms per 100 parts by mass of the base resin is 0.019 parts by mass or more.

2. The crosslinkable resin composition according to claim 1, wherein the boron compound has a B-O bond.

3. The crosslinkable resin composition according to claim 1, wherein the boron compound is any of boric acid, boronic acid, and borate.

4. The crosslinkable resin composition according to claim 1, wherein the polymer comprises a structure derived from a silane coupling agent.

5. The crosslinkable resin composition according to claim 4, wherein the silane coupling agent has an alkoxysilyl group.

6. A crosslinked resin composition obtained by crosslinking the crosslinkable resin composition according to any one of claims 1 to 5.

7. The crosslinked resin composition according to claim 6, having a B-O bond.

8. A resin molded article comprising the crosslinked resin composition described in claim 6.

9. A resin composition kit comprising a first agent containing a polymer having at least one hydroxyl group and a hydroxyl group precursor, and a second agent containing a boron compound.

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