Method for producing decomposition product of ester bond-containing polymer and method for producing ester bond-containing polymer

Abstract

To provide a method for producing a decomposition product of an ester bond-containing polymer capable of obtaining a highly reactive decomposition product, and capable of suppressing generation of glycol that is a by-product.SOLUTION: A method for producing decomposition products of an ester bond-containing polymer according to the present invention includes a mixing step of obtaining a mixture containing a substance that includes the ester bond-containing polymer, a compound (X), and a compound (Y), as well as a decomposition step of breaking down the polymer containing ester bonds. The compound (X) is a compound that has a hydroxyl group and an unsaturated bond (X) that is different from the double bond included in the aromatic ring, while the compound (Y) is a compound that has two or more unsaturated bonds (Y) that are different from the double bond included in the aromatic ring. The compounds (X) and (Y) are different compounds.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a decomposition product of an ester bond-containing polymer. The present invention also relates to a method for producing an ester bond-containing polymer using the decomposition product obtained by the above production method. [Background technology]

[0002] Products containing ester bond-containing polymers are widely used. Among ester bond-containing polymers, unsaturated polyester resin cured products have high durability and are used in products in various fields. For example, unsaturated polyester resin cured products are used as matrix resins for fiber-reinforced plastics.

[0003] In recent years, with the aim of realizing a recycling-oriented society, recycling of products using ester bond-containing polymers has been studied from the perspectives of thermal recycling, material recycling, chemical recycling, etc. Among these, chemical recycling is a method of decomposing an ester bond-containing polymer into raw material monomers, and therefore is a method that is highly suitable for closed-loop recycling because the quality of the reproduced ester bond-containing polymer is unlikely to deteriorate.

[0004] However, it is difficult to say that chemical recycling technology has been established for ester bond-containing polymers. In particular, recycling technology for cured unsaturated polyester resins has not yet been put into practical use, and most of them are disposed of by landfill treatment.

[0005] The following Patent Documents 1 and 2 disclose methods for decomposing cured unsaturated polyester resins.

[0006] Patent Document 1 discloses a method for treating a cured unsaturated polyester resin, in which the cured unsaturated polyester resin is decomposed or dissolved using a treatment liquid containing a phosphate salt from which water has been removed and an organic solvent.

[0007] Patent Document 2 discloses a method for depolymerizing an unsaturated polyester resin, which includes a step of using an alcohol having an unsaturated bond as a reaction solvent and depolymerizing the unsaturated polyester resin by irradiating the unsaturated polyester resin with microwaves in the presence of the reaction solvent under pressure conditions that are higher than atmospheric pressure but do not bring the reaction solvent into a supercritical or subcritical state. Patent Document 2 discloses allyl alcohol and ethylene glycol monoallyl ether as the alcohol having an unsaturated bond. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-255897 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-110155 Summary of the Invention [Problem to be solved by the invention]

[0009] In the method described in Patent Document 1, the decomposition products of the obtained cured unsaturated polyester resin have no reactivity, and therefore it is difficult to reproduce the cured unsaturated polyester resin using the decomposition products.

[0010] In the method described in Patent Document 2, a compound having an allyl group is obtained as a decomposition product of a cured unsaturated polyester resin. However, the decomposition product does not have high reactivity, making it difficult to reproduce a cured unsaturated polyester resin using the decomposition product. In addition, since a large amount of glycol is produced as a by-product, a step of removing the glycol is required to reproduce a cured unsaturated polyester resin. Furthermore, the method described in Patent Document 2 requires an apparatus capable of irradiating microwaves, which requires a large-sized apparatus on an industrial scale. Therefore, the method is not necessarily highly practical.

[0011] An object of the present invention is to provide a method for producing a decomposition product of an ester bond-containing polymer, which can obtain a highly reactive decomposition product and suppress the production of glycol as a by-product. Another object of the present invention is to provide a method for producing an ester bond-containing polymer using the decomposition product obtained by the above-mentioned production method. [Means for solving the problem]

[0012] This specification discloses the following methods for producing a degradation product of an ester bond-containing polymer and a method for producing an ester bond-containing polymer.

[0013] Item 1. A method for producing a decomposition product of an ester bond-containing polymer, comprising: a mixing step of obtaining a mixture containing a substance containing an ester bond-containing polymer, a compound (X), and a compound (Y); and a decomposition step of decomposing the ester bond-containing polymer, wherein the compound (X) is a compound having a hydroxyl group and an unsaturated bond (X) different from a double bond contained in an aromatic ring; the compound (Y) is a compound having two or more unsaturated bonds (Y) different from a double bond contained in an aromatic ring; and the compound (X) and the compound (Y) are different compounds.

[0014] Item 2. The method for producing a decomposition product of an ester bond-containing polymer according to Item 1, wherein the unsaturated bond (X) is an unsaturated bond contained in a (meth)acryloyl group, and the unsaturated bond (Y) is an unsaturated bond contained in a (meth)acryloyl group.

[0015] Item 3. The method for producing a decomposition product of an ester bond-containing polymer according to Item 1 or 2, wherein the compound (Y) does not have a hydroxyl group.

[0016] Item 4. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 3, wherein the mixing step is a step of mixing a solution containing the compound (X) and the compound (Y) with the substance.

[0017] Item 5. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 4, wherein the mixture contains a polymerization inhibitor.

[0018] Item 6. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 5, wherein in the decomposition step, the ester bond-containing polymer is decomposed by reacting the ester bond-containing polymer with the compound (X).

[0019] Item 7. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 6, wherein the decomposition step is carried out at a pressure of 0.2 MPa or more.

[0020] Item 8. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 7, wherein the mixture contains a metal catalyst, and the metal catalyst is a metal salt, a metal hydroxide, or a metal oxide.

[0021] Item 9. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 6, wherein the mixture contains a metal catalyst, and the metal catalyst is a metal salt, a metal hydroxide, or a metal oxide, and the decomposition step is carried out at a pressure of 0.2 MPa or less.

[0022] Item 10. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 9, wherein the compound (X) is hydroxyethyl methacrylate.

[0023] Item 11. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 10, wherein the compound (Y) is ethylene glycol dimethacrylate.

[0024] Item 12. The method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 11, wherein the ester bond-containing polymer is a cured product of an unsaturated polyester resin.

[0025] Item 13. A method for producing an ester bond-containing polymer, comprising a reaction step of reacting a decomposition product of an ester bond-containing polymer with an alkyd, wherein the decomposition product of the ester bond-containing polymer includes the decomposition product of an ester bond-containing polymer obtained by the method for producing a decomposition product of an ester bond-containing polymer according to any one of Items 1 to 12.

[0026] Item 14. A method for producing an ester bond-containing polymer according to Item 13, which is a method for producing a cured unsaturated polyester resin. [Effects of the Invention]

[0027] The method for producing a decomposition product of an ester bond-containing polymer according to the present invention comprises a mixing step of obtaining a mixture containing a substance containing an ester bond-containing polymer, compound (X), and compound (Y). The method for producing a decomposition product of an ester bond-containing polymer according to the present invention comprises a decomposition step of decomposing the ester bond-containing polymer. The compound (X) is a compound having a hydroxyl group and an unsaturated bond (X) different from the double bond contained in the aromatic ring. The compound (Y) is a compound having two or more unsaturated bonds (Y) different from the double bond contained in the aromatic ring. The compound (X) and the compound (Y) are different compounds. The method for producing a decomposition product of an ester bond-containing polymer according to the present invention has the above-mentioned configuration, so that a highly reactive decomposition product can be obtained and the production of glycol as a by-product can be suppressed. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram showing chemical reactions that proceed in a decomposition step in a method for producing a decomposition product of an ester bond-containing polymer (cured unsaturated polyester resin) according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing an example of a chemical reaction that proceeds in a reaction step in the process of producing an ester bond-containing polymer (cured unsaturated polyester resin). [Figure 3]FIG. 3(a) shows the chemical structural formula of glycol (G1) obtained in the Examples and Comparative Examples, FIG. 3(c) shows the chemical structural formula of glycol (G2) obtained in the Examples and Comparative Examples, and FIGS. 3(b) and 3(d) show the spectra obtained by H-NMR measurement of the Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be described in detail below.

[0030] (Method for producing decomposition products of ester bond-containing polymers) The method for producing a decomposition product of an ester bond-containing polymer according to the present invention includes a mixing step of obtaining a mixture containing a substance containing an ester bond-containing polymer, compound (X), and compound (Y).

[0031] The method for producing a decomposition product of an ester bond-containing polymer according to the present invention includes a decomposition step of decomposing the ester bond-containing polymer.

[0032] The compound (X) is a compound having a hydroxyl group and an unsaturated bond (X) different from the double bond contained in the aromatic ring. The compound (Y) is a compound having two or more unsaturated bonds (Y) different from the double bond contained in the aromatic ring. The compound (X) and the compound (Y) are different compounds.

[0033] The method for producing a decomposition product of an ester bond-containing polymer according to the present invention has the above-described configuration, and therefore, a highly reactive decomposition product can be obtained and the production of glycol as a by-product can be suppressed.

[0034] The method for producing a decomposition product of an ester bond-containing polymer according to the present invention has the above-mentioned configuration, and therefore, the decomposition product of an ester bond-containing polymer can be easily obtained, and the obtained decomposition product can be used to reproduce the ester bond-containing polymer.

[0035] In the method for producing a decomposition product of an ester bond-containing polymer according to the present invention, a specific compound (X) is used, and therefore the resulting decomposition product contains a highly reactive decomposition product. Therefore, the highly reactive decomposition product can act as a crosslinking agent, for example, when reproducing the ester bond-containing polymer. Furthermore, in the method for producing a decomposition product of an ester bond-containing polymer according to the present invention, a specific compound (Y) is used, and therefore the production of glycol as a by-product can be suppressed. Furthermore, since the compounds (X) and (Y) themselves contribute to the ester bond-containing polymer production reaction (crosslinking reaction), the decomposition product, the compounds (X) and (Y) can be reused as crosslinking agents without removing the compounds (X) and (Y) after the decomposition step. Therefore, the ester bond-containing polymer can be reproduced without removing the compounds (X) and (Y) after the decomposition step.

[0036] In the method for producing a decomposition product of an ester bond-containing polymer, the mixing step may obtain a mixture containing the substance, the compound (X), and the compound (Y). In the method for producing a decomposition product of an ester bond-containing polymer, the mixing step may obtain a mixture containing the substance, the compound (X), the compound (Y), and a metal-based catalyst, or may obtain a mixture containing the substance, the compound (X), the compound (Y), and a polymerization inhibitor. In the method for producing a decomposition product of an ester bond-containing polymer, the mixing step may obtain a mixture containing the substance, the compound (X), the compound (Y), a metal-based catalyst, and a polymerization inhibitor. The mixture may contain other components besides these.

[0037] First, the components that can be used in the present invention will be described.

[0038] <Substances containing ester bond-containing polymers> The substance includes an ester bond-containing polymer. The ester bond-containing polymer is a polymer having an ester bond. Only one type of the substance may be used, or two or more types may be used in combination. Only one type of the ester bond-containing polymer may be used, or two or more types may be used in combination.

[0039] Examples of the ester bond-containing polymer include polyester resins.

[0040] The ester bond-containing polymer is preferably a polyester resin, and more preferably a cured unsaturated polyester resin. Therefore, the method for producing the decomposition product of the ester bond-containing polymer is preferably a method for producing a decomposition product of a polyester resin, and more preferably a method for producing a decomposition product of a cured unsaturated polyester resin. The cured unsaturated polyester resin is a cured unsaturated polyester resin. Since recycling technology for cured unsaturated polyester resins has not yet been put into practical use, most of them are disposed of by landfill treatment. Therefore, when the ester bond-containing polymer is a cured unsaturated polyester resin, it can greatly contribute to reducing the environmental load.

[0041] The cured unsaturated polyester resin can be obtained, for example, by reacting an alkyd with a crosslinkable monomer (crosslinking agent). The alkyd can be obtained, for example, by reacting a saturated polybasic acid, an unsaturated polybasic acid, and a polyhydric alcohol.

[0042] Examples of the saturated polybasic acid include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, adipic acid, sebacic acid, HET acid (chlorendic acid), and tetrabromophthalic anhydride. The saturated polybasic acids may be used alone or in combination of two or more.

[0043] Examples of the unsaturated polybasic acid include fumaric acid, maleic acid, maleic anhydride, itaconic acid, etc. The unsaturated polybasic acids may be used alone or in combination of two or more.

[0044] Examples of the polyhydric alcohol include glycols and bisphenols. Examples of the glycol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, tripropylene glycol, polypropylene glycol, neopentyl glycol, 1,3-butanediol, 1,6-hexanediol, and dibromineopentyl glycol. Examples of the bisphenol include hydrogenated bisphenol A and bisphenol A propylene oxide adduct. The polyhydric alcohols may be used alone or in combination of two or more.

[0045] Examples of the crosslinkable monomer include vinyl monomers, allyl monomers, and (meth)acrylic acid esters. Examples of the vinyl monomer include styrene, vinyl toluene, α-methylstyrene, and vinyl acetate. Examples of the allyl monomer include diallyl phthalate, diallyl isophthalate, triallyl isocyanurate, and diallyl tetrabromophthalate. Examples of the (meth)acrylic acid ester include methyl (meth)acrylate, phenoxyethyl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and 2-hydroxyethyl (meth)acrylate. The (meth)acrylic is acrylic or methacrylic. The (meth)acrylate is acrylate or methacrylate. The crosslinkable monomer may be used alone or in combination of two or more.

[0046] The weight average molecular weight of the ester bond-containing polymer may be 1,000 or more, 10,000 or more, or 100,000 or more, or 100,000 or less, 10,000 or less, or 1,000 or less.

[0047] The weight average molecular weight of the ester bond-containing polymer is a weight average molecular weight measured by gel permeation chromatography (GPC) and converted into polystyrene.

[0048] From the viewpoint of recycling, the substance preferably includes waste containing the ester bond-containing polymer, such as waste generated after using a molded article (product) containing the ester bond-containing polymer and defective products generated during the production of a molded article (product) containing the ester bond-containing polymer.

[0049] The substance may contain only the ester bond-containing polymer, or may contain the ester bond-containing polymer and a component other than the ester bond-containing polymer.

[0050] Examples of components other than the ester bond-containing polymer include glass fiber, carbon fiber, organic fiber, satin fabric, aramid fiber, boron fiber, silica sand, colorants, calcium carbonate, calcium carbide, talc, aluminum hydroxide, thickeners, internal mold release agents, reactive diluents, low-profile agents, antioxidants, modifiers, flame retardants, and antibacterial agents. The glass fiber may be contained in the form of a glass mat, glass cloth, or chopped strands used in sheet molding compounds (SMC). Only one of the above components may be used, or two or more may be used in combination. The material may, for example, contain the ester bond-containing polymer and glass fiber, the ester bond-containing polymer and silica sand, or the ester bond-containing polymer, glass fiber, and silica sand.

[0051] The content of the ester bond-containing polymer in 100% by weight of the substance may be 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. The content of the ester bond-containing polymer in 100% by weight of the substance may be 100% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 30% by weight or less, or 20% by weight or less.

[0052] <Compound (X)> The compound (X) has a hydroxyl group. The compound (X) has an unsaturated bond (X) that is different from the double bond contained in the aromatic ring. The unsaturated bond (X) is different from the double bond contained in the aromatic ring. The compound (X) has a hydroxyl group and an unsaturated bond (X). Only one type of the compound (X) may be used, or two or more types may be used in combination.

[0053] The compound (X) may have only one hydroxyl group, may have two, may have two or more, may have three, may have three or more, may have five or less, may have four or less, or may have three or less hydroxyl groups.

[0054] The compound (X) may or may not have an aromatic ring. The compound (X) may or may not have a double bond contained in the aromatic ring.

[0055] The compound (X) may have only one unsaturated bond (X), may have two, may have two or more, may have three, may have three or more, may have five or less, may have four or less, or may have three or less unsaturated bonds (X).

[0056] The unsaturated bond (X) is preferably a double bond. The compound (X) preferably has a double bond.

[0057] Examples of the unsaturated bond (X) include an unsaturated bond (double bond) contained in an allyl group and an unsaturated bond (double bond) contained in a (meth)acryloyl group.

[0058] The compound (X) is preferably a compound having crosslinking reactivity. In this case, the decomposition product and the compound (X) can be reused as a crosslinking agent. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (X) after the decomposition step.

[0059] The compound (X) is preferably a liquid at 20° C. That is, the melting point of the compound (X) is preferably less than 20° C., and the boiling point is preferably greater than 20° C. In this case, the substance can be well mixed with the compound (X) and the compound (Y) in the mixing step.

[0060] The boiling point of the compound (X) is preferably 95°C or higher, more preferably 100°C or higher, and even more preferably 150°C or higher. In this case, heating under reflux can be carried out well in the decomposition step. The boiling point of the compound (X) may be 300°C or lower, or may be 250°C or lower.

[0061] The compound (X) preferably has an unsaturated bond (X) at a terminal. In this case, the decomposition product and the compound (X) can be reused as a crosslinking agent. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (X) after the decomposition step. When the compound (X) has an unsaturated bond (X) at a terminal, the compound (X) may also have an unsaturated bond (X) at a portion other than the terminal, or may have an unsaturated bond (X) only at the terminal.

[0062] The compound (X) preferably has a double bond at its terminal, and more preferably has a structure represented by the following formula (X-1). In this case, the decomposition product and the compound (X) can be reused as a crosslinking agent. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (X) after the decomposition step. The structure represented by the following formula (X-1) has a double bond at its terminal.

[0063] [ka]

[0064] In the above formula (X-1), R represents a hydrogen atom or a methyl group, and * represents the bonding position to other atoms. In the above formula (X-1), R may be a hydrogen atom or a methyl group.

[0065] The molecular weight of the compound (X) may be 75 or more, 100 or more, 1000 or less, 500 or less, 300 or less, 200 or less, or 150 or less.

[0066] The compound (X) preferably has a (meth)acryloyl group. The unsaturated bond (X) is preferably an unsaturated bond contained in a (meth)acryloyl group. In this case, a decomposition product with even higher reactivity can be obtained. Furthermore, the decomposition product and the compound (X) can be reused as crosslinking agents. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (X) after the decomposition step. The (meth)acryloyl group has a structure represented by the formula (X-1) above. The (meth)acryloyl group is an acryloyl group or a methacryloyl group. An acryloyl group is sometimes called an acrylic group, and a methacryloyl group is sometimes called a methacrylic group.

[0067] Examples of the compound (X) having an acryloyl group include ethylene glycol monoacrylate (2-hydroxyethyl acrylate), 4-hydroxybutyl acrylate, polyethylene glycol monoacrylate, and polypropylene glycol monoacrylate.

[0068] Examples of the compound (X) having a methacryloyl group include hydroxyethyl methacrylate (ethylene glycol methacrylate or 2-hydroxyethyl methacrylate), p-hydroxyphenyl methacrylate (4-hydroxyphenyl methacrylate), glycerin monomethacrylate, polyethylene glycol monomethacrylate, hydroxypropyl methacrylate, polypropylene glycol monomethacrylate, and hydroxyphenyl methacrylate.

[0069] The compound (X) is preferably hydroxyethyl (meth)acrylate, and more preferably hydroxyethyl methacrylate, in which case the effects of the present invention can be more effectively exhibited.

[0070] <Compound (Y)> The compound (Y) has two or more unsaturated bonds (Y) that are different from the double bonds contained in the aromatic ring. The unsaturated bonds (Y) are different from the double bonds contained in the aromatic ring. The compound (Y) has two or more unsaturated bonds (Y). The compound (Y) is a compound that is different from the compound (X). Only one type of the compound (Y) may be used, or two or more types may be used in combination.

[0071] The compound (Y) may or may not have a hydroxyl group. From the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the compound (Y) does not have a hydroxyl group. It is preferable that the compound (Y) is a compound that does not react with the ester bond-containing polymer.

[0072] The compound (Y) may or may not have an aromatic ring. The compound (Y) may or may not have a double bond contained in the aromatic ring.

[0073] The compound (Y) may have only two unsaturated bonds (Y), or may have two or more unsaturated bonds (Y), or may have three unsaturated bonds (Y), or may have five or less unsaturated bonds (Y), or may have four or less unsaturated bonds (Y), or may have three or less unsaturated bonds (Y).

[0074] The unsaturated bond (Y) is preferably a double bond. The compound (Y) preferably has two or more double bonds.

[0075] Examples of the unsaturated bond (Y) include an unsaturated bond (double bond) contained in an allyl group and an unsaturated bond (double bond) contained in a (meth)acryloyl group.

[0076] The compound (Y) is preferably a compound having crosslinking reactivity. In this case, the decomposition product and the compound (Y) can be reused as a crosslinking agent. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (Y) after the decomposition step.

[0077] The compound (Y) is preferably a liquid at 20° C. That is, the melting point of the compound (Y) is preferably less than 20° C., and the boiling point is preferably greater than 20° C. In this case, the substance can be well mixed with the compound (X) and the compound (Y) in the mixing step.

[0078] The boiling point of the compound (Y) is preferably 95°C or higher, more preferably 100°C or higher, and even more preferably 150°C or higher. In this case, heating under reflux can be carried out well in the decomposition step. The boiling point of the compound (Y) may be 300°C or lower, or may be 250°C or lower.

[0079] The compound (Y) preferably has an unsaturated bond (Y) at a terminal, and more preferably at both terminals. In this case, the decomposition product and the compound (Y) can be reused as a crosslinking agent. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (Y) after the decomposition step. When the compound (Y) has an unsaturated bond (Y) at a terminal, the compound (Y) may also have an unsaturated bond (Y) at a portion other than the terminal, or may have an unsaturated bond (Y) only at the terminal.

[0080] The compound (Y) preferably has a double bond at its terminal, more preferably at both terminals, and even more preferably at the structure represented by the following formula (Y-1), and particularly preferably at both terminals. In this case, the decomposition product and the compound (Y) can be reused as a crosslinking agent. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (Y) after the decomposition step. The structure represented by the following formula (Y-1) has a double bond at its terminal.

[0081] [ka]

[0082] In the above formula (Y-1), R represents a hydrogen atom or a methyl group, and * represents the bonding position to other atoms. In the above formula (Y-1), R may be a hydrogen atom or a methyl group.

[0083] The molecular weight of the compound (Y) may be 75 or more, 100 or more, 1000 or less, 500 or less, 300 or less, 200 or less, or 150 or less.

[0084] The compound (Y) preferably has a (meth)acryloyl group. The unsaturated bond (Y) is preferably an unsaturated bond contained in a (meth)acryloyl group. In this case, the generation of glycol as a by-product can be more effectively suppressed. In addition, the decomposition product and the compound (Y) can be reused as a crosslinking agent. Therefore, the ester bond-containing polymer can be reproduced without removing the compound (Y) after the decomposition step. The (meth)acryloyl group has a structure represented by the formula (Y-1). The (meth)acryloyl group is an acryloyl group or a methacryloyl group. An acryloyl group is sometimes called an acrylic group, and a methacryloyl group is sometimes called a methacrylic group.

[0085] Examples of the compound (Y) having an acryloyl group include ethylene glycol diacrylate (ethylene diacrylate), tetramethylene glycol diacrylate (1,4-bis(acryloyloxy)butane), polyethylene glycol diacrylate, and polypropylene glycol diacrylate.

[0086] Examples of the compound (Y) having a methacryloyl group include ethylene glycol dimethacrylate (ethylene dimethacrylate), glycerol dimethacrylate, polyethylene glycol dimethacrylate, and polypropylene glycol dimethacrylate.

[0087] The compound (Y) is preferably ethylene glycol di(meth)acrylate, and more preferably ethylene glycol dimethacrylate, in which case the effects of the present invention can be more effectively exhibited.

[0088] <Metal catalyst> In the mixing step, a metal catalyst may or may not be used. When a metal catalyst is used in the mixing step, the mixture contains the metal catalyst. The metal catalyst is a catalyst containing a metal atom. Only one type of the metal catalyst may be used, or two or more types may be used in combination.

[0089] The metal catalyst is not particularly limited as long as it can catalyze the chemical reaction between the ester bond-containing polymer and the compound (X).

[0090] Examples of the metal catalyst include metal salts, metal hydroxides, and metal oxides.

[0091] Examples of metals contained in the metal catalyst include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, titanium, zirconium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, palladium, zinc, aluminum, gallium, and tin.

[0092] Examples of the metal salt include metal phosphates, metal alkoxides, and metal amides. The metal phosphates may be orthophosphates, pyrophosphates, metaphosphates, or polyphosphates. Examples of the metal salt include metal salts containing the above-mentioned metals, and more specifically, examples thereof include tripotassium phosphate and sodium ethoxide.

[0093] Examples of the metal hydroxide include metal hydroxides containing the above-mentioned metals, and more specific examples include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, titanium hydroxide, zirconium hydroxide, vanadium hydroxide, chromium hydroxide, manganese hydroxide, iron hydroxide, cobalt hydroxide, nickel hydroxide, copper hydroxide, silver hydroxide, palladium hydroxide, zinc hydroxide, aluminum hydroxide, gallium hydroxide, and tin hydroxide.

[0094] The metal oxides include metal oxides containing the above-mentioned metals, and more specifically, copper oxide, titanium dioxide, iron oxide, manganese oxide, vanadium oxide, tin oxide, zinc oxide, and aluminum oxide.

[0095] From the viewpoint of further increasing the decomposition efficiency of the ester bond-containing polymer, the metal catalyst is preferably a metal salt, a metal hydroxide, or a metal oxide, more preferably a metal salt, and even more preferably tripotassium phosphate.

[0096] <Polymerization inhibitor> In the mixing step, a polymerization inhibitor may or may not be used. When a polymerization inhibitor is used in the mixing step, the mixture contains the polymerization inhibitor. By using the polymerization inhibitor, unintended polymerization reactions in the decomposition step can be suppressed. The polymerization inhibitor may be used alone or in combination of two or more types.

[0097] Examples of the polymerization inhibitor include hydroquinone, phenothiazine, catechol, benzoquinone, tertiary butyl catechol, p-methoxyphenol, tertiary butyl hydroquinone, p-benzoquinone, chloranil, m-dinitrobenzene, nitrobenzene, p-phenyldiamine, sulfur, diphenylpicrylhydrazyl, di-p-fluorophenylamine, tri-p-nitrophenylmethyl, 2,6-di-tert-butyl-4-methylphenol, 2,2,6,6-tetramethylpiperidine 1-oxyl, and copper naphthenate.

[0098] The polymerization inhibitor is preferably 2,2,6,6-tetramethylpiperidine 1-oxyl, in which case the effects of the present invention can be more effectively exhibited.

[0099] <Other ingredients> In the mixing step, other components (components other than the substance, compound (X), compound (Y), metal catalyst, and polymerization inhibitor) may or may not be used. Examples of the other components include a crosslinkable monomer and a dilution solvent. Only one type of the other components may be used, or two or more types may be used in combination.

[0100] Examples of the crosslinkable monomer include those listed in the above section on "Substances containing ester bond-containing polymers." The crosslinkable monomer may be used alone or in combination of two or more. The crosslinkable monomer is preferably styrene. That is, in the mixing step, a mixture containing the substance, the compound (X), the compound (Y), and styrene is preferably obtained. In this case, the solubility of the decomposition product obtained after the decomposition step can be increased, and the decomposition product can be reused as a crosslinking agent.

[0101] The method for producing the decomposition product of the ester bond-containing polymer will be described in more detail below.

[0102] <Mixing process> The mixing step is a step of obtaining a mixture containing the substance, the compound (X), and the compound (Y). As described above, the mixture may contain the metal catalyst and the polymerization inhibitor. The mixture may also contain the other component (e.g., styrene).

[0103] The mixing step is carried out, for example, by charging the substance, the compound (X), and the compound (Y) into a container. The mixing step is preferably a step of mixing the substance with a solution containing the compound (X) and the compound (Y), and more preferably a step of adding the substance to a solution containing the compound (X) and the compound (Y). The mixing step may also be a step of immersing the substance in a solution containing the compound (X) and the compound (Y). The solution may contain the metal catalyst, the polymerization inhibitor, or the other components.

[0104] In the mixture, the substance, the compound (X), and the compound (Y) may or may not be uniformly mixed. For example, in the mixture, the substance may sink to the bottom of the container.

[0105] The substance mixed in the mixing step is preferably a pulverized waste product containing the ester bond-containing polymer, which can increase the contact area between the substance and the compound (X), thereby allowing the decomposition reaction to proceed more efficiently.

[0106] In the mixture, the content of the substance relative to 100 parts by weight of the total of the compound (X) and the compound (Y) is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and preferably 100 parts by weight or less, more preferably 50 parts by weight or less. When the content of the substance is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0107] In the mixture, the content of the ester bond-containing polymer in the substance relative to 100 parts by weight of the total of the compound (X) and the compound (Y) is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and preferably 100 parts by weight or less, more preferably 50 parts by weight or less. When the content of the ester bond-containing polymer is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0108] In the mixture, the content of the compound (Y) relative to 100 parts by weight of the compound (X) is preferably 75 parts by weight or more, more preferably 100 parts by weight or more, even more preferably 200 parts by weight or more, and preferably 10,000 parts by weight or less, more preferably 5,000 parts by weight or less, and even more preferably 2,000 parts by weight or less. When the content of the compound (Y) is not less than the above lower limit and not more than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0109] When the mixture contains the metal catalyst, the content of the metal catalyst in 100% by weight of the mixture is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and preferably 10% by weight or less, more preferably 5% by weight or less. When the content of the metal catalyst is equal to or more than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited.

[0110] When the mixture contains the polymerization inhibitor, the content of the polymerization inhibitor in 100% by weight of the mixture is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, and preferably 0.5% by weight or less, more preferably 0.1% by weight or less. When the content of the polymerization inhibitor is equal to or more than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited.

[0111] <Disassembly process> The decomposition step is a step of decomposing the ester bond-containing polymer. More specifically, the decomposition step is a step of decomposing the ester bond-containing polymer contained in the substance.

[0112] In the decomposition step, the ester bond-containing polymer is preferably decomposed by reacting the ester bond-containing polymer with the compound (X).

[0113] The decomposition step may be carried out substantially simultaneously with the mixing step. For example, by adding the substance to the heated solution (a solution containing the compound (X) and the compound (Y)), the decomposition step proceeds substantially simultaneously with the mixing step.

[0114] In the decomposition step, a transesterification reaction can be allowed to proceed between the ester bond-containing polymer and the compound (X).

[0115] FIG. 1 is a schematic diagram showing the chemical reactions that proceed in the decomposition step in a method for producing a decomposition product of an ester bond-containing polymer according to one embodiment of the present invention. In FIG. 1, a cured unsaturated polyester resin is shown as the ester bond-containing polymer. FIG. 1(a) shows the components before the decomposition step, and FIG. 1(b) shows the components after the decomposition step. FIG. 1(a) shows a cured unsaturated polyester resin made from fumaric acid (F), phthalic acid (P), glycol (G), and styrene (S). Also, FIG. 1(a) shows compound (X) and compound (Y). Also, FIG. 1(a) shows a metal catalyst (C).

[0116] The decomposition products of the ester bond-containing polymer (cured unsaturated polyester resin) decomposed in the decomposition step include the following compounds 1) to 4), as shown in FIG. 1(b), for example.

[0117] 1) Compound (XPX) having a structural portion derived from the above compound (X) on both sides of a structural portion derived from phthalic acid (P).

[0118] The compound (XPX) has double bonds at both ends derived from the double bond of the compound (X). The compound (XPX) is usually a phthalate ester.

[0119] 2) Glycol (G1) (by-product) produced by decomposing ester bond-containing polymers.

[0120] 3) Glycol (G2) (by-product) produced by a side reaction of the above compound (X).

[0121] 4) Compound (XFX) having a structural portion derived from fumaric acid (F) and a structural portion derived from the above compound (X).

[0122] After the decomposition step, unreacted compound (X) also remains in the container. After the decomposition step, compound (Y) also remains in the container. After the decomposition step, metal catalyst (C) and the like also remain in the container.

[0123] In the decomposition step, the mixture is preferably heated, and the decomposition step is preferably a heating reflux step.

[0124] The heating temperature in the decomposition step can be appropriately changed depending on the type of compound (X) and the type of compound (Y).

[0125] In the decomposition step, the ester bond-containing polymer may be decomposed while stirring the mixture.

[0126] The decomposition step may be carried out under normal pressure to low pressure, or under high pressure, such as at normal pressure (0.1 MPa), at normal pressure (0.1 MPa) or higher, at a pressure of 0.2 MPa or higher, at a pressure of 1.0 MPa or higher, at a pressure of 1.0 MPa or lower, or at a pressure of 0.2 MPa or lower.

[0127] When the decomposition step is carried out at a pressure of 0.2 MPa or less (or a pressure less than 0.2 MPa), it is preferable to use the metal catalyst in order to increase the decomposition rate of the ester bond-containing polymer. However, even when the decomposition step is carried out at a pressure of 0.2 MPa or less (or a pressure less than 0.2 MPa), the metal catalyst does not have to be used. Furthermore, when the decomposition step is carried out at a pressure of 0.2 MPa or more (or a pressure exceeding 0.2 MPa), the metal catalyst may or may not be used.

[0128] The present specification also provides a method for decomposing an ester bond-containing polymer, comprising the mixing step and the decomposition step. The method for decomposing an ester bond-containing polymer is preferably a method for decomposing a cured unsaturated polyester resin.

[0129] The relationship between the configuration of the present invention and the effects of the present invention will be explained in more detail below. That is, the reason why the method for producing a decomposition product of an ester bond-containing polymer according to the present invention can obtain a highly reactive decomposition product and suppress the production of glycol as a by-product will be explained below. Note that the following explanation uses a cured unsaturated polyester resin as the ester bond-containing polymer and hydroxyethyl methacrylate as the compound (X), but the effects of the present invention can be achieved by the same action even when a compound other than these compounds is used.

[0130] The chemical reaction formula between the cured unsaturated polyester resin and the compound (X) (hydroxyethyl methacrylate) is shown below.

[0131] [ka]

[0132] The reaction between the cured unsaturated polyester resin and compound (X) produces compound (XPX) and a by-product, glycol (G1). The decomposition product, compound (XPX), has a (meth)acryloyl group and is therefore highly reactive. This (meth)acryloyl group is a structure derived from compound (X). Therefore, by using compound (X), a highly reactive decomposition product can be obtained.

[0133] Furthermore, when compound (X) is used without compound (Y), the equilibrium reaction in the following chemical reaction formula tends to proceed from the left side to the right side, resulting in the production of compound (Y), the reaction product of two molecules of compound (X), and glycol (G2), a by-product. However, as shown in the following chemical reaction formula, this reaction is reversible. Therefore, when compound (Y) is used in addition to compound (X), the equilibrium reaction in the following chemical reaction formula tends to proceed to the left side, suppressing the production of glycol (G2). Furthermore, glycol (G1), which is produced by decomposing the cured unsaturated polyester resin, can also be converted to compound (X) by reacting with compound (Y). These two reactions suppress the production of glycols (G1) and (G2).

[0134] [ka]

[0135] (Method of producing ester bond-containing polymer) The decomposition product of the ester bond-containing polymer obtained by the above-mentioned method for producing a decomposition product of the ester bond-containing polymer can be used to produce (reproduce) the ester bond-containing polymer.

[0136] The method for producing an ester bond-containing polymer of the present invention preferably includes a reaction step of reacting a decomposition product of the ester bond-containing polymer with an alkyd.

[0137] In the method for producing an ester bond-containing polymer of the present invention, the decomposition product of the ester bond-containing polymer includes a decomposition product of the ester bond-containing polymer obtained by the above-mentioned method for producing a decomposition product of the ester bond-containing polymer. The decomposition product may be a decomposition product contained in a filtrate obtained by filtering a liquid after the decomposition step in the above-mentioned method for producing a decomposition product of the ester bond-containing polymer.

[0138] The method for producing an ester bond-containing polymer of the present invention is preferably a method for producing a cured product of an unsaturated polyester resin.

[0139] FIG. 2 is a schematic diagram showing an example of a chemical reaction that proceeds in the reaction step. FIG. 2 is a schematic diagram showing an example of a chemical reaction that proceeds in the reaction step in the manufacturing process of a cured unsaturated polyester resin. In FIG. 2, compound (XPX), compound (X), and compound (Y) shown in FIG. 1(b) are used. FIG. 2(a) shows the components before the reaction step, and FIG. 2(b) shows the cured unsaturated polyester resin obtained after the reaction step. FIG. 2(a) shows compound (XPX). FIG. 2(a) also shows an alkyd made from fumaric acid (F), phthalic acid (P), and glycol (G). FIG. 2(a) also shows compound (X) and compound (Y).

[0140] In the reaction step, the fumaric acid (F) portion of the alkyd is crosslinked by the compound (XPX), by the compound (X), or by the compound (Y), thereby producing a cured unsaturated polyester resin.

[0141] In the reaction step, the above-mentioned crosslinkable monomer such as styrene may be further used, and a curing agent, a curing accelerator, etc. may also be used.

[0142] The present invention will be specifically described below by way of examples and comparative examples, but the present invention is not limited to the following examples.

[0143] The following materials were prepared:

[0144] (Substances containing ester bond-containing polymers) Substance A: Cured unsaturated polyester resin

[0145] (Compound (X)) Hydroxyethyl methacrylate (HEMA)

[0146] (Compound (Y)) Ethylene glycol dimethacrylate (EGDMA)

[0147] (metal catalyst) Tripotassium phosphate (K3PO4)

[0148] (polymerization inhibitor) 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO)

[0149] (Examples 1 and 2 and Comparative Example 1) Mixing process: The components shown in the table below were placed in a container equipped with a mantle heater in the amounts shown in the table below to obtain a mixture (mixed liquid). Note that the components other than the substance containing an ester bond-containing polymer were placed in the container equipped with a mantle heater, and after mixing these components, the substance containing an ester bond-containing polymer was added to the obtained solution.

[0150] Decomposition process: The mantle heater was set to the temperature shown in the table below, and the mixture was heated (refluxed) for the time and pressure shown in the table below. The mixture was stirred during this decomposition process. In this way, the cured unsaturated polyester resin contained in the material reacted with compound (X), and the cured unsaturated polyester resin was decomposed.

[0151] Filtration process: The liquid containing the decomposition products of the cured unsaturated polyester resin was filtered under suction. The filtrate was evaporated under reduced pressure to obtain a liquid containing compound (XPX), which has a structural moiety derived from compound (X) on both sides of a structural moiety derived from phthalic acid (P), compound (X), compound (Y), glycol (G1) produced by decomposition of the cured unsaturated polyester resin, and glycol (G2) produced by a side reaction of compound (X). The chemical structural formula of glycol (G1) is shown in Figure 3(a), and the chemical structural formula of glycol (G2) is shown in Figure 3(c).

[0152] (evaluation) (1) Glycol production inhibition rate The compound (XPX) was removed from the liquid obtained in the filtration step (a liquid containing the compound (XPX), the compound (X), the compound (Y), the glycol (G1), and the glycol (G2)). The liquid from which the compound (XPX) had been removed was dissolved in deuterated chloroform containing 0.03% by weight of tetramethylsilane (TMS), and the resulting liquid was placed in an NMR apparatus. 1 Measurement was performed using H as the measurement nucleus. The measurement was performed 8 times. From the obtained NMR spectrum, the inhibition rates of the production of glycol (G1) and glycol (G2) were calculated according to the following formula.

[0153] Glycol production inhibition rate (%) = {1-(P GA / P TA ) / (P GB / P TB )}×100

[0154] P GA : Glycol peak intensity in the examples P TA : Peak intensity of TMS in the example P GB : Peak intensity of glycol in Comparative Example 1 P TB : Peak intensity of TMS in Comparative Example 1

[0155] (2) Manufacturing (reproduction) of cured unsaturated polyester resin The following experiment was carried out using the resulting mixed solution (M) of the phthalate ester (compound (XPX)), compound (X) and compound (Y).

[0156] (2-1) Experiment using styrene as a cross-linking monomer (conventional method) 55g of crosslinkable monomer (styrene), 45g of alkyd (raw materials: fumaric acid (F), phthalic acid (P), and glycol (G)), 1.0g of curing agent (methyl ethyl ketone peroxide), and 0.5g of curing accelerator (cobalt octylate) were mixed. The crosslinkable monomer (styrene) and alkyd in the resulting mixture were reacted at 20°C. As a result, a cured unsaturated polyester resin was obtained.

[0157] (2-2) Experiment A using styrene, phthalate ester (compound (XPX)), compound (X), and compound (Y) as crosslinkable monomers The crosslinkable monomers in the mixed solution (styrene, compound (XPX), compound (X), compound (Y)) were reacted with alkyd in the same manner as described in "(2-1)" above, except that 27.5 g of styrene and 27.5 g of mixed solution (M) were used as the crosslinkable monomers. As a result, the curing reaction proceeded smoothly, and a cured unsaturated polyester resin was obtained.

[0158] As shown in the above Experiment A, similar to the conventional method, even when a phthalate ester, compound (X), or compound (Y) was used, a good cured unsaturated polyester resin was obtained. Based on the above results, in Table 1 below, "○" is entered as the evaluation result for "Production of cured unsaturated polyester resin" in Examples 1 and 2 and Comparative Example 1.

[0159] The results are shown in Table 1 below and Figure 3. It can be seen that the amount of glycol by-products (glycols (G1), (G2)) produced decreases as the amount of compound (Y) increases. Figure 3(a) shows the chemical structural formula of glycol (G1) obtained in the Examples and Comparative Examples, and Figure 3(c) shows the chemical structural formula of glycol (G2) obtained in the Examples and Comparative Examples. Figures 3(b) and (d) show the chemical structural formula of glycol (G1) obtained in the Examples and Comparative Examples.1 This is a spectrum obtained by H-NMR measurement. Peaks a and b in Figures 3(b) and (d) correspond to the peaks of the structural parts shown in Figures 3(a) and (c). Furthermore, the decomposition product, compound (XPX), contains a (meth)acryloyl group and is a highly reactive compound.

[0160] [Table 1]

Claims

1. a mixing step of obtaining a mixture containing a substance containing an ester bond-containing polymer, compound (X), and compound (Y); a decomposition step of decomposing the ester bond-containing polymer, The compound (X) is a compound having a hydroxyl group and an unsaturated bond (X) different from the double bond contained in the aromatic ring, The compound (Y) is a compound having two or more unsaturated bonds (Y) different from the double bond contained in the aromatic ring, The method for producing a decomposition product of an ester bond-containing polymer, wherein the compound (X) and the compound (Y) are different compounds.

2. the unsaturated bond (X) is an unsaturated bond contained in a (meth)acryloyl group, The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 , wherein the unsaturated bond (Y) is an unsaturated bond contained in a (meth)acryloyl group.

3. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the compound (Y) does not have a hydroxyl group.

4. 3. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the mixing step is a step of mixing a solution containing the compound (X) and the compound (Y) with the substance.

5. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the mixture contains a polymerization inhibitor.

6. 3. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein in the decomposition step, the ester bond-containing polymer is decomposed by reacting the ester bond-containing polymer with the compound (X).

7. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the decomposition step is carried out at a pressure of 0.2 MPa or more.

8. the mixture comprises a metal-based catalyst; The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the metal catalyst is a metal salt, a metal hydroxide, or a metal oxide.

9. the mixture comprises a metal-based catalyst; the metal catalyst is a metal salt, a metal hydroxide, or a metal oxide; The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the decomposition step is carried out at a pressure of 0.2 MPa or less.

10. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the compound (X) is hydroxyethyl methacrylate.

11. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the compound (Y) is ethylene glycol dimethacrylate.

12. The method for producing a decomposition product of an ester bond-containing polymer according to claim 1 or 2, wherein the ester bond-containing polymer is a cured product of an unsaturated polyester resin.

13. The method includes a reaction step of reacting a decomposition product of an ester bond-containing polymer with an alkyd, A method for producing an ester bond-containing polymer, wherein the decomposition product of the ester bond-containing polymer comprises a decomposition product of the ester bond-containing polymer obtained by the method for producing a decomposition product of the ester bond-containing polymer according to claim 1 or 2.

14. The method for producing the ester bond-containing polymer according to claim 13, which is a method for producing a cured product of an unsaturated polyester resin.

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