Molded body, rubber product, and resin product

Abstract

The present invention addresses the problem of providing a molded body that exhibits improved durability, shape restorability, and self-repairability as compared to when being non-crosslinked, while maintaining elongation and stress at levels equivalent to those when being non-crosslinked. A solution to the problem is a molded body that contains a copolymer having a conjugated diene unit and a non-conjugated olefin unit, and that has been subjected to electron beam crosslinking.

Description

Molded products, rubber products, and resin products

[0001] This disclosure relates to molded articles, rubber products, and resin products.

[0002] Conventionally, various studies have been conducted to improve the performance of rubber products and the like. For example, Patent Document 1 discloses a rubber composition containing a rubber component (a) which includes a multi-component copolymer (a1) containing conjugated diene units, non-conjugated olefin units, and aromatic vinyl units, and a softening agent (b).

[0003] International Publication No. 2019 / 116656

[0004] In rubber compositions such as those disclosed in Patent Document 1, a network structure of the copolymer is formed by sulfur crosslinking. However, sulfur crosslinking and peroxide crosslinking have the problem that elongation and stress are reduced compared to the case of uncrosslinked materials. Furthermore, in molded articles containing copolymers having conjugated diene units and unconjugated olefin units, improvements in performance such as durability, shape recovery, and self-healing properties are required depending on the application.

[0005] Therefore, this disclosure aims to solve the problems of the above-mentioned prior art and provide a molded article that maintains elongation and stress at the same level as the uncrosslinked case, while improving durability, shape recovery, and self-healing properties compared to the uncrosslinked case. Furthermore, this disclosure aims to provide rubber products and resin products using such a molded article.

[0006] The gist of this disclosure, which addresses the above issues, is as follows:

[0007] [1] A molded article comprising a copolymer having conjugated diene units and non-conjugated olefin units, which is subjected to electron beam crosslinking.

[0008] [2] The molded article according to [1], wherein the copolymer has a melting point of 50 to 120°C.

[0009] [3] The molded article according to [1] or [2], wherein the copolymer has a content of conjugated diene units that is greater than 0 mol% and less than or equal to 50 mol%, and a content of unconjugated olefin units that is 50 mol% or more and less than 100 mol%.

[0010] [4] The molded article according to any one of [1] to [3], wherein the copolymer further comprises aromatic vinyl units.

[0011] [5] The molded article according to any one of [1] to [4], wherein the dose of electron beam irradiation for electron beam crosslinking is greater than 0 kGy and less than or equal to 500 kGy.

[0012] [6] The molded article according to any one of [1] to [5], wherein the crosslinking agent content is 1 part by mass or less per 100 parts by mass of the copolymer.

[0013] [7] A molded article according to any one of [1] to [6], further comprising a fatty acid and a filler.

[0014] [8] A rubber product using a molded body as described in any of [1] to [7].

[0015] [9] A resin product using a molded article described in any of [1] to [7].

[0016] According to this disclosure, it is possible to provide a molded article that maintains elongation and stress at the same level as the uncrosslinked case, while improving durability, shape recovery, and self-healing properties compared to the uncrosslinked case. According to the present invention, it is possible to provide rubber products and resin products using such a molded article.

[0017] Figure 1 shows graphs of stress and elongation evaluation in the embodiment.

[0018] The molded articles, rubber products, and resin products of this disclosure will be described in detail below based on their embodiments.

[0019] The compounds described herein may be derived in part or in whole from fossil resources, from biological resources such as plant resources, or from recycled resources such as used tires. They may also be derived from a mixture of two or more of fossil resources, biological resources, or recycled resources.

[0020] <Molded Article> The molded article of this embodiment is characterized by containing a copolymer having conjugated diene units and non-conjugated olefin units, and being subjected to electron beam crosslinking. The above molded article maintains elongation and stress at the same level as the uncrosslinked case, while improving durability, shape recovery, and self-healing properties compared to the uncrosslinked case. When sulfur crosslinking or peroxide crosslinking is performed, elongation and stress decrease significantly compared to the uncrosslinked case. This is because sulfur crosslinking and peroxide crosslinking require the addition of crosslinking chemicals such as crosslinking agents and vulcanization accelerators, and it is thought that these components remain in the molded article after crosslinking, reducing stress and elongation. On the other hand, in the case of electron beam crosslinking, it is not necessary to add crosslinking chemicals, and crosslinking can be performed by irradiation with an electron beam, so it is thought that the effect of the copolymer is not hindered and the decrease in stress and elongation can be suppressed at the same level as the uncrosslinked case. Furthermore, since a network structure can be formed by electron beam crosslinking, it is thought that durability, shape recovery, and self-healing properties are improved compared to the uncrosslinked case. In addition, it has become clear from the results of this study that irradiation with an electron beam tends to result in a lower temperature for the peak top of the melting point of the crystal. This suggests that the crosslinked structure introduced by electron beams affects the crystallization of ethylene units, and that this effect depends on the electron beam irradiation dose, i.e., the degree of crosslinking. Furthermore, since the number of carbon-hydrogen bonds in the copolymer decreases compared to sulfur crosslinking and peroxide crosslinking after electron beam irradiation, it is suggested that electron beam crosslinking consumes carbon-hydrogen sites to form the crosslinked structure. It is thought that these differences in the crosslinking structure formation mechanism led to changes (improvements) in various physical properties.

[0021] (Copolymer having conjugated diene units and non-conjugated olefin units) The molded article of this embodiment includes a copolymer having conjugated diene units and non-conjugated olefin units (hereinafter sometimes simply referred to as "polymer"). Furthermore, the copolymer having conjugated diene units and non-conjugated olefin units may be a binary copolymer consisting of two units, a conjugated diene unit and a non-conjugated olefin unit, or a ternary copolymer consisting of three units including an aromatic vinyl unit, or a polypolymer including other monomer units.

[0022] - Conjugated diene unit - The conjugated diene unit is a structural unit derived from a conjugated diene compound as a monomer. Here, the conjugated diene compound refers to a conjugated diene compound. The conjugated diene compound preferably has 4 to 8 carbon atoms. Specific examples of such conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and the like. The conjugated diene compound may be a single type alone or a combination of two or more types.

[0023] From the perspective of improving the mechanical strength of the molded body, the conjugated diene compound as a monomer of the copolymer preferably contains at least one selected from the group consisting of 1,3-butadiene and isoprene, more preferably consists of only at least one selected from the group consisting of 1,3-butadiene and isoprene, and even more preferably consists of only 1,3-butadiene. In other words, the conjugated diene unit in the copolymer preferably contains at least one selected from the group consisting of 1,3-butadiene units and isoprene units, more preferably consists of only at least one selected from the group consisting of 1,3-butadiene units and isoprene units, and even more preferably consists of only 1,3-butadiene units.

[0024] When the copolymer is a binary copolymer, the content of the conjugated diene unit is preferably more than 0 mol% and 50 mol% or less. In this case, a copolymer excellent in elongation and weather resistance can be obtained. From the same perspective, the ratio of the conjugated diene unit in the binary copolymer is more preferably 40 mol% or less.

[0025] In a binary copolymer, the proportion of 1,2 adducts (including 3,4 adducts) of conjugated diene units is preferably 10 mol% or less. A proportion of 10 mol% or less improves the heat resistance and flexural fatigue resistance of the copolymer. From a similar viewpoint, the proportion of 1,2 adducts (including 3,4 adducts) of conjugated diene units in a binary copolymer is more preferably 8 mol% or less, and even more preferably 6 mol% or less. Note that the proportion of 1,2 adducts (including 3,4 adducts) of conjugated diene units refers to the proportion of all conjugated diene units, not the proportion of the entire copolymer. Furthermore, when the conjugated diene units are butadiene units, the proportion has the same meaning as the amount of 1,2-vinyl bonds.

[0026] When the copolymer is a ternary copolymer or a polypolymer, the content of conjugated diene units is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 37 mol% or less. The flexibility and mechanical strength of the molded article can be improved by having a conjugated diene unit content of 1 to 50 mol% of the total copolymer. From the viewpoint of further improving the flexibility and mechanical strength of the molded article, the content of conjugated diene units is preferably in the range of 1 to 50 mol% of the total copolymer, more preferably in the range of 3 to 40 mol%, and even more preferably in the range of 5 to 37 mol%.

[0027] - Non-conjugated olefin unit - The non-conjugated olefin unit is a constituent unit derived from a non-conjugated olefin compound as a monomer. Here, a non-conjugated olefin compound refers to an aliphatic unsaturated hydrocarbon having one or more carbon-carbon double bonds. The non-conjugated olefin compound preferably has 2 to 10 carbon atoms. Specific examples of such non-conjugated olefin compounds include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, and heteroatom-substituted alkene compounds such as vinyl pivalate, 1-phenylthioethene, and N-vinylpyrrolidone. The non-conjugated olefin compound may be a single compound or a combination of two or more compounds.

[0028] The non-conjugated olefin compound as a monomer of the copolymer is preferably an acyclic non-conjugated olefin compound from the viewpoint of improving the mechanical strength of the molded article, and the acyclic non-conjugated olefin compound is more preferably an α-olefin, even more preferably an α-olefin containing ethylene, and particularly preferably consisting only of ethylene. In other words, the non-conjugated olefin unit in the copolymer is preferably an acyclic non-conjugated olefin unit, and the acyclic non-conjugated olefin unit is more preferably an α-olefin unit, even more preferably an α-olefin unit containing ethylene units, and particularly preferably consisting only of ethylene units.

[0029] When the copolymer is a binary copolymer, the content of non-conjugated olefin units is preferably 50 mol% or more and less than 100 mol%. In this case, the fracture characteristics of the molded article at high temperatures can be effectively improved. From a similar viewpoint, the proportion of non-conjugated olefin units in the binary copolymer is more preferably 60 mol% or more.

[0030] When the copolymer is a ternary copolymer or a polypolymer, the content of non-conjugated olefin units is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 55 mol% or more, particularly preferably 60 mol% or more, and also preferably 97 mol% or less, more preferably 95 mol% or less, and even more preferably 90 mol% or less. The mechanical strength of the molded article can be improved by having a non-conjugated olefin unit content of 40 to 97 mol% of the entire copolymer. From the viewpoint of further improving the mechanical strength of the molded article, the non-conjugated olefin unit content is preferably in the range of 40 to 97 mol% of the entire copolymer, more preferably in the range of 45 to 95 mol%, even more preferably in the range of 55 to 90 mol%, and even more preferably in the range of 60 to 90 mol%.

[0031] - Aromatic vinyl units - The copolymer preferably further contains aromatic vinyl units. Aromatic vinyl units are constituent units derived from aromatic vinyl compounds as monomers. By containing aromatic vinyl units, the copolymer can cleave crystalline components such as ethylene crystal components, suppressing excessive crystallization derived from non-conjugated olefin units, thereby improving the rigidity of the copolymer while minimizing the impairment of elasticity and achieving high durability, thus improving the durability of the molded article. Here, aromatic vinyl compounds refer to aromatic compounds substituted with at least vinyl groups and are not included in conjugated diene compounds. The aromatic vinyl compounds preferably have 8 to 10 carbon atoms. Examples of such aromatic vinyl compounds include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, and p-ethylstyrene. The aromatic vinyl compounds may be used alone or in combination of two or more types.

[0032] The aromatic vinyl compound used as the monomer of the copolymer preferably contains styrene, and more preferably consists solely of styrene, from the viewpoint of improving the mechanical strength of the molded article. In other words, the aromatic vinyl units in the copolymer preferably contain styrene units, and more preferably consist solely of styrene units. Note that the aromatic ring in the aromatic vinyl unit is not included in the main chain of the copolymer unless it is bonded to an adjacent unit.

[0033] When the copolymer is a ternary copolymer or a polypolymer, the content of aromatic vinyl units is preferably 2 mol% or more, more preferably 35 mol% or less, more preferably 30 mol% or less, and even more preferably 25 mol% or less. The mechanical strength of the molded article can be improved by having an aromatic vinyl unit content of 2 to 35 mol% of the total copolymer. From the viewpoint of further improving the mechanical strength of the molded article, the content of aromatic vinyl units is preferably in the range of 2 to 35 mol% of the total copolymer, more preferably in the range of 2 to 30 mol%, and even more preferably in the range of 2 to 25 mol%.

[0034] From the viewpoint of obtaining the desired effects of the present invention, the content of other constituent units other than conjugated diene units, non-conjugated olefin units, and aromatic vinyl units is preferably 30 mol% or less of the total copolymer, more preferably 20 mol% or less, even more preferably 10 mol% or less, and particularly preferably none, i.e., a content of 0 mol%. In other words, the copolymer is preferably a binary copolymer consisting of two units, a conjugated diene unit and a non-conjugated olefin unit, or a ternary copolymer consisting of three units, a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit. Furthermore, from the viewpoint of reliably obtaining the desired effects, the copolymer is preferably 0 mol% in content of butylene units.

[0035] From the viewpoint of improving the mechanical strength of the molded article, the copolymer is preferably a polymer obtained by polymerizing at least one type of conjugated diene compound, one type of non-conjugated olefin compound, and one type of aromatic vinyl compound as monomers. In other words, the copolymer is preferably a copolymer containing one type of conjugated diene unit, one type of non-conjugated olefin unit, and one type of aromatic vinyl unit; more preferably a ternary copolymer consisting only of one type of conjugated diene unit, one type of non-conjugated olefin unit, and one type of aromatic vinyl unit; and even more preferably a ternary copolymer consisting only of 1,3-butadiene units, ethylene units, and styrene units. Here, "one type of conjugated diene unit" includes conjugated diene units with different bonding modes.

[0036] In the case of a binary copolymer, for example, it is preferable that the content of conjugated diene units is greater than 0 mol% and less than or equal to 50 mol%, and the content of non-conjugated olefin units is greater than or equal to 50 mol% and less than 100 mol%. In this case, a copolymer with excellent elongation and weather resistance can be obtained, and the fracture characteristics of the molded article at high temperatures can be effectively improved.

[0037] Furthermore, if the copolymer is, for example, a ternary copolymer, it is preferable that the content of conjugated diene units is 1 to 50 mol%, the content of unconjugated olefin units is 40 to 97 mol%, and the content of aromatic vinyl units is 2 to 35 mol%. In this case, the flexibility and mechanical strength of the molded article can be improved.

[0038] - Physical properties of the copolymer - The copolymer preferably has a number-average molecular weight (Mn) on a polystyrene basis of 10,000 to 9,000,000 (10 to 9,000 kg / mol), and more preferably 100,000 to 8,000,000 (100 to 8,000 kg / mol). When the Mn of the copolymer is 10,000 or more, the mechanical strength of the molded article can be sufficiently ensured, and when the Mn is 9,000,000 or less, the workability of the copolymer itself or the composition containing the copolymer is less likely to be impaired.

[0039] The copolymer preferably has a weight-average molecular weight (Mw) on a polystyrene basis of 10,000 to 10,000,000 (10 to 10,000 kg / mol), more preferably 50,000 to 9,000,000 (50 to 9,000 kg / mol), and even more preferably 100,000 to 8,000,000 (100 to 8,000 kg / mol). A Mw of 10,000 or more ensures sufficient mechanical strength of the molded article, while a Mw of 10,000,000 or less makes it less likely to impair the workability of the copolymer itself or the composition containing the copolymer.

[0040] The copolymer preferably has a molecular weight distribution [Mw / Mn (weight-average molecular weight / number-average molecular weight)] of 1.00 to 4.00, more preferably 1.00 to 3.50, and even more preferably 1.80 to 3.00. If the molecular weight distribution of the copolymer is 4.00 or less, sufficient homogeneity can be provided to the physical properties of the copolymer.

[0041] The number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) of the copolymer are determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0042] The copolymer preferably has an endothermic peak energy of 10 to 150 J / g, and more preferably 30 to 120 J / g, as measured by a differential scanning calorimeter (DSC) at 0 to 120°C. If the endothermic peak energy of the copolymer is 10 J / g or higher, the crystallinity of the copolymer is increased, and the crack resistance of the molded article can be improved. Furthermore, if the endothermic peak energy of the copolymer is 150 J / g or lower, the workability of the copolymer itself or the composition containing the copolymer is improved. The endothermic peak energy of the copolymer can be measured using a differential scanning calorimeter in accordance with JIS K 7121-1987, for example, by raising the temperature from -150°C to 150°C at a heating rate of 10°C / min.

[0043] The copolymer preferably has a melting point of 50 to 120°C, and more preferably 50 to 110°C. If the melting point of the copolymer is 50°C or higher, the crystallinity of the copolymer is increased, and the durability of the molded article can be improved. If the melting point of the copolymer is 120°C or lower, the workability of the copolymer itself or the composition containing the copolymer is improved. Furthermore, if the melting point of the copolymer is 50 to 120°C, the durability of the molded article is high, and the workability in the manufacture of the molded article is improved. The melting point of the copolymer may be measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121-1987.

[0044] The copolymer preferably has a glass transition temperature (Tg) of 0°C or lower, as measured by a differential scanning calorimeter (DSC), and more preferably between -110°C and -10°C. If the glass transition temperature of the copolymer is 0°C or lower, the mechanical strength of the molded article can be further improved. The glass transition temperature of the copolymer may be measured using a differential scanning calorimeter in accordance with JIS K 7121-1987.

[0045] The copolymer preferably has a degree of crystallinity of 0.5 to 50%, more preferably 3 to 45%, and even more preferably 5 to 45%. If the degree of crystallinity of the copolymer is 0.5% or higher, sufficient crystallinity of the copolymer due to non-conjugated olefin units can be ensured, further improving the mechanical strength of the molded article. If the degree of crystallinity of the copolymer is 50% or lower, the workability during kneading of the copolymer itself or a composition containing the copolymer, and the extrusion processability are improved. The degree of crystallinity of the copolymer can be calculated by measuring the crystalline melting energy of 100% crystalline polyethylene and the melting peak energy of the copolymer, and then calculating the degree of crystallinity from the energy ratio of polyethylene to copolymer. The melting peak energy can be measured using a differential scanning calorimeter.

[0046] Preferably, the main chain of the copolymer consists solely of acyclic structures. This further improves the mechanical strength of the molded article. NMR is the primary measurement method used to confirm whether or not the main chain of the copolymer has a cyclic structure. Specifically, if no peaks originating from the cyclic structure present in the main chain (for example, peaks appearing at 10-24 ppm for three-membered to five-membered rings) are observed, it indicates that the main chain of the copolymer consists solely of acyclic structures. In this specification, the main chain of a polymer refers to a linear molecular chain in which all other molecular chains (long molecular chains, short molecular chains, or both) are linked together like a pendant [Glossary of Basic Terms in Polymer Science IUPAC Recommendations 1996, Pure Appl. Chem.]. See Section 1.34 of 68, 2287-2311 (1996). The copolymer may have either a linear or branched structure, but a linear structure is preferred.

[0047] The copolymer exhibits excellent mechanical strength, specifically in terms of breaking strength, puncture strength, tensile strength, abrasion resistance, crack resistance, and impact resistance. The copolymer also exhibits excellent mechanical strength at low temperatures. Furthermore, because the copolymer exhibits excellent mechanical strength without relying on fillers such as carbon black or silica, it can be colored using colorants, offering excellent decorative properties. On the other hand, since the copolymer can interact with fillers, its mechanical strength can be further improved by using fillers. Because the copolymer contains conjugated diene units, it is crosslinkable. Because the copolymer contains conjugated diene units, it acts as an elastic material and is stretchable. The copolymer can be injection molded and stretched, allowing it to be processed into a film. Because the copolymer contains both conjugated diene units and non-conjugated olefin units, it readily adheres to both resins (olefin resins) and rubbers (diene-based rubbers), and therefore can function as an adhesive between resins and rubbers. Additionally, the copolymer can be foamed. As described above, the copolymer preferably has a melting point of 50 to 120°C, and its shape can be restored by heating it by pouring hot water at about 80 to 100°C over it or by immersing it in hot water. Furthermore, the copolymer has shape memory properties.

[0048] -Method for producing copolymers- When producing a binary copolymer consisting of two units, a conjugated diene unit and a non-conjugated olefin unit, the copolymer can be produced by a polymerization step using a conjugated diene compound and a non-conjugated olefin compound as monomers. Furthermore, when producing a ternary copolymer consisting of three units, a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, the copolymer can be produced by a polymerization step using a conjugated diene compound, a non-conjugated olefin compound, and an aromatic vinyl compound as monomers.

[0049] The method for producing the copolymer may further include a coupling step, a washing step, and other steps as necessary. The method for producing the copolymer will be described below, with the production of a ternary copolymer being a representative example.

[0050] In the production of copolymers, it is preferable to add only the non-conjugated olefin compound and the aromatic vinyl compound in the presence of a polymerization catalyst, without adding the conjugated diene compound, and to polymerize them first. In particular, when using the catalyst composition described later, the conjugated diene compound is more reactive than the non-conjugated olefin compound and the aromatic vinyl compound, making it difficult to polymerize either or both of the non-conjugated olefin compound and the aromatic vinyl compound in the presence of the conjugated diene compound. Furthermore, polymerizing the conjugated diene compound first and then additionally polymerizing the non-conjugated olefin compound and the aromatic vinyl compound is also often difficult due to the characteristics of the catalyst.

[0051] Any polymerization method can be used, such as solution polymerization, suspension polymerization, liquid-phase bulk polymerization, emulsion polymerization, gas-phase polymerization, or solid-phase polymerization. Furthermore, if a solvent is used in the polymerization reaction, any solvent that is inert in the polymerization reaction is acceptable, such as toluene, cyclohexane, or n-hexane.

[0052] The polymerization process may be carried out in one step or in two or more steps. A one-step polymerization process is a process in which all types of monomers to be polymerized, namely conjugated diene compounds, non-conjugated olefin compounds, aromatic vinyl compounds, and other monomers, preferably conjugated diene compounds, non-conjugated olefin compounds, and aromatic vinyl compounds, are reacted simultaneously to polymerize them. A multi-step polymerization process is a process in which some or all of one or two types of monomers are reacted first to form a polymer (first polymerization step), and then one or more steps (second polymerization step to final polymerization step) are carried out in which monomers of the type not added in the first polymerization step, the remainder of the monomers added in the first polymerization step, etc., are added and polymerized. In particular, in the production of the copolymer, it is preferable to carry out the polymerization process in multiple steps.

[0053] In the polymerization process, the polymerization reaction is preferably carried out under an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The temperature of the polymerization reaction is not particularly limited, but for example, it is preferably in the range of -100°C to 200°C, and can also be around room temperature. The pressure of the polymerization reaction is preferably in the range of 0.1 to 10.0 MPa in order to sufficiently incorporate the conjugated diene compound into the polymerization reaction system. The reaction time of the polymerization reaction is also not particularly limited, but for example, it is preferably in the range of 1 second to 10 days, but can be appropriately selected depending on conditions such as the type of polymerization catalyst and polymerization temperature. Furthermore, in the polymerization process of the conjugated diene compound, polymerization may be stopped using polymerization stoppers such as methanol, ethanol, or isopropanol.

[0054] The polymerization process is preferably carried out in multiple stages. More preferably, it is preferable to carry out a first step of mixing a first monomer raw material containing at least an aromatic vinyl compound with a polymerization catalyst to obtain a polymerization mixture, and a second step of introducing a second monomer raw material containing at least one selected from the group consisting of conjugated diene compounds, non-conjugated olefin compounds, and aromatic vinyl compounds into the polymerization mixture. Furthermore, it is even more preferable that the first monomer raw material does not contain a conjugated diene compound and the second monomer raw material contains a conjugated diene compound.

[0055] The first monomer raw material used in the first step may contain a non-conjugated olefin compound along with the aromatic vinyl compound. Furthermore, the first monomer raw material may contain the entire amount of the aromatic vinyl compound used, or only a portion of it. In addition, the non-conjugated olefin compound is contained in at least one of the first monomer raw material and the second monomer raw material.

[0056] The first step is preferably carried out in a reactor under the atmosphere of an inert gas, preferably nitrogen gas or argon gas. The temperature (reaction temperature) in the first step is not particularly limited, but is preferably in the range of -100°C to 200°C, and can also be around room temperature. The pressure in the first step is not particularly limited, but is preferably in the range of 0.1 to 10.0 MPa in order to sufficiently incorporate the aromatic vinyl compound into the polymerization reaction system. The time spent in the first step (reaction time) can be appropriately selected depending on the type of polymerization catalyst, reaction temperature, and other conditions, but for example, when the reaction temperature is 25 to 80°C, it is preferably in the range of 5 to 500 minutes.

[0057] In the first step, any polymerization method can be used to obtain the polymerization mixture, such as solution polymerization, suspension polymerization, liquid-phase bulk polymerization, emulsion polymerization, gas-phase polymerization, or solid-phase polymerization. Furthermore, if a solvent is used in the polymerization reaction, any solvent that is inert in the polymerization reaction is acceptable, such as toluene, cyclohexanone, or n-hexane.

[0058] The second monomer raw material used in the second step is preferably a conjugated diene compound alone, or a conjugated diene compound and a non-conjugated olefin compound, or a conjugated diene compound and an aromatic vinyl compound, or a conjugated diene compound, a non-conjugated olefin compound and an aromatic vinyl compound. If the second monomer raw material includes at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound in addition to a conjugated diene compound, these monomer raw materials may be mixed with a solvent beforehand and then introduced into the polymerization mixture, or each monomer raw material may be introduced individually. Furthermore, each monomer raw material may be added simultaneously or sequentially. In the second step, there are no particular restrictions on the method of introducing the second monomer raw material to the polymerization mixture, but it is preferable to control the flow rate of each monomer raw material and add them continuously to the polymerization mixture (so-called metering). In this case, when using monomer raw materials that are gaseous under the conditions of the polymerization reaction system (for example, ethylene as a non-conjugated olefin compound under room temperature and atmospheric pressure), they can be introduced into the polymerization reaction system at a predetermined pressure.

[0059] The second step is preferably carried out in a reactor under an atmosphere of inert gas, preferably nitrogen gas or argon gas. The temperature in the second step (reaction temperature) is not particularly limited, but for example, a range of -100°C to 200°C is preferred, and it can also be around room temperature. Note that raising the reaction temperature may reduce the selectivity of the cis-1,4 bond in the conjugated diene unit. The pressure in the second step is not particularly limited, but a range of 0.1 to 10.0 MPa is preferred in order to sufficiently incorporate monomers such as conjugated diene compounds into the polymerization reaction system. The time spent in the second step (reaction time) can be appropriately selected depending on conditions such as the type of polymerization catalyst and reaction temperature, but for example, a range of 0.1 hours to 10 days is preferred. In the second step, the polymerization reaction may be stopped using a polymerization stopper such as methanol, ethanol, or isopropanol.

[0060] Here, the polymerization steps of the conjugated diene compound, unconjugated olefin compound, and aromatic vinyl compound described above preferably include a step of polymerizing the various monomers in the presence of one or more of the following components (a) to (f) as catalyst components. It is preferable to use one or more of the following components (a) to (f) in the polymerization step, but it is even more preferable to use a combination of two or more of the following components (a) to (f) as a catalyst composition. (a) Component: Rare earth element compound or reaction product of said rare earth element compound with a Lewis base (b) Component: Organometallic compound (c) Component: Aluminoxane (d) Component: Ionic compound (e) Component: Halogen compound (f) Component: Cyclopentadiene skeleton-containing compound selected from substituted or unsubstituted cyclopentadiene (compound having a cyclopentadienyl group), substituted or unsubstituted indene (compound having an indenyl group), and substituted or unsubstituted fluorene (compound having a fluorenyl group). Components (a) to (f) above can be used in polymerization steps by referring, for example, to International Publication No. 2018 / 092733.

[0061] The coupling step is a step in which a reaction (coupling reaction) is carried out to modify at least a portion (e.g., the ends) of the polymer chain of the copolymer obtained in the polymerization step. In the coupling step, it is preferable to carry out the coupling reaction when the polymerization reaction reaches 100%. There are no particular restrictions on the coupling agent used in the coupling reaction, and it can be appropriately selected according to the purpose. Examples include tin-containing compounds such as bis(1-octadecyl maleate) dioctyltin(IV); isocyanate compounds such as 4,4'-diphenylmethane diisocyanate; and alkoxysilane compounds such as glycidylpropyltrimethoxysilane. These may be used individually or in combination of two or more. Among these, bis(1-octadecyl maleate) dioctyltin(IV) is preferred in terms of reaction efficiency and low gel formation. It should be noted that the number-average molecular weight (Mn) of the copolymer can be increased by carrying out the coupling reaction.

[0062] The washing step is a process of washing the copolymer obtained in the polymerization step. There are no particular restrictions on the medium used for washing, and it can be appropriately selected depending on the purpose. Examples include methanol, ethanol, isopropanol, etc. However, when using a catalyst derived from a Lewis acid as the polymerization catalyst, an acid (e.g., hydrochloric acid, sulfuric acid, nitric acid, etc.) can be added to these solvents. The amount of acid added is preferably 15 mol% or less relative to the solvent. By adding 15 mol% or less, the acid is less likely to remain in the copolymer, and is less likely to adversely affect the reaction during kneading and vulcanization of the composition. This washing step can suitably reduce the amount of catalyst residue in the copolymer.

[0063] (Other Components) The molded article may contain polymer components other than the copolymer having the conjugated diene units and non-conjugated olefin units described above, as well as other components such as various compounding agents. Examples of polymer components include resin components and rubber components. Examples of compounding agents include fillers, reinforcing fibers, antioxidants, softeners, crosslinking chemicals including stearic acid, zinc oxide, crosslinking accelerators and crosslinking agents, resins, ultraviolet absorbers, foaming agents, and colorants.

[0064] Furthermore, it is preferable that the molded article of this embodiment does not contain any components other than the copolymer described above. In other words, it is preferable that the molded article of this embodiment consists only of the copolymer. This is to suppress the deterioration of the copolymer's physical properties due to unnecessary chemical reactions and to improve its recyclability by not including any components other than the copolymer described above in the molded article.

[0065] The content of other components can be, for example, 10 parts by mass or less per 100 parts by mass of copolymer, and preferably 0 parts by mass.

[0066] The molded article of this embodiment may further contain a resin component as another component, in order to enhance various properties such as wear resistance and impact resistance. Examples of the resin component include olefin resins, polystyrene resins, polyvinyl chloride resins, polyurethane resins, polyamide resins, polyester resins, and the like.

[0067] -Olefin resin- The molded article may contain an olefin resin. Here, copolymers having the conjugated diene units and non-conjugated olefin units are excluded from the olefin resin. The inclusion of an olefin resin in the molded article can improve the wear resistance and impact resistance of the molded article.

[0068] The aforementioned olefin-based resin refers to a resin in which at least a polyolefin is crystalline and forms the main body of the resin. Examples include olefin-α-olefin copolymers, olefin copolymers, etc., which may be modified. Specifically, polyethylene, ethylene-propylene copolymer, ethylene-hexene copolymer, ethylene-pentene copolymer, ethylene-octene copolymer, propylene-1-hexene copolymer, ethylene-4-methyl-pentene copolymer, propylene-4-methyl-1-pentene copolymer, ethylene-butene copolymer, propylene-butene copolymer, 1-butene-hexene copolymer, 1-butene-4-methyl-pentene copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene Examples of polymers include butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer, propylene-methacrylic acid copolymer, propylene-methyl methacrylate copolymer, propylene-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer, propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer, and propylene-vinyl acetate copolymer.

[0069] The olefin resin preferably contains non-conjugated olefin units. The inclusion of non-conjugated olefin units in the olefin resin can improve the wear resistance of the molded article. The olefin resin preferably contains olefin units having 2 to 5 carbon atoms, and more preferably the difference between the number of carbon atoms in the non-conjugated olefin units contained in the copolymer and the number of carbon atoms in the non-conjugated olefin units contained in the olefin resin is 2 or less. The inclusion of non-conjugated olefin units, which are common units in the copolymer and the olefin resin, and the similar structure of the non-conjugated olefin units, further improves the mechanical strength of the molded article.

[0070] The difference between the number of carbon atoms in the non-conjugated olefin units contained in the copolymer and the number of carbon atoms in the non-conjugated olefin units contained in the olefin resin is more preferably 1 or less, and even more preferably 0. Furthermore, the number of carbon atoms in the olefin units is more preferably 2 to 4, and even more preferably 2 to 3, i.e., polyethylene resins and polypropylene resins are preferred.

[0071] The polyethylene resin refers to a polymer whose main chain contains ethylene units as the main component (for example, more than 50 mol%), and may also contain other units such as propylene units. Furthermore, the polyethylene resin may be thermosetting or thermoplastic. Specifically, examples include polyethylene (homopolymer), ethylene-propylene copolymer (however, with more than 50 mol% ethylene units), etc. In addition, polyethylene resins include types such as very low-density polyethylene (VLDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), and any of these may be used. Among these, from the viewpoint of high versatility, it is preferable to use one or more polyethylene resins selected from the group consisting of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE).

[0072] The aforementioned polypropylene resin refers to a polymer whose main chain contains propylene units as the main component (for example, more than 50 mol%), and may also contain other units such as ethylene units. Furthermore, the polypropylene resin may be thermosetting or thermoplastic. Specifically, examples include polypropylene (homopolymer), ethylene-propylene copolymer (however, with propylene units exceeding 50 mol%), etc.

[0073] From the viewpoint of improving the mechanical strength of the molded article, the olefin resin preferably has a number-average molecular weight (Mn) on a polystyrene basis of 5 to 10,000 kg / mol, more preferably 7 to 1,000 kg / mol, and even more preferably 10 to 1,000 kg / mol.

[0074] From the viewpoint of improving the mechanical strength of the molded article, the olefin resin preferably has a weight-average molecular weight (Mw) on a polystyrene basis of 100 to 300 kg / mol, more preferably 180 to 300 kg / mol, and even more preferably 200 to 280 kg / mol. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the olefin resin can be measured by gel permeation chromatography (GPC), and for example, a GPC (gel permeation chromatography) such as "HLC-8321GPC / HT" manufactured by Tosoh Corporation can be used.

[0075] -Polystyrene resins and styrene-based thermoplastic elastomers- The styrene-based thermoplastic elastomer has aromatic vinyl polymer blocks (hard segments) and rubber blocks (soft segments), where the aromatic vinyl polymer portion forms physical crosslinks and acts as crosslinking points, while the rubber blocks impart rubber elasticity. The polystyrene resins can be classified according to the arrangement of soft segments in the molecule, and examples include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), and moreover, block copolymers of crystalline polyethylene and ethylene / butylene-styrene random copolymer obtained by hydrogenating a block copolymer of polybutadiene and butadiene-styrene random copolymer, and diblock copolymers of crystalline polyethylene and polystyrene obtained by hydrogenating a block copolymer of polybutadiene or ethylene-butadiene random copolymer and polystyrene, for example. Among these, styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene / butylene-styrene block copolymer (SEBS), and styrene-ethylene / propylene-styrene block copolymer (SEPS) are preferred in terms of the balance of mechanical strength, heat stability, weather resistance, chemical resistance, gas barrier properties, flexibility, and processability.

[0076] -Polyvinyl Chloride Resins- The polyvinyl chloride resins are generally classified into the following three types: (Type 1) High molecular weight polyvinyl chloride (PVC) / plasticized polyvinyl chloride (PVC) blend type TPVC This is a thermoplastic elastomer in which high molecular weight PVC is used for the hard segment and plasticized PVC is used for the soft segment. By using high molecular weight PVC for the hard segment, crosslinking points are provided in the microcrystalline portion. (Type 2) Partially crosslinked PVC / plasticized PVC blend type TPVC This is a thermoplastic elastomer in which a partially crosslinked or branched structure of PVC is introduced for the hard segment and plasticized PVC is used for the soft segment. (Type 3) PVC / elastomer alloy type TPVC This is a thermoplastic elastomer in which PVC is used for the hard segment and rubber such as partially crosslinked nitrile butadiene rubber (NBR) or TPE such as polyurethane TPE or polyester TPE is used for the soft segment. The aforementioned chlorinated polyethylene resin is a flexible resin obtained by reacting polyethylene with chlorine gas in an aqueous suspension or a solvent such as carbon tetrachloride. Crystalline polyethylene blocks are used for the hard segments, and chlorinated polyethylene (CPE) blocks are used for the soft segments. In the CPE blocks, both polyethylene and chlorinated polyethylene components are present as a mixture in a multi-block or random structure.

[0077] -Polyurethane Resin- The polyurethane resin is a linear multiblock copolymer consisting of (1) polyurethane obtained by the reaction of a short-chain glycol and an isocyanate as a hard segment, and (2) polyurethane obtained by the reaction of a long-chain glycol and an isocyanate as a soft segment. Here, polyurethane is a general term for compounds having a urethane bond (-NHCOO-) obtained by a polyaddition reaction (urethane formation reaction) between an isocyanate (-NCO) and an alcohol (-OH). In the multilayer structure of the present invention, if the elastomer forming the elastomer layer is TPU, stretchability and thermoformability can be improved by laminating the elastomer layer. Furthermore, in such an inner liner, the interlayer adhesion between the elastomer layer and the barrier layer can be improved, resulting in high durability such as crack resistance, and gas barrier properties and stretchability can be maintained even when the inner liner is deformed during use.

[0078] -Polyamide Resin- The polyamide resin is a multiblock copolymer using polyamide as the hard segment and a low Tg polyether or polyester as the soft segment. The polyamide component constituting the hard segment is selected from nylon 6, nylon 66, nylon 610, nylon 11, nylon 12, etc., with nylon 6 and nylon 12 being the main components. Long-chain polyols such as polyether diols and polyester diols are used as constituent materials for the soft segment. Representative examples of polyether polyols include diol poly(oxytetramethylene) glycol (PTMG) and poly(oxypropylene) glycol, while representative examples of polyester polyols include poly(ethylene adipate) glycol and poly(butylene-1,4 adipate) glycol.

[0079] -Polyester Resin- The polyester resin is a multiblock copolymer in which polyester is used as the hard segment in the molecule and a polyether or polyester with a low glass transition temperature (Tg) as the soft segment.

[0080] -Rubber component- The molded article may contain a rubber component. Here, copolymers having the conjugated diene units and non-conjugated olefin units are excluded from the rubber component. The rubber component provides rubber elasticity to the molded article. Examples of the rubber component include diene rubbers such as natural rubber (NR) and synthetic diene rubber. Specific examples of synthetic diene rubbers include synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), halogenated butyl rubber, and acrylonylitol-butadiene rubber (NBR). The diene rubber may be used alone or in combination of two or more types. The diene rubber may also be modified. The rubber component may also contain non-diene rubber.

[0081] -Filler- The molded article may contain a filler. Including a filler in the molded article can improve the mechanical strength of the molded article. Examples of the filler include carbon black and inorganic fillers. The type of carbon black is not particularly limited, and examples include GPF, FEF, HAF, ISAF, SAF, etc., with HAF, ISAF, and SAF being preferred. Examples of the inorganic filler include metal oxides such as silica, alumina, and titania, with silica being preferred among these. The type of silica is not particularly limited, and examples include wet silica (hydrated silica), dry silica (anhydrous silica), colloidal silica, etc. Furthermore, when silica is included as a filler, the molded article may further contain a silane coupling agent to improve the dispersibility of silica in the layer containing the copolymer. Note that the carbon black and inorganic filler may be resources derived from sources other than petroleum. For example, recycled carbon black obtained by thermal decomposition of used rubber or silica derived from rice husks may be used.

[0082] The filler content is preferably 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of copolymer.

[0083] - Fatty Acids - The molded article may contain fatty acids. Examples of fatty acids include saturated fatty acids such as caprylic acid, pelargonic acid, capric acid, lauric acid, and myristic acid, and at least one unsaturated fatty acid such as oleic acid, linoleic acid, and vaccenic acid (each individually or as a mixture of two or more of these).

[0084] The fatty acid content is preferably 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of copolymer.

[0085] - Anti-aging agent - The molded article may contain an anti-aging agent. Examples of anti-aging agents include amine-ketone compounds, imidazole compounds, amine compounds, phenolic compounds, sulfur compounds, and phosphorus compounds.

[0086] -Softener- The molded article may contain a softener. Examples of softeners include petroleum-based softeners such as process oil, lubricating oil, naphthenic oil, paraffin, liquid paraffin, petroleum asphalt, and petrolatum; fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil, and coconut oil; and waxes such as beeswax, carnauba wax, and lanolin. These softeners may be used individually or in combination of two or more. The softener may also be derived from resources other than petroleum. For example, recycled oil obtained by thermally decomposing used rubber may be used.

[0087] -Crosslinking Chemicals- The molded article may contain crosslinking chemicals. In this specification, crosslinking chemicals include crosslinking agents and crosslinking accelerators. The molded article may contain crosslinking chemicals, but preferably does not. It is believed that the absence of crosslinking chemicals in the molded article can suppress the decrease in stress and elongation. In particular, it is preferable that the molded article of this embodiment does not contain peroxides and sulfur.

[0088] The crosslinking agent content is preferably 1 part by mass or less per 100 parts by mass of copolymer. When a crosslinking agent is included, it is believed that the reduction in elongation and stress can be suppressed by keeping the crosslinking agent content below the above upper limit. From a similar viewpoint, the crosslinking agent content is more preferably 0.5 parts by mass or less per 100 parts by mass of copolymer, and it is particularly preferable that there is 0 parts by mass, i.e., no crosslinking agent is included.

[0089] --Crosslinking Agent-- There are no particular restrictions on the crosslinking agent, and commonly used examples include peroxides, sulfur, oximes, amines, and ultraviolet curing agents. Since the copolymer contains conjugated diene units, it can be crosslinked (vulcanized) with sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur.

[0090] --Crosslinking accelerators-- Examples of crosslinking accelerators (vulcanization accelerators) include guazinine-based, sulfenamide-based, thiuram-based, thiazole-based, aldehydeamine-based, and thiocarbamate-based crosslinking accelerators.

[0091] (Electron Beam Crosslinking) The molded article of this embodiment is subjected to electron beam crosslinking. In other words, the molded article of this embodiment has an electron beam crosslinked structure (a crosslinked structure by an electron beam). To put it another way, the molded article of this embodiment is an electron beam crosslinked article. The molded article of this embodiment has a crosslinked structure formed by electron beam irradiation, and compared to the case of sulfur crosslinking or peroxide crosslinking, there is no need to add crosslinking agents such as sulfur or peroxide, so the number of work steps can be reduced and workability is excellent. Furthermore, as mentioned above, there is no need to add crosslinking agents to the copolymer, so it can be expected that the physical properties will not deteriorate due to the inclusion of crosslinking agents.

[0092] For electron beam irradiation used for electron beam crosslinking, the acceleration voltage is preferably 100 kV to 3000 kV. This is preferable for uniformity of crosslinking and reduction of sample damage. From the viewpoint of uniformity in the thickness direction of the crosslinking, the acceleration voltage is more preferably 300 kV or higher, and even more preferably 500 kV or higher. Also, from the viewpoint of sample damage, the acceleration voltage is more preferably 2000 kV or lower, and even more preferably 1000 kV or lower.

[0093] Furthermore, the electron beam irradiation dose for electron beam crosslinking is preferably greater than 0 kGy and less than or equal to 500 kGy. This is preferable because it improves the fracture characteristics. From the viewpoint of improving fracture characteristics through crosslinking, the acceleration voltage is more preferably 20 kGy or more, and even more preferably 50 kGy or more. Also, from the viewpoint of suppressing over-crosslinking and molecular chain severance, the acceleration voltage is more preferably 300 kGy or less, and even more preferably 150 kGy or less.

[0094] The method for performing electron beam crosslinking is not particularly limited and can be carried out using known methods with an electron beam irradiation device.

[0095] [Method for Manufacturing Molded Articles] The molded articles of this embodiment may be manufactured using the copolymer having the conjugated diene units and non-conjugated olefin units as is, or by mixing the copolymer with any other additive components. Preferably, the copolymer is used as is. Alternatively, the copolymer may be kneaded alone or together with other optional additive components using a kneader such as a single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, or internal mixer. The kneading of each component may be carried out in one stage or in two or more stages. When the molded articles of this embodiment are formed from a composition containing the copolymer and other optional additive components, the composition may contain, in addition to the copolymer, the above-mentioned olefin resin, rubber component, filler, silane coupling agent, antioxidant, softener, crosslinking agent, crosslinking accelerator, etc. Here, the content of the copolymer in the composition is not particularly limited, but it is preferably 50% by mass or more, preferably 70% by mass or more, and preferably 90% by mass or more.

[0096] When the components of the composition are melt-kneaded in an extruder and the composition is extruded, the extruded composition may be directly cut into pellets, or strands may be formed and then the strands cut into pellets in a pelletizer. The shape of the pellets can be general shapes such as cylinders, prisms, and spheres.

[0097] The molded article may be manufactured by melting and kneading the composition and then using various methods such as extrusion or hot pressing.

[0098] The following describes a preferred method for manufacturing a molded article according to this embodiment. The preferred method for manufacturing a molded article according to this embodiment includes the steps of (1) molding a kneaded copolymer to produce a molded article, and (2) irradiating the molded article with an electron beam to perform electron beam crosslinking. If the molded article contains other components in addition to the copolymer, the method may include a step of kneading the copolymer and the other components before step (1).

[0099] -Step (1)- In Step (1), the molded body can be manufactured by, for example, extrusion, hot pressing, injection molding, etc. The conditions for manufacturing the molded body are not particularly limited and can be various, but for example, it can be done at a temperature of 100 to 250°C.

[0100] -Step (2)- By step (2) of applying electron beam crosslinking, electron beam crosslinking can be imparted to the molded body. By applying electron beam crosslinking to the molded body, the molded body becomes superior in durability, self-healing properties, and shape recovery compared to the case without crosslinking.

[0101] The electron beam irradiation for electron beam crosslinking can be performed using an electron beam irradiation device in a known manner.

[0102] In step (2), the electron beam irradiation for electron beam crosslinking is preferably performed at an acceleration voltage of 100 kV or more and 3000 kV or less. This is preferable for uniformity of crosslinking and reduction of sample damage. From the viewpoint of uniformity of the crosslinking in the thickness direction, the acceleration voltage is more preferably 300 kV or more, and even more preferably 500 kV or more. Also, from the viewpoint of sample damage, the acceleration voltage is more preferably 2000 kV or less, and even more preferably 1000 kV or less.

[0103] Furthermore, in step (2), the electron beam irradiation dose for electron beam crosslinking is preferably greater than 0 kGy and less than or equal to 500 kGy. This is preferable due to the destructive properties. From the viewpoint of improving destructive properties through crosslinking, the acceleration voltage is more preferably 20 kGy or more, and even more preferably 50 kGy or more. Furthermore, from the viewpoint of suppressing over-crosslinking and molecular chain severance, the acceleration voltage is more preferably 300 kGy or less, and even more preferably 150 kGy or less.

[0104] (Applications of Molded Articles) The molded articles of this embodiment are excellent in durability, shape recovery, and self-healing properties, and can be used in products for various applications, such as rubber products and resin products. More specifically, the molded articles of this embodiment are suitable for tires and automobile parts (automobile seats, automobile batteries (lithium-ion batteries, etc.), weatherstrips, hose tubes, cables, sealing materials, etc.), ship parts, building materials, etc. In addition, the molded articles of this embodiment are suitable for crawlers, hoses, resin piping, sound-absorbing materials, bedding, precision parts for office equipment (OA rollers), bicycle frames, golf balls, tennis rackets, golf shafts, resin additives, filters, adhesives, sealants, inks, medical devices (medical tubes, bags, microneedles, rubber sleeves, artificial organs, caps, packings, syringe gaskets, drug stoppers, prosthetics, artificial limbs), cosmetics (UV powder, puffs, containers, wax, shampoo, conditioner), detergents, and building materials (flooring materials, vibration damping rubber, seismic isolation rubber, building films). It is suitable for use in sound-absorbing materials, waterproof sheets, heat-insulating materials, joint fillers, sealants, packaging materials, liquid crystal materials, organic EL materials, organic semiconductor materials, electronic materials, electronic devices, communication equipment, aircraft parts, machine parts, electronic components, agricultural materials, electric wires, cables, fibers (wearable substrates), daily necessities (toothbrushes, shoe soles, eyeglasses, lures, binoculars, toys, dust masks, garden hoses), robot parts, optical components, road materials (asphalt, guardrails, poles, signs), protective equipment (shoes, puncture-resistant safety shoes, bulletproof vests), electrical equipment exterior parts, OA exterior parts, soles, sealants, etc. In the above, OA stands for office automation, UV stands for ultraviolet, and EL stands for electro-luminescence.

[0105] <Rubber Products> The rubber products of this embodiment are characterized by using the molded body described above. In other words, the rubber products of this embodiment are characterized by comprising the molded body described above. Because the rubber products use the molded body described above, they have excellent durability, shape recovery, and self-healing properties.

[0106] Suitable rubber products include those listed in the section on (Applications of molded products).

[0107] <Resin Product> The resin product of this embodiment is characterized by using the above-described molded body. In other words, the resin product according to this embodiment is characterized by including the above-described molded body. Since the resin product uses the above-described molded body, it is excellent in durability, shape recovery property, and self-healing property.

[0108] As the resin product, for example, those described in the section of (Use of the Molded Body) are preferably cited.

[0109] Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples at all.

[0110] <Synthesis of Copolymer> (Synthesis of Copolymer 1) 75 g of styrene and 675 g of toluene were added into a sufficiently dried 2000 mL pressure-resistant stainless steel reactor. On the other hand, in a glove box under a nitrogen atmosphere, in a glass container, {((1-benzyldimethylsilyl-3-methyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex { (1-BnMe ２ Si-3-Me]C ９ H ５ Gd[N(SiHMe ２ ) ２ ２} of 0.075 mmol and dimethylanilinium tetrakis(pentafluorophenyl)borate [Me ２ NHPhB(C ６ F ５ ) ４0.083 mmol of [amount] and 0.35 mmol of diisobutylaluminum hydride were added, and then 30 g of toluene was added to prepare the catalyst solution. The obtained catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 60°C. Next, ethylene was added to the pressure-resistant stainless steel reactor at a pressure of 1.5 MPa, and copolymerization was carried out at 75°C for a total of 3 hours. During copolymerization, 80 g of toluene solution containing 20 g of 1,3-butadiene was continuously added at a rate of 0.4 to 0.6 mL / min. Next, 1 mL of isopropanol solution containing 5% by mass of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) was added to the pressure-resistant stainless steel reactor to stop the reaction. Then, the copolymer was separated using a large amount of methanol and vacuum-dried at 50°C to obtain copolymer 1.

[0111] (Synthesis of Copolymer 2) In a thoroughly dried 2000 mL pressure-resistant stainless steel reactor, 30 g of styrene, 20 g of toluene solution containing 5 g of 1,3-butadiene, and 430 g of toluene were added. Meanwhile, in a glove box under a nitrogen atmosphere, mono(1,3-bis(tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1,3-[(t-Bu)Me ２ Si] ２ C ９ H ５ Gd[N(SiHMe ２ ) ２ ] ２} 0.075 mmol, dimethylanilinium tetrakis(pentafluorophenyl) borate [Me ２ NHPhB(C) ６ F ５ ) ４0.075 mmol of [amount] and 0.35 mmol of diisobutylaluminum hydride were added, and then 20 mL of toluene was added to prepare the catalyst solution. The obtained catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 60°C. Next, ethylene was added to the pressure-resistant stainless steel reactor at a pressure of 1.0 MPa, and copolymerization was carried out at 75°C for a total of 3 hours. During copolymerization, 120 g of a toluene solution containing 30 g of 1,3-butadiene was continuously added at a rate of 2.5 to 2.8 mL / min. Next, 1 mL of an isopropanol solution containing 5% by mass of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) was added to the pressure-resistant stainless steel reactor to stop the reaction. Then, the copolymer was separated using a large amount of methanol and vacuum-dried at 50°C to obtain copolymer 2.

[0112] (Synthesis of Copolymer 3) In a thoroughly dried 2000 mL pressure-resistant stainless steel reactor, 30 g of styrene, 20 g of toluene solution containing 5 g of 1,3-butadiene, and 430 g of toluene were added. Meanwhile, in a glove box under a nitrogen atmosphere, mono(1,3-bis(tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1,3-[(t-Bu)Me ２ Si] ２ C ９ H ５ Gd[N(SiHMe ２ ) ２ ] ２} 0.075 mmol, dimethylanilinium tetrakis(pentafluorophenyl) borate [Me ２ NHPhB(C) ６ F ５ ) ４0.075 mmol of [amount] and 0.35 mmol of diisobutylaluminum hydride were added, and then 20 mL of toluene was added to prepare the catalyst solution. The obtained catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 60°C. Next, ethylene was added to the pressure-resistant stainless steel reactor at a pressure of 1.0 MPa, and copolymerization was carried out at 75°C for a total of 3 hours. During copolymerization, 240 g of a toluene solution containing 60 g of 1,3-butadiene was continuously added at a rate of 2.5 to 2.8 mL / min. Next, 1 mL of an isopropanol solution containing 5% by mass of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) was added to the pressure-resistant stainless steel reactor to stop the reaction. Then, the copolymer was separated using a large amount of methanol and vacuum-dried at 50°C to obtain copolymer 3.

[0113] (Synthesis of Copolymer 4) In a thoroughly dried 2000 mL pressure-resistant stainless steel reactor, 30 g of styrene, 20 g of toluene solution containing 5 g of 1,3-butadiene, and 430 g of toluene were added. Meanwhile, in a glove box under a nitrogen atmosphere, mono(1,3-bis(tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1,3-[(t-Bu)Me ２ Si] ２ C ９ H ５ Gd[N(SiHMe ２ ) ２ ] ２} 0.075 mmol, dimethylanilinium tetrakis(pentafluorophenyl) borate [Me ２ NHPhB(C) ６ F ５ ) ４0.075 mmol of [amount] and 0.35 mmol of diisobutylaluminum hydride were added, and then 20 mL of toluene was added to prepare the catalyst solution. The obtained catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 60°C. Next, ethylene was added to the pressure-resistant stainless steel reactor at a pressure of 1.0 MPa, and copolymerization was carried out at 75°C for a total of 3 hours. During copolymerization, 350 g of a toluene solution containing 90 g of 1,3-butadiene was continuously added at a rate of 2.5 to 2.8 mL / min. Next, 1 mL of an isopropanol solution containing 5% by mass of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) was added to the pressure-resistant stainless steel reactor to stop the reaction. Then, the copolymer was separated using a large amount of methanol and vacuum-dried at 50°C to obtain copolymer 4.

[0114] <Method for measuring the physical properties of the copolymer> The following physical properties were measured for the synthesized copolymer. The measurement results are shown in Table 1.

[0115] (1) Number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) Gel permeation chromatography [GPC: HLC-8321GPC / HT manufactured by Tosoh Corporation, Column: GMH manufactured by Tosoh Corporation] ＨＲ Using two H(S)HT tubes and a differential refractometer (RI) detector, the number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) of the copolymer were determined in polystyrene equivalent, with monodisperse polystyrene as the reference. The measurement temperature was 140°C.

[0116] (2) Content of butadiene units, ethylene units, and styrene units The content (mol%) of ethylene units, butadiene units, and styrene units in the copolymer is １ The integral ratio of each peak in the 1H-NMR spectrum (100°C, d-tetrachloroethane standard: 6 ppm) was used to determine the integral ratio.

[0117] (3) Melting point (Tm) The melting point (Tm) of the copolymer was measured using a differential scanning calorimeter (DSC, manufactured by T.A. Instruments Japan, "DSCQ2000") in accordance with JIS K 7121-1987.

[0118] (4) Tensile strength (Tb) and elongation at break (Eb) The specimens were formed into a dumbbell shape No. 3 according to JIS K 6251 (2017) and used as test specimens. Tensile strength (Tb) was measured according to JIS K 6251 (2017) using a tensile testing device (manufactured by Instron), by stretching the specimen to 100% at 25°C and measuring the maximum tensile force required to break the specimen. Elongation at break (Eb) was measured by stretching the specimen at a speed of 100 mm / min at 25°C and measuring the length at which the specimen broke, and was determined as the length relative to the length before stretching (100%).

[0119] (5) Confirmation of main chain structure For copolymers 1 to 4, based on the method described in paragraph

[0046] , １３ By measuring the C-NMR spectrum, １３ Since no peaks were observed in the 10–24 ppm range in the C-NMR spectral chart, it was confirmed that the main chain of all samples has an acyclic structure.

[0120]

[0121] <Preparation of molded bodies> Each of the above copolymers was heated at 180°C for 3 minutes using a hot press to produce molded bodies.

[0122] <Conditions for Crosslinking> When crosslinking was applied to the molded body, the following conditions were used for each type of crosslinking. (Electron beam crosslinking) Electron beam irradiation was performed under the following conditions to perform electron beam crosslinking. Acceleration voltage: 500 kV Dosage: 25 kGy / cycle Equipment: EPS-750 kV (manufactured by NHV Corporation)

[0123] (Sulfur Crosslinking) A polymer composition was obtained by kneading the molded body, sulfur, vulcanization accelerator, and vulcanization accelerator auxiliary at a temperature of 110°C using a mixer, and then heating it in a hot press at 180°C for 25 minutes to perform sulfur crosslinking.

[0124] (Peroxide Crosslinking) The molded body and peroxide were kneaded together using a mixer at a temperature of 110°C to obtain a polymer composition, and then peroxide crosslinking was performed by heating with a hot press at 180°C for 10 minutes.

[0125] <Evaluation of molded articles> (1) Stress and elongation Six samples were prepared using copolymer 3 synthesized by the method described above.・Uncrosslinked sample (indicated as "Uncrosslinked" in Figure 1) ・Sulfur-crosslinked sample 1 (sulfur content: 1.5 parts by mass per 100 parts by mass of copolymer) (indicated as "Sulfur-crosslinked" in Figure 1) ・Sulfur-crosslinked sample 2 (less sulfur added than sulfur-crosslinked sample 1, sulfur content: 1 part by mass per 100 parts by mass of copolymer) (indicated as "Sulfur-crosslinked (reduced sulfur content)" in Figure 1) ・Peroxide-crosslinked sample 1 (peroxide content: 1 part by mass per 100 parts by mass of copolymer) (indicated as "Peroxide-crosslinked" in Figure 1) ・Peroxide-crosslinked sample 2 (less peroxide added than peroxide-crosslinked sample 1, peroxide content: 0.5 parts by mass per 100 parts by mass of copolymer) (indicated as "Peroxide-crosslinked (reduced peroxide content)" in Figure 1) ・Electron beam-crosslinked sample (indicated as "Electron beam-crosslinked" in Figure 1) Tensile tests were performed on each of the above-prepared samples, and stress and elongation were measured. The measurement conditions were as follows. Shape: Outer diameter φ12 mm, inner diameter Φ8 mm Test speed: 100 mm / min Measuring device: Universal material tester Model 5566 (manufactured by Instron) The evaluation results are shown in Figure 1.

[0126] (2) Abrasion resistance was evaluated as one of the indicators of abrasion resistance durability. Measurements were taken for molded articles containing each of the above copolymers in accordance with JIS-K 6264-2, and the abrasion mass was used as an indicator of abrasion resistance. The measurement conditions were as follows: (Conditions) Load: 9.8 N Rotation speed: 1000 rpm (rotation speed: 60 rpm) Measurement device: Rotary abrasion tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) A higher value indicates better abrasion resistance. The evaluation results are shown in Table 2. The evaluation was performed for each molded article using the same copolymer, and the results are expressed as an index with the uncrosslinked case set to 100. For example, Example 1-1 is expressed as an index with Comparative Example 1-1 set to 100, and Example 1-3 is expressed as an index with Comparative Example 1-2 set to 100.

[0127] (3) As one of the indicators of puncture resistance durability, puncture resistance was evaluated. For molded articles containing each of the above copolymers, measurements were taken in accordance with JIS-Z 1707, and the load applied when the material was penetrated was determined. The measurement conditions were as follows: (Conditions) Sample: Film thickness 1.0 mm Needle: Diameter 1.0 mm, tip shape radius 0.5 mm Test speed: 50 mm / min Measuring device: Universal material tester 5566 (Instron Co., Ltd.) The larger the numerical value of the load at penetration and the deformation at penetration, the better the puncture resistance. It is preferable that the deformation at penetration is 85 or higher. The evaluation results are shown in Table 2. The evaluation was performed for each molded article using the same copolymer, and is expressed as an index with the uncrosslinked case set to 100. For example, Example 1-1 is expressed as an index with Comparative Example 1-1 set to 100, and Example 1-3 is expressed as an index with Comparative Example 1-2 set to 100.

[0128] (4) Shape recovery The shape recovery at each temperature was measured according to the following procedures (i) to (v). (i) A pancake-shaped sample with a diameter of Φ8 mm and a thickness of 2 mm was pressed to a thickness of 1 mm at 120°C and cooled to 25°C while compressed. (ii) The sample was removed from the press and its diameter was measured. The degree of shape recovery (%) was calculated as measured value / 8 × 100. (iii) The sample was placed in a 60°C oven, and after 5 minutes, it was removed and the degree of shape recovery was measured. (iv) The sample was again placed in a 70°C oven, and after 5 minutes, it was removed and the degree of shape recovery was measured. (v) The temperature in (iv) was increased by 10°C increments, and (iv) was repeated up to 120°C. The results are shown in Table 3. The closer to 100%, the better the shape recovery.

[0129] (5) After scratching the self-healing molded body, it was heated, and the self-healing properties of the molded body were evaluated by visually observing the scratches. The evaluation method and evaluation results are as follows. Molded body A, which was molded using only copolymer 1, and molded body B, which was made using copolymer 1 and 5 parts by mass of carbon black (manufactured by Asahi Carbon Co., Ltd., trade name "N234") per 100 parts by mass of copolymer 1 were used. Two molded bodies A and two molded bodies B were used, and two were prepared: one that was irradiated with an electron beam to undergo electron beam crosslinking, and one that was not irradiated with an electron beam to undergo electron beam crosslinking. The molded bodies that were not subjected to electron beam crosslinking were designated as molded body A-1 and molded body B-1, respectively, and the molded bodies that were subjected to electron beam crosslinking were designated as molded body A-2 and molded body B-2, respectively. Scratches were made in these molded bodies, and after heating at 100°C for 30 minutes, the condition of the scratches was visually observed and evaluated. The evaluation results showed that molded bodies A-1 and B-1 clearly had defects when observed visually, while molded bodies A-2 and B-2 had almost no defects when observed visually. In other words, molded bodies A-2 and B-2, which were subjected to electron beam crosslinking, exhibited superior self-healing properties compared to the uncrosslinked cases.

[0130]

[0131]

[0132] Table 2 shows that the material treated with electron beam crosslinking exhibits superior durability compared to the material not treated with electron beam irradiation, i.e., the material not treated with electron beam crosslinking.

[0133] Table 3 shows that the shape recovery is superior when electron beam crosslinking is applied compared to when electron beam irradiation is not performed, i.e., when electron beam crosslinking is not applied.

[0134] Therefore, as can be seen from Tables 2 and 3, molded articles containing copolymers and subjected to electron beam crosslinking exhibit superior durability and shape recovery. Furthermore, the evaluation results in (5) above show that they also exhibit excellent self-healing properties. Moreover, as shown in Figure 1, it can be seen that the molded articles subjected to electron beam crosslinking maintain the same elongation and stress as the uncrosslinked molded articles.

[0135] According to this disclosure, it is possible to provide a molded article with improved durability, shape recovery, and self-healing properties while maintaining elongation and stress at the same level as in the case of an uncrosslinked product.

Claims

1. A molded article comprising a copolymer having conjugated diene units and non-conjugated olefin units, which has been subjected to electron beam crosslinking.

2. The molded article according to claim 1, wherein the copolymer has a melting point of 50 to 120°C.

3. The molded article according to claim 1, wherein the copolymer has a content of conjugated diene units that is greater than 0 mol% and less than or equal to 50 mol%, and a content of unconjugated olefin units that is 50 mol% or more and less than 100 mol%.

4. The molded article according to claim 1, wherein the copolymer further comprises aromatic vinyl units.

5. The molded article according to claim 1, wherein the dose of electron beam irradiation for electron beam crosslinking is greater than 0 kGy and less than or equal to 500 kGy.

6. The molded article according to claim 1, wherein the content of the crosslinking agent is 1 part by mass or less per 100 parts by mass of the copolymer.

7. The molded article according to claim 1, further comprising a fatty acid and a filler.

8. A rubber product using the molded body described in claim 1.

9. A resin product using the molded article described in claim 1.

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