KR102530557B1 - Method and apparatus for decomposing and recycling thermosetting resin composite material, and composition used therein - Google Patents

Abstract

pretreating the thermosetting resin composite material in an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and a step of putting the pretreated thermosetting resin composite material into a hydrogen peroxide solution or an aqueous formic acid solution and performing a main treatment thereon, wherein the aqueous solution used for the pretreatment and main treatment are different from each other. And devices, compositions and kits utilized therein are disclosed. According to this, unlike the conventional chemical decomposition method, the decomposition reaction time can be significantly shortened even under low temperature and normal pressure conditions, and it is possible to improve the difficulty of building mass production facilities due to the odor (smell) of chemical solutions and corrosion of materials. In addition, since the reaction performance can be maintained despite lowering the concentration of the chemical solution, the number of times of use of the solution can be greatly increased. Accordingly, the production cost can be drastically reduced.

Description

Method and apparatus for decomposing and recycling thermosetting resin composite material, and composition used therein}

The present specification relates to a thermosetting resin composite material decomposition and recycling method and apparatus, and an aqueous solution composition utilized therein. Specifically, a method and apparatus for disassembling and recycling thermosetting resin composite materials, which can effectively decompose and recycle composite materials in which carbon fibers are impregnated and cured with thermosetting resin using an eco-friendly aqueous solution-based chemical reaction, and an aqueous solution used therein It's about the composition.

Thermosetting resins are widely used in composite materials such as, for example, carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP). The use of these composite materials is gradually increasing in all fields of industry, such as the automobile, aerospace, and new energy fields. and the need for recycling is growing.

However, due to its characteristics, once cured, thermosetting resins are not easily soluble in solvents unless heat is applied, making them difficult to recycle. Representative resins of thermosetting resins include polyurethane and epoxy resins.

Conventionally, as a method of processing such a thermosetting resin composite material, thermal decomposition and chemical decomposition methods are largely used.

The pyrolysis method has been used or is still being used by Japanese companies such as Toray and Teijin, or companies such as Adherent Technology (USA), Procotex (France), and ELG Carbon Fiber (UK). However, the pyrolysis process requires a high temperature of 500 ° C. or more, and is not environmentally friendly, such as the production of harmful substances to the human body, so the use of the pyrolysis process is gradually decreasing.

Meanwhile, as a chemical decomposition method, a method based on an organic solvent or a method of processing under special process conditions such as a supercritical or semicritical process is used.

However, there is still a problem that the organic solvent-based method is also not environmentally friendly. In addition, such an organic solvent-based treatment solution itself has a problem in that an expensive solution (eg, benzyl alcohol, etc.) is used or reuse is often limited, resulting in increased production cost.

In addition, since the process is performed under high pressure in the case of supercritical conditions, there is a disadvantage in that it is not economical due to the possibility of exposure to hazards during work and the increase in cost for equipping and maintaining safety facilities and devices.

In recent years, techniques for excluding organic solvents as much as possible and treating water under mild conditions have been developed (Patent Document 1).

However, in the case of the chemical method, the actual decomposition efficiency is not high, so the treatment time is long, and it cannot be practically used in a large-scale treatment process other than a laboratory level.

In addition, even under mild conditions, there is a problem in that handling of the chemical solution to be used is very difficult, so there is a limit to the application in the actual field. For example, the smell (odor) of the chemical solution itself is strong, making it difficult to work, and in the case of installing production equipment and proceeding with the process, there has been a problem of complaints from neighboring companies despite having facilities such as dust collectors and scrubbers. However, these practical problems are becoming obstacles to the application of the technology.

In addition, in configuring various facilities such as reactors, pumps, pipes, valves, etc., or instrumentation and control equipment, expensive materials (eg, titanium, etc.) are used to prepare for corrosiveness, or the equipment or instrumentation and control equipment There is a problem that requires frequent replacement.

Therefore, the present inventors are an aqueous solution-based decomposition method excluding organic solvents, which can be decomposed under mild conditions and has high decomposition efficiency, so it can be applied to large-scale treatment facilities. Decomposition and recycling technology of thermosetting resin composite materials, which have no problems and require less replacement of related equipment, have been intensively studied to arrive at the present invention.

Korean Patent No. 1861095

In exemplary embodiments of the present invention, in one aspect, an aqueous solution-based decomposition method that does not use an organic solvent is capable of decomposition under mild conditions of low temperature and atmospheric pressure and has high decomposition efficiency, so that it can be applied to large-scale treatment facilities. It is to provide a resin composite material decomposition and recycling method and apparatus, a composition utilized therein, and a kit including the same.

In exemplary embodiments of the present invention, on the other hand, the handling and corrosion problems can be significantly improved, and the chemical reaction rate is greatly increased compared to the prior art, which can improve productivity, decomposition of thermosetting resin composites. And to provide a recycling method and device, a composition utilized therein, and a kit including the same.

In exemplary embodiments of the present invention, in another aspect, the reusability of the aqueous solution used for the decomposition treatment of the thermosetting resin composite material is excellent, and the performance of the treatment process and the control of treatment conditions are easy, decomposition of the thermosetting resin composite material And to provide a recycling method and device, a composition utilized therein, and a kit including the same.

In exemplary embodiments of the present invention, pre-treating the thermosetting resin composite material in an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and adding the pretreated thermosetting resin composite material to a hydrogen peroxide solution or an aqueous formic acid solution and performing a main treatment thereon, wherein the aqueous solutions used for the pretreatment and main treatment are different from each other, providing a method for decomposing the thermosetting resin composite material. do.

Further, in exemplary embodiments of the present invention, a pre-impregnation bath for pre-impregnating the thermosetting resin composite material in a formic acid solution or an aqueous hydrogen peroxide solution; a pretreatment tank connected to the pre-impregnation tank to which the thermosetting resin composite material obtained from the pre-impregnation tank is transported and carrying an aqueous solution of formic acid or an aqueous solution of hydrogen peroxide; and a main treatment tank connected to the pretreatment tank, to which the thermosetting resin composite material obtained in the pretreatment tank is transported, and carrying an aqueous solution of hydrogen peroxide or an aqueous solution of formic acid, wherein the aqueous solutions loaded in the pretreatment tank and the main treatment tank are different from each other, An apparatus for decomposing a thermosetting resin composite material is provided.

Further, in exemplary embodiments of the present invention, as a decomposition kit for a thermosetting resin composite material, a pre-impregnation composition including a formic acid solution or a hydrogen peroxide solution; a pretreatment composition comprising an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and a main treatment composition comprising an aqueous solution of hydrogen peroxide or an aqueous solution of formic acid, wherein the pretreatment composition and the aqueous solution of the main treatment composition are different from each other, and a thermosetting resin composite material decomposition kit is provided.

In addition, exemplary embodiments of the present invention provide a decomposition composition for a thermosetting resin composite material in which a radical initiator is added in an amount of 0.1 to 2 wt% or less in an aqueous hydrogen peroxide solution or an aqueous formic acid solution, preferably in an aqueous hydrogen peroxide solution.

According to exemplary embodiments of the present invention, unlike conventional chemical decomposition methods, the decomposition reaction time can be remarkably shortened even under mild conditions of low temperature and normal pressure, and odor of chemical solutions and corrosion of materials, etc. It is possible to improve the difficulty of building mass production facilities due to this, and to maintain reaction performance despite lowering the concentration of the chemical solution, so that the number of times of use of the solution can be greatly increased. In addition, the reusability of the aqueous solution used for the decomposition treatment of the thermosetting resin composite material is excellent, and it is easy to perform the treatment process and control the treatment conditions. According to the above, the production cost can be drastically lowered.

1 is a table of results showing the corrosiveness of an alternative solution used in an exemplary embodiment of the present invention versus the corrosiveness of an existing solution.
Figure 2 is a result picture showing the reaction rate improvement when using an alternative solution in this experiment 1.
3a to 3g are photographs of CFRP before and after disassembly in Experiment 2.
4a to 4h are CFRP photographs before and after disassembly in Experiment 3.
5 is a result showing the reduction of the decomposition time according to the pre-impregnation in Experiment 4.
Figure 6 is a graph showing the concentration and pH change according to the heating (90 ℃) time when a buffer solution is added or not added in the case of a solution (solution D) used in an exemplary embodiment of the present invention.
7 shows the results of repeated decomposition (heating temperature 90 ° C., reaction time per reaction time of about 5 hours per time) by adding a buffer solution to adjust the concentration in the case of a solution (solution D) used in an exemplary embodiment of the present invention. It is a graph that represents

term definition

In the present specification, the thermosetting resin composite material refers to various composite materials including a thermosetting resin. For example, the epoxy resin composite material may include a cured epoxy resin material and various fillers such as carbon fibers.

Recycling in this specification means including a process of chemically treating and decomposing the thermosetting resin composite material.

The term decomposition used in this specification and particularly in the claims may mean disassembly and subsequent recycling (recycling) together in addition to decomposition itself.

In this specification, disassembly and recycling are defined as meaning including one or more of the disassembly and recycling processes.

In this specification, pre-impregnation means impregnating for a certain period of time under normal pressure and at room temperature, which cannot be seen as substantial heat treatment. Here, the temperature that cannot be regarded as substantial heat treatment may be room temperature without any heating or 40° C. or less, which is a temperature that cannot be regarded as substantial heat treatment, but is preferably room temperature. The thermosetting resin composite material is supported in an aqueous solution such as an aqueous solution of formic acid or an aqueous solution of hydrogen peroxide at such temperature and normal pressure for a certain period of time.

In the present specification, pretreatment refers to supporting the thermosetting resin composite material in an aqueous solution such as an aqueous solution of formic acid or an aqueous solution of hydrogen peroxide at normal pressure and a temperature of 80 ° C to 120 ° C, preferably heated to less than 100 ° C, which is the boiling point of water, for a certain period of time.

In the present specification, the treatment refers to holding the thermosetting resin composite material subjected to the pretreatment in an aqueous solution such as an aqueous solution of formic acid or an aqueous solution of hydrogen peroxide at a temperature heated to normal pressure and 80 ° C to 120 ° C, preferably less than 100 ° C, which is the boiling point of water, for a certain period of time means that

Solution A in this specification refers to an aqueous solution of acetic acid.

Solution B in this specification refers to an aqueous solution of sodium hypochlorite.

In this specification, C solution refers to an aqueous solution of formic acid.

In this specification, D solution refers to an aqueous hydrogen peroxide solution.

In the present specification, the radical initiator is a material capable of generating radical species and promoting a radical reaction under mild conditions, and formic acid used during the process of pre-impregnation, pre-treatment, and/or main treatment in exemplary embodiments of the present invention. It means further added to an aqueous solution and/or an aqueous hydrogen peroxide solution.

In the present specification, aqueous solution reusability refers to the property that the aqueous solution used in each process of pre-impregnation, pre-treatment, and main treatment can be reused in the same process.

In this specification, the concentration is expressed as a percentage of the weight of the substance to be added out of the total mass of the solution.

Description of Exemplary Embodiments

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

The present inventors have recognized the harsh process conditions of the conventional chemical decomposition method of thermosetting resin composite materials, the problem of chemical solution handling, the problem of corrosiveness and the increase in the cost of chemical solutions, and as a result of intensive research to continuously improve them, the present invention reached

In detail, when the carbon fiber composite material is chemically recycled as the most recently used method, for example, pretreatment is performed with an aqueous solution of acetic acid, followed by sequential treatment with an aqueous solution containing sodium hypochlorite to decompose the thermosetting resin, and then into the solution. A method of recovering the remaining carbon fibers was used, but this method had considerable problems in practical application.

In other words, the above method has serious limitations in handling the solution and equipping the reaction equipment due to the strong corrosiveness and odor of acetic acid (to be precise, glacial acetic acid) itself. Even alloys such as SUS316 with rapid corrosion have caused many difficulties in equipping reaction equipment.

Therefore, in the exemplary embodiments of the present invention, in order to obtain high decomposition efficiency while improving the above-described problems such as handling and corrosiveness, stepwise decomposition of pretreatment and main treatment is performed while employing alternative solutions (formic acid aqueous solution and hydrogen peroxide aqueous solution) In addition, a pre-impregnation process is performed before pre-treatment.

For example, the pretreatment is performed with an aqueous formic acid solution or an aqueous hydrogen peroxide solution instead of acetic acid, and the main treatment is performed using an aqueous solution of hydrogen peroxide or an aqueous formic acid solution instead of sodium hypochlorite. From the viewpoint of reusability, mass productivity, handling such as reaction control, and decomposition efficiency, each aqueous solution used in the pretreatment and main treatment is configured to be different from each other.

Accordingly, handling and corrosiveness are drastically improved, and, as will be described later, the chemical reaction rate is significantly increased compared to the conventional method, thereby increasing the decomposition rate and consequently improving productivity. In addition, as reusability is high, mass productivity capable of large-scale processing can be improved.

1 is a table of results showing the corrosiveness of an alternative solution used in an exemplary embodiment of the present invention versus the corrosiveness of an existing solution.

As shown in FIG. 1, although acetic acid or sodium hypochlorite, which are existing solutions, have corrosion problems as the number of reactions increases, both SUS 304 and SUS 316 alloys, in the case of formic acid and hydrogen peroxide used in exemplary embodiments of the present invention It is good without corrosion problems, and the reaction temperature can be treated more quickly at less than 100 ℃, which is the boiling point of water.

In an exemplary embodiment of the present invention, the pretreatment solution (C solution: formic acid aqueous solution) and the solution used for the main treatment (D solution: aqueous hydrogen peroxide solution) were combined with the existing pretreatment solution (A solution: acetic acid aqueous solution) and the solution used for the main treatment. (B solution: sodium hypochlorite aqueous solution), the overall performance and cost are compared and shown in the following corrosiveness result table.

processing alloy Pretreatment main processing A solution C solution B solution D solution SUS 304 alloy damage No alloy damage alloy damage No alloy damage Stainless Steel 316 alloy surface damage No alloy damage alloy damage No alloy damage

As described above, in exemplary embodiments of the present invention, when the alternative solutions (formic acid aqueous solution and hydrogen peroxide aqueous solution) are used, as the corrosiveness is reduced compared to the conventional ones, it is easy to select materials constituting the reaction equipment, and as described later, the decomposition efficiency Even thermosetting resin composite materials, which are excellent and difficult to disassemble, can be easily disassembled.

On the other hand, in an exemplary embodiment, the pretreatment and main treatment reaction times may be further shortened by pre-impregnating the composite material in an aqueous formic acid solution or an aqueous hydrogen peroxide solution (within about 10 hours) before introducing the composite material into the decomposition reaction.

Specifically, in exemplary embodiments of the present invention, a method for recycling a thermosetting resin composite material may include pretreating the thermosetting resin composite material in a formic acid solution or a hydrogen peroxide solution; and putting the pretreated thermosetting resin composite material into a hydrogen peroxide solution or a formic acid solution and performing a main treatment. As described above, the pretreatment solution and the present treatment solution use different solutions.

In an exemplary embodiment, the pre-impregnation is 17 hours or less, preferably 10 hours or less, at room temperature and normal pressure, depending on the type of thermosetting resin composite material to be decomposed. For example, it may be performed in more than 0 hours, less than 10 hours, 1 to 9 hours, 2 to 8 hours, 3 to 7 hours, and 4 to 6 hours. In non-limiting examples, pre-impregnation is carried out at room temperature and pressure for 10 hours or less, 9 hours or less, 8 hours or less, 7 hours or less, 6 hours or less, 5 hours or less, 4 hours or less, 3 hours or less, 2 hours or less, 1 Can be done in less than an hour. Further, the pre-impregnation may be performed for more than 0 hours, more than 1 hour, more than 2 hours, more than 3 hours, more than 4 hours, more than 5 hours, more than 6 hours, more than 7 hours, more than 8 hours, more than 9 hours.

In an exemplary embodiment, the pretreatment may be performed at normal pressure and 80 to 120 ° C, preferably 80 to less than 100 ° C, 85 to 95 ° C, or 90 ° C for 1 to 6 hours.

In non-limiting examples, the pretreatment temperature may be 80 ° C or higher, 85 ° C or higher, 90 ° C or higher, 95 ° C or higher, and 120 ° C or lower, 115 ° C or lower, 110 ° C or lower, 105 ° C or lower, preferably lower than 100 ° C. , 95 ° C or less, 90 ° C or less, may be 85 ° C or less.

In non-limiting examples, the pretreatment time may be 1 hour or more, 1.5 hours or more, 2 hours or more, 2.5 hours or more, 3 hours or more, 3.5 hours or more, 4 hours or more, 4.5 hours or more, 5 hours or more, 5.5 hours or more. 6 hours or less, 5.5 hours or less, 5 hours or less, 4.5 hours or less, 4 hours or less, 3.5 hours or less, 3 hours or less, 2.5 hours or less, 2 hours or less, or 1.5 hours or less.

In an exemplary embodiment, the main treatment may be performed at normal pressure and 80 to 120 ° C, preferably 80 to less than 100 ° C, 85 to 95 ° C, or 90 ° C for 1 to 3 hours.

In non-limiting examples, the main treatment temperature may be 80 ° C or higher, 85 ° C or higher, 90 ° C or higher, 95 ° C or higher, and 120 ° C or lower, 115 ° C or lower, 110 ° C or lower, 105 ° C or lower, preferably 100 ° C. It may be less than, 95 ℃ or less, 90 ℃ or less, 85 ℃ or less.

In non-limiting examples, the main treatment time may be 1 hour or more, 1.5 hours or more, 2 hours or more, 2.5 hours or more, 3 hours or less, 2.5 hours or less, 2 hours or less, or 1.5 hours or less.

In an exemplary embodiment, the concentration of formic acid in the aqueous solution of formic acid may be 50% or more and less than 100%, but from an environmental point of view, it is preferably 90% or less, or less than 85%, and from the viewpoint of reactivity, 50% or more is used.

In a non-limiting example, the formic acid concentration may be, for example, 50-90%. For example, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or more, 55% or more, 60% or more, 65% It may be 70% or more, 75% or more, 80% or more, or 85% or more.

In an exemplary embodiment, the hydrogen peroxide concentration in the hydrogen peroxide aqueous solution may be 20% or more and 50% or less, but from an environmental point of view, it is preferably used at less than 35%, and from the viewpoint of reactivity, it is used at 30% or more. Above 50% there is a risk of explosion.

In non-limiting examples, hydrogen peroxide concentrations of 34.5% or less, 34% or less, 33.5% or less, 33% or less, 32.5% or less, 32% or less, 31.5% or less, 31% or less, 30.5% or less may be used.

In non-limiting examples, hydrogen peroxide concentrations of 30% or more, 30.5% or more, 31% or more, 31.5% or more, 32% or more, 32.5% or more, 33% or more, 33.5% or more, 34% or more can be used.

On the other hand, as can be seen in the experimental examples described later, in the aqueous solution-based decomposition, it was confirmed that using a specific solution in a specific sequence during pre-impregnation, pre-treatment, and main treatment resulted in a large difference in actual degradation efficiency. Although the reason has not been clarified, it is thought that the type of chemical substance used in each process of pre-impregnation, pre-treatment and main treatment in the case of aqueous solution affects the decomposition mechanism and efficiency.

In addition, the reaction can proceed more efficiently by changing the treatment order of the formic acid aqueous solution and the hydrogen peroxide aqueous solution according to the type of thermosetting resin composite material to be decomposed and recycled.

For example, in cases where decomposition is very difficult, such as CFRP constituting an aircraft body, it is preferable to use a decomposition sequence with a relatively high efficiency in addition to the addition of a radical initiator described later.

On the other hand, when a small amount of a radical initiator is used in at least one of the above-described pre-impregnation, pre-treatment, and main treatment, in particular, at least one of the pre-treatment and main treatment, the decomposition efficiency can be dramatically increased, for example, to 10% or more. Considering that it is difficult to increase only the decomposition efficiency while fixing other conditions in the chemical decomposition process of thermosetting resin composite materials, it is surprising that the decomposition efficiency can be increased by about 10% only by adding a small amount of a radical initiator.

Although the mechanism has not been clearly identified, the radical initiator in the process of pre-impregnation, pre-treatment and/or main treatment using solution C and/or solution D is thought to increase the decomposition efficiency by participating in the radical reaction during the decomposition of thermosetting resin composites. .

In an exemplary embodiment, the radical initiator is preferably an azo compound or an organic peroxide from the viewpoint of increasing decomposition efficiency.

As a non-limiting example, an azo compound that is a radical initiator may be azobisisobutyrnitrile (AIBN).

As a non-limiting example, the organic peroxide as a radical initiator may be benzoyl peroxide (BPO), acetyl peroxide, dilauryl peroxide, or the like.

In an exemplary embodiment, the radical initiator in the formic acid aqueous solution or hydrogen peroxide aqueous solution is preferably added in an amount of 0.01 to 2 wt% from the viewpoint of decomposition efficiency . When used in excess of 2 wt%, a problem in controlling a chemical reaction may occur due to excessive reactivity.

In an exemplary embodiment, the decomposition sequence of the method for decomposing the thermosetting resin composite material may include pre-impregnating the thermosetting resin composite material in an aqueous solution of formic acid; pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution to which a radical initiator is added; and putting the pretreated thermosetting resin composite material into an aqueous solution of formic acid and performing main treatment.

In an exemplary embodiment, the decomposition sequence of the method for decomposing the thermosetting resin composite material may include pre-impregnating the thermosetting resin composite material in an aqueous solution of formic acid; pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution; and putting the pretreated thermosetting resin composite material into an aqueous solution of formic acid to which a radical initiator is added and performing a main treatment.

In an exemplary embodiment, the decomposition sequence of the method of decomposing the thermosetting resin composite material may include pre-impregnating the thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution to which a radical initiator is added; and putting the pretreated thermosetting resin composite material into an aqueous solution of formic acid and performing main treatment.

In an exemplary embodiment, the decomposition sequence of the method of decomposing the thermosetting resin composite material may include pre-impregnating the thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution; and putting the pretreated thermosetting resin composite material into an aqueous solution of formic acid to which a radical initiator is added and performing a main treatment.

In an exemplary embodiment, the decomposition sequence of the method of decomposing the thermosetting resin composite material may include pre-impregnating the thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material in an aqueous solution of formic acid to which a radical initiator is added; and putting the pretreated thermosetting resin composite material into an aqueous hydrogen peroxide solution and performing main treatment.

In an exemplary embodiment, the decomposition sequence of the method of decomposing the thermosetting resin composite material may include pre-impregnating the thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material in an aqueous solution of formic acid; and putting the pretreated thermosetting resin composite material into an aqueous hydrogen peroxide solution to which a radical initiator is added and performing main treatment.

On the other hand, in one exemplary embodiment, the concentration and / or pH of the aqueous hydrogen peroxide solution can be adjusted to maintain within a certain range in order to maintain the continuous decomposition characteristics, and a buffer solution for adjusting the concentration and / or pH can be used. there is.

In a non-limiting example, as the reaction using the hydrogen peroxide aqueous solution during the pretreatment or main treatment proceeds, the concentration and pH fluctuate while having a similar correlation, and a buffer solution may be used to compensate for this and maintain continuous decomposition characteristics. . At this time, one or more of citric acid, tartaric acid, and phosphoric acid may be used as the buffer solution.

In a non-limiting example, the concentration of the hydrogen peroxide aqueous solution is preferably less than 35% compared to before the decomposition treatment, but 30% or more.

In exemplary embodiments, the decomposition rate in the decomposition method of the thermosetting resin composite material can be measured by thermogravimetric analysis (TGA), which can confirm the decomposition rate of organic matter, and the decomposition rate by thermogravimetric analysis is 90%. 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, particularly preferably 98% or more, 99% or more, most preferably 100%

The decomposition rate is considered to be close to 100% as the organic/inorganic residue is closer to 0% by TGA analysis of the finally recovered (after drying) carbon fiber (reclaimed carbon fiber).

Meanwhile, an apparatus for decomposing a thermosetting resin composite material according to exemplary embodiments of the present invention may include a pretreatment unit (or a pretreatment region) for pretreating the thermosetting resin composite material in a formic acid solution or a hydrogen peroxide solution; and a main treatment unit (or main treatment area) for putting the pretreated thermosetting resin composite material into a hydrogen peroxide solution or a formic acid solution and performing the main treatment. The pretreatment solution and the present treatment solution are composed of different solutions.

In an exemplary embodiment, the apparatus may further include a pre-impregnation unit (or pre-impregnation area) for pre-impregnating the thermosetting resin composite material in a formic acid solution or a hydrogen peroxide solution before pre-treatment.

Further, in an exemplary embodiment, the thermosetting resin composite material decomposition device includes a pre-impregnation bath for pre-impregnating the thermosetting resin composite material in a formic acid solution or an aqueous hydrogen peroxide solution; a pretreatment tank connected to the pre-impregnation tank by, for example, a conveyor belt, transporting the thermosetting resin composite material obtained from the pre-impregnation tank, and supporting an aqueous solution of formic acid or an aqueous solution of hydrogen peroxide; and a main treatment tank connected to the pretreatment tank by, for example, a conveyor belt, transporting the thermosetting resin composite material obtained in the pretreatment tank, and supporting an aqueous solution of hydrogen peroxide or an aqueous solution of formic acid.

Meanwhile, in exemplary embodiments of the present invention, a decomposition kit for a thermosetting resin composite material may be provided.

The kit includes a pre-impregnation composition comprising a formic acid solution or a hydrogen peroxide solution; a pretreatment composition comprising an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and a main treatment composition comprising an aqueous solution of hydrogen peroxide or an aqueous solution of formic acid. The aqueous solutions of the pre-treatment composition and the main treatment composition are configured to be different from each other.

In an exemplary embodiment, the kit may further include a radical initiator in an aqueous hydrogen peroxide solution or an aqueous formic acid solution, particularly preferably in an aqueous hydrogen peroxide solution. Here, it is preferable that the radical initiator is added in an amount of 0.01 to 2 wt% or less in the aqueous hydrogen peroxide solution or the aqueous formic acid solution.

Hereinafter, specific embodiments according to exemplary implementations of the present invention will be described in more detail. However, the present invention is not limited to the following examples, and various types of examples can be implemented within the scope of the appended claims, and only the following examples will complete the disclosure of the present invention and at the same time, common in the art. It will be understood that the intention is to facilitate practice of the invention to those skilled in the art.

[Experiment 1]

In this experiment 1, we examined whether the degradation efficiency was improved when using C solution and D solution, which are alternative solutions compared to the existing A and B solutions.

First, aircraft CFRP scrap (shredded product) was used as a raw material before disassembly. For reference, a photograph of CFRP scrap before disassembly is shown in FIG. 2 .

As solutions used for decomposition, an aqueous solution of glacial acetic acid (solution A - 99.9%) and an aqueous solution of sodium hypochlorite (solution B - 12%) were used, respectively. In addition, an aqueous solution of formic acid (solution C - 80%) and an aqueous solution of hydrogen peroxide (solution D - 34.5%) were used, respectively. Each A solution, B solution, C solution, and D solution were used in a ratio of 1:20 in volume ratio with respect to CFRP.

For reference, the volume ratio of the solution to the treated composite material in the pre-impregnation, pre-treatment and main treatment is 1 (composite material volume): 10 (solution volume) or more such as 1 (composite material volume): 10 (solution volume) to 1 ( Composite material volume): 30 (solution volume), but in terms of cost reduction, it is preferable that the solution volume ratio be as low as possible.

Figure 2 is a result picture showing the reaction rate improvement when using an alternative solution in this experiment 1. Figure 2a is the case of the existing solution, Figure 2b is the case of the present embodiment.

As shown in FIG. 2, in the case of the above-described existing solution, it is difficult to remove reaction residues even if the sum of the reaction times of the pretreatment (Step-1) and the main treatment (Step-2) exceeds 10 hours (see FIG. 2a). , In exemplary embodiments of the present invention, the reaction residues could be easily removed in a total of 4 hours for the total reaction time of the pretreatment (Step-1) and the main treatment (Step-2) (see FIG. 2b).

[Experiment 2]

In Experiment 2, the decomposition efficiency in the case of changing the decomposition sequence of pre-impregnation based on the sequence of using pre-treatment C solution and main treatment D solution, changing the time of pre-treatment and main treatment, and additionally using a radical initiator Changes were measured.

First, a CFRP plate for aircraft was used as a raw material before disassembly. The size was 30 x 30 x 5 mm (1 g). For reference, Figure 3a is a photograph of the CFRP plate before disassembly.

As solutions used for decomposition, formic acid aqueous solution (C solution - 80%) and hydrogen peroxide aqueous solution (D solution - 34.5%) were used, respectively. Each C solution and D solution were used in a ratio of 1:20 by volume to CFRP.

When performing dead point impregnation, 17 hours were performed at room temperature and pressure, and both pretreatment and main treatment were performed at normal pressure and 90 ° C.

As a radical initiator, 1 wt% of AIBN was used for each aqueous solution.

Decomposition efficiency was measured by thermal decomposition analysis (TGA). For reference, in the TGA analysis, SCINCO TGA N-1000 was used as the analyzer, the temperature range was RT ~ 800 ℃, the furnace was EGA, the heating speed was 10 ℃, and the N₂ atmosphere was used. The TGA analysis method is the same in these experiments.

The sequence, whether or not a radical initiator was added, and the decomposition rate of each Example of Experiment 2 are as follows. In each sequence, all other conditions except those indicated below were the same. On the other hand, photos after disassembly of Examples 1 to 6 are shown in FIGS. 3B to 3G, respectively.

Example pre-impregnated Pretreatment
(hour) main processing
(hour) decomposition rate
(TGA, %) note One D C(3) D(1) 90.3 Pre-impregnated +
basic conditions 2 doesn't exist C(3) D(1) 80.1 basic conditions 3 D C(4) D(2) 100.0 Comparison according to process time change compared to Example 1 4 doesn't exist C(4) D(2) 81.8 Comparison according to process time change compared to Example 2 5 D C(3)+
initiator D(1) 92.0 Compared to Example 1
Comparison according to addition of radical initiator to pretreatment process 6 D C(3) D(1)+
initiator 100.0 Comparison according to the addition of the radical initiator compared to Example 1 in the main treatment process

As can be seen from the above, in contrast to Examples 1 and 2, it can be seen that the decomposition efficiency is improved by about 10% when the other roughness is the same and pre-impregnation is further performed with the D solution.

In addition, comparing Examples 1 and 3, when the pretreatment time was increased by 1 hour and the main treatment time was increased by 1 hour, the decomposition efficiency reached 100% in the sequence D->C->D. However, when the pre-impregnation with D solution was not performed, the decomposition efficiency was low at 81.8% even though the pre-treatment time was increased by 1 hour and the main treatment time was increased by 1 hour. Therefore, even if the decomposition time is increased in the C solution pretreatment and the D solution main treatment sequence, it can be seen that there is a benefit according to the increase in the decomposition time when the pre-impregnation is performed with the D solution. For reference, since increasing the decomposition time is not desirable in terms of cost and efficiency of decomposition and recycling of the thermosetting resin composite material, it is necessary to achieve high decomposition efficiency while reducing the decomposition time as much as possible. From this point of view, the sequence of Example 6 described later shows very surprising results.

That is, in Example 5, compared to Example 1, a radical initiator was added to the pretreatment solution, and in this case, the decomposition efficiency increased by about 2%. On the other hand, in the case of Example 6, compared to Example 1, a radical initiator was added to the main treatment solution, and in this case, the decomposition efficiency rose dramatically to 100%.

These results show that adding a radical initiator to solution D greatly increases the decomposition efficiency when performing the process of D->C->D, and this result shows that adding a radical initiator to solution D in Experiment 3 below This is consistent with the results of higher decomposition efficiency.

On the other hand, as a result of examining the difference according to the presence or absence of the initiator (AIBN) added to the pre-impregnation in Experiment 2, it was confirmed that the specimen was more ductile in the case of D solution pre-impregnation + radical initiator.

[Experiment 3]

In Experiment 3, the change in decomposition efficiency was measured when the decomposition sequence of pre-impregnation was changed based on the sequence of using the pre-treatment D solution and the main treatment C solution, and when a radical initiator was additionally used.

First, a CFRP plate for aircraft was used as a raw material before disassembly. The size was 30 x 30 x 5 mm (1 g). For reference, Figure 4a is a photograph of the CFRP plate before disassembly.

As solutions used for decomposition, formic acid aqueous solution (C solution - 80%) and hydrogen peroxide aqueous solution (D solution - 34.5%) were used, respectively. Each C solution and D solution were used in a ratio of 1:20 by volume to CFRP.

Pre-impregnation was carried out at room temperature and pressure, and both pre-treatment and main treatment were performed at normal pressure and 90 °C.

As a radical initiator, 1 wt% of AIBN was used for each aqueous solution.

Decomposition efficiency was measured by thermal decomposition analysis (TGA) as in Experiment 2.

The sequence, whether or not a radical initiator was added, and the decomposition rate of each Example of Experiment 3 are as follows. In each sequence, all other conditions except those indicated below were the same.

Example pre-impregnated Pretreatment
(6 hours) main processing
(1 hours) decomposition rate
(TGA, %) note One C D C 89.3 radical initiator
no added 2 D D C 89.3 3 C D+ initiator C 99.7 Preprocessing D+
radical initiator 4 D D+ initiator C 97.9 5 C D C+initiator 99.5 Main processing C+
radical initiator 6 D D C+initiator 89.6

As can be seen from the above, it was found that the addition of a radical initiator to each of the pretreatment and main treatment of the decomposition reaction significantly increased the decomposition rate (by about 10%). For reference, in the case of CFRP recycling, preferably 95% or more, more preferably 98% or more should be decomposed.

On the other hand, in the case of adding a radical initiator, higher decomposition efficiency was shown in a specific sequence in pre-impregnation, pre-treatment decomposition reaction, and main treatment decomposition reaction. That is, in the case of Example 3 (C->D+initiator->C), the decomposition efficiency was higher than that of Example 5 (C->D+initiator).

In addition, in the case of Example 4 (D->D+initiator->C), a significantly higher increase in decomposition efficiency was shown compared to Example 6 (D->D->C+initiator).

As can be seen from the above, the addition of the radical initiator increases the decomposition efficiency, but especially when the D solution is used as the pretreatment solution and the C solution is used as the main treatment solution, the addition of the radical initiator to the pretreatment increases the overall decomposition efficiency. It can be seen that the rise

In addition, when using D solution as the pretreatment solution and C solution as the main treatment solution as above, the highest decomposition efficiency of 99.7% was shown under the same conditions, especially in the case of the sequence in which pre-impregnation is performed with C solution. For reference, FIGS. 4B to 4H are photographs of regenerated carbon fibers after decomposition according to Examples 1 to 6 of Experiment 2, respectively.

On the other hand, in this experiment, as a result of examining the difference according to the presence or absence of the addition of an initiator (AIBN) during pre-impregnation, the effect difference was insignificant in the case of C solution pre-impregnation + radical initiator, but in the case of D solution pre-impregnation + radical initiator, the specimen became more soft. could confirm that

Taken together, the radical initiator is considered to have a greater synergistic effect when added to solution D.

[Experiment 4]

On the other hand, the reaction can proceed more efficiently by changing the decomposition sequence according to the properties of the raw material (waste CFRP). 17 hours), the pre-treatment and main treatment reaction times can be further shortened.

In Experiment 4, the CFRP in the hydrogen tank was immediately disassembled without crushing after cutting. First, it was pre-impregnated in an aqueous formic acid solution at room temperature for 17 hours. Then, it was put in an aqueous hydrogen peroxide solution and pretreated for 4 hours.

In addition, after the pretreatment, it was put into an aqueous solution of formic acid and decomposed for 1 hour to complete the treatment.

The concentrations of each solution used were an aqueous solution of formic acid (solution C - 80%) and an aqueous solution of hydrogen peroxide (solution D - 34.5%). Each C solution and D solution were used in a ratio of 1:20 by volume to CFRP.

Both the pretreatment and main treatment were performed at normal pressure and 90°C.

5 is a result showing the reduction of the decomposition time according to the pre-impregnation in Experiment 4. Figure 5a is a photograph when pre-impregnated, Figure 5b is a photograph when not pre-impregnated. As a result of TGA analysis, there was no organic matter residue during pre-impregnation, but 20% organic matter residue was confirmed when pre-impregnation was not performed.

[Experiment 5]

In this experiment 5, a buffer solution (pH = 2.45) was initially added (1.17%) to compensate for the pH, and accordingly, the concentration was maintained at a constant level to maintain the degradation characteristics.

0.21 g of citric acid, 0.8 g of tartaric acid, and 0.5 g of phosphoric acid were dissolved in 100 ml of water by stirring, and then diluted to a total solution volume of 900 ml and stirred once more to prepare a buffer solution. The pH of the buffer solution was 2.45. After mixing, this buffer solution was added to solution D so that the pH reached 1.165.

Figure 6 is a graph showing the concentration and pH change according to the heating (90 ℃) time when a buffer solution is added or not added in the case of a solution (solution D) used in an exemplary embodiment of the present invention.

7 shows the results of repeated decomposition (heating temperature 90 ° C., reaction time per reaction time of about 5 hours per time) by adding a buffer solution to adjust the concentration in the case of a solution (solution D) used in an exemplary embodiment of the present invention. It is a graph that represents

As can be seen in FIG. 7, the solution of the exemplary embodiment of the present invention is capable of repeated decomposition and has excellent aqueous solution reusability, and it was possible to repeat up to 7 times.

In FIG. 7, the residual rate is the residual rate of organic matter according to TGA analysis. In FIG. 7, the increase in the buffer concentration after the third cycle is because the buffer solution was used after the third cycle. As can be seen from FIG. 7, as the number of repetitions increases, the decomposition rate also decreases, but the organic matter residual rate is insignificant up to the 7th time, but the decomposition itself does not occur from the 8th time.

Claims (20)

pretreating the thermosetting resin composite material in an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and
It includes; putting the pretreated thermosetting resin composite material in an aqueous hydrogen peroxide solution or an aqueous formic acid solution and performing a main treatment;
The decomposition method of the thermosetting resin composite material, characterized in that the aqueous solution used in the pretreatment and main treatment are of different types.
According to claim 1,
A decomposition method of a thermosetting resin composite material, characterized in that a radical initiator is added to the aqueous solution used for at least one of the pretreatment and main treatment.
According to claim 1,
The method further comprises a pre-impregnation step of pre-impregnating the thermosetting resin composite material in a formic acid solution or a hydrogen peroxide solution before pretreatment.
According to claim 3,
pre-impregnating the thermosetting resin composite material with an aqueous solution of formic acid;
pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution to which a radical initiator is added; and
The decomposition method of the thermosetting resin composite material further comprising the step of putting the pretreated thermosetting resin composite material into an aqueous solution of formic acid and performing a main treatment.
According to claim 3,
pre-impregnating the thermosetting resin composite material with an aqueous solution of formic acid;
pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution; and
The decomposition method of the thermosetting resin composite material further comprising the step of putting the pretreated thermosetting resin composite material into an aqueous solution of formic acid to which a radical initiator is added and performing a main treatment.
According to claim 3,
pre-impregnating the thermosetting resin composite material with an aqueous hydrogen peroxide solution;
pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution to which a radical initiator is added; and
The decomposition method of the thermosetting resin composite material further comprising the step of putting the pretreated thermosetting resin composite material into an aqueous solution of formic acid and performing a main treatment.
According to claim 3,
pre-impregnating the thermosetting resin composite material with an aqueous hydrogen peroxide solution;
pre-treating the pre-impregnated thermosetting resin composite material in an aqueous hydrogen peroxide solution; and
Further comprising the step of putting the pretreated thermosetting resin composite material in an aqueous formic acid solution to which a radical initiator is added and performing a main treatment,
The pre-impregnation is carried out at normal pressure and above room temperature and below 40 ° C,
The pretreatment is a decomposition method of a thermosetting resin composite material, characterized in that the treatment at normal pressure and 80 ℃ to 120 ℃.
According to claim 3,
pre-impregnating the thermosetting resin composite material with an aqueous hydrogen peroxide solution;
pre-treating the pre-impregnated thermosetting resin composite material in an aqueous solution of formic acid to which a radical initiator is added; and
The decomposition method of the thermosetting resin composite material further comprising the step of putting the pretreated thermosetting resin composite material into an aqueous hydrogen peroxide solution and performing a main treatment.
According to claim 3,
pre-impregnating the thermosetting resin composite material with an aqueous hydrogen peroxide solution;
pre-treating the pre-impregnated thermosetting resin composite material in an aqueous solution of formic acid; and
The decomposition method of the thermosetting resin composite material further comprising the step of putting the pretreated thermosetting resin composite material in an aqueous hydrogen peroxide solution to which a radical initiator is added and performing a main treatment.
According to claim 3,
The pre-impregnation is a decomposition method of a thermosetting resin composite material, characterized in that the treatment for 6 to 17 hours at room temperature and pressure.
According to claim 1,
The pretreatment is a decomposition method of a thermosetting resin composite material, characterized in that for 2 to 6 hours at normal pressure and 80 ~ 95 ℃ temperature.
According to claim 1,
The main treatment is a decomposition method of a thermosetting resin composite material, characterized in that the treatment for 1 to 3 hours at normal pressure and 80 ~ 95 ℃ temperature.
According to claim 1,
The formic acid concentration in the formic acid aqueous solution is 50 to 90%,
A decomposition method of a thermosetting resin composite material, characterized in that the hydrogen peroxide concentration in the hydrogen peroxide aqueous solution is 30 to 50%.
According to claim 2,
The decomposition method of the thermosetting resin composite material, characterized in that the radical initiator is added in an amount of 0.1 to 2 wt% in the formic acid aqueous solution or hydrogen peroxide aqueous solution.
According to claim 2,
The decomposition method of the thermosetting resin composite material, characterized in that the decomposition rate according to the thermogravimetric analysis (TGA) is 98% or more.
According to claim 1,
A decomposition method of a thermosetting resin composite material, characterized in that the decomposition characteristics are adjusted by adding a buffer solution in the pretreatment or main treatment step.
A pre-impregnation bath for pre-impregnating the thermosetting resin composite material in an aqueous solution of formic acid or an aqueous solution of hydrogen peroxide;
a pretreatment tank connected to the pre-impregnation tank to which the thermosetting resin composite material obtained from the pre-impregnation tank is transported and carrying an aqueous solution of formic acid or an aqueous solution of hydrogen peroxide; and
A main treatment tank connected to the pretreatment tank, transporting the thermosetting resin composite material obtained in the pretreatment tank, and carrying an aqueous hydrogen peroxide solution or an aqueous formic acid solution;
The decomposition device of the thermosetting resin composite material, characterized in that the aqueous solution supported in the pre-treatment tank and the main treatment tank are of different types.
As a disassembly kit for thermosetting resin composite materials,
a pre-impregnation composition comprising an aqueous formic acid solution or a hydrogen peroxide solution;
a pretreatment composition comprising an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and
A main treatment composition comprising an aqueous hydrogen peroxide solution or an aqueous formic acid solution;
A decomposition kit for a thermosetting resin composite material, characterized in that the aqueous solutions of the pretreatment composition and the main treatment composition are of different types.
According to claim 18,
The kit further comprises a radical initiator added to an aqueous solution of hydrogen peroxide or an aqueous solution of formic acid.
According to claim 19,
A decomposition kit for a thermosetting resin composite material, characterized in that 0.1 to 2 wt% or less of a radical initiator is added in the aqueous solution of hydrogen peroxide or the aqueous solution of formic acid.

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