Polyolefin composition, silane crosslinkable molded body, silane crosslinked molded body and use of same

Abstract

The present invention relates to a polyolefin composition which contains a polyolefin and a zinc compound that is represented by formula (1)' Zn(OCOR1)(OCOR2). In formula (1)', each of R1 and R2 independently represents a branched saturated hydrocarbon group having 9 to 11 carbon atoms.

Description

Polyolefin composition, silane-crosslinkable molded article, and silane-crosslinked molded article and use thereof

[0001] The present invention relates to a polyolefin composition, a silane-crosslinkable molded article, and a silane-crosslinked molded article and use thereof.

[0002] Silane-crosslinked polyolefins obtained using silanol condensation catalysts are widely used in applications such as coating materials for electric wires and cables, pipes, hoses, and tubes.

[0003] The silane-crosslinked polyolefin is obtained by graft polymerizing an organosilane compound onto a polyolefin in the presence of a radical generator, followed by the addition of water in the presence of a silanol condensation catalyst. This reaction with water in the presence of a silanol condensation catalyst is called "silane-water crosslinking."

[0004] In silane water crosslinking, a radical generator is typically applied to a polyolefin as a graft initiator in a molding machine such as an extruder. This allows an organosilane compound such as an alkoxysilane to be graft-copolymerized onto the polyolefin. The crosslinking reaction can then be initiated by applying water to the molded product produced by the molding machine. The crosslinking reaction occurs through the hydrolysis and condensation reaction of the organosilane compound caused by the action of a silanol condensation catalyst. The silanol condensation catalyst can be premixed into the molded product or can be infiltrated into the molded product from its surface.

[0005] As a silanol condensation catalyst used in silane-crosslinked polyolefins, Patent Document 1 discloses a silanol condensation catalyst-containing composition containing a specific silanol condensation catalyst and polyethylene, which is an alternative to the organotin compounds that have been widely used in the past and poses less environmental load.

[0006] Japanese Patent Application Publication No. 2018-090734

[0007] The silanol condensation catalyst-containing composition described in Patent Document 1 has low environmental impact and exhibits good catalytic performance for crosslinking reactions. However, the inventors' investigations have revealed that the silanol condensation catalyst-containing composition has a yellowish tint, and therefore there is room for improvement in terms of yellowness.

[0008] Therefore, an object of the present invention is to provide a polyolefin composition containing a zinc compound, which has low environmental impact, good crosslinking performance, and reduced yellowness. Another object of the present invention is to provide a silane-crosslinkable molded article containing the polyolefin composition, a silane-crosslinked molded article obtained by crosslinking such a molded article, and uses thereof.

[0009] In addition to the above-mentioned objectives, another objective of the present invention is to achieve effects that are derived from the various components shown in the description of the embodiments of the invention described below, and that cannot be obtained by conventional techniques.

[0010] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using a specific zinc compound, and have thus completed the present invention. That is, one aspect of the present invention is as follows.

[0011] [1] A polyolefin composition containing a zinc compound represented by the following formula (1)' and a polyolefin: Zn(OCOR １ ) (OCOR ２ ) ... (1)' (In formula (1)', R １ and R ２are each independently a branched saturated hydrocarbon group having 9 to 11 carbon atoms.) [2] The polyolefin composition according to the above item [1], having a tin content of less than 100 ppm by mass. [3] The polyolefin composition according to the above item [1] or [2], having a zinc content of 0.10% by mass or more. [4] The polyolefin composition according to the above item [3], having a zinc content of 3.0% by mass or less. [5] The polyolefin composition according to any one of the above items [1] to [4], comprising as the polyolefin at least one selected from the group consisting of polyethylene and polypropylene. [6] The polyolefin composition according to any one of the above items [1] to [5], which is a catalyst masterbatch. [7] The polyolefin composition according to any one of the above items [1] to [6], further comprising a silane-modified polyolefin.

[0012] [8] A silane-crosslinkable molded article comprising a silane-modified polyolefin and a zinc compound represented by the following formula (1)': Zn(OCOR １ ) (OCOR ２ ) ... (1)' (In formula (1)', R １ and R ２ are each independently a branched saturated hydrocarbon group having 9 to 11 carbon atoms.) [9] A silane-crosslinked molded article obtained by crosslinking the silane-crosslinkable molded article according to [8] above.

[10] The silane-crosslinked molded article according to [9] above, which is a wire coating material, a cable coating material, a pipe, a hose, a tube, a container, a sealing material, a film, or a sheet.

[11] The silane-crosslinked molded article according to [9] above, which is a coolant tube.

[12] The silane-crosslinked molded article according to [9] above, which is a coolant tube member.

[13] The silane-crosslinked molded article according to [9] above, which is a lithium-ion battery separator.

[14] The silane-crosslinked molded article according to [9] above, which is a lithium-ion battery separator member.

[0013]

[15] Use of the silane-crosslinked molded article according to the above [9] as a coolant tube.

[16] Use of the silane-crosslinked molded article according to the above [9] as a coolant tube member.

[17] Use of the silane-crosslinked molded article according to the above [9] as a lithium-ion battery separator.

[18] Use of the silane-crosslinked molded article according to the above [9] as a lithium-ion battery separator member.

[0014] According to the present invention, a polyolefin composition containing a zinc compound can be provided, which has low environmental impact, good crosslinking performance, and reduced yellowness. Therefore, the silane-crosslinked molded article obtained using the polyolefin composition also has excellent colorability and is very useful as a product such as a wire coating material.

[0015] The following describes in detail the embodiments of the present invention, but the following embodiments are merely examples (typical examples) of the present invention and the present invention is not limited thereto. The present invention can be implemented by any modifications within the scope of the gist thereof. In this specification, when a numerical value or physical property value is enclosed before and after "~", the values ​​before and after the "~" are used to include the values ​​before and after the "~". In addition, in this specification, "mass %" and "wt %", "parts by mass" and "parts by weight", and "ppm by mass" and "ppm by weight" are synonymous.

[0016] <Polyolefin Composition> The polyolefin composition according to this embodiment contains a zinc compound represented by the following formula (1) and a polyolefin: Zn(OCOR １ ) (OCOR ２ ) ... (1) (In formula (1), R １ and R ２ are each independently a saturated hydrocarbon group.

[0017] In the polyolefin composition according to this embodiment, the zinc compound represented by the formula (1) preferably functions as a silanol condensation catalyst. The zinc compound represented by the formula (1) is a compound with low environmental impact, has good catalytic performance, and exhibits excellent crosslinking performance. Furthermore, the resulting polyolefin composition has reduced yellowness. Therefore, by using the polyolefin composition, a molded article made of a silane-modified polyolefin with excellent crosslinking performance or a crosslinked silane-crosslinked molded article can be obtained, while also reducing yellowness.

[0018] The zinc compound represented by formula (1) in this embodiment is R １ and R ２ are each independently a branched saturated hydrocarbon group having 9 to 11 carbon atoms. That is, the polyolefin composition according to this embodiment preferably contains a zinc compound represented by the following formula (1)' and a polyolefin. Zn(OCOR １ ) (OCOR ２ ) ... (1)' (In formula (1)', R １ and R ２ are each independently a branched saturated hydrocarbon group having 9 to 11 carbon atoms.

[0019] Furthermore, while the silanol condensation catalyst-containing composition described in Patent Document 1 was found to have a distinctive odor, the polyolefin composition according to the present embodiment was found to be able to reduce odor in addition to reducing yellowness. Therefore, by using the polyolefin composition, it is possible to reduce odor even in molded articles made of silane-modified polyolefins and silane-crosslinked molded articles.

[0020] The reason why the polyolefin composition according to this embodiment exhibits the above-mentioned effects is unclear, but is presumed to be as follows. The silanol condensation catalyst specifically disclosed in Patent Document 1 contains a predetermined amount of alkylamine as an active ingredient. In comparison, however, the zinc compound represented by formula (1), particularly the zinc compound represented by formula (1)', exhibits reduced yellowness and odor. Therefore, it is believed that by incorporating a zinc compound represented by formula (1) or formula (1)' as a silanol condensation catalyst, the yellowness and odor of the polyolefin composition, as well as of a molded article or silane-crosslinked molded article made of silane-modified polyolefin, are reduced.

[0021] In addition to the above, the presence of the zinc compound represented by formula (1) or formula (1)' above makes it possible to achieve crosslinking performance equivalent to that of the silanol condensation catalyst-containing composition specifically disclosed in Patent Document 1. This is thought to be due to the fact that, in the presence of water, the functional group bonded to or coordinated to the zinc element in the zinc compound represented by formula (1) or formula (1)' quickly converts to an OH group. This rapid conversion of the functional group is thought to result in high catalytic activity for the silanol condensation reaction with silane-modified polyolefins.

[0022] For the above reasons, it is believed that the polyolefin composition containing the zinc compound of the present embodiment exhibits excellent crosslinking performance equivalent to that of the silanol condensation catalyst-containing composition disclosed in Patent Document 1, while exhibiting reduced yellowness and odor.

[0023] <Zinc Compound> The zinc compound in this embodiment acts as a catalyst component in the silanol condensation reaction when obtaining a silane-crosslinked polyolefin. The zinc compound is a zinc compound represented by the following formula (1), and is preferably a zinc compound represented by formula (1)'. Zn(OCOR １ ) (OCOR ２ ) ... (1) (In formula (1), R １ and R ２ are each independently a saturated hydrocarbon group. １ ) (OCOR ２ ) ... (1)' (In formula (1)', R １ and R２ are each independently a branched saturated hydrocarbon group having 9 to 11 carbon atoms.

[0024] In the zinc compound represented by the above formula (1), R １ and R ２ are each independently a saturated hydrocarbon group. The saturated hydrocarbon group preferably has 5 to 15 carbon atoms, more preferably 7 to 13, and even more preferably 9 to 11. From the viewpoint of controlling the silanol condensation reaction, the saturated hydrocarbon group preferably has 5 or more carbon atoms, more preferably 7 or more, and even more preferably 9 or more carbon atoms, and preferably has 15 or less, more preferably 13 or less, and even more preferably 11 or less carbon atoms.

[0025] The saturated hydrocarbon group may be linear, branched, or cyclic. From the viewpoint of controlling the silanol condensation reaction, R １ and R ２ Preferably, at least one of R １ and R ２ It is more preferable that both R １ and R ２ It is more preferable that at least one of R is a branched saturated hydrocarbon group having 5 to 15 carbon atoms, １ and R ２ are more preferably branched saturated hydrocarbon groups having 5 to 15 carbon atoms, and even more preferably branched saturated hydrocarbon groups having 9 to 11 carbon atoms. １ and R ２ It is also preferable that the

[0026] In the polyolefin composition according to this embodiment, the content of the zinc compound represented by formula (1) or (1)' is preferably 0.3% by mass or more, and more preferably 0.3 to 15% by mass. From the viewpoint of exhibiting the function as a silanol condensation catalyst, the content is preferably 0.3% by mass or more, more preferably 0.4% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 0.8% by mass or more. From the viewpoint of reducing the yellowness and odor of the resulting polyolefin composition, the content is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. When two or more zinc compounds represented by formula (1) or formula (1)' are contained, the total content thereof is preferably within the above range.

[0027] The zinc content in the polyolefin composition according to this embodiment is preferably 0.10% by mass or more, and preferably 0.10 to 3.0% by mass. From the viewpoint of exhibiting the function as a silanol condensation catalyst, the content is preferably 0.10% by mass or more, more preferably 0.11% by mass or more, and even more preferably 0.12% by mass or more. Furthermore, from the viewpoint of reducing the yellowness and odor of the resulting polyolefin composition, the content is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less.

[0028] In the silanol condensation catalyst of this embodiment, the content of the zinc compound represented by formula (1) or formula (1)' is preferably 10 to 100% by mass. From the viewpoint of exerting the effects of the zinc compound represented by formula (1) or formula (1)', the content is preferably 10% by mass or more, more preferably 40% by mass or more, even more preferably 70% by mass or more, and even more preferably 85% by mass or more. Furthermore, from the viewpoint of reducing the odor of the resulting polyolefin composition, the content is particularly preferably 90% by mass or more. The upper limit of the content is not particularly limited, and may be 100% by mass, i.e., the silanol condensation catalyst may consist solely of the zinc compound represented by formula (1) or formula (1)'. When two or more zinc compounds represented by formula (1) or formula (1)' are contained, the total content thereof is preferably within the above range.

[0029] The silanol condensation catalyst of this embodiment may contain components other than the zinc compound represented by formula (1) or formula (1)'. Examples of other components include other metal compounds and organic solvents, and conventionally known compounds can be used for these.

[0030] Due to the presence of the zinc compound represented by formula (1) or formula (1)', the polyolefin composition according to this embodiment has low environmental impact, good crosslinking performance, and reduced yellowness. Therefore, for example, the polyolefin composition may be substantially free of tin, which is conventionally known as a catalyst. Specifically, the tin content in the polyolefin composition according to this embodiment may be less than 100 ppm by mass.

[0031] The zinc compound represented by formula (1) or formula (1)' in this embodiment may be manufactured or may be commercially available. As a commercially available compound, for example, a compound satisfying formula (1) or formula (1)' from the K-KAT (registered trademark) series manufactured by King Industries can be used.

[0032] <<Polyolefin>> The polyolefin composition according to this embodiment contains a polyolefin. The polyolefin in this embodiment is not particularly limited, and a conventionally known polyolefin can be used. However, the polyolefin does not include the silane-modified polyolefin described below, and is used to distinguish it from this.

[0033] Examples of polyolefins in the present embodiment include polyethylene and polypropylene, and it is preferable to include at least one selected from the group consisting of polyethylene and polypropylene.

[0034] Polyethylene Any polyethylene can be used, including ethylene homopolymers such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), and ethylene-α-olefin copolymers such as ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-pentene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, and ethylene-propylene-1-hexene copolymers. Of these, ethylene homopolymers are preferred, and low-density polyethylene (LDPE) is more preferred. Furthermore, one type of polyethylene may be used, or two or more types may be used in combination.

[0035] The melt flow rate (MFR) of the polyethylene in this embodiment is not particularly limited, but is typically 0.1 to 80 g / 10 min. The MFR of the polyethylene is typically 0.1 g / 10 min or more, but from the viewpoints of moldability of the crosslinked silane-modified polyolefin and uniform dispersion during melt-kneading with the silane-modified polyolefin, it is preferably 0.5 g / 10 min or more, and more preferably 1 g / 10 min or more. The MFR of the polyethylene is typically 80 g / 10 min or less, but from the same viewpoints as above, it is preferably 60 g / 10 min or less, more preferably 40 g / 10 min or less, even more preferably 20 g / 10 min or less, and particularly preferably 15 g / 10 min or less. In this specification, the MFR of polyethylene is a value measured at a temperature of 190°C and a load of 21.2 N in accordance with JIS K 7210:1999.

[0036] The density of the polyethylene in this embodiment is usually 0.850 to 0.970 g / cm ３ and 0.855 to 0.965 g / cm ３ In this specification, the density of polyethylene is a value measured in accordance with JIS K 7112:1999.

[0037] Polypropylene In this embodiment, the polypropylene may be a propylene homopolymer or a propylene-ethylene copolymer. As the propylene-ethylene copolymer, for example, any of propylene-α-olefin copolymers such as a propylene-1-butene copolymer or a propylene-ethylene-1-butene copolymer can be used. Furthermore, one type of polypropylene may be used, or two or more types may be used in combination.

[0038] The melt flow rate (MFR) of the polypropylene in this embodiment is not particularly limited, but is typically 0.1 to 120 g / 10 min. The MFR of the polypropylene is typically 0.1 g / 10 min or higher, but from the viewpoints of moldability of the crosslinked silane-modified polyolefin and uniform dispersion during melt-kneading with the silane-modified polypropylene, it is preferably 0.3 g / 10 min or higher, and more preferably 0.5 g / 10 min or higher. Furthermore, the MFR of the polypropylene is typically 120 g / 10 min or lower, but from the same viewpoints as above, it is preferably 100 g / 10 min or lower, more preferably 80 g / 10 min or lower, even more preferably 60 g / 10 min or lower, and particularly preferably 40 g / 10 min or lower. In this specification, the MFR of polypropylene is a value measured at a temperature of 230°C and a load of 21.2 N in accordance with JIS K 7210:1999.

[0039] The density of the polypropylene in this embodiment is usually 0.850 to 0.930 g / cm ３ and 0.855 to 0.920 g / cm ３ In this specification, the density of polypropylene is a value measured in accordance with JIS K 7112:1999.

[0040] In the present embodiment, when the polyolefin is, for example, polyethylene or polypropylene, it is preferable to use one that satisfies at least one of the MFR and density described above, and it is more preferable to use one that satisfies both the MFR and density. This allows the polyolefin composition according to the present embodiment to be easily handled and produced, and also allows the polyolefin composition to be more uniformly mixed and dispersed in the silane-modified polyolefin.

[0041] The polyolefin in this embodiment may be manufactured or commercially available, such as the Novatec (registered trademark) series, Newcon (registered trademark) series, Wintec (registered trademark) series, Wellnex (registered trademark) series, and Waymax (registered trademark) series manufactured by Japan Polypropylene Corporation, and the Zelas (registered trademark) series manufactured by Mitsubishi Chemical Corporation.

[0042] <Silane-Modified Polyolefin> The polyolefin composition according to this embodiment may further contain a silane-modified polyolefin.

[0043] The silane-modified polyolefin in this embodiment is not particularly limited as long as it is obtained by reacting a polyolefin with an unsaturated silane compound. The polyolefin to be reacted with the unsaturated silane compound can be, for example, the polyolefins exemplified in the above-mentioned section "Polyolefin."

[0044] The unsaturated silane compound is not particularly limited, but is preferably a compound represented by the following formula (2): The unsaturated silane compound may be used alone or in combination of two or more kinds. ３ Si(R ４ ) ３ ... (2) (In the above formula (2), R ３ is an olefinically unsaturated hydrocarbon group, and R ４ are each independently a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and R ４ At least one of the groups is an alkoxy group having 1 to 10 carbon atoms.

[0045] In the above formula (2), R ３ is an olefinically unsaturated hydrocarbon group, preferably an olefinically unsaturated hydrocarbon group having 2 to 10 carbon atoms, more preferably an olefinically unsaturated hydrocarbon group having 2 to 6 carbon atoms. ３ More specifically, examples of the alkyl group include alkenyl groups such as vinyl, propenyl, butenyl, and cyclohexenyl.

[0046] In the above formula (2), R４ are each independently a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, preferably a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and more preferably a hydrocarbon group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. ４ At least one of the groups is an alkoxy group having 1 to 10 carbon atoms, preferably an alkoxy group having 1 to 6 carbon atoms, and more preferably an alkoxy group having 1 to 4 carbon atoms.

[0047] R ４ When R is a hydrocarbon group having 1 to 10 carbon atoms, the hydrocarbon group may be any of an alkyl group, an aliphatic group, an alicyclic group, and an aromatic group, but is preferably an alkyl group. ４ Specific examples of the alkyl group include alkyl groups such as methyl, ethyl, isopropyl, t-butyl, n-butyl, i-butyl, and cyclohexyl groups, and aryl groups such as phenyl groups.

[0048] R ４ When R is an alkoxy group having 1 to 10 carbon atoms, the alkoxy group may be linear, branched, or cyclic, but is preferably linear or branched. ４ Specific examples of the alkyl group include a methoxy group, an ethoxy group, an isopropoxy group, and a β-methoxyethoxy group.

[0049] When the unsaturated silane compound is represented by the above formula (2), three R ４ At least one of R is an alkoxy group having 1 to 10 carbon atoms, but two or more R ４ is preferably an alkoxy group, and all R ４ is more preferably an alkoxy group.

[0050] Among the unsaturated silane compounds represented by the above formula (2), vinyltrialkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and propenyltrimethoxysilane are more preferred because the vinyl group allows modification to polyolefins, and the alkoxy group promotes the following crosslinking reaction.

[0051] The crosslinking reaction is a process in which the alkoxy groups introduced by graft modification onto the modified polyolefin with the unsaturated silane compound react with water in the presence of a silanol condensation catalyst to hydrolyze and generate silanol groups, and the resulting silanol groups then undergo dehydration condensation, bonding the modified polyolefins together and causing a crosslinking reaction.

[0052] In this embodiment, the modification amount of the unsaturated silane compound in the silane-modified polyolefin, i.e., the amount of unsaturated silane compound introduced into the silane-modified polyolefin by graft modification, is preferably 0.1 to 5% by mass. From the viewpoint of heat resistance, the modification amount is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more. From the viewpoint of moldability, the modification amount is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and even more preferably 3.0% by mass or less. The modification amount of the unsaturated silane compound is the mass ratio of the unsaturated silane compound introduced by graft modification to the polyolefin before modification.

[0053] The silane-modified polyolefin in this embodiment may be graft-modified by using a compound other than the unsaturated silane compound in combination, provided that the effects of the present invention are not impaired. Examples of the compound other than the unsaturated silane compound include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, and isocrotonic acid, and acid anhydrides thereof.

[0054] The silane-modified polyolefin of this embodiment can be produced by graft-modifying a polyolefin with the unsaturated silane compound. There are no particular limitations on the graft-modification method, and conventionally known methods can be used. For example, solution modification, melt modification, solid-phase modification by irradiation with an electron beam or ionizing radiation, modification in a supercritical fluid, etc. are preferably used. Among these, melt modification is preferred because of its superior equipment and cost competitiveness, and melt-kneading modification using an extruder with excellent continuous productivity is more preferred.

[0055] Examples of devices used for melt-kneading modification include single-screw extruders, twin-screw extruders, Banbury mixers, roll mixers, etc. Among these, single-screw extruders and twin-screw extruders are preferred because of their excellent continuous productivity.

[0056] Generally, the graft modification of polyolefin with an unsaturated silane compound is carried out by a graft reaction in which the carbon-hydrogen bond of the polyolefin is cleaved to generate a carbon radical to which an unsaturated functional group is added.

[0057] As a source of carbon radical generation, in addition to the above-mentioned electron beams and ionizing radiation, a method using high temperature or a method using a radical generator such as an organic or inorganic peroxide can also be used. From the viewpoint of cost and operability, it is preferable to use an organic peroxide. One type of radical generator may be used alone, or two or more types may be used in combination.

[0058] The radical generator used in producing the silane-modified polyolefin is not limited, but examples of organic peroxides include hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, and ketone peroxides. Other examples of the radical generator include azo compounds.

[0059] Of the above radical generators, the hydroperoxide group includes cumene hydroperoxide, tert-butyl hydroperoxide, etc. The dialkyl peroxide group includes dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhexyne-3, etc. The diacyl peroxide group includes lauryl peroxide, benzoyl peroxide, etc. The peroxy ester group includes tert-peroxyacetate, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, etc. The ketone peroxide group includes cyclohexanone peroxide, etc. Azo compounds include azobisisobutyronitrile, methyl azoisobutyrate, etc.

[0060] A commonly used melt extrusion modification procedure involves compounding and blending a polyolefin, an unsaturated silane compound, and an organic peroxide, feeding the blend into a kneader or extruder, extruding the mixture while heating, melting, and kneading it, and cooling the molten resin emerging from the tip of a die in a water tank or the like to obtain a silane-modified polyolefin.

[0061] The blending ratio of the polyolefin and the unsaturated silane compound is not particularly limited, but for example, the blending ratio of the unsaturated silane compound is preferably 0.5 to 10 parts by mass per 100 parts by mass of the polyolefin. Here, from the viewpoint of obtaining the predetermined modification amount necessary to achieve the intended effect, the blending ratio is preferably 0.5 parts by mass or more. Furthermore, from the viewpoint of preventing a large amount of unreacted unsaturated silane compound from remaining and adversely affecting performance, the blending ratio is preferably 10 parts by mass or less.

[0062] The blending ratio of the unsaturated silane compound to the organic peroxide is not particularly limited, but for example, the blending ratio of the organic peroxide is preferably 0.1 to 100 parts by mass per 100 parts by mass of the unsaturated silane compound. Here, from the viewpoint of generating a sufficient amount of radicals and easily achieving the required predetermined modification amount, the blending ratio is preferably 0.1 parts by mass or more. Furthermore, from the viewpoint of suppressing degradation of the polyolefin, the blending ratio is preferably 100 parts by mass or less.

[0063] As for the conditions for the melt extrusion modification, it is preferable to extrude at a temperature of about 150 to 300°C in a single screw extruder or a twin screw extruder.

[0064] The silane-modified polyolefin used in this embodiment may be a manufactured product or a commercially available product, such as a product from the Linklon series manufactured by Mitsubishi Chemical Corporation.

[0065] In addition, when the polyolefin composition according to the present embodiment further comprises a silane-modified polyolefin, one embodiment of the polyolefin composition according to the present embodiment includes a composition obtained by melt-kneading a polyolefin, a zinc compound represented by formula (1) or formula (1)', and the silane-modified polyolefin. Another embodiment includes a composition obtained by melt-kneading a polyolefin, an unsaturated silane compound, and a radical generator, which are raw materials for the silane-modified polyolefin, to simultaneously produce the silane-modified polyolefin by graft modification and melt-kneading the polyolefin and the zinc compound represented by formula (1) or formula (1)'. In this other embodiment, instead of melt-kneading the polyolefin and the zinc compound represented by formula (1) or formula (1)', melt-kneading with a silanol condensation catalyst masterbatch containing the polyolefin and the zinc compound represented by formula (1) or formula (1)' may be performed. Thus, even when the polyolefin composition according to the present embodiment comprises a silane-modified polyolefin, the order of melt-kneading and other aspects are not limited in any way.

[0066] Other Components In addition to the components described above, the polyolefin composition according to the present embodiment may contain optional components such as other additives and resins other than polyolefins depending on various purposes, as long as the effects of the present invention are not significantly impaired.

[0067] Examples of other additives include antioxidants, lubricants, colorants, heat stabilizers, light stabilizers, ultraviolet absorbers, neutralizing agents, antifogging agents, antiblocking agents, slip agents, flame retardants, dispersants, antistatic agents, conductivity imparting agents, metal deactivators, molecular weight modifiers, antibacterial agents, fluorescent brighteners, crystal nucleating agents, etc. These may be used alone or in combination of two or more, depending on the purpose.

[0068] Examples of the antioxidant include phenol-based antioxidants, phosphite-based antioxidants, thioether-based antioxidants, etc. When an antioxidant is used, it is generally used in an amount of 0.1 to 30 parts by mass per 100 parts by mass of the total of the polyolefins in this embodiment.

[0069] Examples of lubricants include oleic acid amide, erucic acid amide, silicone oil, fluorine-based resins, etc. When a lubricant is used, it is generally used in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the total of the polyolefins in this embodiment.

[0070] Examples of other resins include styrene-based thermoplastic elastomers, polyester resins, polyamide resins, styrene resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, and various elastomers (excluding those corresponding to the polyolefins in this embodiment). The other resins listed above may be used alone or in combination of two or more. The other resins are typically used in an amount of 50 parts by mass or less per 100 parts by mass of the total of the polyolefins in this embodiment.

[0071] <<Method for Producing Polyolefin Composition>> The polyolefin composition according to this embodiment can be produced by kneading the zinc compound represented by formula (1) or formula (1)′ and the polyolefin, together with the silane-modified polyolefin and other components as needed, in a twin-screw kneader or the like at a temperature of 120 to 230° C. Furthermore, the resulting mixture may be pelletized as needed.

[0072] Form and Properties of Polyolefin Composition Masterbatch The polyolefin composition according to this embodiment is preferably, for example, in the form of a masterbatch, more preferably a catalyst masterbatch, and even more preferably a silanol condensation catalyst masterbatch. Here, "masterbatch" refers to a state in which a polyolefin composition containing a high concentration of an active ingredient such as a silanol condensation catalyst is granulated, or a resin mass is crushed to form pellets.

[0073] The catalyst masterbatch in this embodiment is made of the polyolefin composition according to this embodiment. By using the polyolefin composition according to this embodiment as a catalyst masterbatch for producing a crosslinked product, it is possible to provide a silane-crosslinked molded product having a good color, i.e., reduced yellowness, and preferably also reduced odor.

[0074] - Hue The yellowness of the polyolefin composition according to this embodiment in a state in which the silane-modified polyolefin is not contained is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less, taking into consideration the influence on a molded article obtained by adding the silane-modified polyolefin and melt-kneading it. The lower the yellowness, the better. Here, the yellowness is a value measured in accordance with JIS Z 8722:2009 after pelletizing the polyolefin composition not containing the silane-modified polyolefin.

[0075] <Molded Article> The molded article according to this embodiment is a molded article of a polyolefin composition containing a silane-modified polyolefin. As described above, the molded article may be obtained by melt-kneading a polyolefin, a zinc compound represented by formula (1) or formula (1)', and a silane-modified polyolefin, and molding the mixture by various molding methods. Examples of the various molding methods include extrusion molding, injection molding, and press molding.

[0076] The molded article according to this embodiment may be a silane-crosslinkable molded article containing a silane-modified polyolefin and a zinc compound represented by formula (1), and the zinc compound represented by formula (1) is preferably a zinc compound represented by formula (1)'.

[0077] In another aspect of the molded article according to the present embodiment, the molded article may be one obtained by melt-kneading a polyolefin, an unsaturated silane compound, and a radical generator, which are raw materials for the silane-modified polyolefin, and simultaneously carrying out the production of the silane-modified polyolefin by graft modification and the melt-kneading of the polyolefin and the zinc compound represented by formula (1) or (1)', followed by molding. In the above-mentioned another aspect, instead of melt-kneading the polyolefin and the zinc compound represented by formula (1) or (1)', the molded article may be one obtained by melt-kneading the polyolefin and a silanol condensation catalyst masterbatch containing the zinc compound represented by formula (1) or (1)', followed by molding.

[0078] <Silane-crosslinked molded article> The silane-crosslinked molded article according to this embodiment is a crosslinked molded article described in the above <Molded article>, such as a molded article obtained by molding a polyolefin composition containing a silane-modified polyolefin or a silane-crosslinkable molded article containing a silane-modified polyolefin and a zinc compound represented by formula (1) or formula (1)'. Specifically, for example, the molded article can be crosslinked by exposing it to a water atmosphere to promote a crosslinking reaction between silanol groups.

[0079] Various conditions can be used for the method of exposing to a water atmosphere, such as leaving the material still in air containing moisture, blowing air containing water vapor, immersing the material in a water bath, or spraying warm water in a mist.

[0080] In the crosslinking reaction between silanol groups, the hydrolyzable alkoxy groups in the silane-modified polyolefin react with water in the presence of the zinc compound represented by formula (1) or formula (1)' in the polyolefin composition to generate silanol groups through hydrolysis. The generated silanol groups then undergo dehydration condensation with each other, causing the crosslinking reaction to proceed, and the silane-modified polyolefins bond to each other to generate a silane-crosslinked polyolefin, resulting in a silane-crosslinked molded product.

[0081] The rate at which the crosslinking reaction proceeds depends on the conditions for exposure to the aqueous atmosphere, but typically it is sufficient to expose to the aqueous atmosphere at a temperature in the range of 20 to 130°C for 10 minutes to 2 weeks. Particularly preferred conditions are a temperature in the range of 60 to 110°C and a time in the range of 1 to 160 hours. When moisture-containing air is used as the method for exposure to the aqueous atmosphere, the relative humidity of the air is selected from the range of 1 to 100%.

[0082] The gel fraction (degree of crosslinking) of the silane-crosslinked molded product, which is a silane-crosslinked polyolefin, is the mass fraction of the insoluble portion after xylene boiling point extraction. Specifically, the silane-crosslinked molded product according to this embodiment is subjected to Soxhlet extraction with xylene, and then extracted with boiling xylene for 10 hours. The gel fraction can be determined by measuring the mass of the insoluble portion, i.e., the mass after drying, and calculating the ratio to the mass before extraction. More specifically, it is measured by the method described in the Examples section below.

[0083] The gel fraction is preferably 50% or more from the viewpoint of allowing the silane-crosslinked polyolefin to exhibit excellent properties over a long period of time. The upper limit of the gel fraction is not particularly limited, but is usually 100% (complete crosslinking) or less, and preferably 90% or less from the viewpoint of suppressing the progress of crosslinking during molding.

[0084] The gel fraction can be adjusted by changing the graft ratio (modification amount) of the unsaturated silane compound in the silane-modified polyolefin, the type and amount of the zinc compound represented by formula (1) or formula (1)' as the silanol condensation catalyst, the crosslinking conditions (temperature, time), etc.

[0085] The silane-crosslinked molded article according to this embodiment can be suitably used in various shapes and forms, such as wire coating materials, cable coating materials, pipes, hoses, tubes, various containers, sealing materials, films, and sheets.

[0086] In particular, the silane-crosslinked molded article according to this embodiment is preferably used as a coolant tube or a coolant tube member, and also preferably used as a lithium-ion battery separator or a lithium-ion battery separator member.

[0087] The present invention also relates to the use of the silane-crosslinked molded article. Specifically, examples of the use of the silane-crosslinked molded article according to this embodiment include use as a coolant tube, a coolant tube component, a lithium-ion battery separator, and a lithium-ion battery separator component.

[0088] The polyolefin composition, the silane-crosslinkable molded article, and the silane-crosslinkable molded article and use thereof according to this embodiment have been described in detail above. Another aspect of the present invention will be further described below.

[0089] A first aspect of the present invention is a polyolefin composition comprising a silanol condensation catalyst and a polyolefin, wherein the silanol condensation catalyst comprises a zinc compound represented by the following formula (1), and the content of the zinc compound in the polyolefin composition is 0.3 mass% or more: Zn(OCOR １ ) (OCOR ２ ) ... (1) (In formula (1), R １ and R ２ are each independently a saturated hydrocarbon group.

[0090] Aspect 2 of the present invention is the polyolefin composition of aspect 1, wherein R in formula (1) １ and R ２ are each independently a saturated hydrocarbon group having 5 to 15 carbon atoms.

[0091] Aspect 3 of the present invention is the polyolefin composition of aspect 2, wherein R in formula (1) １ and R２ are each independently a branched saturated hydrocarbon group having 5 to 15 carbon atoms.

[0092] A fourth aspect of the present invention is the polyolefin composition according to any one of the first to third aspects, wherein the content of the zinc compound in the silanol condensation catalyst is 10 to 100 mass %.

[0093] A fifth aspect of the present invention is the polyolefin composition according to any one of the first to fourth aspects, wherein the polyolefin comprises at least one selected from the group consisting of polyethylene and polypropylene.

[0094] A sixth aspect of the present invention is a masterbatch of the polyolefin composition according to any one of the first to fifth aspects.

[0095] In a seventh aspect of the present invention, the polyolefin composition of any one of the first to sixth aspects further comprises a silane-modified polyolefin.

[0096] An eighth aspect of the present invention is a molded article obtained by molding the polyolefin composition of the seventh aspect.

[0097] A ninth aspect of the present invention is a silane-crosslinked molded article obtained by crosslinking the molded article of the eighth aspect.

[0098] In a tenth aspect of the present invention, the silane-crosslinked molded article of the ninth aspect is a wire coating material, a cable coating material, a pipe, a hose, a tube, a container, a sealing material, a film, or a sheet.

[0099] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. The values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limit values ​​in the embodiments of the present invention, and a preferred range may be defined by a combination of the above upper or lower limit value and the value in the following examples or values ​​between the examples.

[0100] <Raw Materials> The raw materials used in the examples and comparative examples are shown below.

[0101] <Polyolefin> PO-1: Novatec (registered trademark) LD400 (manufactured by Japan Polyethylene Corporation, MFR: 2 g / 10 min, density: 0.92 g / cm ３ ) ; low-density polyethylene (LDPE) PO-2: Novatec (registered trademark) LD400P (manufactured by Japan Polyethylene Co., Ltd., MFR: 2 g / 10 min, density: 0.92 g / cm ３ ) ; low-density polyethylene (LDPE) PO-3: Novatec (registered trademark) UF240 (manufactured by Japan Polyethylene Co., Ltd., MFR: 2 g / 10 min, density: 0.92 g / cm ３ PO-4: Novatec (registered trademark) F30HG (manufactured by Japan Polyethylene Co., Ltd., MFR: 2 g / 10 min, density: 0.92 g / cm ３ PO-5: Novatec (registered trademark) HY350 (manufactured by Japan Polyethylene Co., Ltd., MFR: 3 g / 10 min, density: 0.95 g / cm ３ ) ; high density polyethylene (HDPE) PO-6: Novatec (registered trademark) HY350P (manufactured by Japan Polyethylene Co., Ltd., MFR: 5 g / 10 min, density: 0.95 g / cm ３ ); High density polyethylene (HDPE)

[0102] <Silanol Condensation Catalyst> C-1: K-KAT (registered trademark) XK-633 (manufactured by King Industries, zinc neodecanoate 100% by mass) * Corresponding to the zinc compound represented by formula (1) or formula (1)', where R in formula (1) or formula (1)' １ and R ２ are both branched alkyl groups having 10 carbon atoms. C-2: K-KAT (registered trademark) XK-672 (manufactured by King Industries, containing 85% by mass of zinc neodecanoate, 10% by mass of zirconium compound, and 4.5% by mass of 1-butanol) *Among the constituent components, zinc neodecanoate corresponds to the zinc compound represented by formula (1) or formula (1)', and R in formula (1) or formula (1') １ and R ２Both are branched alkyl groups having 10 carbon atoms. C-3: K-KAT (registered trademark) XK-640 (manufactured by King Industries, contains 50 to 60% by mass of bismuth carboxylate, less than 1.5% by mass of mineral oil, and 38.5 to 50% by mass of other components) *Does not contain zinc compounds. C-4: K-KAT (registered trademark) K-670 (manufactured by King Industries, contains 10 to less than 20% by mass of alkylamine, 1 to less than 3% by mass of zinc compound, and 80 to less than 90% by mass of other components).

[0103] Other Components: A-1: ​​Irganox (registered trademark) 1010 (manufactured by BASF); antioxidant; A-2: Irganox (registered trademark) MD1024 (manufactured by BASF); metal deactivator; A-3: Sumilizer (registered trademark) WXRC (manufactured by Sumitomo Chemical Co., Ltd.); antioxidant; A-4: Viton (registered trademark) Freeflow RC (manufactured by DuPont); lubricant.

[0104] Silane-modified polyolefin: Linklon XLE830N (manufactured by Mitsubishi Chemical Corporation: MFR: 0.4 g / 10 min, density: 0.93 g / cm ３ ) silane-modified linear low-density polyethylene (LLDPE).

[0105] <Measurement and Evaluation Methods> <Measurement of Polyolefin Composition> Melt Flow Rate (MFR) The MFR of the pelletized polyolefin composition was measured at 190°C and a load of 21.2 N in accordance with JIS K 7210: 1999. The results are shown in Table 1.

[0106] Color (Yellowness Index (YI) of Pellet) The yellowness index of the pelletized polyolefin composition was measured with reference to JIS Z 8722:2009. Here, taking into consideration the influence on a molded article obtained by melt-kneading the polyolefin composition and the silane-modified polyolefin, a yellowness index of 20 or less can be considered good (passed). The results are shown in Table 1.

[0107] Odor 80 g of the polyolefin composition was placed in a 500 mL Erlenmeyer flask with a stopper, the flask was stopped, and the flask was left to stand for 24 hours in a thermostatic chamber at 23°C and 50% RH. Five inspectors then checked the odor within 10 minutes of opening the stopper, and each inspector gave a score based on the following criteria. The average score of the five inspectors is shown in Table 1. The odor is considered good (passed) if the average score is 4.0 points or less, and the lower the score, the more preferable it is. (Criteria) 0 points: Odorless 1 point: Odor that can barely be detected (detection threshold concentration) 2 points: Weak odor that can be identified (recognition threshold concentration) 3 points: Odor that can be easily detected 4 points: Strong odor 5 points: Intense odor

[0108] <<Measurements of Silane-Crosslinked Molded Product>> Gel Fraction A sheet (thickness: 2 mm) of the silane-crosslinked molded product was subjected to Soxhlet extraction in boiling xylene at 144°C for 10 hours, and the undissolved resin was dried and then measured for its mass. The gel fraction was calculated as a percentage of the mass of the sheet of the silane-crosslinked molded product before Soxhlet extraction. A gel fraction of 50% or more was considered good (passed). The results are shown in Table 1.

[0109] Example 1-1a The raw material composition shown in Table 1, i.e., 50 parts by mass of PO-1, 50 parts by mass of PO-2, 5 parts by mass of C-1, 2 parts by mass of A-1, 1 part by mass of A-2, 1 part by mass of A-3, and 0.3 parts by mass of A-4, was mixed in a blender. The mixture was then charged into a twin-screw kneader (TEX25-αIII, manufactured by JSW Co., Ltd.) set at 180°C, and the strands emerging from the nozzle were cooled and solidified in a water bath, after which they were cut into pellets to obtain a masterbatched polyolefin composition A. The MFR, hue, and odor of the obtained polyolefin composition A were measured according to the methods described above. The results are shown in Table 1. Furthermore, blanks in the raw material composition in Table 1 indicate that no compound was blended.

[0110] Example 1-1b 5 parts by mass of polyolefin composition A was added as a catalyst masterbatch to 100 parts by mass of silane-modified polyolefin Linklon XLE830N, and the mixture was dry-blended. The mixture was then placed in an injection molding machine and molded into a 2 mm-thick sheet at 220°C, yielding a molded article of polyolefin composition A' further containing silane-modified polyolefin.

[0111] Example 2-1 A sheet-shaped molded product of polyolefin composition A' containing the silane-modified polyolefin obtained in Example 1-1b was left to stand in a thermo-hygrostat at 85°C and 85% RH for 16 hours to obtain a sheet-shaped silane-crosslinked molded product A. The gel fraction of the obtained sheet-shaped silane-crosslinked molded product A was measured according to the method described above. The results are shown in Table 1.

[0112] Examples 1-2a to 1-10a, Comparative Example 1-1a Polyolefin compositions B to K were obtained in the same manner as in Example 1-1a, except that the raw material blends shown in Table 1 were used. The MFR, hue, and odor of the obtained polyolefin compositions B to K were measured in the same manner as in Example 1-1a. The results are shown in Table 1. In Table 1, the zinc content of Comparative Example 1-1a is marked "-". This is because the structure of the silanol condensation catalyst C-4 used could not be identified and therefore could not be calculated. The tin content of polyolefin compositions A to K of Examples 1-1a to 1-10a was all less than 100 ppm by mass.

[0113] Examples 1-2b to 1-10b, Comparative Example 1-1b Instead of polyolefin composition A, the polyolefin compositions B to K obtained in Examples 1-2a to 1-10a and Comparative Example 1-1a were used, and molded articles of polyolefin compositions B' to K' containing silane-modified polyolefin were obtained in the same manner as in Example 1-1b.

[0114] Examples 2-1 to 2-10, Comparative Example 2-1 Sheet-like silane-crosslinked molded articles B to K were obtained in the same manner as in Example 2-1, except that sheet-like molded articles of polyolefin compositions B' to K' containing silane-modified polyolefin obtained in Examples 1-2b to 1-10b and Comparative Example 1-1b were used instead of the sheet-like molded article of polyolefin composition A' containing silane-modified polyolefin. The gel fractions of the obtained sheet-like silane-crosslinked molded articles B to K were measured in the same manner as in Example 2-1. The results are shown in Table 1.

[0115]

[0116] As shown in Table 1, the olefin compositions A to J according to this embodiment were superior in the evaluation results of both hue (yellowness index) and odor, with the yellowness index being particularly low, compared with the olefin composition K. Furthermore, the sheet-like silane-crosslinked molded products A to J, which were obtained by crosslinking a silane-modified polyolefin using the olefin compositions A to J, all exhibited a high level of gel fraction, confirming that the olefin compositions A to J have good crosslinking performance.

[0117] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2023-004649) filed on January 16, 2023, the contents of which are incorporated herein by reference.

Claims

1. A polyolefin composition comprising a zinc compound represented by the following formula (1)' and a polyolefin. Zn(OCO-R １ )(OCO-R ２ )... (1)' (In formula (1)', R １ and R ２ are each independently a saturated hydrocarbon group having 9 to 11 carbon atoms with a branch.) 2. The polyolefin composition according to claim 1, wherein the tin content is less than 100 ppm by mass.

3. The polyolefin composition according to claim 1 or 2, wherein the zinc content is 0.10% by mass or more.

4. The polyolefin composition according to claim 3, wherein the zinc content is 3.0% by mass or less.

5. The polyolefin composition according to claim 1 or 2, comprising at least one selected from the group consisting of polyethylene and polypropylene as the polyolefin.

6. The polyolefin composition according to claim 1 or 2, which is a catalyst masterbatch.

7. The polyolefin composition according to claim 1 or 2, further comprising a silane-modified polyolefin.

8. A silane crosslinkable molded article comprising a silane-modified polyolefin and a zinc compound represented by the following formula (1)'. Zn(OCOR １ )(OCOR ２ )... (1)' (In formula (1)', R １ and R ２ are each independently a saturated hydrocarbon group having 9 to 11 carbon atoms with a branch.) 9. A silane crosslinked molded article obtained by crosslinking the silane crosslinkable molded article according to claim 8.

10. The silane crosslinked molded article according to claim 9, which is an electric wire coating material, a cable coating material, a pipe, a hose, a tube, a container, a sealing material, a film, or a sheet.

11. The silane crosslinked molded article according to claim 9, which is a coolant tube.

12. The silane crosslinked molded article according to claim 9, which is a coolant tube member.

13. The silane crosslinked molded article according to claim 9, which is a lithium ion battery separator.

14. The silane crosslinked molded article according to claim 9, which is a lithium ion battery separator member.

15. Use of the silane crosslinked molded article according to claim 9 as a coolant tube.

16. Use of the silane crosslinked molded article according to claim 9 as a coolant tube member.

17. Use of the silane crosslinked molded article according to claim 9 as a lithium ion battery separator.

18. Use of the silane crosslinked molded article according to claim 9 as a lithium ion battery separator member.

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