Copolymer and method for decomposing copolymer

Abstract

The problem addressed by the present invention is to provide a polymer that is easy to decompose and a method for decomposing the polymer. This problem is solved by: a copolymer characterized by comprising an unsaturated hydrocarbon segment (A) and an enol ether segment (B), the content of the enol ether segment (B) being 0.005-40 mass% of the content of the unsaturated hydrocarbon segment (A); and a method for decomposing the copolymer, which is characterized by decomposing the copolymer in the presence of an acid.

Description

Technical Field

[0001] The present invention relates to copolymers and methods for decomposing copolymers. Background Art

[0002] Traditionally, rubber products are difficult to reuse, and after their product life, they are often reused as fuel, especially in cement plants, etc. However, in recent years, with the growing awareness of environmental issues, research has been conducted to reuse materials obtained by decomposing used rubber products instead of burning used rubber products as fuel. For example, as a method for decomposing vulcanized rubber, desulfurization using a solvent can be mentioned (see PTL 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] PTL 1: JP 2000-128901 A Summary of the invention

[0006] Problem that the invention aims to solve

[0007] Although vulcanized rubber can be decomposed by desulfurization using a solvent as described in PTL 1 and other documents, the decomposition conditions inevitably become severe. On the contrary, if the polymer (rubber component) as the main component of the rubber product is inherently easy to decompose, it becomes easier to decompose the used rubber product and reuse the obtained material.

[0008] Therefore, an object of the present invention is to provide an easily decomposable polymer.

[0009] Furthermore, another object of the present invention is to provide a method for decomposing such polymers.

[0010] Solutions for solving problems

[0011] The main features of the copolymer and the method for decomposing the copolymer of the present invention, which solve the above-mentioned problems, are as follows.

[0012] [1] A copolymer comprising:

[0013] Unsaturated hydrocarbon segment (A) and enol ether segment (B),

[0014] The content of the enol ether segment (B) is 0.005 to 40% by mass of the content of the unsaturated hydrocarbon segment (A).

[0015] [2] The copolymer according to [1], further comprising a cyclopentane skeleton segment (C).

[0016] [3] The copolymer according to [1] or [2], wherein the content of the enol ether segment (B) is 0.005 to 10% by mass of the content of the unsaturated hydrocarbon segment (A).

[0017] [4] A method for decomposing a copolymer, comprising decomposing the copolymer according to any one of [1] to [3] in the presence of an acid.

[0018] Effects of the Invention

[0019] According to the present invention, an easily decomposable polymer can be provided.

[0020] According to the present invention, a method for decomposing such a polymer can also be provided. DETAILED DESCRIPTION

[0021] The copolymer and the method for decomposing the copolymer according to the present invention will be illustrated in detail with reference to one embodiment.

[0022] <Definition>

[0023] The compounds described in this specification may be partially or completely derived from fossil resources, biological resources such as plant resources, or renewable resources such as used tires. Alternatively, they may be derived from a mixture of two or more of fossil resources, biological resources and renewable resources.

[0024] <Copolymer>

[0025] The copolymer of the present embodiment comprises an unsaturated hydrocarbon segment (A) and an enol ether segment (B). In the copolymer of the present embodiment, the content of the enol ether segment (B) is 0.005 to 40% by mass of the content of the unsaturated hydrocarbon segment (A).

[0026] The copolymer of the present embodiment comprises an unsaturated hydrocarbon segment (A), wherein the unsaturated hydrocarbon segment (A) exhibits viscoelastic behavior and imparts elastomeric properties to the copolymer itself and a composition comprising the copolymer.

[0027] Furthermore, the copolymer of the present embodiment contains the enol ether segment (B), wherein the enol ether segment (B) serves as a decomposition point, enabling decomposition of the copolymer itself and a composition containing the copolymer.

[0028] Furthermore, in the copolymer of the present embodiment, since the content of the enol ether segment (B) is 0.005 mass % or more of the content of the unsaturated hydrocarbon segment (A), the copolymer itself and the composition containing the copolymer are easily decomposed.

[0029] Therefore, the copolymer of the present embodiment is easily decomposed, and in particular, as described later, it is easily decomposed in the presence of an acid.

[0030] Furthermore, the copolymer of the present embodiment has a content of the enol ether segment (B) of 40% by mass or less of the content of the unsaturated hydrocarbon segment (A), thereby having sufficient elastomer properties and being suitably used for various rubber products such as tires, rubber tracks, and seismic isolation rubbers.

[0031] -Unsaturated hydrocarbon segment (A)-

[0032] The copolymer of the present embodiment comprises an unsaturated hydrocarbon segment (A).

[0033] The unsaturated hydrocarbon segment (A) is a segment having an unsaturated bond in the main chain, and wherein the main chain is a hydrocarbon. It should be noted that the unsaturated hydrocarbon segment (A) may have a substituent other than a hydrocarbon group in the side chain. Here, examples of hydrocarbon groups that may be bonded to the side chain include alkyl groups, and examples of substituents other than hydrocarbon groups that may be bonded to the side chain include halogen groups. Examples of unsaturated bonds in the main chain include carbon-carbon double bonds and carbon-carbon triple bonds, wherein carbon-carbon double bonds are preferred.

[0034] The unsaturated hydrocarbon segment (A) may be a segment (monomer unit) derived from various monomers, and the monomer may be a chain monomer or a cyclic monomer.

[0035] In one embodiment, the unsaturated hydrocarbon segment (A) is preferably a segment (monomer unit) derived from a cyclic unsaturated hydrocarbon compound (A1) having 4 to 12 carbon atoms and having one or two carbon-carbon double bonds as a monomer.

[0036] The cyclic unsaturated hydrocarbon compound (A1) is preferably a compound having a 6- to 10-membered ring. In addition, the cyclic unsaturated hydrocarbon compound (A1) preferably has 6 to 10 carbons. In addition, the cyclic unsaturated hydrocarbon compound (A1) preferably has two carbon-carbon double bonds. In these cases, the reactivity in the ring-opening polymerization of the cyclic unsaturated hydrocarbon compound (A1) is improved.

[0037] Examples of the cyclic unsaturated hydrocarbon compound (A1) include cyclooctadiene compounds represented by the following general formula (1):

[0038] [Chemical formula 1]

[0039]

[0040] In the formula, R 1 are each independently a halogen atom or an alkyl group, and n 1 is an integer of 0 to 12. Here, examples of the halogen atom include fluorine, chlorine and bromine. In addition, the alkyl group is preferably an alkyl group having 1 to 5 carbon atoms, and examples thereof include, for example, a methyl group, an ethyl group, an n-propyl group and an isopropyl group.

[0041] In the general formula (1), R 1is a substituent on the cyclooctadiene ring and can replace any hydrogen atom bonded to the cyclooctadiene ring, and n 1 Represents a substituent R 1 The number of

[0042] As the cyclooctadiene compound of the general formula (1), a commercially available compound may be used, or a compound synthesized according to a known method may be used. 1 is 0 or an integer from 1 to 12, wherein R 1 Compounds containing a halogen atom, a methyl group or an ethyl group are preferred, wherein R 1 Compounds which are methyl groups are more preferred. Specific examples of the cyclooctadiene compounds of the general formula (1) include 1,5-cyclooctadiene, 1-chloro-1,5-cyclooctadiene, 1,5-dichloro-1,5-cyclooctadiene, 1-methyl-1,5-cyclooctadiene and 1,5-dimethyl-1,5-cyclooctadiene.

[0043] The cyclic unsaturated hydrocarbon compound (A1) can be introduced into the copolymer by means of ring-opening polymerization (preferably by ring-opening metathesis polymerization) to form the unsaturated hydrocarbon segment (A).

[0044] In addition, the cyclooctadiene compound represented by the above general formula (1) can be introduced into the copolymer by ring-opening metathesis polymerization to form a butadiene segment. Here, the butadiene segment refers to a segment (monomer unit) formed when 1,3-butadiene is introduced into the polymer via a 1,4-bond, wherein the bonding mode of carbon atoms constituting the main chain is represented by -CC=CC-, and various substituents can be bonded to the carbon atoms constituting the main chain.

[0045] In one embodiment, the unsaturated hydrocarbon segment (A) may be a segment (monomer unit) derived from a chain unsaturated hydrocarbon compound (A2) having 4 to 12 carbon atoms and one or two carbon-carbon double bonds as a monomer. Examples of such chain unsaturated hydrocarbon compounds (A2) include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene.

[0046] The chain unsaturated hydrocarbon compound (A2) can form the unsaturated hydrocarbon segment (A) by being introduced into the copolymer by addition polymerization.

[0047] The ratio of the unsaturated hydrocarbon segment (A) in the copolymer of the present embodiment is preferably in the range of 60 to 99.995 mass %, more preferably in the range of 90 to 99.995 mass %, even more preferably in the range of 95 to 99.995 mass %, and particularly preferably in the range of 97 to 99.995 mass %. When the ratio of the unsaturated hydrocarbon segment (A) in the copolymer is 60 mass % or more, the copolymer exhibits sufficient elastomer properties and can be suitably used for rubber products.

[0048] - Enol ether segment (B) -

[0049] The copolymer of this embodiment has an enol ether segment (B).

[0050] The enol ether segment (B) is a segment having an enol ether moiety (-C=CO-) in the main chain. The enol ether moiety is easily hydrolyzed by acid or the like, and when the copolymer has an enol ether moiety in the main chain, the main chain of the copolymer becomes more easily broken, making it more easily decomposed.

[0051] The enol ether segment (B) may be a segment (monomer unit) derived from various monomers, and the monomer may be a chain monomer or a cyclic monomer.

[0052] In one embodiment, the enol ether segment (B) is preferably a segment (monomer unit) derived from an unsaturated heterocyclic compound (B1) as a monomer, containing oxygen in the main chain of the ring and having one or two carbon-carbon double bonds. Here, "containing oxygen in the main chain of the ring" means that one or more of the constituent atoms (members) of the ring is oxygen. Examples of such unsaturated heterocyclic compounds (B1) include dihydrofuran compounds (cyclic enol ether compounds) represented by the following general formula (2):

[0053] [Chemical formula 2]

[0054]

[0055] In the formula, R 2 are each independently a halogen atom or an alkyl group, and n 2 is an integer of 0 to 6. Here, examples of the halogen atom include fluorine, chlorine and bromine. In addition, the alkyl group is preferably an alkyl group having 1 to 5 carbon atoms, and examples thereof include, for example, a methyl group, an ethyl group, an n-propyl group and an isopropyl group.

[0056] In the general formula (2), R 2 is a substituent on the dihydrofuran ring and can replace any hydrogen atom bonded to the dihydrofuran ring, and n 2 Represents a substituent R 2 The number of

[0057] As the dihydrofuran compound of the general formula (2), a commercially available compound may be used, or a compound synthesized according to a known method may be used. From the viewpoint of easy availability, etc., when n 2 0 or n 2 is an integer from 1 to 6, wherein R 2 Compounds in which R is a halogen atom, a methyl group or an ethyl group are preferred, and in which R 2 Compounds which are methyl groups are more preferred. Examples of the dihydrofuran compound of the general formula (2) include 2,3-dihydrofuran and 5-methyl-2,3-dihydrofuran.

[0058] The unsaturated heterocyclic compound (B1) can be introduced into the copolymer by means of ring-opening polymerization (preferably ring-opening metathesis polymerization) to form the enol ether segment (B).

[0059] The content of the enol ether segment (B) is 0.005 to 40% by mass of the content of the unsaturated hydrocarbon segment (A), preferably 0.005 to 10% by mass, more preferably 0.005 to 5% by mass, and even more preferably 0.005 to 3% by mass. When the content of the enol ether segment (B) is 0.005% by mass or more of the content of the unsaturated hydrocarbon segment (A), the copolymer itself and the composition containing the copolymer become easier to decompose. In addition, when the content of the enol ether segment (B) is 40% by mass or less of the content of the unsaturated hydrocarbon segment (A), the copolymer exhibits sufficient elastomer properties and can be suitable for use in rubber products. In addition, when the content of the enol ether segment (B) is 0.005 to 10% by mass of the content of the unsaturated hydrocarbon segment (A), the ease of decomposition of the copolymer and the elastomer properties of the copolymer can be balanced at a high level.

[0060] The proportion of the enol ether segment (B) in the copolymer of the present embodiment is preferably in the range of 0.005 to 40% by mass, more preferably in the range of 0.005 to 10% by mass, even more preferably in the range of 0.005 to 5% by mass, and particularly preferably in the range of 0.005 to 3% by mass. When the proportion of the enol ether segment (B) in the copolymer is 0.005% by mass or more, the copolymer itself and the composition containing the copolymer become easy to decompose. In addition, when the proportion of the enol ether segment (B) in the copolymer is 40% by mass or less, the copolymer exhibits sufficient elastomeric properties and can be suitable for use in rubber products.

[0061] -Cyclopentane backbone segment (C)-

[0062] The copolymer of this embodiment preferably further comprises a cyclopentane skeleton segment (C). A copolymer having a cyclopentane skeleton segment (C) is easy to synthesize.

[0063] The cyclopentane skeleton segment (C) is a segment containing a cyclopentane ring in the main chain. Various substituents may be bonded to the cyclopentane ring, and examples of such substituents include a halogen group, an alkyl group, and an alkylene group.

[0064] The cyclopentane skeleton segment (C) may be a segment (monomer unit) derived from various monomers. In one embodiment, the cyclopentane skeleton segment (C) is preferably a segment (monomer unit) derived from a compound (C1) having a norbornene skeleton as a monomer. Examples of such compounds (C1) having a norbornene skeleton include norbornene compounds represented by the following general formula (3):

[0065] [Chemical formula 3]

[0066]

[0067] In the formula, R 3 Each independently represents a halogen atom, an alkyl group or an alkenyl group, and the two R 3 The groups may together form an alkylene group, and n 3 is an integer from 0 to 10. Here, examples of the halogen atom include fluorine, chlorine and bromine. In addition, the alkyl group is preferably an alkyl group having 1 to 5 carbon atoms, and examples thereof include, for example, methyl, ethyl, n-propyl and isopropyl. In addition, the alkenyl group is preferably an alkenyl group having 2 to 5 carbon atoms, and examples thereof include, for example, vinyl and allyl. In addition, two R bonded to the same carbon atom are preferably 3 Examples of the alkylene group formed by the group include a methylene group (=CH2) and an ethylene group (=CH-CH3).

[0068] In the general formula (3), R 3 is a substituent on the norbornene ring and can replace any hydrogen atom bonded to the norbornene ring, and n 3 Represents a substituent R 3 The number of

[0069] As the norbornene compound of the general formula (3), a commercially available compound may be used, or a compound synthesized according to a known method may be used. From the viewpoint of ease of availability, etc., when n 3 0 or n 3 is an integer from 1 to 10, wherein R 3 A compound wherein two R 3 Compounds in which the group forms an ethylene group are preferred. Examples of the norbornene compound of the general formula (3) include norbornene, 5-methyl-2-norbornene, 5-vinyl-2-norbornene and 5-ethylidene-2-norbornene.

[0070] The compound (C1) having a norbornene skeleton can be introduced into the copolymer by ring-opening polymerization (preferably by ring-opening metathesis polymerization) to form a cyclopentane skeleton segment (C).

[0071] When the copolymer of the present embodiment has a cyclopentane skeleton segment (C), the content of the cyclopentane skeleton segment (C) is preferably 0.005 to 40% by mass of the content of the unsaturated hydrocarbon segment (A), more preferably 0.005 to 10% by mass, even more preferably 0.005 to 5% by mass, and particularly preferably 0.005 to 3% by mass. The copolymer having a content of cyclopentane skeleton segment (C) of 0.005% by mass or more of the content of the unsaturated hydrocarbon segment (A) is easily synthesized. In addition, when the content of the cyclopentane skeleton segment (C) is 40% by mass or less of the content of the unsaturated hydrocarbon segment (A), the copolymer has sufficient elastomer properties and can be suitable for use in rubber products. In addition, when the content of the cyclopentane skeleton segment (C) is 0.005 to 10% by mass of the content of the unsaturated hydrocarbon segment (A), the ease of synthesis of the copolymer and the elastomer properties of the copolymer can be balanced at a high level.

[0072] When the copolymer of the present embodiment has a cyclopentane skeleton segment (C), the proportion of the cyclopentane skeleton segment (C) in the copolymer is preferably in the range of 0.005 to 40% by mass, more preferably in the range of 0.005 to 10% by mass, even more preferably in the range of 0.005 to 5% by mass, and particularly preferably in the range of 0.005 to 3% by mass. Copolymers having a cyclopentane skeleton segment (C) ratio of 0.005% by mass or more are easy to synthesize. In addition, when the proportion of the cyclopentane skeleton segment (C) in the copolymer is 40% by mass or less, the copolymer has sufficient elastomer properties and can be suitable for use in rubber products.

[0073] -Other segments (D)-

[0074] The copolymer of this embodiment may further include other segments (D).

[0075] When the copolymer of the present embodiment contains other segments (D), the proportion of the other segments (D) in the copolymer is preferably in the range of 0.005 to 40% by mass, more preferably in the range of 0.005 to 10% by mass, even more preferably in the range of 0.005 to 5% by mass, and particularly preferably in the range of 0.005 to 3% by mass.

[0076] The ratios of the unsaturated hydrocarbon segment (A), the enol ether segment (B), the cyclopentane skeleton segment (C) and the other segment (D) in the copolymer of this embodiment can be calculated from (1) 1The integrated ratio of each peak in the H-NMR spectrum and the amount of each monomer used in the production of the (2) copolymer and the amount of each unreacted monomer are calculated. From the calculated ratios, the mass ratio of each content can be calculated.

[0077] -Molecular weight of copolymer-

[0078] The number average molecular weight (Mn) of the copolymer of the present embodiment is preferably 10,000 to 2,000,000, and more preferably 20,000 to 1,000,000. When the number average molecular weight (Mn) is 10,000 or more, the copolymer can be suitably used for various rubber products such as tires, rubber tracks, and seismic isolation rubbers, and when the number average molecular weight (Mn) is 2,000,000 or less, it is easy to mix with various compounding agents for rubber products.

[0079] The weight average molecular weight (Mw) of the copolymer of the present embodiment is preferably 20,000 to 4,000,000, and more preferably 40,000 to 2,000,000. When the weight average molecular weight (Mw) is 20,000 or more, the copolymer can be suitably used in various rubber products such as tires, rubber tracks, and seismic isolation rubbers, and when the weight average molecular weight (Mw) is 4,000,000 or less, it is easy to mix with various compounding agents for rubber products.

[0080] In the present specification, the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the copolymer are determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0081] -Method for producing copolymer-

[0082] The copolymer of the present embodiment can be manufactured by ring-opening polymerization of a cyclic unsaturated hydrocarbon compound (A1) having 4 to 12 carbons and having one or two carbon-carbon double bonds as a monomer and a cyclic unsaturated heterocyclic compound (B1) containing oxygen in the main chain of the ring and having one or two carbon-carbon double bonds, but is not particularly limited thereto. For example, the copolymer of the present embodiment can be formed by ring-opening polymerization (preferably by ring-opening metathesis polymerization) of a cyclooctadiene compound represented by the above-mentioned general formula (1) and a dihydrofuran compound represented by the above-mentioned general formula (2). As an example, the reaction formula of ring-opening metathesis polymerization is described below, wherein 1,5-cyclooctadiene is used as the compound represented by the general formula (1) and 2,3-dihydrofuran is used as the compound represented by the general formula (2).

[0083] [Chemical formula 4]

[0084]

[0085] In addition, when the copolymer of the present embodiment has a cyclopentane skeleton segment (C), it can be produced by ring-opening polymerization of a cyclic unsaturated hydrocarbon compound (A1) having 4 to 12 carbon atoms and having one or two carbon-carbon double bonds, a cyclic unsaturated heterocyclic compound (B1) containing oxygen in the main chain of the ring and having one or two carbon-carbon double bonds, and a compound (C1) having a norbornene skeleton as monomers, but is not particularly limited thereto. For example, when the copolymer has a cyclopentane skeleton segment (C), it can be formed by ring-opening polymerization (preferably by ring-opening metathesis polymerization) of a cyclooctadiene compound represented by the above-mentioned general formula (1), a dihydrofuran compound represented by the above-mentioned general formula (2), and a norbornene compound represented by the above-mentioned general formula (3). As an example, a reaction formula of ring-opening metathesis polymerization is described below, in which 1,5-cyclooctadiene is used as the compound represented by the general formula (1), 2,3-dihydrofuran is used as the compound represented by the general formula (2), and 5-ethylidene-2-norbornene is used as the compound represented by the general formula (3).

[0086] [Chemical formula 5]

[0087]

[0088] In the above-mentioned ring-opening polymerization, a known catalyst can be used.

[0089] In addition, in the above-mentioned ring-opening metathesis polymerization, known catalysts can be used, for example, transition metal complexes such as titanium complexes, zirconium complexes, molybdenum complexes, ruthenium complexes, tantalum complexes, tungsten complexes and rhenium complexes can be used. Among them, transition metal-carbene complexes such as Grubbs first generation catalyst, Grubbs second generation catalyst and Hoveyda-Grubbs catalyst are preferred. It should be noted that the Grubbs second generation catalyst is represented by the following structural formula:

[0090] [Chemical formula 6]

[0091]

[0092] And commercially available products can be used.

[0093] The amount of the catalyst used is, for example, preferably 0.00001 to 0.1 mol, more preferably 0.0001 to 0.01 mol, and particularly preferably 0.0001 to 0.001 mol relative to 1 mol of the raw material monomer.

[0094] In the above ring-opening polymerization, the reaction temperature is preferably -50°C to 200°C, and more preferably 0°C to 200°C. The reaction time is preferably 1 to 24 hours, and more preferably 1 to 6 hours. The reaction pressure may be pressurized, reduced pressure or atmospheric pressure, but atmospheric pressure is preferred. The reaction atmosphere is preferably an inert gas atmosphere such as nitrogen or argon. The ring-opening polymerization may be carried out in a batchwise manner or a continuous process.

[0095] The above-mentioned ring-opening polymerization can be carried out in a solvent. For example, as the solvent, a solvent inactive to the reaction is preferred, such as an aliphatic halogenated solvent, for example, dichloromethane, chloroform and 1,2-dichloroethane; an ether solvent, for example, diethyl ether, tetrahydrofuran and dioxane; an aromatic hydrocarbon solvent, for example, benzene, toluene, xylene and mesitylene; an aromatic halogenated solvent, for example, monochlorobenzene and dichlorobenzene; and an aliphatic hydrocarbon solvent, for example, hexane, heptane, octane and cyclohexane.

[0096] -Application of copolymers-

[0097] The copolymer of this embodiment can be used for various rubber products. For example, the rubber products include tires, rubber tracks and vibration-isolating rubbers.

[0098] In the case of using in these rubber products, the copolymer can be mixed with various compounding agents according to the desired properties to thereby form a rubber composition. In addition, the copolymer can be compounded with other rubber components if necessary.

[0099] Examples of other rubber components include natural rubber (NR), synthetic diene rubber and non-diene rubber. Examples of synthetic diene rubber include synthetic isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), styrene-isoprene rubber (SIR), chloroprene rubber (CR), ethylene-butadiene copolymer and ethylene-styrene-butadiene copolymer. Examples of non-diene rubber include silicone rubber, fluororubber and polyurethane rubber.

[0100] Examples of the compounding agent include fillers (eg, carbon black and silica), softeners, waxes, stearic acid, antioxidants, silane coupling agents, zinc white (zinc oxide), and vulcanization accelerators.

[0101] As described above, since the copolymer of the present embodiment is easily decomposed, the rubber composition containing the copolymer of the present embodiment and other rubber components and compounding agents is also easily decomposed. In addition, the rubber products manufactured by such rubber compositions are easily decomposed and reused after use.

[0102] <Method for Decomposing Copolymer>

[0103] The method for decomposing the copolymer of the present embodiment includes decomposing the copolymer of the present embodiment in the presence of an acid. The copolymer of the present embodiment described above is easily decomposed, and, in particular, is easily hydrolyzed in the presence of an acid. Therefore, according to the method for decomposing the copolymer of the present embodiment, the copolymer can be easily decomposed.

[0104] The materials obtained by the copolymer decomposition method of the present embodiment can be reused for various purposes. For example, they can be used as a raw material for producing a copolymer or as a synthetic raw material for other chemical substances.

[0105] The acid can be an inorganic acid or an organic acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid and nitric acid. Examples of organic acids include formic acid, acetic acid and propionic acid. Among them, hydrochloric acid is preferred as the acid. When hydrochloric acid is used as the acid, the copolymer is easily decomposed and the waste liquid is also easily handled.

[0106] The decomposition temperature in the presence of an acid is not particularly limited, but a range of 0°C to 100°C is preferred, and a temperature near room temperature, such as 15°C to 30°C, may also be used. In addition, the decomposition time in the presence of an acid is not particularly limited and may be appropriately selected depending on the above-mentioned decomposition temperature and various properties of the copolymer. However, a range of 1 to 24 hours is preferred, and 1 to 6 hours is more preferred. In addition, the reaction pressure during decomposition may be pressurized, decompressed, or atmospheric pressure, but atmospheric pressure is preferred. The reaction atmosphere is not particularly limited, and may be under air or under an inert gas atmosphere such as nitrogen or argon.

[0107] The decomposition in the presence of an acid is preferably carried out in a solvent. For example, the solvent to be used is preferably a solvent in which the acid used is easily soluble, such as water or alcohol. Among them, water is preferred as a solvent. Water has excellent solubility for acids, and waste liquid is also easy to handle.

[0108] Example

[0109] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[0110] <Analysis Method of Polymer>

[0111] (1) Analysis method of the ratio of each segment in the polymer

[0112] The proportions of the segments derived from 1,5-cyclooctadiene, 2,3-dihydrofuran and 5-ethylidene-2-norbornene in the polymer are based on 1 It was determined by the integration ratio of each peak in the H-NMR (room temperature, in CDCl3 solvent) spectrum.

[0113] The calculation is performed as follows.

[0114] The integrated value of the peak at 5.8 to 6.4 ppm is defined as I1 (derived from hydrogen at position "a" in the following structural formula),

[0115] The integrated value of the peak at 5.0 to 5.7 ppm is defined as I2 (derived from hydrogen at positions "b", "c" and "d" in the following structural formula), and

[0116] The integrated value of the peak at 2.4 to 2.6 ppm is defined as I3 (derived from hydrogen at position "e" in the following structural formula).

[0117] [Chemical formula 7]

[0118]

[0119] Then, the following calculations were performed: x=I1 / 1, y=I3 / 1 and z=(I2-(3y)) / 4. Using the obtained values ​​of x, y and z, the content of the segment was found as follows.

[0120] Content of segments derived from 2,3-dihydrofuran (mol%) = x / (x+y+z)

[0121] Content of the segment derived from 5-ethylidene-2-norbornene (mol%) = y / (x+y+z)

[0122] Content of the segment derived from 1,5-cyclooctadiene (mol%) = z / (x+y+z)

[0123] In addition, each ratio (mass %) of the segment derived from 2,3-dihydrofuran, 5-ethylidene-2-norbornene, and 1,5-cyclooctadiene was obtained by converting the corresponding value in "mol %" into a value in "mass %".

[0124] No measurements were performed on the polymer in Example 1. However, based on the amounts of the raw materials used and the yields, the polymer in Example 1 is believed to have the same composition as the polymer in Example 4.

[0125] (2) Analysis method of polymer molecular weight

[0126] The number average molecular weight (Mn), weight average molecular weight (Mw), peak top molecular weight (Mp) and molecular weight distribution (Mw / Mn) of the polymer (in terms of polystyrene) were determined by gel permeation chromatography [GPC: HLC-8321GPC / HT manufactured by Tosoh Corporation, column: two HT-806M columns manufactured by Showa Denko KK, detector: differential refractometer (RI)] using monodisperse polystyrene as a reference. Note that the measurement temperature was 40°C.

[0127] <Method for Synthesizing Copolymer>

[0128] (Example 1)

[0129] In a glass container replaced with nitrogen, 11.20 g (103.5 mmol) of 1,5-cyclooctadiene, 0.06 g (0.86 mmol) of 2,3-dihydrofuran and 0.60 g (4.99 mmol) of 5-ethylidene-2-norbornene were added. After the container was sealed and purged with nitrogen for 5 minutes, 40 g of dehydrated tetrahydrofuran was added.

[0130] Next, 2 mL of a 0.00718 M Ru catalyst (Grubbs second generation catalyst) in toluene solution was added to the container. The polymerization reaction was carried out at room temperature for 180 minutes.

[0131] Then, an excess of ethyl vinyl ether was added to the container and stirred for 30 minutes to quench the reaction. Thereafter, the contents of the container were poured into a large amount of isopropanol solution containing BHT (2,6-di-tert-butyl-4-methylphenol) to precipitate the polymer. The polymer was filtered and dried under reduced pressure at 60° C. for 5 hours to obtain 10.4 g of the polymer.

[0132] (Examples 2 to 5 and Comparative Examples 1 to 2)

[0133] A polymer was obtained in a similar manner to Example 1 by setting the amount of 2,3-dihydrofuran used, the amount of 5-ethylidene-2-norbornene used, the molar concentration of the Ru catalyst in the toluene solution of the Ru catalyst, the amount of the toluene solution of the Ru catalyst used, and the polymerization time to the conditions summarized in Table 1. The amount and yield of the obtained polymer are summarized in Table 1.

[0134] <Method for Decomposing Copolymer>

[0135] The solution was prepared by dissolving 10 mg of polymer in 5 mL of dehydrated tetrahydrofuran (THF). Two drops of 1 N HCl solution were added to the solution, and the decomposition reaction was carried out at room temperature for the reaction time summarized in Table 1. The molecular weight before the decomposition reaction and the molecular weight after the decomposition reaction were analyzed using GPC to confirm the degree of reduction of the molecular weight. The results are summarized in Table 1.

[0136] [Table 1]

[0137]

[0138] As can be seen from Table 1, the copolymers according to Examples of the present invention undergo decomposition in the presence of an acid, and their molecular weights are significantly reduced.

[0139] On the other hand, as can be seen from the results of Comparative Examples 1 and 2, the (co)polymer having no enol ether segment (B) does not undergo a decrease in molecular weight even when treated in the presence of an acid and is difficult to decompose.

[0140] Industrial Applicability

[0141] The copolymer of the present invention can be used for various rubber products such as tires, rubber tracks and vibration-isolating rubbers.

Claims

1. A copolymer, characterized in that Include: Unsaturated hydrocarbon segment (A) and enol ether segment (B), The content of the enol ether segment (B) is 0.005 to 40% by mass of the content of the unsaturated hydrocarbon segment (A). 2 . The copolymer according to claim 1 , further comprising a cyclopentane backbone segment (C). 3 . The copolymer according to claim 1 , wherein the content of the enol ether segment (B) is 0.005 to 10% by mass of the content of the unsaturated hydrocarbon segment (A).

4. A method for decomposing a copolymer, characterized in that: The copolymer according to any one of claims 1 to 3 is decomposed in the presence of an acid.

Images