KR20230083783A - 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, a preparation method thereof, and recycled plastics and molded products using the same. The monomer composition for synthesizing recycled plastics includes an aromatic diol compound, the weight ratio of chromanic impurities measured using gas chromatography mass spectrometry (GC/MS) is less than 110 ug compared to 1 g of the monomer composition for synthesizing recycled plastics, and the monomer composition for synthesizing recycled plastics is recovered from a polycarbonate-based resin.

Description

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

The present invention is obtained through a recycling process by chemical decomposition of polycarbonate-based resin having high efficiency, and a monomer composition for synthesizing recycled plastic in which impurities derived from aromatic diol compounds are minimized during chemical decomposition of polycarbonate-based resin, manufacturing thereof It relates to a method, a 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 plastic obtained through a recycling process by chemical decomposition of polycarbonate-based resin having high efficiency and minimizing impurities derived from aromatic diol compounds during chemical decomposition of polycarbonate-based resin. it is for

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 weight ratio of chroman-based impurities including an aromatic diol compound and measured using gas chromatography mass spectrometry (GC / MS) is compared to 1 g of the monomer composition for synthesizing recycled plastics. Less than 110 ug, and the monomer composition for synthesizing recycled plastics provides a monomer composition for synthesizing recycled plastics, characterized in that recovered from a polycarbonate-based resin.

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 greater than 4 and less than 9; After adding the acid, removing chroman-based impurities by adding water; 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 weight ratio of chroman-based impurities including an aromatic diol compound and measured using gas chromatography mass spectrometry (GC/MS) is less than 110 ug relative to 1 g of the monomer composition for synthesizing recycled plastics. And, the monomer composition for synthesizing recycled plastics may be provided with a monomer composition for synthesizing recycled plastics, characterized in that recovered from polycarbonate-based resin.

The inventors of the present invention have found that the monomer composition for synthesizing recycled plastics of one embodiment is recovered through recycling by chemical decomposition of polycarbonate-based resins, but the content of impurities other than aromatic diol compounds, particularly chroman-based impurities, which are the main target of recovery, is extremely reduced. , Using this, it was confirmed through experiments that excellent physical properties can be realized when synthesizing polycarbonate-based resins, and the invention was completed.

When polycarbonate is depolymerized using alcohol under a conventional base catalyst, the pH is adjusted to a strong acidity level of 1 to 2 using an aqueous solution of strong acid before the purification process, and the water layer among the separated water layer and organic layer is discarded, and the organic layer is purified and adsorbed. have been applied to However, in this case, the process inefficiency was large in that the water layer had to be neutralized again to be disposed of, and the aromatic diol compound (bisphenol A), which is the main recovery target, was decomposed in strongly acidic conditions to produce impurities that cause coloration. The color of the monomer composition for synthesizing recycled plastic according to the embodiment is too biased toward yellow, and thus has poor color characteristics.

Therefore, in the present invention, after discarding the water layer of the layer-separated water layer and the organic layer under the conditions of pH greater than 4 and less than 9, more specifically, pH 6 to 8 corresponding to neutrality, the organic layer is applied to the purification and adsorption process, thereby performing an additional neutralization process. It does not need to be rough, so the efficiency of the process is increased, and the aromatic diol compound (bisphenol A) is decomposed to suppress the generation of impurities that cause a color phenomenon.

In addition, the monomer composition for synthesizing recycled plastics (composition 1) of one embodiment, together with diethyl carbonate, wherein the diethyl carbonate is recovered from the polycarbonate-based resin, characterized in that the monomer composition for synthesizing recycled plastics (Second composition) 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)cyclohexane (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 may further include impurities other than the aromatic diol compound. The impurities refer to all substances other than the aromatic diol compound, which is the main recovery target material of the present invention, and their specific types are not greatly limited, but examples thereof include chroman-based impurities and aromatic monool impurities.

In particular, according to the method for preparing a monomer composition for synthesizing recycled plastics described later, the pH of the depolymerization reaction product is adjusted to be greater than 4 and less than 9, more specifically, pH 6 to 8 corresponding to neutrality, so that the aromatic diol compound, the main material to be recovered, is removed from the organic phase. Therefore, water-soluble impurities can be easily removed by separating them 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 has a weight ratio of chroman-based impurities measured using gas chromatography mass spectrometry (GC/MS) of less than 110 ug or 100 ug relative to 1 g of the monomer composition for synthesizing recycled plastics. or less than 90 ug, or less than 80 ug, or less than 70 ug, or less than 60 ug, or less than 50 ug, or less than 40 ug, or less than 30 ug, or less than 30 ug, or less than 20 ug, or 10 ug less than, or less than 5 ug, or greater than or equal to 0.1 ug, or greater than or equal to 0.1 ug and less than 110 ug, or greater than or equal to 0.1 ug and less than 100 ug, or greater than or equal to 0.1 ug and less than 90 ug, or greater than or equal to 0.1 ug and less than 80 ug, or greater than or equal to 0.1 ug and less than 70 ug less than 0.1 ug and less than 60 ug, or greater than 0.1 ug and less than 50 ug, or greater than 0.1 ug and less than 40 ug, or greater than 0.1 ug and less than 30 ug, or greater than 0.1 ug and less than 30 ug, or greater than 0.1 ug and less than 20 ug, or It may be 0.1 ug or more and less than 10 ug, or 0.1 ug or more and less than 50 ug.

An example of gas chromatography mass spectrometry for measuring the weight ratio of the chroman-based impurities in the monomer composition for synthesizing recycled plastics according to one embodiment is not particularly limited. For example, the monomer composition for synthesizing recycled plastics according to one embodiment A sample was taken and subjected to quantitative analysis through GC/MS equipment, and the weight ratio (μg/g) of chroman-based impurities contained in the sample was measured based on 1 g of the sample. More specifically, the chroman-based impurity may be 4-(2,2,4-trimethyl-chroman-4-yl)-phenol.

As a more specific example, the concentration of the sample of the monomer composition for synthesizing recycled plastic may be 1 mg/ml to 20 mg/ml, or 5 mg/ml to 15 mg/ml, or 8 mg/ml to 12 mg/ml.

In addition, examples of GC/MS equipment and operating conditions are not particularly limited, and various known GC/MS equipment and operating conditions can be applied without limitation. However, for example, ①Column: HP-5MS (L: 30m, ID: 0.25mm, film: 0.25μm), ② Injection volume: 0.2μl, ③ Inlet, Temp.: 300 ℃, Pressure: 7.07psi, Total flow : 24ml/min, Split flow: 20ml/min, spilt ratio: 20:1, ④ Column flow: 1ml/min, ⑤ Oven temp.: 50℃/5min-10℃/min-320℃/10min (Total 42min) , ⑥ Detector Temp.: 300℃, H ₂ : 35ml/min, Air: 300ml/min, He: 30ml/min, ⑦ GC Model: Agilent 7890. It can proceed under normal laboratory conditions (eg, normal pressure, room temperature).

As such, in the monomer composition for synthesizing recycled plastics of the embodiment, the weight ratio of chroman-based impurities other than the aromatic diol compound, which is the main recovery target material, is extremely reduced to less than 110 ug compared to 1 g of the monomer composition for synthesizing recycled plastics. It is possible to realize excellent physical properties when synthesizing a polycarbonate-based resin.

On the other hand, when the weight ratio of the chroman-based impurities measured by gas chromatography mass spectrometry is excessively increased to 110 μg or more relative to 1 g of the monomer composition for synthesizing recycled plastics, the monomer composition for synthesizing recycled plastics according to one embodiment When synthesizing the used recycled plastic, the polymerization time is extended, resulting in a decrease in polymerization production efficiency and poor color quality such as an increase in the yellow index.

In addition, the monomer composition for synthesizing recycled plastics has a weight ratio of aromatic monool impurities measured by gas chromatography mass spectrometry (GC/MS) of less than 260 ug or less than 200 ug relative to 1 g of the monomer composition for synthesizing recycled plastics. , or 180 ug or less, or 150 ug or less, or 100 ug or less, or 90 ug or less, or 80 ug or less, or 70 ug or less, or 60 ug or less, or 50 ug or less, 0.1 ug or more, or 0.1 ug or more 260 Less than ug, or 0.1 ug to 200 ug, or 0.1 ug to 180 ug, or 0.1 ug to 150 ug, or 0.1 ug to 100 ug, or 0.1 ug to 90 ug, or 0.1 ug to 80 ug, or 0.1 ug to 70 ug, or 0.1 ug to 60 ug, or 0.1 ug to 50 ug, or greater than 50 ug and less than or equal to 70 ug, greater than 70 ug and less than or equal to 90 ug.

An example of gas chromatography mass spectrometry for measuring the weight ratio of the aromatic monool impurity in the monomer composition for synthesizing recycled plastics of one embodiment is not particularly limited. For example, the monomer composition for synthesizing recycled plastics of one embodiment A sample was taken and subjected to quantitative analysis through GC/MS equipment, and the aromatic monool impurity weight ratio (μg/g) contained in the sample was measured based on 1 g of the sample. More specifically, the aromatic monool impurity may be 4-isopropenyl phenol.

As a more specific example, the concentration of the sample of the monomer composition for synthesizing recycled plastic may be 1 mg/ml to 20 mg/ml, or 5 mg/ml to 15 mg/ml, or 8 mg/ml to 12 mg/ml.

In addition, examples of GC/MS equipment and operating conditions are not particularly limited, and various known GC/MS equipment and operating conditions can be applied without limitation. However, for example, ①Column: HP-5MS (L: 30m, ID: 0.25mm, film: 0.25μm), ② Injection volume: 0.2μl, ③ Inlet, Temp.: 300 ℃, Pressure: 7.07psi, Total flow : 24ml/min, Split flow: 20ml/min, spilt ratio: 20:1, ④ Column flow: 1ml/min, ⑤ Oven temp.: 50℃/5min-10℃/min-320℃/10min (Total 42min) , ⑥ Detector Temp.: 300℃, H ₂ : 35ml/min, Air: 300ml/min, He: 30ml/min, ⑦ GC Model: Agilent 7890. It can proceed under normal laboratory conditions (eg, normal pressure, room temperature).

As such, in the monomer composition for synthesizing recycled plastics of the embodiment, the weight ratio of aromatic monool impurities other than the aromatic diol compound, which is the main recovery target material, is extremely reduced to less than 260 ug compared to 1 g of the monomer composition for synthesizing recycled plastics. It is possible to realize excellent physical properties when synthesizing a polycarbonate-based resin.

On the other hand, when the weight ratio of the aromatic monool impurity measured by gas chromatography mass spectrometry is excessively increased to 260 μg or more relative to 1 g of the monomer composition for synthesizing recycled plastics, the monomer composition for synthesizing recycled plastics of one embodiment When synthesizing recycled plastics using , the polymerization time is extended, resulting in a decrease in polymerization production efficiency and poor color quality such as an increase in yellowness index.

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 greater than 4 and less than 9; After adding the acid, removing chroman-based impurities; and separating the carbonate precursor from the depolymerization reaction product.

As in the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment, the pH of the depolymerization reaction product is adjusted to be greater than 4 and less than 9 so that the aromatic diol compound, which is the main material to be recovered, may exist in the organic phase, and thus, water-soluble Chroman-based impurities can be separated into a water layer to be easily removed, and acidic organic impurities having stronger acidity than aromatic diol compounds can be further removed.

Therefore, as the content of chroman-based 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 product is greater than 4 and less than 9. A strong acid may be used as the acid, and examples thereof include hydrochloric acid (HCl).

The pH of the depolymerization product is greater than 4 and less than 9, or greater than 4, or greater than 4.5, or greater than 5, or greater than 5.5, or greater than 6, or greater than 6.5, or greater than 7, or greater than 7.5, or less than 9, or 8.5 less than, or less than 8, or less than 7.5, or less than 7, or less than 6.5, or 4.5 to 8.5, or 5 to 8.5, or 5.5 to 8.5, or 6 to 8.5, or 6.5 to 8.5, or 7 to 8.5, or 7.5 to 8.5, or 8 to 8.5, or 4.5 to 8, or 5 to 8, or 5.5 to 8, or 6 to 8, or 6.5 to 8, or 7 to 8, or 7.5 to 8, or 4.5 to 7.5, or 5 to 7.5, or 5.5 to 7.5, or 6 to 7.5, or 6.5 to 7.5, or 7 to 7.5, or 4.5 to 7, or 5 to 7, or 5.5 to 7, or 6 to 7, or 6.5 to 7, or 4.5 to 6.5, or 5 to 6.5, or 5.5 to 6.5, or 6 to 6.5, or 4.5 to 6, or 5 to 6, or 5.5 to 6, in the step of adding an acid to the aromatic diol contained in the depolymerization reaction product A salt of the compound may be converted to 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 chroman-based impurities after the acid addition described later, a layer divided into a water layer containing chroman-based 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 an organic solvent layer among water and an organic solvent, and water-soluble chroman-based 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 the chroman-based impurity by only a simple process of changing the pH.

On the other hand, if the pH of the depolymerization reaction product is excessively reduced to less than 7 in the step of adding the acid, the process inefficiency is large in that the strongly acidic water layer must be neutralized again and disposed of, and the main recovery under strongly acidic conditions is necessary. The target aromatic diol compound (bisphenol A) is decomposed to produce impurities that cause a colored phenomenon, so that the color of the monomer composition for synthesizing recycled plastic according to one embodiment is too biased toward yellow, resulting in poor color characteristics.

In addition, if the step of adding an acid is not performed so that the pH of the depolymerization reaction product is greater than 4 and less than 9, and the basic condition is continuously maintained, the salt of the water-soluble aromatic diol compound moves along with impurities to the water layer, and the organic layer Separation of the impurities and the aromatic diol compound is not sufficient only through the layer separation between the water layer and the water layer. Therefore, since an additional purification process for separating only the aromatic diol compound must be performed, a problem in that the efficiency of the process for securing the recycled aromatic diol compound may decrease.

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 greater than 4 and less than 9. Through this, in a chroman-based impurity removal step to be described later, a layer divided into a water layer containing chroman-based 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 chroman-based impurities after adding the acid. Accordingly, the chroman-based impurity is a material having hydrophilicity, and may include, for example, 4-(2,2,4-trimethyl-chroman-4-yl)-phenol.

As described above, after the step of adding an acid so that the pH of the depolymerization reaction product is greater than 4 and less than 9, the step of removing chroman-based impurities from the depolymerization reaction product proceeds after the addition of the acid, and the depolymerization The reaction product forms a layer divided into a water layer containing chroman-based impurities and an organic solvent layer containing an aromatic diol compound and a carbonate precursor, from which the water layer containing chroman-based impurities can be separated and removed.

After adding the acid, in the step of removing chroman-based impurities from the depolymerization reaction product, the water layer may be separated from the organic layer to remove chroman-based impurities included in the water 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.

In addition, in the step of removing chroman-based impurities after the addition of the acid, aromatic monool impurities may be removed. The aromatic monool impurities may also be included in the water layer and separated and removed in the same way as chroman-based impurities. The aromatic monool impurity may include 4-isopropenyl phenol.

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 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 temperature 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 .

If the difference between the temperature in the step of washing with a solvent at a temperature of 40 ° C. or more and less than or equal to 80 ° C. 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 excessively reduced to less than 20 ° C., impurities are removed. Hard enough to remove.

If 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 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 obtained through a recycling process by chemical decomposition of polycarbonate-based resin having high efficiency and minimizing impurities derived from aromatic diol compounds during chemical decomposition of polycarbonate-based resin, A manufacturing method thereof, recycled plastic using the same, and molded articles may 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, Comparative Examples and Reference 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 then 10% hydrochloric acid (HCl) and water were added to the product of the depolymerization reaction to adjust the pH to 8.

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 using twice the amount of water compared to the PC mass 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.

After (7. Drying step), 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

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 7.5 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 6 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 the pH was adjusted to 2 instead of 8 in (2. pH adjustment) of Example 1.

Comparative 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 4 instead of 8 in (2. pH adjustment) of Example 1.

Reference example 1

A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that the pH was adjusted to 9 instead of 8 in (2. pH adjustment) of Example 1.

Reference 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 10 instead of 8 in (2. pH adjustment) of Example 1.

<Experimental example>

The physical properties of the recycled bisphenol A monomer compositions obtained in Examples, Comparative Examples, and Reference Examples were measured in the following manner, and the results are shown in Table 1.

1. Impurity content

(1) Chroman impurities

The recycled bisphenol A monomer composition was taken as a sample, diluted with methanol to a concentration of 10 mg/ml, and gas chromatography mass spectrometry (GC-MS) was performed using GC/MS equipment under the following conditions, based on 1 g of the sample The weight ratio (unit: μg/g) of chroman (4-(2,2,4-trimethyl-chroman-4-yl)-phenol) impurity contained therein was measured.

<Gas chromatography (GC) conditions>

①Column: HP-5MS (L:30m, ID:0.25mm, film:0.25μm)

② Injection volume: 0.2 μl

③ Inlet, Temp.: 300 ℃, Pressure: 7.07psi, Total flow: 24ml/min, Split flow: 20ml/min, spill ratio: 20:1

④ Column flow: 1ml/min

⑤ Oven temp.: 50℃/5min-10℃/min-320℃/10min　(Total 42min)

⑥ Detector Temp.:300℃, _H2 : 35ml/min, Air: 300ml/min, He: 30ml/min

⑦ GC Model: Agilent 7890

Chroman impurity analysis limit (lower limit) using GC-MS equipment was 5 μg/g, and cases not detected because it was smaller than the analysis limit value were marked as ND (Not dectected).

(2) P-IPP impurity

Gas chromatography mass spectrometry (GC-MS) was performed under the same conditions as the chroman impurity, and the weight ratio of 4-isopropenyl phenol (P-IPP) impurity contained therein based on 1 g of the sample (unit: μg/g) was measured.

Experimental example measurement result division (2. pH adjustment) pH Chroman (μg/g) P-IPP (μg/g) Example 1 8 N.D. 50 Example 2 7 N.D. 60 Example 3 7.5 N.D. 60 Example 4 6 30 90 Comparative Example 1 2 200 500 Comparative Example 2 4 110 260

As shown in Table 1, in the recycled bisphenol A monomer compositions obtained in Examples 1 to 4, chroman impurities were not detected or as low as 30 μg/g, whereas in the recycled bisphenol A monomer compositions obtained in Comparative Examples 1 to 2, Chroman impurities were detected in an excess of 110 μg/g to 200 μg/g compared to the example. In addition, the recycled bisphenol A monomer compositions obtained in Examples 1 to 4 had a P-IPP impurity content of 50 μg/g to 90 μg/g. On the other hand, in the recycled bisphenol A monomer composition obtained in Comparative Examples 1 and 2, an excess of 260 μg/g to 500 μg/g P-IPP impurity was detected compared to the Example. On the other hand, in the case of Reference Examples 1 and 2 , there is a problem that causes corrosion of pipes or the like when applying a purification process under strong base conditions or is disadvantageous compared to the examples in terms of solubility.

Claims (20)

Contains an aromatic diol compound,
The weight ratio of chroman-based impurities measured using gas chromatography mass spectrometry (GC/MS) is less than 110 ug relative to 1 g of the monomer composition for synthesizing recycled plastics,
The monomer composition for synthesizing recycled plastics is a monomer composition for synthesizing recycled plastics, characterized in that recovered from polycarbonate-based resins.
According to claim 1,
The chroman-based impurity is 4- (2,2,4-trimethyl-chroman-4-yl) -phenol, a monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing recycled plastics,
A monomer composition for synthesizing recycled plastics wherein the weight ratio of aromatic monool impurities measured using gas chromatography mass spectrometry (GC/MS) is less than 260 ug relative to 1 g of the monomer composition for synthesizing recycled plastics.
According to claim 3,
The aromatic monool impurity is 4-isopropenyl phenol, a monomer composition for synthesizing recycled plastic.
According to claim 1,
The aromatic diol compound is a monomer composition for synthesizing recycled plastic, characterized in that recovered from polycarbonate-based resin.
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 greater than 4 and less than 9;
After adding the acid, removing chroman-based 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 greater than 4 and less than 9,
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 into an aromatic diol compound.
According to claim 7,
After adding the acid, in the step of removing chroman-based impurities,
A method for preparing a monomer composition for synthesizing recycled plastic, wherein a water layer containing chroman-based impurities and an organic solvent layer containing an aromatic diol compound and a carbonate precursor are separated.
According to claim 7,
After adding the acid, in the step of removing chroman-based impurities,
A method for producing a monomer composition for synthesizing recycled plastic, wherein aromatic monool impurities are removed.
According to claim 7,
The depolymerization reaction of the polycarbonate-based resin,
A method for preparing 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,
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 .