KR20230052755A - Monomer composition for synthesising recycled plastic, prepration method thereof, and recycled plastic, molded product using the same - Google Patents

Abstract

The present invention is to provide a monomer composition for synthesizing recycled plastic, which can secure an aromatic diol compound with improved optical properties recovered through recycling by chemical decomposition of a polycarbonate-based resin in high yield. The present invention relates to a monomer composition for synthesizing recycled plastic, which comprises an aromatic diol compound, has color coordinate b* of 0.1 to 1 and an aromatic diol compound yield of greater than 75 %, and is recovered from a polycarbonate-based resin, a preparation method thereof, and recycled plastic and molded products using the same.

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 article.

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.

The present invention is to provide a monomer composition for synthesizing recycled plastics capable of securing an aromatic diol compound having improved optical properties recovered through recycling of polycarbonate-based resin through chemical decomposition in high yield.

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, the monomer composition for synthesizing recycled plastics includes an aromatic diol compound, has a color coordinate of b* of 0.1 to 1, and yields more than 75% of the aromatic diol compound according to Formula 1 below A monomer composition for synthesizing recycled plastics, characterized in that recovered from polycarbonate-based resins, is provided.

[Equation 1]

Yield (%) = W ₁ /W ₀

In Equation 1, W ₀ is the mass of the aromatic diol compound obtained upon 100% decomposition, 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 an acid so that the pH of the depolymerization reaction product is 2 to 8; After adding the acid, removing impurities; and separating the carbonate precursor from the depolymerization reaction product.

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 aromatic diol compound is included, the color coordinate b* is 0.1 to 1, the yield of the aromatic diol compound according to Formula 1 is greater than 75%, and the monomer composition for synthesizing recycled plastic is polycarbonate-based A monomer composition for synthesizing recycled plastics, characterized in that it is recovered from the resin, can be provided.

The present inventors have found that the monomer composition for synthesizing recycled plastics according to an embodiment of the present invention has a low color coordinate b* value at a color level equivalent to that of reagents commercially sold or used for PC polymerization, even though it is recovered through recycling by chemical decomposition of polycarbonate-based resins. It was confirmed through experiments that an aromatic diol compound that satisfies can be obtained in high yield, and the present invention was completed.

Specifically, in the case of an aromatic diol compound recovered through recycling by chemical decomposition of a conventional polycarbonate-based resin, the color coordinate b* value is relatively high in the range of more than 1 and less than 4, and the color is too biased toward yellow, resulting in poor color characteristics. The aromatic diol compound recovered in the present invention can secure a color coordinate b* value as low as 0.1 to 1, or 0.1 to 0.5, or 0.2 to 0.5, or 0.21 to 0.43.

In the case of commercially used polycarbonate, transparency and color specifications are important due to the nature of the use, and the color of polycarbonate depends on the color of the aromatic diol compound (eg, bisphenol A (BPA)) as a raw material. In the case of recycled BPA obtained through chemical decomposition from polycarbonate, the color specification of recycled BPA was lowered due to side reaction products that were not removed, and the color of polycarbonate polymerized using it was also affected. In particular, the color coordinate b* value of recycled BPA is important.

In addition, as the content of impurities other than the aromatic diol compound, which is the main recovery target, is extremely reduced, it was confirmed through experiments that excellent physical properties can be realized when synthesizing a polycarbonate-based resin using this, 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 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 according to one 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 0.1 to 1, or 0.1 to 0.5, or 0.2 to 0.5, or 0.21 to 0.43. In addition, the monomer composition for synthesizing recycled plastic according to one embodiment may have a color coordinate L* of 98 or more, or 100 or less, or 98 to 100, or 98.12 to 98.91. In addition, the monomer composition for synthesizing recycled plastic according to one embodiment may have a color coordinate of a* of 0 or less, or -0.2 or more, or -0.2 to 0, or -0.15 to -0.01.

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 whether the color with the corresponding color coordinates is biased toward pure red or pure green, and the b* value indicates whether the color with the corresponding color coordinates is pure yellow or 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 toward 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 according to one embodiment is excessively increased to more than 0 or the color coordinate L* value is excessively decreased to less than 98, the color characteristics of the monomer composition for synthesizing recycled plastics according to 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 1, the color of the monomer composition for synthesizing recycled plastics according to one embodiment is excessively 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 0.1, 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.

Meanwhile, the monomer composition for synthesizing recycled plastic according to one embodiment may have a purity of 98% or more, or 100% or less, or 98% to 100% of the aromatic diol compound.

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 the embodiment, the monomer composition for synthesizing recycled plastics of the embodiment is 1w% Acetonitrile (ACN) at atmospheric pressure and 20 to 30 ° C. 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 98% 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 other than aromatic diol compounds, which are the main recovery target materials of the present invention, and their specific types are not greatly limited, but sodium salts are exemplified.

In particular, by adjusting the pH of the depolymerization reaction product to be 2 to 8 according to the method for preparing a monomer composition for synthesizing recycled plastics described later, an aromatic diol compound, which is a main material to be recovered, may exist in the organic phase, and thus water-soluble impurities can be easily removed by separating into the water layer, and acidic organic impurities having stronger acidity than the aromatic diol compound can be further removed.

Specifically, the monomer composition for synthesizing recycled plastics may have a weight ratio of sodium salt impurities measured by ion chromatography less than 10 μg relative to 1 g of the monomer composition for synthesizing recycled plastics.

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

As such, in the monomer composition for synthesizing recycled plastics of one embodiment, the weight ratio of sodium salt impurities other than the aromatic diol compound, which is the main recovery target material, is extremely reduced to less than 10 ug compared to 1 g of the monomer composition for synthesizing recycled plastics, using this When synthesizing polycarbonate-based resin, it is possible to realize excellent physical properties.

Meanwhile, the monomer composition for synthesizing recycled plastic according to one embodiment has an aromatic diol compound yield of greater than 75%, or greater than or equal to 76%, or greater than or equal to 77%, or greater than or equal to 100%, or greater than 75% and less than or equal to 100%, or 77% to 100%. %, or 78% to 100%. The increase in the yield of the aromatic diol compound to more than 75% 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 the embodiment is not particularly limited, and can be calculated through Equation 1 below.

[Equation 1]

Yield (%) = W ₁ /W ₀

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

For the mass of the aromatic diol compound in Formula 1, 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 75%, 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 an acid so that the pH of the depolymerization reaction product is 2 to 8; After adding the acid, removing impurities; and separating the carbonate precursor from the depolymerization reaction product.

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 inventors of the present invention adjust the pH of the depolymerized polycarbonate-based resin to chemically synthesize the polycarbonate-based resin. Although recovered through recycling by decomposition, it was confirmed through experimentation that aromatic diol compounds satisfying a low color coordinate b* value with a color level equivalent to that of reagents commercially sold or used for PC polymerization can be obtained in high yield and invented. has been completed.

In particular, by adjusting the pH of the depolymerization reaction product to be 2 to 8, the aromatic diol compound, which is the main material to be recovered, can exist in the organic phase, and thus, water-soluble impurities can be separated into the water layer and easily removed. Acidic organic impurities having stronger acidity than the diol compound can be further removed.

Therefore, as the content of impurities other than the aromatic diol compound, which is the main recovery target, is extremely reduced, it was confirmed through experiments that excellent physical properties can be realized when synthesizing a polycarbonate-based resin using this, and the invention was completed.

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.

Meanwhile, during the depolymerization reaction of the polycarbonate-based resin, an antioxidant may be added to the reaction solution. As the antioxidant is added, the aromatic diol compound recovered through recycling by chemical decomposition of the polycarbonate-based resin can satisfy a low color coordinate b* value of a color level equivalent to that of commercially sold or used reagents for PC polymerization. there is.

Specific examples of the antioxidant are not particularly limited, and various antioxidants that have been widely used in the prior art can be applied without limitation. However, for example, sodium hyposulfite, sodium sulfite, erythorbic acid, dibutylhydroxytoluene, butylhydroxyanisole, α-tocopherol, tocopherol acetate, L-ascorbic acid and its salts, L-ascorbic acid palmitate, L -ascorbic acid stearate, triamyl gallate, propyl gallate or ethylenediamine disodium tetraacetate (EDTA), sodium pyrophosphate, sodium metaphosphate, or a mixture of two or more thereof.

The specific input amount of the antioxidant is also not particularly limited, but, for example, within the range of 0.1% to 5% by weight, or 0.1% to 1% by weight based on the total weight of the reaction solution, the physical properties of the monomer composition for synthesizing recycled plastics It can be injected at a level that does not affect it.

In addition, during the depolymerization of the polycarbonate-based resin, the depolymerization may be performed under a nitrogen atmosphere.

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, a base, and an antioxidant. In the first and second steps, the contents of ethanol, organic solvent, base, antioxidant, 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 an acid so that the pH of the depolymerization reaction product is 2 to 8. A strong acid may be used as the acid, and examples thereof include hydrochloric acid (HCl).

In the step of adding an acid so that the pH of the depolymerization reaction product is 2 to 8, a salt of an aromatic diol compound included in the depolymerization reaction product may be converted into an aromatic diol compound. As the depolymerization reaction proceeds under basic conditions, the resulting aromatic diol compound reacts with a base to exist in the form of a salt and thus has hydrophilicity. Therefore, by adding an acid, the salt of the aromatic diol compound included in the depolymerization reaction product can be converted into an aromatic diol compound to induce hydrophobicity.

Accordingly, in the step of removing impurities by adding water after adding the acid, which will be described later, a layer divided into a water layer containing impurities and an organic solvent layer containing an aromatic diol compound and a carbonate precursor may be formed. Since the aromatic diol compound and the carbonate precursor have hydrophobicity, they may be included in the organic solvent layer among water and the organic solvent, and various water-soluble impurities may be included in the water layer. Accordingly, it is possible to easily separate the aromatic diol compound, which is the main product, from impurities with only a simple process of changing the pH.

Meanwhile, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may further include adding water in the step of adding an acid so that the pH of the depolymerization reaction product is 2 to 8. Through this, in the impurity removal step to be described later, a layer divided into a water layer containing impurities and an organic solvent layer containing an aromatic diol compound and a carbonate precursor may be formed.

The order of adding acid and adding water is not particularly limited, and water may be added after acid is added, acid may be added after water is added, or both water and acid may be added simultaneously.

Meanwhile, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may include removing impurities after adding the acid. Accordingly, the impurity is a material having hydrophilicity, and may include, for example, a salt compound, an ionic compound, an acid compound, and the like.

As described above, after the step of adding an acid so that the pH of the depolymerization reaction product is 2 to 8, the step of removing impurities from the depolymerization reaction product after the addition of the acid proceeds, so that the depolymerization reaction product becomes an impurity. A layer divided into a water layer containing this and an organic solvent layer containing an aromatic diol compound and a carbonate precursor may be formed, and the water layer containing impurities may be separated and removed therefrom.

In the step of removing impurities from the depolymerization reaction product after the addition of the acid, impurities included in the water layer may be removed by separating the water layer from the organic layer. Specific separation conditions for separating the water layer from the organic 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 drain device may be used.

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

In the step of separating the carbonate precursor from the depolymerization reaction product, a step of distilling the depolymerization reaction product under reduced pressure may be included. Examples of the vacuum distillation conditions are not particularly limited, but as a specific example, after pressurizing the product of the depolymerization reaction of the polycarbonate-based resin at a pressure of 200 mbar to 300 mbar and a temperature condition of 20 ° C. to 30 ° C., 10 Low-temperature distillation may be performed under reduced pressure at a pressure of mbar to 50 mbar and a temperature of 20 °C to 30 °C.

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, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may further include a step of purifying the depolymerization product from which the carbonate precursor is separated after the step of separating the carbonate precursor from the depolymerization product.

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 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 in the step of washing with a solvent at a temperature of 40 ° C or more and 80 ° C or less and the temperature in the step 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 .

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 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 carbonization at about 500 ° C and activated carbon at about 900 ° C. The example is not greatly limited, but for example, the raw material 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 capable of securing an aromatic diol compound having improved optical properties in high yield, a manufacturing method thereof, recycled plastic using the same, and a molded product can be provided.

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. , As an antioxidant, sodium hydrosulfite was added in an amount of 0.7% by weight relative to the total solution, and the atmosphere in the system was substituted with nitrogen, and stirred at 60 ° C. for 6 hours in an inactive state to proceed with PC depolymerization.

(2. pH Adjustment) The product of the depolymerization reaction was cooled to 30° C. or less, and the pH was adjusted to 8 by adding 10% hydrochloric acid (HCl) and water to the bisphenol A product.

After (3. Layer Separation), with the water layer and the methylene chloride (MC) layer formed, the organic layer located at the bottom was recovered using a drain device at the bottom of the reactor, and the water layer located at the top was discharged and discarded.

(4. Distillation) After that, diethyl carbonate (DEC), a by-product, was classified and recovered through low-temperature distillation of the recovered methylene chloride (MC) layer under reduced pressure from 250 mbar, 20 to 30 °C to 30 mbar, 30 °C.

After (5. Purification Step-Filtration), the residue from which diethyl carbonate (DEC) was removed was first washed at 20 to 30 ° C using methylene chloride (MC) twice the mass of PC used, followed by vacuum filtration did The filtrate was washed a second time at a temperature of 50° C. with water twice the mass of PC used.

(6-1. Additional purification step - redissolution step) After that, bisphenol A was added to 16.6 mol of ethanol and dissolved again.

After (6-2. Additional purification step-adsorption step), activated lignite was added as an adsorbent at a ratio of 50% by weight to waste polycarbonate, purified through adsorption for 3 hours, and then activated charcoal was removed through filtration.

After (6-3. 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.

(7. 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 40° C. convection oven.

Example 2

A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that the pH was adjusted to 7 instead of 8 in (2. pH adjustment) of Example 1.

Example 3

A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that the pH was adjusted to 5 instead of 8 in (2. pH adjustment) of Example 1.

Example 4

A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that the pH was adjusted to 2 instead of 8 in (2. pH adjustment) of Example 1.

Comparative Example 1

A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that (2. pH adjustment) and (3. Layer separation) of Example 1 were not performed.

Comparative Example 2

Recycled bisphenol A in the same manner as in Example 1, except that 10% hydrochloric acid (HCl) was not added in (2. pH adjustment) in Example 1, and only water was added so that the pH exceeded 10. A monomer composition was prepared.

<Experimental example>

With respect to the recycled bisphenol A monomer compositions 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 1 below.

[Equation 1]

Yield (%) = W ₁ /W ₀

In Equation 1, 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. Sodium salt impurity content

1 ml of the recycled bisphenol A monomer composition was taken as a sample and subjected to ion chromatography (IC) analysis under the following conditions, and the weight ratio of sodium salt impurities contained therein based on 1 g of the sample (unit: μg/g) was measured.

<Ion chromatography (IC) 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

Experimental example measurement result division water(%) L* a* b* BPA yield (%) Sodium salt (μg/g) Example 1 99.82 98.91 -0.05 0.42 79.1 <10 Example 2 99.92 98.71 -0.01 0.43 82.2 <10 Example 3 99.71 98.12 -0.15 0.22 82.1 <10 Example 4 99.29 98.19 -0.03 0.21 83.0 <10 Comparative Example 1 96.82 97.82 0.31 1.62 69.1 100 Comparative Example 2 97.14 97.12 0.06 1.16 65.1 55

As shown in Table 1, the recycled bisphenol A monomer compositions obtained in Examples 1 to 4 exhibited a high purity of 99.29% to 99.92%. In addition, the recycled bisphenol A monomer compositions obtained in Examples 1 to 4 exhibited excellent optical properties with color coordinates L* of 98.12 to 98.91, a* of -0.15 to -0.01, and b* of 0.21 to 0.43. In addition, the recycled bisphenol A monomer compositions obtained in Examples 1 to 4 showed a high BPA yield of 79.1% to 83%. In addition, the recycled bisphenol A monomer composition obtained in Examples 1 to 4 had an impurity content as low as less than 10 μg/g. On the other hand, the recycled bisphenol A monomer composition obtained in Comparative Examples 1 to 2 had a purity of 96.82% to 97.14%. It was lower than that of the Example. In addition, the recycled bisphenol A monomer compositions obtained in Comparative Examples 1 and 2 showed color coordinates L* of 97.12 to 97.82, a* of 0.06 to 0.31, and b* of 1.16 to 1.62, indicating poor optical properties compared to the examples. In addition, the recycled bisphenol A monomer compositions obtained in Comparative Examples 1 and 2 had a BPA yield of 65.1% to 69.1%, which was lower than that of the examples.

Claims (20)

Contains an aromatic diol compound,
The color coordinate b* is 0.1 to 1,
The aromatic diol compound yield according to Formula 1 is greater than 75%,
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]
Yield (%) = W ₁ /W ₀
In Equation 1, W ₀ is the mass of the aromatic diol compound obtained upon 100% decomposition, 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 98 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 or less, 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 98% or more, the monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing recycled plastics has a weight ratio of sodium salt impurities measured using ion chromatography of less than 10 ug relative to 1 g of 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 an acid so that the pH of the depolymerization reaction product is 2 to 8;
After adding the acid, removing impurities; and
A method for producing a monomer composition for synthesizing recycled plastic, comprising: separating a carbonate precursor from the depolymerization reaction product.
According to claim 7,
In the step of adding an acid so that the pH of the depolymerization reaction product is 2 to 8,
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,
After adding the acid, in the step of removing impurities,
A method for preparing a monomer composition for synthesizing recycled plastics, wherein a water layer containing impurities and an organic solvent layer containing an aromatic diol compound and a carbonate precursor are separated.
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 10,
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 proceeds with a base in an amount of 0.5 mol or less relative to 1 mol of polycarbonate-based resin.
According to claim 7,
During the depolymerization reaction of the polycarbonate-based resin,
A method for producing a monomer composition for synthesizing recycled plastic, characterized in that an antioxidant is added to the reaction solution.
According to claim 7,
In the step of separating the carbonate precursor from the depolymerization reaction product,
A method for producing a monomer composition for synthesizing recycled plastic, comprising distilling the depolymerization reaction product under reduced pressure.
According to claim 7,
After the step of separating the carbonate precursor from the depolymerization reaction product,
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 15,
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.
According to claim 15,
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 15,
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.
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 19 .