JPWO2005103131A1 - Decomposition method of thermosetting resin - Google Patents

Abstract

The present invention provides a method for decomposing a thermosetting resin capable of recovering monomers and / or oligomers with high yield, high energy efficiency, and high productivity. Specifically, a thermosetting resin obtained by crosslinking a copolymer of a polyhydric alcohol and an acid with a crosslinking agent is decomposed into a monomer and / or an oligomer using a supercritical or subcritical fluid in the reaction vessel; Generating a gas containing the monomer and / or oligomer by maintaining the reaction liquid at a temperature at which the monomer and / or oligomer evaporates; and recovering the gas to recover the monomer and / or oligomer. A method for decomposing the thermosetting resin.

Description

This patent application claims priority with respect to Japanese Patent Application No. 2004-128814, which is hereby incorporated by reference in its entirety.
The present invention relates to a method for decomposing a thermosetting resin obtained by cross-linking a copolymer composed of a polyhydric alcohol and an acid with a cross-linking agent using a supercritical or subcritical fluid, and recovering the monomer and / or oligomer from the decomposition product.

  Hydrolysis of thermosetting resins using a supercritical fluid or subcritical fluid as a reaction solvent and recovering the produced monomers and / or oligomers can be reused as raw materials for thermosetting resins. Has been done.

For example, a thermosetting resin and a fluid are charged into a reaction vessel, the reaction vessel is sealed and heated to a supercritical temperature or a subcritical temperature, and the fluid is brought into a supercritical or subcritical state, and heated by a supercritical or subcritical fluid. It has been proposed to perform a decomposition reaction of the curable resin and cool the reactant in the reaction vessel to room temperature, then take out the reactant from the reaction vessel and recover the monomer and / or oligomer (for example, , Patent Document 1, Patent Document 2, etc.).
Japanese Patent Laid-Open No. 10-087872 JP-A-10-024274

  However, as described above, after heating to supercritical temperature or subcritical temperature and decomposing the thermosetting resin in the reaction tank, the reaction product is cooled to room temperature and taken out from the reaction tank. The product remains in the reaction vessel for a long time until it is cooled to room temperature. As a result, there is a problem that the yield of recovery of the target monomer and / or oligomer is further degraded and the yield is reduced. Further, in order to cool the reaction product to room temperature and then evaporate and recover the monomer and / or oligomer, there is a problem that the reaction product needs to be heated again, resulting in poor energy efficiency. Furthermore, if the reaction product is taken out by cooling after decomposing the thermosetting resin by heating, decomposition of the thermosetting resin in the reaction tank becomes a batch type. Therefore, the next thermosetting resin cannot be charged into the reaction tank unless the cooling is completed. Moreover, it takes a long time to heat and cool the reaction tank having a high heat capacity. Therefore, there is a problem that the productivity of the decomposition of the thermosetting resin and the recovery of the monomer and / or oligomer is low, and there is a problem that it is inefficient in terms of energy.

  In addition, a thermosetting resin obtained by crosslinking a copolymer of a polyhydric alcohol and an unsaturated organic acid such as an unsaturated polyester with a crosslinking agent such as styrene is subjected to a transesterification reaction using water as a supercritical or subcritical fluid, for example. When decomposed, monomers and / or oligomers such as polyhydric alcohols and unsaturated organic acids, and oligomers which are copolymers of a crosslinking agent and an unsaturated organic acid are generated. Since these are dissolved or dispersed in water, it has been difficult to separate and recover these monomers and / or oligomers from water with high yield, energy efficiency and productivity.

  The present invention has been made in view of the above points, and provides a method for decomposing a thermosetting resin capable of recovering monomers and / or oligomers with high yield, high energy efficiency, and high productivity. For the purpose.

The present invention includes the following inventions.
[1] Decomposing a thermosetting resin obtained by crosslinking a copolymer of a polyhydric alcohol and an acid with a crosslinking agent into monomers and / or oligomers using a supercritical or subcritical fluid in a reaction vessel;
Generating a gas containing the monomer and / or oligomer by maintaining the reaction liquid in the reaction vessel at a temperature at which the monomer and / or oligomer evaporates;
And recovering the monomer and / or oligomer by recovering the gas;
A method for decomposing a thermosetting resin.
[2] The monomer and / or oligomer contained in the gas and the fluid are cooled by cooling the recovered gas to a temperature below the boiling point of the monomer and / or oligomer and above the boiling point of the fluid. The method according to [1] above, comprising separating and recovering the monomer and / or oligomer.
[3] The method according to [2], comprising liquefying the fluid separated from the monomer and / or oligomer and decomposing the thermosetting resin in the reaction tank while returning the liquefied fluid to the reaction tank. the method of.
[4] The method according to [3], including mixing a new thermosetting resin with the liquefied fluid and decomposing the thermosetting resin in the reaction tank while supplying the mixture to the reaction tank. Method.
[5] The method according to [1], including separating and recovering the monomer and / or oligomer contained in the recovered gas from the fluid by an adsorption unit or a membrane separation unit.
[6] The method according to any one of [1] to [5], comprising decomposing the thermosetting resin in the reaction tank while supplying an alkali salt to the reaction tank.
[7] The method according to [3], comprising mixing an alkali salt with the liquefied fluid, and decomposing the thermosetting resin in the reaction tank while supplying the mixture to the reaction tank.
[8] The method according to any one of [1] to [7], comprising decomposing the thermosetting resin in the reaction tank while supplying a fluid to the reaction tank.

  According to the present invention, the monomer and / or oligomer can be taken out from the reaction vessel and recovered without cooling the temperature in the reaction vessel to room temperature. Therefore, it is possible to reduce the decomposition product remaining in the reaction tank for a long time and further decomposition. Further, it is not necessary to perform heating again in order to evaporate and recover the monomer and / or oligomer. Furthermore, the thermosetting resin can be decomposed not continuously but continuously. As a result, the monomer and / or oligomer can be recovered by decomposing the thermosetting resin with high yield, high energy efficiency, and high productivity.

It is a schematic sectional drawing which shows an example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention. It is a schematic sectional drawing which shows another example of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Thermosetting resin 3 Fluid used in a supercritical or subcritical state 4 Monomer and / or oligomer

Hereinafter, the best mode for carrying out the present invention will be described.
In the present invention, the object is a thermosetting resin obtained by crosslinking a copolymer obtained by copolymerizing a polyhydric alcohol and an acid with a crosslinking agent.
Examples of the polyhydric alcohol include glycols such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol, but are not limited thereto. These can also be used in combination.
Examples of the acid include unsaturated organic acids such as aliphatic unsaturated polybasic acids (for example, aliphatic unsaturated dibasic acids such as maleic anhydride, maleic acid, and fumaric acid). It is not limited. These can also be used in combination. Moreover, this unsaturated organic acid and saturated organic acids, such as a phthalic anhydride, can also be used together.
Examples of the crosslinking agent include, but are not limited to, a crosslinking agent having an unsaturated group such as styrene and methyl methacrylate. These can also be used in combination. Moreover, in this invention, the part originating in the said crosslinking agent in the said thermosetting resin is called "crosslinked part." The cross-linked part may be a part derived from one cross-linking agent, or may be a part derived from an oligomer or polymer obtained by polymerizing a plurality of cross-linking agents.
The “thermosetting resin” in the present invention means a resin that has been cured (crosslinked) mainly by heating or the like, but as long as the object of the present invention is achieved, uncured in which curing (crosslinking) proceeds by heating or the like. Alternatively, partially cured resins are also included.
The thermosetting resin may be any form of resin as long as the object of the present invention is achieved. That is, there are no limitations on the type, structure and constituents of the resin, the type, amount and degree of crosslinking of the crosslinking agent, the type and amount of additives, and the like.
Specific examples of the thermosetting resin include, for example, a copolymer obtained by reacting a glycol such as ethylene glycol as a polyhydric alcohol and an unsaturated organic acid such as maleic acid as an acid, and a styrene as a crosslinking agent. Examples thereof include unsaturated polyester resins crosslinked with a crosslinking agent having an unsaturated group.

In the present invention, the thermosetting resin is decomposed by transesterification of the thermosetting resin using a fluid in a supercritical state or a subcritical state (hereinafter collectively referred to as a critical state) as a reaction solvent. For example, it can be carried out by charging the reaction tank with a thermosetting resin and a fluid, heating the reaction tank, and maintaining the temperature and pressure at which the fluid becomes critical in the reaction tank. An example of the fluid used for the reaction in the critical state is water. That is, supercritical water or subcritical water can be used in the present invention.
Here, supercritical water means water in a state exceeding a critical point (critical temperature 374.4 ° C., critical pressure 22.1 MPa). Subcritical water means that the temperature and pressure of water are below the critical point of water, the temperature is 140 ° C. or higher, and the pressure at that time is 0.36 MPa (saturated vapor pressure of 140 ° C.) or higher. It means a certain state of water.

  The reaction conditions when water is used as the fluid are preferably a temperature of 180 to 250 ° C., a pressure of 1.0 to 4.0 MPa, and a reaction time of 1 to 4 hours. Moreover, the ratio of the thermosetting resin with respect to the water of a critical state is 5-100 mass%. Under such conditions, the thermosetting resin can be transesterified (hydrolyzed).

Moreover, an alkali salt can be contained in a fluid (especially water) in a critical state. Since the hydrolysis reaction of the thermosetting resin is promoted by the alkali salt, the treatment time can be shortened and the treatment cost can be reduced. Moreover, when processing a thermosetting resin with the fluid of a critical state, there exists a possibility that the polyhydric alcohol which is a decomposition product may be decomposed | disassembled by the acid catalytic effect of the acid produced | generated simultaneously. When the alkali salt is contained in the fluid in a critical state, the acid can be neutralized by the base of the alkali salt, so that the secondary decomposition can be suppressed.
Here, the “alkali salt” means an alkali metal or alkaline earth metal salt that reacts with an acid and exhibits basic properties, such as potassium hydroxide (KOH) or sodium hydroxide (NaOH). Alkali metal hydroxides, calcium carbonate, barium carbonate, calcium hydroxide, magnesium carbonate, and the like are exemplified, but the invention is not limited thereto. Of these, alkali metal hydroxides are particularly preferred.

The content of the alkali salt in the fluid is not particularly limited, but includes the acid residue derived from the copolymer (polyester) obtained by decomposing the thermosetting resin and the residue derived from the crosslinking portion. It is preferable that it is 2 mol equivalent or more with respect to the theoretical mol number of the acid residue contained in the compound. There exists a possibility that it may become difficult to collect | recover the said compounds as content of an alkali salt is less than 2 molar equivalent. The upper limit of the content of the alkali salt in the subcritical water is not particularly limited, but is preferably 10 molar equivalents or less from the viewpoint of cost.
Here, the compound comprising an acid residue derived from the copolymer and a residue derived from a cross-linked portion is a reaction product of a polybasic acid and a cross-linked portion generated by hydrolysis of the copolymer (polyester). The acid residue includes a residue derived from a polymer obtained by polymerizing the polybasic acid. For example, when the polyester has a fumaric acid residue and the crosslinked portion is a styrene polymer, a styrene-fumaric acid copolymer is obtained as the above compound.
In addition, the theoretical number of moles of acid residues contained in the above compound is the ratio of the number of molecules of acid residues and residues derived from the crosslinking portion obtained by analyzing the compound by NMR, and the crosslinking agent used. This represents the estimated number of moles of acid residues present in the compound, determined from the amount of.

  In the reaction vessel as described above, a thermosetting resin is decomposed using a fluid in a critical state, thereby allowing a monomer such as a polyhydric alcohol (for example, glycol) or an acid (for example, an organic acid), an oligomer or a copolymer thereof. A compound containing an acid residue derived from a residue and a residue derived from a cross-linking moiety can be obtained as a decomposition reaction product with high yield.

  Recovery of monomers and / or oligomers such as polyhydric alcohols and acids from the decomposition reaction product is carried out after the decomposition reaction of the thermosetting resin is completed or during the decomposition reaction, the temperature in the reaction tank is changed by the monomer and / or oligomer. By maintaining the temperature at which it evaporates, a gas containing a monomer and / or oligomer is generated, and the gas can be recovered. When the reaction liquid in which the decomposition reaction product in the reaction tank and the fluid are mixed is maintained at a temperature at which the monomer and / or oligomer evaporates, the monomer and / or oligomer (and fluid) evaporate from the reaction liquid. A gas containing oligomers is generated. By recovering this gas, monomers and / or oligomers can be recovered.

The temperature at which the monomer and / or oligomer evaporates in the present invention is not particularly limited as long as the temperature at which the monomer and / or oligomer evaporates, and may be appropriately selected depending on the type of monomer and / or oligomer and the type of fluid used. it can. For example, it is 150-230 degreeC, Preferably it is the temperature more than the boiling point of this monomer and / or oligomer. For example, when ethylene glycol and maleic anhydride are obtained as monomers, the boiling point of ethylene glycol is 197 ° C. and the boiling point of maleic anhydride is 202 ° C .;
The temperature may be lower than the boiling point of the monomer and / or oligomer when the fluid azeotropes with the monomer and / or oligomer. That is, the temperature can be higher than the azeotropic point of the monomer and / or oligomer and the fluid.
The upper limit of the temperature is not particularly set, but is preferably set to 230 ° C. or lower so that components other than these recovered monomers and / or oligomers (and fluid) do not evaporate.
In addition, the recovery of the gas containing the monomer and / or oligomer in the present invention can be performed at any time as long as the temperature of the reaction solution is maintained at the temperature at which the monomer and / or oligomer evaporates. For example, during the decomposition reaction, it can be performed for a predetermined time (for example, 1 hour) after the end of the decomposition reaction.

  According to the present invention, the monomer and / or oligomer is long in the reaction tank until it is cooled to room temperature, as in the case where the decomposition product and fluid mixture in the reaction tank is cooled to room temperature and removed from the reaction tank. You can avoid staying in time. Therefore, it can be prevented that the decomposition reaction further proceeds and the monomer and / or oligomer is destroyed and the recovery rate of the monomer and / or oligomer is lowered. In addition, in order to recover the monomer and / or oligomer, it is only necessary to maintain the temperature at which the monomer and / or oligomer evaporates. Therefore, the monomer and / or oligomer is evaporated after the reaction product is cooled to room temperature. Therefore, the required energy is greatly reduced compared to the case where heating is performed again. Therefore, the monomer and / or oligomer can be recovered with energy efficiency.

The gas containing the monomer and / or oligomer generated as described above is usually a mixed gas of the monomer and / or oligomer and the fluid used in the reaction. By cooling the gas to a temperature below the boiling point of the monomer and / or oligomer and above the boiling point of the fluid, the monomer and / or oligomer can be separated from the fluid and recovered. This can be performed, for example, by providing a cooling device for cooling the gas in a recovery path (for example, recovery piping) of the gas discharged from the reaction tank (see FIGS. 2 to 7 and 9 to 12). This is because when the gas is placed in the temperature range, the monomer and / or oligomer in the gas is liquefied, but the fluid is not liquefied. Compared to the case where the gas generated from the reaction vessel is once cooled and liquefied and then heated again to fractionate the monomer and / or oligomer and the fluid, the monomer and / or oligomer is more energy efficient than the fluid. It can be separated and recovered.
The temperature below the boiling point of the monomer and / or oligomer and above the boiling point of the fluid can be appropriately selected depending on the type of fluid used and the type of monomer and / or oligomer. For example, 100-150 degreeC is mentioned. For example, when the fluid is water and ethylene glycol (boiling point: 197 ° C) and maleic anhydride (boiling point: 202 ° C) are obtained as monomers, the temperature can be set to 100 to 150 ° C.

  The monomer and / or oligomer can be separated from the mixed gas of the monomer and / or oligomer and fluid using an adsorption means or a membrane separation means. This can be performed, for example, by providing an adsorption means or a membrane separation means in a recovery path (for example, recovery piping) of the gas discharged from the reaction tank (see FIG. 8). For example, by passing a mixed gas of monomer and / or oligomer and fluid through an adsorbing means (for example, an adsorbent such as a nitrogen adsorbent), adsorbing the fluid in the gas to the adsorbing means, or By adsorbing the monomer and / or oligomer in the mixed gas to the adsorption means, the monomer and / or oligomer can be recovered in a state separated from the fluid. Further, when a membrane separation means (for example, a separation membrane such as a gas separation membrane) is used, only the monomer and / or oligomer is not allowed to pass through the fluid in the mixed gas of monomer and / or oligomer and fluid. The monomer and / or oligomer is recovered in a state separated from the fluid by passing the membrane through the membrane or by passing the membrane only through the fluid without passing the membrane through the monomer and / or oligomer in the mixed gas. be able to. Thus, by separating the monomer and / or oligomer from the fluid by means of adsorption separation or membrane separation, more efficient separation can be performed than when separating using a difference in boiling points.

When the monomer and / or oligomer of the decomposition product is recovered as described above, the used fluid also flows out from the reaction vessel as a gas, so the amount of fluid in the reaction vessel is also reduced. Accordingly, the reaction solution in the reaction tank has a high concentration and a high viscosity of a decomposition product of the thermosetting resin (for example, a compound containing an acid residue derived from a copolymer and a residue derived from a cross-linked portion). . As a result, the decomposition product may adhere to the inner wall and become charred, making recovery difficult. Moreover, when the thermosetting resin containing an inorganic substance is decomposed | disassembled, an inorganic substance precipitates. It is difficult to recover the monomer and / or oligomer attached to the inorganic substance. In order to solve such a problem, the decomposition reaction can be performed while supplying a fluid to the reaction tank. In this case, the decomposition reaction can be performed while maintaining a constant amount of fluid in the reaction vessel.
This can be performed, for example, by providing a fluid supply means (for example, a liquid supply pump) in the reaction tank (see FIG. 11). For example, after performing a decomposition reaction (preferably 1 to 4 hours) during which the thermosetting resin is sufficiently decomposed, a gas containing a monomer and / or oligomer is recovered from the reaction vessel. At the same time, the fluid is fed into the reaction tank through the fluid supply means so that the amount of fluid in the reaction tank becomes a predetermined amount. In this case, the amount of decrease in the fluid in the reaction tank can be grasped from the amount of fluid recovered in the recovery container, and the fluid can be sent to the reaction tank in accordance with the amount of decrease.
Further, the above method includes a fluid amount measuring means (for example, a flow rate sensor) for measuring the amount of fluid in the reaction tank, and a fluid supply means (for example, a liquid sensor) for supplying fluid to the reaction tank according to the fluid amount. It can also be performed by providing a supply pump) in the reaction tank (see FIG. 12). For example, a liquid supply pump, a flow sensor for measuring the amount of fluid in the reaction tank, and a controller that receives the signal from the flow sensor and sends a signal to the liquid supply pump to control the liquid supply pump are provided in the reaction tank. When the amount of fluid in the reaction vessel measured by the flow sensor becomes a predetermined amount or less, the liquid supply pump is operated through the controller so that the fluid is fed into the reaction vessel.
Moreover, in order to efficiently separate the monomer and / or oligomer from the precipitated inorganic substance in the reaction tank, the supply of the fluid by the fluid supply means to the reaction tank effectively stirs the reaction liquid in the reaction tank. It is preferable to carry out from the lower part of the reaction tank (lower half of the reaction tank. The closer to the bottom of the reaction tank, the better).
In this way, when the decomposition reaction is performed while supplying the fluid to the reaction tank, the decomposition reaction can be performed with the amount of fluid in the reaction tank being substantially constant. In addition, decomposition products and the like can be prevented from adhering to the inner wall and scorching. Furthermore, the monomer and / or oligomer adhering to the precipitated inorganic substance in the reaction tank can be separated and dissolved in the fluid. Since the monomer and / or oligomer moves to the upper part of the reaction tank together with the fluid and evaporates, it can be recovered. Therefore, the recovery rate of the monomer and / or oligomer can be increased.

The fluid separated from the monomers and / or oligomers can be released, but can be circulated and reused by returning it to the reaction vessel. This can be performed, for example, by providing means (for example, a return pipe, a pump, etc.) for returning the fluid in the gas discharged from the reaction tank to the reaction tank (see FIGS. 3 to 5, 7 and 10). In this case, it is possible to prevent the efficiency of the decomposition reaction of the thermosetting resin from being reduced by reducing the amount of the fluid in the critical state in the reaction tank. In addition, since the monomer and / or oligomer remaining without being separated in the fluid can also be returned to the reaction vessel, it can be recovered again.
The fluid can be returned in the form of a gas, but it is preferable that the fluid be liquefied and in a liquid state, pressurized as necessary and returned to the reaction vessel. When returning the fluid to the reaction vessel in a liquid state, it can be circulated efficiently. The fluid liquefaction method is not particularly limited, and examples thereof include a method of cooling the fluid below its boiling point using a cooling device or the like (see FIGS. 5, 7 and 10).
In addition, the fluid to be returned can be used for stirring the reaction solution in the reaction tank. This can be performed, for example, by placing the tip of the end connected to the reaction tank of the fluid return pipe below the level of the reaction solution (see FIG. 4).

  The recovery of the produced monomer and / or oligomer in the present invention can be performed not only after the decomposition reaction of the thermosetting resin but also during the decomposition reaction. When the generated monomer and / or oligomer is recovered after the decomposition reaction is completed, the monomer and / or oligomer recovery rate is reduced as a result of secondary decomposition of the monomer and / or oligomer generated at the beginning of the decomposition reaction. There is a risk of doing. However, when recovering the generated monomer and / or oligomer while performing the decomposition reaction, the generated monomer and / or oligomer can be immediately discharged from the high-temperature reaction tank and recovered, preventing secondary decomposition. Thus, the recovery rate can be improved. The embodiment of the present invention for recovering the monomer and / or oligomer produced while carrying out the decomposition reaction may be carried out, for example, using an apparatus in which a closed system as shown in FIGS. 3 to 7 and 10 described later is formed. it can.

When recovering the monomer and / or oligomer of the decomposition product while decomposing the thermosetting resin in the reaction vessel as described above, the thermosetting resin in the reaction vessel is gradually reduced and the fluid used is also Since it flows out as gas, the amount of fluid in the reaction vessel is also reduced.
Therefore, a mixed slurry of the liquid fluid used in the critical state and the pulverized thermosetting resin can be supplied to the reaction vessel. This can be performed, for example, by providing means (pump, piping, etc.) for supplying the mixed slurry in the reaction tank (see FIGS. 6 and 7). Further, the fluid separated from the monomer and / or oligomer as described above can be returned to the reaction vessel, and a thermosetting resin can be supplied to the reaction vessel. This can be performed, for example, by providing a means for mixing and storing the fluid to be returned to the reaction tank and the pulverized resin (mixer tank, etc.) and means for supplying the mixed slurry in the reaction tank ( (See FIG. 7).
In this case, the operation of decomposing the thermosetting resin and recovering the monomer and / or oligomer for a long time can be continued. That is, decomposition of the thermosetting resin and recovery of the monomer and / or oligomer can be performed as a continuous process instead of a batch process. Therefore, decomposition of the thermosetting resin and recovery of the monomer and / or oligomer can be performed with high productivity. Furthermore, since the ratio of the temperature raising time required for starting up the operation and the ratio of the cooling time required for completing the operation can be reduced, the production efficiency can be increased.

In order to accelerate the decomposition reaction of the thermosetting resin and avoid adverse effects (decomposition of polyhydric alcohol as a monomer, etc.) due to the acid generated by the decomposition reaction of the thermosetting resin, an alkali salt is added to the fluid in the critical state. The decomposition reaction can also be carried out while feeding. In this case, the decomposition reaction is carried out while maintaining the pH of the fluid in the reaction tank in a range where no adverse effects are caused by the acid (for example, alkaline, preferably the pH is in the range of 10-14, particularly preferably in the range of 13-14). Can do. Therefore, decomposition of the thermosetting resin and recovery of the monomer and / or oligomer can be performed with high productivity.
This can be performed, for example, by providing an alkali salt supply means (for example, a pump) for supplying an alkali salt to the reaction tank. For example, after a certain period of time (for example, 1 to 4 hours), a predetermined amount of alkali salt is fed into the reaction tank according to the measured or predicted consumption of the alkali salt due to the decomposition reaction.
In addition, the above method includes a pH measuring means (for example, a pH sensor) for measuring the pH of the fluid in the reaction tank, and an alkali salt supplying means (for example, for supplying an alkali salt to the reaction tank according to the pH). A pump) can be provided in the reaction tank (see FIG. 10). For example, a pump for supplying alkali salt to the reaction tank, a pH sensor for measuring the pH of the fluid in the reaction tank, a pH control for receiving a signal from the pH sensor and sending a signal to the pump to control the pump A vessel is provided in the reaction vessel. When the pH of the fluid in the reaction vessel measured by the pH sensor falls below a predetermined value, the pump is operated through a pH controller to feed an alkali salt solution into the reaction vessel. In this case, the pH of the fluid in the reaction tank can be confirmed at any time, and an alkali salt can be supplied into the reaction tank at any time according to the pH. Therefore, since the pH of the fluid in the reaction tank can always be maintained within a predetermined range, the thermosetting resin is efficiently decomposed over a long period of time, and the recovery rate of the monomer and / or oligomer is increased. Can do.
Furthermore, the fluid from which the monomer and / or oligomer has been removed as described above can be returned to the reaction tank, and an alkali salt can be supplied to the reaction tank. This can be performed, for example, by providing the reaction tank with means (storage tank or the like) for mixing and storing the fluid to be returned to the reaction tank and the alkali salt and the alkali salt supply means (see FIG. 10). By circulating the fluid excluding the monomer and / or oligomer, it is possible to avoid further degradation of the monomer and / or oligomer by the alkali salt.

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an example of an embodiment of the present invention. A recovery port 6 is provided at the top of the pressure-resistant reaction tank 1 and a discharge port 7 is provided at the bottom. The recovery port 6 is provided with a pressure release on-off valve 8, and the discharge port 7 is provided with a discharge on-off valve 9. A heating device 10 formed by a heat exchanger or the like is provided around the reaction vessel 1. By circulating the heat medium in the heating device 10 with the pump 11, the inside of the reaction tank 1 can be heated while being controlled to a predetermined temperature.

  In decomposing the thermosetting resin, the thermosetting resin 2 and the fluid 3 are charged into the reaction tank 1, the reaction tank 1 is sealed and heated by the heating device 10, and the fluid 3 is in a critical state in the reaction tank 1. By maintaining the temperature and pressure at which the thermosetting resin 2 becomes, the thermosetting resin 2 can be transesterified using the critical fluid 3 as a reaction solvent.

  In recovering the polyhydric alcohol or acid monomer and / or oligomer from the reaction product obtained by decomposing the thermosetting resin 2, after the decomposition reaction of the thermosetting resin 2, the heating device 10 is changed. The temperature in the reaction tank 1 is controlled and maintained at a temperature at which the monomer and / or oligomer evaporates (for example, 150 to 230 ° C.), and the on-off valve 8 of the recovery port 6 is opened. When the recovery port 6 of the reaction tank 1 is opened in such a state that the monomer and / or oligomer is evaporated at a temperature (for example, a temperature equal to or higher than the boiling point thereof), the decomposition reaction product and the fluid 3 in the reaction tank 1 are opened. The monomer and / or oligomer evaporates from the reaction liquid in which is mixed, and the gas containing the monomer and / or oligomer is discharged from the recovery port 6. By recovering this gas, monomers and / or oligomers can be recovered. In this way, reaction products such as a polymer of a cross-linking agent (for example, styrene) and an acid (for example, phthalic acid) remaining in the reaction tank 1 after recovering the gas, undecomposed resin, and the like can be opened and closed by the opening / closing valve 9 of the discharge port 7. It can be recovered by opening and dispensing from the reaction vessel 1.

  FIG. 2 shows another example of the embodiment of the present invention. A recovery pipe 13 is connected to the recovery port 6 of the reaction tank 1, and a cooling device 14 is provided in the recovery pipe 13. The cooling device 14 can circulate refrigerant and the like to cool the gas passing through the recovery pipe 13. Other configurations are the same as those of the apparatus shown in FIG.

  In the apparatus of FIG. 2, as described above, after the thermosetting resin 2 is decomposed and reacted using the fluid 3 in the critical state in the reaction tank 1, the temperature in the reaction tank 1 is changed to the monomer and / or oligomer. When the on-off valve 8 of the recovery port 6 is opened while maintaining the temperature to evaporate, the monomer and / or oligomer evaporates from the reaction solution in which the decomposition reaction product in the reaction tank 1 and the fluid 3 are mixed. Since the boiling point of the fluid 3 such as water used in a critical state is generally lower than the temperature at which the monomer and / or oligomer evaporates, the mixed gas of the monomer and / or oligomer gas and the fluid 3 gas is discharged from the recovery port 6. Is done. The cooling device 14 is set to a temperature that is lower than the boiling point of the monomer and / or oligomer and higher than the boiling point of the fluid 3 (for example, 100 to 150 ° C.), whereby the monomer and / or oligomer and the fluid 3 are set. When the mixed gas passes through the recovery pipe 13, the monomer and / or oligomer is liquefied but the fluid 3 is not liquefied, so that the monomer and / or oligomer can be separated from the fluid 3. A recovery container 15 is disposed at the tip of the recovery pipe 13, and the liquefied monomer and / or oligomer 4 flows into the recovery container 15 and is recovered. The fluid 3 may be discharged as a gas.

  FIG. 3 shows another example of the embodiment of the present invention. A fluid return pipe 17 is provided between the recovery container 15 and the reaction tank 1. The fluid return pipe 17 is provided with a pump 18, and one end of the fluid return pipe 17 is hermetically connected to the upper part of the reaction tank 1. The other end of the fluid return pipe 17 is hermetically connected to a position above the liquid level of the liquid monomer and / or oligomer 4 in the recovery container 15. The collection container 15 is formed in a sealed structure. In this embodiment, the heating device 10 is formed by a heater or the like, but the other configuration is the same as the device of FIG.

  In the apparatus of FIG. 3, as described above, the monomer and / or oligomer 4 is liquefied and recovered in the recovery container 15 by cooling the gas emerging from the recovery port 6 of the reaction tank 1 with the cooling device 14. be able to. On the other hand, the fluid 3 flows into the recovery container 15 as a gas. With the action of the pump 18, the fluid 3 in the recovery container 15 is sucked into the fluid return pipe 17 in a gaseous state and returned to the reaction tank 1. In the apparatus of FIG. 3, a sealed system is formed between the reaction tank 1 and the recovery container 15 through the recovery pipe 13 and the fluid return pipe 17 even when the on-off valve 8 of the recovery port 6 is kept open. Therefore, the high pressure in the reaction tank 1 can be maintained. As a result, a gas is caused to flow out from the recovery port 6 of the reaction tank 1 while the thermosetting resin 2 is decomposed in the reaction tank 1 under a high temperature and high pressure condition in a critical state, and this gas is cooled by the cooling device 14. Thus, the monomer and / or oligomer 4 can be liquefied, and the liquid monomer and / or oligomer 4 can be separated and recovered in the recovery container 15. At the same time, the gas of the fluid 3 can be returned from the recovery container 15 to the reaction tank 1 through the fluid return pipe 17.

  When recovering the monomer and / or oligomer 4 generated after the completion of the decomposition reaction of the thermosetting resin 2 as in the embodiment of FIGS. 1 and 2, the monomer and / or oligomer generated at the initial stage of the decomposition reaction 4 is subject to secondary decomposition, and the recovery rate of the monomer and / or oligomer 4 may decrease. However, when the decomposed monomer and / or oligomer 4 is recovered while performing the decomposition reaction of the thermosetting resin 2 in the reaction vessel 1 in this manner, the generated monomer and / or oligomer 4 is immediately reacted at a high temperature. Since it can discharge | emit and collect | recover from the tank 1, secondary decomposition | disassembly can be prevented and a collection rate can be improved. Moreover, since the fluid 3 is always returned to the reaction tank 1, it is possible to prevent the amount of the fluid 3 in the critical state in the reaction tank 1 from being reduced and the efficiency of the decomposition reaction of the thermosetting resin 2 from being lowered. it can. Even if monomers and / or oligomers remain in the fluid 3 without being separated, the monomers and / or oligomers are also returned to the reaction tank 1 so that they can be recovered again.

  FIG. 4 shows another example of the embodiment of the present invention. The tip of the end connected to the reaction tank 1 of the fluid return pipe 17 is positioned below the liquid level of the liquid mixture of the fluid 3 and the thermosetting resin 2 in the critical state of the reaction tank 1. Other configurations are the same as those of the apparatus shown in FIG.

  In this apparatus, the fluid 3 is returned in a gaseous state by being blown out into a mixed liquid of the fluid 3 and the thermosetting resin 2 in a critical state through the fluid return pipe 17. With the fluid 3 returned, the liquid mixture of the fluid 3 and the thermosetting resin 2 in the critical state can be stirred. Therefore, the efficiency of the decomposition reaction of the thermosetting resin 2 can be increased. The reaction tank 1 in which the thermosetting resin 2 is decomposed and reacted with the fluid 3 in a critical state is at a high pressure. It is difficult to provide a stirring mechanism such as a rotary blade in the reaction tank 1 so that this high pressure is maintained, and the apparatus becomes complicated and expensive. On the other hand, by using the fluid 3 to be returned as described above, the reaction tank 1 can be stirred without providing a stirring mechanism.

  FIG. 5 shows another example of the embodiment of the present invention. A recovery pipe 13 provided with the above-described cooling device 14 is connected to the recovery port 6 of the reaction tank 1. A fluid cooling device 20 is provided at a position farther from the recovery port 6 than the cooling device 14 of the recovery pipe 13. A refrigerant or the like is circulated in the fluid cooling device 20, and the gas passing through the recovery pipe 13 can be cooled at a temperature lower than the boiling point of the fluid 3. A recovery branch pipe 21 is connected to the recovery pipe 13 at a position between the cooling device 14 and the fluid cooling apparatus 20, and the recovery branch pipe 21 is connected to the recovery container 15. The end of the recovery pipe 13 opposite to the recovery port 6 is connected to the fluid recovery container 22. One end of the fluid return pipe 17 is connected to the bottom of the fluid recovery container 22, and the other end of the fluid return pipe 17 is connected to the top of the reaction tank 1. The fluid return pipe 17 is provided with a pump 23 for feeding liquid. The recovery pipe 13 is connected to the reaction tank 1, the recovery container 15 and the fluid recovery container 22, and the fluid return pipe 17 is connected to the reaction tank 1 and the fluid recovery container 22 in an airtight manner. Accordingly, a sealed system is formed that can maintain the high pressure in the reaction tank 1 even when the on-off valve 8 of the recovery port 6 is kept open. Other configurations are the same as those of the apparatus shown in FIG.

  In the apparatus of FIG. 5, as in the case of FIGS. 3 and 4, thermosetting is performed in the reaction tank 1 under high temperature and high pressure conditions in which the fluid 3 becomes a critical state with the on-off valve 8 of the recovery port 6 opened. The decomposition reaction of the functional resin 2 can be performed. Further, by cooling the gas coming out from the recovery port 6 of the reaction tank 1 to the recovery pipe 13 to a temperature below the boiling point of the monomer and / or oligomer and above the boiling point of the fluid 3 by the cooling device 14, The monomer and / or oligomer 4 can be liquefied and recovered in the recovery container 15 through the recovery branch pipe 21. The fluid 3 passes through the cooling device 14 of the recovery pipe 13 in the form of gas. By cooling to a temperature below the boiling point of the fluid 3 by the fluid cooling device 20, the fluid 3 becomes liquid and flows into the fluid recovery container 22. The liquid fluid 3 in the fluid recovery container 22 is pressurized by the pump 23 and returned to the reaction tank 1 through the fluid return pipe 17.

  According to the apparatus of FIG. 5, the gas is caused to flow out from the recovery port 6 of the reaction tank 1 while performing the decomposition reaction of the thermosetting resin 2 under the high temperature and high pressure conditions in which the fluid 3 becomes a critical state in the reaction tank 1. This gas can be cooled by the cooling device 14 to liquefy the monomer and / or oligomer 4 and be separated and recovered in the recovery container 15. At the same time, the fluid 3 can be cooled and liquefied by the fluid cooling device 20, and the liquid fluid 3 can be returned from the fluid recovery container 22 to the reaction tank 1 through the fluid return pipe 17. Then, by pumping the fluid 3 using the pump 23 in a liquefied state, the flow rate can be controlled more easily than when the fluid 3 is returned, so that the fluid 3 can be returned efficiently.

  FIG. 6 shows another example of the embodiment of the present invention. One end of a recovery pipe 13 provided with a cooling device 14 is connected to the recovery port 6 of the reaction tank 1, and the other end of the recovery pipe 13 is connected to a recovery container 15. A liquid supply pipe 25 is connected to the upper part of the reaction tank 1, and a liquid supply pump 26 is provided in the liquid supply pipe 25. The recovery pipe 13 is airtightly connected to the reaction tank 1 and the recovery container 15 respectively. Also, the liquid supply pipe 25 is kept airtight by the liquid supply pump 26. Accordingly, a sealed system is formed that can maintain the high pressure in the reaction tank 1 even when the on-off valve 8 of the recovery port 6 is kept open. Other configurations are the same as those of the apparatus shown in FIG.

  In the apparatus of FIG. 6, as in FIGS. 3 to 5, thermosetting is performed in the reaction tank 1 under high temperature and high pressure conditions in which the fluid 3 becomes a critical state with the on-off valve 8 of the recovery port 6 opened. The decomposition reaction of the functional resin 2 can be performed. Further, by cooling the gas coming out from the recovery port 6 of the reaction tank 1 to the recovery pipe 13 with the cooling device 14, the monomer and / or oligomer 4 can be made liquid and recovered into the recovery container 15 through the recovery pipe 13. it can. When the monomer and / or oligomer 4 of the decomposition product is recovered from the recovery port 6 while decomposing the thermosetting resin 2 in the reaction tank 1 as described above, the thermosetting resin 2 in the reaction tank 1 gradually decreases. At the same time, since the fluid 3 in the critical state also flows out from the recovery port 6 as a gas, the amount of the fluid 3 in the reaction tank 1 also decreases. Therefore, a mixed slurry of the liquid fluid 3 used in the critical state and the pulverized thermosetting resin 2 is supplied from the liquid supply pipe 25 to the reaction tank 1 by the liquid supply pump 26. Thus, by supplying the fluid 3 and the thermosetting resin 2, by performing a decomposition reaction of the thermosetting resin 2 in the reaction tank 1, the thermosetting resin 2 is decomposed over a long period of time to decompose the monomer and The operation of recovering the oligomer 4 can be continued. Therefore, the ratio of the temperature raising time required for starting up the operation and the cooling time required for completing the operation is reduced, and the production efficiency can be increased.

  In addition to supplying the mixed slurry of the liquid fluid 3 and the thermosetting resin 2 as described above, while supplying only the fluid such as water used in the critical state from the liquid supply pipe 25 in the liquid state, You may make it perform the decomposition reaction of the thermosetting resin 2 in the reaction tank 1. FIG. When the decomposition product monomer and / or oligomer 4 is recovered from the recovery port 6 while decomposing the thermosetting resin 2 in the reaction tank 1, the critical fluid 3 also flows out from the recovery port 6 as a gas. The amount of the fluid 3 in the tank 1 decreases, and the efficiency of the decomposition reaction of the thermosetting resin gradually decreases. By carrying out the decomposition reaction of the thermosetting resin 2 in the reaction tank 1 while supplying the fluid 3 in this way, the decomposition reaction of the thermosetting resin 2 can be maintained with high efficiency. At this time, a liquid supply pump 26 having a low capacity and a simple structure can be used as compared with a case where a mixed slurry of the fluid 3 and the thermosetting resin 2 is supplied.

  FIG. 7 shows another example of the embodiment of the present invention. Similar to the embodiment of FIG. 5, a recovery pipe 13 provided with a cooling device 14 and a fluid cooling device 20 is connected to the recovery port 6 of the reaction tank 1. A recovery branch pipe 21 branched and connected to the recovery pipe 13 is connected to the recovery container 15. The end of the recovery pipe 13 is connected to the fluid recovery container 22. A mixer tank 28 is connected to the upper part of the reaction tank 1 by a supply pipe 29. One end of the fluid return pipe 17 is connected to the bottom of the fluid recovery container 22, and the other end of the fluid return pipe 17 is connected to the mixer tank 28. The fluid return pipe 17 is provided with a pump 23 for feeding liquid. The mixer tank 28 mixes and stores the fluid 3 and the pulverized product of the thermosetting resin 2. The recovery pipe 13 is connected to the reaction tank 1, the recovery container 15 and the fluid recovery container 22, the fluid return pipe 17 is connected to the fluid recovery container 22 and the mixer tank 28, and the supply pipe 29 of the mixer tank 28 is connected to the reaction tank 1 in an airtight manner. Connected. Accordingly, a sealed system is formed that can maintain the high pressure in the reaction tank 1 even when the on-off valve 8 of the recovery port 6 is kept open. Other configurations are the same as those of the apparatus shown in FIG.

  In the apparatus of FIG. 7, as in the case of FIGS. 3 to 6, with the open / close valve 8 of the recovery port 6 opened, thermosetting is performed in the reaction tank 1 under high temperature and high pressure conditions in which the fluid 3 becomes a critical state. The decomposition reaction of the functional resin 2 can be performed. In addition, the monomer and / or oligomer 4 in the gas can be liquefied and recovered in the recovery container 15 by cooling the gas coming out from the recovery port 6 of the reaction tank 1 to the recovery pipe 13 with the cooling device 14. . Further, by cooling the fluid 3 in the gas with the fluid cooling device 20, the fluid 3 can be liquefied and recovered in the fluid recovery container 22. The liquid fluid 3 in the fluid recovery container 22 is pressurized by the pump 23 and returned to the mixer tank 28 through the fluid return pipe 17. Thus, the fluid 3 returned to the mixer tank 28 is mixed with the pulverized thermosetting resin 2, and this mixed slurry is supplied to the reaction tank 1 through the supply pipe 29. Thus, by returning the fluid 3 to the reaction vessel 1 in a state of being mixed with the thermosetting resin 2, the amount of the thermosetting resin 2 and the fluid 3 in the reaction vessel 1 is always kept constant, and the amount of time is increased. The operation of decomposing the thermosetting resin 2 and recovering the monomer and / or oligomer 4 can be continued. In addition, by circulating the fluid 3, even if the monomer and / or oligomer remain in the fluid 3 without being separated, the monomer and / or oligomer is also returned to the reaction tank 1, so that the recovery is performed again. Can do.

  FIG. 8 shows another example of the embodiment of the present invention. A recovery pipe 13 is connected to the recovery port 6 of the reaction tank 1, and a separation / recovery device 31 is provided in the recovery pipe 13. In the separation / recovery device 31, there are provided adsorption means made of an adsorbent such as nitrogen adsorbent, or membrane separation means made of a separation membrane such as a gas separation membrane. Other configurations are the same as those of the apparatus shown in FIG.

  In the apparatus of FIG. 8, after the thermosetting resin 2 is decomposed and reacted in the reaction tank 1 using the fluid 3 in the critical state, the temperature in the reaction tank 1 is maintained at the temperature at which the monomer and / or oligomer evaporates. Then, when the on-off valve 8 of the recovery port 6 is opened, the monomer 3 and / or oligomer gas and the fluid 3 such as water used in the critical state are mixed from the mixture of the decomposition reaction product in the reaction tank 1 and the fluid 3. Vapor containing gas comes out of the recovery port 6. When the separation / recovery device 31 is provided with an adsorbing means, when the mixed gas of the monomer and / or oligomer and the fluid 3 passes through the separation / recovery device 31 through the recovery pipe 13, the fluid 3 in the mixed gas Since the gas can be adsorbed by the adsorbing means, the monomer and / or oligomer 4 coming out from the recovery pipe 13 can be recovered in a state separated from the fluid 3. Alternatively, the monomer and / or oligomer 4 in a state separated from the fluid 3 can be recovered by adsorbing the monomer and / or oligomer 4 gas in the mixed gas to the adsorption means. Further, when the separation and recovery device 31 is provided with a membrane separation means, the membrane can be passed only to the monomer and / or oligomer gas without passing the membrane through the gas of the fluid 3 in the mixed gas, The monomer and / or oligomer coming out of the recovery pipe 13 can be recovered in a state separated from the fluid 3. Alternatively, the monomer and / or oligomer 4 in a state separated from the fluid 3 is recovered by allowing the monomer and / or oligomer 4 gas in the mixed gas not to pass through the membrane but only the fluid 3 gas to pass through the membrane. be able to. By separating the monomer and / or oligomer from the fluid 3 by means of adsorption separation or membrane separation in this way, more efficient separation can be performed than when separating by fractional distillation using a boiling point difference.

  FIG. 9 shows another example of the embodiment of the present invention. A plurality of reaction vessels 1 are used. As in FIG. 2, a recovery pipe 13 is connected to the recovery port 6 of one of the reaction tanks 1 a and 1 b, and a cooling device 14 is provided in the recovery pipe 13. Similarly, a recovery pipe 13 is connected to the recovery port 6 of the other reaction tank 1b. The recovery pipe 13 is provided with a heat exchanger 33 instead of the cooling device 14. A heating device 10 formed of a heat medium pipe 34 or the like is provided around each reaction tank 1a, 1b. While heating the heating medium in the heating medium pipe 34 with the heater 35, the heating medium is circulated along the heating medium pipe 34 by the pump 11, thereby heating the inside of the reaction tank 1 while controlling it at a predetermined temperature. it can. A part of the heat medium pipe 34 of the heating apparatus 10 provided in one reaction tank 1a is arranged as a heat exchange unit 36 in a heat exchanger 33 provided in the other reaction tank 1b. The heat exchange unit 36 is set at a position upstream of the heater 35 in the flow of the heat medium in the heat medium pipe 34. Other configurations are the same as those of the apparatus shown in FIG.

  In the apparatus of FIG. 9, the thermosetting resin 2 can be decomposed and reacted using the fluid 3 in a critical state in each of the reaction tanks 1a and 1b. And after the decomposition reaction of the thermosetting resin 2 in one reaction tank 1a is complete | finished, the monomer and / or oligomer produced | generated by decomposition | disassembly of the thermosetting resin 2 evaporate the temperature in this reaction tank 1a. When the on-off valve 8 of the recovery port 6 is opened while maintaining the temperature, the monomer and / or oligomer and the fluid 3 evaporate from the mixture of the decomposition reaction product and the fluid 3 in the reaction tank 1, and the monomer and / or oligomer A mixed gas of the gas and the fluid 3 comes out from the recovery port 6. The mixed gas is cooled by the cooling device 14 at a temperature below the boiling point of the monomer and / or oligomer and above the boiling point of the fluid 3. As a result, the monomer and / or oligomer is liquefied and fractionated from the gaseous fluid 3, and the liquefied monomer and / or oligomer 4 flows from the recovery pipe 13 into the recovery container 15 and is recovered. In the other reaction tank 1 b, when the open / close valve 8 is opened and a mixed gas of the monomer and / or oligomer gas and the fluid 3 gas comes out of the recovery port 6, the mixed gas is transferred by the heat exchanger 33. And cooled at a temperature below the boiling point of the monomer and / or oligomer and above the boiling point of the fluid 3. As a result, the monomer and / or oligomer is liquefied and fractionated from the gaseous fluid 3, and the liquefied monomer and / or oligomer 4 flows from the recovery pipe 13 into the recovery container 15 and is recovered.

  As described above, in the heat exchanger 33 provided in the other reaction tank 1b, the heat exchange part 36 of the heat medium pipe 34 of the heating apparatus 10 provided in the one reaction tank 1a is arranged. Therefore, in the heat exchanger 33, heat exchange is performed between the mixed gas of the monomer and / or oligomer and fluid 3 that has come out of the reaction tank 1 b and the heat exchange unit 36, and the heat medium in the heat medium pipe 34. Is heated by this gas mixture. And the latent heat at the time of the liquefaction of the monomer and / or oligomer in the mixed gas is recovered in the heat medium. In this way, the heat when the monomer and / or oligomer in the mixed gas is cooled and liquefied can be recovered by the heat medium in the heat medium pipe 34. In addition, when the heating medium is heated by the heater 35 to raise the temperature in the reaction tank 1a to a temperature suitable for the decomposition reaction of the thermosetting resin 2, the amount of heat generated by the heater 35 can be reduced, and the energy efficiency is improved. Driving. In the embodiment of FIG. 9, heat is recovered from the mixed gas of the monomer and / or oligomer and fluid 3 that exits from the reaction tank 1 b out of the reaction tanks 1 a and 1 b. Similarly, by using the heat exchanger 33 instead of the cooling device 14 in the reaction tank 1a, heat can be recovered from the mixed gas of the monomer and / or oligomer and the fluid 3 exiting the reaction tank 1a.

  FIG. 10 shows another example of the embodiment of the present invention. A fluid storage tank 40 is connected to the upper part of the reaction tank 1 by a supply pipe 41. One end of the fluid return pipe 17 is connected to the bottom of the fluid recovery container 22, and the other end is connected to the fluid storage tank 40. The recovery pipe 13 is connected to the reaction tank 1, the recovery container 15 and the fluid recovery container 22, the fluid return pipe 17 is connected to the fluid recovery container 22 and the fluid storage tank 40, and the supply pipe 41 of the fluid storage tank 40 is connected to the reaction tank 1. Connected. Accordingly, a sealed system is formed that can maintain the high pressure in the reaction tank 1 even when the on-off valve 8 of the recovery port 6 is kept open. The supply pipe 41 is provided with a liquid feeding pump 42. An alkali salt storage tank 43 is connected to the upper part of the fluid storage tank 40 by a supply pipe 44. The fluid storage tank 40 mixes and stores the fluid 3 and the alkali salt. In addition, the reaction tank 1 is provided with a pH sensor 45 that measures the pH of the fluid 3 in the reaction tank 1, and a pH controller 46 that receives the signal from the pH sensor 45 and sends a signal to the pump 42 to control the pump 42. ing. According to the pH of the fluid 3 in the reaction tank 1 measured by the pH sensor 45, the pH controller 46 operates the pump 42 to react the mixed liquid of the fluid 3 and the alkali salt stored in the fluid storage tank 40. Feed into tank 1. Other configurations are the same as those of the apparatus shown in FIG.

  According to the apparatus of FIG. 10, as in FIGS. 3 to 7, thermosetting is performed in the reaction tank 1 under high temperature and high pressure conditions in which the fluid 3 becomes a critical state with the on-off valve 8 of the recovery port 6 opened. The decomposition reaction of the functional resin 2 can be performed. In addition, the monomer and / or oligomer 4 in the gas can be liquefied and recovered in the recovery container 15 by cooling the gas coming out from the recovery port 6 of the reaction tank 1 to the recovery pipe 13 with the cooling device 14. . Further, by cooling the fluid 3 in the gas with the fluid cooling device 20, the fluid 3 can be liquefied and recovered in the fluid recovery container 22. The liquid fluid 3 in the fluid recovery container 22 is pressurized by the pump 23 and returned to the liquid storage tank 40 through the fluid return pipe 17. Thus, the alkali salt is mixed with the fluid 3 returned to the liquid storage tank 40. Further, the pH of the fluid 3 in the reaction tank 1 can be confirmed at any time by the pH sensor 45 provided in the reaction tank 1. When the pH of the fluid 3 becomes a predetermined value or lower, the pH controller 46 operates the pump 42 until the pH of the fluid 3 in the reaction tank 1 reaches a predetermined value, and the alkali salt in the liquid storage tank 40 is Can be supplied to the reaction tank 1 through the supply pipe 41. That is, the pH of the fluid in the reaction tank can be confirmed at any time, and an alkali salt can be supplied into the reaction tank at any time according to the pH. As a result, the pH of the fluid 3 in the reaction tank 1 can always be maintained at a predetermined value (for example, alkaline). Therefore, the thermosetting resin 2 can be efficiently decomposed over a long period of time, and the recovery rate of the monomer and / or oligomer 4 can be increased. Further, since the fluid excluding the monomer and / or oligomer can be circulated, the monomer and / or oligomer can be prevented from being further decomposed by the alkali salt.

FIG. 11 shows another example of the embodiment of the present invention. A liquid supply pipe 51 is connected to the lower part of the reaction tank 1, and a liquid supply pump 52 is provided in the liquid supply pipe 51. Other configurations are the same as those of the apparatus shown in FIG.
FIG. 12 shows another example of the embodiment of the present invention. The reaction tank 1 includes a flow rate sensor 53 that measures the amount of the fluid 3 in the reaction tank 1 and a controller 54 that receives the signal from the flow rate sensor 53 and sends a signal to the liquid supply pump 52 to control the liquid supply pump 52. Is provided. The controller 54 operates the liquid supply pump 52 according to the amount of fluid in the reaction tank 1 measured by the flow sensor 53, and sends the fluid 3 into the reaction tank 1 through the liquid supply pipe 51. Other configurations are the same as those of the apparatus shown in FIG.

11 and 12, as in the case of FIG. 2, after the thermosetting resin 2 is decomposed and reacted in the reaction tank 1 using the fluid 3 in a critical state, the monomer and / or oligomer 4 is liquefied. And can be collected in the collection container 15.
According to the apparatus of FIG. 11, the fluid 3 can be supplied from the liquid supply pipe 51 to the lower part of the reaction tank 1 by the liquid supply pump 52. For example, after completion of the decomposition of the thermosetting resin, when the open / close valve at the top of the reaction tank is opened to recover the vapor containing the monomer and / or oligomer, the fluid can be fed from the bottom of the reaction tank. As a result, the amount of fluid in the reaction vessel can be kept substantially constant.
Moreover, according to the apparatus of FIG. 12, the quantity of the fluid 3 in the reaction tank 1 can be confirmed at any time by the flow sensor 53 provided in the reaction tank 1. When the amount of fluid in the reaction tank 1 becomes a predetermined amount or less, the controller 54 operates the liquid supply pump 52 until the amount of fluid in the reaction tank 1 reaches the predetermined amount, and the reaction tank 1 The fluid 3 can be supplied to the lower part. That is, the amount of fluid in the reaction tank can be confirmed at any time, and fluid can be supplied into the reaction tank at any time according to the amount. As a result, the amount of fluid in the reaction vessel can always be kept substantially constant.
Therefore, according to the apparatus of FIG.11 and FIG.12, even if decomposition | disassembly of a thermosetting resin advances, the raise of the density | concentration of a decomposition liquid can be suppressed and it can prevent that a decomposition product adheres to an inner wall and burns. Furthermore, the inorganic substance precipitated in the lower part of the reaction tank can be washed to separate the adhering monomer and / or oligomer and dissolved in the fluid. Therefore, the yield of monomers and / or oligomers can be increased.

The invention is further illustrated by the following examples.
In Examples, the glycol recovery rate, the organic acid recovery rate, and the production rate of a compound containing an acid residue derived from a polyester and a residue derived from a cross-linked portion (hereinafter also referred to as “compound [1]”) are as follows. I asked for it.
[Glycol recovery rate]
The glycol recovery rate was calculated from the following formula.
Glycol recovery rate (%) = quantitative result of glycol monomer component / estimated content of glycol monomer component of thermosetting resin × 100
[Organic acid recovery rate]
The organic acid recovery rate was calculated from the following equation.
Organic acid recovery rate (%) = quantification result of organic acid monomer component / estimated content of organic acid monomer component of thermosetting resin × 100
[Production Rate of Compound (Compound [1]) Containing Polyester-Derived Acid Residue and Cross-Linked Section Residue]
The production rate of compound [1] was calculated from the following formula.
Production rate (%) of compound [1] = (dry weight of precipitate formed by adding hydrochloric acid to water-soluble component after decomposition treatment to adjust pH to about 4) / (compound obtained by decomposition) The estimated content of compound [1] determined from the ratio of the number of molecules of the acid residue and the residue derived from the crosslinking portion obtained by NMR and the amount of the crosslinking portion-forming material used) × 100

(Example)
A test thermosetting resin (unsaturated polyester resin) was prepared. First, a varnish containing 65 wt% of a polyhydric alcohol glycol, 10 wt% of neopentyl glycol, 25 wt% of dipropylene glycol, and maleic anhydride, an unsaturated organic acid, in an amount equivalent to the total amount of glycol is cross-linked. As an agent, styrene was blended in an equivalent amount to the varnish. Then, the said thermosetting resin was obtained by mix | blending 165 mass parts of calcium carbonate and 90 mass parts of glass fiber with 100 mass parts of mixtures of a varnish and styrene.
40 kg of the above thermosetting resin and 160 kg of a NaOH aqueous solution having a concentration of 0.72 mol / L were put into the reaction tank of FIG. Thereafter, the temperature of the reaction tank charged with the thermosetting resin and the aqueous NaOH solution was raised to 230 ° C., the water in the reaction tank was brought into a subcritical state, and the thermosetting resin was decomposed for 4 hours. After turning off the heating device, the steam containing the monomer and / or oligomer was extracted through the recovery pipe by opening the recovery port on-off valve for 1 hour while maintaining at about 230 ° C. The steam was allowed to flow through a heat exchanger cooled by passing through room temperature tap water and allowed to flow into the recovery container while cooling, thereby recovering the fluid containing the monomer and / or oligomer.
The glycol monomer component in the water-soluble component of the recovered fluid was quantified by gas chromatography analysis (GC analysis), and the glycol recovery rate was calculated. The organic acid monomer component was quantified by ion exchange chromatography analysis (IC analysis) to calculate the organic acid recovery rate.
Next, the water-soluble component is acidified with hydrochloric acid, and the resulting precipitate is separated and recovered with an organic solvent, and the mass is measured. By comparison and calculation with the mass of the thermosetting resin, the acid residue derived from the polyester and The production rate of the compound containing the residue derived from the cross-linked portion (compound [1] in the table) was calculated. The results are shown in Table 1.

  As is apparent from Table 1, the vapor containing monomer and / or oligomer is recovered by opening the opening / closing valve of the recovery port while maintaining the temperature in the reaction vessel at the temperature at which the monomer and / or oligomer evaporates after the reaction is completed. Further, it was confirmed that monomers and / or oligomers can be recovered therefrom. In particular, it was possible to efficiently recover the fluid containing glycol that hardly contained the organic acid and the compound [1] into the collection container.

Claims (8)

Decomposing a thermosetting resin obtained by crosslinking a copolymer of a polyhydric alcohol and an acid with a crosslinking agent into monomers and / or oligomers using a supercritical or subcritical fluid in a reaction vessel;
Generating a gas containing the monomer and / or oligomer by maintaining the reaction liquid in the reaction vessel at a temperature at which the monomer and / or oligomer evaporates;
And recovering the monomer and / or oligomer by recovering the gas;
A method for decomposing a thermosetting resin.   By cooling the recovered gas to a temperature lower than the boiling point of the monomer and / or oligomer and higher than the boiling point of the fluid, the monomer and / or oligomer contained in the gas and the fluid are separated. The method of claim 1, comprising recovering the monomer and / or oligomer.   The method according to claim 2, comprising liquefying the fluid separated from the monomer and / or oligomer and decomposing the thermosetting resin in the reaction vessel while returning the liquefied fluid to the reaction vessel.   The method according to claim 3, comprising mixing a new thermosetting resin with the liquefied fluid and decomposing the thermosetting resin in the reaction vessel while supplying the mixture to the reaction vessel.   The method according to claim 1, comprising separating the monomer and / or oligomer contained in the collected gas from the fluid by an adsorption unit or a membrane separation unit and collecting the monomer and / or oligomer.   The method according to claim 1, comprising decomposing the thermosetting resin in the reaction vessel while supplying an alkali salt to the reaction vessel.   The method according to claim 3, comprising mixing an alkali salt with the liquefied fluid and decomposing the thermosetting resin in the reaction vessel while supplying the mixture to the reaction vessel. The method according to any one of claims 1 to 7, comprising decomposing the thermosetting resin in the reaction vessel while supplying a fluid to the reaction vessel.

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