Production method of decomposed product of unsaturated polyester resin cured product and production method of unsaturated polyester resin cured product

Abstract

To provide a production method of a decomposed product of an unsaturated polyester resin cured product which can simply obtain a decomposed product of an unsaturated polyester resin cured product, and can re-produce an unsaturated polyester resin cured product using the obtained decomposed product.SOLUTION: A production method of a decomposed product of an unsaturated polyester resin cured product includes: a mixing step of obtaining a mixture having a substance containing an unsaturated polyester resin cured product, a compound (X) having an unsaturated bond which has a hydroxyl group and is different from a double bond contained in an aromatic ring, and a metal catalyst; and a decomposition step of reacting the unsaturated polyester resin cured product contained in the substance with the compound (X), and decomposing an unsaturated polyester resin cured product.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a decomposition product of a cured unsaturated polyester resin. The present invention also relates to a method for producing a cured unsaturated polyester resin using the decomposition product obtained by the above-mentioned production method. [Background technology]

[0002] Cured unsaturated polyester resins can be obtained by reacting alkyd with a crosslinkable monomer (e.g., styrene). Cured unsaturated polyester resins are highly durable and are used in a variety of fields. For example, cured unsaturated polyester resins are used as matrix resins for fiber-reinforced plastics. However, recycling technology for cured unsaturated polyester resins has not been put into practical use, and most of them are disposed of by landfill treatment.

[0003] The following Patent Documents 1 and 2 disclose methods for decomposing a cured unsaturated polyester resin.

[0004] Patent Document 1 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 normal pressure but do not put the reaction solvent into a supercritical or subcritical state. In the method of Patent Document 1, no catalyst is used because the depolymerization reaction proceeds with microwaves.

[0005] Patent Document 2 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 from which moisture has been removed and an organic solvent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-110155 A [Patent Document 2] JP 2005-255897 A Summary of the Invention [Problem to be solved by the invention]

[0007] The method described in the above Patent Document 1 requires an apparatus capable of irradiating microwaves, and an apparatus having a large size is required on an industrial scale, so that it is difficult to decompose the cured unsaturated polyester resin easily and the practicality of the method is not necessarily high.

[0008] In the method described in the above Patent Document 2, the decomposition products of the obtained cured unsaturated polyester resin have no reactivity, so that it is difficult to reproduce the cured unsaturated polyester resin using the decomposition products.

[0009] The object of the present invention is to provide a method for producing a decomposition product of a cured unsaturated polyester resin, which can easily obtain a decomposition product of a cured unsaturated polyester resin and can reproduce the cured unsaturated polyester resin using the decomposition product obtained. Another object of the present invention is to provide a method for producing a cured unsaturated polyester resin using the decomposition product obtained by the above-mentioned production method. [Means for solving the problem]

[0010] In this specification, the following method for producing a decomposition product of a cured unsaturated polyester resin and method for producing a cured unsaturated polyester resin are disclosed.

[0011] Item 1. A method for producing a decomposition product of a cured unsaturated polyester resin, comprising: a mixing step of obtaining a mixture containing a substance containing a cured unsaturated polyester resin, a compound (X) having a hydroxyl group and an unsaturated bond different from the double bond contained in an aromatic ring, and a metal catalyst; and a decomposition step of reacting the cured unsaturated polyester resin contained in the substance with the compound (X) to decompose the cured unsaturated polyester resin.

[0012] Item 2. The method for producing a decomposition product of a cured unsaturated polyester resin according to Item 1, wherein the compound (X) has an unsaturated bond at a terminal.

[0013] Item 3. A method for producing a decomposition product of a cured unsaturated polyester resin according to Item 1 or 2, wherein the compound (X) has a structure represented by the following formula (1):

[0014] [ka]

[0015] In the formula (1), R represents a hydrogen atom or a methyl group, and * represents the bonding position to other atoms.

[0016] Item 4. The method for producing a decomposition product of a cured unsaturated polyester resin according to any one of Items 1 to 3, wherein the compound (X) has an allyl group or a (meth)acryloyl group.

[0017] Item 5. The method for producing a decomposition product of a cured unsaturated polyester resin according to any one of Items 1 to 4, wherein the compound (X) is ethylene glycol monoallyl ether, hydroxyethyl methacrylate, or ethylene glycol monoacrylate.

[0018] Item 6. The method for producing a decomposition product of a cured unsaturated polyester resin according to any one of Items 1 to 5, wherein the metal catalyst is a metal salt, a metal hydroxide, or a metal oxide.

[0019] Item 7. The method for producing a decomposition product of a cured unsaturated polyester resin according to any one of Items 1 to 6, wherein the mixture contains a polymerization inhibitor.

[0020] Item 8. The method for producing a decomposition product of a cured unsaturated polyester resin according to any one of Items 1 to 7, wherein the decomposition step is carried out at a pressure of 0.2 MPa or less.

[0021] Item 9. A method for producing a cured unsaturated polyester resin, comprising a reaction step of reacting a decomposition product of a cured unsaturated polyester resin with an alkyd, the decomposition product of the cured unsaturated polyester resin containing a decomposition product of a cured unsaturated polyester resin obtained by a method for producing a decomposition product of a cured unsaturated polyester resin, the method for producing the decomposition product of a cured unsaturated polyester resin being the method for producing a decomposition product of a cured unsaturated polyester resin according to any one of Items 1 to 8.

[0022] Item 10. A method for producing a cured unsaturated polyester resin, comprising a reaction step of reacting a decomposition product of a cured unsaturated polyester resin with a compound (X) having a hydroxyl group and an unsaturated bond different from the double bond contained in an aromatic ring, and an alkyd, wherein the decomposition product of the cured unsaturated polyester resin includes a decomposition product of a cured unsaturated polyester resin obtained by a method for producing a decomposition product of a cured unsaturated polyester resin, the compound (X) includes a compound (X) used in the method for producing a decomposition product of a cured unsaturated polyester resin, and the method for producing the decomposition product of a cured unsaturated polyester resin is the method for producing a decomposition product of a cured unsaturated polyester resin according to any one of Items 1 to 8.

[0023] Item 11. The method for producing a cured unsaturated polyester resin according to Item 9 or 10, wherein the decomposition product of the cured unsaturated polyester resin contains a compound (XPX) having a structural portion derived from the compound (X) on both sides of a structural portion derived from phthalic acid. Effect of the Invention

[0024] The method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention comprises a mixing step of obtaining a mixture containing a substance containing a cured unsaturated polyester resin, a compound (X) having a hydroxyl group and an unsaturated bond different from the double bond contained in the aromatic ring, and a metal catalyst. The method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention comprises a decomposition step of reacting the cured unsaturated polyester resin contained in the substance with the compound (X) to decompose the cured unsaturated polyester resin. Since the method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention has the above-mentioned configuration, it is possible to easily obtain a decomposition product of a cured unsaturated polyester resin, and it is possible to reproduce the cured unsaturated polyester resin using the obtained decomposition product. [Brief description of the drawings]

[0025] [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 a cured unsaturated polyester resin according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a chemical reaction that proceeds in a reaction step in a method for producing a cured unsaturated polyester resin according to one embodiment of the present invention. [Diagram 3] FIG. 3(a) is the chemical structural formula of the compound (XPX) obtained in Example 1, and FIG. 3(b) is the spectrum obtained by 1H-NMR measurement of the compound (XPX) obtained in Example 1. [Figure 4] FIG. 4 is an IR spectrum of the compound (XPX) obtained in Example 1. [Diagram 5] FIG. 5 is an IR spectrum of the cured unsaturated polyester resin used in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The present invention will be described in detail below.

[0027] (Method of producing decomposition product of cured unsaturated polyester resin) The method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention includes a mixing step of obtaining a mixture containing a substance containing a cured unsaturated polyester resin, a compound (X) having a hydroxyl group and an unsaturated bond different from the double bond contained in an aromatic ring, and a metal catalyst.

[0028] The method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention includes a decomposition step of reacting the cured unsaturated polyester resin contained in the substance with the compound (X) to decompose the cured unsaturated polyester resin.

[0029] The method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention has the above-mentioned configuration, and therefore, the decomposition product of a cured unsaturated polyester resin can be easily obtained, and the cured unsaturated polyester resin can be reproduced using the obtained decomposition product.

[0030] In the method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention, the decomposition step can be carried out under normal pressure to low pressure conditions, and therefore, for example, there is no need to use a pressure-resistant container in the decomposition step. In addition, in the method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention, a metal catalyst is used, and therefore, the decomposition step can be carried out without irradiating microwaves. Therefore, the method for producing a decomposition product of a cured unsaturated polyester resin according to the present invention can be carried out on an industrial scale.

[0031] In addition, in the method for producing the decomposition product of the cured unsaturated polyester resin according to the present invention, a specific compound (X) is used, so that the decomposition product obtained contains a reactive decomposition product. Therefore, the cured unsaturated polyester resin can be reproduced by using the decomposition product (reactive decomposition product) or the like. Furthermore, since the compound (X) itself also contributes to the reaction for producing the cured unsaturated polyester resin, the cured unsaturated polyester resin can be reproduced without removing the compound (X) after the decomposition step.

[0032] In the method for producing the decomposition product of the cured unsaturated polyester resin, the mixing step may obtain a mixture containing the substance, the compound (X), the metal catalyst, and a polymerization inhibitor. The mixture may also contain other components.

[0033] First, the components that can be used in the present invention will be described.

[0034] <Substances containing cured unsaturated polyester resin> The above-mentioned substance includes a cured product of an unsaturated polyester resin. The above-mentioned cured product of an unsaturated polyester resin is a cured product of an unsaturated polyester resin. The above-mentioned substance may be used alone or in combination of two or more kinds. The above-mentioned cured product of an unsaturated polyester resin may be used alone or in combination of two or more kinds.

[0035] The unsaturated polyester resin cured product can be obtained, for example, by reacting an alkyd with a crosslinkable monomer. The alkyd can be obtained, for example, by reacting a saturated polybasic acid, an unsaturated polybasic acid, and a polyhydric alcohol.

[0036] 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, etc. The saturated polybasic acid may be used alone or in combination of two or more.

[0037] Examples of the unsaturated polybasic acid include fumaric acid, maleic anhydride, itaconic acid, etc. The unsaturated polybasic acid may be used alone or in combination of two or more kinds.

[0038] Examples of the polyhydric alcohol include glycol and bisphenol. 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 dibromo neopentyl glycol. Examples of the bisphenol include hydrogenated bisphenol A and bisphenol A propylene oxide adduct. The polyhydric alcohol may be used alone or in combination of two or more.

[0039] Examples of the crosslinkable monomer include vinyl monomers, allyl monomers, and acrylic acid esters. Examples of the vinyl monomer include styrene, vinyl toluene, α-methylstyrene, methyl methacrylate, and vinyl acetate. Examples of the allyl monomer include diallyl phthalate, diallyl isophthalate, triallyl isocyanurate, and diallyl tetrabromophthalate. Examples of the acrylic acid ester include phenoxyethyl acrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, and 2-hydroxyethyl acrylate. Only one type of the crosslinkable monomer may be used, or two or more types may be used in combination.

[0040] From the viewpoint of recycling, the above-mentioned substance preferably includes waste containing the above-mentioned cured unsaturated polyester resin. The above-mentioned waste includes waste after using a molded article (product) containing the above-mentioned cured unsaturated polyester resin, and defective products generated during the production of a molded article (product) containing the above-mentioned cured unsaturated polyester resin.

[0041] The substance may contain only the cured unsaturated polyester resin, or may contain the cured unsaturated polyester resin and a component other than the cured unsaturated polyester resin.

[0042] Examples of components other than the cured unsaturated polyester resin include glass fiber, carbon fiber, organic fiber, satin fabric, aramid fiber, boron fiber, silica sand, colorant, calcium carbonate, calcium carbide, talc, aluminum hydroxide, thickener, internal release agent, reactive diluent, low shrinkage agent, antioxidant, modifier, flame retardant, and antibacterial agent. The glass fiber may be contained in the form of a glass mat, a glass cloth, or chopped strands used in sheet molding compound (SMC). Only one of the components may be used, or two or more of them may be used in combination. The material may, for example, contain the cured unsaturated polyester resin and glass fiber, the cured unsaturated polyester resin and silica sand, or the cured unsaturated polyester resin, glass fiber, and silica sand.

[0043] The content of the cured unsaturated polyester resin in 100% by weight of the above 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 cured unsaturated polyester resin in 100% by weight of the above 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.

[0044] <Compound (X)> The compound (X) has a hydroxyl group. The compound (X) has an unsaturated bond different from the double bond contained in the aromatic ring. Hereinafter, in this specification, the "unsaturated bond different from the double bond contained in the aromatic ring" may be referred to as "unsaturated bond (X)". Therefore, 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.

[0045] 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.

[0046] 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.

[0047] The compound (X) may have only one unsaturated bond (X), or may have two, two or more, three, three or more, five or less, four or less, or three or less.

[0048] The unsaturated bond (X) is preferably a double bond. The compound (X) preferably has a double bond.

[0049] 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.

[0050] The compound (X) is preferably a compound having crosslinking reactivity. In this case, a compound capable of reacting with an alkyd is obtained as a decomposition product of the cured unsaturated polyester resin, and the cured unsaturated polyester resin can be successfully reproduced using the decomposition product.

[0051] The compound (X) is preferably a liquid at 20° C. That is, the compound (X) preferably has a melting point below 20° C. and a boiling point above 20° C. In this case, the substance, the compound (X), and the metal catalyst can be mixed well in the mixing step.

[0052] 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, the heating under reflux can be performed well in the decomposition step. The boiling point of the compound (X) may be 300° C. or lower, or 250° C. or lower.

[0053] The compound (X) preferably has an unsaturated bond (unsaturated bond (X)) at the terminal. In this case, a compound capable of reacting with an alkyd is obtained as a decomposition product of the cured unsaturated polyester resin, and the cured unsaturated polyester resin can be successfully reproduced using the decomposition product. When the compound (X) has an unsaturated bond at the terminal, the compound (X) may have an unsaturated bond in a portion other than the terminal, or may have an unsaturated bond only at the terminal.

[0054] The compound (X) preferably has a double bond at the end, and more preferably has a structure represented by the following formula (1). In this case, a compound capable of reacting with an alkyd is obtained as a decomposition product of the cured unsaturated polyester resin, so that the cured unsaturated polyester resin can be successfully reproduced using the decomposition product. The structure represented by the following formula (1) has a double bond at the end.

[0055] [ka]

[0056] In the above formula (1), R represents a hydrogen atom or a methyl group, and * represents the bonding position to other atoms. In the above formula (1), R may be a hydrogen atom or a methyl group.

[0057] 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.

[0058] The compound (X) preferably has an allyl group or a (meth)acryloyl group. In this case, a compound capable of reacting with alkyd is obtained as a decomposition product of the cured unsaturated polyester resin, and the cured unsaturated polyester resin can be successfully reproduced using the decomposition product. The allyl group and the (meth)acryloyl group have a structure represented by the above formula (1). The (meth)acryloyl group is an acryloyl group or a methacryloyl group.

[0059] Examples of the compound (X) having an allyl group include ethylene glycol monoallyl ether (2-allyloxyethanol) and allyl alcohol (2-propen-1-ol).

[0060] 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.

[0061] 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.

[0062] The compound (X) is preferably ethylene glycol monoallyl ether, hydroxyethyl methacrylate, or ethylene glycol monoacrylate, in which case the effects of the present invention can be more effectively exhibited.

[0063] <Metal catalyst> The metal catalyst is a catalyst containing a metal atom. The metal catalyst may be used alone or in combination of two or more kinds.

[0064] The metal catalyst is not particularly limited as long as it can catalyze the chemical reaction between the cured unsaturated polyester resin and the compound (X).

[0065] The metal catalyst includes metal salts, metal hydroxides, metal oxides, and the like.

[0066] 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.

[0067] 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 salts include metal salts containing the above-mentioned metals, and more specifically, examples of the metal salts include tripotassium phosphate and sodium ethoxide.

[0068] 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.

[0069] The metal oxide includes metal oxides containing the above-mentioned metals, and more specifically, copper oxide, titanium dioxide, iron oxide, manganese oxide, vanadium oxide, tin oxide, zinc oxide, aluminum oxide, etc.

[0070] From the viewpoint of further increasing the decomposition efficiency of the cured unsaturated polyester resin material, the metal catalyst is preferably a metal salt, a metal hydroxide or a metal oxide, and more preferably tripotassium phosphate, sodium hydroxide or sodium ethoxide.

[0071] <Polymerization inhibitor> In the mixing step, a polymerization inhibitor may or may not be used. In the mixing step, it is preferable to obtain a mixture containing the substance, the compound (X), the metal catalyst, and 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 kinds.

[0072] 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, copper naphthenate, and 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO).

[0073] <Other ingredients> In the mixing step, other components (components other than the substance, the compound (X), the metal catalyst, and the polymerization inhibitor) may or may not be used. Examples of the other components include crosslinkable monomers and dilution solvents. Only one type of the other components may be used, or two or more types may be used in combination.

[0074] Examples of the crosslinkable monomer include the crosslinkable monomers described in the above section of <Substances containing cured unsaturated polyester resin>. 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, it is preferable to obtain a mixture containing the substance, the compound (X), the metal catalyst, and styrene. In this case, the solubility of the decomposition product obtained after the decomposition step can be increased, and the alkyd can be crosslinked well during the production (reproduction) of the cured unsaturated polyester resin.

[0075] The method for producing the decomposition product of the cured unsaturated polyester resin will now be described in more detail.

[0076] <Mixing process> The mixing step is a step of obtaining a mixture containing the substance, the compound (X), and the metal catalyst. As described above, the mixture may contain the polymerization inhibitor. The mixture may also contain the other components (e.g., styrene).

[0077] The mixing step is carried out, for example, by putting the substance, the compound (X), and the metal catalyst into a container. The mixing step is preferably a step of adding the substance to the compound (X) in the container.

[0078] In the mixture, the substance, the compound (X) and the metal catalyst may or may not be uniformly mixed. For example, in the mixture, the substance may sink to the bottom of the container.

[0079] The substance mixed in the mixing step is preferably a pulverized waste material containing the cured unsaturated polyester resin. In this case, the contact area between the substance and the compound (X) can be increased, so that the decomposition reaction can proceed more efficiently.

[0080] In the mixture, the content of the above substance relative to 100 parts by weight of the compound (X) 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 above 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.

[0081] In the mixture, the content of the cured unsaturated polyester resin in the substance relative to 100 parts by weight of the compound (X) 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 cured unsaturated polyester resin 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.

[0082] In 100% by weight of the mixture, the content of the metal catalyst is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, 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.

[0083] 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.

[0084] <Disassembly process> The decomposition step is a step of reacting the cured unsaturated polyester resin contained in the substance with the compound (X) to decompose the cured unsaturated polyester resin.

[0085] The decomposition step may be carried out substantially simultaneously with the mixing step. For example, the substance is added to the heated compound (X), so that the decomposition step proceeds substantially simultaneously with the mixing step.

[0086] In the decomposition step, a transesterification reaction can be caused to proceed between the cured unsaturated polyester resin and the compound (X).

[0087] FIG. 1 is a schematic diagram showing a chemical reaction that proceeds in a decomposition step in a method for producing a decomposition product of a cured unsaturated polyester resin according to one embodiment of the present invention. FIG. 1(a) shows each component before the decomposition step, and FIG. 1(b) shows each component 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). FIG. 1(a) also shows a compound (X) having a double bond at its terminal. FIG. 1(a) also shows a metal catalyst (C).

[0088] The decomposition product of the cured unsaturated polyester resin decomposed in the decomposition step contains the following compounds 1) to 3), for example, as shown in FIG. 1(b).

[0089] 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).

[0090] 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.

[0091] 2) Glycol (G).

[0092] 3) A compound (XFX) having a structural portion derived from fumaric acid (F), a structural portion derived from styrene (S), and a structural portion derived from the above compound (X).

[0093] After the decomposition step, the unreacted compound (X) also remains in the vessel, and the metal catalyst (C) also remains in the vessel.

[0094] In the decomposition step, the mixture is preferably heated. The decomposition step is preferably a heating reflux step.

[0095] The heating temperature in the above decomposition step can be appropriately changed depending on the type of compound (X).

[0096] In the decomposition step, the cured unsaturated polyester resin may be decomposed while stirring the mixture.

[0097] The decomposition step is preferably carried out at normal pressure (1 atm). However, when it is desired to increase the decomposition rate of the cured unsaturated polyester resin material, the decomposition step may be carried out at a low pressure. The decomposition step is preferably carried out at a pressure of 0.1 MPa or more, and more preferably at a pressure of 0.2 MPa or less. In the present invention, the decomposition reaction can be allowed to proceed even under the above pressure conditions of normal pressure to low pressure. Therefore, there is no need to use a pressure-resistant container or the like, and a decomposition product of the cured unsaturated polyester resin material can be easily obtained.

[0098] The present specification also provides a method for decomposing a cured unsaturated polyester resin material, comprising the above-mentioned mixing step and the above-mentioned decomposition step.

[0099] (Method of producing cured unsaturated polyester resin) The decomposition product of the cured unsaturated polyester resin obtained by the above-mentioned method for producing a decomposition product of the cured unsaturated polyester resin can be used to produce (reproduce) a cured unsaturated polyester resin.

[0100] The method for producing a cured unsaturated polyester resin of the present invention preferably comprises a reaction step of reacting a decomposition product of the cured unsaturated polyester resin with an alkyd. The method for producing a cured unsaturated polyester resin of the present invention preferably comprises a reaction step of reacting a decomposition product of the cured unsaturated polyester resin with an alkyd, a compound (X) having a hydroxyl group and an unsaturated bond different from the double bond contained in the aromatic ring.

[0101] In the method for producing a cured unsaturated polyester resin of the present invention, the decomposition product of the cured unsaturated polyester resin includes the decomposition product of the cured unsaturated polyester resin obtained by the above-mentioned method for producing a decomposition product of a cured unsaturated polyester resin. 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 a cured unsaturated polyester resin.

[0102] In the method for producing a cured unsaturated polyester resin of the present invention, the compound (X) preferably contains the compound (X) used in the method for producing a decomposition product of a cured unsaturated polyester resin described above. The compound (X) may be the compound (X) contained in a filtrate obtained by filtering a liquid after the decomposition step in the method for producing a decomposition product of a cured unsaturated polyester resin described above.

[0103] FIG. 2 is a schematic diagram showing an example of a chemical reaction that proceeds in the reaction process. In FIG. 2, the compound (XPX) and compound (X) shown in FIG. 1(b) are used. In FIG. 2(a), each component before the reaction process is shown, and in FIG. 2(b), the unsaturated polyester resin cured product obtained after the reaction process is shown. In FIG. 2(a), the compound (XPX) is shown. In addition, in FIG. 2(a), an alkyd made from fumaric acid (F), phthalic acid (P), and glycol (G) is shown. In addition, in FIG. 2(a), the compound (X) is shown.

[0104] In the above reaction step, the fumaric acid (F) portion of the alkyd is crosslinked by the above compound (XPX) or by the above compound (X), whereby a cured unsaturated polyester resin can be produced.

[0105] In the reaction step, the above-mentioned crosslinking monomer such as styrene may be further used. That is, the reaction step may be a step of reacting a decomposition product of the cured unsaturated polyester resin with an alkyd and a crosslinking monomer (a crosslinking monomer different from the compound (X)). The reaction step may be a step of reacting a decomposition product of the cured unsaturated polyester resin with the compound (X), an alkyd and a crosslinking monomer (a crosslinking monomer different from the compound (X)).

[0106] In the reaction step, a curing agent, a curing accelerator, etc. may be used. As the curing agent and the curing accelerator, a curing agent and a curing accelerator that are usually used in the curing reaction of an unsaturated polyester resin can be used.

[0107] Since the production efficiency of the cured unsaturated polyester resin can be improved, the decomposition product of the cured unsaturated polyester resin preferably contains a compound (XPX) having a structural portion derived from the compound (X) on both sides of a structural portion derived from phthalic acid (P). The compound (XPX) is preferably a phthalate ester.

[0108] 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.

[0109] The following materials were prepared:

[0110] (Substances containing cured unsaturated polyester resin) Substance A: Unsaturated polyester resin hardened material Substance B: A material containing a cured unsaturated polyester resin and glass fiber (the ratio (weight ratio) of the cured unsaturated polyester resin to components other than the cured product is 7:15 (cured product:components other than the cured product)).

[0111] (Compound (X)) Ethylene glycol monoallyl ether (EGMA) Hydroxyethyl methacrylate (HEMA) Ethylene glycol monoacrylate (HEA)

[0112] (Compound not corresponding to compound (X)) Xylene Ethylene glycol (EG) Diethylene glycol (DEG) Benzyl alcohol (BzOH)

[0113] (Metal catalyst) Potassium phosphate (K3PO4) Sodium Ethoxide (EtONa)

[0114] (Polymerization inhibitor) Phenothiazine 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO)

[0115] (Examples 1 to 9) <Method of manufacturing decomposition product of cured unsaturated polyester resin> 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).

[0116] 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 the decomposition process. In this way, the unsaturated polyester resin cured product contained in the material was reacted with the compound (X) to decompose the unsaturated polyester resin cured product.

[0117] Filtration process: The liquid containing the decomposition product of the cured unsaturated polyester resin was filtered under suction. The filtrate was distilled under reduced pressure to obtain a liquid containing the compound (X) and the compound (XPX) having a structural portion derived from the compound (X) on both sides of a structural portion derived from phthalic acid (P).

[0118] (Comparative Examples 1 to 4) The above mixing step, the above decomposition step, and the above filtration step were carried out in the same manner as in Example 1, except that the components shown in the table below were used and the conditions for the decomposition step were changed as shown in the table below.

[0119] (evaluation) (1) Confirmation of decomposition products (phthalate esters) (1-1) 1 H-NMR measurement From the liquid containing compound (XPX) and compound (X) obtained in the above filtration step, compound (X) was removed to obtain compound (XPX). The obtained compound (XPX) was dissolved in deuterated chloroform, and the liquid was placed in an NMR apparatus. 1The measurement was performed using H as the measurement nucleus. The measurement was accumulated 256 times.

[0120] As a result, it was confirmed that the compounds (XPX) obtained in Examples 1 to 9 were phthalic acid esters having a double bond (C=C) at the terminal. Note that FIG. 3(a) shows the chemical structure of the compound (XPX) obtained in Example 1, and FIG. 3(b) shows the chemical structure of the compound (XPX) obtained in Example 1. 1 The spectrum was obtained by H-NMR measurement. Peaks a to f in Fig. 3(b) correspond to the peaks of the structural portion in Fig. 3(a).

[0121] On the other hand, in Comparative Examples 1 to 4, when the liquid obtained through the above mixing step, the above decomposition step, and the above filtration step was used, a large amount of by-products was produced, and a good spectrum could not be obtained.

[0122] (1-2) IR spectrum measurement Compound (X) was removed from the solution containing compound (XPX) and compound (X) obtained in the above filtration step to obtain compound (XPX). The obtained compound (XPX) was applied to a NaCl plate, which was then placed in an IR device and measured by the transmission method. The measurement range was 4000 cm -1 ~400cm -1 From the obtained IR spectrum, it was confirmed whether or not phthalate esters were produced.

[0123] As a result, it was confirmed that the compounds (XPX) obtained in Examples 1 to 9 were phthalate esters having a double bond (C=C) at the terminal. FIG. 4 shows the IR spectrum of the compound (XPX) obtained in Example 1. In FIG. 4, peak a is a peak derived from the ester bond contained in the compound (XPX), peak b is a peak derived from the double bond (terminal) contained in the compound (XPX), and peak c is a peak derived from the aromatic ring contained in the compound (XPX).

[0124] On the other hand, in Comparative Examples 1 to 4, when the liquid obtained through the mixing step, the decomposition step, and the filtration step was used, a large amount of by-products was produced, and a good IR spectrum could not be obtained.

[0125] (1-3) Decomposition rate of ester bonds The IR spectrum of the cured unsaturated polyester resin was measured in the same manner as described in the above "(1-2) IR spectrum measurement". From the styrene peak in the IR spectrum of the cured unsaturated polyester resin and the styrene peak in the IR spectrum of the compound (XPX) obtained in the above "(1-2) IR spectrum measurement", the decomposition rate of the ester bond in the cured unsaturated polyester resin was calculated by the following formula. Note that FIG. 5 shows the IR spectrum of the cured unsaturated polyester resin (substance A) used in Example 1.

[0126] Decomposition rate of ester bond (%) = (1-P A / P B ) x 100 P A : Intensity of styrene peak of compound (XPX) P B : Styrene peak intensity of cured unsaturated polyester resin

[0127] The results are shown in the following table: In Comparative Examples 2 to 4, the amount of by-products was so large that it was not possible to calculate the decomposition rate of the ester bond.

[0128] (2) Reproduction of hardened unsaturated polyester resin The following experiments were carried out using the compound (XPX) (phthalic acid ester) obtained in Examples 1 to 9. In addition, the following experiments were carried out using the compound (X) obtained in Examples 1 to 9 after the filtration step.

[0129] (2-1) Experiment using styrene as a crosslinking 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 hardener (methyl ethyl ketone peroxide) and 0.5g of hardener accelerator (cobalt octylate) were mixed. The crosslinkable monomer (styrene) and alkyd in the resulting mixture were reacted at 20°C. As a result, a hardened unsaturated polyester resin was obtained.

[0130] (2-2) Experiment A using styrene and compound (XPX) as crosslinking monomers Except for using 27.5g of styrene and 27.5g of compound (XPX) as the crosslinkable monomer, the crosslinkable monomer (styrene and compound (XPX)) in the mixed solution was reacted with alkyd in the same manner as described in the above "(2-1)". As a result, the curing reaction proceeded well, and a cured unsaturated polyester resin was obtained.

[0131] (2-3) Experiment B using compound (XPX) as a crosslinking monomer The crosslinkable monomer (compound (XPX)) in the mixed solution was reacted with the alkyd in the same manner as described in the above "(2-1)" except that 55 g of compound (XPX) was used as the crosslinkable monomer and the reaction temperature was changed to 80° C. As a result, the curing reaction proceeded smoothly, and a cured unsaturated polyester resin was obtained.

[0132] (2-4) Experiment C using styrene and compound (X) as crosslinking monomers Except for using 27.5g of styrene and 27.5g of compound (X) as the crosslinkable monomer, the crosslinkable monomer (styrene and compound (X)) in the mixed solution was reacted with alkyd in the same manner as described in the above "(2-1)". As a result, the curing reaction proceeded well, and a cured unsaturated polyester resin was obtained.

[0133] (2-5) Experiment D using compound (X) as a crosslinking monomer The crosslinkable monomer (compound (X)) in the mixed solution was reacted with the alkyd in the same manner as in the method described in "(2-1)" above, except that 55 g of compound (X) was used as the crosslinkable monomer and the reaction temperature was changed to 60° C. As a result, the curing reaction proceeded smoothly, and a cured unsaturated polyester resin was obtained.

[0134] (2-6) Experiment E using compound (XPX), compound (X), and styrene as crosslinkable monomers Except for using 4 g of compound (XPX), 11 g of compound (X) and 40 g of styrene as crosslinkable monomers, the crosslinkable monomers (compound (XPX), compound (X) and styrene) in the mixed solution were reacted with alkyd in the same manner as described in "(2-1)" above. As a result, the curing reaction proceeded well, and a cured unsaturated polyester resin was obtained.

[0135] (2-7) Experiment F using compound (XPX) as a crosslinking monomer Except for using 55 g of compound (XPX) as the crosslinkable monomer, the crosslinkable monomer (compound (XPX)) in the mixed solution was reacted with alkyd in the same manner as described in the above "(2-1)". As a result, the curing reaction proceeded smoothly, and a cured unsaturated polyester resin was obtained.

[0136] (2-8) Experiment G using compound (XPX), compound (X), and styrene as crosslinkable monomers Except for using 7.5 g of compound (XPX), 20 g of compound (X) and 27.5 g of styrene as crosslinkable monomers, the crosslinkable monomers (compound (XPX), compound (X) and styrene) in the mixed solution were reacted with alkyd in the same manner as described in "(2-1)" above. As a result, the curing reaction proceeded well, and a cured unsaturated polyester resin was obtained.

[0137] (2-9) Experiment H using compound (XPX), compound (X), and styrene as crosslinkable monomers Except for using 15 g of compound (XPX) and 40 g of compound (X) as crosslinkable monomers, the crosslinkable monomers (compound (XPX), compound (X) and styrene) in the mixed solution were reacted with alkyd in the same manner as described in "(2-1)" above. As a result, the curing reaction proceeded well, and a cured unsaturated polyester resin was obtained.

[0138] As shown in the above experiments A to H, the unsaturated polyester resin cured material was obtained well even when the compound (XPX) or the compound (X) was used, as in the conventional method. Therefore, the unsaturated polyester resin cured material can be reproduced.

[0139] Details and results are shown in Tables 1 to 3 below.

[0140] [Table 1]

[0141] [Table 2]

[0142] [Table 3]

Claims

1. a mixing step of obtaining a mixture containing a substance containing a cured unsaturated polyester resin, a compound (X) having a hydroxyl group and an unsaturated bond other than the double bond contained in an aromatic ring, and a metal catalyst; and a decomposition step of reacting the cured unsaturated polyester resin contained in the substance with the compound (X) to decompose the cured unsaturated polyester resin.

2. The method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1, wherein the compound (X) has an unsaturated bond at a terminal thereof.

3. The method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2, wherein the compound (X) has a structure represented by the following formula (1): 【Chemistry 1】 In the formula (1), R represents a hydrogen atom or a methyl group, and * represents the bonding position to other atoms.

4. The method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2, wherein the compound (X) has an allyl group or a (meth)acryloyl group.

5. The method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2, wherein the compound (X) is ethylene glycol monoallyl ether, hydroxyethyl methacrylate, or ethylene glycol monoacrylate.

6. The method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2, wherein the metal catalyst is a metal salt, a metal hydroxide, or a metal oxide.

7. The method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2, wherein the mixture contains a polymerization inhibitor.

8. The method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2, wherein the decomposition step is carried out at a pressure of 0.2 MPa or less.

9. The method includes a reaction step of reacting a decomposition product of a cured unsaturated polyester resin with an alkyd, the decomposition product of the cured unsaturated polyester resin includes a decomposition product of the cured unsaturated polyester resin obtained by a method for producing a decomposition product of the cured unsaturated polyester resin, The method for producing a decomposition product of a cured unsaturated polyester resin, comprising the method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2.

10. The method includes a reaction step of reacting a decomposition product of a cured unsaturated polyester resin with a compound (X) having a hydroxyl group and an unsaturated bond other than the double bond contained in an aromatic ring, and an alkyd, the decomposition product of the cured unsaturated polyester resin includes a decomposition product of the cured unsaturated polyester resin obtained by a method for producing a decomposition product of the cured unsaturated polyester resin, the compound (X) includes the compound (X) used in the method for producing a decomposition product of a cured unsaturated polyester resin, The method for producing a decomposition product of a cured unsaturated polyester resin, comprising the method for producing a decomposition product of a cured unsaturated polyester resin according to claim 1 or 2.

11. The method for producing a cured unsaturated polyester resin according to claim 9, wherein the decomposition product of the cured unsaturated polyester resin contains a compound (XPX) having a structural portion derived from the compound (X) on both sides of a structural portion derived from phthalic acid.

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