KR101978772B1 - Method and composition for depolymerization of cured epoxy resin materials - Google Patents

Abstract

Compounds and reaction solvents represented by the formula XOmYn, where X is hydrogen or an alkali or alkaline earth metal, Y is halogen, m satisfies 1 ≦ m ≦ 8, and n satisfies 1 ≦ n ≦ 6 As a composition comprising, it is possible to depolymerize the cured epoxy resin using a composition in which X is dissociated from XOY and Y radicals may be provided in the reaction solvent. This enables very simple and fast treatment of the depolymerization of the cured epoxy resin at a temperature of 200 ° C. or lower, more preferably 100 ° C. or lower, and can reduce the process cost and required energy. In addition, it is possible to replace the reaction system using the organic solvent as a main solvent, thereby solving the problem of contamination caused by the organic solvent acts as a separate pollution source can minimize the environmental pollution or pollution. Moreover, depolymerization reaction efficiency can be improved, without using the reaction system which uses an organic solvent as a main solvent. Moreover, the epoxy resin hardened | cured material which is comparatively difficult to decompose | disassemble can also be easily decomposed. Moreover, the fall of the characteristic of the filler collect | recovered after decomposition | disassembly of the epoxy resin hardened | cured material can be prevented, and the recycling filler which is excellent in a characteristic can be obtained.

Description

Process and composition for depolymerization of cured epoxy resin

The present specification relates to a method and composition for depolymerizing a cured epoxy resin, and specifically, a method for depolymerizing a cured epoxy resin and a composition used therein, a method for separating a filler from a cured epoxy resin, a filler obtained through the same, and the like. will be.

An epoxy resin is a thermosetting resin which consists of a network polymer formed by ring opening of the epoxy group which arises when the epoxy monomer which has two or more epoxy groups in a molecule is mixed with a hardening | curing agent. Epoxy resins are used as high functional raw materials that are essential in all industries such as adhesives, paints, electronics / electrics, civil engineering / building, etc. due to their excellent chemical resistance, durability and low volume shrinkage during curing.

In the composite material field, which is an important issue in recent years, the epoxy resin is used in various places such as aerospace, information and communication technology, and new energy field in combination with various filler materials, and thus the demand is increasing worldwide. In particular, carbon fiber reinforced plastic (CFRP) made by mixing with carbon fiber is widely used as a core material in the automotive field or aerospace because it exhibits light physical properties and durability. Epoxy resins are also widely used to make higher performance materials by mixing with other polymeric resin materials.

Epoxy resins form a three-dimensional network crosslinked structure after curing, which is very resistant to chemicals. This has the advantage of providing excellent durability and corrosion resistance to the material, but also has the disadvantage of being very difficult to process and recycle the used material.

As a result, most of the cured epoxy resin is currently disposed in a landfill method, which is a large economic waste and may cause serious environmental pollution.

Recently, as the amount of the composite material of the epoxy resin and the filler is gradually increased, researches on the technology of selectively decomposing the epoxy resin in order to effectively separate the relatively expensive filler material compared to the epoxy resin are being actively conducted.

Pyrolysis is currently the most commonly used method for the decomposition of epoxy resins and separation of filler materials. For example, Carbon Fiber Reinforced Plastic (CFRP), which uses carbon fiber as a filler material, is treated and recycled by thermal decomposition of about 1,000 tons per year, led by Japanese companies such as Toray, Teijin, and Mitsubishi. However, in order to separate the carbon fiber through the pyrolysis process, a pretreatment step for mechanically grinding the CFRP is required. In the process of grinding the CFRP up to several mm in size, the carbon fiber may be crushed, and thus the carbon fiber recycled. Due to the shorter the length of the has a problem that adversely affects the properties of the carbon fiber. In addition, the pyrolysis process requires a high temperature of 500 ° C. or more, and at such a high temperature, a problem in which harmful substances such as dioxins are generated due to the combustion of organic compounds also occurs.

Therefore, several chemical decomposition methods have been studied to decompose epoxy resins efficiently at lower temperatures.

For example, when the epoxy resin is decomposed under a supercritical or subcritical fluid, the cured epoxy resin may be efficiently processed at a temperature lower than that of the pyrolysis process at about 250 to 400 ° C. The use of such a method has the advantage that the properties of the recovered filler material are relatively less than that of the pyrolysis method.

However, according to the results of the present inventors, since the method still requires a high temperature and a high pressure of 10 atm or more, there is a constraint that economic efficiency is not high because a special process equipment capable of withstanding such conditions is required.

On the other hand, studies are being conducted to decompose epoxy resins under more general and mild process conditions, but relatively difficult to decompose epoxy resins such as polyfunctional epoxy resins or acid anhydride curing agents or aromatic diamine curing agents. There are disadvantages in that various epoxy resin cured products cannot be dissolved, and the reaction time is long and the reaction energy is high. In addition, there are still problems such as the use of various organic solvents harmful to the human body as the main solvent of the reaction system.

In particular, many prior arts using organic solvents as main solvents for epoxy resin decomposition are known.

For example, it is disclosed to depolymerize a substrate by waste printing by adding an electrolyte containing an alkali metal and adding an organic solvent (Patent Document 2).

Moreover, the technique of processing with an organic solvent and an oxidizing agent in the sealed reaction container after grind | pulverizing and acid-processing an epoxy resin is also disclosed (patent document 3).

In addition, it is disclosed that the epoxy resin is decomposed using hydrogen peroxide and acetone (Non-Patent Document 2).

Moreover, the technique of processing an epoxy resin composite material with the processing liquid containing the alkali metal compound and organic solvent which removed water (patent document 4) is disclosed.

Moreover, it is disclosed that the epoxy resin prepolymer is brought into contact with a non-flotonic organic solvent having a dipole moment of 3.0 or more to dissolve the epoxy resin prepolymer in a solvent (Patent Document 5).

In addition, it discloses using the organic solvent containing furan-2-carbaldehyde as an extraction solvent or a cracking solvent in order to isolate | separate carbon fiber from CFRP (patent document 6).

The techniques describe the ability of an epoxy to decompose with an organic solvent in mild conditions at relatively low temperatures.

However, these techniques are organic solvent reaction systems using the organic solvent itself as the main means for dissolving the epoxy resin, and since the organic solvent itself acts as a contaminant, there is an inherent limitation to solve the contamination problem by the organic solvent. . In addition, there is an applicability problem that is difficult to apply to the epoxy resin, which is difficult to decompose, or a large amount of energy is required for the reaction, which is still unsatisfactory in terms of reaction efficiency.

Korean Patent Application Publication No. 2002-66046 Korean Patent Application Publication No. 2011-0113428 Chinese Patent No. 102391543 Japanese Patent Application Publication No. 2005-255899 Japanese Patent Application Publication No. 2013-107973 United States Patent Application Publication No. 2014-0023581

Mater. Res. Bull. 2004, 39, 1549 Green Chem., 2012, 14, 3260

In exemplary embodiments of the present invention, in one aspect, for example, it is possible to depolymerize the cured epoxy resin very simply and quickly at conditions of 200 ° C. or lower, more preferably 100 ° C. or lower, and reduce process cost and required energy. It is an object of the present invention to provide a depolymerization method of an epoxy resin and a composition used therein, and a depolymerization product obtained using the same.

In an exemplary embodiment of the present invention, in another aspect, it is possible to replace the organic solvent reaction system which is a reaction system containing the organic solvent as the main solvent, thereby solving the problem of contamination due to the organic solvent acts as a separate pollutant The present invention provides a method for depolymerizing an epoxy resin and a composition used therein, and a depolymerization product obtained by using the same.

In another exemplary embodiment of the present invention, in another aspect, a depolymerization method of an epoxy resin capable of increasing the depolymerization reaction efficiency of an epoxy resin cured product without using an organic solvent reaction system which is a reaction system having an organic solvent as a main solvent. And compositions used therein, and depolymerization products obtained using the same.

In another exemplary embodiment of the present invention, in another aspect, a method for depolymerization of an epoxy resin and a composition used therein, and a depolymerization product obtained using the same, which can easily decompose a cured epoxy resin which is relatively difficult to decompose, are provided. I would like to.

In another embodiment of the present invention, in another aspect, a method for recovering the filler from the cured epoxy resin to prevent the degradation of the filler recovered after the decomposition of the cured epoxy resin to obtain a recycled filler having excellent properties To provide a filler obtained through this.

In exemplary embodiments of the present invention, as a depolymerization composition of a cured epoxy resin, the formula XOmYn, wherein X is hydrogen or an alkali metal or an alkaline earth metal, Y is halogen, m satisfies 1 ≦ m ≦ 8, n is satisfying 1 ≦ n ≦ 6) and a reaction solvent, wherein in the reaction solvent, X is dissociated from XOmYn and Y radicals can be provided. To provide.

In exemplary embodiments of the present invention, as the depolymerization method of the cured epoxy resin, it provides a cured epoxy resin cured product, characterized in that the cured epoxy resin cured product using the epoxy resin cured polymer composition.

In exemplary embodiments of the present invention, as the depolymerization product of the cured epoxy resin, the product provides a cured epoxy resin depolymerization product, characterized in that it comprises a CY (Y is halogen) bond Y is bonded to carbon. .

In exemplary embodiments of the present invention, a method of separating a filler from an epoxy resin cured product, the method comprising: depolymerizing an epoxy resin cured product using the epoxy resin cured polymer composition; And obtaining a filler from the cured epoxy resin cured product, and a method of separating the filler from the cured epoxy resin product and a filler separated therefrom.

According to exemplary embodiments of the present invention, depolymerization of the cured epoxy resin can be very simple and fast, for example, at a temperature of 200 ° C. or lower, more preferably 100 ° C. or lower, and a process cost and energy consumption can be reduced. have. In addition, it is possible to replace the reaction system using the organic solvent as a main solvent, thereby solving the problem of contamination caused by the organic solvent acts as a separate pollution source can minimize the environmental pollution or pollution. Moreover, depolymerization reaction efficiency can be improved, without using the reaction system which uses an organic solvent as a main solvent. Moreover, the epoxy resin hardened | cured material which is comparatively difficult to decompose | disassemble can also be easily decomposed. Moreover, the fall of the characteristic of the filler collect | recovered after decomposition | disassembly of the epoxy resin hardened | cured material can be prevented, and the recycling filler which is excellent in a characteristic can be obtained.

1 is a photograph of the CFRP before depolymerization in Example 1 of the present invention and the carbon fibers recovered as a result of Example 1. FIG.
Figure 2 is a photograph of the change in aqueous sodium hypochlorite solution over time in Example 1 of the present invention.
3 is the result of measuring the pH of the sodium hypochlorite aqueous solution which is the reaction system in Example 1 of this invention, and the nitric acid aqueous solution which is the reaction system in Comparative Example 3, respectively.
Figure 4 is a photograph of a change in the nitric acid aqueous solution over time in Comparative Example 3 of the present invention.
5 is a graph comparing the results obtained by measuring the tensile strength of the carbon fibers (raw carbon fibers) used in the CFRP of Example 1 of the present invention and the carbon fibers recovered as a result of Example 1.
6 is a structural analysis (NMR, GC, GCMS, FT-IR) results of the products obtained as a result of Example 1 of the present invention.
7 is an X-ray photoelectron spectroscopic analysis of graphene oxide before and after the depolymerization step in Example 10 of the present invention. Figure 7a is the case of raw material graphene oxide (GO) before the depolymerization process and Figure 7b is the case of graphene oxide (recycled GO) recovered after the depolymerization.
8 is a graph comparing the results obtained by measuring the tensile strength of the glass fibers used in the cured epoxy resin of Example 12 of the present invention and the glass fibers recovered as a result of Example 12.
9 is a graph showing the depolymerization ratio of the cured epoxy resin according to the dielectric constant in each mixed solvent in Experiment 2 of the present invention.
10 is a graph showing the depolymerization result of Example 1 when the radical donating additive was added in Experiment 3 of the present invention.
11 is a graph showing the depolymerization result of Comparative Example 1 when the radical providing additive was added in Experiment 3 of the present invention.

Term Definition

As used herein, the epoxy resin cured product means various composite materials including an epoxy resin or an epoxy resin. In addition, the epoxy resin cured product is defined to include not only the cured epoxy resin but also some cured epoxy resin or an intermediate material (so-called epoxy resin prepolymer or prepreg) generated during the curing reaction.

The composite material may contain various fillers and / or various polymer resins. For reference, the epoxy resin is produced by a curing reaction of an epoxy compound having two or more epoxy groups in a molecule and a curing agent. The epoxy compound and the curing agent are not particularly limited. The epoxy compound may include, for example, a polyfunctional epoxy compound and the like. In addition, the curing agent includes, for example, one having an aromatic group or an aliphatic group, and, for example, at least one selected from the group consisting of amine groups, acid anhydride groups, imidazole groups, and mercaptan groups It may have a thing.

In the present specification, the filler refers to a filler material constituting an epoxy composite material together with an epoxy resin.

In the present specification, the polymer resin refers to a polymer resin constituting an epoxy resin composite material in addition to the epoxy resin.

The reaction solvent is not limited to the specific phase herein. Thus, it may be primarily liquid, but may include a gas phase. In addition, a super critical phase may also be included.

In the present specification, H ₂ O is mainly liquid water, but is not limited to a liquid phase and may include a gas phase, and may also include a supercritical phase.

The aqueous solution herein is in particular liquid unless indicated to be in a gaseous or supercritical state. It is also a solvent alone, unless otherwise indicated that other solvents are mixed.

In the present specification, the organic solvent reaction system means a reaction system using an organic solvent as the main solvent of the decomposition reaction of the cured epoxy resin.

In the present specification, the H ₂ O reaction system means a reaction system using H ₂ O as the main solvent of the decomposition reaction of the cured epoxy resin. This is in contrast to the organic solvent reaction system, using a H ₂ O based reaction solvent in the depolymerization reaction. H ₂ O based reaction solvents may include other solvents in addition to H ₂ O (ie, can be applied as mixed solvents), but even with such mixed solvents the dielectric constant measured at room temperature is at least 65, or preferably at least 70 Or 75 or greater, or 80 or greater. A particularly preferred example is that the H ₂ O based reaction solvent consists of H ₂ O alone (water permittivity is about 80.2).

Depolymerization time in the present specification means the depolymerization reaction time required to depolymerize all the cured epoxy resin provided in the depolymerization reaction . Depolymerization of all here means that the epoxy resin hardened | cured material (solid material) does not exist substantially (epoxy resin residual rate 5% or less). This can be measured, for example, with a thermogravimetric analyzer (TGA).

For reference, the decomposition rate (%) of the epoxy resin in the epoxy resin cured product may be calculated as follows. Namely, decomposition rate (%) = [(epoxy resin content in epoxy resin cured product-epoxy resin residual amount after decomposition) / (epoxy resin content in epoxy resin composite material)] x100. The epoxy resin residual rate is 100% -degradation rate.

The epoxy resin hardened | cured material which is comparatively hard to dissolve in this specification means the epoxy resin hardened | cured material using the epoxy compound and / or hardening | curing agent which are comparatively hard to disintegrate. For example, polycyclic noblock resins are epoxy compounds that are relatively difficult to decompose compared to BPA. Also, for example, an aromatic curing agent and an acid anhydride curing agent are curing agents that are relatively difficult to decompose in contrast to the aliphatic curing agent.

Dielectric constant herein can be measured using a liquid dielectric constant (dielectric constant meter).

In the present specification, the Y (Y = halogen) radical means · Y having unshared hole electrons. For example, it means · F, · Cl, · Br, and · I.

In the present specification, the depolymerization product includes a C-Y (Y is halogen) bond means that Y is bonded to carbon (for example, carbon of a benzene ring) in the structural formula of the newly formed compound after depolymerization of the cured epoxy resin. Wherein Y is the compound XOmYn used in the depolymerization, where X is hydrogen or an alkali metal or an alkaline earth metal, Y is a halogen, m satisfies 1 ≦ m ≦ 8, and n satisfies 1 ≦ n ≦ 6 ) Is Y.

In the present specification, the pretreatment means a treatment for widening the depolymerization reaction area prior to the depolymerization reaction of the cured epoxy resin.

Acidic composition herein means a composition having an acidity capable of performing chemical pretreatment.

As used herein, the radical providing additive means a compound which is added to the radical generating reaction system of XOmYn to provide radicals to promote the radical generating reaction of XomYn.

In the present specification, the radical-containing compound means a compound having a radical and stable form before being added to the reaction system.

In the present specification, a radical generating compound means a compound that generates radicals in a reaction system.

Illustrative Of embodiments  Explanation

Hereinafter, exemplary embodiments of the present invention will be described in detail.

In exemplary embodiments of the present invention, as the epoxy resin cured depolymerization composition, the formula XOmYn, wherein X is hydrogen or an alkali metal or an alkaline earth metal, Y is halogen, m satisfies 1 ≦ m ≦ 8, n is a number satisfying 1 ≦ n ≦ 6), and a cured epoxy resin cured polymer composition wherein X is dissociated from XOmYn and Y radicals are provided in the reaction solvent, and It provides a method for depolymerizing a cured epoxy resin with a composition.

Surprisingly, the inventors have found that the cured epoxy resin can be depolymerized very quickly and simply in a composition in which the specific compound and the reaction solvent (especially the H ₂ O based reaction solvent) are combined, without using an organic solvent based reaction system. Turned out. It is considered that the choice of the reaction solvent and the specific compound used therewith is important in order to polymerize the cured epoxy resin with low energy and to increase the reaction efficiency under low temperature mild conditions. In addition, as will be described in more detail below, in order to enable the depolymerization of the cured epoxy resin of the compound and to increase the depolymerization efficiency, it is considered important to control the dielectric constant of the reaction solvent to a predetermined value or more.

The relevant mechanisms should be further studied, but in the depolymerization according to exemplary embodiments of the present invention X is first dissociated in the reaction solvent (especially H ₂ O based reaction solvent) and finally Y radicals [the non-covalent electrons That is, it is considered that Y is produced, and the Y radical (· Y) is believed to depolymerize the cured epoxy resin while forming CY by bonding to C of the cured epoxy resin. In addition, in order to perform dissociation of X and Y radical generation and depolymerization reaction of the corresponding Y radical to the cured epoxy resin with low energy, the permittivity of the reaction solvent should be adjusted to a predetermined value or more.

Thus, in exemplary embodiments of the present invention, the reaction solvent is selected to dissociate X from the XOmYn to which it is ionic bond, and also it must be able to effectively produce the Y radical after X dissociates. In addition, in order to increase the reaction efficiency, the dielectric constant of the reaction solvent measured at room temperature should be 65 or more, or 70 or more, or 75 or more, or 80 or more.

In an exemplary embodiment, such a reaction solvent is preferably an H ₂ O based reaction solvent. In decomposing the cured epoxy resin using the compound represented by the formula XOmYn, the dielectric constant of the H ₂ O based reaction solvent used together affects the depolymerization reaction efficiency of the epoxy resin polymer. The reason is that unlike the organic solvent in the organic solvent reaction system, the H ₂ O based reaction solvent does not directly decompose the cured epoxy resin, but dissociates X and generates Y radicals from the compound XOmYn which depolymerizes the cured epoxy resin. It is thought that this is because the product is involved in the epoxy resin, and thus is involved in the epoxy resin depolymerization reaction efficiency. The dielectric constant of the H 2 O based reaction solvent measured at room temperature should be at least 65, or at least 70, or at least 75, or at least 80. At dielectric constants above 65, the reaction efficiency begins to increase rapidly. A particularly preferred example is that the H ₂ O based reaction solvent consists of H ₂ O alone (water permittivity is about 80.2). When the H ₂ O based reaction solvent becomes H ₂ O alone, the decomposition efficiency of the cured epoxy resin increases dramatically. (See Experimental Example 2 described later).

In contrast, in the organic solvent-based reaction system of the prior art described above, the cured epoxy resin is directly dissolved using the organic solvent as the main solvent. Even if XOmYn is added to the organic solvent, X cannot be dissociated, and Y radicals cannot be generated and provided to depolymerization of the cured epoxy resin. For example, NMP has a dielectric constant of 32 and XOmYn does not dissolve.

In this regard, the inventors have examined the decomposition efficiency of the cured epoxy resin according to the dielectric constant. As a result, XOmYn with ionic bonds showed a difference in dissociation and reactivity in water and an organic solvent, resulting in a difference in decomposition efficiency of the cured epoxy resin.

The reason for this is the difference in solubility of the XOmYn compound in water and an organic solvent and the difference in radical generation reaction.

First, in the case of a difference in solubility, a difference occurs in the solubility of XOmYn, an ion-bonding material, due to a difference in polarity (ie, dielectric constant) between water and an organic solvent. This is because the dipole-ion of the solvent must be greater than the ion-ion lattice energy of the ion-bonding material to dissociate the ions.

On the other hand, in the case of the radical formation reaction, the reaction formula for XOmYn to generate radicals in water for the first time is as shown in [Scheme 1]. Therefore, the radical generation reaction of XOmYn must be allowed to occur, and also, in order for the radical generation reaction to occur sufficiently, an equivalent amount of water must exist in order for XOmYn to generate radicals effectively.

Scheme 1

Based on the above, it can be seen that it is necessary to use a solvent having a high dielectric constant, preferably H ₂ O based solvent, which can dissociate XOmYn effectively and provide Y radicals effectively. In addition, in the case of using an organic solvent, since contamination due to the organic solvent and recycling of the organic solvent occur, it is preferable to use an H ₂ O-based solvent from an environmental point of view, and in particular, a H ₂ O alone solvent (reaction solvent). Most preferably 100% by weight or 100% by volume of H ₂ O.

Moreover, it is believed that the above-described Y (halogen) radicals generate better radicals because of the low homogeneous dissociation energy required for the production of radicals. For example, the Y (halogen) radical has a low value of homolytic dissociation energy, for example, as compared with the OH radical in the acetone and hydrogen peroxide system of Non-Patent Document 2. This means that in the case of employing the Y (halogen) radical, for example, hydrogen radicals can be effectively formed at a lower energy as compared with materials such as hydrogen peroxide, thereby depolymerizing the cured epoxy resin with less energy. Accordingly, it is possible to depolymerize the cured epoxy resin at a lower temperature and at the same time effectively depolymerize the cured epoxy resin.

As described above, the depolymerization product is replaced by the Y radical by the Y radical generated by the reaction in which XOmYn is dissociated. That is, it has a C-Y bond.

Such a reaction mechanism can be described as, for example, the scheme below.

Scheme 2

As in Scheme 1 above, for example, the depolymerization product may comprise one or more such as Product Example 1, Product Example 2, Product Example 3, and the like. That is, the depolymerization product has a C-Y bond in which some carbon (such as some carbon of the benzene ring) is bonded to Y.

Accordingly, in exemplary embodiments of the present invention, as a depolymerization product of a cured epoxy resin product, a depolymerization product of a cured epoxy resin product comprising a C-Y (Y to halogen) bond in which Y is bonded to carbon of the product. For reference, Experiment 1, which will be described later, shows the results of analyzing three examples of the depolymerization product in which the C-Y bond is formed. The analysis result indicates that the depolymerization product according to the exemplary embodiments of the present invention has the C-Y bond.

When the depolymerization of the cured epoxy resin is carried out using the depolymerized composition of the cured epoxy resin as described above, the cured epoxy resin cured at the end of life is less than, for example, 200 ° C or less, more preferably 100 ° C or less. Very simple and fast with energy. This result is significantly lowered the reaction temperature, unlike the conventional thermal decomposition method (about 200 ~ 400 degrees).

In addition, in the case where the reaction solvent and the compound are differently combined, for example, an organic solvent may be used as in Comparative Example 1 (not dissolved) in which hydrogen peroxide and acetone are mixed, or in Comparative Example 2 (not dissolved) in which sodium hypochlorite is mixed with acetone. It can be seen that the reaction efficiency is remarkably high even when the dielectric constant is low and the comparative example 3 (reaction time 12 hours) using the nitric acid aqueous solution is used. Moreover, unlike conventional techniques using organic solvent based reaction systems, the use of H ₂ O based reaction systems is environmentally advantageous since it may not use organic solvents that are harmful to humans.

Meanwhile, in the exemplary embodiments of the present invention, the filler material contained in the cured epoxy resin may be easily separated and recycled as described above. The filler thus obtained can be prevented from degrading the properties of the filler despite the decomposition process, which is very advantageous for recycling.

In an exemplary embodiment, X in XOmYn is hydrogen or an alkali metal such as lithium, potassium, sodium, or an alkaline earth metal such as calcium, magnesium. In an exemplary embodiment, Y in XOmYn is a halogen element such as F, Cl, Br, I, and the like.

In a non-limiting example, m and n can be natural numbers in the above range. However, it is not limited to natural water and may be a minority, for example, when forming a complex.

In a non-limiting example, for example when m is 1 and n is 1 in XOmYn, for example, HOF, HOCl, HOBr, HOI, NaOF, NaOCl, NaOBr, NaOI, LiOF, LiOCl, LiOBr, LiOI, KOF , KOCl, KOBr, KOI and the like.

In addition, when m is 2 and n is 1, for example, HO ₂ F, HO ₂ Cl, HO ₂ Br, HO ₂ I, NaO ₂ F, NaO ₂ Cl, NaO ₂ Br, NaO ₂ I, LiO ₂ F, LiO ₂ Cl, LiO ₂ Br, LiO ₂ I, KO ₂ F, KO ₂ Cl, KO ₂ Br, KO ₂ I and the like.

In addition, when m and n are each 2, for example, Ca (OF) ₂ , Ca (OCl) ₂ , Ca (OBr) ₂ , Ca (OI) ₂ , and the like.

In addition, when m is 3 and n is 1, for example, HO ₃ F, HO ₃ Cl, HO ₃ Br, HO ₃ I, NaO ₃ F, NaO ₃ Cl, NaO ₃ Br, NaO ₃ I, LiO ₃ F, LiO ₃ Cl, LiO ₃ Br, LiO ₃ I, KO ₃ F, KO ₃ Cl, KO ₃ Br, KO ₃ I and the like.

In addition, when m is 4 and n is 1, for example, HO ₄ F, HO ₄ Cl, HO ₄ Br, HO ₄ I, NaO ₄ F, NaO ₄ Cl, NaO ₄ Br, NaO ₄ I, LiO ₄ F, LiO ₄ Cl, LiO ₄ Br, LiO ₄ I, KO ₄ F, KO ₄ Cl, KO ₄ Br, KO ₄ I and the like.

In the case of m = 6 and n = 2, for example, MgO ₆ F ₂ , MgO ₆ Cl ₂ , MgO ₆ Br ₂ , MgO ₆ I ₂ , CaO ₆ F ₂ , CaO ₆ Cl ₂ , CaO ₆ Br ₂ , CaO ₆ I ₂ , SrO ₆ F ₂ , SrO ₆ Cl ₂ , SrO ₆ Br ₂ , SrO ₆ I ₂ , BaO ₆ F ₂ , BaO ₆ Cl ₂ , BaO ₆ Br ₂ , BaO ₆ I ₂ , and the like.

In the case of m = 1 and n = 3, for example, NaOCl ₃ And may be NaOCl ₄ when m = 1, n = ₄ And the like.

The maximum value of m for forming XOmYn may be 8, such as MgO ₈ Cl ₂ , CaO ₈ Cl ₂ , SrO ₈ Cl ₂ , BaO ₈ Cl ₂ , and the like. In addition, when the maximum value of n for forming XOmYn is 6, for example, NaOCl ₆ may be used.

In an exemplary embodiment, the H ₂ O based solvent is particularly preferably an aqueous solution (H ₂ O alone, water alone in the liquid phase) as described above.

In an exemplary embodiment, when X is an alkali metal or alkaline earth metal in XOmYn, the pH conditions of the depolymerization composition (or aqueous solution) are adjusted to a weakly acidic, neutral, basic pH of 1 or higher. It is thought that the pH conditions must be adjusted in such a manner that X (alkali metal or alkaline earth metal) is more easily decomposed into XOH or X (OH) ₂ in the H ₂ O based reaction system.

In a non-limiting example, the pH of the depolymerization composition (or aqueous solution) is 1-14, and more preferably pH 8-14 in terms of reactivity.

In an exemplary embodiment, the depolymerization reaction temperature is, for example, less than 250 ° C. (eg, 20 ° C. or more but less than 250 ° C.), or 200 ° C. or less (eg, 20-200 ° C.), or 100 ° C. or less (eg, 20-100 ° C. or 20-70). ° C).

In an exemplary embodiment, the H ₂ O based reaction solvent can be liquid, gaseous, and supercritical. Using a liquid phase is a simple process and requires less reaction energy. In the embodiments of the present invention, even when the liquid phase is used, it is possible to depolymerize rapidly at a low temperature, but it is a matter of course that a gas phase and a supercritical state can be used intentionally. In this case, the supercritical state can shorten the reaction time. However, the reaction apparatus and the process are complicated.

In an exemplary embodiment, further comprising a radical providing additive together with XOmYn is preferred in view of further promoting depolymerization reaction of the cured epoxy resin. As defined above, the radical providing additive means a compound which is added to the radical generating reaction system of XOmYn to provide a radical so as to promote the radical generating reaction of XomYn.

Such radical providing additives may be compounds in a stable form (referred to as radical containing compounds) which already have radicals before they are added to the reaction system or compounds which generate radicals in the reaction system. Compounds that generate radicals in the reaction system, referred to as radical generating compounds, may be compounds that generate radicals through chemical reactions or physical actions.

In a non-limiting example, examples of such radical donating additives include BPO (benzoyl peroxide), sodium percarbonate, Fremy salt [disodium nitrosodisulfonate], TEMPO [(2,2,6) , 6-tetramethyl-piperidin-1-yl) oxyl; (2,2,6,6-Tetramethyl-piperidin-1-yl) oxyl].

Fremy salt, TEMPO, etc. are the radical containing compounds which have a radical in itself, BPO, sodium percarbonate, etc. are compounds which generate a radical in a reaction system.

Specifically, the radical production mechanism in the reaction system, for example with sodium percarbonate, can be described, for example, as in the reaction scheme below.

Scheme 3

As in [Scheme 3], sodium percarbonate generates reactive species in the peracid form by water in the reaction system, and the peracid reactive species can exist as carbonate radicals and hydroxyl radicals in the reaction system.

The radicals thus generated promote the radical production reaction from XOmYn. That is, compared to the reaction in which HOmYn (refer to Scheme 1 above, in relation to HOmYn) becomes three radicals as in Scheme 4 below, a stable compound is produced after the reaction due to the presence of radicals before the reaction, thereby producing a reaction. The equilibrium of moves to the right.

Scheme 4

Meanwhile, in the case of BPO, two phenyl radicals are generated by heat (Scheme 5), and in the case of premi salt and TEMPO, the compound itself exists in the form of a radical (Formula 1, Formula 2). Accordingly, as in the case of sodium percarbonate, it is additionally added to the radical generating reaction system of XOmYn to provide radicals to promote the radical generating reaction of XOmYn.

Scheme 5

[Formula 1]

[Formula 2]

As such, the depolymerization reaction of the cured epoxy resin is also promoted by promoting the radical formation reaction of XOmYn. The kinetics of the decomposition reaction of carbon-carbon bonds using radicals is exponentially proportional to the concentration of radicals in the reaction system, as shown in Scheme 6 below. This kinetics also apply to the reactions of the embodiments of the present invention. Therefore, due to the above-described radical providing additive, the radical concentration in the reaction system is increased, thereby increasing the reaction rate to promote the depolymerization reaction of the cured epoxy resin.

Scheme 6

In an exemplary embodiment, the radical providing additive may be included in an amount of 0.00001 to 99 wt%, preferably 0,1 to 10 wt%, based on 100 wt% of the total composition (reaction solvent + XO _m Y _n compound). have.

In an exemplary embodiment, the pretreatment may be further performed to increase the reaction surface area of the cured epoxy resin prior to dissolving the cured epoxy resin into the polymerization reaction. As described above, according to exemplary embodiments of the present invention, although a separate pretreatment is not performed, the reaction time can be significantly reduced at low temperatures, but the reduced reaction time is further reduced through pretreatment which increases the reaction surface area. Can be. That is, through the above-described pretreatment, the reaction area of the cured epoxy resin may be increased to allow subsequent depolymerization reaction to occur more smoothly.

In an exemplary embodiment, the pretreatment may use one or a combination of physical pretreatment and chemical pretreatment.

In a non-limiting example, the physical pretreatment can be for example grinding. The grinding method may be one or two or more selected from dry grinding method and wet grinding method, and may include hammer mill, cutter mill, flake crusher, feather mill, pin mill, impact mill, fine mill, jet mill, micron mill, ball mill, Grinding may be performed using one or more selected from the group consisting of oil mills, hydro mills, aqua risers. In an exemplary embodiment, the pulverized epoxy resin cured product may have a size of about 1 μm to about 10 cm.

In a non-limiting example, the chemical pretreatment may be to impregnate an acidic composition with an epoxy resin cured product (ie, acid treatment).

In a non-limiting example, the acidic composition used in the impregnation method may have a pH of 5.0 or less, a temperature of 20-250 ° C., from after impregnating the epoxy resin cured product to the epoxy resin to separate the cured epoxy resin. The time may be 0.1 to 24 hours. Then, the separated epoxy resin cured product is washed.

In a non-limiting example, the acidic composition may be, for example, a gaseous composition consisting of one or more materials selected from the group consisting of air, nitrogen, argon, helium, water vapor. In addition, the acidic composition is water, acetone, acetic acid, ethyl acetate, methyl ethyl ketone, N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone), N, N- dimethylformamide (N, N- dimethylformamide), N, N-dimethylacetamide, tetrahydrofuran, acetonitrile, t-butanol, n-butanol, n N-propanol, i-propanol, ethanol, methanol, ethylene glycol, dimethyl sulfoxide, 1,4-dioxane It may be a liquid composition consisting of one or more selected from the group consisting of. Moreover, the said gaseous or liquid composition can be used individually or in combination. However, the use of an organic solvent in the acidic composition is not preferable from an environmental point of view.

In an exemplary embodiment, the epoxy resin cured product to be degraded may include various fillers and / or polymer resins.

In an exemplary embodiment, the filler is carbon fiber or other graphite, graphene, graphene oxide, reduced graphene, carbon nanotubes, glass fibers, inorganic salts, metal particles, ceramic materials, monomolecular organic compounds, monomolecular silicon compounds It may be one or more selected from silicone resins.

In an exemplary embodiment, the polymer resin is an acrylic resin, an olefin resin, a phenol resin, a natural rubber, a synthetic rubber, an aramid resin, a polycarbonate, a polyethylene terephthalate, a polyurethane, a polyamide, a polyvinyl chloride, a polyester, a polystyrene, a poly It may be any one or two or more selected from acetal, acrylonitrile butadiene styrene, styrene acrylonitrile.

In an exemplary embodiment, the XOmYn compound may be 0.001 to 99 wt% based on 100 weight of the total composition (reaction solvent + XOmYn compound). In a non-limiting example, when the reaction solvent is, for example, an aqueous solution, the XOmYn compound may be included in an amount of 0.001 to 99% by weight based on the entire aqueous solution including the XOmYn compound.

In an exemplary embodiment, the cured epoxy resin may be 1 to 90 parts by weight based on 100 parts by weight of the depolymerization composition (reaction solvent + XOmYn compound). In a non-limiting example, when the reaction solvent is an aqueous solution, the cured epoxy resin (eg, CFRP) may be 1 to 90 parts by weight based on 100 parts by weight of an aqueous solution including an XOmYn compound.

In an exemplary embodiment, the method may further include preparing the XOmYn compound. XomYn thus prepared is provided to the epoxy resin cured product to perform chemical depolymerization.

In a non-limiting example, for example, when the XOmYn compound is HOY, for example, the depolymerization composition is added to the cured epoxy resin by bubbling a halogen (eg Cl) gas into water to form an aqueous solution of HOY and adding a cured epoxy resin thereto. Can provide.

That is, in a non-limiting example, when the compound is, for example, HOCl, depolymerization may be performed by bubbling Cl ₂ gas into water to make an aqueous HOCl solution, and then adding a cured epoxy resin such as CFRP.

Alternatively, in a non-limiting example, the XomYn compound is XOY (where X is an alkali metal and Y is halogen) and XY is electrolyzed in water to form an aqueous solution comprising the XOY compound, wherein the cured epoxy resin is added thereto. The depolymerization composition can be provided to the epoxy resin cured product by putting.

That is, in a non-limiting example, when the compound is NaOCl, NaCl may be electrolyzed in water to make an aqueous solution including NaOCl, and then a depolymerization may be performed by adding a cured epoxy resin such as CFRP thereto.

On the other hand, in a non-limiting example, the XomYn compound may be prepared through a chemical or physical reaction in the depolymerization reactor (depolymerization reaction system) of the cured epoxy resin.

For example, in a non-limiting example, an aqueous sodium hypochlorite (NaOCl) solution can be produced by mixing sodium hydroxide (NaOH) solution with chlorine (Cl ₂ ) in a depolymerization reactor, which can be used to depolymerize the cured epoxy resin.

Meanwhile, exemplary embodiments of the present invention include the steps of depolymerizing a cured epoxy resin with a depolymerization composition comprising a XOmYn compound and a reaction solvent as described above; And obtaining a filler from the depolymerized cured epoxy resin through, for example, filtration or extraction, and a method for separating the filler from the cured epoxy resin, and the filler thus obtained.

The filler separated and recovered from the epoxy resin cured product can prevent the deterioration of properties as compared with before the depolymerization step of the epoxy resin cured product, whereby a recycled filler having excellent properties can be obtained.

For example, as can be seen from the examples described below, when the filler is carbon fiber, the degradation of properties such as tensile strength and elongation of the raw material filler carbon fiber contained in the cured epoxy resin may be very small, for example, about 13% or less. . In connection with this, in the case of the carbon fiber recovered from CFRP using the pyrolysis method, the tensile strength decreases by about 15% or more relative to the raw material carbon fiber (Non-Patent Document 1). In contrast, when depolymerized according to embodiments of the present invention, the carbon fiber can be recovered with little deterioration in the tensile strength property of the carbon fiber.

In an exemplary embodiment, the method may repeat the decomposition process by adding fresh epoxy resin cured product to the remaining reaction solvent after depolymerizing the cured epoxy resin.

The product obtained by superposing | polymerizing by hardening an epoxy resin hardened | cured material by the above method is a low viscosity aqueous solution state, and there is no insoluble suspended matter on a gel, and a filler can be isolate | separated from this aqueous solution through filtration or extraction, for example.

Hereinafter, specific embodiments according to exemplary embodiments of the present invention will be described in more detail. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and the following examples are only common in the art while making the disclosure of the present invention complete. It is to be understood that the invention is intended to facilitate the practice of the invention.

[Experiment 1]

In the following examples, water alone was used as the reaction solvent. Aqueous solution (liquid phase) was used in the other examples except for the aqueous solution in gas phase, Example 4, and the aqueous solution in the supercritical state. The dielectric constant of water is 80.2.

In Comparative Examples 1 and 2, a mixed solvent of water and acetone was used, and the dielectric constant was about 44.

On the other hand, Example 5 is to increase the amount of waste CFRP to 16 times compared to Example 1, Examples 6 to 9 to increase the amount of waste CFRP to 10 times compared to Example 1, but the amount of aqueous sodium hypochlorite solution Increased.

In addition, Example 7 performed depolymerization after pulverization of waste CFRP, Example 8 depolymerized after waste acetic acid impregnation, and Example 9 depolymerized waste CFRP after pulverization and impregnation.

[ Example  One: Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Disintegration of Cured Epoxy Resin and Separation of Filler (Carbon Fiber)]

The epoxy resin cured material used in the present Example 1 is waste CFRP. The waste CFRP consists of an epoxy resin cured product and carbon fiber produced using an epoxy compound in the form of diglycidyl ether of bisphenol A containing a halogen element and an aromatic curing agent containing an aromatic amine group. This CFRP is known to be generally difficult to decompose because it uses an aromatic curing agent.

0.1 g of the waste CFRP was added to 70 mL of an aqueous 2 mol / L sodium hypochlorite solution contained in an open glass container, followed by stirring at 70 ° C. No autoclave was used.

FIG. 1 is a photograph of CFRP before depolymerization used in Example 1 of the present invention and carbon fibers recovered as a result of Example 1. FIG. 2 is a photograph of changes in an aqueous sodium hypochlorite solution containing CFRP over time. The photograph shows the result of measuring the pH of the sodium hypochlorite aqueous solution containing CFRP in FIG. 3.

In addition, in Table 1, when the decomposition of the epoxy resin was completed, the viscosity of the aqueous sodium hypochlorite solution obtained after filtering the carbon fiber was measured using a Brookfield viscometer and the results of measuring the pH are shown in Table 2, before and after the decomposition process. The tensile strength and electrical conductivity change of the carbon fiber of is shown in Table 3. In addition, the details of the electrical conductivity change are shown in Table 4.

After 6 hours, after confirming that the epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the carbon fibers in the aqueous solution were filtered and separated and dried.

In addition, an analysis such as NMR was performed to confirm that the Y-radical (Cl radical in Example 1) is substituted for the depolymerization product of Example 1 to form a C-Y bond.

6 is a structural analysis (NMR, GC, GCMS, FT-IR analysis) of the various products obtained as a result of Example 1 of the present invention. 6A shows product example 1, FIG. 6B shows product example 2, and FIG. 6C relates to product example 3.

Specifically, the solid mixture obtained by filtering the carbon fiber in Example 1 and extracting the product in the form of the aqueous solution remaining with dichloromethane and dried.

For NMR analysis, Agilent Technology's 600 MHz NMR Spectrometer instrument was used, and hydrogen nuclides were measured using deuterium-substituted chloroform as a solvent.

For GC analysis, a GC-2010 Plus instrument from Shimadzu was used, and gas chromatography of the mixture was measured using dichloromethane as a solvent.

For GC-MS analysis, Shimadzu's GCMS-QP2010 instrument was used, and based on the GC results analyzed earlier, a compound having a molecular weight between 30 and 350 was detected.

For FT-IR analysis, ThermoScientific's Nicolet iS 10 instrument was used, and pellets were prepared using a solid mixture and potassium bromide, and then the 500 cm ⁻¹ to 4000 cm ⁻¹ wave lengths were measured.

As can be seen from FIG. 6, the presence of three kinds of compounds having C-Y bonds in common from the NMR, GC-MS, and IR results was confirmed. Therefore, it was found that the compound having the C-Y bond was included in the solid mixture (ie, the depolymerization product of the cured epoxy resin).

[ Example  2: Hypochlorous acid Using (HOCl) aqueous solution Filler (graphene)  Decomposition of Cured Epoxy Resin Containing and Separation of Filler (Graphene)]

The cured product used in Example 2 consisted of epoxy resin and graphene produced using a curing agent containing an aromatic amine group and an epoxy compound in the form of glycidyl ether of cresol novolac. This CFRP is also known to be quite difficult to decompose, since it uses a noblock epoxy compound and an aromatic curing agent.

0.1 g of the cured epoxy resin was added to 70 mL of an aqueous 2 mol / L hypochlorous acid solution in an open glass container, followed by stirring at 70 ° C. No autoclave was used.

After 5.5 hours, after confirming that the epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the graphene in the aqueous solution was filtered and separated and dried.

Table 1 shows the time when the decomposition of the epoxy resin was completed, and the results of measuring the thermal conductivity of the graphene used in the cured epoxy resin of Example 2 of the present invention and the graphene recovered as a result of Example 2 are shown in Table 3. .

[ Example  3: gaseous Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Disintegration of Cured Epoxy Resin and Separation of Filler (Carbon Fiber)]

0.1 g of the same CFRP as used in Example 1 was placed on a wire mesh on top of a pressurized vessel containing 70 mL of 2 mol / L sodium hypochlorite solution, and then the liquid inlet and CFRP inlet of the pressurized vessel were sealed and heated to 120 ° C. It was. A gaseous sodium hypochlorite aqueous solution was thus provided to the CFRP.

The time at which the CFRP decomposition was completed is shown in Table 1.

After 8 hours, after confirming that CFRP was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), water was added from the upper part of the pressure vessel to decompose the epoxy resin on the wire mesh. The resulting product was dissolved and moved to the bottom of the pressure vessel, and the carbon fibers left on the wire mesh were separated and dried.

[ Example  4: Supercritical  State Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Disintegration of Cured Epoxy Resin and Separation of Filler (Carbon Fiber)]

0.1 g of the same CFRP as used in Example 1 was added to 70 mL of an aqueous 2 mol / L sodium hypochlorite solution in a batch reactor with a pressure gauge, and then the reactor was sealed and heated to 374 ° C. using an electric heating jacket. . At this time, the pressure displayed on the pressure gauge was 221 bar.

After 1 hour, the reactor was cooled to room temperature, and then it was confirmed whether CFRP inside the reactor was decomposed.

Increasing the reaction time in units of 1 hour, the decomposition time of the epoxy resin is shown in Table 1.

After 2 hours, it was confirmed that the epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), and the carbon fibers in the reactor were separated and dried.

[ Example  5: Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Epoxy resin Cured product  Decomposition and Of filler (carbon fiber)  detach : CFRP  Increase in volume]

On the other hand, this time the other conditions in the present Example 1 were the same (ie, added to 70 mL of 2 mol / L sodium hypochlorite aqueous solution, and stirred at 70 ℃) to increase the amount of waste CFRP to 16 times (ie , 1.6g). After 12 hours, the decomposition of the epoxy resin was visually confirmed, and the carbon fibers in the aqueous solution were filtered and separated and dried. Table 1 shows the time when depolymerization is completed.

[ Example  6: Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Decomposition of Cured Epoxy Resin and Separation of Filler (Carbon Fiber): Increased CFRP Content]

This time, 1.0 g of the waste CFRP used in Example 1 (increased 10 times compared with Example 1) was added to 100 mL of an aqueous solution of 4 mol / L sodium hypochlorite contained in an open glass container, followed by stirring at 90 ° C. No autoclave was used.

After 8 hours, it was confirmed that CFRP was completely depolymerized (there was no epoxy resin residue through measurement of thermogravimetric analyzer (TGA) after depolymerization), and the carbon fibers in the aqueous solution were separated and dried.

Table 1 shows the time when depolymerization is completed. In addition, the tensile strength and electrical conductivity measurement results of the carbon fiber recovered in Example 6 are also shown in Table 3.

[ Example  7: Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Decomposition of Cured Epoxy Resin and Separation of Filler (Carbon Fiber): Depolymerization after Crushing CFRP]

The other conditions in Example 6 were the same, but 1.0 kg of waste CFRP was ground into fragments having an average diameter of 2.0 mm using a Barley Grinder Crusher manual grinder manufactured by Wellbom, China.

1.0 g of the pulverized epoxy resin cured fragment was added to 100 mL of an aqueous solution of 4 mol / L sodium hypochlorite contained in an open glass container, followed by stirring at 90 ° C. No autoclave was used.

After 4 hours, it was confirmed that CFRP was completely depolymerized (there was no epoxy resin residue through measurement of thermogravimetric analyzer (TGA) after depolymerization), and the carbon fibers in the aqueous solution were separated and dried. Table 1 shows the time when depolymerization is completed.

[ Example  8: Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Decomposition of Cured Epoxy Resin and Separation of Filler (Carbon Fiber): Depolymerization after CFRP Impregnation]

The other conditions in Example 6 were the same, but 1.0 g of waste CFRP was added to 100 mL of 99% acetic acid and heated at 120 ° C. for 30 minutes. The cured epoxy resin was separated and washed with 20 mL of acetone.

The washed epoxy resin cured product was added to 100 mL of an aqueous solution of 4 mol / L sodium hypochlorite contained in an open glass container, followed by stirring at 90 ° C. No autoclave was used.

After 5 hours, after confirming that the cured epoxy resin was completely polymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the carbon fibers in the aqueous solution were separated and dried.

Table 1 shows the time when the depolymerization of the cured epoxy resin was completed. In addition, the tensile strength and electrical conductivity measurement results of the carbon fiber used in Example 8 of the present invention are shown in Table 3.

[ Example  9: Sodium hypochlorite ( NaOCl ) With aqueous solution CFRP  Decomposition of Cured Epoxy Resin and Separation of Filler (Carbon Fiber): Depolymerization after Crushing CFRP and Impregnation]

In Example 6, the other conditions were the same, but 1.0 kg of waste CFRP was pulverized into 1.0 kg of an epoxy resin cured product into fragments having an average diameter of 2.0 mm using a Micro Hammer Cutter Mill automatic grinder manufactured by Glen Creston, UK.

1.0 g of the pulverized epoxy resin cured product was added to 100 mL of 99% acetic acid, heated at 120 ° C. for 30 minutes, filtered through a cellulose filter paper of Advantec, and the cured epoxy resin was separated, and washed with 20 mL of acetone.

1.0 g of the washed epoxy resin cured fragment was added to 100 mL of an aqueous solution of 4 mol / L sodium hypochlorite contained in an open glass container, followed by stirring at 90 ° C. No autoclave was used.

After 3 hours, it was confirmed that CFRP was completely depolymerized (there was no epoxy resin residue through measurement of thermogravimetric analyzer (TGA) after depolymerization), and the carbon fibers in the aqueous solution were separated and dried. Table 1 shows the time when the depolymerization of the cured epoxy resin was completed.

[ Example  10: Iodine acid ( HIO ₃ ) With aqueous solution Filler (graphene oxide)  Decomposition of Cured Epoxy Resin Containing and Separation of Filler (Graphene Oxide)]

The cured product used in Example 10 was composed of the epoxy resin cured product and graphene oxide produced using a curing agent including an epoxy compound in the glycidyl amine form and an acid anhydride group.

0.1 g of the cured product including the epoxy resin was added to 70 mL of a 2 mol / L aqueous solution of iodine acid contained in an open glass container, followed by stirring at 70 ° C. No autoclave was used.

After 5 hours, after confirming that the cured epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the graphene oxide in the aqueous solution was filtered and separated and dried. . Table 1 shows the depolymerization time.

7 is an X-ray photoelectron spectroscopic analysis result of graphene oxide before and after the depolymerization step in Example 10 of the present invention. Figure 7a is the case of raw material graphene oxide (GO) before the depolymerization process and Figure 7b is the case of recovered graphene oxide (recycled GO). In addition, the contents of the respective bonds and the carbon and oxygen elements derived from the X-ray photoelectron spectroscopic analysis are shown in Table 5. It can be seen from the results that there is little change in the properties of graphene oxide before and after the decomposition process.

[ Example  11: perchloric acid ( HClO ₄ ) With aqueous solution Filler (carbon nanotube)  Decomposition of Cured Epoxy Resin Containing and Separation of Filler (Carbon Nanotube)]

The cured product used in Example 11 is a epoxy resin cured product and carbon nanotubes produced using a curing agent containing an aromatic amine group and an epoxy compound in the form of glycidyl ether of cresol novolac as used in Example 2 Was done.

0.1 g of the cured product including the epoxy resin was added to 70 mL of a 2 mol / L aqueous perchloric acid solution contained in an open glass container, followed by stirring at 70 ° C. No autoclave was used.

After 3.5 hours, after confirming that the cured epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the carbon nanotubes in the aqueous solution were separated by filtration and dried. .

Table 1 shows the time when the decomposition of the epoxy resin was completed, and the thermal conductivity of the carbon nanotubes used in the cured epoxy resin of Example 11 of the present invention and the carbon nanotubes recovered as a result of Example 11 were measured. Shown in

[ Example  12: Bromic acid ( HBrO ₃ ) With aqueous solution Filler (glass fiber)  Decomposition of Cured Epoxy Resin Containing and Separation of Filler (Glass Fiber)]

The cured product used in Example 12 was composed of an epoxy resin cured product and a glass fiber produced using a curing agent containing an aromatic amine group and an epoxy compound in the form of glycidyl ether of cresol novolac, as used in Example 2. Was done.

0.1 g of the cured product including the epoxy resin was added to 70 mL of a 2 mol / L bromic acid aqueous solution contained in an open glass container, followed by stirring at 70 ° C. No autoclave was used.

After 4.5 hours, after confirming that the cured epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the glass fiber in the aqueous solution was filtered and separated and dried. Table 1 shows the depolymerization time.

8 is a graph comparing the results obtained by measuring the tensile strength of the glass fibers used in the cured epoxy resin of Example 12 of the present invention and the glass fibers recovered as a result of Example 12. In addition, the tensile strength change of the glass fiber before and after the decomposition process derived from the tensile strength measurement results are shown in Table 3. It can be seen from the results that the characteristic change is small.

[ Example  13: Chlorite ( HClO ₂ ) With aqueous solution Filler (alumina)  Decomposition of Cured Epoxy Resin Containing and Separation of Filler (Alumina)]

The cured product used in Example 13 consists of an epoxy resin cured product and an alumina produced using a curing agent containing an aromatic amine group and an epoxy compound in the form of glycidyl ether of cresol novolac as used in Example 2. lost.

0.1 g of the cured product including the epoxy resin was added to 70 mL of an aqueous 2 mol / L chlorite solution contained in an open glass container, followed by stirring at 70 ° C. No autoclave was used.

After 5 hours, it was confirmed that the epoxy resin cured product was completely depolymerized (there was no residue of epoxy resin through measurement of thermogravimetric analyzer (TGA) after depolymerization), and the alumina in the aqueous solution was filtered and separated and dried.

The completion time of decomposition of the epoxy resin is shown in Table 1, and the results of measuring the thermal conductivity of the alumina used in the cured epoxy resin of Example 13 of the present invention and the resultant alumina are shown in Table 3.

[ Example  14: chloric acid ( HClO ₃ ) With aqueous solution Filler (silicon carbide)  Decomposition of Cured Epoxy Resin Containing and Separation of Filler (Silicon Carbide)]

The cured product used in Example 14 was formed into an epoxy resin cured product and a silicon carbide produced using a curing agent containing an aromatic amine group and an epoxy compound in the form of glycidyl ether of cresol novolac as used in Example 2. Was done.

0.1 g of the cured product including the epoxy resin was added to 70 mL of a 2 mol / L aqueous hydrochloric acid solution contained in an open glass container, followed by stirring at 70 ° C. No autoclave was used. On the other hand, in order to provide an aqueous solution of chloric acid to the epoxy resin cured product, a method of bubbling chlorine gas in water and dipping the cured epoxy resin therein may be performed.

After 4 hours, after confirming that the cured epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the silicon carbide in the aqueous solution was separated by filtration and dried.

Table 1 shows the time when the decomposition of the epoxy resin was completed, and the results of measuring the thermal conductivity of the silicon carbide used in the cured epoxy resin of Example 14 of the present invention and the silicon carbide recovered as a result of Example 14 are shown in Table 3. It was.

[ Example  15: sodium chlorate ( NaClO ₃ ) With aqueous solution Filler (mono molecule organic compounding Separation of Cured Epoxy Resin Containing Water and Separation of Filler (Organic Chemical)]

As used in Example 2, the cured product used in Example 2 was an epoxy resin cured product and a monomolecular organic compound produced using a curing agent containing an aromatic amine group and an epoxy compound in the form of glycidyl ether of cresol novolac. It consisted of the compound BAF EFKA 5207.

0.1 g of the cured product including the epoxy resin was added to 70 mL of a 2 mol / L sodium chlorate aqueous solution contained in an open glass container, followed by stirring at 70 ° C. No autoclave was used.

After 4.5 hours, after confirming that the cured epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), EFKA 5207 in aqueous solution was prepared by Agilent's 1200 series high performance liquid chromatography. After separation was used to dry. Table 1 shows the time when the decomposition of the epoxy resin was completed.

[ Example  16: aqueous sodium hydroxide (NaOH) solution and chlorine ( Cl ₂ Through a mixture of Sodium hypochlorite  ( NaOCl ) Generation of aqueous solution, CFRP  Epoxy resin Cured product  Decomposition and Of filler (carbon fiber)  detach]

0.1 g of waste CFRP as used in Example 1 was added to 70 mL of a 2 mol / L aqueous sodium hydroxide solution contained in a pressurized vessel, and then the chlorine was not allowed to fall below 3 atm through the separate inlet. It stirred at 70 degreeC, putting gas.

After 8 hours, after confirming that the epoxy resin was completely depolymerized (by measuring the thermogravimetric analyzer (TGA) after depolymerization, it was confirmed that there was no epoxy resin residue), the carbon fiber in the aqueous solution was filtered and separated and dried. Table 1 shows the time when the decomposition of the epoxy resin was completed.

[ Comparative example  1: a mixture of hydrogen peroxide and acetone ( H ₂ O ₂  Decomposition of Epoxy Resins in CFRP and Separation of Carbon Fibers]

0.1 g of the same CFRP as used in Example 1 is placed in an open glass container with 2 mol / L hydrogen peroxide and 33% (volume in total solvent) acetone 11 mL (ie 33% by volume of acetone in total solvent, The water volume ratio was added to 67%) and stirred at 70 ° C.

Table 1 shows the decomposition of the epoxy resin. In Comparative Example 1, the epoxy resin did not melt, and carbon fibers could not be separated.

Here, OH radicals were used for epoxy decomposition and the solution had a dielectric constant of about 44. It is considered that the result is insoluble in the present comparative example because the dielectric constant is low, the generation of radicals is difficult, and the amount of OH radicals is low. Note that although the same CFRP as the examples was used (the curing agent of the epoxy resin cured material was considerably difficult to decompose into the aromatic diamine system), the results did not dissolve at all unlike the examples.

[ Comparative example  2: Sodium hypochlorite ( NaOCl ) Decomposition of Epoxy Resin and Isolation of Carbon Fiber Using Mixed Solution of Aqueous Solution and Acetone]

0.1 g of the same CFRP as used in Example 1 was mixed in an open glass container with a 2 mol / L aqueous sodium hypochlorite solution and 33% (volume in total solvent) acetone (i.e. 33% by volume of acetone in total solvent, The water volume ratio was added to 67%), followed by stirring at 70 ° C.

Table 1 shows the decomposition of the epoxy resin. Also in Comparative Example 2, the epoxy resin was not dissolved and the carbon fibers could not be separated. The dielectric constant of the solution used also in this comparative example is about 44. It is thought that the result is insoluble in this comparative example because the dielectric constant is low and cannot generate radicals effectively. Note that although the same CFRP as the examples was used (the curing agent of the epoxy resin cured material was considerably difficult to decompose into the aromatic diamine system), the results did not dissolve at all unlike the examples.

[ Comparative example  3: Decomposition of Epoxy Resin and Separation of Carbon Fiber Using Aqueous Nitric Acid]

0.1 g of the same CFRP as used in Example 1 was added to an aqueous solution of 2 mol / L nitric acid contained in an open glass container, followed by stirring at 70 ° C.

Figure 4 is a photograph of the change of nitric acid solution containing CFRP over time, Figure 3 shows the results of measuring the pH of the nitric acid solution containing CFRP. Also, Table 1 shows the time when the decomposition of the epoxy resin was completed, and Table 2 shows the results of measuring the viscosity of the aqueous nitric acid solution obtained by filtering carbon fibers using a Brookfield viscometer and the results of measuring pH.

After 12 hours, it was confirmed that the epoxy resin cured product was completely depolymerized (there was no epoxy resin residue through measurement of thermogravimetric analyzer (TGA) after depolymerization), and the carbon fiber in the aqueous solution was filtered and separated and dried.

[ Example  And Comparative Examples  Epoxy Degradation Test Results and Recovered Of filler  Characterization]

Table 1 shows the time required for decomposition of the epoxy resin in Examples and Comparative Examples. In addition, the results of measuring the pH and viscosity of the sodium hypochlorite aqueous solution and the nitric acid aqueous solution obtained after filtering the carbon fiber in Example 1 and Comparative Example 3 are shown in Table 2.

Table 3 shows the characteristics of the thermal conductivity, tensile strength, and electrical conductivity before and after depolymerization of the filler of the embodiments. Table 4 shows the electrical conductivity results of Example 1 in more detail. Table 5 shows the contents of the respective bonds and carbon and oxygen elements derived from the X-ray photoelectron spectroscopy analysis in Example 10.

division XOmYn
compound Reaction solvent / dielectric constant Depolymerization Completion Time [h] Example 1 NaOCl Aqueous solution (water only)
Permittivity 80.2 6 Example 2 HOCl Aqueous solution (water only)
Permittivity 80.2 5.5 Example 3 NaOCl Gaseous aqueous solution
(Water alone)
Permittivity 80.2 8 Example 4 NaOCl Supercritical state
Aqueous solution (water only)
Permittivity 80.2 2 Example 5
(CFRP amount
16x increase) NaOCl Aqueous solution (water only)
Permittivity 80.2 12 Example 6
(CFRP amount
10-fold increase / amount of composition) NaOCl Aqueous solution (water only)
Permittivity 80.2 8 Example 7
(CFRP amount
10-fold increase / amount of composition)
(Depolymerization after crushing) NaOCl Aqueous solution (water only)
Permittivity 80.2 4 Example 8
(CFRP amount
10-fold increase / amount of composition)
(Depolymerization after impregnation) NaOCl Aqueous solution (water only)
Permittivity 80.2 5 Example 9
(CFRP amount
10-fold increase / amount of composition)
(Depolymerization after grinding and impregnation) NaOCl Aqueous solution (water only)
Permittivity 80.2 3 Example 10 HIO ₃ Aqueous solution (water only)
Permittivity 80.2 5 Example 11 HClO ₄ Aqueous solution (water only)
Permittivity 80.2 3.5 Example 12 HBrO ₃ Aqueous solution (water only)
Permittivity 80.2 4.5 Example 13 HClO ₂ Aqueous solution (water only)
Permittivity 80.2 5 Example 14 HClO ₃ Aqueous solution (water only)
Permittivity 80.2 4 Example 15 NaClO ₃ Aqueous solution (water only)
Permittivity 80.2 4.5 Example 16 NaOH + Cl ₂
(NaOCl generation) Aqueous solution (water only)
Permittivity 80.2 8 Comparative Example 1 -
(Using hydrogen peroxide) Water + acetone
Dielectric constant of about 44 Insoluble Comparative Example 2 NaOCl Water + acetone
Dielectric constant of about 44 Insoluble Comparative Example 3 -
(Using nitric acid) Aqueous solution
(Water alone)
Permittivity 80.2 12

division Sodium hypochlorite aqueous solution
(Example 1) Nitric acid solution
(Comparative Example 3) pH 9 <1 Viscosity [cP] 10 30000

division
(filler) Before / after depolymerization
Thermal conductivity
[W / mK, 25 ℃] Before / after depolymerization
Tensile Strength [GPa] Before / after depolymerization
Conductivity [S / cm] Example 1
(Carbon fiber) - 4.0 (Before)
3.7 (after) 504.5 (Before)
657.5 (After) Example 2
(Graphene) 4540 (Before)
4041 (after) - - Example 6
(Carbon fiber) - 4.0 (Before)
3.7 (after) 504.5 (Before)
627.5 (after) Example 8
(Carbon fiber) - 4.0 (Before)
3.8 (after) 504.5 (Before)
628.7 (after) Example 11
(Carbon nanotube) 3111 (former)
2769 (after) - - Example 12
(glass fiber) - 3.2 (Before)
2.9 (after) - Example 13
(Alumina) 31.2 (Before)
28.4 (after) - - Example 14 (Silicon Carbide) 167 (Before)
157 (after) - -

division Carbon fiber before use
(Example 1) Recovered carbon fiber
(Example 1) Voltage [V] 4.15 4.19 Current [mA] 1.0 1.0 Resistance [kΩ] 4.15 4.19 Length [cm] 1.0 1.0 Thickness [m] 7.8 6.8 Surface area [m ² ] 47.8 36.3 Conductivity [S / cm] 504.5 657.5 Average conductivity 504.5 S / cm 657.5 S / cm

division Graphene oxide before use
(Example 10) Recovered Graphene Oxide
(Example 10) C-C content 39.7% 40.5% C-OH content 3.6% 3.7% C-O-C content 41.3% 40.2% C = O content 12.5% 13.7% C (= O) -O Content 2.9% 1.9% Carbon element content 66.5% 65.7% Oxygen element content 33.5% 34.3%

As can be seen in the Examples and Comparative Examples of Table 1, the reaction time was relatively very fast despite the low reaction temperature. On the other hand, particularly in Comparative Examples 1 and 2 when acetone was included in the reaction solvent of about 33% by volume (dielectric constant is about 44) it was confirmed that the decomposition of the cured epoxy resin does not proceed.

On the other hand, in the case of Comparative Example 3, an aqueous solution of nitric acid was used, compared with Example 1 using an aqueous sodium hypochlorite solution, the reaction time was very slow twice. In addition, as can be seen in Table 2, the composition used in Example 1 shows a higher pH value than the aqueous solution of nitric acid, and the resulting mixture after decomposing the cured epoxy resin also shows a higher viscosity than when using nitric acid to form a gel phase Not shown. This relatively low viscosity can make the process much easier.

5 is a graph comparing the results obtained by measuring the tensile strength of the carbon fibers (raw carbon fibers) used in the CFRP of Example 1 of the present invention and the carbon fibers recovered as a result of Example 1.

From the tensile strength measurement results of the carbon fibers recovered from Example 1, it was found that by decomposing CFRP using the method of the embodiments of the present invention, carbon fibers having a small decrease in tensile strength (within about 13%) can be recovered from CFRP. Confirmed. The carbon fiber recovered from CFRP using the pyrolysis method shows a deterioration in tensile strength of 15% or more relative to the raw material (Non Patent Literature 1). Indicates that it can be recovered.

In addition, as shown in Table 3, it was confirmed from the results of the filler properties before and after depolymerization that the fillers having a small change in properties can be recovered from the cured epoxy resin by decomposing the cured epoxy resin using the method of the embodiments of the present invention. .

On the other hand, Examples 7 to 9 and Example 6 in Table 1, respectively, using the same epoxy resin cured product and depolymerization composition, Examples 7 to 9 were carried out including the pre-treatment process and Example 6 is a pre-treatment process Proceed without including. Although the depolymerization proceeded rapidly in the case of Example 6, the depolymerization of the cured epoxy resin was carried out in a faster time by including the pretreatment process, and the depolymerization of the cured epoxy resin in the fastest time in Example 9 including both the grinding and impregnation process. This is done.

The shortening time of the completion time of the depolymerization seems to be because the depolymerization was further activated by the pretreatment with the increase of the depolymerization reaction area of the cured epoxy resin. The activation of such depolymerization occurs not only by increasing the reaction area using physical methods such as grinding, but also by increasing the reaction area through chemical methods such as impregnation methods.

In addition, as can be seen in Table 3, the tensile strength and electrical conductivity of the carbon fiber recovered as a result of Example 6, which does not include the impregnation process, the tensile strength and electrical conductivity of the carbon fiber recovered in Example 8 including the impregnation process It confirmed that it is more excellent. This indicates that the deterioration of the carbon fiber properties that may occur during the depolymerization process is further reduced due to the reduced time taken for depolymerization of the cured epoxy resin through the pretreatment process.

On the other hand, the results obtained by measuring the electrical conductivity of the carbon fibers used in the CFRP of Example 1 of the present invention and the carbon fibers recovered as a result of Example 1 are shown in more detail in Table 4. As can be seen from Table 4, it was confirmed that by decomposing CFRP using the method of the embodiments of the present invention, carbon fibers having 30% improved electrical conductivity can be recovered from CFRP. From the results of the tensile strength measurement and the electrical conductivity measurement, it was confirmed that carbon fiber having excellent physical properties can be recovered from CFRP by decomposing CFRP using the method of the embodiments of the present invention.

[Experiment 2]

As a counter solvent, water and NMP  Use mixed solvent

In Experiment 2, a mixed solvent of water and NMP was used as the reaction solvent, and the dielectric constant was changed by changing the mixing ratio, and the degree of epoxy depolymerization was measured accordingly. The compound used for example sodium hypochlorite. Table 6 shows the experimental conditions and the results.

CFRP
weight Acetic acid
Pretreatment condition NaOCl
Depolymerization reaction
Condition Water: NMP Mixed solvent
permittivity Depolymerization
Before the reaction
Epoxy
content
(%) Depolymerization
After the reaction
Epoxy
content*
(%) Degradation Rate (%) * 0.1 g 120 ℃,
30 minutes 3 M,
70 ml,
90 ℃
0: 100 43 19.4 19.4
(After 24 hours) 0
(After 24 hours) 30:70 51.7 19.4 17.4
(After 24 hours) 10.3
(After 24 hours) 50:50 59.4 19.4 17.3
(After 24 hours) 10.8
(After 24 hours) 60:40 63.8 19.4 17.1
(After 24 hours) 11.8
(After 24 hours) 70:30 68.3 19.4 11.9
(After 24 hours) 38.6
(After 24 hours) 80:20 73.9 19.4 9
(After 24 hours) 53.6
(After 24 hours) 90:10 78.1 19.4 4.7
(After 24 hours) 75.8
(After 24 hours) 100: 0 80.2 19.4 0.0
(After 5 hours) 100
(After 5 hours)

* The content of epoxy resin (cured epoxy resin) before depolymerization of CFRP was 19.4%. The epoxy resin content was measured after 24 hours or 5 hours (if the 100% water already had a significant difference of 0% residual epoxy resin after 5 hours).

* The decomposition rate (depolymerization efficiency) was calculated as follows.

Decomposition ratio = [(epoxy resin content before depolymerization of CFRP-epoxy resin content after depolymerization of CFRP) / epoxy resin content before depolymerization of CFRP] X 100

Water and reaction solvent DMF  Use mixed solvent

Using a mixed solvent of water and DMF as the reaction solvent, the dielectric constant was changed by changing the mixing ratio, and thus the degree of epoxy depolymerization was measured. The compound used sodium hypochlorite. Table 7 shows the experimental conditions and the results.

CFRP
weight Acetic acid
Pretreatment condition NaOCl
Depolymerization reaction
Condition Water: DMF Mixed solvent
permittivity Depolymerization
Before the reaction
Epoxy
content
(%) Depolymerization
After the reaction
Epoxy
content*
(%) Degradation Rate (%) * 0.1 g



120 ℃,
30 minutes



3 M,
70 ml,
90 ℃




0: 100 46.7 19.4 18.8
(After 24 hours) 3
(After 24 hours) 40:60 65.2 19.4 17.3
(After 24 hours) 11
(After 24 hours) 60:40 70.2 19.4 11.6
(After 24 hours) 40
(After 24 hours) 67:33 72.2 19.4 8.7
(After 24 hours) 55
(After 24 hours) 87:13 77.2 19.4 7.0
(After 24 hours) 64
(After 24 hours)

* The content of epoxy resin (cured epoxy resin) before depolymerization of CFRP was 19.4%. The epoxy resin content was measured after 24 hours depolymerization.

* Degradation rate (depolymerization efficiency) was calculated as follows.

Decomposition ratio = [(epoxy resin content before depolymerization of CFRP-epoxy resin content after depolymerization of CFRP) / epoxy resin content before depolymerization of CFRP] X 100

Use of water and acetone mixed solvent as reaction solvent

As a reaction solvent, a mixed solvent of water and acetone was used to change the dielectric constant while changing the mixing ratio, and thus the degree of epoxy depolymerization was measured. The compound used sodium hypochlorite. Table 8 shows the experimental conditions and the results.

CFRP
weight Acetic acid
Pretreatment condition NaOCl
Depolymerization reaction
Condition Water: Acetone Mixed solvent
permittivity Depolymerization
Before the reaction
Epoxy
content
(%) Depolymerization
After the reaction
Epoxy
content*
(%) Degradation Rate (%) * 0.1 g



120 ℃,
30 minutes



3 M,
70 ml,
90 ℃




0: 100 40.3 19.4 19.4
(After 24 hours) 0
(After 24 hours) 35:65 42.9 19.4 17.5
(After 24 hours) 10
(After 24 hours) 65:35 62.5 19.4 16.7
(After 24 hours) 14
(After 24 hours) 75:25 68.6 19.4 13.4
(After 24 hours) 34
(After 24 hours) 88:12 74.8 19.4 9
(After 24 hours) 45
(After 24 hours)

* The content of epoxy resin (cured epoxy resin) before depolymerization of CFRP was 19.4%. The epoxy resin content was measured after 24 hours depolymerization.

* Degradation rate (depolymerization efficiency) was calculated as follows.

Decomposition ratio = [(epoxy resin content before depolymerization of CFRP-epoxy resin content after depolymerization of CFRP) / epoxy resin content before depolymerization of CFRP] X 100

FIG. 9 is a graph showing the depolymerization ratio of the cured epoxy resin according to dielectric constant for each mixed solvent in the exemplary embodiment of the present invention.

As can be seen from this, it can be seen that the slope of the depolymerization efficiency is rapidly increased when the dielectric constant measured at room temperature is about 65 or more. In particular, as shown in the WATER / NMP data, in the case of water alone, the decomposition rate 100 was achieved within 5 hours instead of 24 hours, and compared with the case of mixing with an organic solvent, the rate of decomposition increased dramatically when water alone was used. Showed.

[Experiment 3]

On the other hand, in the present experiment 3, it was tested whether the depolymerization reaction of the cured epoxy resin was promoted when the radical additive was further used.

Example 1 and the comparative example of this Experiment 3 are as follows.

[Example 1: Decomposition of Cured Epoxy Resin in CFRP Using Sodium Hypochlorite (NaOCl) Aqueous Solution and Sodium Percarbonate and Separation of Carbon Fiber]

The epoxy resin cured product used in Example 1 of Experiment 3 was waste CFRP. The waste CFRP consists of an epoxy resin cured product and carbon fiber produced using a curing agent containing an aliphatic amine group and an epoxy compound in the form of diglycidyl ether of bisphenol A.

10.7 g of the waste CFRP and 1 g of sodium percarbonate (2Na ₂ CO ₃ 3H ₂ O ₂ ) were added to 2.5 L of an aqueous 0.4 mol / L sodium hypochlorite solution in a pressurized reactor and stirred at 150 ° C. After 3 hours, the carbon fiber in the aqueous solution was separated and dried.

The thermogravimetric analysis of the recovered carbon fiber is shown in FIG. In addition, the decomposition rate of the cured epoxy resin was calculated using the following equation from the weight change at 300 to 400 degrees shown in the thermogravimetric analysis results, and the results are shown in Table 9.

Comparative Example 1: Decomposition of Cured Epoxy Resin in CFRP Using Sodium Hypochlorite (NaOCl) Aqueous Solution and Separation of Carbon Fiber]

10.7 g of the same waste CFRP as used in Example 1 was used, but in contrast to Example 1 sodium percarbonate (2Na ₂ CO ₃ 3H ₂ O ₂ ) was not used. 2.5 L of 0.4 mol / L sodium hypochlorite aqueous solution contained in a pressurized reactor was added and stirred at 150 ° C. After 3 hours, the carbon fiber in the aqueous solution was separated and dried.

The thermogravimetric analysis of the recovered carbon fiber is shown in FIG. In addition, the decomposition rate of the cured epoxy resin was calculated using the same formula as in Example 1 from the weight change at 300 to 400 degrees shown in the thermogravimetric analysis, and the results are shown in Table 9.

Example 1 Comparative Example 1 Epoxy Content in CFRP 20% 20% Epoxy Residue After Depolymerization 10% 17% Decomposition 50% 15%

10 is a graph showing the depolymerization result of Example 1 when the radical providing additive is added in Experiment 3 of the present invention, and FIG. 11 is a depolymerization of Comparative Example 1 when the radical providing additive is added in Experiment 3 of the present invention. A graph showing the results.

As can be seen from the results of FIGS. 10 and 11 and Table 9, the addition of sodium percarbonate, which is a radical-providing additive, was about 35% higher at the same time, indicating that the depolymerization reaction was promoted by the radical additive. have. Thereby, time and cost for the depolymerization process of hardened | cured epoxy resin can be shortened significantly.

As can be seen from the above, the reaction solvent in the depolymerization composition according to the embodiments of the present invention can be seen that water alone is particularly preferred. When mixing other solvents, including water, a sharp increase in the rate of degradation occurs when the dielectric constant of the mixed solvent measured at room temperature is at least about 65 or more. Subsequently, especially in the case of water alone, the reaction time itself was significantly reduced, showing a dramatic increase in reaction efficiency.

Claims (12)

delete delete delete delete delete delete delete As the epoxy resin cured product depolymerization method,
It is depolymerizing an epoxy resin hardened | cured material using an epoxy resin hardened | cured material dissolution polymerization composition,
The epoxy resin depolymerization composition has a chemical formula XOmYn, wherein X is hydrogen or an alkali metal or an alkaline earth metal, Y is a halogen, m satisfies 1 ≦ m ≦ 8, and n satisfies 1 ≦ n ≦ 6. Compound represented by; And reaction solvents; Including,
The reaction solvent is included, and the H ₂ O based on the reaction solvent is less than a dielectric constant of 65 measured at room temperature H ₂ O,
The compound is HOF, HOCl, HOBr, HOI, NaOF, NaOCl, NaOBr, NaOI, LiOF, LiOCl, LiOBr, LiOI, KOF, KOCl, KOBr, KOI, HO ₂ F, HO ₂ Cl, HO ₂ Br, HO ₂ I , NaO ₂ F, NaO ₂ Cl, NaO ₂ Br, NaO ₂ I, LiO ₂ F, LiO ₂ Cl, LiO ₂ Br, LiO ₂ I, KO ₂ F, KO ₂ Cl, KO ₂ Br, KO ₂ I, Ca (OF) ₂ , Ca (OCl) ₂ , Ca (OBr) ₂ , Ca (OI) ₂ , HO ₃ F, HO ₃ Cl, HO ₃ Br, HO ₃ I, NaO ₃ F, NaO ₃ Cl, NaO ₃ Br , NaO ₃ I, LiO ₃ F, LiO ₃ Cl, LiO ₃ Br, LiO ₃ I, KO ₃ F, KO ₃ Cl, KO ₃ Br, KO ₃ I, HO ₄ F, HO ₄ Cl, HO ₄ Br, HO ₄ I, NaO ₄ F, NaO ₄ Cl, NaO ₄ Br, NaO ₄ I, LiO ₄ F, LiO ₄ Cl, LiO ₄ Br, LiO ₄ I, KO ₄ F, KO ₄ Cl, KO ₄ Br, KO ₄ I , NaOCl ₆ , MgO ₆ F ₂ , MgO ₆ Cl ₂ , MgO ₆ Br ₂ , MgO ₆ I ₂ , CaO ₆ F ₂ , CaO ₆ Cl ₂ , CaO ₆ Br ₂ , CaO ₆ I ₂ , SrO ₆ F ₂ , SrO ₆ Cl ₂ , SrO ₆ Br ₂ , SrO ₆ I ₂ , BaO ₆ F ₂ , BaO ₆ Cl ₂ , BaO ₆ Br ₂ , BaO ₆ I ₂ , NaOCl ₃ , NaOCl ₄ , MgO ₈ Cl ₂ , CaO ₈ Cl ₂ , At least one selected from the group consisting of SrO ₈ Cl ₂ and BaO ₈ Cl ₂ ,
The depolymerization product is a cured epoxy resin depolymerization method comprising a CY (Y is halogen) bond in which Y is bonded to carbon.
The method of claim 8,
Said depolymerization composition is an epoxy resin hardened | cured material depolymerization method characterized by the above-mentioned.
The method of claim 8,
The depolymerization reaction temperature is 20-200 degreeC or 20-100 degreeC, The epoxy resin hardened | cured material depolymerization method characterized by the above-mentioned.
The method of claim 8,
The epoxy resin hardened | cured material depolymerization method characterized by using 1-90 weight part of hardened | cured epoxy resins based on 100 weight part of depolymerization compositions.
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