WO2024134952A1

WO2024134952A1 - Laminate, method for producing laminate, and tire

Info

Publication number: WO2024134952A1
Application number: PCT/JP2023/027074
Authority: WO
Inventors: 健山口; 真紀子竹重; 昭二郎会田; 紀彦加賀; 悟司浜谷; 真橋口
Original assignee: 株式会社ブリヂストン
Priority date: 2022-12-19
Filing date: 2023-07-24
Publication date: 2024-06-27

Abstract

The present invention addresses the problem of providing a laminate having a high interlaminar release strength and high producibility. The laminate (1) comprises at least two rubber layers, and is characterized in that one rubber layer (A) (2) in the laminate (1) and another rubber layer (B) (3) adjoining the rubber layer (A) (2) each comprise a rubber component, which includes 50 mass% or more diene-based rubber, and a copolymer, which comprises a conjugated diene unit and a non-conjugated olefin unit, and that the content of the copolymer is 3-40 parts by mass per 100 parts by mass of the rubber component.

Description

Laminate, method for manufacturing laminate, and tire

The present invention relates to a laminate, a method for manufacturing a laminate, and a tire.

　Traditionally, a tire has been repaired by attaching a repair patch made of unvulcanized rubber to the damaged area of the tire and heating it at high temperatures to adhere to the damaged area. Also, when the tread rubber of a tire wears out, it is common to physically scrape off the worn tread rubber (the so-called buffing process) to obtain a base tire, and then bond a precured tread (a tread rubber member that has been vulcanized in advance) to the base tire to retread the tire. In this way, it is widely practiced to bond vulcanized rubber to unvulcanized rubber, or to bond vulcanized rubber to vulcanized rubber, and there is a demand for technology that improves the adhesion (peel strength) between rubber layers.

For example, Patent Document 1 listed below discloses a method for bonding vulcanized rubber and unvulcanized rubber, in which a bonding portion on the vulcanized rubber side is subjected to a plasma treatment, and then the vulcanized rubber and the unvulcanized rubber are vulcanized and bonded together.
Furthermore, the following Patent Document 2 discloses that a pre-treatment such as buffing is performed on the surface of the pre-cured tread that is to be bonded to the base tire.

JP 2007-217559 A Japanese Patent Application Publication No. 5-116235

As mentioned above, various pretreatments have been used to improve adhesion (peel strength) between rubber layers, but these pretreatments take time, and improvements are needed from the perspective of productivity.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a laminate having high interlayer peel strength and high productivity.
Another object of the present invention is to provide a method for producing such a laminate, and a tire which includes such a laminate and has high durability and can be produced with high productivity.

The laminate, laminate manufacturing method, and tire of the present invention that solve the above problems are summarized below.

[1] A laminate including at least two rubber layers,
A laminate, characterized in that one rubber layer (A) in the laminate and another rubber layer (B) adjacent to the rubber layer (A) each contain 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 per 100 parts by mass of the rubber component.

[2] The laminate described in [1], wherein the copolymer has a melting point of 50 to 120°C.

[3] The laminate according to [1] or [2], wherein the copolymer has a content of the conjugated diene units of more than 0 mol% and not more than 50 mol%, and a content of the non-conjugated olefin units of 50 mol% or more and less than 100 mol%.

[4] The laminate according to any one of [1] to [3], wherein the copolymer further contains an aromatic vinyl unit.

[5] The laminate according to [4], wherein the copolymer has a conjugated diene unit content of 1 to 50 mol%, a non-conjugated olefin unit content of 40 to 97 mol%, and an aromatic vinyl unit content of 2 to 35 mol%.

[6] The laminate according to any one of [1] to [5], wherein the copolymer has a crystallinity of 0.5 to 50%.

[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.

[8] A method for producing a laminate, comprising laminating and heating at least two crosslinked rubber layers, the rubber layers including a rubber component containing 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content being 3 to 40 parts by mass per 100 parts by mass of the rubber component.

[9] A method for producing a laminate, comprising laminating and heating at least one cross-linked rubber layer, the rubber layer including a rubber component containing 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content being 3 to 40 parts by mass per 100 parts by mass of the rubber component, and at least one uncross-linked rubber layer, the rubber component including 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content being 3 to 40 parts by mass per 100 parts by mass of the rubber component.

[10] A method for producing a laminate, comprising laminating and heating at least two uncrosslinked rubber layers, the rubber layers including a rubber component containing 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content being 3 to 40 parts by mass per 100 parts by mass of the rubber component.

[11] A tire comprising a laminate according to any one of [1] to [7].

According to the present invention, it is possible to provide a laminate having high interlayer peel strength and high productivity.
Furthermore, according to the present invention, it is possible to provide a method for producing such a laminate, and a tire which includes such a laminate and has high durability and high productivity.

1 is a cross-sectional view in a thickness direction, which diagrammatically illustrates a laminate of the present embodiment.

The laminate, the method for manufacturing the laminate, and the tire of the present invention are described in detail below with reference to examples based on the embodiments.

<Definition>
The compounds described herein may be derived in whole or in part from fossil sources, from biological sources such as plant sources, from recycled sources such as used tires, or from a mixture of two or more of fossil sources, biological sources, and/or renewable sources.

In this specification, copolymers having conjugated diene units and non-conjugated olefin units are distinguished from rubber components, i.e., "rubber components" excludes "copolymers having conjugated diene units and non-conjugated olefin units."

<Laminate>
The laminate of the present embodiment is a laminate including at least two rubber layers, and is characterized in that one rubber layer (A) in the laminate and another rubber layer (B) adjacent to the rubber layer (A) each include a rubber component including 50% by mass or more of a diene rubber and a copolymer having a conjugated diene unit and a non-conjugated olefin unit (hereinafter, sometimes simply referred to as a "copolymer"), and the content of the copolymer is 3 to 40 parts by mass relative to 100 parts by mass of the rubber component.

In the laminate of this embodiment, both the adjacent rubber layers (A) and (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. The copolymer can be melted, for example, by heating and bonded with high adhesive strength, and therefore the peel strength between the rubber layers (A) and (B) is high.
In addition, the copolymer having conjugated diene units and non-conjugated olefin units melts, for example, by heating. Therefore, even without subjecting the rubber layer (A) and/or the rubber layer (B) to a pretreatment, the rubber layer (A) and the rubber layer (B) can be easily bonded to each other by laminating the rubber layer (A) and the rubber layer (B) and heating the laminate.
Therefore, the laminate of this embodiment has high peel strength between the rubber layer (A) and the rubber layer (B) and also has high productivity.

The laminate of the present embodiment includes at least two rubber layers, and the thickness of each rubber layer is not particularly limited and is, for example, 1 mm or more. The upper limit of the thickness is also not particularly limited and is, for example, 2000 mm or less.
In the laminate of this embodiment, 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 a diene rubber and a copolymer having a conjugated diene unit and a non-conjugated olefin unit. In addition, it is sufficient that the adjacent rubber layers (A) and (B) in the laminate contain 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 when the laminate is composed 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 the rubber layer (A) and/or the rubber layer (B).

(Rubber component)
The rubber layer (A) and the rubber layer (B) each contain a rubber component containing 50% by mass or more of a diene rubber. As described above, the rubber component excludes the copolymer having a conjugated diene unit and a non-conjugated olefin unit. The rubber component provides rubber elasticity to the rubber layer (A) and the rubber layer (B).
Examples of the diene rubber include natural rubber (NR) and synthetic diene rubber. Specific examples of the synthetic diene rubber include synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), halogenated butyl rubber, and acrylonitrile-butadiene rubber (NBR). The diene rubber may be used alone or in combination of two or more. The diene rubber may be modified.
The rubber component may contain a non-diene rubber in addition to the diene rubber. Here, the ratio of the diene rubber in the rubber component is 50% by mass or more, and may be 100% by mass. When the ratio of the diene rubber in the rubber component is 50% by mass or more, the rubber layer (A) and the rubber layer (B) have sufficient rubber elasticity.

(Copolymers Having Conjugated Diene Units and Non-Conjugated Olefin Units)
The copolymer having a conjugated diene unit and a non-conjugated olefin unit may be a binary copolymer consisting of two units, a conjugated diene unit and a non-conjugated olefin unit, or may be a ternary copolymer consisting of three units including an aromatic vinyl unit, or may be a multi-component copolymer containing other monomer units.

The rubber layer (A) and the rubber layer (B) are each characterized in that the content of the copolymer 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 content of the copolymer is 3 parts by mass or more per 100 parts by mass of the rubber component, the peel strength between the rubber layer (A) and the rubber layer (B) and the mechanical strength of the rubber layer (A) and the rubber layer (B) are improved, and if the content is 40 parts by mass or less, the flexibility of the rubber layer (A) and the rubber layer (B) is improved.

The difference between the content of the copolymer contained in the rubber layer (A) and the content of the copolymer contained in the rubber layer (B) is preferably 20 parts by mass or less, based on 100 parts by mass of the rubber component. When the difference in the content of the copolymer in the rubber layer (A) and the rubber layer (B) is 20 parts by mass or less, the physical properties of the rubber layer (A) and the rubber layer (B) tend to be similar, making it easy to improve the peel strength between the rubber layer (A) and the rubber layer (B).
In addition, from the viewpoint of peel strength between the rubber layer (A) and the rubber layer (B), it is more preferable that the content of the copolymer contained in the rubber layer (A) is equal to the content of the copolymer contained in the rubber layer (B).

- Conjugated diene units -
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, and 2,3-dimethyl-1,3-butadiene. The conjugated diene compound may be used alone or in combination of two or more kinds.

From the viewpoint of improving the mechanical strength of the rubber layer (A) and the rubber layer (B), 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 further 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 at least one selected from the group consisting of 1,3-butadiene units and isoprene units, and further preferably consists of only 1,3-butadiene units.

When the copolymer is a binary copolymer, the content of conjugated diene units is preferably more than 0 mol% and not more than 50 mol%. In this case, a copolymer with excellent elongation and weather resistance can be obtained. From the same viewpoint, it is more preferable that the proportion of conjugated diene units in the binary copolymer is not more than 40 mol%.

In the binary copolymer, the ratio of 1,2 adducts (including 3,4 adducts) of the conjugated diene units is preferably 10 mol% or less. If the ratio is 10 mol% or less, the heat resistance and flex fatigue resistance of the copolymer can be improved. From the same viewpoint, the ratio of 1,2 adducts (including 3,4 adducts) of the conjugated diene units in the binary copolymer is more preferably 8 mol% or less, and even more preferably 6 mol% or less. Note that the ratio of 1,2 adducts (including 3,4 adducts) of the conjugated diene units is the ratio in the entire conjugated diene units, not the ratio in the entire copolymer. Furthermore, when the conjugated diene units are butadiene units, the ratio has the same meaning as the 1,2-vinyl bond amount.

When the copolymer is a terpolymer or a multicomponent copolymer, the content of the conjugated diene unit is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, and is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less.
When the content of the conjugated diene unit is 1 to 50 mol % of the entire copolymer, the flexibility and mechanical strength of the rubber layer (A) and the rubber layer (B) can be improved.
From the viewpoint of further improving the flexibility and mechanical strength of the rubber layer (A) and the rubber layer (B), the content of the conjugated diene unit 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 entire copolymer.

-Non-conjugated olefin units-
The non-conjugated olefin unit is a structural unit derived from a non-conjugated olefin compound as a monomer.
Here, the non-conjugated olefin compound refers to an aliphatic unsaturated hydrocarbon compound 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 compounds may be used alone or in combination of two or more kinds.

The non-conjugated olefin compound as a monomer of the copolymer is preferably a non-cyclic non-conjugated olefin compound from the viewpoints of improving the mechanical strength of the rubber layer (A) and the rubber layer (B) and also improving the peel strength between the rubber layer (A) and the rubber layer (B). The non-cyclic non-conjugated olefin compound is more preferably an α-olefin, further preferably an α-olefin containing ethylene, and particularly preferably composed of only ethylene.
In other words, the non-conjugated olefin units in the copolymer are preferably non-cyclic non-conjugated olefin units, and the non-cyclic non-conjugated olefin units are more preferably α-olefin units, further preferably α-olefin units containing ethylene units, and particularly preferably consisting of only ethylene units.

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 properties of the rubber layer (A) and the rubber layer (B) at high temperatures can be effectively improved. From the same viewpoint, it is more preferable that the proportion of non-conjugated olefin units in the binary copolymer is 60 mol% or more.

When the copolymer is a terpolymer or a multicomponent copolymer, the content of the non-conjugated olefin unit 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 is preferably 97 mol% or less, more preferably 95 mol% or less, and even more preferably 90 mol% or less. When the content of the non-conjugated olefin unit is 40 to 97 mol% of the entire copolymer, the mechanical strength of the rubber layer (A) and the rubber layer (B) can be improved, and the peel strength between the rubber layer (A) and the rubber layer (B) can be improved.
From the viewpoint of further improving the mechanical strength of the rubber layer (A) and the rubber layer (B) and further improving the peel strength between the rubber layer (A) and the rubber layer (B), the content of the non-conjugated olefin unit is preferably in the range of 40 to 97 mol %, 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 %, of the entire copolymer.

- Aromatic vinyl unit -
The copolymer preferably further contains an aromatic vinyl unit.
The aromatic vinyl unit is a structural unit derived from an aromatic vinyl compound as a monomer.
When the copolymer contains an aromatic vinyl unit, crystalline components such as ethylene crystalline components are cut, and excessive crystallization derived from non-conjugated olefin units is suppressed. While improving the rigidity of the copolymer, elasticity is not easily impaired, and high crack resistance can be obtained, and the crack resistance of the rubber layer (A) and the rubber layer (B) can be improved.
Here, the aromatic vinyl compound refers to an aromatic compound substituted with at least a vinyl group, and is not included in the conjugated diene compound. 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 a single type or a combination of two or more types.

From the viewpoint of improving the mechanical strength of the rubber layer (A) and the rubber layer (B), the aromatic vinyl compound as a monomer of the copolymer preferably contains styrene, and more preferably consists of only styrene. In other words, the aromatic vinyl unit in the copolymer preferably contains a styrene unit, and more preferably consists of only styrene unit.
Incidentally, 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.

When the copolymer is a terpolymer or a multicomponent copolymer, the content of the aromatic vinyl unit is preferably 2 mol% or more, more preferably 3 mol% or more, and preferably 35 mol% or less, more preferably 30 mol% or less, and even more preferably 25 mol% or less. When the content of the aromatic vinyl unit is 2 to 35 mol% of the entire copolymer, the mechanical strength of the rubber layer (A) and the rubber layer (B) can be improved.
From the viewpoint of further improving the mechanical strength of the rubber layer (A) and the rubber layer (B), the content of the aromatic vinyl unit 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 entire copolymer.

From the viewpoint of obtaining the desired effect of the present invention, the content of other structural units than the conjugated diene unit, the non-conjugated olefin unit, and the aromatic vinyl unit is preferably 30 mol% or less of the entire copolymer, more preferably 20 mol% or less, and even more preferably 10 mol% or less, and it is particularly preferable that no other structural units are contained, that is, the content is 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.
In order to reliably obtain the desired effects, the copolymer preferably has a butylene unit content of 0 mol %.

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 kind of conjugated diene compound, one kind of non-conjugated olefin compound, and one kind of 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 of only 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 of only 1,3-butadiene units, ethylene units, and styrene units. Here, "only one type of conjugated diene unit" includes conjugated diene units having different bonding modes.

When the copolymer is, for example, a binary copolymer, it is preferable that the content of conjugated diene units is more than 0 mol% and not more than 50 mol%, and the content of non-conjugated olefin units is 50 mol% or more and less than 100 mol%. In this case, a copolymer having excellent elongation and weather resistance can be obtained, and the fracture properties at high temperatures of the rubber layer (A) and the rubber layer (B) can be effectively improved.

Furthermore, when the copolymer is, for example, a terpolymer, it is preferable that the content of conjugated diene units is 1 to 50 mol%, the content of non-conjugated 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 improving the peel strength between the rubber layer (A) and the rubber layer (B).

- Physical properties of copolymers -
The copolymer preferably has a polystyrene-equivalent number average molecular weight (Mn) of 10,000 to 9,000,000 (10 to 9,000 kg/mol), more preferably 100,000 to 8,000,000 (100 to 8,000 kg/mol). When the copolymer has an Mn of 10,000 or more, the mechanical strength of the rubber layer (A) and the rubber layer (B) can be sufficiently ensured, and when the Mn is 9,000,000 or less, the workability of the composition containing the copolymer is not easily impaired.

The copolymer preferably has a weight average molecular weight (Mw) in terms of polystyrene 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). By having the Mw of the copolymer of 10,000 or more, the mechanical strength of the rubber layer (A) and the rubber layer (B) can be sufficiently ensured, and by having the Mw of 10,000,000 or less, the workability of the composition containing the copolymer is unlikely to be impaired.

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 achieved in the physical properties of the copolymer.

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.

The copolymer preferably has an endothermic peak energy of 10 to 150 J/g, 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 more, the crystallinity of the copolymer is high, and the crack resistance of the rubber layer (A) and the rubber layer (B) can be improved. If the endothermic peak energy of the copolymer is 150 J/g or less, the workability of a composition containing the copolymer is improved.
The endothermic peak energy of the copolymer may be measured by using a differential scanning calorimeter in accordance with JIS K 7121-1987, for example, by increasing the temperature from −150° C. to 150° C. at a rate of 10° C./min.

The copolymer has a melting point of preferably 50 to 120°C, more preferably 50 to 110°C. When the melting point of the copolymer is 50°C or higher, the crystallinity of the copolymer is high, and the crack resistance of the rubber layer (A) and the rubber layer (B) can be improved. When the melting point of the copolymer is 120°C or lower, the workability of the composition containing the copolymer is improved. When the melting point of the copolymer is 50 to 120°C, the crack resistance of the rubber layer (A) and the rubber layer (B) is high, and the workability in the production of the rubber layer (A) and the rubber layer (B) is improved.
The melting point of the copolymer may be measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121-1987.

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

The copolymer preferably has a glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) of 0° C. or lower, more preferably −100° C. to −10° C. When the copolymer has a glass transition temperature of 0° C. or lower, the mechanical strength of the rubber layer (A) and the rubber layer (B) 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.

The copolymer preferably has a crystallinity of 0.5 to 50%, more preferably 3 to 45%, and even more preferably 5 to 45%. When the copolymer has a crystallinity of 0.5% or more, the crystallinity of the copolymer resulting from the non-conjugated olefin units can be sufficiently ensured, and the mechanical strength of the rubber layer (A) and the rubber layer (B) can be further improved. When the copolymer has a crystallinity of 50% or less, the workability during kneading of the composition containing the copolymer and the extrusion processability are improved.
The 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 calculating the crystallinity from the energy ratio between the polyethylene and the copolymer. The melting peak energy can be measured by a differential scanning calorimeter.

The copolymer preferably has a main chain consisting solely of acyclic structures, which can further improve the mechanical strength of the rubber layer (A) and the rubber layer (B).
In addition, NMR is used as a main measurement means for confirming whether the main chain of the copolymer has a cyclic structure or not. Specifically, when no peaks derived from the cyclic structure present in the main chain (for example, peaks appearing at 10 to 24 ppm for three- to five-membered rings) are observed, it indicates that the main chain of the copolymer is composed of only a non-cyclic structure.
In this specification, the main chain of a polymer means a linear molecular chain in which all other molecular chains (long molecular chains or short molecular chains, or both) are linked like pendants [see Section 1.34 of "Glossary of Basic Terms in Polymer Science IUPAC Recommendations 1996", Pure Appl. Chem., 68, 2287-2311 (1996)].
The copolymer may have either a linear or branched structure, but is preferably a linear structure.

The copolymer has excellent mechanical strength, specifically, excellent breaking strength, puncture strength, tensile strength, abrasion resistance, crack resistance, impact resistance, etc. The copolymer also has excellent mechanical strength at low temperatures.
Furthermore, the copolymer has excellent mechanical strength without relying on fillers such as carbon black, silica, etc., and can be colored with a colorant, leading to excellent decorative properties. On the other hand, the copolymer can interact with a filler, so that the mechanical strength can be further improved by using the filler.
The copolymer contains conjugated diene units, and therefore can be crosslinked. The copolymer contains conjugated diene units, and therefore can act as an elastic body and can be stretched. The copolymer can be injection molded and stretched, and therefore can be processed into a film. The copolymer contains conjugated diene units and non-conjugated olefin units, and therefore can easily adhere to both resins (olefin resins) and rubbers (diene rubbers), and therefore can function as an adhesive between resins and rubbers. The copolymer can be foamed. As described above, the melting point of the copolymer is preferably 50 to 120°C, and the shape can be restored by pouring hot water of about 80 to 100°C on the copolymer or by heating the copolymer to the extent of immersing the copolymer in hot water. The copolymer also has shape memory properties.

- Copolymer manufacturing method -
When producing a binary copolymer consisting of two units, a conjugated diene unit and a non-conjugated olefin unit, as the copolymer, the copolymer can be produced through a polymerization process using a conjugated diene compound and a non-conjugated olefin compound as monomers.
Furthermore, when a terpolymer consisting of three units, a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, is produced as the copolymer, the copolymer can be produced through a polymerization process using a conjugated diene compound, a non-conjugated olefin compound, and an aromatic vinyl compound as monomers.

The method for producing the copolymer may further include a coupling step, a washing step, and other steps, if necessary.
Hereinafter, the method for producing a copolymer will be described by taking the case of producing a terpolymer as a representative example.

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

As a polymerization method, any method such as solution polymerization, suspension polymerization, liquid phase bulk polymerization, emulsion polymerization, gas phase polymerization, solid phase polymerization, etc. can be used. In addition, when a solvent is used in the polymerization reaction, the solvent may be any solvent that is inert in the polymerization reaction, such as toluene, cyclohexane, normal hexane, etc.

The polymerization step may be carried out in one stage or in two or more stages.
The one-stage polymerization process is a process in which all types of monomers to be polymerized, i.e., a conjugated diene compound, a non-conjugated olefin compound, an aromatic vinyl compound, and other monomers, preferably a conjugated diene compound, a non-conjugated olefin compound, and an aromatic vinyl compound, are reacted and polymerized simultaneously.
A multi-stage polymerization process is a process in which one or two types of monomers are first reacted in part or in whole to form a polymer (first polymerization stage), and then one or more stages (second polymerization stage to final polymerization stage) are carried out in which a type of monomer not added in the first polymerization stage, the remainder of the monomer added in the first polymerization stage, etc. are added and polymerized. In particular, in the production of the copolymer, it is preferable to carry out the polymerization process in multiple stages.

In the polymerization step, 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 is preferably in the range of -100°C to 200°C, and can 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 not particularly limited, and is preferably in the range of, for example, 1 second to 10 days, but can be appropriately selected depending on conditions such as the type of polymerization catalyst and polymerization temperature.
In the polymerization step of the conjugated diene compound, the polymerization may be terminated using a polymerization terminator such as methanol, ethanol, isopropanol, or the like.

The polymerization process is preferably carried out in multiple stages. More preferably, a first step is carried out in which a first monomer raw material containing at least an aromatic vinyl compound is mixed with a polymerization catalyst to obtain a polymerization mixture, and a second step is carried out in which a second monomer raw material containing at least one selected from the group consisting of a conjugated diene compound, a non-conjugated olefin compound, and an aromatic vinyl compound is introduced into the polymerization mixture. Furthermore, it is 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.

The first monomer raw material used in the first step may contain a non-conjugated olefin compound together with the aromatic vinyl compound. The first monomer raw material may contain the entire amount of the aromatic vinyl compound used, or may contain only a portion of the aromatic vinyl compound. The non-conjugated olefin compound is contained in at least one of the first monomer raw material and the second monomer raw material.

The first step is preferably carried out in a reactor under an 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 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 is preferably in the range of 5 to 500 minutes, for example, when the reaction temperature is 25 to 80°C.

In the first step, any method can be used as the polymerization method for obtaining the polymerization mixture, such as solution polymerization, suspension polymerization, liquid phase bulk polymerization, emulsion polymerization, gas phase polymerization, solid phase polymerization, etc. In addition, when a solvent is used in the polymerization reaction, the solvent may be any solvent that is inert in the polymerization reaction, such as toluene, cyclohexanone, normal hexane, etc.

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.
In addition, when the second monomer raw material contains at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound in addition to the conjugated diene compound, these monomer raw materials may be mixed together with a solvent or the like in advance 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 successively.
In the second step, the method of introducing the second monomer raw material into the polymerization mixture is not particularly limited, but it is preferable to control the flow rate of each monomer raw material and continuously add it to the polymerization mixture (so-called metering). Here, when a monomer raw material that is gaseous under the conditions of the polymerization reaction system (for example, ethylene as a non-conjugated olefin compound under the conditions of room temperature and normal pressure) is used, it can be introduced into the polymerization reaction system at a predetermined pressure.

The second step is preferably carried out in a reactor under an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The temperature (reaction temperature) in the second step is not particularly limited, but is preferably in the range of -100°C to 200°C, and can be about room temperature. If the reaction temperature is increased, the selectivity of the cis-1,4 bond in the conjugated diene unit may decrease. The pressure in the second step is not particularly limited, but is preferably in the range of 0.1 to 10.0 MPa 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 the reaction temperature, but is preferably in the range of 0.1 hours to 10 days, for example.
In the second step, the polymerization reaction may be terminated using a polymerization terminator such as methanol, ethanol, or isopropanol.

Here, the polymerization step of the above-mentioned conjugated diene compound, non-conjugated olefin compound, and aromatic vinyl compound preferably includes a step of polymerizing various monomers in the presence of one or more of the following components (a) to (f) as a catalyst component. Note that, in the polymerization step, it is preferable to use one or more of the following components (a) to (f), but it is more preferable to use a combination of two or more of the following components (a) to (f) as a catalyst composition.
(a) component: a rare earth element compound or a reaction product of the rare earth element compound and a Lewis base (b) component: an organometallic compound (c) component: an aluminoxane (d) component: an ionic compound (e) component: a halogen compound (f) component: a cyclopentadiene skeleton-containing compound selected from substituted or unsubstituted cyclopentadiene (a compound having a cyclopentadienyl group), substituted or unsubstituted indene (a compound having an indenyl group), and substituted or unsubstituted fluorene (a compound having a fluorenyl group). The above (a) to (f) components can be used in the polymerization step, for example, by referring to International Publication No. WO 2018/092733.

The coupling step is a step of carrying out a reaction (coupling reaction) for modifying at least a part (for example, an end) 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%.
The coupling agent used in the coupling reaction is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include tin-containing compounds such as bis(1-octadecylmaleate)dioctyltin(IV), isocyanate compounds such as 4,4'-diphenylmethane diisocyanate, alkoxysilane compounds such as glycidylpropyltrimethoxysilane, etc. These may be used alone or in combination of two or more kinds.
Among these, bis(1-octadecylmaleate)dioctyltin(IV) is preferred in terms of reaction efficiency and low gel formation.
By carrying out the coupling reaction, the number average molecular weight (Mn) of the copolymer can be increased.

The washing step is a step of washing the copolymer obtained in the polymerization step.
The medium used for washing is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include methanol, ethanol, isopropanol, etc., but when a catalyst derived from a Lewis acid is used 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 an amount of 15 mol% or less, the acid is unlikely to remain in the copolymer and is unlikely to adversely affect the reaction during kneading and vulcanization of the composition.
This washing step makes it possible to suitably reduce the amount of catalyst residue in the copolymer.

(Other ingredients)
The rubber layer (A) and the rubber layer (B) may contain polymer components other than the above-mentioned rubber component and the copolymer having a conjugated diene unit and a non-conjugated olefin unit, and various compounding agents, such as functional components such as fillers, reinforcing fibers, antioxidants, softeners, crosslinking packages containing stearic acid, zinc oxide, crosslinking accelerators and crosslinking agents, resins, ultraviolet absorbers, foaming agents, and colorants.

-filler-
The rubber layer (A) and the rubber layer (B) may contain a filler. When the rubber layer (A) and the rubber layer (B) contain a filler, the mechanical strength of the rubber layer (A) and the rubber layer (B) can be improved.
The fillers include carbon black and inorganic fillers.
The type of carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF, with HAF, ISAF, and SAF being preferred.
The inorganic filler includes metal oxides such as silica, alumina, titania, etc., and among these, silica is preferred.The type of silica is not particularly limited, and includes wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), colloidal silica, etc.In addition, when silica is contained as a filler, in order to improve the dispersibility of silica in the rubber layer (A) and the rubber layer (B), the rubber layer (A) and the rubber layer (B) may further include a silane coupling agent.

-Anti-aging agent-
The rubber layer (A) and the rubber layer (B) may contain an antioxidant, such as an amine-ketone compound, an imidazole compound, an amine compound, a phenol compound, a sulfur compound, and a phosphorus compound.

-Softener-
The rubber layer (A) and the rubber layer (B) may contain a softener. Examples of the softener include petroleum-based softeners such as process oil, lubricating oil, naphthenic oil, paraffin, liquid paraffin, petroleum asphalt, and vaseline, 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 alone or in combination of two or more.

- Crosslinking agent -
The rubber layer (A) and the rubber layer (B) may contain a crosslinking agent. The crosslinking agent is not particularly limited, and typically includes peroxides, sulfur, oximes, amines, ultraviolet curing agents, and the like.
Since the copolymer contains conjugated diene units, it can be crosslinked (vulcanized) with sulfur, such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, etc.

- Crosslinking accelerator -
The rubber layer (A) and the rubber layer (B) may contain a crosslinking accelerator. Examples of the crosslinking accelerator (vulcanization accelerator) include guanidine-based, sulfenamide-based, thiuram-based, thiazole-based, aldehyde amine-based, and thiocarbamate-based crosslinking accelerators.

(One embodiment)
Next, a laminate according to one embodiment of the present invention will be described with reference to FIG.
Fig. 1 is a cross-sectional view in the thickness direction, which is a schematic diagram of the laminate of this embodiment. The laminate 1 shown in Fig. 1 includes a rubber layer (A) 2 and a rubber layer (B) 3, and the rubber layer (A) 2 and the rubber layer (B) 3 are bonded together. Although the laminate 1 shown in Fig. 1 is composed of two layers, the rubber layer (A) 2 and the rubber layer (B) 3, the laminate of the present invention may be composed of three or more layers.

(Applications of the laminate)
The laminate of this embodiment can be applied to various rubber products including at least two rubber layers, in addition to the tires described below.

<Method of manufacturing laminate>
The laminate of the present embodiment described above can be manufactured by various methods. For example, (1) at least two cross-linked rubber layers may be laminated and heated, (2) at least one cross-linked rubber layer and at least one uncross-linked rubber layer may be laminated and heated, or (3) at least two uncross-linked rubber layers may be laminated and heated.

In one embodiment, the method for producing a laminate is characterized by laminating and heating at least two crosslinked rubber layers that include a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content of which is 3 to 40 parts by mass per 100 parts by mass of the rubber component. This method for producing a laminate provides a laminate with high interlayer peel strength with high productivity.

In another embodiment, a method for producing a laminate is characterized by laminating and heating at least one crosslinked rubber layer including a rubber component containing 50% or more by mass of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the content of the copolymer being 3 to 40 parts by mass per 100 parts by mass of the rubber component, and at least one uncrosslinked rubber layer including a rubber component containing 50% or more by mass of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the content of the copolymer being 3 to 40 parts by mass per 100 parts by mass of the rubber component. This method for producing a laminate also provides a laminate with high productivity and high interlayer peel strength. Here, at least one uncrosslinked rubber layer may be crosslinked (vulcanized) by heating. When the uncrosslinked rubber layer is crosslinked by heating, it is preferable that the uncrosslinked rubber layer contains the above-mentioned crosslinking agent and crosslinking accelerator.

In still another embodiment, the method for producing a laminate is characterized by laminating and heating (crosslinking) at least two uncrosslinked rubber layers, the rubber layers including a rubber component containing 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the content of the copolymer being 3 to 40 parts by mass per 100 parts by mass of the rubber component. This method for producing a laminate also provides a laminate with high productivity and high interlayer peel strength. Here, the at least two uncrosslinked rubber layers may be crosslinked (vulcanized) by heating. When the uncrosslinked rubber layer is crosslinked by heating, it is preferable that the uncrosslinked rubber layer contains the above-mentioned crosslinking agent and crosslinking accelerator.

The rubber layer (A) and the rubber layer (B) can be formed from a rubber composition containing a rubber component containing 50% by mass or more of the diene rubber and the copolymer having a conjugated diene unit and a non-conjugated olefin unit. In addition to the rubber component and the copolymer having a conjugated diene unit and a non-conjugated olefin unit, the rubber composition can contain the above-mentioned filler, silane coupling agent, antioxidant, softener, crosslinking agent, crosslinking accelerator, etc.
The rubber composition may be produced by mixing only the rubber component and the copolymer, or may be produced by mixing any additive component in addition to the rubber component and the copolymer.
Alternatively, the rubber component and the copolymer may be mixed alone or together with any other additive components using a mixer such as a single screw extrusion mixer, a twin screw extrusion mixer, a Banbury mixer, a roll or an internal mixer to produce the rubber component and the copolymer.
The components may be mixed in one step or in two or more steps.

When the components of the rubber composition are melt-kneaded in an extrusion kneader and the rubber composition is extruded, the extruded rubber composition may be directly cut into pellets, or strands may be formed and the strands may be cut into pellets using a pelletizer. The pellets may have any of the common shapes, such as cylinders, prisms, and spheres.

The rubber layer (A) and the rubber layer (B) may be produced by melt-kneading the rubber composition and then extruding the same, or by hot pressing the rubber composition.
The heat pressing temperature is preferably from 120 to 160°C, and more preferably from 130 to 150°C.

<Tires>
The tire of the present embodiment is characterized by including the laminate of the present embodiment described above. Since the tire of the present embodiment includes the laminate of the present embodiment described above, which has high interlayer peel strength and high productivity, the tire of the present embodiment is highly durable and also highly productive.

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 retread tire. Here, when one layer of the laminate described above corresponds to a tire repair patch, the other layer of the laminate corresponds to a damaged tire. Also, when one layer of the laminate described above corresponds to a tread rubber component of a retread tire, the other layer of the laminate corresponds to a base tire prepared by removing worn tread rubber from a tire.

The tire can be manufactured by a conventional method. For example, components that are normally used in tire manufacturing, such as a carcass layer made of an uncrosslinked rubber composition and/or cords, a belt layer, and tread rubber, are laminated in order onto a tire building drum, and the drum is removed to produce a green tire. The green tire is then crosslinked to manufacture the desired tire (e.g., a pneumatic tire).

In addition, if a tire is damaged, the damaged portion of the tire can be made into a rubber layer (B), and the rubber layer (A) can be laminated onto the rubber layer (B), and heated as desired to fix the rubber layer (A) to the rubber layer (B), thereby repairing the tire.

In addition, a retread tire can be manufactured by removing the tread rubber from a used tire to obtain a base tire, forming the outermost layer of the base tire as the rubber layer (B), and preparing a tread rubber member for retreading as the rubber layer (A), and laminating the rubber layer (A) on the rubber layer (B).

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

<Synthesis of copolymer having conjugated diene units and non-conjugated olefin units>
(Synthesis of Copolymer 1)
Into a thoroughly dried 2000 mL pressure-resistant stainless steel reactor, 75 g of styrene and 675 g of toluene were placed.
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-BnMe ₂ Si-3-Me]C ₉ H ₅ Gd[N(SiHMe ₂ ) ₂ ] ₂ }, 0.083 mmol of dimethylanilinium tetrakis(pentafluorophenyl)borate [Me ₂ NHPhB(C ₆ F ₅ ) ₄ ], and 0.35 mmol of diisobutylaluminum hydride were added to a glass container, and 30 g of toluene was further added to prepare a catalyst solution.
The obtained catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 60°C.
Next, ethylene was introduced into the pressure-resistant stainless steel reactor at a pressure of 1.5 MPa, and copolymerization was carried out for a total of 3 hours at 75° C. During the copolymerization, 80 g of a 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 solution of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) in isopropanol was added to the pressure-resistant stainless steel reactor to terminate the reaction.
Next, the copolymer was separated using a large amount of methanol and dried in vacuum at 50° C. to obtain Copolymer 1.

(Synthesis of Copolymer 2)
Into a thoroughly dried 2000 mL pressure-resistant stainless steel reactor, 30 g of styrene, 20 g of a toluene solution containing 5 g of 1,3-butadiene, and 430 g of toluene were placed.
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)Me ₂ Si] ₂ C ₉ H ₅ Gd[N(SiHMe ₂ ) ₂ ] ₂ }, 0.075 mmol of dimethylanilinium tetrakis(pentafluorophenyl)borate [Me ₂ NHPhB(C ₆ F ₅ ) ₄ ], and 0.35 mmol of diisobutylaluminum hydride were added to a glass container, and 20 mL of toluene was further added to prepare a catalyst solution.
The obtained catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 60°C.
Next, ethylene was introduced into the pressure-resistant stainless steel reactor at a pressure of 1.0 MPa, and copolymerization was carried out for a total of 3 hours at 75° C. During the 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 solution of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) in isopropanol was added to the pressure-resistant stainless steel reactor to terminate the reaction.
Next, the copolymer was separated using a large amount of methanol and dried in vacuum at 50° C. to obtain Copolymer 2.

<Method of measuring physical properties of copolymer>
The following physical properties of the synthesized copolymer were measured, and the results are shown in Table 1.

(1) Number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn)
Monodisperse polystyrene was analyzed by gel permeation chromatography [GPC: Tosoh HLC-8121GPC/HT, column: Tosoh GMH _HR -H(S)HT x 2, detector: differential refractometer (RI)]. As a standard, the number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) of the copolymer were determined in terms of polystyrene. The measurement temperature was 40°C.

(2) Contents of Butadiene Units, Ethylene Units, and Styrene Units The contents (mol %) of ethylene units, butadiene units, and styrene units in the copolymer were determined from the integral ratio of each peak in ¹ H-NMR spectrum (100° C., d-tetrachloroethane standard: 6 ppm).

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

(4) Content of 1,4-bonds in butadiene units 1,2-bonds and 3,4-bonds were determined by an infrared method (Morello method), and the content of 1,4-bonds was calculated by calculating the total amount of 1,2-bonds and 3,4-bonds from 100%.

(5) Glass transition temperature (Tg)
The glass transition temperature (Tg) of the copolymer was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000") in accordance with JIS K 7121-1987.

(6) Endothermic Peak Energy Using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000"), in accordance with JIS K 7121-1987, the obtained copolymer was heated from -150°C to 150°C at a rate of 10°C/min. Then, the endothermic peak energy (ΔH ₁ (J/g)) in the range of 0°C or more and less than 100°C and the endothermic peak energy (ΔH ₂ (J/g)) in the range of 100°C or more and 150°C or less at that time (1st run) were measured.

(7) Crystallinity The crystalline melting energy of 100% crystalline polyethylene and the melting peak energy of the resulting copolymer at 0 to 120° C. were measured, and the crystallinity was calculated from the energy ratio between the polyethylene and the copolymer. The melting peak energy was measured with a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000").

(8) Tensile strength (Tb) and elongation at break (Eb)
The specimen was molded into a dumbbell shape No. 3 based on JIS K 6251 (2017) to prepare a test specimen.
The tensile strength (Tb) was measured based on JIS K 6251 (2017) using a tensile testing device (manufactured by Instron) by elongating the test piece by 100% at 25°C, and the maximum tensile force required to break the test piece was measured.
The breaking elongation (Eb) was determined by measuring the length of a test piece at the time when the test piece broke after pulling the test piece at 25° C. at a rate of 100 mm/min, and expressing the length as a ratio to the length before pulling (100%).

(9) Confirmation of main chain structure ^{The 13} C-NMR spectrum of the synthesized copolymer was measured. Since no peak was observed at 10 to 24 ppm in the ¹³ C-NMR spectrum chart, it was confirmed that the main chain of the synthesized copolymer was composed only of acyclic structures.

<Preparation of Rubber Composition>
Rubber compositions were prepared by blending, kneading, and vulcanizing each component according to the compounding recipe shown in Table 2. The types and amounts of the blended copolymers having conjugated diene units and non-conjugated olefin units are as shown in Table 3.

*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

<Preparation and Evaluation of Laminate>
A rubber layer (A) and a rubber layer (B) were prepared from the rubber composition prepared as described above, and the rubber layer (A) and the rubber layer (B) were laminated and heated at 140° C. for 2 minutes to bond the rubber layer (A) and the rubber layer (B) to prepare a laminate. The peel strength of the obtained laminate was measured by the following method.

(10) Measurement of peel strength The rubber layer (B) was peeled off from the rubber layer (A) of the laminate, and the peel resistance (N/10 mm) was measured. The measurement results were expressed as an index, with the peel strength of the laminate of Example 1 taken as 100. The larger the index value, the higher the peel strength. The peel strength of each example was classified according to the following criteria.
Excellent: When the index value is 150 or more. Good: When the index value is less than 150 and 100 or more. Passable: When the index value is less than 100 and 50 or more. Poor: When the index value is less than 50. The results are shown in Table 3.

From Table 3, it can be seen that a laminate made from a rubber layer (A) containing a rubber component containing 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, and a rubber layer (B) containing a rubber component containing 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units has high peel strength between the rubber layer (A) and the rubber layer (B).

The laminate of this embodiment can be used for various rubber products such as tires.

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

Claims

A laminate comprising at least two rubber layers,
A laminate, characterized in that one rubber layer (A) in the laminate and another rubber layer (B) adjacent to the rubber layer (A) each contain 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 per 100 parts by mass of the rubber component.
The laminate according to claim 1, wherein the copolymer has a melting point of 50 to 120°C.
The laminate according to claim 1, wherein the copolymer has a content of the conjugated diene units of more than 0 mol% and not more than 50 mol%, and a content of the non-conjugated olefin units of 50 mol% or more and less than 100 mol%.
The laminate of claim 1, wherein the copolymer further contains aromatic vinyl units.
The laminate according to claim 4, wherein the copolymer has a conjugated diene unit content of 1 to 50 mol%, a non-conjugated olefin unit content of 40 to 97 mol%, and an aromatic vinyl unit content of 2 to 35 mol%.
The laminate according to claim 1, wherein the copolymer has a crystallinity of 0.5 to 50%.
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.
A method for manufacturing a laminate, comprising laminating and heating at least two crosslinked rubber layers that 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, the copolymer content of which is 3 to 40 parts by mass per 100 parts by mass of the rubber component.
A method for producing a laminate, comprising laminating and heating at least one cross-linked rubber layer, the rubber layer including a rubber component containing 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content being 3 to 40 parts by mass per 100 parts by mass of the rubber component, and at least one uncross-linked rubber layer, the rubber component including 50% by mass or more of a diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content being 3 to 40 parts by mass per 100 parts by mass of the rubber component.
A method for manufacturing a laminate, comprising laminating and heating at least two uncrosslinked rubber layers, the rubber layers including a rubber component containing 50% by mass or more of diene rubber and a copolymer having conjugated diene units and non-conjugated olefin units, the copolymer content of which is 3 to 40 parts by mass per 100 parts by mass of the rubber component.
A tire comprising the laminate described in claim 1.