Method for decomposing polymer compound and composition therefor

Abstract

To provide a method for decomposing a polymer compound having a partial structure represented by general formula (1), the method enabling utilization of an oxidizing agent having relatively weak oxidizing action and allowing oxidation of a sulfide portion and subsequent decomposition by a base to proceed in the same solution.SOLUTION: The present invention provides a method that comprises applying an oxidizing agent to a polymer compound having a partial structure represented by general formula (1) under a basic condition in the coexistence of a catalyst to decompose the polymer compound, wherein the catalyst is at least one selected from the group consisting of compounds composed of oxoacids or salts thereof of vanadium, niobium, tantalum, chromium, molybdenum or tungsten, and heteropoly acids or salts thereof produced through condensation of such oxoacids with oxoacids of hetero atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for decomposing polymeric compounds and a composition therefor. [Background technology]

[0002] In recent years, from the viewpoint of environmental protection, etc., there has been active development of degradable polymer materials, such as biodegradable polymers and photodegradable polymers, which are naturally decomposed when discarded. However, biodegradable polymers and photodegradable polymers have the problem of deteriorating over time in normal usage environments.

[0003] For this reason, there is a demand for polymers that do not deteriorate over time during use and can be quickly decomposed when disposed of. Several examples of polymer compounds that can be easily decomposed with an oxidizing agent when disposed of have been proposed, including poly(diacylhydrazines) obtained by polycondensing dicarboxylic acids or their reactive derivatives (acid chlorides or active ester derivatives) with hydrazine or dihydrazides of dicarboxylic acids (see, for example, Patent Documents 1 and 2).

[0004] Patent Document 3 discloses a polymer compound having a partial structure represented by the following general formula (1): This polymer compound has a sulfide (sulfur atom) present as shown in general formula (1). A carbon atom at the β-position of the sulfide is bonded to a carbonyloxy group that can form a stable anion and become a leaving group. When this sulfide is oxidized with an oxidizing agent and then treated with a base, the carbonyloxy group becomes an anion under the action of the base and is eliminated from the β-carbon, as shown in (A) to (D) or (A') to (D') in the following chemical reaction formula, thereby scission of the polymer chain. [ka] [ka]

[0005] Specifically, the partial structure represented by the general formula (1) is first oxidized by an oxidizing agent, converting the sulfide moiety to sulfone as shown in (B). This is also true for (A') → (B') shown in the lower part. Then, as the sulfide is converted to sulfone through this oxidation, the electron density at the α-carbon of the sulfone decreases, increasing the acidity of the hydrogen atom attached to this carbon. If a base is present nearby, the hydrogen atom at the α-carbon is protonated, resulting in intermediate (C), a carbanion. In intermediate (C), if a carbonyloxy group, which can exist stably as an anion, is attached to the β-carbon, this carbonyloxy group becomes a carboxylate anion, resulting in intramolecular cleavage as shown in (D). In other words, a polymer compound having the partial structure of the general formula (1) undergoes a series of reactions shown in (A) to (D), resulting in a lower molecular weight suitable for reuse or disposal as a compound. Note that the lower parts (A') to (D') also undergo a similar reaction mechanism for lowering the molecular weight. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-022315 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-052075 [Patent Document 3] International Publication WO2024 / 004741 A1 Summary of the Invention [Problem to be solved by the invention]

[0007] The polymer described in Patent Document 3 can be decomposed by the action of an oxidizing agent under basic conditions, as described above. However, in practice, because weak oxidizing agents are difficult to induce such oxidation, a strong oxidizing agent, such as persulfate, must be used. However, this oxidizing agent oxidizes the base, hindering the reaction. For this reason, the oxidation step using an oxidizing agent (reaction step (A) → (B) in the above chemical reaction formula) and the decomposition step under basic conditions (reaction step (B) → (D) in the above chemical reaction formula) must be carried out in separate solutions, making it difficult to decompose this polymer using a single solution. Furthermore, when carrying out decomposition in two steps like this, only the surface of the plastic product made of the polymer is oxidized in the first oxidation step, and only this oxidized surface is decomposed in the subsequent decomposition step. This necessitates repeated oxidation and decomposition steps in separate solutions, which is extremely cumbersome.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a method for decomposing a polymer compound having a partial structure represented by the above general formula (1), which can use an oxidizing agent with a relatively weak oxidizing action, and which can cause the oxidation of the sulfide moiety and the subsequent decomposition by a base to proceed in the same solution. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems and have found that when a polymeric compound having the partial structure represented by general formula (1) is decomposed using an oxidizing agent and a base, sulfides can be oxidized even with weak oxidizing agents such as hydrogen peroxide and organic peroxides, which are difficult to oxidize under basic conditions, by using as a catalyst at least one selected from the group consisting of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten oxoacids or their salts, and heteropolyacids or their salts formed by condensation of such oxoacids with oxoacids of heteroatoms. Furthermore, the use of such a weak oxidizing agent prevents the action of the base compound from being inhibited by the oxidizing agent, thereby enabling a one-component process in which the oxidizing agent and the base compound coexist in the same solution. Furthermore, this one-component process allows the oxidation process on the surface of a plastic product made of the polymer and the decomposition process under basic conditions to be carried out simultaneously in the same solution, which is far more efficient than the above-mentioned oxidation process and decomposition process performed alternately in separate solutions. Specifically, the present invention provides the following:

[0010] (1) The present invention is a method for decomposing a polymer compound having a partial structure represented by the following general formula (1), characterized in that an oxidizing agent is allowed to act on the polymer compound in the presence of a catalyst under basic conditions, and the catalyst is at least one selected from the group consisting of an oxoacid of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten, or a salt thereof, and a heteropolyacid or a salt thereof obtained by condensation of such an oxoacid with an oxoacid of a heteroatom: [ka] (In the above general formula (1), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group which may have a substituent, or a single bond which bonds to an atom outside of general formula (1), and a single bond marked with a wavy line represents a bond to an atom outside of general formula (1).)

[0011] (2) The present invention also provides the method according to (1), wherein the amount of the catalyst is 0.001 to 0.5 equivalents relative to the number of partial structures represented by general formula (1) contained in the polymer compound.

[0012] (3) The present invention also relates to the method according to (1) or (2), wherein the oxidizing agent is hydrogen peroxide or an organic peroxide.

[0013] (4) The present invention also provides the method according to (3), wherein the decomposition is carried out in an aqueous solvent.

[0014] (5) The present invention also relates to the method according to any one of (1) to (4), wherein the polymer compound has a repeating unit represented by the following general formula (2a) or general formula (2b): [ka] In the above general formula (2a), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and X is a divalent group. In the above general formula (2b), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and R 1 is an alkyl group having 1 to 10 carbon atoms which may have a substituent or an aryl group which may have a substituent, or R 1 and one R may be bonded to each other to form a cyclic structure, and X is a divalent group or a single bond.

[0015] (6) The present invention also provides the method according to item (5), wherein the polymer compound has a repeating unit represented by the following general formula (2a-2) or general formula (2b-2): [ka] (In the above general formula (2a-2), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent; X 2 is a divalent group, and X 3is an arylene group, and A is a single bond, -NH-, or an oxygen atom. In the general formula (2b-2), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and R 1 is an alkyl group having 1 to 10 carbon atoms which may have a substituent or an aryl group which may have a substituent, or R 1 and one R may be bonded to each other to form a cyclic structure, 2 is a divalent group, and X 3 is an arylene group, and A is a single bond, —NH—, or an oxygen atom.

[0016] (7) Furthermore, the present invention relates to X in the above general formula (2a-2) or general formula (2b-2). 3 is a phenylene group which may have a substituent, and A is a single bond.

[0017] (8) The present invention also provides a composition for decomposing a polymer compound having a partial structure represented by the following general formula (1), comprising an oxidizing agent, a basic compound, a catalyst, and a solvent, wherein the catalyst is at least one selected from the group consisting of an oxoacid of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten or a salt thereof, and a heteropolyacid or a salt thereof formed by condensation of such an oxoacid with an oxoacid of a heteroatom: [ka] (In the above general formula (1), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group which may have a substituent, or a single bond which bonds to an atom outside of general formula (1), and a single bond marked with a wavy line represents a bond to an atom outside of general formula (1).)

[0018] (9) The present invention also relates to the composition according to item (8), wherein the oxidizing agent is hydrogen peroxide or an organic peroxide.

[0019] (10) The present invention also relates to the composition according to item (9), wherein the solvent is an aqueous solvent. [Effects of the Invention]

[0020] According to the present invention, there is provided a method for decomposing a polymer compound having a partial structure represented by the above general formula (1), which can use an oxidizing agent with a relatively weak oxidizing action, and which can allow the oxidation of the sulfide moiety and the subsequent decomposition with a base to proceed in the same solution. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, one embodiment of the method for decomposing a polymer compound of the present invention and one embodiment of the composition for decomposing a polymer compound having a partial structure represented by the following general formula (1) will be described. Note that the present invention is not limited to the following embodiments and can be practiced with appropriate modifications within the scope of the present invention.

[0022] <Method for decomposing polymer compounds> The method for decomposing a polymer compound of the present invention targets a polymer compound having a partial structure represented by the following general formula (1), and is characterized in that an oxidizing agent is allowed to act on the polymer compound in the coexistence of a catalyst under basic conditions, and the catalyst is further characterized in that the catalyst is at least one compound selected from the group consisting of an oxoacid of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten or a salt thereof, and a heteropolyacid or a salt thereof formed by condensation of the oxoacid with an oxoacid of a heteroatom:

[0023] [ka]

[0024] As already explained, polymers having the partial structure represented by general formula (1) can be oxidized with an oxidizing agent and then treated with a base, causing intramolecular cleavage and lowering the molecular weight. However, oxidation with this oxidizing agent has traditionally required the use of relatively strong oxidizing agents such as persulfates, and attempting to use a base in the presence of such a strong oxidizing agent has presented the problem of the base being oxidized by the oxidizing agent, making it difficult for the reaction to proceed. This has resulted in the need to perform the oxidation treatment with an oxidizing agent and the treatment with a base separately, which is cumbersome.

[0025] In the present invention, by using a catalyst for oxidation treatment with an oxidizing agent, it is possible to sufficiently perform oxidation treatment even with weak oxidizing agents, such as hydrogen peroxide or organic peroxides, which do not exhibit oxidizing activity under basic conditions. Furthermore, the use of such weak oxidizing agents also inhibits the oxidation of bases by the oxidizing agent, allowing oxidation treatment and base treatment to be performed simultaneously. Furthermore, since molecular fragments with carboxylate structures produced by polymer decomposition are soluble in aqueous solvents, when oxidation treatment and base treatment are performed in these solvents using hydrogen peroxide or organic peroxides as an oxidizing agent, the solid polymer surface is decomposed by the oxidation and base treatment, and then the surface decomposition products dissolve, exposing a new surface. This new surface is then subjected to further oxidation and base treatment, ultimately resulting in the polymer being decomposed and completely solubilized in a single solution. This is a significant advantage over the conventional method proposed in Patent Document 3, and such an advantage is achieved by the use of weak oxidizing agents, such as hydrogen peroxide or organic peroxides, thanks to the catalyst newly adopted in the present invention. In the present invention, the term "aqueous solvent" refers to water, an organic solvent miscible with water, or a mixed solvent of water and an organic solvent miscible with water. This will be described later. First, the polymer to which the present invention is applied will be described.

[0026] In the general formula (1), each of the multiple Rs is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group which may have a substituent, or a single bond bonded to an atom outside the general formula (1). Examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, 2-ethylhexyl, octyl, nonyl, and decyl. Examples of such aryl groups include phenyl and naphthyl. In the general formula (1), a single bond marked with a wavy line represents a bond to another atom outside the general formula (1). As described above, R can also be a single bond bonded to an atom outside the general formula (1). For example, when one of the Rs bonded to the β-carbon of the sulfide is such a single bond, the partial structure represented by the general formula (1) becomes the following general formula (1-1), and can have a structure such as (A') shown in the chemical reaction formula above. As already mentioned, the polymer compound of the present invention exhibits degradability as long as it has the partial structure represented by the above general formula (1), and therefore the structures of the portions other than the partial structure represented by the above general formula (1) are not important.

[0027] [ka] (In the above general formula (1-1), R is the same as in the above general formula (1), and the single bond with a wavy line represents a bond to another atom outside the above general formula (1-1).)

[0028] More preferred examples of polymer compounds of the present invention include those having repeating units represented by the following general formula (2a) or (2b): In the example represented by the following general formula (2a), the partial structure represented by the above general formula (1) is incorporated into the main chain of the polymer compound, and in the example represented by the following general formula (2b), a part of the partial structure represented by the above general formula (1) is incorporated into the main chain of the polymer compound, while a sulfide moiety is present in the side chain of the polymer compound. In either case, the polymer compound is highly decomposed by treatment with an oxidizing agent and a base.

[0029] [ka]

[0030] In the general formula (2a), each R is independently selected and represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and X represents a divalent group. Examples of such alkyl groups include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group. Examples of such aryl groups include a phenyl group and a naphthyl group.

[0031] In the general formula (2b), each R is independently determined and represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and R 1 is an alkyl group having 1 to 10 carbon atoms which may have a substituent or an aryl group which may have a substituent, or R 1 and one R may bond to each other to form a cyclic structure, and X is a divalent group or a single bond. Examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, 2-ethylhexyl, octyl, nonyl, and decyl groups. Examples of such aryl groups include phenyl and naphthyl groups.

[0032] In addition, general formula (2b) includes a partial structure of the general formula (1-1) in which one of the Rs bonded to the β-carbon of the sulfide in the general formula (1) is a single bond bonded to an atom outside the general formula (1), and therefore includes a partial structure of the general formula (1). That is, general formula (2b) includes a partial structure of the general formula (1) in which X- is bonded to the middle single bond of the three single bonds marked with wavy lines and R is bonded to the single bond on the right side in the structure of general formula (1-1) in which one of the Rs bonded to the β-carbon of the sulfide in the general formula (1) is a single bond bonded to an atom outside the general formula (1). 1corresponds to the combination of

[0033] In general formula (2b), "R 1 and one R bonded to each other to form a cyclic structure" means that R 1 and any R bond together to form a ring structure, 1 This means that a heterocyclic ring containing a sulfur atom adjacent to R is formed. When forming such a ring structure, R 1 Preferably, R bonds to R bonded to the α-carbon of the sulfide to form a cyclic structure. Examples of such a cyclic structure include five-membered rings such as 1,3-dithiolane, 1,2-dithiolane, and tetrahydrothiophene, and six-membered rings such as thiane, dithiane, thiomorpholine, thiopyran, and dithiin. As an example for understanding, in general formula (2b), R 1 When these bond with the R bonded to the α-carbon of the sulfide to form a 1,3-dithiolane structure, the repeating unit shown on the left below is obtained. Note that this structure also has the partial structure shown in general formula (1) above. In other words, if we explain this using the general formula shown on the right below, the area surrounded by the multiple wavy lines attached to the single bond is general formula (1) above. In this way, in general formula (1) above, R can also be a single bond bonded to an atom outside general formula (1), so the repeating unit shown on the left below also has the partial structure represented by general formula (1).

[0034] [ka]

[0035] An example of the polymer compound represented by the general formula (2a) above is a polysulfide having a repeating unit represented by the following general formula (2a-A): In the polysulfide represented by the following general formula (2a-A), X in the general formula (2a) also contains the partial structure represented by the general formula (1).

[0036] [ka]

[0037] In the general formula (2a-A), each R is independently a divalent group. Examples of such a group include an alkylene group having 1 to 10 carbon atoms, an arylene group, and a group in which multiple alkylene groups and / or arylene groups are linked to each other via a hetero atom, a carbonyl group, or a single bond.

[0038] Furthermore, examples of polymer compounds in which X represented by the above general formula (2a) or general formula (2b) is more specifically represented include those having a repeating unit represented by the following general formula (2a-1) or general formula (2b-1):

[0039] [ka]

[0040] In the general formula (2a-1), each R is independently determined, and the details thereof are the same as those in the general formula (2a). 1 is a divalent group, and A is a single bond, -NH-, or an oxygen atom. When A is a single bond, the polymer compound represented by general formula (2a-1) is a polyester, when A is -NH-, the polymer compound represented by general formula (2a-1) is a polyurethane, and when A is an oxygen atom, the polymer compound represented by general formula (2a-1) is a polycarbonate.

[0041] In the general formula (2b-1), each R is independently determined and is the same as that in the general formula (2b), 1 is the same as in the general formula (2b), and R 1 In the same manner as in the general formula (2b), one R may be bonded to another to form a cyclic structure. 1is a divalent group, and A is a single bond, -NH-, or an oxygen atom. When A is a single bond, the polymer compound represented by general formula (2b-1) is a polyester, when A is -NH-, the polymer compound represented by general formula (2a-1) is a polyurethane, and when A is an oxygen atom, the polymer compound represented by general formula (2a-1) is a polycarbonate.

[0042] In addition, general formula (2b-1) includes a partial structure of the general formula (1-1) in which one of Rs bonded to the β carbon of the sulfide in the general formula (1) becomes a single bond bonded to an atom outside the general formula (1), and therefore includes a partial structure of the general formula (1). That is, general formula (2b-1) is a partial structure of the general formula (1-1) in which one of Rs bonded to the β carbon of the sulfide in the general formula (1) becomes a single bond bonded to an atom outside the general formula (1), and the middle single bond of the three single bonds marked with wavy lines has X in it. 1 -A- is bonded, and R is bonded to the single bond on the right 1 corresponds to the combination of

[0043] In addition, X represented by the above general formula (2a-1) or general formula (2b-1) 1 More specifically, polymer compounds having repeating units represented by the following general formula (2a-2) or (2b-2) can be given.

[0044] [ka]

[0045] In the general formula (2a-2), each R is independently determined and has the same meaning as in the general formula (2a). In the general formula (2a-2), A is a single bond, -NH-, or an oxygen atom, and X 2 is a divalent group, and X 3is an arylene group. Preferred examples of such an arylene group include a phenylene group which may have a substituent, a naphthylene group which may have a substituent, and a group in which a plurality of arylene groups are linked to each other via an alkylene group, a hetero atom, a carbonyl group, or a single bond.

[0046] In the general formula (2b-2), each R is independently determined and is the same as that in the general formula (2b), 1 is the same as in the general formula (2b), and R 1 In the same manner as in the general formula (2b), X and one R may be bonded to each other to form a cyclic structure. In the general formula (2b-2), A is a single bond, —NH—, or an oxygen atom; 2 is a divalent group, and X 3 is an arylene group. Preferred examples of such an arylene group include a phenylene group which may have a substituent, a naphthylene group which may have a substituent, and a group in which a plurality of arylene groups are linked to each other via an alkylene group, a hetero atom, a carbonyl group, or a single bond.

[0047] In addition, general formula (2b-2) includes a partial structure of the general formula (1-1) in which one of the Rs bonded to the β-carbon of the sulfide in the general formula (1) is a single bond bonded to an atom outside the general formula (1), and therefore includes a partial structure of the general formula (1). That is, general formula (2b-2) includes a partial structure of the general formula (1-1) in which one of the Rs bonded to the β-carbon of the sulfide in the general formula (1) is a single bond bonded to an atom outside the general formula (1), and the middle single bond of the three single bonds marked with wavy lines has X in it. 2 -X 3 -A- is bonded, and R is bonded to the single bond on the right 1 corresponds to the combination of

[0048] An example of the polymer compound represented by the general formula (2a-2) is a polyester having a repeating unit represented by the following chemical formula: In this polyester, X in the general formula (2a-2) 3becomes a phenylene group, A becomes a single bond, each R becomes a hydrogen atom, and X 2 becomes a divalent group represented by -CH2CH2O(C=O)-.

[0049] [ka]

[0050] Another example of the polymer compound represented by the general formula (2a-2) is a polyurethane having a repeating unit represented by the following chemical formula: In this polyurethane, X surrounded by a dashed square in the following chemical formula: 2 , X 3 and each portion of A is X in the above general formula (2a-2). 2 , X 3 and A, and each R in the above general formula (2a-2) is a hydrogen atom.

[0051] [ka]

[0052] An example of the polymer compound represented by the general formula (2b-1) is a polyester having a repeating unit represented by the following chemical formula: In this polyester, X in the general formula (2b-1) 1 corresponds to the area enclosed by the dashed rectangle in the chemical formula below, A is a single bond, and R 1 and one R bond together to form a cyclic thioacetal (1,3-dithiolane structure), and the remaining R is a hydrogen atom.

[0053] [ka]

[0054] An example of the polymer compound represented by the general formula (2b-2) is a polyester having a repeating unit represented by the following chemical formula: In this polyester, each R in the general formula (2b-2) is a hydrogen atom, and R1 becomes a butyl group, and X 2 is the part enclosed by the dashed rectangle in the chemical formula below, and X 3 becomes a p-phenylene group and A becomes a single bond.

[0055] [ka]

[0056] An example of the polymer compound represented by the general formula (2b-2) is a polyester having a repeating unit represented by the following chemical formula: In this polyester, each R in the general formula (2b-2) is a hydrogen atom, and R 1 becomes a butyl group, and X 2 is the part enclosed by the dashed rectangle in the chemical formula below, and X 3 becomes an o-phenylene group and A becomes a single bond.

[0057] [ka]

[0058] It goes without saying that the polymer compounds to which the present invention is applicable are not limited to polymer compounds having these exemplified repeating units.

[0059] The decomposition method of the present invention is characterized in that an oxidizing agent is allowed to act on the polymer compound described above in the presence of a catalyst under basic conditions. Specifically, the polymer compound is decomposed by contacting the polymer compound described above with a solution containing a basic compound, an oxidizing agent, and a catalyst. These matters will now be described.

[0060] Examples of basic compounds include sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, triethylamine, sodium phosphate, disodium monohydrogen phosphate, 1,8-diazabicyclo[5.4.0]undec-7-ene, and tetramethylguanidine. Among these, sodium carbonate is preferred. The amount of the basic compound in the solution can be about 1 to 10 equivalents relative to the number of partial structures represented by the general formula (1) contained in the polymer compound, but more amounts may also be used.

[0061] Examples of oxidizing agents include, but are not limited to, common oxidizing agents, such as hydrogen peroxide, metachloroperbenzoic acid and its salts, perbenzoic acid and its salts, peracetic acid and its salts, persulfuric acid and its salts, perboric acid and its salts, chlorine, bromine, iodine, hypochlorous acid and its salts, hypobromous acid and its salts, hypoiodous acid and its salts, chlorous acid and its salts, bromous acid and its salts, iodous acid and its salts, chloric acid and its salts, bromic acid and its salts, iodic acid and its salts, perchloric acid and its salts, perbromic acid and its salts, periodic acid and its salts, hypervalent iodine compounds, ozone, nitrogen dioxide, and nitric oxide. It is known that the oxidizing activity of hydrogen peroxide and organic peroxides decreases under basic conditions. However, in the present invention, hydrogen peroxide and organic peroxides can also be preferably used as oxidizing agents by using a catalyst described below in combination. The amount of oxidizing agent in the solution can be about 1 to 10 equivalents relative to the number of partial structures represented by the above general formula (1) contained in the polymer compound, but a greater amount may also be used.

[0062] The catalyst used is at least one selected from the group consisting of oxoacids of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten or salts thereof, and heteropolyacids or salts thereof obtained by condensing such oxoacids with oxoacids of heteroatoms.

[0063] Oxoacids of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten are acids containing an anion formed by combining vanadium(V), niobium(V), tantalum(V), chromium(VI), molybdenum(VI), or tungsten(VI) with oxygen, such as vanadic acid, niobic acid, tantalic acid, chromic acid, molybdic acid, and tungstic acid. Examples of these salts include lithium salts, sodium salts, potassium salts, cesium salts, and ammonium salts.

[0064] Heteropolyacids obtained by condensing an oxoacid of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten with an oxoacid of a heteroatom can also be used as the catalyst of the present invention. Examples of heteroatoms in this case include Si, P, As, S, I, Fe, Co, Ni, Cu, Al, and Ga. Preferred examples of such heteropolyacids include phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, phosphovanadic acid, silicovanadic acid, tungstomolybdophosphoric acid, tungstomolybdosilicic acid, and phosphovanadomolybdic acid. Examples of their salts include lithium salts, sodium salts, potassium salts, cesium salts, and ammonium salts.

[0065] The amount of catalyst in the solution may be about 0.001 to 0.5 equivalents relative to the number of partial structures represented by the general formula (1) contained in the polymer compound, but a greater amount may also be used.

[0066] The solvent constituting the solution is not particularly limited as long as it dissolves the above-mentioned base compound, oxidizing agent, and catalyst. Such a solvent is preferably an aqueous solvent. As described above, in the present invention, "aqueous solvent" refers to water, a water-miscible organic solvent, or a mixed solvent of water and a water-miscible organic solvent. Hydrogen peroxide is commercially available as an aqueous solution of hydrogen peroxide. When hydrogen peroxide is used as the oxidizing agent, the water contained therein is supplied to the reaction system. Thus, the water contained in hydrogen peroxide is naturally included in the "aqueous solvent" of the present invention. Preferred examples of water-miscible organic solvents used as aqueous solvents in the present invention include alcohol, tetrahydrofuran, dimethylacetamide, 1,4-dioxane, methyl cellosolve, butyl cellosolve, N-methylpiperidinone, 1,2-dimethoxyethane, diglyme, acetonitrile, etc. Preferred examples of alcohol include methanol, ethanol, propanol, isopropanol, etc.

[0067] The polymer compound is decomposed by contacting the polymer compound with a solution containing the above-mentioned components. Examples of the polymer compound in this case include plastic products and adhesives made of polymer compounds. The means for contacting these is not particularly limited, but preferred examples include immersing the polymer compound in the solution and spraying the solution onto the polymer compound.

[0068] <Composition for decomposing polymer compounds> The present invention also provides a composition for decomposing a polymer compound having the partial structure represented by the general formula (1). This composition comprises an oxidizing agent, a basic compound, a catalyst, and a solvent, and is characterized in that the catalyst is at least one selected from the group consisting of an oxoacid of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten, or a salt thereof, and a heteropolyacid or a salt thereof formed by condensation of such an oxoacid with an oxoacid of a heteroatom. These matters have already been explained, so further explanation will be omitted here. [Example]

[0069] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the following examples in any way.

[0070] [Synthesis of Polyester A] [ka]

[0071] Under an argon atmosphere, 1.7 mL of triethylamine was added to a methylene chloride solution (3 mL) of terephthaloyl chloride (0.609 g, 3.00 mmol) and 2,2'-thiodiethanol (0.367 g, 3.00 mmol), and the mixture was stirred overnight. The reaction mixture was poured into 200 mL of methanol with vigorous stirring, and the precipitate was collected by filtration, washed thoroughly with methanol, and then vacuum dried to obtain polyester A (yield 0.696 g) as a white powder.

[0072] [Synthesis of Polyester B] [ka]

[0073] Under an argon atmosphere, 1.7 mL of triethylamine was added to a methylene chloride solution (3 mL) of isophthalic acid chloride (0.609 g, 3.00 mmol) and 2,2'-thiodiethanol (0.367 g, 3.00 mmol), and the mixture was stirred overnight. The reaction mixture was poured into 200 mL of methanol with vigorous stirring, and the precipitate was collected by filtration, washed thoroughly with methanol, and then vacuum dried to obtain polyester B (yield 0.681 g) as a white powder.

[0074] [Decomposition experiment of polyester A] 100 mg of polyester A powder was dispersed in methanol (15 mL), to which 100 mg of sodium tungstate dihydrate, 5 mL of 30% hydrogen peroxide, and 400 mg of sodium carbonate were added and stirred for 4 hours. Since 70% of the water contained in the 30% hydrogen peroxide was also supplied to the reaction system, the reaction took place in a mixed solvent of water and methanol. When water was then added to this solution, a homogeneous aqueous solution was obtained, indicating that polyester A had been decomposed.

[0075] [Decomposition experiment of polyester B] 20 mg of polyester B powder was dispersed in methanol (1 mL), and 15 mg of sodium phosphomolybdate hydrate, 1 mL of 30% hydrogen peroxide, and 84 mg of sodium carbonate were added and stirred for 2 hours. Since 70% of the water contained in the 30% hydrogen peroxide was also supplied to the reaction system, the reaction took place in a mixed solvent of water and methanol. When water was then added to this solution, a homogeneous aqueous solution was obtained, indicating that polyester B had been decomposed.

Claims

1. A method for decomposing a polymer compound having a partial structure represented by the following general formula (1), characterized in that an oxidizing agent is allowed to act on the polymer compound in the coexistence of a catalyst under basic conditions: The method according to the present invention, wherein the catalyst is at least one selected from the group consisting of an oxoacid of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten, or a salt thereof, and a heteropolyacid or a salt thereof obtained by condensing such an oxoacid with an oxoacid of a heteroatom. 【Chemical 1】 (In the above general formula (1), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group which may have a substituent, or a single bond which bonds to an atom outside of general formula (1), and a single bond marked with a wavy line represents a bond to an atom outside of general formula (1).)

2. 2. The method according to claim 1, wherein the amount of the catalyst is 0.001 to 0.5 equivalents relative to the number of partial structures represented by general formula (1) contained in the polymer compound.

3. 2. The method of claim 1, wherein the oxidizing agent is hydrogen peroxide or an organic peroxide.

4. 4. The method according to claim 3, wherein the decomposition is carried out in an aqueous solvent.

5. The method according to any one of claims 1 to 4, wherein the polymer compound has a repeating unit represented by the following general formula (2a) or (2b): 【Chemistry 2】 (In the above general formula (2a), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and X is a divalent group. In the above general formula (2b), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and R １ is an alkyl group having 1 to 10 carbon atoms which may have a substituent or an aryl group which may have a substituent, or R １ and one R may be bonded to each other to form a cyclic structure, and X is a divalent group or a single bond.

6. The method according to claim 5, wherein the polymer compound has a repeating unit represented by the following general formula (2a-2) or general formula (2b-2): 【Chemistry 3】 (In the above general formula (2a-2), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent; X ２ is a divalent group, and X ３ is an arylene group, and A is a single bond, —NH—, or an oxygen atom. In the general formula (2b-2), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group which may have a substituent, and R １ is an alkyl group having 1 to 10 carbon atoms which may have a substituent or an aryl group which may have a substituent, or R １ and one R may be bonded to each other to form a cyclic structure, ２ is a divalent group, and X ３ is an arylene group, and A is a single bond, —NH—, or an oxygen atom.

7. X in the general formula (2a-2) or (2b-2) ３ 7. The method according to claim 6, wherein is an optionally substituted phenylene group, and A is a single bond.

8. An oxidizing agent, a basic compound, a catalyst, and a solvent, The composition for decomposing a polymer compound having a partial structure represented by the following general formula (1), characterized in that the catalyst is at least one selected from the group consisting of an oxoacid of vanadium, niobium, tantalum, chromium, molybdenum, or tungsten or a salt thereof, and a heteropolyacid or a salt thereof obtained by condensing such an oxoacid with an oxoacid of a heteroatom: 【Chemistry 4】 (In the above general formula (1), each R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group which may have a substituent, or a single bond which bonds to an atom outside of general formula (1), and a single bond marked with a wavy line represents a bond to an atom outside of general formula (1).)

9. 9. The composition of claim 8, wherein the oxidizing agent is hydrogen peroxide or an organic peroxide.

10. The composition according to claim 9, wherein the solvent is an aqueous solvent.

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