Laminate, method for manufacturing a laminate, and tire

Abstract

To provide a laminate having high delamination strength and high productivity.SOLUTION: A laminate 1 includes at least two rubber layers. One rubber layer (A) 2 and another rubber layer (B) 3 adjacent to the rubber layer (A) 2 in the laminate 1 each contain: a rubber component containing 50 mass% or more of a diene rubber; and a copolymer having a conjugated diene unit and a non-conjugated olefin unit. The content of the copolymer is 3-40 pts.mass based on 100 pts.mass of the rubber component.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate, a method for producing a laminate, and a tire. [Background Art]

[0002] Conventionally, tires have been repaired by attaching a repair patch made of unvulcanized rubber to the damaged portion of a damaged tire, heating the patch at a high temperature to fix it to the damaged portion, thereby repairing the tire. Further, when the tread rubber of a tire is worn, it is generally practiced to physically grind off the worn tread rubber (a so-called buffing process) to obtain a base tire, and then bond a precured tread (a pre-vulcanized tread rubber member) to the base tire to retread the tire. As described above, bonding vulcanized rubber to unvulcanized rubber or bonding vulcanized rubbers to each other is widely performed, and there is a demand for a technique for improving the adhesiveness (peel strength) between rubber layers.

[0003] For example, Patent Document 1 below discloses a method for bonding vulcanized rubber and unvulcanized rubber, which comprises, in bonding vulcanized rubber and unvulcanized rubber, subjecting the bonded portion on the vulcanized rubber side to plasma treatment, and then vulcanizing and bonding the vulcanized rubber and the unvulcanized rubber. Further, Patent Document 2 below discloses that a pretreatment such as buffing is performed on the adhesion surface of a precured tread to a base tire. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Laid-Open No. 2007-217559 [Patent Document 2] Japanese Patent Laid-Open No. 5-116235 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] As described above, conventional methods have involved various pretreatments to improve the adhesion (peel strength) between rubber layers. However, these pretreatments are time-consuming, and improvements are needed from a productivity standpoint.

[0006] Therefore, the present invention aims to solve the problems of the above-mentioned prior art and provide a laminate with high interlayer peel strength and high productivity. Furthermore, the present invention aims to provide a method for manufacturing such a laminate, and a tire comprising such a laminate that is highly durable and highly productive. [Means for solving the problem]

[0007] The essential structure of the laminate, method for manufacturing the laminate, and tire of the present invention, which solves the above problems, is as follows.

[0008] [1] A laminate comprising at least two rubber layers, A laminate characterized in that one rubber layer (A) and another rubber layer (B) adjacent to the rubber layer (A) each contain a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the content of the copolymer is 3 to 40 parts by mass per 100 parts by mass of the rubber component. The laminate of the present invention described above [1] has high interlayer peel strength and high productivity.

[0009] [2] The laminate according to [1], wherein the copolymer has a melting point of 50 to 120°C. In the laminate described in [2] above, the crack resistance of the rubber layer (A) and the rubber layer (B) is high, and the workability in manufacturing the rubber layer (A) and the rubber layer (B) is improved.

[0010] [3] The laminate 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%. According to the laminate described in [3] above, the high-temperature fracture characteristics of the rubber layer (A) and rubber layer (B) can be effectively improved.

[0011] [4] The laminate according to any one of [1] to [3], wherein the copolymer further comprises aromatic vinyl units. In the laminate described in [4] above, the crack resistance of the rubber layer (A) and the rubber layer (B) is improved.

[0012] [5] The laminate according to [4], wherein the copolymer has a content of 1 to 50 mol% of the conjugated diene units, a content of 40 to 97 mol% of the unconjugated olefin units, and a content of 2 to 35 mol% of the aromatic vinyl units. According to the laminate described in [5] above, the flexibility and mechanical strength of the rubber layer (A) and rubber layer (B) can be improved while also improving the peel strength between the rubber layer (A) and the rubber layer (B).

[0013] [6] The laminate according to any one of [1] to [5], wherein the copolymer has a degree of crystallinity of 0.5 to 50%. According to the laminate described in [6] above, the mechanical strength of the rubber layer (A) and the rubber layer (B) can be improved.

[0014] [7] The laminate according to any one of [1] to [6], wherein the difference between the melting point of the copolymer contained in the rubber layer (A) and the melting point of the copolymer contained in the rubber layer (B) is 30°C or less. The laminate described in [7] above has further improved peel strength between rubber layer (A) and rubber layer (B).

[0015] [8] A method for producing a laminate, characterized by laminating at least two crosslinked rubber layers, each containing a rubber component comprising 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component, and heating the laminate. According to the method for producing a laminate described in [8] above, a laminate having high interlayer peel strength can be obtained with high productivity.

[0016] [9] A method for producing a laminate, comprising: laminating at least one crosslinked rubber layer and at least one uncrosslinked rubber layer, followed by heating, wherein the at least one crosslinked rubber layer comprises a rubber component containing 50% by mass or more of a diene rubber and a copolymer having a conjugated diene unit and a non-conjugated olefin unit, and the content of the copolymer is 3 to 40 parts by mass based on 100 parts by mass of the rubber component; and the at least one uncrosslinked rubber layer comprises a rubber component containing 50% by mass or more of a diene rubber and a copolymer having a conjugated diene unit and a non-conjugated olefin unit, and the content of the copolymer is 3 to 40 parts by mass based on 100 parts by mass of the rubber component. According to the method for producing a laminate described in [9] above, a laminate having high interlayer peel strength can be obtained with high productivity.

[0017]

[10] A method for producing a laminate, comprising laminating at least two uncrosslinked rubber layers, followed by heating, wherein the uncrosslinked rubber layers each comprise a rubber component containing 50% by mass or more of a diene rubber and a copolymer having a conjugated diene unit and a non-conjugated olefin unit, and the content of the copolymer is 3 to 40 parts by mass based on 100 parts by mass of the rubber component. According to the method for producing a laminate described in

[10] above, a laminate having high interlayer peel strength can be obtained with high productivity.

[0018]

[11] A tire comprising the laminate according to any one of [1] to [7]. The tire of the present invention described in

[11] above has high durability and high productivity. Effects of the Invention

[0019] According to the present invention, a laminate having high interlayer peel strength and high productivity can be provided. Further, according to the present invention, a method for producing such a laminate, and a tire including such a laminate and having high durability and high productivity can be provided. Brief Description of the Drawings

[0020] [Figure 1] This is a schematic cross-sectional view in the thickness direction showing the laminate of this embodiment. [Modes for carrying out the invention]

[0021] The laminate, method for manufacturing the laminate, and tire of the present invention will be described in detail below based on embodiments thereof.

[0022] <Definition> 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.

[0023] In this specification, copolymers having conjugated diene units and non-conjugated olefin units are distinguished from rubber components; that is, "copolymers having conjugated diene units and non-conjugated olefin units" are excluded from "rubber components."

[0024] <Laminate> The laminate of this embodiment is a laminate comprising at least two rubber layers. In the laminate of this embodiment, one rubber layer (A) and another rubber layer (B) adjacent to rubber layer (A) each contain a rubber component comprising 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units (hereinafter sometimes simply referred to as "polymer"), wherein the content of the copolymer is 3 to 40 parts by mass per 100 parts by mass of the rubber component.

[0025] In the laminate of this embodiment, both adjacent rubber layers (A) and rubber layer (B) each contain 3 to 40 parts by mass of a copolymer having conjugated diene units and non-conjugated olefin units per 100 parts by mass of a rubber component containing 50% by mass or more of diene rubber. Since this copolymer can be melted by heating, for example, and bonded with high adhesive strength, the peel strength between rubber layer (A) and rubber layer (B) is high. Furthermore, since the copolymer having the conjugated diene units and the non-conjugated olefin units melts upon heating, for example, the rubber layers (A) and / or (B) can be easily joined by laminating the rubber layers (A) and (B) and heating them, without requiring any pretreatment of the rubber layers (A) and / or (B). Therefore, the laminate of this embodiment has high peel strength between the rubber layer (A) and the rubber layer (B), as well as high productivity.

[0026] The laminate of this embodiment includes at least two rubber layers, but the thickness of each rubber layer is not particularly limited, for example, 1 mm or more. Furthermore, there is no particular upper limit, for example, 2000 mm or less. In the laminate of this embodiment, one rubber layer (A) and another rubber layer (B) adjacent to rubber layer (A) each contain a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units. It is sufficient that adjacent rubber layers (A) and rubber layers (B) in the laminate contain a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units. If the laminate consists of three or more layers, the composition of the other layers is not particularly limited and may be the same as or different from the composition of rubber layer (A) and / or rubber layer (B).

[0027] (Rubber component) The rubber layer (A) and rubber layer (B) contain a rubber component comprising 50% by mass or more of diene rubber. As described above, 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 rubber layer (A) and rubber layer (B). Examples of the diene rubber include natural rubber (NR) and synthetic diene rubber. Specific examples of synthetic diene rubber 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 individually or in combination of two or more types. The diene rubber may also be modified. The rubber component may include a non-diene rubber in addition to the diene rubber. Here, the proportion of the diene rubber in the rubber component is 50% by mass or more, and may be 100% by mass. When the proportion of the diene rubber in the rubber component is 50% by mass or more, the rubber layer (A) and the rubber layer (B) will have sufficient rubber elasticity.

[0028] (Copolymer having conjugated diene units and non-conjugated olefin units) The copolymer having the conjugated diene unit and the non-conjugated olefin unit may be a binary copolymer consisting of two units, the conjugated diene unit and the non-conjugated olefin unit; it may also be a ternary copolymer consisting of three units, including an aromatic vinyl unit; or it may also be a polypolymer containing other monomer units.

[0029] The rubber layer (A) and rubber layer (B) are characterized in that the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component (in other words, the rubber component excluding the copolymer). If the copolymer content is 3 parts by mass or more per 100 parts by mass of the rubber component, the peel strength between rubber layer (A) and rubber layer (B) and the mechanical strength of rubber layer (A) and rubber layer (B) are improved, and if it is 40 parts by mass or less, the flexibility of rubber layer (A) and rubber layer (B) is improved.

[0030] Preferably, the difference between the copolymer content in rubber layer (A) and the copolymer content in rubber layer (B) per 100 parts by mass of the rubber component is 20 parts by mass or less. When the difference in copolymer content between rubber layer (A) and rubber layer (B) is 20 parts by mass or less, the physical properties of rubber layer (A) and rubber layer (B) tend to become similar, making it easier to improve the peel strength between rubber layer (A) and rubber layer (B). Furthermore, from the viewpoint of peel strength between rubber layer (A) and rubber layer (B), it is even more preferable that the copolymer content in rubber layer (A) and the copolymer content in rubber layer (B) are equal.

[0031] -Conjugated diene units- The aforementioned conjugated diene unit is a constituent unit derived from a conjugated diene compound as a monomer. Here, the term "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, and 2,3-dimethyl-1,3-butadiene. The conjugated diene compound may be used alone or in combination of two or more types.

[0032] 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, from the viewpoint of improving the mechanical strength of the rubber layer (A) and rubber layer (B). In other words, the conjugated diene units in the copolymer preferably include at least one selected from the group consisting of 1,3-butadiene units and isoprene units, more preferably consist only of at least one selected from the group consisting of 1,3-butadiene units and isoprene units, and even more preferably consist only of 1,3-butadiene units.

[0033] When the copolymer is a binary copolymer, the content of conjugated diene units is preferably greater than 0 mol% and less than or equal to 50 mol%. In this case, a copolymer with excellent elongation and weather resistance can be obtained. From a similar viewpoint, it is more preferable that the proportion of conjugated diene units in the binary copolymer is 40 mol% or less.

[0034] 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. Similarly, 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, this proportion has the same meaning as the amount of 1,2-vinyl bonds.

[0035] 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 30 mol% or less. By having a conjugated diene unit content of 1 to 50 mol% of the total copolymer, the flexibility and mechanical strength of the rubber layer (A) and rubber layer (B) can be improved. From the viewpoint of further improving the flexibility and mechanical strength of the rubber layer (A) and rubber layer (B), the content of conjugated diene units is preferably in the range of 1 to 50 mol%, more preferably in the range of 3 to 40 mol%, and even more preferably in the range of 5 to 30 mol% of the total copolymer.

[0036] - Non-conjugated olefin units - The aforementioned 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 compound having one or more carbon-carbon double bonds. Preferably, the non-conjugated olefin compound 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 used alone or in combination of two or more types.

[0037] The non-conjugated olefin compound used as the monomer of the copolymer is preferably an acyclic non-conjugated olefin compound, from the viewpoint of improving the mechanical strength of the rubber layer (A) and rubber layer (B), and improving the peel strength between rubber layer (A) and rubber layer (B). Furthermore, the acyclic non-conjugated olefin compound is more preferably an α-olefin, even more preferably an α-olefin containing ethylene, and particularly preferably consisting solely of ethylene. In other words, the non-conjugated olefin units in the copolymer are preferably acyclic non-conjugated olefin units, more preferably α-olefin units, even more preferably α-olefin units containing ethylene units, and particularly preferably consisting only of ethylene units.

[0038] 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 high-temperature fracture characteristics of the rubber layer (A) and rubber layer (B) 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.

[0039] 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. A non-conjugated olefin unit content of 40 to 97 mol% of the total copolymer improves the mechanical strength of the rubber layer (A) and rubber layer (B), and also improves the peel strength between rubber layer (A) and rubber layer (B). From the viewpoint of further improving the mechanical strength of the rubber layer (A) and rubber layer (B), and further improving the peel strength between rubber layer (A) and rubber layer (B), the content of non-conjugated olefin units is preferably in the range of 40 to 97 mol% of the total copolymer, more preferably in the range of 45 to 95 mol%, even more preferably in the range of 55 to 90 mol%, and still more preferably in the range of 60 to 90 mol%.

[0040] -Aromatic vinyl units- The copolymer preferably further contains aromatic vinyl units. Aromatic vinyl units are constituent units derived from aromatic vinyl compounds as monomers. The copolymer contains aromatic vinyl units, which cleave crystalline components such as ethylene crystal components and suppress excessive crystallization derived from non-conjugated olefin units. This improves the rigidity of the copolymer while minimizing the loss of elasticity, resulting in high crack resistance and thus improving the crack resistance of rubber layers (A) and (B). Here, an aromatic vinyl compound refers to an aromatic compound substituted with at least a vinyl group, and is not included in conjugated diene compounds. The aromatic vinyl compound preferably has 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 compound may be used alone or in combination of two or more types.

[0041] The aromatic vinyl compound 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 rubber layers (A) and (B). In other words, the aromatic vinyl units in the copolymer preferably contain styrene units, and more preferably consist solely of styrene units. Furthermore, the aromatic ring in an aromatic vinyl unit is not included in the main chain of the copolymer unless it is bonded to an adjacent unit.

[0042] When the copolymer is a ternary copolymer or a polypolymer, the content of aromatic vinyl units is preferably 2 mol% or more, more preferably 3 mol% or more, preferably 35 mol% or less, more preferably 30 mol% or less, and even more preferably 25 mol% or less. A content of aromatic vinyl units of 2 to 35 mol% of the total copolymer improves the mechanical strength of the rubber layer (A) and rubber layer (B). From the viewpoint of further improving the mechanical strength of the rubber layer (A) and rubber layer (B), the content of aromatic vinyl units is preferably in the range of 2 to 35 mol%, more preferably in the range of 3 to 30 mol%, and even more preferably in the range of 3 to 25 mol% of the total copolymer.

[0043] 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., 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 effect, it is preferable that the copolymer has a butylene unit content of 0 mol%.

[0044] From the viewpoint of improving the mechanical strength of the rubber layer (A) and the rubber layer (B), the copolymer is preferably a polymer obtained by polymerizing at least one conjugated diene compound, one non-conjugated olefin compound, and one aromatic vinyl compound as monomers. In other words, the copolymer is preferably a copolymer containing only one type of conjugated diene unit, only one type of non-conjugated olefin unit, and only one type of aromatic vinyl unit; more preferably a ternary copolymer consisting only of one type of conjugated diene unit, only one type of non-conjugated olefin unit, and only 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, "only one type of conjugated diene unit" includes conjugated diene units with different bonding modes.

[0045] 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 unconjugated 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 high-temperature fracture characteristics of the rubber layer (A) and rubber layer (B) can be effectively improved.

[0046] 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, it is possible to improve the flexibility and mechanical strength of the rubber layer (A) and the rubber layer (B) while also improving the peel strength between the rubber layer (A) and the rubber layer (B).

[0047] -Physical properties of copolymers- The copolymer preferably has a number-average molecular weight (Mn) of 10,000 to 9,000,000 (10 to 9,000 kg / mol) on a polystyrene basis, and more preferably 100,000 to 8,000,000 (100 to 8,000 kg / mol). A Mn of 10,000 or more ensures sufficient mechanical strength for the rubber layers (A) and (B), while a Mn of 9,000,000 or less makes it less likely to impair the workability of the composition containing the copolymer.

[0048] 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 for the rubber layers (A) and (B), while a Mw of 10,000,000 or less makes it less likely to impair the workability of the composition containing the copolymer.

[0049] 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.

[0050] 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 the standard substance.

[0051] 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 rubber layers (A) and (B) can be improved. Furthermore, if the endothermic peak energy of the copolymer is 150 J / g or lower, the workability of 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.

[0052] 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 increases, and the crack resistance of the rubber layer (A) and rubber layer (B) can be improved. Furthermore, if the melting point of the copolymer is 120°C or lower, the workability of the composition containing the copolymer is improved. Moreover, if the melting point of the copolymer is 50 to 120°C, the crack resistance of the rubber layer (A) and rubber layer (B) is high, and the workability in the manufacture of the rubber layer (A) and rubber layer (B) is improved. The melting point of the copolymer can be measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121-1987.

[0053] Preferably, the difference between the melting point of the copolymer contained in rubber layer (A) and the melting point of the copolymer contained in rubber layer (B) is 30°C or less. When the difference in the melting points of the copolymers is 30°C or less, the copolymer contained in rubber layer (A) and the copolymer contained in rubber layer (B) can be melted at similar temperatures by heating and solidified at similar temperatures by cooling, thereby further improving the peel strength between rubber layer (A) and rubber layer (B). From the viewpoint of further improving the peel strength between rubber layer (A) and rubber layer (B), it is particularly preferable that the copolymer contained in rubber layer (A) and the copolymer contained in rubber layer (B) have the same melting point.

[0054] 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 -100°C to -10°C. If the glass transition temperature of the copolymer is 0°C or lower, the mechanical strength of the rubber layer (A) and rubber layer (B) can be further improved. The glass transition temperature of the copolymer can be measured using a differential scanning calorimeter in accordance with JIS K 7121-1987.

[0055] 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 rubber layer (A) and rubber layer (B). Furthermore, if the degree of crystallinity of the copolymer is 50% or lower, the workability during kneading and the extrusion processability of the composition containing the copolymer are improved. The degree of crystallinity of the copolymer can be determined by measuring the crystalline melting energy of 100% crystalline polyethylene and the melting peak energy of the copolymer, and 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.

[0056] Preferably, the copolymer consists solely of a non-cyclic structure in its main chain. This further improves the mechanical strength of the rubber layer (A) and rubber layer (B). Furthermore, 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 only 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 or short molecular chains, or both) are linked together like a pendant [see Section 1.34 of "Glossary of Basic Terms in Polymer Science IUPAC Recommendations 1996", Pure Appl. Chem., 68, 2287-2311 (1996)]. Furthermore, the copolymer may have either a linear or branched structure, but a linear structure is preferred.

[0057] The copolymer exhibits excellent mechanical strength, specifically superior fracture strength, puncture resistance, tensile strength, abrasion resistance, crack resistance, and impact resistance. The copolymer also exhibits excellent mechanical strength at low temperatures. Furthermore, since the copolymer exhibits excellent mechanical strength without relying on fillers such as carbon black or silica, it can be colored using colorants, resulting in excellent decorative properties. On the other hand, because the copolymer can interact with fillers, its mechanical strength can be further improved by using fillers. The copolymer contains conjugated diene units and is therefore crosslinkable. The copolymer also contains conjugated diene units and acts as an elastic material, being stretchable and expandable. The copolymer can be injection molded and stretched, and can therefore be processed into a film. Because the copolymer contains conjugated diene units and non-conjugated olefin units, it readily adheres to both resins (olefin resins) and rubbers (diene-based rubbers), and can therefore function as an adhesive between resins and rubbers. Furthermore, 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, such as by pouring hot water at about 80 to 100°C or immersing it in hot water. Furthermore, the copolymer has shape memory properties.

[0058] -Method of 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 the conjugated diene compound and the 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.

[0059] The method for producing the copolymer may further involve a coupling step, a washing step, and other steps, as necessary. The following describes a method for producing a copolymer, using the case of producing a ternary copolymer as an example.

[0060] 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.

[0061] 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.

[0062] The polymerization process may be carried out in one step or in two or more steps. A single polymerization step is a step 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 and polymerized simultaneously. Furthermore, a multi-stage polymerization process is a process in which a polymer is formed by first reacting some or all of one or two types of monomers (first polymerization stage), and then polymerizing by adding monomers of the type not added in the first polymerization stage, the remainder of the monomers added in the first polymerization stage, etc., in one or more stages (second polymerization stage to final polymerization stage). In particular, it is preferable to carry out the polymerization process in multiple stages in the production of the copolymer.

[0063] 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. Furthermore, 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. Furthermore, there are no particular restrictions on the reaction time of the polymerization reaction; for example, a range of 1 second to 10 days is preferred, but it can be appropriately selected depending on conditions such as the type of polymerization catalyst and polymerization temperature. Furthermore, during the polymerization process of the conjugated diene compound, polymerization may be stopped using polymerization inhibitors such as methanol, ethanol, or isopropanol.

[0064] 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.

[0065] 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.

[0066] The first step is preferably carried out in a reactor under the atmosphere of an inert gas, preferably nitrogen or argon. The temperature in the first step (reaction temperature) 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 in the first step is not particularly limited, but in order to sufficiently incorporate the aromatic vinyl compound into the polymerization reaction system, it is preferably in the range of 0.1 to 10.0 MPa. 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.

[0067] 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.

[0068] 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. Furthermore, if the second monomer raw material includes at least one selected from the group consisting of a conjugated diene compound, a non-conjugated olefin compound, and an aromatic vinyl 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. In addition, 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 it continuously to the polymerization mixture (so-called metering). Here, when using a monomer raw material that is a gas under the conditions of the polymerization reaction system (for example, ethylene as a non-conjugated olefin compound under conditions of room temperature and atmospheric pressure), it can be introduced into the polymerization reaction system at a predetermined pressure.

[0069] The second step is preferably carried out in a reactor under an inert gas atmosphere, 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 increasing the reaction temperature may decrease 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. Furthermore, in the second step, the polymerization reaction may be stopped using polymerization inhibitors such as methanol, ethanol, or isopropanol.

[0070] 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) Components: Rare earth element compounds or reaction products of said rare earth element compounds with Lewis bases (b) Component: Organometallic compound (c) Ingredients: Aluminoxane (d) Component: Ionic compound (e) Components: Halogen compounds (f) Components: Cyclopentadiene skeleton-containing compounds selected from substituted or unsubstituted cyclopentadiene (compounds having a cyclopentadienyl group), substituted or unsubstituted indene (compounds having an indenyl group), and substituted or unsubstituted fluorene (compounds having a fluorenyl group). The components (a) to (f) above can be used in the polymerization process, for example, by referring to International Publication No. 2018 / 092733, etc.

[0071] The coupling step is a step in which a reaction (coupling reaction) is carried out to modify at least a portion (for example, the ends) of the polymer chain of the copolymer obtained in the polymerization step. In the coupling process, it is preferable to perform 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 depending on 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. Furthermore, the number-average molecular weight (Mn) of the copolymer can be increased by performing a coupling reaction.

[0072] 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, and isopropanol. However, when using a catalyst derived from a Lewis acid as a 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 process can effectively reduce the amount of catalyst residue in the copolymer.

[0073] (Other ingredients) The rubber layer (A) and rubber layer (B) may contain polymer components other than the above-mentioned rubber components, conjugated diene units, and non-conjugated olefin units, as well as various compounding agents. Examples of compounding agents include functional components such as fillers, reinforcing fibers, antioxidants, softeners, crosslinked packages containing stearic acid, zinc oxide, crosslinking promoters, and crosslinking agents, resins, UV absorbers, foaming agents, and colorants.

[0074] -Filler- The rubber layers (A) and (B) may contain fillers. By including fillers in the rubber layers (A) and (B), the mechanical strength of the rubber layers (A) and (B) can be improved. Examples of the aforementioned fillers include carbon black and inorganic fillers. The type of carbon black is not particularly limited and includes, for example, 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. There are no particular restrictions on the type of silica, and examples include wet silica (hydrated silica), dry silica (anhydrous silica), and colloidal silica. Furthermore, when silica is included as a filler, rubber layers (A) and (B) may further contain a silane coupling agent in order to improve the dispersibility of silica in the rubber layers (A) and (B).

[0075] -Anti-aging agent- The rubber layer (A) and rubber layer (B) may contain an antioxidant. Examples of antioxidants include amine-ketone compounds, imidazole compounds, amine compounds, phenolic compounds, sulfur compounds, and phosphorus compounds.

[0076] -Softener- The rubber layers (A) and (B) may contain a softening agent. Examples of softening agents include petroleum-based softening agents such as process oil, lubricating oil, naphthenic oil, paraffin, liquid paraffin, petroleum asphalt, and petrolatum; fatty oil-based softening agents such as castor oil, linseed oil, rapeseed oil, and coconut oil; and waxes such as beeswax, carnauba wax, and lanolin. These softening agents may be used individually or in combination of two or more.

[0077] -Crosslinking agent- The rubber layer (A) and rubber layer (B) may contain a crosslinking agent. There are no particular restrictions on the crosslinking agent, but common 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.

[0078] -Crosslinking promoter- The rubber layer (A) and rubber layer (B) may contain a crosslinking accelerator. Examples of crosslinking accelerators (vulcanization accelerators) include guazinine-based, sulfenamide-based, thiuram-based, thiazole-based, aldehydeamine-based, and thiocarbamate-based crosslinking accelerators.

[0079] (One embodiment) Next, with reference to Figure 1, a laminate according to one embodiment of the present invention will be described. Figure 1 is a schematic cross-sectional view in the thickness direction showing the laminate of this embodiment. The laminate 1 shown in Figure 1 comprises a rubber layer (A) 2 and a rubber layer (B) 3, with rubber layer (A) 2 and rubber layer (B) 3 being joined together. Although the laminate 1 shown in Figure 1 consists of two layers, rubber layer (A) 2 and rubber layer (B) 3, the laminate of the present invention may consist of three or more layers.

[0080] (Applications of laminates) The laminate of this embodiment can be applied to various rubber products containing at least two rubber layers, in addition to the tires described later.

[0081] <Method for manufacturing laminates> The laminate of this embodiment described above can be manufactured by various methods, for example, (1) two crosslinked rubber layers may be laminated and heated, (2) one crosslinked rubber layer and one uncrosslinked rubber layer may be laminated and heated, or (3) two uncrosslinked rubber layers may be laminated and heated.

[0082] One embodiment of the method for producing a laminate is characterized by laminating at least two crosslinked rubber layers, each containing a rubber component with 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component, and then heating the laminate. According to this method of producing a laminate, a laminate with high interlayer peel strength can be obtained with high productivity.

[0083] Furthermore, the method for manufacturing a laminate according to another embodiment is characterized by laminating at least one crosslinked rubber layer comprising a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component, and at least one uncrosslinked rubber layer comprising a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component, and then heating, and a laminate with high interlayer peel strength can also be obtained with high productivity by this method for manufacturing a laminate. Here, at least one uncrosslinked rubber layer may be crosslinked (vulcanized) by heating. When crosslinking the uncrosslinked rubber layer by heating, it is preferable that the uncrosslinked rubber layer contains the above-mentioned crosslinking agent and crosslinking accelerator.

[0084] Furthermore, a method for manufacturing a laminate according to another embodiment is characterized by laminating at least two uncrosslinked rubber layers, each containing a rubber component with 50% by mass or more of diene rubber and a copolymer having conjugated diene units and unconjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component, and then heating (crosslinking). This method for manufacturing a laminate also yields a laminate with high productivity and high interlayer peel strength. Here, at least two uncrosslinked rubber layers may be crosslinked (vulcanized) by heating. When crosslinking the uncrosslinked rubber layers by heating, it is preferable that the uncrosslinked rubber layers contain the above-mentioned crosslinking agent and crosslinking accelerator.

[0085] The rubber layer (A) and rubber layer (B) can be formed from a rubber composition comprising a rubber component containing 50% by mass or more of the diene-based rubber and a copolymer having the conjugated diene units and non-conjugated olefin units. In addition to the rubber component and the copolymer having the conjugated diene units and non-conjugated olefin units, the rubber composition may also contain the above-mentioned fillers, silane coupling agents, antioxidants, softeners, crosslinking agents, crosslinking accelerators, etc. The rubber composition may be manufactured by mixing only the rubber component and the copolymer, or by mixing the rubber component and the copolymer with any additional components. Alternatively, the rubber component and the copolymer alone, or together with any other optional additive, may be kneaded using a kneader such as a single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, or internal mixer. The mixing of each component may be done in one step or in two or more steps.

[0086] When the components of the rubber composition are melt-kneaded in an extruder and the rubber composition is extruded, the extruded rubber 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, prismatics, and spheres.

[0087] The rubber layer (A) and rubber layer (B) may be manufactured by melting and kneading the rubber composition and then extruding it, or by hot pressing the rubber composition. The hot pressing temperature is preferably 120 to 160°C, and more preferably 130 to 150°C.

[0088] <Tires> The tire of this embodiment is characterized by comprising the laminate of this embodiment described above. Because the tire of this embodiment comprises the laminate of this embodiment, which has high interlayer peel strength and high productivity, it has high durability and high productivity.

[0089] In the tire of this embodiment, one layer of the laminate described above can be used, for example, as a tire repair patch or a tread rubber component of a retreaded tire. Here, if one layer of the laminate corresponds to a tire repair patch, the other layer of the laminate corresponds to a damaged tire. Also, if one layer of the laminate corresponds to a tread rubber component of a retreaded tire, the other layer of the laminate corresponds to a base tire prepared by removing the worn tread rubber from a tire.

[0090] Conventional methods can be used to manufacture the aforementioned tire. For example, components commonly used in tire manufacturing, such as a carcass layer, belt layer, and tread rubber, consisting of an uncrosslinked rubber composition and / or cords, are sequentially layered on a tire molding drum, and the drum is removed to obtain a green tire. Then, by crosslinking this green tire, a desired tire (for example, a pneumatic tire) can be manufactured.

[0091] Furthermore, if a tire is damaged, the damaged portion of the tire is treated as rubber layer (B), rubber layer (A) is laminated onto rubber layer (B), and if desired, heating is applied to fix rubber layer (A) to rubber layer (B), thereby repairing the tire.

[0092] Furthermore, a retreaded tire can be manufactured by removing the tread rubber from a used tire to obtain a base tire, making the outermost layer of the base tire a rubber layer (B), and preparing a tread rubber material for retreading as a rubber layer (A), and laminating rubber layer (A) onto rubber layer (B). [Examples]

[0093] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0094] <Synthesis of copolymers having conjugated diene units and non-conjugated olefin units> (Synthesis of copolymer 1) 75g of styrene and 675g of toluene were added to a thoroughly dried 2000mL pressure-resistant stainless steel reactor. Meanwhile, in a glove box under a nitrogen atmosphere, 0.075 mmol of ((1-benzyldimethylsilyl-3-methyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {(1-BnMe2Si-3-Me]C9H5Gd[N(SiHMe2)2]2}, 0.083 mmol of dimethylanilinium tetrakis(pentafluorophenyl)borate [Me2NHPhB(C6F5)4], and 0.35 mmol of diisobutylaluminum hydride were added to a glass container, and then 30 g of toluene was added to prepare the catalyst solution. The resulting 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 a 5% by mass isopropanol solution 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. Next, the copolymer was separated using a large amount of methanol and vacuum-dried at 50°C to obtain copolymer 1.

[0095] (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, 0.075 mmol of mono(1,3-bis(tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1,3-[(t-Bu)Me2Si]2C9H5Gd[N(SiHMe2)2]2}, 0.075 mmol of dimethylanilinium tetrakis(pentafluorophenyl)borate [Me2NHPhB(C6F5)4], and 0.35 mmol of diisobutylaluminum hydride were added to a glass container, and then 20 mL of toluene was added to prepare the catalyst solution. The resulting 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 a 5% by mass isopropanol solution 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. Next, the copolymer was separated using a large amount of methanol and vacuum-dried at 50°C to obtain copolymer 2.

[0096] <Method for measuring the physical properties of copolymers> The following physical properties were measured for the synthesized copolymer. The results are shown in Table 1.

[0097] (1) Number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) Gel permeation chromatography [GPC: Tosoh HLC-8121GPC / HT, Column: Tosoh GMH] HR Using two H(S)HT tubes and a differential refractometer (RI) as the detector, the number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) of the copolymer were determined relative to monodisperse polystyrene. The measurement temperature was 40°C.

[0098] (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 as follows: 1 The integral ratio of each peak in the 1H-NMR spectrum (100°C, d-tetrachloroethane standard: 6 ppm) was determined.

[0099] (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.

[0100] (4) Content of 1,4-links in butadiene units The 1,2- and 3,4-bonds were determined using infrared radiation (Morello method), and the 1,4-bond content was calculated by determining the total amount of 1,2- and 3,4-bonds from 100%.

[0101] (5) Glass transition temperature (Tg) The glass transition temperature (Tg) 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.

[0102] (6) Endothermic peak energy Using a differential scanning calorimeter (DSC, manufactured by T.A. Instruments Japan, "DSCQ2000"), the obtained copolymer was heated from -150°C to 150°C at a rate of 10°C / min in accordance with JIS K 7121-1987. The endothermic peak energy (ΔH1 (J / g)) in the range of 0°C to less than 100°C and the endothermic peak energy (ΔH2 (J / g)) in the range of 100°C to 150°C were then measured (1st run).

[0103] (7) Degree of crystallinity The crystalline melting energy of 100% crystalline polyethylene and the melting peak energy of the resulting copolymer at 0-120°C were measured, and the degree of crystallinity was calculated from the energy ratio of polyethylene to copolymer. The melting peak energy was measured using a differential scanning calorimeter (DSC, "DSCQ2000" manufactured by T.A. Instruments Japan).

[0104] (8) Tensile strength (Tb) and elongation at break (Eb) The specimens were molded into a dumbbell-shaped No. 3 form according to JIS K 6251 (2017) and used as test pieces. Tensile strength (Tb) was measured according to JIS K 6251 (2017) using a tensile testing apparatus (manufactured by Instron), by elongating the test specimen to 100% at 25°C and measuring the maximum tensile force required to break the specimen. The elongation at break (Eb) was determined by stretching the specimen at a speed of 100 mm / min at 25°C, measuring the length at which the specimen broke, and calculating the length relative to the length before stretching (100%).

[0105] (9) Confirmation of the main chain structure Regarding the synthesized copolymer, 13 By measuring the 1C NMR spectrum, 13 The absence of peaks in the 10-24 ppm range in the 1C-NMR spectrum chart confirmed that the synthesized copolymer consists solely of acyclic structures in its main chain.

[0106] [Table 1]

[0107] <Preparation of rubber composition> A rubber composition was prepared by blending, kneading, and vulcanizing each component according to the formulation shown in Table 2. The types and amounts of copolymers containing conjugated diene units and non-conjugated olefin units blended are shown in Table 3.

[0108] [Table 2]

[0109] *1 NR: Natural rubber *2 BR: Butadiene rubber, manufactured by UBE Elastomers, product name "UBEPOL BR150L" *3 Carbon Black: N134 *4 Vulcanization chemicals: Contains vulcanization accelerators and sulfur. *5 Other ingredients: Contains stearic acid and zinc oxide.

[0110] <Fabrication and evaluation of laminates> Rubber layers (A) and (B) were prepared from the rubber composition prepared as described above. Rubber layers (A) and (B) were laminated together and heated at 140°C for 2 minutes to bond them and create a laminate. The peel strength of the obtained laminate was measured using the following method.

[0111] (10) Measurement of peel strength The rubber layer (B) of the laminate was peeled off from the rubber layer (A), and the peeling resistance (N / 10mm) was measured. The measurement results were expressed as an index, with the peel strength of the laminate in Example 1 set to 100. A higher index value indicates higher peel strength. Furthermore, the peel strength of each example was classified according to the following criteria. Excellent: When the index value is 150 or higher. Good: When the index value is between 100 and less than 150. OK: When the index value is less than 100 but 50 or greater. Not allowed: If the index value is less than 50 The results are shown in Table 3.

[0112] [Table 3]

[0113] Table 3 shows that a laminate made from a rubber layer (A) containing a rubber component with 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, and a rubber layer (B) containing a rubber component with 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, exhibits high peel strength between rubber layer (A) and rubber layer (B). [Industrial applicability]

[0114] The laminate of this embodiment can be used in various rubber products such as tires.

[0115] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 7 Affordable and Clean Energy," "No. 12 Responsible Consumption and Production," and "No. 13 Climate Action." [Explanation of Symbols]

[0116] 1: Laminate, 2: Rubber layer (A), 3: Rubber layer (B)

Claims

1. A laminate comprising at least two rubber layers, A laminate characterized in that one rubber layer (A) and another rubber layer (B) adjacent to the rubber layer (A) each contain a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the content of the copolymer is 3 to 40 parts by mass per 100 parts by mass of the rubber component.

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

3. The laminate 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 laminate according to claim 1, wherein the copolymer further comprises aromatic vinyl units.

5. The laminate according to claim 4, wherein the copolymer has a content of 1 to 50 mol% of the conjugated diene units, a content of 40 to 97 mol% of the unconjugated olefin units, and a content of 2 to 35 mol% of the aromatic vinyl units.

6. The laminate according to claim 1, wherein the copolymer has a degree of crystallinity of 0.5 to 50%.

7. The laminate according to claim 1, wherein the difference between the melting point of the copolymer contained in the rubber layer (A) and the melting point of the copolymer contained in the rubber layer (B) is 30°C or less.

8. A method for producing a laminate, characterized by laminating at least two crosslinked rubber layers, each containing a rubber component with 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component, and then heating the laminate.

9. A method for producing a laminate, characterized by laminating and heating: a crosslinked rubber layer comprising a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component; and an uncrosslinked rubber layer comprising a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component.

10. A method for producing a laminate, characterized by laminating at least two rubber layers, one containing a rubber component with 50% by mass or more of diene rubber and the other a copolymer having conjugated diene units and non-conjugated olefin units, wherein the copolymer content is 3 to 40 parts by mass per 100 parts by mass of the rubber component, and then heating the laminate.

11. A tire characterized by comprising the laminate described in claim 1.

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