Chemical recycling methods for engineering plastics

Abstract

This invention relates to (-CH2O-) n The objective is to provide a method for decomposing resins, including their structures, and a method for recycling them. [Solution] The present invention relates to (-CH2O-) n A resin containing a structure (where n is a positive integer indicating the degree of polymerization), Alcohol or water, A process of treatment in the presence of a polymer acid catalyst. The present invention provides a method for decomposing the aforementioned resin, including the above.

Description

[Technical Field]

[0001] This invention relates to a method for chemically recycling engineering plastics. [Background technology]

[0002] To mitigate environmental damage and make efficient use of resources, it is necessary to recycle plastic waste. In recent years, chemical recycling, which involves breaking down plastic waste to the level of raw materials such as monomers for reuse, and upcycling, which involves synthesizing various useful compounds using the monomers obtained from the decomposition, have been proposed. While the widespread adoption of chemical recycling and upcycling is crucial for promoting plastic waste recycling, it cannot be said that they are currently sufficiently widespread.

[0003] Polyacetal resin (also known as polyoxymethylene resin, abbreviated as POM resin) is an engineering plastic with a chemical structure in which methylene groups (CH2) and oxygen (O) are arranged alternately and regularly. Due to this regularly arranged chemical structure, it is easy to form a crystalline structure and is characterized by a high degree of crystallinity. POM resin has well-balanced mechanical properties and excellent friction and wear resistance, chemical resistance, heat resistance, and electrical properties, and is therefore widely used in various fields such as automobiles and electrical and electronic products.

[0004] As a chemical recycling method for POM resin, for example, Non-Patent Document 1 proposes a method of decomposing POM resin using bismuth(III) trifluoromethanesulfonate as a catalyst to obtain cyclic acetals. Non-Patent Document 2 proposes a method of decomposing POM resin using a Mn pincer-type complex as a catalyst to obtain methanol. Non-Patent Document 3 proposes a method of decomposing POM resin using H-montmorillonite as a catalyst to obtain cyclic acetals. However, recycling technology for POM resin is still not sufficiently developed, and further technological development is needed. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Klankermayer Chem Sus Chem 2020, 13, 488-492. [Non-Patent Document 2] Milstein J. Am. Chem. Soc. 2024, 146, 22017-22026. [Non-Patent Document 3] Mizugaki, 134th Catalytic Symposium: September, 2024, Nagoya, 2E04 [Overview of the project] [Problems that the invention aims to solve]

[0006] In view of the above circumstances, the present invention relates to POM resin, i.e., (-CH2O-) n The objective is to provide a method for decomposing and recycling a resin containing a structure (where n is a positive integer indicating the degree of polymerization). [Means for solving the problem]

[0007] The inventors diligently studied to solve the above problem. That is, (-CH2O-) n Various methods were investigated to decompose and recycle resins containing structures, and it was found that using a polymer acid catalyst, (-CH2O-) n We discovered that resins containing structures can be decomposed, and the decomposed materials can be recycled. Based on this discovery, the present invention was completed.

[0008] In other words, the gist of this invention is as follows: [1] (-CH2O-) n A resin containing a structure (where n is a positive integer indicating the degree of polymerization), Alcohol or water, A process of treatment in the presence of a polymer acid catalyst. A method for decomposing the resin, comprising the above. [2] The method according to [1], wherein the resin is (-CH2O-) n A polyacetal block copolymer comprising a structure and a polymer portion of a structural unit other than (-CH2O-). [3] The method according to [1], wherein the resin is a polyacetal homopolymer. [4] The method according to any one of [1] to [3], wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and two or more hydroxyl groups. [5] The method according to any one of [1] to [3], wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and two hydroxyl groups. [6] The method according to any one of [1] to [5], wherein the polymeric acid catalyst is a resin having an acidic group. [7] The method according to any one of [1] to [6], wherein the polymeric acid catalyst is a resin having a benzenesulfonic acid group. [8] The method according to any one of [1] to [7], wherein the polymeric acid catalyst is a meta-phenolsulfonic acid-based resin comprising a structural unit represented by the following formula (I).

[0009]

Chemical Formula

[0010] [9] The method according to any one of [1] to [7], wherein the polymeric acid catalyst is a phenyl-para-styrenesulfonic acid-based resin comprising at least one of a structural unit represented by the following formula (II) and a structural unit represented by the following formula (III).

[0011]

Chemical Formula

[0012] [ka]

[0013]

[10] The method according to any one of [1] to [9], wherein the resin is a fiber-reinforced resin.

[11] The method according to any one of [1] to

[10] , wherein the above step is performed under microwave irradiation.

[12] (-CH2O-) n A resin containing a structure (where n is a positive integer indicating the degree of polymerization), Alcohol and, A process of treatment in the presence of a polymer acid catalyst. A method for producing acetal compounds, including those mentioned above.

[13] The aforementioned resin is (-CH2O-) n The method according to

[12] , which is a polyacetal block copolymer containing the structure and polymerized portions of structural units other than (-CH2O-).

[14] The method according to

[12] , wherein the resin is a polyacetal homopolymer.

[15] The method according to any one of

[12] to

[14] , wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and having two or more hydroxyl groups.

[16] The method according to any one of

[12] to

[14] , wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and having two hydroxyl groups.

[17] The method according to any one of

[12] to

[16] , wherein the polymer acid catalyst is a resin having an acidic group.

[18] The method according to any one of

[12] to

[17] , wherein the polymer acid catalyst is a resin having a benzenesulfonic acid group.

[19] The method according to any one of

[12] to

[18] , wherein the polymer acid catalyst is a meta-phenol sulfonic acid resin comprising a structural unit represented by the following formula (I).

[0014]

Chemical Formula

[0015]

[20] The method according to any one of

[12] to

[18] , wherein the polymer acid catalyst is a phenyl-para-styrene sulfonic acid resin comprising at least one of a structural unit represented by the following formula (II) and a structural unit represented by the following formula (III).

[0016]

Chemical Formula

[0017]

Chemical Formula

[0018]

[21] The method according to any one of

[12] to

[20] , wherein the step is performed under microwave irradiation.

[22] A method for upcycling said resin, comprising the method according to any one of [1] to

[21] .

Effects of the Invention

[0019] According to the present invention, (-CH2O-) n a method for decomposing a resin containing the structure and recovering it as a useful substance is provided. That is, according to the present invention, (-CH2O-) n chemical recycling of a resin containing the structure is possible. Further, upcycling for synthesizing a new compound by using a monomer or the like obtained by decomposing the resin can be performed.

Brief Description of Drawings

[0020] [Figure 1] Figure 1 is a diagram (photograph) showing the reaction in Example 2-1. [Figure 2] Figure 2 is a diagram (photograph) showing the reaction in Example 2-2. [Figure 3] Figure 3 shows the effects of various polymer acid catalysts on the decomposition of POM resin. [Figure 4] Figure 4 shows the effect of polymer catalysts on the decomposition of various POM products. [Figure 5] Figure 5 shows the effect of polymer catalysts on the decomposition of various POM products. [Figure 6] Figure 6 shows the effect of polymer catalysts on the decomposition of fiber-reinforced POM. [Modes for carrying out the invention]

[0021] The following is a definition of the terms used in this specification.

[0022] In this specification, "resin" primarily refers to synthetic resins, and unless otherwise specified, it refers to high-molecular-weight compounds including (co)polymers (polymers) formed by the polymerization of monomers. A polymer is a high-molecular-weight compound in which one or more types of "constitutional units" are linked together. A low-molecular-weight compound before the repeating units are incorporated into the polymer is called a "monomer."

[0023] In this specification, "phenolsulfonic acid-based resin" means a resin having a benzene ring in which one to three sulfonic acid groups and one to three hydroxyl groups are substituted within the molecules constituting the resin, and includes "resins containing phenolsulfonic acid-formaldehyde polycondensates," etc.

[0024] In this specification, unless otherwise specified, "meta-phenolsulfonic acid-based resin" means a resin having a benzene ring in which sulfonic acid groups and hydroxyl groups are meta-substituted within the molecules constituting the resin, and includes "resins containing meta-phenolsulfonic acid-formaldehyde polycondensates," etc.

[0025] In this specification, "phenolsulfonic acids" means, unless otherwise specified, phenolsulfonic acids (without any particular limitations on the number or substitution positions of hydroxyl and sulfonyl groups), phenolsulfonic acid derivatives (meaning phenols having other substituents along with the sulfonic acid group), and their metal salts (meaning a group of compounds in which the sulfonic acid group forms a salt with a metal ion).

[0026] In this specification, "formaldehydes" refers to formaldehyde, its aqueous solutions (e.g., formalin), and polymers (including anhydrous trioxane and paraformaldehyde).

[0027] The embodiments of the present invention will be described in detail below. <Disassembly method> One aspect of the present invention is (-CH2O-) n A resin containing a structure (where n is a positive integer indicating the degree of polymerization), Alcohol or water, A process of treatment in the presence of a polymer acid catalyst. This invention relates to a method for decomposing the resin, including (hereinafter sometimes referred to as "the decomposition method of the present invention").

[0028] The inventors of this invention have identified POM resin, i.e., (-CH2O-) n In an investigation into various methods for decomposing resins containing structures, we found that using a polymer acid catalyst, (-CH2O-) n We discovered that resins containing structures can be decomposed. In addition, we found that acetal compounds are obtained as decomposition products when treated in the presence of alcohol. In the decomposition method of the present invention, (-CH2O-) n It is possible to decompose the resin containing the structure and recover it as useful substances such as acetal compounds.

[0029] ≪(-CH2O-) n Resins including structure≫ (-CH2O-) is the target of the decomposition method of the present invention. nAs for resins containing the structure, (-CH2O-) n There are no particular restrictions as long as the resin contains a structure. Here, n is a positive integer indicating the degree of polymerization, and is a positive integer of 2 or more, preferably 10 or more, more preferably 30 or more, even more preferably 50 or more, and even more preferably 100 or more, with no particular upper limit. More specifically, (-CH2O-) n The resin containing the structure only needs to contain an oxymethylene group (-CH2O-) in its molecule, preferably a polymer compound in which the oxymethylene group (-CH2O-) is the main constituent unit (for example, more than 50%, 70% or more, 80% or more, 90% or more, 95% or more, or 97% or more of the total constituent units of the polymer), and includes polyacetal homopolymers consisting substantially only of repeating oxymethylene units, and polyacetal copolymers containing oxymethylene units and other structural units (for example, (-C2H5O-), etc.). Examples of polyacetal copolymers include block copolymers having polymeric moieties consisting of repeating oxymethylene groups and other polymeric moieties. The other structural units may be one or more types.

[0030] The decomposition method of the present invention may target the resin itself, or a resin composition containing additional components other than the resin. Examples of additional components other than the resin included in the resin composition include heat stabilizers, formic acid scavengers, weather-resistant stabilizers, mold release agents, lubricants, conductive agents, (-C H2O-) n Examples of resins other than those containing structures, thermoplastic resins, dyes and pigments, pigments, inorganic fillers, organic fillers, fibers, etc., may include one or more of these. As resin compositions, fiber-reinforced resins, in particular, which have fibers incorporated into the resin to improve strength, are used in various applications because they can form lightweight and high-strength molded articles. The decomposition method of the present invention can also be preferably used for fiber-reinforced resins. The fibers used in fiber-reinforced resins are not particularly limited and may be those commonly used in the field, such as glass fibers or carbon fibers.

[0031] Alcohol and water The alcohol used in the decomposition method of the present invention is not particularly limited, but examples include C1-C10 alkyl compounds having one hydroxyl group (monohydric alcohols) and C2-C10 alkyl compounds having two or more hydroxyl groups (polyhydric alcohols). Examples of monohydric alcohols include C1-C10, C1-C5, or C1-C3 linear or branched alcohols, and examples of polyhydric alcohols include C2-C10, C2-C6, or C2-C3 linear or branched dihydric and trihydric alcohols. Dihydric alcohols are preferred. These alcohols may also be primary, secondary, or tertiary alcohols. More specifically, examples include monohydric alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 2-methyl-1-propanol; 1,2-Ethanediol (ethylene glycol), 1,2-Propanediol (propylene glycol), 1,3-Propanediol, 1,2-Butanediol, 1,3-Butanediol, 1,4-Butanediol, 1,2-Pentanediol, 1,5-Pentanediol, 1,2-Hexanediol, 1,6-Hexanediol, 1,2-Heptanediol, 1,1,2,2-Tetramethyl-1,2-Ethanediol, 1-Me Dihydric alcohols (glycols) such as ethyl-1,3-propanediol, 1,3-dimethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, and 1,2-octanediol; Trihydric alcohols such as glycerin; Examples include the following. These alcohols may have substituents such as alkyl, alkenyl, cycloalkyl, aryl, heteroaryl, alkoxy, nitro, cyano, and halogen. One of these alcohols may be used, or two or more may be used in combination.

[0032] The alcohol used in the decomposition method of the present invention can be one synthesized by known synthesis methods or one that is commercially available.

[0033] The decomposition method of the present invention can also use water.

[0034] From the perspective of obtaining high decomposition efficiency, (-CH2O-) n The reaction ratio (molar ratio) between the resin containing the structure and the alcohol or water is usually in the range of 1:10 to 10:1, preferably 1:1 to 1:2. However, the alcohol or water is not limited to the above range and can be used in large excess amounts as a solvent.

[0035] ≪Polymer acid catalyst≫ The polymer acid catalyst used in the present invention is not particularly limited as long as it exhibits the above-mentioned effects, but examples include resins having acidic groups. Examples of resins having acidic groups include sulfonic acid resins, carboxylic acid resins, phosphoric acid resins, phenolic acid resins, boronic acid resins, etc. More specifically, even if they have substituents such as hydroxyl groups, Examples of resins with good benzenesulfonic acid groups include phenolsulfonic acid resins, among which phenolsulfonic acid resins are preferred. Note that one type of acid catalyst may be used, or two or more types may be used in combination.

[0036] The resin having the above-mentioned acidic group is a solid catalyst and can be preferably used from the viewpoint of operability (separation, recovery, reuse, etc.). Furthermore, the catalyst has an acidic group and is hydrophilic, and (-CH2O-) n Because it has high affinity for resins containing the structure, as well as for alcohol and water, it can be preferably used from the viewpoint of improving reactivity.

[0037] The polymer acid catalyst used in the present invention can be synthesized by known synthesis methods or a commercially available product. Examples of commercially available products include PAFR-II (meth-phenolsulfonic acid-formaldehyde resin; Fujifilm Wako Pure Chemical Corporation).

[0038] A preferred form of the polymer acid catalyst used in the present invention is, for example, described in WO2019 / 203241. The listed meta-phenolsulfonic acid resin, preferably meta-phenolsulfonic acid-phenolsulfonic acid Examples include resins containing aldehyde polycondensates. More specifically, examples include resins containing structural units represented by the following general formula (I), preferably resins containing repeating structures of structural units represented by the following general formula (I). Examples of such resins include novolac-type resins and resol-type resins, with novolac-type resins being particularly preferred.

[0039] [ka]

[0040] A preferred form of the polymer acid catalyst used in the present invention is, for example, the form described in Sakaguchi, T. and Hashimoto, T., “Synthesis of poly(diphenylacetylene)s bearing various polar groups and their gas permeability”, Polymer Journal, 46, 391-398 (2014). Examples include phenyl-para-styrene sulfonic acid resins. More specifically, resins containing at least one of the structural units represented by the following general formula (II) and the following formula (III), preferably resins containing at least one of a repeating structure of the structural units represented by the following general formula (II) and the following formula (III).

[0041] [ka]

[0042] [ka]

[0043] The polymer acid catalyst used in the present invention may, in addition to the resin having the above-mentioned acidic group, optionally contain known thickeners, reinforcing materials, additives, etc., to form a catalyst composition.

[0044] There are no particular restrictions on the amount of polymer acid catalyst used in the reaction, and it can be appropriately selected depending on the purpose. However, the molar ratio of the resin to be decomposed to the catalyst is usually in the range of 1:0.00001 to 1:5, preferably 1:0.00005 to 1:0.2.

[0045] The decomposition method of the present invention involves the above polymer acid catalyst, (-CH2O-) n This can be achieved by mixing a resin containing the structure with alcohol or water and subjecting it to a decomposition reaction. A polymer acid catalyst, (-CH2O-) is used during mixing. n The order in which the resin containing the structure and the alcohol or water are added does not matter. The decomposition method of the present invention can also be carried out under microwave irradiation. Microwave irradiation is not limited, but may be performed using a microwave generator with a frequency of 2.4 GHz and a microwave output of 0 to 2000 W, for example, at a maximum output of 10 to 1000 W, 30 to 300 W, or 50 to 150 W. Microwave irradiation can accelerate the decomposition reaction.

[0046] The reaction temperature in the above decomposition reaction can be appropriately selected considering the composition of the reaction solution and the heat resistance temperature of the catalyst, but is usually room temperature to 180°C, 50 to 160°C, or 80 to 150°C. A higher reaction temperature results in a faster and more efficient reaction, while a lower temperature slows down the catalyst degradation rate, allowing the reaction to be carried out continuously for a longer period. The reaction time is not particularly limited and can be appropriately selected considering the yield of the reactants, but is typically set within the range of 0.5 to 72 hours.

[0047] The above decomposition reaction does not necessarily require the use of a solvent, but one may be used if necessary. Suitable solvents are those that form a homogeneous phase with the polymer acid catalyst and alcohol or water used in the reaction, such as hydrocarbons, ethers, and esters.

[0048] The above decomposition reaction produces (-CH2O-) n Useful substances such as acetal compounds and formaldehyde can be obtained from resins containing the structure. For example, when 1,3-propanediol is used as the alcohol, 1,3-dioxane is produced, and when ethanol is used, The mixture produces diethoxymethane, which is useful as a solvent, etc. After the decomposition reaction, the product can be isolated and purified by known isolation and purification methods, such as filtration, concentration, extraction, distillation, sublimation, recrystallization, column chromatography, and other common operations, if desired.

[0049] Furthermore, the catalyst can be easily separated from the reaction mixture by known methods such as filtration and washing, and reused. The catalyst of the present invention is a catalyst with high reusability. Here, high reusability means, but is not limited to, that the activity after 5 reuses is 85% or more, 90% or more, 95% or more, 97% or more, and 98% or more, compared to the activity after the first use. Reusability can be determined by known methods, for example, the method described in the examples below.

[0050] <Manufacturing method> Another aspect of the present invention is (-CH2O-) n A resin containing a structure (where n is a positive integer indicating the degree of polymerization), Alcohol or water, A process of treatment in the presence of a polymer acid catalyst. This invention relates to a method for producing acetal compounds or formaldehydes, including the present invention (hereinafter sometimes referred to as "the production method of the present invention").

[0051] Furthermore, all matters described in the section on <Decomposition Method> above apply to the description of the manufacturing method of the present invention. That is, in the manufacturing method of the present invention, (-CH2O-) n The resin containing the structure, alcohol or water, polymer acid catalyst, and processing conditions are the same as those described in the <Decomposition Method> section above, and you can refer to the explanation in the <Decomposition Method> section above.

[0052] In the production method of the present invention, a polymer acid catalyst is used to produce (-CH2O-) n The resin containing the structure is decomposed into monomers, etc., which react with alcohol or water to produce acetal compounds or formaldehydes. The following are examples of the manufacturing method of the present invention, although these are not limited to the present invention. (1)(-CH2O-) n A process of treating a resin containing a structure, such as POM resin, in the presence of an alkyl compound (polyhydric alcohol) having 2 or more hydroxyl groups and having 2 to 10 carbon atoms, and a polymer acid catalyst. A method for producing cyclic acetal compounds, including those mentioned above. (2)(-CH2O-) n A resin containing a structure, such as POM resin, is treated in the presence of an alkyl compound (monohydric alcohol) having 1 to 10 carbon atoms and one hydroxyl group, and a polymer acid catalyst. The process, A method for producing acetal compounds, including those mentioned above. (3)(-CH2O-) n A process of treating a resin containing a structure, such as POM resin, in the presence of water and a polymer acid catalyst. A method for producing formaldehydes, including [the specified substance].

[0053] <Upcycling Methods> Another aspect of the present invention is (-CH2O-) n A resin containing a structure (where n is a positive integer indicating the degree of polymerization) Alcohol or water, A process of treatment in the presence of a polymer acid catalyst. This invention relates to a method for upcycling the aforementioned resin, including (hereinafter sometimes referred to as "the upcycling method of the present invention").

[0054] The upcycling method of the present invention is the method described above for both the <disassembly method> and the <manufacturing method>. It is the same. That is, (-CH2O-) manufactured as plastic. n A resin containing a structure (where n is a positive integer indicating the degree of polymerization) (e.g., POM resin), alcohol and polymer By treating the material in the presence of an acid catalyst, acetal compounds useful as solvents can be produced. Formaldehyde compounds can also be recovered by using water instead of alcohol. Furthermore, by adding auxiliary raw materials such as amine compounds during the above process, the compounds can be converted into useful compounds having a hemiaminal structure. Specifically, the upcycling method of the present invention can be used, for example, in the synthesis of the active ingredient of the insecticide shown in the example (synthesis of chlorfenapyr). Furthermore, the matters described in the sections on <Decomposition Method> and <Manufacturing Method> above all apply to the description of the upcycling method of the present invention. That is, (-CH2O-) n The resin containing the structure, alcohol or water, polymer acid catalyst, processing conditions, etc., are the same as those described in the <Decomposition Method> and <Manufacturing Method> above, and the matters described in the <Decomposition Method> and <Manufacturing Method> sections can be referenced.

[0055] The plastic used above is the aforementioned (-CH2O-) n The plastic is not particularly limited as long as it is made of resin including a structure, and may be molded, colored, or otherwise processed. The auxiliary materials used in the above are not particularly limited, and there are no particular restrictions as long as they can synthesize the target compound and react with the monomers of the decomposed resin. There are no particular restrictions on the amount of the above auxiliary materials used in the reaction, and they can be appropriately selected according to the purpose, but the molar ratio of the resin to be decomposed to the auxiliary materials is usually in the range of 1:10 to 10:1, preferably 1:2 to 1:5. [Examples]

[0056] The present invention will be specifically described below with reference to examples, but these are merely illustrative examples of the present invention, and the scope of the present invention is not limited thereto.

[0057] PAFR-II: Metaphenolsulfonic acid-formaldehyde polycondensation resin

[0058] <Example 1-1> Upcycling of POM Plastic

[0059] [ka]

[0060] A mixture of POM 1 (400 mg, 13.3 mmol, 1 mol equiv), 1,3-propanediol 2a (15.96 mmol, 1.2 mol equiv), and PAFR-II (260 mol ppm, 1.1 mg) was placed in a 10 mL microwave reaction test tube and attached to a microwave reactor. The microwave reactor was set to a maximum power of 80. The reaction temperature was set to 130°C (monitored with an IR thermometer). The reaction time was 2 hours. It was within the time frame. After the reaction was complete, the reaction tube was returned to room temperature and dissolved in deuterated chloroform. Using 1,3,5-trimethoxybenzene as an internal standard, 1 The formation of 3a was confirmed by 1H NMR, GC, and GC-MS measurements. The reaction was confirmed, and the yield was determined. Similarly, the reaction was carried out using dialcohols 2b-f (2b: 1,3-butanediol, 2c: 2,4-pentanediol, 2d: ethylene glycol, 2e: 2,3-dimethyl-2,3-butanediol, 2f: 1,4-butanediol).

[0061] As a result, the POM resin was decomposed, and reaction products 3a-f were obtained in the following yields.

[0062] [ka]

[0063] <Examples 1-2> Reusability of catalysts The recovery and reuse of the catalyst were tested. The experiment was carried out as follows: After the reaction in Example 1-1, the solid catalyst was filtered out and dissolved in water (20 mL), methanol (20 mL), and diethyl ether (10 mL). The catalysts were washed sequentially. The catalysts were collected and dried under reduced pressure for 16 hours. The dried catalysts were then used in the next reaction.

[0064] The results are shown in Table 1. In other words, the yield was maintained even after 6 reuses.

[0065] [Table 1]

[0066] <Example 2-1> Reaction on a large scale (5 grams) Using a black POM joint (5g, 166.66 mol equiv), 1,3-propanediol 2a (199.99 mmol, 1.2 mol equiv), and PAFR-II (260 mol ppm, 12.5 mg), the reaction was carried out in a 35 mL reaction tube with the microwave power set to a maximum of 150 W and the reaction time set to 12 hours, in the same manner as in Example 1-1 above.

[0067] As a result, the POM resin was decomposed, and 1,3-dioxane was obtained in a yield of 89% (Figure 1).

[0068] <Example 2-2> From carbon fiber reinforced plastics (CFRP) Upcycling Using 400 mg of carbon fiber reinforced POM (POM-10-C) (containing 90 wt% (360 mg) of POM in 400 mg of POM-10-C, 12.00 mol equiv), 1,3-propanediol 2a (14.4 mmol, 1.2 mol equiv), and PAFR-II (260 mol ppm, 1.0 mg), the reaction was carried out in a 35 mL reaction tube for 6 hours. The reaction was carried out in the same manner as in Example 1-1 described above.

[0069] As a result, the POM resin was decomposed, and 1,3-dioxane was obtained in a yield of 71% (Figure 2). Furthermore, the yield improved to 78% when the reaction was carried out at 140°C for 6 hours.

[0070] <Example 3> Reaction using ethanol, methanol, and water

[0071] [ka]

[0072] The above reaction was carried out using ethanol, methanol, and water.

[0073] As a result, when ethanol and methanol were used, the reaction proceeded and the POM resin decomposed. Then, reaction products were obtained (Equation 1 and Equation 2 above). The reaction proceeds even when water is used, the POM resin is decomposed, and formaldehyde is produced as a reaction product. It was thought that this would be produced. Therefore, by adding acetophenone 5, the resulting hormone was produced. Maldehyde and acetophenone undergo an aldol reaction, yielding the corresponding compounds 6 and 7 (Equation 3 above).

[0074] <Example 4> Synthesis of insecticide from POM

[0075] [ka]

[0076] The above reaction was carried out using ethanol and compound 18 as a secondary raw material.

[0077] As a result, by adding compound 18 as a secondary raw material, the POM resin is decomposed, and the reaction is Product 19 was obtained (using Equation 1 above). Furthermore, stepwise one-pot synthesis also decomposes the POM resin, and Product 19 was obtained (Equation 2 above).

[0078] <Example 5> Investigation of polymer acid catalysts

[0079] [ka]

[0080] The above reaction was carried out using various polymer acid catalysts.

[0081] The results are shown in Figure 3. POM resin was decomposed using various polymer acid catalysts, and reaction products were obtained. In particular, a 99% yield was achieved with PAFR-II. The strength of the acid affects the yield, but appropriate... A certain level of acidity is considered necessary.

[0082] <Example 6> Upcycling of POM Plastic

[0083] [ka]

[0084] [ka]

[0085] Substrate 21a was treated with NiCl2·6H2O (0.25 mol%) catalyst, PhB(OH)2 (1.5 eq.), MeCN / H2O (20:1). The mixture was then polymerized by reacting it under air at 100°C for 24 hours to obtain polymer 22a (yield 90%, Mw=75,504). Next, 22a was treated with (CH3CO)2O / H2SO4 in CHCl3 and reacted under air at 24°C for 3 hours to sulfonate it, obtaining catalyst 22b in 70% yield. Similarly, the reaction was carried out using B2(OH)4 (0.66 equivalents) instead of PhB(OH)2 (1.5 equivalents) to obtain catalyst 22b' in 55% yield.

[0086] [ka]

[0087] [ka]

[0088] A mixture of plastic (983 mg), diol 23 (1.2 equivalents), and catalyst 22b (0.5 mg) was placed in a 10 mL test tube for microwave reaction and attached to a microwave reactor. The oscillator was set to a maximum output of 80W, and the reaction temperature was set to 130°C (monitored with an IR thermometer). The reaction time was 24 hours. After the reaction was complete, the reaction tube was returned to room temperature and dissolved in deuterated chloroform. Using 1,3,5-trimethoxybenzene as an internal standard, 1 1H NMR, GC, and GC-MS measurements The formation of 24 was confirmed by a controlled reaction, and the yield was found to be 95%. Similarly, the reaction was carried out using catalyst 22b' instead of catalyst 22b, and the formation of 24 was confirmed, with a yield of 74%.

[0089] [ka]

[0090] The above reaction was carried out using various POM products and fiber-reinforced POM.

[0091] The results for various POM products are shown in Figures 4 and 5, and the results for fiber-reinforced POM are shown in Figure 6. Using catalyst 22b, various POM products and fiber-reinforced POM were decomposed, and reaction products were obtained.

[0092] <Consideration> As described above, (-CH2O-) n It has been revealed that by treating a resin containing a specific structure in the presence of alcohol or water and a polymeric acid catalyst, the resin can be decomposed, and new compounds can be synthesized using the resulting monomers. [Industrial applicability]

[0093] According to the present invention, POM resin, an engineering plastic, can be efficiently decomposed and regenerated into new compounds, enabling chemical recycling of various products. It is useful in that context.

Claims

1. (-CH ２ O-) ｎ A resin containing a structure (where n is a positive integer indicating the degree of polymerization), Alcohol or water, A process of treatment in the presence of a polymer acid catalyst. A method for decomposing the resin, including the following.

2. The aforementioned resin is (-CH ２ O-) ｎ Structure, and (-CH ２ The method according to claim 1, wherein the polyacetal block copolymer includes polymer portions of structural units other than O-).

3. The method according to claim 1, wherein the resin is a polyacetal homopolymer.

4. The method according to claim 1, wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and having two or more hydroxyl groups.

5. The method according to claim 1, wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and having two hydroxyl groups.

6. The method according to claim 1, wherein the polymer acid catalyst is a resin having an acidic group.

7. The method according to claim 1, wherein the polymer acid catalyst is a resin having a benzenesulfonic acid group.

8. The method according to claim 1, wherein the polymer acid catalyst is a metaphenolsulfonic acid resin containing a structural unit represented by the following formula (I). 【Chemistry 1】

9. The method according to claim 1, wherein the polymer acid catalyst is a phenyl-para-styrene sulfonic acid resin containing at least one of the structural units represented by the following formula (II) and the structural units represented by the following formula (III). 【Chemistry 2】 【Transformation 3】

10. The method according to claim 1, wherein the resin is a fiber-reinforced resin.

11. The method according to claim 1, wherein the above step is performed under microwave irradiation.

12. (-CH ２ O-) ｎ A resin containing a structure (where n is a positive integer indicating the degree of polymerization), Alcohol and, A process of treatment in the presence of a polymer acid catalyst. A method for producing acetal compounds, including those mentioned above.

13. The resin is (-CH ２ O-) ｎ structure, and (-CH ２ is a polyacetal block copolymer comprising a polymer portion of structural units other than O-), the method according to claim 12.

14. The method according to claim 12, wherein the resin is a polyacetal homopolymer.

15. The method according to claim 12, wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and having two or more hydroxyl groups.

16. The method according to claim 12, wherein the alcohol is an alkyl compound having 2 to 10 carbon atoms and having two hydroxyl groups.

17. The method according to claim 12, wherein the polymer acid catalyst is a resin having an acidic group.

18. The method according to claim 12, wherein the polymer acid catalyst is a resin having a benzenesulfonic acid group.

19. The method according to claim 12, wherein the polymer acid catalyst is a metaphenolsulfonic acid resin containing a structural unit represented by the following formula (I). 【Chemistry 4】

20. The method according to claim 12, wherein the polymer acid catalyst is a phenyl-para-styrene sulfonic acid resin containing at least one of the structural units represented by the following formula (II) and the structural units represented by the following formula (III). 【Transformation 5】 【Transformation 6】

21. The method according to claim 12, wherein the above step is performed under microwave irradiation.

22. A method for upcycling a resin, comprising the method according to any one of claims 1 to 21.

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