KR20230045976A - Monomer composition for synthesising recycled plastic, prepration method thereof, and recycled plastic, molded product using the same - Google Patents

Abstract

The present invention relates to a monomer composition for synthesizing recycled plastics containing a high-purity aromatic diol compound recovered through recycling by chemical decomposition of polycarbonate resin, a manufacturing method thereof, and recycled plastics and molded products using the same. The present invention is to provide the monomer composition for synthesis of recycled plastics that can secure high purity and high yield aromatic diol compounds recovered through recycling by the chemical decomposition of the polycarbonate resin.

Description

Monomer composition for synthesizing recycled plastic, manufacturing method thereof, recycled plastic using the same, and molded article

The present invention relates to a monomer composition for synthesizing recycled plastic containing a high-purity aromatic diol compound recovered through recycling of a polycarbonate-based resin through chemical decomposition, a manufacturing method thereof, recycled plastic using the same, and a molded product.

In addition, the present invention relates to a monomer composition for synthesizing recycled plastics containing high value-added by-products recovered through recycling of polycarbonate-based resins by chemical decomposition, a manufacturing method thereof, recycled plastics using the same, and molded products.

Polycarbonate is a thermoplastic polymer and has excellent properties such as excellent transparency, ductility, and relatively low manufacturing cost.

Although polycarbonate is widely used for various purposes, environmental and health concerns have been continuously raised during waste disposal.

Currently, a physical recycling method is being performed, but in this case, there is a problem that quality degradation is accompanied, and thus, research on chemical recycling of polycarbonate is being conducted.

Chemical decomposition of polycarbonate is to obtain a monomeric aromatic diol compound (eg, Bisphenol A; BPA) through decomposition of polycarbonate, and then use it for polymerization to obtain high-purity polycarbonate. say

Thermal decomposition, hydrolysis, and alcohol decomposition are typically known for such chemical decomposition. Among them, the most common method is alcohol decomposition using a base catalyst, but in the case of methanol decomposition, there is a problem in that methanol, which is harmful to the human body, is used, and in the case of ethanol, high-temperature and high-pressure conditions are required and the yield is not high.

In addition, an alcohol decomposition method using an organic catalyst is known, but it has disadvantages in terms of economy.

An object of the present invention is to provide a monomer composition for synthesizing recycled plastic capable of securing a high-purity, high-yield aromatic diol compound recovered through recycling by chemical decomposition of a polycarbonate-based resin.

In addition, the present invention is to provide a method for preparing the monomer composition for synthesizing recycled plastic, recycled plastic using the monomer composition for synthesizing recycled plastic, and molded products.

In order to solve the above problems, in the present specification, an aromatic diol compound is included, and the recycled plastic monomer composition for synthesis has an impurity ratio of 1.2% or less according to the following formula 1 and an aromatic diol compound yield of 65 according to the following formula 2 %, and the monomer composition for synthesizing recycled plastics is recovered from polycarbonate-based resins, and provides a monomer composition for synthesizing recycled plastics.

[Equation 1]

Impurity ratio = {(total peak area on liquid chromatography - bisphenol A peak area on liquid chromatography) / total peak area on liquid chromatography} X 100,

[Equation 2]

Yield (%) = W ₁ /W ₀

In Equation 2, W ₀ is the mass of the aromatic diol compound obtained upon 100% decomposition of the polycarbonate-based resin, and W ₁ is the mass of the aromatic diol compound actually obtained.

In the present specification, the step of depolymerizing the polycarbonate-based resin; adding a base so that the pH of the depolymerization reaction product is 12 or higher; separating the carbonate precursor from the depolymerization reaction product by adding water after the addition of the base; and adding an acid so that the pH of the depolymerization product from which the carbonate precursor is separated becomes 4 or less.

In the present specification, a recycled plastic comprising a reaction product of the monomer composition for synthesizing the recycled plastic and the comonomer is also provided.

In the present specification, a molded article including the recycled plastic is also provided.

Hereinafter, a monomer composition for synthesizing recycled plastic according to specific embodiments of the present invention, a manufacturing method thereof, recycled plastic using the same, and a molded product will be described in detail.

Unless explicitly stated herein, terminology is used only to refer to specific embodiments and is not intended to limit the present invention.

As used herein, the singular forms also include the plural forms unless the phrases clearly dictate the contrary.

As used herein, the meaning of 'pH' is hydrogen ion concentration (pH), which is a numerical value representing the degree of acidity and alkalinity of a substance. The dissociation concentration of hydrogen ions can be obtained as a value expressed by taking the reciprocal of the logarithm, and is used as a measure of the acid and base strength of a substance.

As used herein, the meaning of 'comprising' specifies a particular property, domain, integer, step, operation, element, and/or component, and other particular property, domain, integer, step, operation, element, component, and/or group. does not exclude the presence or addition of

In this specification, terms including ordinal numbers such as 'first' and 'second' are used for the purpose of distinguishing one component from another component, and are not limited by the ordinal number. For example, within the scope of the present invention, a first element may also be termed a second element, and similarly, a second element may be termed a first element.

1. Monomer composition for synthesizing recycled plastics

According to one embodiment of the invention, the monomer composition for synthesizing recycled plastics, including an aromatic diol compound, has an impurity ratio of 1.2% or less according to the following formula 1, and an aromatic diol compound yield of more than 65% according to the following formula 2 , The monomer composition for synthesizing recycled plastics may be provided with a monomer composition for synthesizing recycled plastics, characterized in that recovered from a polycarbonate-based resin.

[Equation 1]

Impurity ratio = {(total peak area on liquid chromatography - bisphenol A peak area on liquid chromatography) / total peak area on liquid chromatography} X 100,

[Equation 2]

Yield (%) = W ₁ /W ₀

In Equation 2, W ₀ is the mass of the aromatic diol compound obtained upon 100% decomposition of the polycarbonate-based resin, and W ₁ is the mass of the aromatic diol compound actually obtained.

The inventors of the present invention have found that the monomer composition for synthesizing recycled plastics according to one embodiment is recovered through recycling by chemical decomposition of polycarbonate-based resins, but as the aromatic diol compound, which is the main recovery target, is secured in high purity and high yield, polycarbonate-based It was confirmed through experiments that excellent physical properties can be realized during resin synthesis, and the invention was completed.

In particular, the monomer composition for synthesizing recycled plastics (composition 1) of one embodiment, together with the monomer composition for synthesizing recycled plastics, comprising diethyl carbonate, wherein the diethyl carbonate is recovered from polycarbonate-based resins ( Composition 2) may be simultaneously obtained in the method for preparing a monomer composition for synthesizing recycled plastics, which will be described later.

That is, the present invention obtains a first composition containing an aromatic diol compound in high purity by recycling a polycarbonate-based resin by chemical decomposition, and at the same time obtains a second composition containing diethyl carbonate, a high added by-product. Technical may have special features.

Specifically, the monomer composition for synthesizing recycled plastic of one embodiment is characterized in that it is recovered from a polycarbonate-based resin. That is, as a result of recovering the polycarbonate-based resin to obtain the monomer composition for synthesizing recycled plastics according to one embodiment, the monomer composition for synthesizing recycled plastics containing an aromatic diol compound is also obtained.

The polycarbonate-based resin is meant to include all homopolymers or copolymers containing polycarbonate repeating units, and is a generic term for reaction products obtained through polymerization or copolymerization of monomers including an aromatic diol compound and a carbonate precursor. A homopolymer can be synthesized when it contains one type of carbonate repeating unit obtained by using only one type of aromatic diol compound and one type of carbonate precursor. In addition, as the monomer, one aromatic diol compound and two or more carbonate precursors are used, or two or more aromatic diol compounds and one carbonate precursor are used, or one aromatic diol compound and one carbonate precursor are used as well as one other diol. A copolymer can be synthesized when two or more carbonates are contained using the above. The homopolymer or copolymer may include all low molecular weight compounds, oligomers, and polymers according to the molecular weight range.

In addition, the monomer composition (first composition) for synthesizing recycled plastic according to one embodiment may include an aromatic diol compound. Specific examples of the aromatic diol compound, bis (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ketone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) , 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclonucleic acid (bisphenol Z), 2,2-bis(4-hydroxy-3,5-di Bromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 2,2-bis (4-hydroxy-3-chlorophenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1, 1-bis (4-hydroxyphenyl) -1-phenylethane or a mixture of two or more thereof; and the like. Preferably, the aromatic diol compound of the monomer composition for synthesizing recycled plastic (composition 1) of the embodiment may be 2,2-bis(4-hydroxyphenyl)propane (bisphenol A).

The aromatic diol compound is characterized in that it is recovered from the polycarbonate-based resin used to recover the monomer composition for synthesizing recycled plastics. That is, as a result of recovering the polycarbonate-based resin to obtain the monomer composition for synthesizing recycled plastic according to one embodiment, the aromatic diol compound is also obtained. Therefore, in order to prepare the monomer composition for synthesizing recycled plastic according to one embodiment, the case where a novel aromatic diol compound is externally added apart from recovery from the polycarbonate-based resin is not included in the scope of the aromatic diol compound of the present invention.

Specifically, recovered from the polycarbonate-based resin means obtained through a depolymerization reaction of the polycarbonate-based resin. The depolymerization reaction may be performed under acidic, neutral, or basic conditions, and particularly, the depolymerization reaction may be performed under basic (alkaline) conditions. In particular, the depolymerization reaction is preferably conducted in an ethanol solvent as described below.

Meanwhile, the monomer composition for synthesizing recycled plastic according to one embodiment may have a color coordinate b* value of 0 to 4.2, or 1 to 4, or 1 to 3, or 1.5 to 2.5, or 1.5 to 2.4, or 1.57 to 2.24. In addition, the monomer composition for synthesizing recycled plastic of one embodiment has a color coordinate L* of 94 or more, 95 or more, or 100 or less, or 94 to 100, or 94 to 98, or 95 to 100, or 95 to 98, or 95.9 to 95.9 It may be 97.1. In addition, the monomer composition for synthesizing recycled plastic according to one embodiment has a color coordinate of a* of 0.5 or less, or 0.3 or less, or 0 or more, or 0.01 or more, or 0 to 0.5, or 0 to 0.3, or 0.01 to 0.5, or 0.01 to 0.01. 0.3, or 0.01 to 0.25.

In the present invention, "color coordinates" means coordinates in the CIE Lab color space, which are color values specified by CIE (Commossion International de l'Eclairage), and any position in the CIE color space is L*, It can be expressed as a*, b* three coordinate values.

Here, the L* value indicates brightness, and L*=0 indicates black, and L*=100 indicates white. In addition, the a* value indicates which side of pure magenta and pure green the color with the corresponding color coordinates is biased, and the b* value indicates that the color with the corresponding color coordinates is pure yellow and pure yellow. Indicates which side of pure blue is biased.

Specifically, the a* value has a range of -a to +a. The maximum value of a* (a* max) represents pure red, and the minimum value of a* (a* min) represents pure green. In addition, the b* value has a range of -b to +b. The maximum value of b* (b* max) represents pure yellow, and the minimum value of b* (b* min) represents pure blue. For example, if the value of b* is a negative number, the color is biased towards pure blue, and if the value is positive, it means a color biased towards pure yellow. When b*=50 and b*=80 are compared, it means that b*=80 is located closer to pure yellow than b*=50.

When the color coordinate a* value of the monomer composition for synthesizing recycled plastics of one embodiment is excessively increased to more than 0.5 or the color coordinate L* value is excessively decreased to less than 94, the color characteristics of the monomer composition for synthesizing recycled plastics of one embodiment are become bad

On the other hand, if the color coordinate b* value of the monomer composition for synthesizing recycled plastics according to one embodiment is excessively increased to more than 4.2, the color of the monomer composition for synthesizing recycled plastics according to one embodiment is too biased toward yellow, resulting in poor color characteristics.

In addition, when the color coordinate b* value of the monomer composition for synthesizing recycled plastics according to one embodiment is excessively reduced to less than 0, the color of the monomer composition for synthesizing recycled plastics according to one embodiment is too blue, resulting in poor color characteristics.

An example of a method for measuring the color coordinates L*, a*, and b* values of the monomer composition for synthesizing recycled plastic according to the embodiment is not particularly limited, and various color characteristic measurement methods in the field of plastics can be applied without limitation.

However, as an example of a method for measuring the color coordinates L*, a*, and b* values of the monomer composition for synthesizing recycled plastic according to the embodiment, it can be measured in a reflection mode using a HunterLab UltraScan PRO Spectrophotometer.

On the other hand, the monomer composition for synthesizing recycled plastic of one embodiment has an aromatic diol compound purity of 99% or more, or 100% or less, or 99% to 100%, or 99% to 99.9%, or 99% to 99.8%, or 99%. % to 99.7%.

An example of a method for measuring the purity of the aromatic diol compound in the monomer composition for synthesizing recycled plastic according to the embodiment is not particularly limited, and for example, ¹ H NMR, ICP-MS analysis, HPLC analysis, UPLC analysis, etc. can be used without limitation. can For the specific methods, conditions, equipment, etc. of NMR, ICP-MS, HPLC, and UPLC, previously known various contents can be applied without limitation.

As an example of a method for measuring the purity of the aromatic diol compound of the monomer composition for synthesizing recycled plastics of one embodiment, the monomer composition for synthesizing recycled plastics of one embodiment is 1w% Acetonitrile (ACN) After dissolving in a solvent, the purity of bisphenol A (BPA) was analyzed by ultra performance liquid chromatography (UPLC) on a Waters HPLC system using an ACQUITY UPLC®BEH C18 1.7 μm (2.1 * 50 mm column).

As such, in the monomer composition for synthesizing recycled plastics of the embodiment, the purity of the aromatic diol compound, which is the main recovery target material, is extremely increased to 99% or more, thereby minimizing other impurities, thereby realizing excellent physical properties when synthesizing polycarbonate-based resins using this this is possible

Meanwhile, the monomer composition for synthesizing recycled plastic may further include impurities other than the aromatic diol compound. The impurities refer to all materials except aromatic diol compounds, which are the main recovery target materials of the present invention, and the specific types thereof are not greatly limited, but, for example, p-tert-butylphenol is mentioned. can

In addition, the monomer composition for synthesizing recycled plastic according to the embodiment has an impurity ratio of 1.2% or less, or 0.9% or less, or 0.8% or less, or 0.7% or less, or 0.5% or less, or 0.1% or more according to Formula 1, or 0.1% to 1.2%, or 0.1% to 0.9%, or 0.1% to 0.8%, or 0.1% to 0.7%, or 0.1% to 0.5%.

An example of a method for measuring the impurity ratio of the monomer composition for synthesizing recycled plastic according to the embodiment is not particularly limited, and LC analysis may be used, for example. As for the specific methods, conditions, equipment, etc. of the LC, previously known various contents can be applied without limitation.

As such, in the monomer composition for synthesizing recycled plastic according to the embodiment, the ratio of impurities other than the aromatic diol compound, which is the main recovery target material, is extremely reduced to 1.2% or less, and excellent physical properties can be realized when synthesizing polycarbonate-based resins using this. .

Meanwhile, the monomer composition for synthesizing recycled plastic according to one embodiment has an aromatic diol compound yield of greater than 65%, or greater than or equal to 67%, or greater than or equal to 68%, or less than or equal to 100%, or greater than 65% and less than or equal to 100%, or 67% to 100%. %, or 68% to 100%. The increase in the yield of the aromatic diol compound to more than 65% seems to be due to the method for preparing a monomer composition for synthesizing recycled plastics, which will be described later.

An example of a method for measuring the aromatic diol compound yield of the monomer composition for synthesizing recycled plastic according to one embodiment is not particularly limited, and can be calculated, for example, through Equation 2 below.

[Equation 2]

Yield (%) = W ₁ /W ₀

In Equation 2, W ₀ is the mass of the aromatic diol compound obtained upon 100% decomposition of the polycarbonate-based resin, and W ₁ is the mass of the aromatic diol compound actually obtained.

In Formula 2, for the mass of the aromatic diol compound, various generally known mass measurement methods can be used without limitation, and a balance can be used, for example.

As such, the yield of the aromatic diol compound, which is the main recovery target material, in the monomer composition for synthesizing recycled plastic according to the embodiment is extremely increased to more than 65%, so that the efficiency of the recycling process for the polycarbonate-based resin can be improved.

Meanwhile, in the monomer composition for synthesizing recycled plastic according to the embodiment, diethyl carbonate may be obtained as a by-product. The diethyl carbonate is characterized in that it is recovered from the polycarbonate-based resin used for recovering the monomer composition for synthesizing recycled plastic according to the embodiment.

That is, as a result of recovering the polycarbonate-based resin to obtain the monomer composition for synthesizing recycled plastic according to one embodiment, diethyl carbonate is also obtained. Therefore, in order to prepare the monomer composition for synthesizing recycled plastic according to the embodiment, the case where new diethyl carbonate is externally added separately from recovery from the polycarbonate-based resin is not included in the diethyl carbonate category of the embodiment. .

Specifically, recovered from the polycarbonate-based resin means obtained through a depolymerization reaction of the polycarbonate-based resin. The depolymerization reaction may be carried out under acidic, neutral or basic conditions, and in particular, the depolymerization reaction may proceed under basic (alkaline) conditions. In particular, the depolymerization reaction is preferably conducted in an ethanol solvent as described below.

Since the main recovery target material in the monomer composition for synthesizing recycled plastics of the embodiment is an aromatic diol compound, the diethyl carbonate can be separated and recovered as a by-product from the monomer composition for synthesizing recycled plastics of the embodiment.

The monomer composition for synthesizing recycled plastic according to one embodiment may be used as a raw material for producing various recycled plastics (eg, polycarbonate (PC)) described later.

The monomer composition for synthesizing recycled plastics of the embodiment may further include some small amounts of other additives and solvents, and the type of specific additives or solvents is not greatly limited, and an aromatic diol compound recovery process by depolymerization of polycarbonate-based resin Various materials widely used in can be applied without limitation.

The monomer composition for synthesizing recycled plastics according to one embodiment may be obtained by a method for preparing a monomer composition for synthesizing recycled plastics described below. That is, the monomer composition for synthesizing recycled plastic according to an embodiment of the present invention is obtained through various filtration, purification, washing, and drying processes in order to secure only aromatic diol compounds, which are the main recovery target materials, in high purity after the depolymerization reaction of the polycarbonate-based resin. applicable

2. Manufacturing method of monomer composition for synthesizing recycled plastics

According to another embodiment of the invention, the step of depolymerizing the polycarbonate-based resin; adding a base so that the pH of the depolymerization reaction product is 12 or higher; separating the carbonate precursor from the depolymerization reaction product by adding water after the addition of the base; and adding an acid so that the pH of the depolymerization reaction product from which the carbonate precursor is separated becomes 4 or less.

In the process of recycling the polycarbonate-based resin by chemical decomposition, as in the method for preparing the monomer composition for synthesizing recycled plastics of the other embodiment, the present inventors adjusted the pH of the depolymerized polycarbonate-based resin step by step, The present invention was completed after confirming through experiments that an aromatic diol compound, which is a synthetic target material, can be obtained in high purity and in high yield within a short processing time.

In particular, distillation has been conventionally used to remove carbonate monomers from depolymerized polycarbonate-based resins, but in the present invention, an aromatic diol compound can be obtained in a higher yield in a faster process time than in distillation through stepwise adjustment of pH instead of distillation. There are advantages.

Specifically, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may include a step of depolymerizing a polycarbonate-based resin.

The polycarbonate-based resin is meant to include all homopolymers or copolymers containing polycarbonate repeating units, and is a generic term for reaction products obtained through polymerization or copolymerization of monomers including an aromatic diol compound and a carbonate precursor. A homopolymer can be synthesized when it contains one type of carbonate repeating unit obtained by using only one type of aromatic diol compound and one type of carbonate precursor. In addition, as the monomer, one aromatic diol compound and two or more carbonate precursors are used, or two or more aromatic diol compounds and one carbonate precursor are used, or one aromatic diol compound and one carbonate precursor are used as well as one other diol. A copolymer can be synthesized when two or more carbonates are contained using the above. The homopolymer or copolymer may include all low molecular weight compounds, oligomers, and polymers according to the molecular weight range.

The polycarbonate-based resin can be applied regardless of various forms and types, such as a new polycarbonate-based resin produced through synthesis, a recycled polycarbonate-based resin produced through a recycling process, or polycarbonate-based resin waste.

However, if necessary, the efficiency of the process of recovering the aromatic diol compound and the carbonate precursor from the polycarbonate resin may be increased by performing a pretreatment process of the polycarbonate resin before proceeding with the depolymerization reaction of the polycarbonate resin. there is. Examples of the pretreatment process include washing, drying, pulverization, and decomposition of a glycol, and the specific method of each pretreatment process is not limited, and an aromatic diol compound by depolymerization of polycarbonate-based resin, and a carbonate precursor recovery process Various methods widely used in can be applied without limitation.

In the depolymerization reaction of the polycarbonate-based resin, the depolymerization reaction may be performed under acidic, neutral, or basic conditions, and particularly, the depolymerization reaction may proceed under basic (alkaline) conditions. The type of the base is not particularly limited, and examples thereof include sodium hydroxide (NaOH) or potassium hydroxide (KOH). The base is a base catalyst that acts as a catalyst, and has an advantage in economic efficiency compared to organic catalysts mainly used under mild conditions. More specifically, during the depolymerization reaction of the polycarbonate-based resin, the depolymerization reaction may proceed within a pH range of greater than 8 and less than 12.

0.5 mol or less, or 0.4 mol or less, or 0.3 mol or less, or 0.1 mol or more, or 0.2 mol or more, or 0.1 mol to 0.5 mol, or 0.1 mol relative to 1 mol of the polycarbonate-based resin during the depolymerization reaction of the polycarbonate-based resin. to 0.4 moles, or 0.1 moles to 0.3 moles, or 0.2 moles to 0.5 moles, or 0.2 moles to 0.4 moles, or 0.2 moles to 0.3 moles. When the polycarbonate-based resin is reacted with a base in an amount greater than 0.5 mol relative to 1 mol of the polycarbonate-based resin during the depolymerization reaction, impurities increase due to the effect of increasing the amount of alkali salt, reducing the purity of the target recovery material and improving the economics of the catalytic reaction. There is a limit to decrease.

In addition, the depolymerization reaction of the polycarbonate-based resin may proceed in a solvent including ethanol. The present invention has the advantage of being able to stably obtain bisphenol A, which is a high-purity monomer, by decomposing a polycarbonate-based resin with a solvent including ethanol, and additionally obtaining high value-added diethyl carbonate as a reaction by-product.

The amount of ethanol may be 5 to 15 moles or 8 to 13 moles per mole of the polycarbonate-based resin. Since the ethanol has good solubility in bisphenol A, ethanol within the above range must be necessarily included. When the content of ethanol is excessively reduced to less than 5 moles relative to 1 mole of the polycarbonate-based resin, alcohol decomposition of the polycarbonate-based resin is difficult to sufficiently proceed. On the other hand, if the content of ethanol is excessively increased to more than 15 moles relative to 1 mole of the polycarbonate-based resin, the economic feasibility of the process may decrease due to excessive use of alcohol.

The solvent in which the depolymerization reaction of the polycarbonate-based resin proceeds is at least one selected from the group consisting of tetrahydrofuran, toluene, methylene chloride, chloroform, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate and dipropyl carbonate, in addition to ethanol. An organic solvent may be further included.

The organic solvent may include tetrahydrofuran, toluene, methylene chloride, chloroform, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, dipropyl carbonate, or a mixture of two or more thereof.

More preferably, methylene chloride may be used as the organic solvent. When methylene chloride is used as an organic solvent mixed with ethanol, there is an advantage in that the solubility of polycarbonate is improved and reactivity can be improved.

The amount of the organic solvent may be 16 to 20 moles, or 16 to 18 moles based on 1 mole of the polycarbonate-based resin. In addition, the content of the organic solvent may be 1.5 to 2 moles relative to 1 mole of ethanol. By mixing the polycarbonate-based resin, ethanol, and an organic solvent within the above range, there is an advantage in that a necessary level of polymer unitization (Depolymerization) reaction can proceed.

Meanwhile, the temperature at which the depolymerization of the polycarbonate-based resin proceeds is not particularly limited, but may be, for example, 20 °C to 100 °C or 50 °C to 70 °C. In addition, the depolymerization reaction of the polycarbonate-based resin may proceed for 1 hour to 30 hours, or 4 hours to 6 hours.

Specifically, the conditions are mild process conditions compared to the existing pressurized / high temperature process, and the process can be performed in a mild process compared to the pressurized / high temperature process by performing stirring under the above conditions, especially at 50 ° C. When stirring at 70 ° C. for 4 to 6 hours, there is an advantage in obtaining the most efficient results in terms of reproducibility and recognition.

That is, the present invention controls the type and amount of the mixed solvent and the type and content of the base catalyst even without using an organic catalyst, so that a high-purity aromatic diol compound (e.g., Bisphenol A) can be obtained, and diethyl carbonate can be obtained as a by-product by using an ethanol solvent.

More specifically, the step of depolymerizing the polycarbonate-based resin may include a first step of dissolving the carbonate-based resin in an organic solvent; and a second step of stirring by adding a catalyst solution including ethanol and a base. In the first and second steps, the contents of ethanol, organic solvent, base, and polycarbonate-based resin are the same as described above.

Meanwhile, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may include adding a base so that the pH of the depolymerization reaction product becomes 12 or more, or 12 to 14. A strong base may be used as the base, and examples thereof include sodium hydroxide (NaOH).

In the step of adding a base so that the pH of the depolymerization reaction product becomes 12 or higher, the aromatic diol compound included in the depolymerization reaction product may be converted into a salt of the aromatic diol compound.

Accordingly, in the step of separating the carbonate precursor from the depolymerization reaction product by adding water after adding the base, which will be described later, the depolymerization reaction product comprises an aqueous layer containing a salt of an aromatic diol compound and an organic solvent layer containing diethyl carbonate. Layers separated by can be formed. Since the salt of the aromatic diol compound has hydrophilicity, it may be included in the water layer of water and the organic solvent, and since the diethyl carbonate has hydrophobicity, it may be included in the organic solvent layer of water and the organic solvent. Accordingly, it is possible to easily separate the main product, the aromatic diol compound, and the by-product, diethyl carbonate, only by a simple process of changing the pH.

Meanwhile, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may include separating a carbonate precursor from a depolymerization reaction product by adding water after adding the base. Accordingly, the separated carbonate precursor may include diethyl carbonate.

As described above, after the step of adding a base so that the pH of the depolymerization reaction product is 12 or higher, the step of separating the carbonate precursor from the depolymerization reaction product by adding water after the addition of the base proceeds, and the depolymerization The reaction product forms a layer divided into an aqueous layer containing a salt of an aromatic diol compound and an organic solvent layer containing diethyl carbonate, from which a layer divided into an organic solvent layer containing diethyl carbonate can be separated. there is.

In the step of separating the carbonate precursor from the depolymerization reaction product by adding water after the addition of the base, the organic layer may be separated from the water layer, and the carbonate precursor may be recovered from the separated organic layer. Specific separation conditions for separating the organic layer from the water layer are not significantly limited, and various conventionally known purification techniques can be applied without limitation to specific separation equipment and methods. However, for example, a separatory funnel may be used.

The separated carbonate precursor may be recycled without a separate purification process, or may be recycled through separation and purification such as conventional extraction, adsorption, and drying, if necessary. Specific purification conditions are not significantly limited, and various conventionally known purification techniques can be applied without limitation to specific purification equipment and methods.

Meanwhile, a step of adding an acid may be included so that the pH of the depolymerization product from which the carbonate precursor is separated becomes 4 or less, or 2 or less, or 1 to 4, or 1 to 2. Through this, an aromatic diol compound, which is a main recovery material, is obtained, which corresponds to the embodiment of the monomer composition for synthesizing recycled plastic.

As described above, after the step of adding a base so that the pH of the depolymerization reaction product is 12 or higher, the step of separating the carbonate precursor from the depolymerization reaction product by adding water after the addition of the base proceeds, and the depolymerization The reaction product may form a layer divided into an aqueous layer containing a salt of an aromatic diol compound and an organic solvent layer containing diethyl carbonate. As the organic layer is separated from the water layer, the carbonate precursor is obtained from the depolymerization reaction product. An aqueous layer containing a salt of an aromatic diol compound remains in the depolymerization reaction product after the separation step.

Since the main recovery target material of the present invention is an aromatic diol compound, a salt of the aromatic diol compound included in the water layer may be converted into an aromatic diol compound through an additional acid neutralization process. That is, in the step of adding an acid so that the pH of the depolymerization product from which the carbonate precursor is separated becomes 4 or less, the salt of the aromatic diol compound included in the depolymerization product may be converted into an aromatic diol compound.

A strong acid may be used as the acid, and examples thereof include hydrochloric acid (HCl).

Meanwhile, in the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment, after the step of adding an acid so that the pH of the depolymerization product from which the carbonate precursor is separated becomes 4 or less, the carbonate precursor is separated from the depolymerization reaction product. Further steps may be included.

Specifically, the step of purifying the depolymerization product from which the carbonate precursor is separated may include a step of washing the depolymerization product from which the carbonate precursor is separated. Further, the step of purifying the depolymerization product from which the carbonate precursor is separated may include an adsorption and purification step of the depolymerization product from which the carbonate precursor is separated. Further, the step of purifying the depolymerization product from which the carbonate precursor is separated may include recrystallization of the depolymerization product from which the carbonate precursor is separated.

the washing step; the adsorption purification step; or the recrystallization step; Each order is not particularly limited and may proceed in any order, but for example, the washing step; the adsorption purification step; And the recrystallization step; may proceed in the order. the washing step; the adsorption purification step; And the recrystallization step may be repeated at least once or more. For specific washing, adsorption, recrystallization equipment and methods, various previously known purification technologies can be applied without limitation.

In the step of washing the depolymerization product from which the carbonate precursor is separated, the depolymerization product from which the carbonate precursor is separated may contain an aromatic diol compound. However, since various impurities remain during the recovery process of obtaining the aromatic diol compound, washing may be performed to sufficiently remove them to secure a high-purity aromatic diol compound.

Specifically, the washing step may include washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less, or 20 ° C. or more and 30 ° C. or less; and washing with a solvent at a temperature of 40 °C or more and 80 °C or less, or 40 °C or more and 60 °C or less, or 45 °C or more and 55 °C or less. The temperature condition refers to the temperature inside the washing vessel at which washing with the solvent is performed, and various heating mechanisms may be applied without limitation to maintain a high temperature beyond room temperature.

In the washing step, the step of washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less may be performed first, and the step of washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less may be performed later. In addition, the step of washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less may be performed first, and the step of washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less may be performed later.

More preferably, in the washing step, the washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less; may be performed first, and the washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less may be performed later. there is. Accordingly, corrosion of the reactor by strong acid after the neutralization step can be minimized.

Washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less; And the step of washing with a solvent at a temperature of 40 ° C. or higher and 80 ° C. or lower may be repeated at least once or more.

In addition, washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less, if necessary; And after the step of washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less, a process of removing the remaining solvent through filtration may be further performed.

More specifically, the difference between the temperature of washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less and the temperature of washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less is 20 ° C. or more and 50 ° C. or less. can

The difference between the temperature of washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less and the temperature of washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less is the temperature of 40 ° C. or more and 80 ° C. or less. It means a value obtained by subtracting the temperature of washing with a solvent from the temperature of 10 ° C. or more and 30 ° C. or less from the temperature of washing with a solvent in .

When the difference between the temperature of washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less and the temperature of washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less is excessively reduced to less than 20 ° C., impurities are removed. Hard enough to remove.

If the difference between the temperature of the solvent washing at a temperature of 40 ° C. or more and 80 ° C. or less and the temperature of the solvent washing at a temperature of 10 ° C. or more and 30 ° C. or less increases excessively to more than 50 ° C. Severe conditions may be formed to maintain temperature conditions, reducing the efficiency of the process.

The solvent used in the washing step may include one of water, alcohol, and an organic solvent. As the organic solvent, tetrahydrofuran, toluene, methylene chloride, chloroform, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, dipropyl carbonate, or a mixture of two or more thereof may be used.

The solvent used in the washing step may be used in a weight ratio of 1 part by weight or more and 30 parts by weight or less, or 1 part by weight or more and 10 parts by weight or less, based on 1 part by weight of the polycarbonate-based resin used in the depolymerization reaction.

More specifically, the solvent in the step of washing with a solvent at a temperature of 10 ° C. or more and 30 ° C. or less may be an organic solvent. Methylene chloride may be preferably used as the organic solvent. In this case, the organic solvent may be used in an amount of 1 part by weight or more and 10 parts by weight or less based on 1 part by weight of the polycarbonate-based resin.

In addition, the solvent in the step of washing with a solvent at a temperature of 40 ° C. or more and 80 ° C. or less may be water. When the water is used, residual salt-type impurities can be effectively removed. And, at this time, the solvent may be used in an amount of 1 part by weight or more and 10 parts by weight or less based on 1 part by weight of the polycarbonate-based resin.

The adsorption and purification step of the depolymerization product from which the carbonate precursor is separated may include adsorbing and purifying the depolymerization product from which the carbonate precursor is separated, and then removing the adsorbent. In the step of adding an adsorbent to the depolymerization product from which the carbonate precursor is separated, adsorbing and purifying the adsorbent, and then removing the adsorbent, the depolymerization product may be brought into contact with the adsorbent.

As an example of the adsorbent, activated carbon, charcoal, or a mixture thereof may be used. The activated carbon is a black carbon material with micropores prepared by subjecting raw materials to a carbonization process at about 500 ° C and an activated carbon process at about 900 ° C. Depending on the type, various activated carbons such as plant-based, coal-based, petroleum-based, and waste activated carbons can be applied without limitation.

For a more specific example, plant-based activated carbon may include coconut activated carbon, wood activated carbon, and sawdust activated carbon. In addition, as the coal-based activated carbon, lignite activated carbon, bituminous carbon activated carbon, and anthracite activated carbon may be mentioned. In addition, petroleum-based activated carbon includes petroleum coke activated carbon and oil carbon activated carbon. In addition, as waste activated carbon, synthetic resin activated carbon and pulp activated carbon may be mentioned.

The adsorbent may include at least one type of activated carbon selected from the group consisting of plant-based activated carbon, coal-based activated carbon, petroleum-based activated carbon, and waste activated carbon. That is, the adsorbent may include plant-based activated carbon, coal-based activated carbon, petroleum-based activated carbon, waste activated carbon, or a mixture of two or more thereof.

More specifically, the adsorbent may include at least one type of activated carbon selected from the group consisting of coconut activated carbon, lignite activated carbon, anthracite activated carbon, and bituminous carbon activated carbon. That is, the adsorbent may include coconut activated carbon, lignite activated carbon, anthracite activated carbon, bituminous carbon activated carbon, or a mixture of two or more thereof.

Adsorption purification conditions by the adsorbent are not particularly limited, and various conventional adsorption purification conditions may be used without limitation. However, for example, the input amount of the adsorbent may be 40% to 60% by weight compared to the polycarbonate-based resin, the adsorption time may be 1 hour to 5 hours, and the adsorption method may be agitated adsorption or an adsorption tower for Lab. can

If necessary, a step of adding a solvent to the depolymerization product from which the carbonate precursor is separated may be further included prior to the step of adsorbing and purifying the depolymerization product from which the carbonate precursor is separated and then removing the adsorbent. An example of the solvent may be ethanol, and the ethanol may be added at a ratio of 1 to 20 moles, 10 to 20 moles, or 15 to 20 moles based on 1 mole of the polycarbonate-based resin. Through the step of adding a solvent to the depolymerization product from which the carbonate precursor is separated, the aromatic diol compound crystals included in the depolymerization product from which the carbonate precursor is separated can be redissolved in the solvent.

Meanwhile, in the step of recrystallizing the depolymerization product from which the carbonate precursor is separated, various impurities contained in the depolymerization product from which the carbonate precursor is separated can be sufficiently removed to obtain a high-purity aromatic diol compound.

Specifically, the recrystallization step may include recrystallization by adding water to the depolymerization product from which the carbonate precursor is separated. Through the process of recrystallizing by adding water to the depolymerization product from which the carbonate precursor is separated, the solubility of the aromatic diol compound or its salt contained in the depolymerization product is increased, and the crystals or impurities intervening between the crystals are used as a solvent as much as possible. Since the dissolved aromatic diol compound has poor solubility compared to impurities, it can be easily precipitated as crystals of the aromatic diol compound through the difference in solubility when the temperature is lowered thereafter.

More specifically, in the recrystallization step by adding water to the depolymerization product from which the carbonate precursor is separated, 200 to 400 moles or 250 to 350 moles of water may be used per mole of the polycarbonate-based resin. If too little water is used, the temperature for dissolving the aromatic diol compound contained in the depolymerization product from which the carbonate precursor is separated becomes too high, resulting in poor process efficiency and difficulty in removing impurities through recrystallization. On the other hand, if an excessive amount of water is used, the solubility of the aromatic diol compound contained in the depolymerization product from which the carbonate precursor is separated is excessively high, reducing the yield of the aromatic diol compound recovered after recrystallization, and the process due to the use of a large amount of solvent Efficiency may decrease.

If necessary, after the step of recrystallizing the depolymerization reaction product from which the carbonate precursor is separated, a step of removing remaining impurities through filtration or adsorption may be additionally performed.

In addition, if necessary, after the recrystallization step, a drying step; may further include. The remaining solvent may be removed through the drying, and specific drying conditions are not particularly limited, but drying may be performed at a temperature of, for example, 10 °C to 100 °C or 10 °C to 50 °C. For the specific drying equipment and method used in the drying, various previously known drying techniques can be applied without limitation.

3. Recycled plastic

According to another embodiment of the present invention, recycled plastic including the reaction product of the monomer composition for synthesizing recycled plastic and the comonomer of one embodiment may be provided.

Information about the monomer composition for synthesizing recycled plastics according to one embodiment includes all of the above-described contents in the one embodiment and the other embodiments, respectively.

Examples corresponding to the recycled plastics are not particularly limited, and various plastics synthesized from aromatic diol compounds such as bisphenol A and carbonate precursors such as dimethyl carbonate, diethyl carbonate, or ethylmethyl carbonate as monomers are applicable without limitation, More specific examples include polycarbonate-based resins.

The polycarbonate-based resin is meant to include all homopolymers or copolymers containing polycarbonate repeating units, and is a generic term for reaction products obtained through polymerization or copolymerization of monomers including an aromatic diol compound and a carbonate precursor. A homopolymer can be synthesized when it contains one type of carbonate repeating unit obtained by using only one type of aromatic diol compound and one type of carbonate precursor. In addition, as the monomer, one aromatic diol compound and two or more carbonate precursors are used, or two or more aromatic diol compounds and one carbonate precursor are used, or one aromatic diol compound and one carbonate precursor are used as well as one other diol. A copolymer can be synthesized when two or more carbonates are contained using the above. The homopolymer or copolymer may include all low molecular weight compounds, oligomers, and polymers according to the molecular weight range.

More specifically, in the recycled plastic including the reaction product of the monomer composition for synthesizing recycled plastic and the comonomer of one embodiment, a carbonate precursor may be used as the comonomer. Specific examples of the carbonate precursor include phosgene, triphosgene, diphosgene, bromophosgene, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, diphenyl carbonate, ditoryl carbonate, bis(chlorophenyl) carbonate, m - Cresyl carbonate, dinaphthyl carbonate, bis(diphenyl) carbonate or bishaloformate.

An example of a reaction process of a monomer composition for synthesizing recycled plastic and a comonomer for synthesizing the polycarbonate-based resin is not greatly limited, and various previously known polycarbonate manufacturing methods can be applied without limitation.

However, as an example of the polycarbonate manufacturing method, a polycarbonate manufacturing method including polymerizing a composition including a monomer composition for synthesizing recycled plastic and a comonomer may be used. In this case, the polymerization may be performed by interfacial polymerization, and during the interfacial polymerization, the polymerization reaction is possible at normal pressure and low temperature, and the molecular weight can be easily controlled.

The polymerization temperature may be 0 °C to 40 °C, and the reaction time may be 10 minutes to 5 hours. In addition, the pH may be maintained at 9 or higher or 11 or higher during the reaction.

The solvent that can be used for the polymerization is not particularly limited as long as it is a solvent used for polymerization of polycarbonate in the art, and for example, halogenated hydrocarbons such as methylene chloride and chlorobenzene can be used.

In addition, the polymerization may be performed in the presence of an acid binder, and an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine may be used as the acid binder.

In addition, in order to control the molecular weight of the polycarbonate during the polymerization, polymerization may be performed in the presence of a molecular weight regulator. Alkylphenols having 1 to 20 carbon atoms may be used as the molecular weight modifier, and specific examples thereof include p-tert-butylphenol, p-cumylphenol, decylphenol, dodecylphenol, tetradecylphenol, hexadecylphenol, octadecylphenol, eicosylphenol, docosylphenol or triacontylphenol. The molecular weight modifier may be added before polymerization, during polymerization, or after polymerization. The molecular weight modifier may be used in an amount of 0.01 to 10 parts by weight or 0.1 to 6 parts by weight based on 100 parts by weight of the aromatic diol compound, and a desired molecular weight may be obtained within this range.

In addition, in order to promote the polymerization reaction, reactions such as tertiary amine compounds such as triethylamine, tetra-n-butylammonium bromide, and tetra-n-butylphosphonium bromide, quaternary ammonium compounds, and quaternary phosphonium compounds Accelerators may additionally be used.

4. Molded articles

According to another embodiment of the invention, a molded article including the recycled plastic of the other embodiment may be provided. The contents of the recycled plastic include all of the contents described above in the other embodiment.

The molded product may be obtained by applying various known plastic molding methods to the recycled plastic without limitation, and examples of the molding method include injection molding, foam injection molding, blow molding, or extrusion molding.

Examples of the molded article are not greatly limited, and can be applied without limitation to various molded articles using plastic. Examples of the molded article include automobile parts, electrical and electronic products, communication products, household goods, building materials, optical parts, exterior materials, and the like.

In addition to the recycled plastics of the other embodiments, the molded article may optionally contain one or more additives selected from the group consisting of antioxidants, plasticizers, antistatic agents, nucleating agents, flame retardants, lubricants, impact modifiers, optical whitening agents, ultraviolet absorbers, pigments, and dyes. may additionally include.

As an example of the method for manufacturing the molded product, after mixing the recycled plastic and additives of the other embodiment using a mixer, extruding them with an extruder to produce pellets, drying the pellets, and then injecting them with an injection molding machine can include

According to the present invention, a monomer composition for synthesizing recycled plastic containing a high-purity, high-yield aromatic diol compound recovered through recycling by chemical decomposition of a polycarbonate-based resin, a manufacturing method thereof, and a recycled plastic using the same, and a molded article are provided It can be.

The invention is explained in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

<Examples and Comparative Examples: Preparation of recycled bisphenol A monomer composition>

Example 1

(1. Decomposition step) After dissolving 1 mol of pretreated waste polycarbonate (PC) in 17 mol of methylene chloride (MC), it was added together with 11 mol of ethanol (EtOH) and 0.25 mol of sodium hydroxide (NaOH) to a 3L high-pressure reactor. The PC depolymerization reaction was performed by stirring at 60 °C for 6 hours.

(2. Basification step) The product of the depolymerization reaction was cooled to 30° C. or less, and then the product containing bisphenol A was basified with 2 mol of 40% sodium hydroxide (NaOH) until pH reached 14. .

After (3. layer separation step), water was additionally added to form a water layer and a methylene chloride (MC) layer. The methylene chloride (MC) layer located at the bottom was removed using a separatory funnel, and the water layer located at the top was recovered.

(4. Acidification step) The recovered water layer was acidified until the pH reached 1-2 by adding 10% HCl and water. Thereafter, bisphenol A was recovered by filtering through vacuum filtration.

(5-1. Additional purification step - redissolution step) After that, bisphenol A was added to 16.6 mol of ethanol and dissolved again.

After (5-2. Additional purification step-adsorption step), lignite activated carbon was added as an adsorbent at a ratio of 50% by weight to waste polycarbonate, purified through adsorption for 3 hours, and then lignite activated carbon was removed through filtration.

After (5-3. Additional purification step-recrystallization step), 300 mol of water was added and bisphenol A was recrystallized, and bisphenol A (BPA) crystals were recovered through vacuum filtration of the resulting slurry at 20 to 30 °C.

(6. Drying step) After that, a recycled bisphenol A monomer composition in which recycled bisphenol A (BPA) was recovered was prepared by vacuum drying in a convection oven at 40 °C.

Example 2

Recycling in the same manner as in Example 1, except that the following (washing step) was added between (4. Acidification step) and (5-1. Additional purification step-redissolution step) of Example 1. A bisphenol A monomer composition was prepared.

(Washing step) First washing at 20 ~ 30 ℃ using methylene chloride (MC) 1 times the mass of PC used, followed by vacuum filtration. The filtrate was washed a second time at a temperature of 50° C. with water three times the mass of PC used.

Example 3

A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that (5-2. Additional purification step-adsorption step) of Example 1 was not performed.

Comparative Example 1

A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that the following (distillation step) was performed instead of (3. layer separation step) and (4. acidification step) of Example 1. .

(Distillation step) After that, diethyl carbonate (DEC), a by-product, was recovered through low-temperature distillation of the product lowered to pH less than 2 under reduced pressure from 250 mbar, 20 to 30 °C to 30 mbar, 30 °C.

<Experimental example>

For the recycled bisphenol A monomer compositions or by-products obtained in the above Examples and Comparative Examples, physical properties were measured by the following method, and the results are shown in Table 1.

1. Purity

The recycled bisphenol A monomer composition was dissolved in an acetonitrile (ACN) solvent at 1w% under normal pressure and 20 ~ 30 ℃ conditions, and then UPLC (ultra Performance liquid chromatography) was used to analyze the purity of bisphenol A (BPA).

2. Color coordinates (L*, a*, b*)

The recycled bisphenol A monomer composition was analyzed in reflection mode using a HunterLab UltraScan PRO spectrophotometer.

3. Yield

The weight of BPA produced when the polycarbonate used in the reaction was 100% decomposed was measured, and the weight of the obtained BPA was measured to calculate the yield of BPA as shown in Equation 2 below.

[Equation 2]

Yield (%) = W ₁ /W ₀

In Equation 2, W ₀ is the mass of BPA obtained upon 100% decomposition, and W ₁ is the mass of BPA actually obtained. Specifically, when about 100 g of polycarbonate is decomposed, the theoretical mass of BPA obtained at 100% decomposition is 89 g. If the mass of BPA actually obtained is 80 g, the yield is 80/89 * 100 = 90%.

4. Impurity ratio

1 ml of the recycled bisphenol A monomer composition was taken as a sample and subjected to liquid chromatography (LC) analysis under the following conditions, and the impurity ratio was obtained by the following formula 1. As a result of measurement using liquid chromatography, all substances except for bisphenol A were regarded as impurities.

<Liquid chromatography (LC) conditions>

① Column: HP-1 (L:30m, ID:0.32mm, film:1.05m)

② Injection volume: 1 μl

③ Inlet

Temp.: 260 ℃, Pressure: 6.92psi, Total flow: 64.2ml/min,

*Split flow: 60ml/min, spill ratio: 50:1

④ Column flow: 1.2ml/min

⑤ Oven temp.: 70℃/3min-10℃/min-280℃/41min　(Total 65min)

⑥ Detector

Temp.:280℃, _H2 : 35ml/min, Air: 300ml/min, He: 20ml/min

⑦ GC Model: Agilent 7890

[Equation 1]

Impurity ratio = {(total peak area on liquid chromatography - bisphenol A peak area on liquid chromatography) / total peak area on liquid chromatography} X 100.

Experimental example measurement result division water(%) L* a* b* transference number(%) impurities(%) Example 1 99.3 96.4 0.12 1.82 72 0.7 Example 2 99.7 97.1 0.01 1.57 68 0.3 Example 3 99.1 95.9 0.25 2.24 73 0.9 Comparative Example 1 99.1 96.0 0.34 2.49 65 0.9

As shown in Table 1, the recycled bisphenol A monomer compositions obtained in Examples 1 to 3 exhibited high purity of 99.1% to 99.7%. In addition, the recycled bisphenol A monomer compositions obtained in Examples 1 to 3 exhibited excellent optical properties with color coordinates L* of 95.9 to 97.1, a* of 0.01 to 0.25, and b* of 1.57 to 2.24. In addition, the recycled bisphenol A monomer compositions obtained in Examples 1 to 3 showed a high BPA yield of 68% to 73%. In addition, the recycled bisphenol A monomer composition obtained in Examples 1 to 3 had an impurity ratio as low as 0.3% to 0.9%. On the other hand, the recycled bisphenol A monomer composition obtained in Comparative Example 1 had a color coordinate of L* of 96.0 and a* of 96.0. 0.34, b* showed 2.49, indicating poor optical properties compared to the examples. In addition, the recycled bisphenol A monomer composition obtained in Comparative Example 1 had a BPA yield of 65%, which was lower than that of Example.

Claims (19)

Contains an aromatic diol compound,
The monomer composition for synthesizing recycled plastic has an impurity ratio of 1.2% or less according to the following formula 1,
The aromatic diol compound yield according to Formula 2 is greater than 65%,
Characterized in that the monomer composition for synthesizing recycled plastics is recovered from a polycarbonate-based resin, a monomer composition for synthesizing recycled plastics:
[Equation 1]
Impurity ratio = {(total peak area on liquid chromatography - bisphenol A peak area on liquid chromatography) / total peak area on liquid chromatography} X 100,
[Equation 2]
Yield (%) = W ₁ /W ₀
In Equation 2, W ₀ is the mass of the aromatic diol compound obtained upon 100% decomposition of the polycarbonate-based resin, and W ₁ is the mass of the aromatic diol compound actually obtained.
According to claim 1,
The monomer composition for synthesizing recycled plastics has a color coordinate L* of 94 or more, the monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing recycled plastics has a color coordinate a* of 0.5 or less, the monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing recycled plastics has a color coordinate b* of 0 to 4.2, the monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing recycled plastics has an aromatic diol compound purity of 99% or more, the monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing recycled plastics is characterized in that diethyl carbonate is obtained as a by-product, and the diethyl carbonate is recovered from a polycarbonate-based resin.
Depolymerizing the polycarbonate-based resin;
adding a base so that the pH of the depolymerization reaction product is 12 or higher;
separating the carbonate precursor from the depolymerization reaction product by adding water after the addition of the base; and
A method for preparing a monomer composition for synthesizing recycled plastic, comprising: adding an acid so that the pH of the depolymerization reaction product from which the carbonate precursor is separated becomes 4 or less.
According to claim 7,
In the step of adding a base so that the pH of the depolymerization reaction product is 12 or higher,
A method for preparing a monomer composition for synthesizing recycled plastics, wherein the aromatic diol compound included in the depolymerization reaction product is converted into a salt of the aromatic diol compound.
According to claim 7,
In the step of separating the carbonate precursor from the depolymerization reaction product by adding water after the addition of the base,
A method for preparing a monomer composition for synthesizing recycled plastics, wherein an aqueous layer containing a salt of an aromatic diol compound and an organic solvent layer containing diethyl carbonate are separated.
According to claim 7,
In the step of adding an acid so that the pH of the depolymerization product from which the carbonate precursor is separated becomes 4 or less,
A method for preparing a monomer composition for synthesizing recycled plastics, wherein a salt of an aromatic diol compound included in the depolymerization reaction product is converted to an aromatic diol compound.
According to claim 7,
The depolymerization reaction of the polycarbonate-based resin,
A method for producing a monomer composition for synthesizing recycled plastics, characterized in that the process is performed in a solvent containing ethanol.
According to claim 11,
The content of the ethanol is 10 to 15 moles relative to 1 mole of the polycarbonate-based resin, a method for producing a monomer composition for synthesizing recycled plastic.
According to claim 7,
The depolymerization reaction of the polycarbonate-based resin,
A method for producing a monomer composition for synthesizing recycled plastics, characterized in that the reaction is performed with a base in an amount of 0.5 mol or less relative to 1 mol of polycarbonate-based resin.
According to claim 7,
After the step of adding an acid so that the pH of the depolymerization product from which the carbonate precursor is separated becomes 4 or less,
A method for producing a monomer composition for synthesizing recycled plastic, further comprising a step of purifying the depolymerization reaction product from which the carbonate precursor is separated.
According to claim 14,
In the step of purifying the depolymerization reaction product from which the carbonate precursor is separated,
A method for preparing a monomer composition for synthesizing recycled plastics, comprising recrystallizing a depolymerization product from which the carbonate precursor is separated.
According to claim 14,
In the step of purifying the depolymerization reaction product from which the carbonate precursor is separated,
A method for producing a monomer composition for synthesizing recycled plastic, comprising a step of adsorption and purification of the depolymerization reaction product from which the carbonate precursor is separated.
According to claim 14,
In the step of purifying the depolymerization reaction product from which the carbonate precursor is separated,
A method for producing a monomer composition for synthesizing recycled plastic, comprising a step of washing the depolymerization reaction product from which the carbonate precursor is separated.
A recycled plastic comprising a reaction product of the monomer composition for synthesizing recycled plastic according to claim 1 and a comonomer.
A molded article comprising the recycled plastic of claim 18.