JP2024045015A - A method for decomposing a polymer compound, a degradable adhesive composition and a method for separating a bonded body using the same, a degradable paint composition and a method for removing a coating film using the same, and a method for removing fibers contained in fiber-reinforced plastics. How to collect - Google Patents

Abstract

[Problem] To provide a method for decomposing poly(diacylhydrazine) by dry treatment using a reactive gas, and further application means for poly(diacylhydrazine) using the same. [Solution] A polymer compound having a divalent group represented by the following chemical formula (1), i.e., poly(diacylhydrazine), can be decomposed and reduced in molecular weight by contacting the polymer compound with nitrogen oxide. Since the nitrogen oxide used in this case is a gas, this decomposition method is a dry treatment. In the above chemical formula (1), bonds marked with wavy lines represent bonds to other atoms. TIFF2024045015000023.tif18154 [Selected Figure] None

Description

Application for application of Article 30, Paragraph 2 of the Patent Act Publication name: Proceedings of the 103rd Spring Annual Meeting of the Chemical Society of Japan, page K301-3am-08, Publisher: The Chemical Society of Japan, Public Interest Incorporated Association, Publication date: March 8, 2020 Meeting name: 103rd Spring Annual Meeting of the Chemical Society of Japan, Organizer: The Chemical Society of Japan, Public Interest Incorporated Association, Date: March 24, 2020

The present invention relates to a method for decomposing a polymer compound, a method for separating a degradable adhesive composition and its joined body, a method for removing a degradable paint composition and its coating film, and a method for recovering fibers contained in fiber-reinforced plastics. It is something.

In recent years, from the perspective of environmental protection, there has been active development of degradable polymer materials, such as biodegradable polymers and photodegradable polymers, which naturally decompose even when discarded. . However, a problem with biodegradable polymers and photodegradable polymers is that they deteriorate over time in normal usage environments.

For this reason, there is a need for polymer compounds that do not deteriorate over time during use and can be quickly decomposed when disposed of.Dicarboxylic acids or their reactive derivatives are suitable as polymer compounds that can be easily decomposed by oxidizing agents during disposal. Several examples of poly(diacylhydrazine) obtained by polycondensing (acid chloride or active ester derivative) with hydrazine or dihydrazide of a dicarboxylic acid have been proposed (see, for example, Patent Documents 1 and 2).

This poly(diacylhydrazine) can be easily decomposed by oxidizing agents as mentioned above, so it can not only solve the waste problem of plastic products, but also can be applied to adhesive compositions, for example. By using an oxidizing agent, it becomes an adhesive composition that can easily release the bonded state, and when applied to a paint composition, it can be used to create a paint that allows the paint film to be easily peeled off by using an oxidizing agent. It is expected that it will become a composition.

Japanese Patent Application Publication No. 2006-022315 JP 2011-052075 A

As described above, the application of the property of poly(diacylhydrazine) being easily decomposed by an oxidizing agent is expected to lead to the development of various products. Meanwhile, as described in the above patent document, poly(diacylhydrazine) is not decomposed by radical oxidizing agents such as oxygen molecules, but is easily decomposed by oxidizing agents such as sodium hypochlorite. Many of these oxidizing agents exhibit an oxidizing effect in the form of an aqueous solution, and therefore, when attempting to decompose poly(diacylhydrazine) with an oxidizing agent, a wet treatment using the aqueous solution must be performed. However, there may be cases where the application destination of poly(diacylhydrazine) does not like the use of water. Therefore, if a means for decomposing poly(diacylhydrazine) can be provided not only by the above-mentioned wet treatment but also by a dry treatment using a reactive gas, its uses can be further expanded.

The present invention has been made in view of the above circumstances, and aims to provide a method for decomposing poly(diacylhydrazine) by dry treatment using a reactive gas, and further application means of poly(diacylhydrazine) using the method. In this specification, poly(diacylhydrazine) refers to a compound having multiple divalent groups (diacylhydrazine structures) represented by the following chemical formula (1), and does not necessarily mean only compounds containing the divalent group represented by the following chemical formula (1) as a repeating structure.

As a result of extensive research into solving the above problems, the inventors discovered that a polymer compound having a divalent group represented by the following chemical formula (1), i.e., poly(diacylhydrazine), can be easily decomposed by contacting it with nitrogen oxides, and thus completed the present invention. Specifically, the present invention provides the following:

（上記化学式（１）において、波線を付した結合は、他の原子への結合手を表す。） (1) The present invention is a method for decomposing a polymer compound, comprising the step of contacting nitrogen oxides with a polymer compound having a divalent group represented by the following chemical formula (1):

(In the above chemical formula (1), the bond with a wavy line represents a bond to another atom.)

(2) The present invention also relates to a method for decomposing a polymer compound according to item (1), in which the polymer compound is at least one selected from the group consisting of a cured product of an epoxy resin, a crosslinked product of a vinyl polymer, and a polyurethane.

（上記化学式（１）において、波線を付した結合は、他の原子への結合手を表す。） (3) The present invention also relates to a decomposable adhesive composition which contains a polymer compound having a divalent group represented by the following chemical formula (1) and which decomposes upon contact with nitrogen oxides.

(In the above chemical formula (1), the bond with a wavy line represents a bond to another atom.)

(4) The present invention provides a bonded body bonded by a cured product of the degradable adhesive composition described in item (3) above, which is characterized in that the cured product is brought into contact with nitrogen oxide. It is also a separation method.

（上記化学式（１）において、波線を付した結合は、他の原子への結合手を表す。） (5) The present invention provides a degradable paint composition characterized by containing a polymer compound having a divalent group represented by the following chemical formula (1), and decomposed by contacting with nitrogen oxides. There is also.

(In the chemical formula (1) above, the bond with a wavy line represents a bond to another atom.)

(6) The present invention also relates to a method for removing a coating film from a painted surface, characterized by contacting a painted surface having a coating film formed from the decomposable coating composition described in (5) above with nitrogen oxides.

（上記化学式（１）において、波線を付した結合は、他の原子への結合手を表す。） (7) The present invention decomposes the matrix by bringing nitrogen oxide into contact with a fiber-reinforced plastic containing a polymer compound having a divalent group represented by the following chemical formula (1) as a matrix. It is also a method for recovering fibers contained in fiber-reinforced plastics, which is characterized by separating and recovering the fibers contained therein.

(In the chemical formula (1) above, the bond with a wavy line represents a bond to another atom.)

According to the present invention, a method for decomposing poly(diacylhydrazine) by dry treatment using a reactive gas, and further application means for poly(diacylhydrazine) using the method are provided.

Hereinafter, one embodiment of the method for decomposing a polymer compound of the present invention, one embodiment of the degradable adhesive composition, one embodiment of the method for separating a joined body using the same, and one embodiment of the degradable paint composition. , a method for removing a coating film using the same, and a method for recovering fibers contained in fiber-reinforced plastics will be described. Note that the present invention is not limited to the following embodiments and embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

<Method for Decomposing Polymer Compound>
First, one embodiment of the method for decomposing a polymer compound of the present invention will be described. The method for decomposing a polymer compound of the present invention is characterized by including a step of contacting a polymer compound having a divalent group represented by the following chemical formula (1) with nitrogen oxide. In the following chemical formula (1), the bond with a wavy line represents a bond to another atom. In addition, a polymer compound "having a divalent group represented by the following chemical formula (1)" means a compound containing a structure represented by the following chemical formula (1) in the molecule of the polymer compound.

When a polymer compound has the structure represented by the above chemical formula (1), it decomposes through the following chemical reaction when it comes into contact with nitrogen oxides. In the chemical reaction below, an example is shown in which the polymer compound is decomposed by nitric oxide and nitrogen dioxide, but as shown in the chemical reaction formula below, the decomposition reaction is triggered by the nitrosation of the nitrogen atom contained in the structure represented by the above chemical formula (1), and there are no particular limitations on the nitrogen oxide that can cause such nitrosation.

As shown in the above chemical reaction formula, the polymer compound having the structure represented by chemical formula (1) is nitrosated by contacting with nitrogen oxide. By undergoing this nitrosation, the part surrounded by the broken line above becomes an excellent leaving group, and water molecules present in the environment attack the carbonyl group adjacent to this leaving group, causing the leaving group to leave. The molecule is cleaved. Thereafter, the eliminated compound is converted to azide by dehydration. Through these reactions, the polymer compound is decomposed and its molecular weight is reduced.

The polymer compound to be decomposed is not particularly limited as long as it has the structure represented by the above chemical formula (1). The structure represented by the above chemical formula (1) may be included in the main chain of the polymer compound as a repeating unit, in the side chain of the polymer compound, or in a crosslinked structure that crosslinks polymer chains. Examples of such polymer compounds include cured epoxy resins, crosslinked vinyl polymers, and polyurethanes. In addition, cured epoxy resins and crosslinked vinyl polymers are cured products with extremely large molecular weights, in which multiple polymer chains are crosslinked. Strictly speaking, such cured products may not be called polymer compounds, but in the present invention, polymer compounds including such cured products are called polymer compounds.

The cured epoxy resin is obtained by curing an epoxy resin containing a polyepoxy compound, a polyol compound, and a curing catalyst such as an amine. The cured epoxy resin in the present invention has a structure represented by the above chemical formula (1) in its molecule. In many epoxy resins, a bisphenol compound such as bisphenol A is used as a polyol compound. By using such a bisphenol compound, for example, a compound obtained by the following synthetic route, the structure represented by the above chemical formula (1) can be introduced into the polymer compound, which is the cured epoxy resin. Note that, for the sake of explanation, four types of bisphenol compounds are given below as examples, but the present invention is not limited to these.

To synthesize a polyphenol compound such as a bisphenol compound, a phenol carboxylic acid hydrazide is synthesized as described above, and then oxidatively condensed using an oxidizing agent such as bisacetoxyiodobenzene. Other examples of the oxidizing agent used here include potassium hydrogen persulfate, potassium hydrogen sulfate, and potassium sulfate double salts, bis(trifluoroacetoxy)iodobenzene, and iodosobenzene.

The bisphenol compound having a divalent group represented by the chemical formula (1) obtained by the above procedure is reacted with a polyepoxy compound as described below in the presence of a base catalyst such as imidazole. harden.

The main chain of the polymer compound that is cured by reacting as shown in the chemical reaction formula above contains a divalent group represented by the chemical formula (1) above, and as already explained, it can be brought into contact with nitrogen oxides. The bond between (C=O)-NH is broken and decomposed, resulting in a lower molecular weight. When the molecular weight of the cured product is reduced in this way, it becomes very brittle and can be easily removed.

A crosslinked vinyl polymer can be obtained, for example, by radical polymerization of (A) a monomer having an ethylenically unsaturated bond and (B) a crosslinking agent having two or more ethylenically unsaturated bonds and a divalent group represented by the above chemical formula (1) in the molecule. Such a crosslinking agent can be obtained, for example, by reacting (meth)acryloyl chloride with hydrazine in the presence of a base, as shown in the following chemical reaction formula. In this specification, (meth)acryloyl means acryloyl and/or methacryloyl.

The crosslinking agent obtained as described above is polymerized together with a monomer having an ethylenically unsaturated bond (for example, a vinyl monomer) in the presence of a polymerization initiator such as azobisisobutyronitrile (AIBN). to form a crosslinked vinyl polymer. This crosslinked product has a divalent group represented by the above chemical formula (1) in the crosslinked portion, and the crosslinked portion is cut by contacting with nitrogen oxide.

Monomers with ethylenically unsaturated bonds include ethylene, styrene, acrylic acid, acrylic esters, methacrylic esters, acrylamide, N-substituted acrylamide, N,N-disubstituted acrylamide, acrylonitrile, butadiene, vinyl acetate, etc. can be mentioned.

Polymerization initiators include those that generate radicals when heated, such as persulfates, such as sodium persulfate, potassium persulfate, and ammonium persulfate; peroxides, such as hydrogen peroxide, t-butyl peroxide, and methyl ethyl ketone peroxide; and azo compounds, such as azonitrile compounds, azoamidine compounds, cyclic azoamidine compounds, azoamide compounds, alkylazo compounds, 2,2'-azobis(2-amidinopropane) dihydrochloride, and 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride.

Polyurethane is a polymer compound synthesized by a polycondensation reaction between a diisocyanate compound and a diol compound. By using a diol compound having the structure represented by the above chemical formula (1), a polyurethane having the structure represented by the above chemical formula (1) can be obtained. Such a diol compound can be synthesized, for example, by an oxidative condensation reaction of a carboxylic acid hydrazide of an alcohol, in the same manner as the bisphenol compound having the structure of chemical formula (1). Note that, like the carboxylic acid hydrazide of phenol, the carboxylic acid hydrazide of alcohol can be easily synthesized by esterifying the carboxylic acid of alcohol and then reacting it with hydrazine. As the alcohol carboxylic acid used in this synthesis, many compounds such as glycolic acid, lactic acid, tartaric acid, and citric acid are known, and these can be used without restriction.

Examples of nitrogen oxides used to decompose polymer compounds include nitric oxide, nitrogen dioxide, nitrogen trioxide, nitrous oxide, dinitrogen trioxide, dinitrogen tetroxide, dinitrogen pentoxide, etc., and among these, nitric oxide and nitrogen dioxide are preferred. These nitrogen oxides are contacted in a gaseous state with the polymer compound to be decomposed. For this reason, the decomposition method of the present invention can be carried out by a dry process, not a wet process using an aqueous solution of hypochlorite as in the above patent document, and can be applied without problems even when the decomposition target is an object that dislikes water. One example of such an application is as an underfill when mounting a BGA (ball grid array) chip on an electric circuit board. When a BGA chip is mounted on an electric circuit board, due to the difference in thermal expansion coefficient between the chip and the electric circuit board, when a thermal load is applied during a reflow process or the like when mounting elements on the board, the terminals of the BGA chip may shift from the pads of the electric circuit board, resulting in poor electrical connection. In order to repair such a defect or for other reasons, the chip fixed by the underfill may be removed and remounted on the board. In such cases, the underfill can be easily removed by a dry process in which it is exposed to nitrogen oxide gas.

Polymer compounds decomposed by nitrogen oxides become very brittle and can be easily removed. Therefore, if the polymer compound is used as an adhesive, it can be easily removed from the object to be bonded, and if it forms a coating, it can be easily removed from the painted surface.

<Degradable adhesive composition>
Next, the degradable adhesive composition of the present invention will be explained. The degradable adhesive composition of the present invention is characterized by containing a polymer compound having a divalent group represented by the following chemical formula (1), and is characterized by being decomposed by contacting with nitrogen oxides. In addition, in chemical formula (1), a bond with a wavy line represents a bond to another atom.

That is, the degradable adhesive composition of the present invention contains the polymer compound described in the above method for decomposing a polymer compound of the present invention. Therefore, the cured product formed from this adhesive composition contains the above-mentioned polymer compound, and when brought into contact with nitrogen oxides, it decomposes and becomes lower in molecular weight. The cured product that has been decomposed and reduced in molecular weight has lost its robustness as a cured product and is extremely brittle and can be easily removed. Note that the nitrogen oxides are as described above in the decomposition method of the present invention, so the explanation here will be omitted.

The degradable adhesive composition of the present invention may be a type of composition that contains the above-mentioned polymer compound and a solvent and becomes a cured product of the polymer compound when the solvent evaporates, or it may be a composition that contains a precursor of the above-mentioned polymer compound and that becomes a cured product of the polymer compound when the solvent evaporates. It may be a type of composition that becomes a cured product upon reaction. An example of the latter type of composition is a so-called epoxy adhesive composition containing a polyepoxy compound, a polyol compound, and a curing catalyst such as an amine, or a monomer having (A) an ethylenically unsaturated bond; B) A vinyl adhesive composition containing a crosslinking agent having two or more ethylenically unsaturated bonds and having a divalent group represented by the above chemical formula (1) in the molecule, and (C) a polymerization initiator. can be mentioned. Note that the degradable adhesive composition of the present invention is not limited to these.

The epoxy adhesive composition contains a polyepoxy compound, a polyol compound, and a curing catalyst such as an amine, and provides a polymer compound having a divalent group represented by the above chemical formula (1) as a cured product. Since there are many commercially available polyepoxy compounds for use in epoxy adhesive compositions, they can be obtained and used. Further, as the polyol compound, a bisphenol compound having a divalent group represented by the chemical formula (1) as described above can be preferably mentioned. Preferred examples of the amine compound as a curing catalyst include imidazole and the like. It has already been explained that these components react to give a cured product that becomes a polymer compound with a divalent group represented by the chemical formula (1), and that it decomposes when it comes into contact with nitrogen oxides. As this is true, we will omit the explanation here.

The vinyl adhesive composition includes (A) a monomer having an ethylenically unsaturated bond, (B) two or more ethylenically unsaturated bonds having a divalent group represented by the above chemical formula (1) in the molecule. and (C) a polymerization initiator, and provides a polymer compound having a divalent group represented by the above chemical formula (1) as a cured product thereof. Since each of these components has already been described in the description of the crosslinked vinyl polymer, the description thereof will be omitted here. Further, as already mentioned, this cured product has the structure represented by the above chemical formula (1), and decomposes when it comes into contact with nitrogen oxides.

<Method of disassembling the joined body>
The present invention also provides a method for separating a bonded structure bonded with the cured product of the decomposable adhesive composition, the method comprising contacting the cured product with nitrogen oxide. This has already been described in the description of the decomposable adhesive composition, and therefore will not be described here.

<Degradable coating composition>
Next, the decomposable adhesive composition of the present invention will be described. The decomposable coating composition of the present invention is characterized by containing a polymer compound having a divalent group represented by the following chemical formula (1), and by the fact that the coating film thereof decomposes upon contact with nitrogen oxides. In addition, in chemical formula (1), the bond with a wavy line represents a bond to another atom.

That is, the decomposable coating composition of the present invention contains the polymer compound described in the above-mentioned method for decomposing a polymer compound of the present invention. In this decomposable coating composition, the polymer compound is a component that functions as a binder for forming a coating film. Therefore, the coating film formed by this coating composition is decomposed and reduced in molecular weight when contacted with nitrogen oxides. The decomposition and reduction in molecular weight of the binder that forms the coating film makes the coating film brittle, making it easier to remove from the painted surface. Note that nitrogen oxides are as described in the above-mentioned method for decomposing the coating film of the present invention, so a description thereof will be omitted here.

The decomposable coating composition of the present invention contains the above-mentioned polymer compound as a binder, a pigment, and a solvent, and when the solvent evaporates, the polymer compound forms a coating film. As already explained, when this polymer compound comes into contact with nitrogen oxides, it decomposes and becomes a low molecular weight compound.

<How to remove paint film from painted surface>
Another aspect of the present invention is a method for removing a paint film from a painted surface, which comprises bringing nitrogen oxide into contact with a painted surface provided with a paint film formed from the above-mentioned decomposable paint composition. Since this has already been described in the description of the decomposable adhesive composition, the explanation here will be omitted.

<Method for recovering fibers contained in fiber-reinforced plastics>
Next, a method for recovering fibers contained in a fiber-reinforced plastic of the present invention will be described. The method for recovering fibers contained in a fiber-reinforced plastic of the present invention is characterized in that a fiber-reinforced plastic containing a polymer compound having a divalent group represented by the following chemical formula (1) as a matrix is contacted with nitrogen oxide to decompose the matrix, and the fibers contained in the fiber-reinforced plastic are separated and recovered. In addition, in chemical formula (1), bonds marked with wavy lines represent bonds to other atoms.

Fiber reinforced plastics (hereafter referred to as FRP) are composite materials that have been strengthened by combining lightweight plastics, which have a low elastic modulus and low strength, with reinforcing materials such as glass fiber or carbon fiber, which have a high elastic modulus and high tensile strength, and exhibit good mechanical properties. As such, they are used in a wide range of fields, including transportation equipment, housing equipment, pools, and building materials. In particular, carbon fiber reinforced plastics (hereafter referred to as CFRP), which use carbon fiber as a reinforcing material, are lightweight and have strength comparable to that of steel, and are widely used as a material to replace the steel plates that have traditionally been used in automobiles, aircraft, etc.

However, due to its excellent durability and strength, FRP tends to cause waste disposal problems. In addition, while the carbon fibers used in CFRP have excellent properties, they are very expensive. If it were possible to recover and reuse carbon fibers from discarded CFRP, it would be very useful in terms of both the environment and cost. The present invention responds to such demands, and by contacting nitrogen oxide with FRP containing a polymer compound having a divalent group represented by the above chemical formula (1) as a matrix, the polymer compound matrix is decomposed and reduced in molecular weight. The reduced molecular weight matrix can be easily disintegrated, making it possible to easily extract the fibers contained in the matrix.

FRP is generally made by impregnating fibers such as glass fibers or carbon fibers with a matrix material, molding this into a desired shape, and then curing it. Examples of such fibers include glass fibers, carbon fibers, aramid fibers, etc. Among these, carbon fibers are preferred. Examples of these fibers include unidirectional materials in which fibers are arranged in one direction, woven materials such as plain weave, twill weave, and satin weave, and nonwoven materials.

The polymer compound constituting the matrix is not limited as long as it has a divalent group represented by the above chemical formula (1). Preferred examples of such polymer compounds include cured products of epoxy resins and crosslinked products of vinyl polymers. FRP with these as a matrix exhibits sufficient durability during use, but after use, the matrix can be easily removed by contacting with nitrogen oxide.

A cured epoxy resin is made by curing an epoxy resin that contains a polyepoxy compound, a polyol compound, and a curing catalyst such as an amine. The fibers are impregnated with this uncured epoxy resin, and then the epoxy resin is cured to produce FRP.

For example, in ordinary epoxy resins, bisphenol compounds such as bisphenol A are used as polyol compounds, but by introducing a divalent group represented by the above chemical formula (1) into the molecules of such bisphenol compounds. I would like to mention that. As such a polyol compound, those described in the explanation of the method for decomposing a polymer compound of the present invention can be used.

The crosslinked vinyl polymer is obtained by radical polymerization of (A) a monomer having an ethylenically unsaturated bond and (B) a crosslinking agent having two or more ethylenically unsaturated bonds and a divalent group represented by the above chemical formula (1) in the molecule. These (A) and (B) are mixed with a radical polymerization initiator to prepare a liquid polymerizable composition, which is then impregnated into fibers and heated to harden the polymerizable composition, thereby forming an FRP. As for these (A), (B) and radical polymerization initiator, those described above in the description of the method for decomposing a polymer compound of the present invention can be used.

EXAMPLES Hereinafter, the present invention will be explained in more detail by showing Examples, but the present invention is not limited to the following Examples.

・Verification using model compounds

First, a model compound 1 having a diacylhydrazine moiety (a divalent group represented by the above chemical formula (1)) was used to investigate the product produced when nitrogen oxide was brought into contact with the model compound 1. 10 mL of concentrated sulfuric acid was added little by little to 6.911 g (0.1002 mol) of sodium nitrite, and the generated gas mixture of nitrogen monoxide and nitrogen dioxide was passed through an anhydrous calcium chloride tube using an argon stream to form compound 1 (0.0309 g, 0.1029 mmol) for 20 minutes. When the obtained product was developed by thin layer chromatography, the spot of compound 1 disappeared, and spots corresponding to two types of compounds were newly confirmed. When these compounds were confirmed by ¹ H-NMR spectrum and IR spectrum, they were confirmed to be compounds 2 and 3. From this, it was confirmed that the compound having the divalent group represented by the above chemical formula (1) decomposes when brought into contact with nitrogen oxide.

・Synthesis of diacryloylhydrazine 4

20 g (0.4 mol) of hydrazine monohydrate and 40 g (1 mol) of sodium hydroxide were dissolved in 400 mL of water, and in this solution, 80 g (0.88 mol) of acrylic acid chloride was dissolved in 100 mL of tetrahydrofuran at 0°C. The solution was added dropwise over 30 minutes. The precipitated crystals were collected by filtration and washed with a small amount of cold water. The filtrate was extracted with ethyl acetate using a continuous extraction device, and crystals were also precipitated from this extract. The obtained crystals were combined and vacuum dried to obtain 40 g (yield 70%) of diacryloylhydrazine 4 as colorless crystals.

Preparation of acrylic cured material and its decomposition reaction A polymerizable composition was prepared by mixing N,N-dimethylacrylamide (DMA), diacryloylhydrazine 4 synthesized by the above procedure, and 2,2'-azobisisobutyronitrile (AIBN) in a molar ratio of 95:5:2. This polymerizable composition was applied to a substrate and then heated at 100°C to form a cured film on the substrate. When the obtained cured film was contacted with a mixture of nitric oxide and nitrogen dioxide prepared by the same procedure as above for 20 minutes, the cured film became brittle and was broken into pieces by the application of even a small force.

・Preparation of epoxy cured product, its decomposition, and its decomposition reaction 1,2-bis[3-(4-hydroxyphenyl)propanyl] shown by the following chemical formula according to the procedures in paragraphs 0054 to 0057 of JP2011-236381A Hydrosin (compound 5) was obtained.

An epoxy resin composition was prepared by mixing 50 parts by mass of bisphenol A type epoxy resin (Epon 828, Shell, epoxy equivalent 184-194), 50 parts by mass of bisphenol F type epoxy resin (830LVP, Dainippon Ink & Chemicals, epoxy equivalent 163), 80 parts by mass of compound 5, 5 parts by mass of imidazole, 3 parts by mass of silica filler (Silica Aerosil R972, Nippon Aerosil), 2 parts by mass of a thixotropic agent (steric acid amide), and 1 part by mass of a silicone coupling agent (KBM803, Shin-Etsu Chemical Co., Ltd.). This epoxy resin composition was applied to a substrate and then heated at 180°C to form a cured film on the substrate. The obtained cured film was contacted with a mixture of nitric oxide and nitrogen dioxide prepared by the same procedure as above for 20 minutes, and the cured film became brittle and was broken into pieces by applying only a small force.

As shown above, it can be seen that the polymer compound having a divalent group represented by the above chemical formula (1), i.e., poly(diacylhydrazine), decomposes when contacted with nitrogen oxides, becoming easily removable.

・Synthesis of polydiacylhydrazine

Add terephthalic acid chloride 7 (2.03 g, 10.0 mmol) to a solution of dihydrazide 6 (2.50 g, 10.0 mmol) in dimethylformamide (DMF; 10 mL), cover with a stopper to prevent exposure to air, and stir for 2 hours. did. The resulting solution was diluted by adding DMF (40 mL), poured into methanol (500 mL) with vigorous stirring, the resulting precipitate was filtered, washed well with methanol, and dried under vacuum to obtain polydiacylhydrazine 8. Ta.

- Decomposition of polydiacylhydrazine A mixture of nitrogen monoxide and nitrogen dioxide prepared in the same manner as above was brought into contact with the powder of polydiacylhydrazine 8 for 1 hour. The product was apparently unchanged but completely dissolved in methanol. Since polydiacylhydrazine 8 is insoluble in methanol, it was confirmed that polydiacylhydrazine 8 was decomposed into low molecular weight compounds.

Claims (7)

A method for decomposing a polymer compound, the method comprising the step of bringing a nitrogen oxide into contact with a polymer compound having a divalent group represented by the following chemical formula (1).

(In the chemical formula (1) above, the bond with a wavy line represents a bond to another atom.) The method for decomposing a polymer compound according to claim 1, wherein the polymer compound is at least one selected from the group consisting of a cured epoxy resin, a crosslinked vinyl polymer, and a polyurethane. A decomposable adhesive composition comprising a polymer compound having a divalent group represented by the following chemical formula (1), and decomposing upon contact with nitrogen oxides:

(In the above chemical formula (1), the bond with a wavy line represents a bond to another atom.) A method for separating a bonded body bonded with a cured product of the decomposable adhesive composition according to claim 3, comprising contacting the cured product with nitrogen oxide. A degradable paint composition characterized by containing a polymer compound having a divalent group represented by the following chemical formula (1), and decomposed by contacting with nitrogen oxides.

(In the chemical formula (1) above, the bond with a wavy line represents a bond to another atom.) A method for removing a paint film from a painted surface, which comprises bringing nitrogen oxide into contact with a painted surface provided with a paint film formed using the degradable paint composition according to claim 5. By bringing nitrogen oxide into contact with a fiber-reinforced plastic containing a polymer compound having a divalent group represented by the following chemical formula (1) as a matrix, the matrix is decomposed and the fibers contained in the fiber-reinforced plastic are separated. A method for recovering fibers contained in fiber-reinforced plastics.

(In the chemical formula (1) above, the bond with a wavy line represents a bond to another atom.)