KR20230013564A - Monomer composition for synthesising recycled plastic, prepration method thereof, and recycled plastic, molded product, plasticizer composition using the same - Google Patents

Abstract

The present invention relates to a monomer composition for synthesizing recycled plastic in which the content of formic acid or acetic acid, which are organic impurities, is extremely reduced while recovering from (co)polymers synthesized from monomers including terephthalic acid, a manufacturing method thereof, and recycled plastic, molded articles and plasticizer composition using the same.

Description

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

The present invention is a monomer composition for synthesizing recycled plastics capable of securing high-purity terephthalic acid by significantly reducing the content of organic impurities when terephthalic acid is recovered through depolymerization of a (co)polymer synthesized from monomers including terephthalic acid, and a method for preparing the same , And it relates to recycled plastics, molded articles and plasticizer compositions using the same.

Polyethylene terephthalate (PET) is a thermoplastic (co)polymer, and has excellent properties such as excellent transparency and heat insulation, so it is widely used in wire coverings, household goods, toys, electrical insulators, radios, television cases, and packaging materials.

Although polyethylene terephthalate is widely used for various purposes, concerns about the environment and health 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 polyethylene terephthalate is being conducted.

Terephthalic acid is a useful compound used as a raw material for a wide range of products, and is used as a main raw material for polyethylene terephthalate (PET), polyester fibers, and polyester films for packaging and containers.

Condensation polymerization of ethylene glycol with terephthalic acid to produce polyethylene terephthalate (PET) is a reversible reaction process, and polyethylene terephthalate (PET) can be depolymerized and returned to monomers or oligomers.

As a method of decomposing polyethylene terephthalate (PET) and recovering a monomer as a raw material, various methods have been conventionally proposed. Monomers that can be used in polycondensation to be made into recycled plastics can be obtained through alkaline decomposition of polyethylene terephthalate (PET) waste.

For example, polyethylene terephthalate (PET) decomposition products under basic conditions include ethylene glycol and salts of terephthalic acid, and terephthalic acid is prepared by further neutralizing the salt of terephthalic acid with a strong acid.

However, other organic impurities are detected in the terephthalic acid obtained by the conventional method, and when reused as a raw material for manufacturing high value-added plastics such as PBT / TPEE, there is a limit in that the reaction time is slow and the color quality is reduced.

Therefore, it is necessary to develop a method capable of significantly reducing the organic impurity content in the process of decomposing (co)polymers synthesized from monomers including polyethylene terephthalate (PET) and terephthalic acid and recovering raw material monomers.

The present invention is to provide a monomer composition for synthesizing recycled plastics capable of securing high-purity terephthalic acid by significantly reducing the content of organic impurities when terephthalic acid is recovered through depolymerization of a (co)polymer synthesized from monomers including terephthalic acid. will be.

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

In order to solve the above problems, in the present specification, a weight ratio of the organic impurities including terephthalic acid and further including at least one organic impurity selected from the group consisting of formic acid and acetic acid, and measured using gas chromatography mass spectrometry The monomer composition for synthesizing recycled plastics is less than 5 ug relative to 1 g of the monomer composition for synthesizing recycled plastics, and the monomer composition for synthesizing recycled plastics is recovered from (co)polymers synthesized from monomers including terephthalic acid. Provides a monomer composition for synthesizing recycled plastics .

In the present specification, a step of depolymerizing a (co)polymer synthesized from a monomer including terephthalic acid and removing a diol component; washing the depolymerization reaction product from which the diol component has been removed with a solvent at a temperature of 20° C. or more and 100° C. or less; and dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product, wherein the step of dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product is at 200° C. to 300° C. dissolving in water at a temperature of; and cooling the dissolved solution to a temperature lower than the solution temperature by 50 °C to 200 °C.

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.

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

Hereinafter, a monomer composition for synthesizing recycled plastic according to specific embodiments of the present invention, a method for preparing the same, and a recycled plastic, molded article, and plasticizer composition using the same will be described in more 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 '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.

In the present specification, a (co)polymer refers to a polymer or a copolymer, and the polymer refers to a homopolymer composed of a single repeating unit, and the copolymer refers to a multipolymer containing two or more types of repeating units.

1. Monomer composition for synthesizing recycled plastics

According to one embodiment of the present invention, it contains terephthalic acid and further contains at least one organic impurity selected from the group consisting of formic acid and acetic acid, and the weight ratio of the organic impurity measured using gas chromatography mass spectrometry is recycled plastic A monomer composition for synthesizing recycled plastics may be provided, wherein the monomer composition for synthesizing recycled plastics is less than 5 ug relative to 1 g of the monomer composition for synthesis, and the monomer composition for synthesizing recycled plastics is recovered from a (co)polymer synthesized from monomers including terephthalic acid.

As in the monomer composition for synthesizing recycled plastics of the embodiment, the present inventors have found that organic impurities (formic acid, acetic acid) other than terephthalic acid, which are the main synthetic target materials in the present invention, are recovered from (co)polymers synthesized from monomers including terephthalic acid. The ratio is extremely reduced to less than 5 ug compared to 1 g of the monomer composition for synthesizing recycled plastics, so when synthesizing polyethylene terephthalate or high value-added plastics (PBT, TPEE) using this, the polymerization time is shortened to increase polymerization production efficiency, It was confirmed through experiments that excellent physical properties can be realized in terms of color quality, and the invention was completed.

In particular, the detected amount of organic impurities (formic acid, acetic acid) was significantly reduced compared to the terephthalic acid recovered from the (co)polymer synthesized from the monomers including terephthalic acid obtained by the conventional method, which is the result of the monomer composition for synthesizing recycled plastics described later in the present invention. This seems to be because organic impurities (formic acid, acetic acid) could be effectively removed by the washing process and recrystallization process, which are characteristic of the manufacturing method.

In addition, the present invention does not use toxic organic solvents (eg, DMAc) and organic acids (eg, acetic acid) for purification in the manufacturing method of the monomer composition for synthesizing recycled plastic, unlike conventional terephthalic acid purification methods, water It has the technical advantage of being an eco-friendly process because it can be purified with only water and can also be depolymerized using water as a solvent.

Specifically, the monomer composition for synthesizing recycled plastic according to one embodiment may include terephthalic acid. The terephthalic acid is characterized in that it is recovered from a (co)polymer synthesized from monomers including terephthalic acid used to recover the monomer composition for synthesizing recycled plastics.

That is, it means that terephthalic acid is also obtained as a result of recovering the (co)polymer synthesized from monomers including terephthalic acid in order to obtain the monomer composition for synthesizing recycled plastic according to the embodiment. Therefore, in order to prepare the monomer composition for synthesizing recycled plastic according to one embodiment, the case where new terephthalic acid is added from the outside, apart from the recovery in the (co)polymer synthesized from monomers including terephthalic acid, is not included in the scope of the terephthalic acid of the present invention. don't

Specifically, the recovery from the (co)polymer synthesized from monomers including terephthalic acid means obtained through depolymerization of the (co)polymer synthesized from monomers including terephthalic acid. 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.

For example, when the depolymerization reaction proceeds under the basic condition, a terephthalic acid salt called Na ₂ -TPA and ethylene glycol are primarily produced from the polyethylene terephthalate, and Na ₂ -TPA is converted to TPA through secondary strong acid neutralization. Terephthalic acid can be recovered.

That is, the terephthalic acid recovered from the (co)polymer synthesized from the monomer including terephthalic acid may include a base (alkali) decomposition product of the (co)polymer synthesized from the monomer including terephthalic acid, an acid neutralized product thereof, or a mixture thereof. there is. Specifically, the base (alkali) decomposition product of the (co)polymer synthesized from the monomers including terephthalic acid may include Na ₂ -TPA, and the base (alkali) decomposition product of the (co)polymer synthesized from the monomers including the terephthalic acid. The acid neutralization product of may include terephthalic acid.

The terephthalic acid has a molar ratio of greater than 99.15 mol%, or greater than 99.2 mol%, or less than 100 mol%, or greater than 99.15 mol% and less than 100 mol%, based on 100 mol% of the total monomer compounds contained in the monomer composition for synthesizing recycled plastics; or 99.2 mol% to 100 mol%.

An example of a method for measuring the molar ratio of terephthalic acid is not particularly limited, and for example, ¹ H NMR, ICP-MS analysis, HPLC analysis, and the like can be used without limitation. For the specific methods, conditions, equipment, etc. of NMR, ICP-MS, and HPLC, previously known various contents can be applied without limitation.

As an example of the method for measuring the molar ratio of terephthalic acid, a sample was taken of 5 mg or more and 20 mg or less of the monomer composition for synthesizing recycled plastic under normal pressure, 20 ° C. or more and 30 ° C. or less, and dissolved in 1 ml DMSO-d6 solvent. Next, obtain a ¹ H NMR spectrum through an Agilent DD1 500 MHz NMR instrument, designate all material peaks such as terephthalic acid (TPA) and isophthalic acid (IPA) to be detected using analysis software (MestReC), integrate, and integrate the peaks Based on the value, the molar ratio (mol%) of terephthalic acid contained in 100 mol% of the total monomer compounds analyzed in the sample was calculated.

As such, the molar ratio of terephthalic acid, which is the main synthetic target material in the present invention, is extremely increased to more than 99.15 mol% based on 100 mol% of the total monomer compounds contained in the monomer composition for synthesizing recycled plastic, so that terephthalic acid or impurity monomers (e.g. For example, by minimizing isophthalic acid), it is possible to realize excellent physical properties when synthesizing polyethylene terephthalate or high value-added plastics (PBT, TPEE).

In addition, the monomer composition for synthesizing recycled plastics according to one embodiment may further include isophthalic acid in a molar ratio of less than 0.85 mol% based on 100 mol% of the total monomer compounds contained in the monomer composition for synthesizing recycled plastics.

The isophthalic acid is characterized in that it is recovered from a (co)polymer synthesized from monomers including terephthalic acid used to recover the monomer composition for synthesizing recycled plastics.

That is, isophthalic acid is also obtained as a result of recovering the (co)polymer synthesized from monomers including terephthalic acid in order to obtain the monomer composition for synthesizing recycled plastic according to the embodiment. Therefore, in order to prepare the monomer composition for synthesizing recycled plastic according to an embodiment of the present invention, when new isophthalic acid is externally added apart from recovery in the (co)polymer synthesized from monomers including terephthalic acid, it falls within the scope of isophthalic acid of the present invention. not included.

Specifically, the recovery from the (co)polymer synthesized from monomers including terephthalic acid means obtained through depolymerization of the (co)polymer synthesized from monomers including terephthalic acid. 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.

The isophthalic acid has a molar ratio of less than 0.85 mol%, or 0.5 mol% or less, or 0.1 mol% or less, or 0 mol% or more and less than 0.85 mol% based on 100 mol% of the total monomer compounds contained in the monomer composition for synthesizing recycled plastic. , or 0 mol% or more and 0.5 mol% or less, or 0 mol% or more and 0.1 mol% or less.

An example of a method for measuring the molar ratio of isophthalic acid is not particularly limited, and for example, ¹ H NMR, ICP-MS analysis, HPLC analysis, and the like can be used without limitation. For the specific methods, conditions, equipment, etc. of NMR, ICP-MS, and HPLC, previously known various contents can be applied without limitation.

As an example of the method for measuring the molar ratio of isophthalic acid, a sample of 5 mg or more and 20 mg or less of the monomer composition for synthesizing recycled plastics is taken as a sample and dissolved in 1 ml of DMSO-d6 solvent at normal pressure and at 20 ° C or more and 30 ° C or less. Then, a ¹ H NMR spectrum was obtained through an Agilent DD1 500 MHz NMR instrument, and all material peaks detected, such as terephthalic acid (TPA) and isophthalic acid (IPA), were designated using analysis software (MestReC), integrated, and peak Based on the integral value, the molar ratio (mol%) of isophthalic acid contained in 100 mol% of the total monomer compounds analyzed in the sample was calculated.

As such, the ratio of isophthalic acid, an impurity monomer other than terephthalic acid, which is the main synthesis target material in the present invention, is extremely reduced to less than 0.85 mol% based on 100 mol% of the total monomer compounds contained in the monomer composition for synthesizing recycled plastic, By using this, it is possible to realize excellent physical properties when synthesizing polyethylene terephthalate or high value-added plastics (PBT, TPEE).

In addition, the monomer composition for synthesizing recycled plastic of one embodiment is characterized in that it is recovered from a (co)polymer synthesized from monomers including terephthalic acid. That is, as a result of recovering the (co)polymer synthesized from monomers including terephthalic acid in order to obtain the monomer composition for synthesizing recycled plastics of the embodiment, a monomer composition for synthesizing recycled plastics containing terephthalic acid and isophthalic acid is obtained together. it means.

In the (co)polymers synthesized from the monomers including terephthalic acid, the (co)polymers are meant to include both polymers and copolymers, and collectively refer to reaction products obtained through (co)polymerization of monomers. The (co)polymer may include all low molecular weight compounds, oligomers, and polymers according to the molecular weight range.

The (co)polymer synthesized from the monomers including terephthalic acid may include at least one (co)polymer selected from the group consisting of polyalkylene terephthalate, polyalkylene terephthalate-based copolymer, and thermoplastic polyester elastomer. . That is, the (co)polymer synthesized from the monomers including terephthalic acid includes one polyalkylene terephthalate, one polyalkylene terephthalate copolymer, one thermoplastic polyester elastomer, or a mixture of two or more thereof. can do.

The polyalkylene terephthalate-based copolymer refers to a copolymer obtained by further reacting additional comonomers based on alkylene glycol and terephthalic acid, which are monomers for synthesizing polyalkylene terephthalate.

The (co)polymer synthesized from monomers including terephthalic acid may include a reaction product of terephthalic acid and a comonomer. That is, the monomer including terephthalic acid may further include a comonomer together with terephthalic acid.

Examples of the comonomer capable of reacting with the terephthalic acid are not particularly limited, and specific examples include aliphatic diols, polyalkylene oxides, fatty acids, fatty acid derivatives, or combinations thereof.

The aliphatic diol is, for example, a diol having a number average molecular weight (Mn) of 300 g/mol or less, that is, ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol (1,4 -butane diol, 1,4-BG), 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol (1,4-cycloheanedimethanol, 1,4-CHDM). may be used, and specific examples may include 1,4-butanediol, ethylene glycol, 1,4-cyclohexanedimethanol, or mixtures thereof.

The polyalkylene oxide is a unit constituting the soft fraction, and may include an aliphatic polyether as a component. For example, polyoxyethylene glycol, polypropylene glycol, poly(tetramethylene ether) glycol (PTMEG), polyoxyhexamethylene glycol, ethylene oxide oxide and propylene oxide, ethylene oxide addition polymers of polypropylene oxide glycol, and copolymers of ethylene oxide and tetrahydrofuran may be used, and PTMEG may be used as a specific example. In particular, PTMEG having a number average molecular weight (Mn) of 600 g/mol to 3,000 g/mol, 1,000 g/mol to 2,500 g/mol, or 1,500 g/mol to 2,200 g/mol may be used.

As the fatty acid, for example, one or more of aliphatic carboxylic acid compounds other than terephthalic acid may be used, and adipic acid may be used as a specific example. The fatty acid derivative is a compound derived from the aforementioned fatty acids, and for example, one or more of fatty acid esters, fatty acid chlorides, fatty acid anhydrides, and fatty acid amides may be used, and adipic acid ester may be used as a specific example.

As a specific example, when 1,4-butanediol, which is the aliphatic diol, is used as a comonomer capable of reacting with terephthalic acid, polymerization of terephthalic acid and 1,4-butanediol is performed to obtain the polyalkylene terephthalate. A kind of polybutylene terephthalate (PBT) can be obtained.

In addition, when ethylene glycol, which is the aliphatic diol, is used as a comonomer capable of reacting with terephthalic acid, polyethylene terephthalate (PET), which is a kind of polyalkylene terephthalate, can be obtained through polymerization of terephthalic acid and ethylene glycol. can

In addition, when 1,4-butanediol, the aliphatic diol, and PTMEG, the polyalkylene oxide, are used together as comonomers capable of reacting with the terephthalic acid, thermoplasticity is obtained through polymerization of terephthalic acid, 1,4-butanediol, and PTMEG. Polyester elastomers (TPEE) can be obtained.

In addition, when 1,4-butanediol, the aliphatic diol, and adipic acid, the fatty acid, are used together as comonomers capable of reacting with the terephthalic acid, polymerization of terephthalic acid, 1,4-butanediol, and adipic acid results in the Polybutylene adipate terephthalate (PBAT), which is a type of polyalkylene terephthalate-based copolymer, can be obtained.

In addition, when ethylene glycol and 1,4-cyclohexanedimethanol, which are the aliphatic diols, are used together as comonomers capable of reacting with terephthalic acid, polymerization of terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol Through this, glycol-modified polyethylene terephthalate (PETG), which is a kind of the polyalkylene terephthalate-based copolymer, can be obtained.

As a specific example, the polyalkylene terephthalate is at least one selected from polybutylene terephthalate, polyethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and polytrimethylene terephthalate ( co) polymers.

Further, as a specific example, the polyalkylene terephthalate-based copolymer may include at least one (co)polymer selected from polybutylene adipate terephthalate (PBAT) and glycol-modified polyethylene terephthalate (PETG). .

Meanwhile, the monomer composition for synthesizing recycled plastic may further include at least one organic impurity selected from the group consisting of formic acid and acetic acid. That is, the monomer composition for synthesizing recycled plastics may further contain organic impurities including one type of formic acid, one type of acetic acid, or a mixture of two types thereof. The formic acid and acetic acid are characterized in that they are recovered from (co)polymers synthesized from monomers including terephthalic acid used to recover the monomer composition for synthesizing recycled plastics.

That is, it means that formic acid and acetic acid are also obtained as a result of recovering the (co)polymer synthesized from monomers including terephthalic acid in order to obtain the monomer composition for synthesizing recycled plastic according to an embodiment. Therefore, in order to prepare the monomer composition for synthesizing recycled plastics according to an embodiment of the present invention, when a new organic impurity is externally added apart from recovery in a (co)polymer synthesized from a monomer including terephthalic acid, it falls within the organic impurity category of the present invention. not included.

Specifically, the recovery from the (co)polymer synthesized from monomers including terephthalic acid means obtained through depolymerization of the (co)polymer synthesized from monomers including terephthalic acid. 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.

The weight ratio of the organic impurities measured by gas chromatography mass spectrometry may be less than 5 ug, 0 ug or more, or 0 ug or more and less than 5 ug, based on 1 g of the monomer composition for synthesizing recycled plastic. As will be described later, in the method for preparing a monomer composition for synthesizing recycled plastic, the depolymerization reaction product from which the diol component is removed is washed with a solvent at a temperature of 20 ° C. or more and 100 ° C. or less; and dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product, wherein the step of dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product is at 200° C. to 300° C. dissolving in water at a temperature of; And cooling the dissolved solution to a temperature lower than the solution temperature by 50 °C to 200 °C.

In the present invention, the weight ratio of one kind of formic acid, one kind of acetic acid, or a mixture of two kinds thereof, which are organic impurities other than terephthalic acid, which is the main synthesis target material, is less than 5 ug, or more than 0 ug, compared to 1 g of the monomer composition for synthesizing recycled plastics. , or extremely reduced to less than 0 ug or more and less than 5 ug, it is possible to implement excellent physical properties when synthesizing polyethylene terephthalate or high value-added plastics (PBT, TPEE) using this.

An example of gas chromatography mass spectrometry for measuring the weight ratio of the organic impurities is not particularly limited. For example, 0.5 g of the recycled terephthalic acid monomer composition is sampled under normal pressure and 20 to 30 ° C. and Headspace-GC / MS (Oven temperature: 150 ° C.) Quantitative analysis was performed through the equipment, and the weight ratio (μg/g) of formic acid (FA) and acetic acid (AA) contained in the sample was measured based on 1 g of the sample.

As such, the weight ratio of the organic impurities measured by gas chromatography mass spectrometry in the monomer composition for synthesizing recycled plastics of the present invention is less than 5 ug, or 0 ug or more, or 0 ug or more relative to 1 g of the monomer composition for synthesizing recycled plastics. As it is extremely reduced to less than 5 ug, the polymerization production efficiency can be increased by shortening the polymerization time when synthesizing polyethylene terephthalate or high value-added plastics (PBT, TPEE) using the monomer composition for synthesizing recycled plastics, and in terms of color quality It is possible to realize excellent physical properties.

On the other hand, when the weight ratio of the organic impurities measured by gas chromatography mass spectrometry increases to 5 ug or more relative to 1 g of the monomer composition for synthesizing recycled plastic, the polymerization time is shortened when synthesizing high value-added plastics (PBT, TPEE) As a result, the polymerization production efficiency decreases, and the color quality may deteriorate, such as an increase in the yellow index.

Meanwhile, the monomer composition for synthesizing recycled plastic may further include one or more aromatic impurities selected from the group consisting of 4-carboxybenzaldehyde, benzoic acid, and p-toluic acid. That is, the monomer composition for synthesizing recycled plastics may further include aromatic impurities including one 4-carboxybenzaldehyde, one benzoic acid, one p-toluic acid, or a mixture of two or three thereof. The 4-carboxybenzaldehyde, benzoic acid, and p-toluic acid are characterized in that they are recovered from (co)polymers synthesized from monomers including terephthalic acid used to recover the monomer composition for synthesizing recycled plastics.

That is, as a result of recovering the (co)polymer synthesized from monomers including terephthalic acid in order to obtain the monomer composition for synthesizing recycled plastic of the embodiment, 4-carboxybenzaldehyde, benzoic acid, and p-toluic acid are also obtained means that Therefore, in order to prepare the monomer composition for synthesizing recycled plastics according to an embodiment of the present invention, when a new aromatic impurity is externally added, apart from recovery in a (co)polymer synthesized from a monomer including terephthalic acid, it falls within the scope of the aromatic impurity of the present invention. not included.

Specifically, the recovery from the (co)polymer synthesized from monomers including terephthalic acid means obtained through depolymerization of the (co)polymer synthesized from monomers including terephthalic acid. 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.

The weight ratio of the aromatic impurities measured by liquid chromatography (LC) is less than 100 ug, or less than 50 ug, or less than 10 ug, or less than 1 ug, or more than 0 ug, relative to 1 g of the monomer composition for synthesizing recycled plastics. , or 0 ug or more and less than 100 ug, or 0 ug or more and less than 50 ug, or 0 ug or more and less than 10 ug, or 0 ug or more and less than 1 ug. As will be described later, in the method for preparing a monomer composition for synthesizing recycled plastic, the depolymerization reaction product from which the diol component is removed is washed with a solvent at a temperature of 20 ° C. or more and 100 ° C. or less; and dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product, wherein the step of dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product is at 200° C. to 300° C. dissolving in water at a temperature of; And cooling the dissolved solution to a temperature lower than the solution temperature by 50 °C to 200 °C.

In the present invention, the weight ratio of one 4-carboxybenzaldehyde, one benzoic acid, one p-toluic acid, or a mixture of two or three thereof, which are aromatic impurities other than terephthalic acid, which is the main synthetic target material, is the recycled plastic By extremely reducing to less than 100 ug compared to 1 g of the monomer composition for synthesis, it is possible to implement excellent physical properties when synthesizing polyethylene terephthalate or high value-added plastics (PBT, TPEE) using this.

The example of the liquid chromatography method for measuring the weight ratio of the organic impurities is not particularly limited. For example, 0.5 g of the recycled terephthalic acid monomer composition is sampled under normal pressure and 20 to 30 ° C., and liquid chromatography (LC) The analysis was conducted through the equipment, and the weight ratio (μg/g) of 4-carboxybenzaldehyde (4-CBA), benzoic acid (BZA), and p-toluic acid (p-TA) contained in the sample based on 1 g of the sample was measured.

The monomer composition for synthesizing recycled plastics according to the embodiment may further include a small amount of other additives and solvents, and the types of specific additives or solvents are not particularly limited, and depolymerization of (co)polymers synthesized from monomers including terephthalic acid is performed. Various materials widely used in the terephthalic acid recovery process by 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 subjected to depolymerization of a (co)polymer synthesized from monomers including terephthalic acid, followed by various filtration, purification, and washing to ensure high purity of only terephthalic acid, which is the main synthetic target material in the present invention. , corresponding to the result obtained through the drying process.

The monomer composition for synthesizing recycled plastics of the embodiment is a variety of recycled plastics described later (eg, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polybutylene adipate terephthalate (PBAT), glycol modification) Used as a raw material for the preparation of monomers used in the synthesis of PET resins (glycolmodified polyethylene terephthalate, PETG) and thermoplastic polyester elastomers (TPEE), or other additives (e.g., polyvinylchloride (PVC)) used in the processing of plastics. For example, dioctyl terephthalate plasticizer) can be used as a manufacturing raw material.

2. Manufacturing method of monomer composition for synthesizing recycled plastics

According to another embodiment of the invention, the step of depolymerizing the (co)polymer synthesized from monomers including terephthalic acid, and removing the diol component; washing the depolymerization reaction product from which the diol component has been removed with a solvent at a temperature of 20° C. or more and 100° C. or less; and dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product, wherein the step of dissolving the washed depolymerization product in water and then recrystallizing the washed depolymerization product is at 200° C. to 300° C. dissolving in water at a temperature of; and cooling the dissolved solution to a temperature lower than the solution temperature by 50 °C to 200 °C.

The present inventors applied a washing process and a recrystallization process distinguished by a temperature range in the process of recovering terephthalic acid from a (co)polymer synthesized from monomers including terephthalic acid, as in the method for preparing a monomer composition for synthesizing recycled plastics according to another embodiment of the present invention. As a result, the ratio of isophthalic acid, which is another monomer other than terephthalic acid, which is the main synthesis target material in the present invention, is extremely reduced, as well as organic impurities (acetic acid, formic acid) and aromatic impurities (4-carboxybenzaldehyde, benzoic acid, p- Toluic acid) is extremely reduced, so when synthesizing polyethylene terephthalate or high value-added plastics (PBT, TPEE) using this, the polymerization production efficiency can be increased by shortening the polymerization time, and it is possible to realize excellent physical properties in terms of color quality. It was confirmed through experiments and the invention was completed.

In particular, terephthalic acid recovered from (co)polymers synthesized from monomers containing terephthalic acid obtained by the conventional method usually contains 1 to 2% of isophthalic acid as an impurity, whereas the present invention manufactures a monomer composition for synthesizing recycled plastics, which will be described later. Isophthalic acid and other impurities could be almost completely removed by the high-temperature recrystallization process characteristic of the method.

This is because, in the recrystallization step after dissolving the washed depolymerization reaction product in water, crystals due to increased solubility of terephthalic acid or isophthalic acid or other impurities interposed between crystals can be removed by dissolving them in a solvent as much as possible, and the dissolved terephthalic acid can be removed. This is because since the solubility is poor compared to this impurity, it can be easily precipitated as terephthalic acid crystals through the difference in solubility when the temperature is lowered thereafter.

In addition, through the step of washing the depolymerization product from which the diol component is removed with a solvent at a temperature of 20 ° C. or higher and 100 ° C. or lower, the acid component (HCl) and salt component remaining in the depolymerization product from which the diol component is removed are removed. It is possible to increase the yield and purity of terephthalic acid while suppressing reactor corrosion by removing it by washing as much as possible.

Specifically, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may include depolymerizing a (co)polymer synthesized from monomers including terephthalic acid and removing a diol component.

The (co)polymer synthesized from monomers containing terephthalic acid is a (co)polymer synthesized from monomers containing novel terephthalic acid produced through synthesis, (co)polymers synthesized from monomers containing regenerated terephthalic acid produced through regeneration process, Or, it can be applied regardless of various forms and types such as (co)polymer waste synthesized from monomers including terephthalic acid.

However, if necessary, before proceeding with the depolymerization reaction of the (co)polymer synthesized from the monomers containing terephthalic acid, a pretreatment step of the (co)polymer synthesized from the monomers containing terephthalic acid is performed to obtain The efficiency of the process of recovering terephthalic acid from (co)polymers can be increased. Examples of the pretreatment process include washing, drying, pulverization, and glycol decomposition, and the specific method of each pretreatment process is not limited, and recovery of terephthalic acid by depolymerization of (co)polymer synthesized from monomers including terephthalic acid Various methods widely used in the process can be applied without limitation.

In the depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid, 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. More specifically, the depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid may proceed in the presence of water, alkylene glycol, or alcohol solvent. A specific example of the alkylene glycol solvent is ethylene glycol, and a specific example of the alcohol solvent is ethanol.

In addition, the depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid may proceed under basic conditions. The type of the base is not particularly limited, and sodium hydroxide (NaOH) may be cited as an example.

During the depolymerization of the (co)polymer synthesized from the terephthalic acid-containing monomer, 2.3 mol or less, or 1 mol or more and 2.3 mol or less, or 1.5 mol or more and 2.3 mol or less, relative to 1 mol of the (co)polymer synthesized from the terephthalic acid-containing monomer. It can proceed by reacting the base with the amount.

When the (co)polymer synthesized from the terephthalic acid-containing monomer is reacted with a base in excess of 2.3 mol relative to 1 mol of the (co)polymer synthesized from the terephthalic acid-containing monomer during the depolymerization reaction, the solubility of isophthalic acid salt is reduced and the amount of alkali salt generated is increased. This is because isophthalic acid and sodium (Na), which are impurities other than terephthalic acid, which are the main synthetic target materials, increase, and are difficult to sufficiently remove even by the washing process described later.

In addition, the temperature at which the depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid proceeds is not particularly limited, but may be, for example, 25 ° C. or higher and 200 ° C. or lower, or 130 ° C. or higher and 180 ° C. or lower. In addition, the time for the depolymerization of the (co)polymer synthesized from the monomers including terephthalic acid may be 0 minutes or more and 3 hours or less.

Meanwhile, after depolymerization of the (co)polymer synthesized from monomers including terephthalic acid, the diol component may be removed. For example, the depolymerization reaction product of polyethylene terephthalate (PET) includes ethylene glycol and terephthalate.

Since the main recovery target material of the present invention is terephthalic acid, other by-products can be removed through filtration. The filtered by-products may be recycled without separation and purification in the depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid, or may be recycled through separation and purification using conventional distillation, extraction, and adsorption methods, if necessary.

In addition, since the main recovery target material of the present invention is terephthalic acid, in the case of terephthalic acid, it can be converted to terephthalic acid through an additional neutralization process with a strong acid as described later.

As a specific example, after cooling the depolymerization product of the (co)polymer synthesized from monomers including terephthalic acid to 50° C. or lower, ethylene glycol may be removed through vacuum filtration to obtain terephthalate.

Meanwhile, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may include washing the depolymerization reaction product from which the diol component is removed with a solvent at a temperature of 20 °C or more and 100 °C or less.

As described above, the depolymerization product from which the diol component is removed may contain terephthalic acid obtained by neutralizing terephthalate with ethylene glycol removed. However, since various impurities remain during the recovery process of obtaining terephthalic acid, washing may be performed to sufficiently remove them to secure high-purity terephthalic acid.

Specifically, the washing step may include washing with a solvent at a temperature of 20 °C or more and 100 °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. Accordingly, an effect capable of minimizing corrosion of the reactor by strong acid after the neutralization step may appear.

The step of washing the depolymerization reaction product from which the diol component is removed with a solvent at a temperature of 20° C. or more and 100° C. or less may be repeated at least once. In addition, if necessary, after the step of washing the depolymerization reaction product from which the diol component is removed with a solvent at a temperature of 20 ° C. or higher and 100 ° C. or lower, a step of removing the remaining solvent through filtration may be additionally performed. there is.

The solvent used in the washing step may be water. Eco-friendliness can be improved by performing washing using water without an organic solvent. In addition, when an organic solvent such as ethanol is used instead of the water, salt (NaCl) cannot be effectively removed, which may cause a problem in that the residual amount of sodium (Na) in the composition increases.

The solvent used in the washing step is used in a weight ratio of 1 part by weight or more and 50 parts by weight or less, or 5 parts by weight to 10 parts by weight, based on 1 part by weight of the (co)polymer synthesized from monomers including terephthalic acid used in the depolymerization reaction. can

Meanwhile, the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment may include dissolving the washed depolymerization product in water and then recrystallizing it.

As described above, since various impurities remain during the recovery process of obtaining terephthalic acid, recrystallization can be performed to secure high purity terephthalic acid by sufficiently removing them.

Specifically, the recrystallization step may include dissolving the washed depolymerization reaction product in water and then recrystallizing it. Through the process of dissolving the washed depolymerization reaction product in water and then recrystallizing it, crystallization due to increased solubility of terephthalic acid or its salt contained in the depolymerization reaction product, or isophthalic acid intervening between crystals, organic impurities, aromatic impurities, etc. Impurities can be dissolved as much as possible in a solvent, and since the dissolved terephthalic acid has poor solubility compared to impurities, it can be easily precipitated as terephthalic acid crystals through the difference in solubility when the temperature is lowered thereafter.

More specifically, the step of dissolving the washed depolymerization reaction product in water and recrystallizing it may include dissolving the washed depolymerization reaction product in water at a temperature of 200 °C to 300 °C, 200 °C to 250 °C, or 205 °C to 250 °C. dissolving in; and cooling the dissolved solution to a temperature lower than the solution temperature by 50 °C to 200 °C.

Although the high-temperature temperature range and the cooling temperature range in which recrystallization proceeds are relatively mild, there is an advantage in that impurities can be removed at a high level and the recovery efficiency of terephthalic acid can be increased. The temperature condition refers to the temperature inside the container at which recrystallization by the solvent proceeds, and various heating and cooling mechanisms can be applied without limitation to maintain a high temperature and a low temperature outside the room temperature.

Specific examples of the specific melting, cooling conditions, apparatus, and method of the recrystallization process are not particularly limited, and various methods widely used in the existing terephthalic acid recrystallization technology can be applied without limitation.

In the step of dissolving the washed depolymerization reaction product in water at a temperature of 200° C. to 300° C., 1 part to 60 parts by weight, or 10 parts by weight, based on 1 part by weight of the (co)polymer synthesized from monomers including terephthalic acid. to 50 parts by weight of water may be used. If less than 1 part by weight of water is used with respect to 1 part by weight of the (co)polymer synthesized from the monomers including terephthalic acid, the temperature for dissolving the terephthalic acid contained in the washed depolymerization reaction product becomes too high, resulting in poor process efficiency. , it is not easy to remove impurities through recrystallization. On the other hand, when more than 60 parts by weight of water is used with respect to 1 part by weight of the (co)polymer synthesized from monomers including terephthalic acid, the solubility of terephthalic acid contained in the washed depolymerization reaction product becomes excessively high, resulting in a yield of terephthalic acid recovered after recrystallization. This decreases, and process efficiency due to the use of a large amount of solvent may decrease.

More specifically, dissolving the washed depolymerization product in water at a temperature of 200 ° C to 300 ° C includes dissolving the washed depolymerization product in water at a temperature of 200 ° C to 220 ° C; , The content of the water may be 30 parts by weight to 60 parts by weight based on 1 part by weight of the (co)polymer synthesized from monomers including terephthalic acid.

In addition, the step of dissolving the washed depolymerization product in water at a temperature of 200 ° C to 300 ° C includes dissolving the washed depolymerization product in water at a temperature of 240 ° C to 300 ° C; The water content may be 1 part by weight to 20 parts by weight, or 5 parts by weight to 20 parts by weight based on 1 part by weight of the (co)polymer synthesized from monomers including terephthalic acid.

Meanwhile, in the step of dissolving the washed depolymerization reaction product in water and then recrystallizing it, after dissolving the washed depolymerization reaction product in water at a temperature of 200° C. to 300° C., the dissolved solution is kept at a temperature lower than the solution temperature. It may include cooling to a lower temperature of 50 °C to 200 °C.

Through the cooling, crystallized terephthalic acid may be obtained through filtration or the like through a difference in solubility between terephthalic acid and impurities, and impurities may be removed while dissolved in a solvent.

Specific cooling conditions of the cooling step are not particularly limited, but, for example, the dissolved solution may be cooled to a temperature lower than the solution temperature by 50 °C to 200 °C. That is, the difference between the temperature of the solution and the cooling temperature (a difference value obtained by subtracting the cooling temperature from the temperature of the solution) may be 50 °C to 200 °C. Thus, terephthalic acid dissolved in the high-temperature solution can be precipitated and recovered due to the difference in solubility between the solution temperature and the cooling temperature.

Although specific cooling conditions of the cooling step are not particularly limited, cooling may be performed at a temperature of, for example, 100 ° C or less, or 50 ° C or more and 100 ° C or less, or 80 ° C or more and 100 ° C or less. For the specific drying equipment and method used during the cooling, various previously known cooling technologies can be applied without limitation.

Meanwhile, the method for preparing a monomer composition for synthesizing recycled plastics according to another embodiment further includes, before the step of washing the depolymerization product from which the diol component is removed, neutralization of the depolymerization product from which the diol component is removed with an acid. can include

For example, polyethylene terephthalate (PET) alkali decomposition products include ethylene glycol and terephthalate, but the main recovery target material of the present invention is terephthalic acid, so in the case of terephthalate obtained by the alkali decomposition, terephthalic acid through an additional neutralization process with a strong acid can be converted to That is, when the depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid is alkaline decomposition, a neutralization reaction step by acid may be performed.

A strong acid may be used as the acid used during the neutralization reaction, and examples thereof include hydrochloric acid (HCl). Due to the neutralization reaction by the strong acid, pH may satisfy 4 or less or 2 or less at the end of the neutralization reaction. During the neutralization reaction, the temperature may be adjusted to 25° C. or higher and 100° C. or lower.

In addition, if necessary, after the step of acid neutralization of the depolymerization reaction product from which the diol component has been removed, a step of removing remaining impurities through filtration may be additionally performed.

Meanwhile, in the method for preparing a monomer composition for synthesizing recycled plastic according to another embodiment, after depolymerizing a (co)polymer synthesized from monomers including terephthalic acid and removing the diol component, the depolymerization product from which the diol component is removed is prepared. Further purification steps may be included.

Residual impurities can be removed through the purification, specific purification conditions are not greatly limited, and various conventionally known purification techniques can be applied without limitation to specific purification equipment and methods.

For a specific example, the step of purifying the depolymerization product from which the diol component is removed may include dissolving and filtering the depolymerization product from which the diol component is removed; and an adsorption step through an adsorbent.

In the step of dissolving and filtering the depolymerization product from which the diol component is removed, water may be used as a solvent for dissolving the depolymerization product from which the diol component is removed, and the dissolution temperature may be carried out at 25° C. or more and 100° C. or less. there is. Through this, it is possible to remove the (co)polymer synthesized from monomers including residual terephthalic acid that did not react in the depolymerization reaction.

In the adsorption step through the adsorbent, activated carbon may be used as an example of the adsorbent.

If necessary, an extraction step, a washing step, a precipitation step, a recrystallization step, a drying step, etc. may be additionally applied without limitation in the step of purifying the depolymerization reaction product from which the diol component is removed.

When the step of purifying the depolymerization product from which the diol component is removed is performed, the step of washing the depolymerization product from which the diol component is removed may be performed after the step of purifying the depolymerization product from which the diol component is removed. there is.

In addition, as described above, when the depolymerization reaction is alkaline decomposition, when the step of purifying the depolymerization product from which the diol component is removed is performed, the diol component described above is obtained after the step of purifying the depolymerization product from which the diol component is removed. A step of washing the depolymerization product from which the diol component is removed may be performed after the neutralization of the removed depolymerization product with an acid.

Meanwhile, the method for preparing the monomer composition for synthesizing recycled plastic according to another embodiment may further include a drying step after the step of washing the depolymerization reaction product from which the diol component is removed. The remaining solvent may be removed through the drying, and specific drying conditions are not greatly limited, but, for example, drying may be performed at a temperature of 100 ° C. or more and 150 ° C. or less. 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. The contents of the monomer composition for synthesizing recycled plastics include all of the contents described above in the embodiment.

Examples corresponding to the recycled plastics are not particularly limited, and various plastics synthesized with terephthalic acid as a monomer can be applied without limitation, and more specific examples include (co)polymers synthesized from monomers including terephthalic acid.

In the (co)polymers synthesized from the monomers including terephthalic acid, the (co)polymers are meant to include both polymers and copolymers, and collectively refer to reaction products obtained through (co)polymerization of monomers. The (co)polymer may include all low molecular weight compounds, oligomers, and polymers according to the molecular weight range.

The (co)polymer synthesized from the monomers including terephthalic acid may include at least one (co)polymer selected from the group consisting of polyalkylene terephthalate, polyalkylene terephthalate-based copolymer, and thermoplastic polyester elastomer. . That is, the (co)polymer synthesized from the monomers including terephthalic acid includes one polyalkylene terephthalate, one polyalkylene terephthalate copolymer, one thermoplastic polyester elastomer, or a mixture of two or more thereof. can do.

The polyalkylene terephthalate-based copolymer refers to a copolymer obtained by further reacting an additional comonomer based on alkylene glycol and terephthalic acid, which are monomers for synthesizing polyalkylene terephthalate.

Examples of the comonomer capable of reacting with the high-purity terephthalic acid contained in the monomer composition for synthesizing recycled plastics of the embodiment are not particularly limited, and specific examples include aliphatic diols, polyalkylene oxides, fatty acids, fatty acid derivatives, or combination can be found.

The aliphatic diol is, for example, a diol having a number average molecular weight (Mn) of 300 g/mol or less, that is, ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol (1,4 -butane diol, 1,4-BG), 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol (1,4-cycloheanedimethanol, 1,4-CHDM). may be used, and specific examples may include 1,4-butanediol, ethylene glycol, 1,4-cyclohexanedimethanol, or mixtures thereof.

The polyalkylene oxide is a unit constituting the soft fraction, and may include an aliphatic polyether as a component. For example, polyoxyethylene glycol, polypropylene glycol, poly(tetramethylene ether) glycol (PTMEG), polyoxyhexamethylene glycol, ethylene oxide oxide and propylene oxide, ethylene oxide addition polymers of polypropylene oxide glycol, and copolymers of ethylene oxide and tetrahydrofuran may be used, and PTMEG may be used as a specific example. In particular, PTMEG having a number average molecular weight (Mn) of 600 g/mol to 3,000 g/mol, 1,000 g/mol to 2,500 g/mol, or 1,500 g/mol to 2,200 g/mol may be used.

As the fatty acid, for example, one or more types of aliphatic carboxylic acid compounds other than terephthalic acid may be used, and adipic acid may be used as a specific example. The fatty acid derivative is a compound derived from the aforementioned fatty acids, and for example, one or more of fatty acid esters, fatty acid chlorides, fatty acid anhydrides, and fatty acid amides may be used, and adipic acid ester may be used as a specific example.

As a specific example, when 1,4-butanediol, an aliphatic diol, is used as a comonomer capable of reacting with high-purity terephthalic acid contained in the monomer composition for synthesizing recycled plastics according to one embodiment, terephthalic acid and 1,4 -Polybutylene terephthalate (PBT), which is a kind of polyalkylene terephthalate, can be obtained through polymerization of butanediol.

In addition, when ethylene glycol, the aliphatic diol, is used as a comonomer capable of reacting with high-purity terephthalic acid contained in the monomer composition for synthesizing recycled plastics of the embodiment, the polyalkylene is obtained through polymerization of terephthalic acid and ethylene glycol. Polyethylene terephthalate (PET), which is a type of terephthalate, can be obtained.

In addition, when the aliphatic diol, 1,4-butanediol, and the polyalkylene oxide, PTMEG, are used together as a comonomer capable of reacting with high-purity terephthalic acid contained in the monomer composition for synthesizing recycled plastics of the embodiment, terephthalic acid Thermoplastic polyester elastomer (TPEE) can be obtained through polymerization of 1,4-butanediol and PTMEG.

In addition, when 1,4-butanediol, which is an aliphatic diol, and adipic acid, which is a fatty acid, are used together as a comonomer capable of reacting with high-purity terephthalic acid contained in the monomer composition for synthesizing recycled plastics of the embodiment, terephthalic acid and 1 Polybutylene adipate terephthalate (PBAT), which is a kind of the polyalkylene terephthalate-based copolymer, can be obtained through polymerization of ,4-butanediol and adipic acid.

In addition, when ethylene glycol and 1,4-cyclohexanedimethanol, which are aliphatic diols, are used together as comonomers capable of reacting with high-purity terephthalic acid contained in the monomer composition for synthesizing recycled plastics of the embodiment, terephthalic acid and ethylene Through polymerization of glycol and 1,4-cyclohexanedimethanol, glycol-modified polyethylene terephthalate (PETG), which is a kind of the polyalkylene terephthalate-based copolymer, can be obtained.

As a specific example, the polyalkylene terephthalate is at least one selected from polybutylene terephthalate, polyethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and polytrimethylene terephthalate ( co) polymers.

Further, as a specific example, the polyalkylene terephthalate-based copolymer may include at least one (co)polymer selected from polybutylene adipate terephthalate (PBAT) and glycol-modified polyethylene terephthalate (PETG). .

Examples of the method for reacting the monomer composition for synthesizing recycled plastic and the comonomer are not particularly limited, and various previously known methods may be applied without limitation. However, as specific examples of the reaction between the monomer composition for synthesizing recycled plastic and the comonomer, melt polycondensation and solid phase polymerization may be mentioned.

As a more specific example, in the case of producing thermoplastic polyester elastomer (TPEE) from the recycled plastic, aromatic dicarboxylic acid, aliphatic diol, and polyalkylene oxide are mixed with titanium butoxide (TBT) at 180 ° C. or more and 250 ° C. or less at 30 ° C. After generating BHBT (bis(4-hydroxy) butyl terephthalate) oligomer by esterification reaction for more than 210 minutes, the TBT catalyst is reintroduced, and the melt polycondensation reaction is carried out at 200 ℃ or more and 270 ℃ or less for 20 minutes or more and 240 minutes During the following, it can be carried out while reducing the pressure in stages from 760 torr to 0.3 torr. After completion of the melt polycondensation reaction, nitrogen pressure may be discharged from the reactor to pelletize the strand through pelletizing.

Then, solid-state polymerization may be performed on the pellets in a solid-state polymerization reactor or a rotatable vacuum dryer at a temperature range of 140 ° C. to 200 ° C. for 10 hours or more and 24 hours or less under a high vacuum under an inert atmosphere such as nitrogen.

Further, in the case of producing polyalkylene terephthalate from the recycled plastic, the aromatic dicarboxylic acid and an aliphatic diol having a number average molecular weight (Mn) of 300 g/mol or less may be melt-polymerized and then solid-state polymerized.

As a specific example, the polyalkylene terephthalate may be at least one selected from polybutylene terephthalate, polyethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polytrimethylene terephthalate. there is.

The polyalkylene terephthalate resin is obtained by putting low molecular weight pellets obtained through melt polymerization into a solid-state polymerization reactor and reacting under high vacuum and inert conditions, as suggested in the solid-state polymerization of thermoplastic polyester elastomer (TPEE), to obtain high molecular weight. of resin can be obtained.

As a result of the reaction of the monomer composition for synthesizing recycled plastics and comonomers, the polybutylene terephthalate, polyethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, Or, a specific method for producing polybutylene adipate terephthalate is not particularly limited, and various processes widely known in the field of synthesizing existing recycled plastics may be applied without limitation.

The recycled plastic may have a yellow index of 50 or less, or 5 or less, or 0.5 or more, or 0.5 to 50, or 0.5 to 5.

When the yellowness index of the recycled plastic is excessively increased to more than 50, color characteristics of the recycled plastic are deteriorated due to yellowing of the recycled plastic. An example of a method for measuring the yellow index of the recycled plastic is not significantly limited, and various color characteristic measurement methods in the plastic field can be applied without limitation.

However, as an example of a method for measuring the yellow index of the recycled plastic, it can be measured in a reflection mode using HunterLab UltraScan PRO Spectrophotometer equipment.

The recycled plastic has a color coordinate b* value of 3 or less, or 2 or less, or 1 or less, or 0.1 or more, or 0.5 or more, or 0.9 or more, or 0.1 to 3, or 0.1 to 2, or 0.1 to 1, or 0.5 to 3, or 0.5 to 2, or 0.5 to 1, or 0.9 to 3, or 0.9 to 2, or 0.9 to 1.

In addition, the recycled plastic may have a color coordinate L* value of 84.5 or more, or 85 or more, or 86 or less, or 84.5 to 86, or 85 to 86.

The recycled plastic has a color coordinate a* value of -0.3 or less, or -0.4 or less, or -0.5 or less, or -0.6 or less, or -1 or more, or -1 to -0.3, or -1 to -0.4, or -1 to -0.5, or -1 to -0.6.

When the value of the color coordinate b* of the recycled plastic is excessively increased to more than 3, color characteristics of the recycled plastic are deteriorated due to yellowing of the recycled plastic. An example of a method for measuring the color coordinates L*, a*, and b* of the recycled plastic is not particularly limited, and various color characteristic measurement methods in the plastics field can be applied without limitation.

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

The recycled plastic may have a melt fluidity index of 5 g/10 min to 30 g/10 min, or 15 g/10 min to 25 g/10 min, as measured by ASTM D1238. When the melt fluidity index of the recycled plastic increases to more than 30 g/10 min, molding of the recycled plastic becomes difficult.

However, as an example of a method for measuring the melt fluidity index of the recycled plastic, it may be measured by applying a load at 230 ° C to 250 ° C, 2.16 kg, for 4 minutes in accordance with ASTM D1238.

More specifically, for example, in the case of thermoplastic polyester elastomer (TPEE), it can be measured by applying a load at 230 ° C., 2.16 kg, for 4 minutes in accordance with ASTM D1238. In addition, in the case of the polyalkylene terephthalate, it can be measured by applying a load at 250 ° C., 2.16 kg, for 4 minutes in accordance with ASTM D1238.

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 automobiles, electrical and electronic products, communication products, and household goods.

5. Plasticizer composition

According to another embodiment of the present invention, a plasticizer composition comprising a reaction product of the monomer composition for synthesizing recycled plastic according to one embodiment and an alcohol may be provided. The contents of the monomer composition for synthesizing recycled plastics include all of the contents described above in the embodiment.

In general, plasticizers are appropriately added to resins such as polyvinyl chloride (PVC) and various additives such as fillers, stabilizers, pigments, and anti-fogging agents to impart various processing properties to wire by processing methods such as extrusion molding, injection molding, and calendering. , pipes, flooring, wallpaper, sheets, artificial leather, tarpaulins, tapes, and products in the food packaging industry.

Typically, plasticizers react with alcohols with polycarboxylic acids such as phthalic acid and adipic acid to form the corresponding esters. In addition, in consideration of domestic and foreign regulations on phthalate-based plasticizers harmful to the human body, research on plasticizer compositions that can replace phthalate-based plasticizers such as terephthalate-based, trimellitate-based, and other polymer-based plasticizers continues.

The reaction product of the monomer composition for synthesizing recycled plastic and alcohol of the embodiment may include a terephthalate-based compound. Specifically, a terephthalate-based compound may be obtained through a direct esterification reaction between terephthalic acid and alcohol contained in the monomer composition for synthesizing recycled plastic according to the embodiment.

The direct esterification reaction may include adding terephthalic acid to alcohol and then adding a catalyst and reacting under a nitrogen atmosphere; removing unreacted alcohol and neutralizing unreacted acid; And dehydrating and filtering by distillation under reduced pressure; it can be prepared as.

Examples of the terephthalate-based compound are not particularly limited, but examples include dioctyl terephthalate (DOTP), diisononyl terephthalate (DINTP), diisodecyl terephthalate (DIDTP), or di(2-propylheptyl) Terephthalate (DPHTP) etc. are mentioned.

The terephthalate-based compound may be prepared through a direct esterification reaction in which one alcohol selected from the group consisting of octanol, isononyl alcohol, isodecyl alcohol, and 2-propylheptyl alcohol reacts with terephthalic acid.

The plasticizer composition can be applied to the manufacture of electric wires, flooring materials, automobile interior materials, films, sheets, wallpaper or tubes.

According to the present invention, when terephthalic acid is recovered through depolymerization of a (co)polymer synthesized from monomers including terephthalic acid, the content of organic impurities is significantly reduced to secure high-purity terephthalic acid, a monomer composition for synthesizing recycled plastics, A manufacturing method, and recycled plastics, molded articles, and plasticizer compositions using the same 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.

<Example>

Example 1

(1) Preparation of recycled terephthalic acid monomer composition

After putting 192 g (1 mol) of polyethylene terephthalate (PET) bottle scrap, 1250 g (about 20 mol) of ethylene glycol (EG), and 82 g (2.05 mol) of sodium hydroxide (NaOH) into a 3L SUS reactor, the system was closed. The PET depolymerization reaction was performed by stirring at 180 °C for 2 hours. The product of the depolymerization reaction was cooled to 20 to 30 °C, and then sodium terephthalate (Na ₂ -TPA) was obtained through vacuum filtration.

After the filtrate containing the sodium terephthalate (Na ₂ -TPA) was completely dissolved in water, unreacted PET and other solid impurities were removed through vacuum filtration again. Thereafter, the filtrate was purified through activated carbon adsorption, neutralized using 6M HCl at 20-30 ° C., and the slurry lowered to pH 2 or less was vacuum-filtered again to obtain terephthalic acid (TPA).

In order to remove NaCl generated during the neutralization process, using 1920 g of water 10 times the mass of PET used, the mixture was washed at 20 to 30 ° C and vacuum filtered.

Thereafter, 9600 g of water, which is 50 times the mass of PET used, was added, the temperature was raised to 205 ° C., and all was dissolved at 205 ° C., and the TPA aqueous solution was cooled to 100 ° C. or less at normal pressure to recrystallize terephthalic acid. Terephthalic acid (TPA) crystals were recovered by vacuum filtration at ~30 °C.

Thereafter, a recycled terephthalic acid monomer composition in which recycled terephthalic acid (TPA) was recovered was prepared by drying in a convection oven at 120 °C.

(2) Manufacture of recycled plastics

200 g of the recycled terephthalic acid monomer composition obtained in (1) of Example 1, 200 g of 1,4-butylene glycol, poly (tetramethylene ether) glycol having a number average molecular weight of 1,000-2,000 g / mol 125 g of glycol, PTMEG) was placed in an ester interchange reactor, and 0.1 wt% of TBT catalyst was added thereto. The reaction was carried out for 120 to 180 minutes while maintaining 200 to 240 ° C., and the reaction was terminated when the reaction rate (a value obtained by converting the amount of water as a reaction effluent into a reaction rate) reached 90% or more to obtain an oligomer.

Thereafter, the prepared oligomer was transferred to a polycondensation reactor, and 0.1 wt% of the TBT catalyst, 0.14 to 0.15 wt% of a hindered phenolic antioxidant, and 0.15 to 0.2 wt% of an aromatic amine antioxidant or a sulfur-based stabilizer were added and 230 While maintaining ~ 250 ℃, perform melt polycondensation under reduced pressure from 760 torr to 0.3 torr for 30 minutes, and then perform melt polycondensation under high vacuum conditions of 0.3 torr or less until the torque applied to the stirrer reaches the desired torque. did After the reaction was terminated, discharged using nitrogen pressure, stranded, cooled, and then pelletized to prepare a thermoplastic polyester elastomer (TPEE) resin.

Example 2

(1) Preparation of recycled terephthalic acid monomer composition

192 g (1 mol) of polyethylene terephthalate (PET) bottle scrap, 1600 g of water, and 82 g (2.05 mol) of sodium hydroxide (NaOH) were put into a 3L SUS reactor, and then stirred at 180 ° C for 2 hours in a closed system. A PET depolymerization reaction was performed. The product of the depolymerization reaction was cooled to 50° C. or lower, and then unreacted PET and other solid impurities were removed through vacuum filtration.

Thereafter, the filtrate was purified through activated carbon adsorption, neutralized using 6M HCl at 20-30 ° C., and the slurry lowered to pH 2 or less was vacuum-filtered again to obtain terephthalic acid (TPA).

In order to remove NaCl generated during the neutralization process, using 1920 g of water 10 times the mass of PET used, the mixture was washed at 20 to 30 ° C and vacuum filtered.

Thereafter, 1920 g of water, which is 10 times the mass of PET used, was added, heated to 250 ° C., dissolved at 250 ° C., and the TPA aqueous solution was cooled to 100 ° C. or lower at normal pressure to recrystallize terephthalic acid. Terephthalic acid (TPA) crystals were recovered by vacuum filtration at ~30 °C.

Thereafter, a recycled terephthalic acid monomer composition in which recycled terephthalic acid (TPA) was recovered was prepared by drying in a convection oven at 120 °C.

(2) Manufacture of recycled plastics

Thermoplastic polyester was prepared in the same manner as in (2) of Example 1, except that the recycled terephthalic acid monomer composition obtained in (1) of Example 2 was used instead of the recycled terephthalic acid monomer composition obtained in (1) of Example 1. An elastomer (TPEE) resin was prepared.

Example 3

(1) Preparation of recycled terephthalic acid monomer composition

A recycled terephthalic acid monomer composition was prepared in the same manner as in Example 1 (1).

(2) Manufacture of recycled plastics

300 g of the recycled terephthalic acid monomer composition obtained in (1) of Example 1 and 300 g of 1,4-butylene glycol were placed in an esterification reactor, and 0.1 wt% of a TBT catalyst was added thereto. The reaction was carried out for 120 to 180 minutes while maintaining 200 to 240 ° C., and the reaction was terminated at the time when the reaction rate (when converting the amount of water as the reaction effluent into the reaction rate) was 90% or more to obtain an oligomer.

Thereafter, the prepared oligomer was transferred to a polycondensation reactor, and melt polycondensation was performed under reduced pressure from 760 torr to 0.3 torr for 30 minutes while maintaining a temperature of 230 to 260 ° C. The melt polycondensation reaction was performed under a high vacuum condition of 0.3 torr or less until After the reaction was terminated, the mixture was discharged using nitrogen pressure to form a strand, cooled, and then pelletized to prepare a polybutylene terephthalate (PBT) resin.

<Comparative example>

Comparative Example 1

As shown in Table 1 below, except for the second washing at a temperature of 20 to 30 ° C. using 3840 g of water 20 times the mass of PET used without performing the recrystallization step of (1) of Example 1 above. In the same manner as in Example 1, a recycled terephthalic acid monomer composition and recycled plastic were prepared.

<Reference example>

Reference example 1

A plastic was prepared in the same manner as in Example 1, except that a commercially available TPA reagent (manufacturer: TCI) was used instead of the recycled terephthalic acid monomer composition.

<Experimental Example 1>

For the recycled terephthalic acid 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. Content of terephthalic acid (TPA) and isophthalic acid (IPA)

5 to 20 mg of the recycled terephthalic acid monomer composition was taken as a sample at normal pressure and 20 to 30 ° C., dissolved in 1 ml DMSO-d6 solvent, and then ¹ H NMR spectrum was obtained using an Agilent DD1 500 MHz NMR instrument. All material peaks detected, such as terephthalic acid (TPA) and isophthalic acid (IPA), were respectively designated and integrated using analysis software (MestReC). Based on the peak integral value, the molar ratio (mol%) of terephthalic acid and isophthalic acid contained in 100 mol% of the total monomer compounds analyzed in the sample was calculated.

2. Formic acid (FA), acetic acid (AA) content

0.5 g of the recycled terephthalic acid monomer composition was taken as a sample under normal pressure and 20 to 30 ° C., and the analysis was performed using Headspace-GC / MS (oven temperature: 150 ° C.) equipment, based on 1 g of the sample. FA) and acetic acid (AA) weight ratio (μg/g) were measured.

3. 4-carboxybenzaldehyde (4-CBA), benzoic acid (BZA), p-toluic acid (p-TA) content

0.5 g of the recycled terephthalic acid monomer composition was taken as a sample under normal pressure and 20 to 30 ° C., and the analysis was performed using liquid chromatography (LC) equipment, and 4-carboxybenzaldehyde (4-carboxybenzaldehyde (4- CBA), benzoic acid (BZA), and p-toluic acid (p-TA) weight ratios (μg/g) were measured. The analysis limit (lower limit) for each substance using LC equipment was 20 μg/g for 4-CBA, 80 μg/g for BZA, and 100 μg/g for p-TA, respectively. (Not detected).

Experimental Example 1 measurement results division depolymerization solvent washing condition recrystallization conditions TPA
(mole%) IPA
(mole%) FA
(μg/g) AA
(μg/g) 4-CBA
(μg/g) BZA
(μg/g) p-TA
(μg/g) Example 1 Ethylene glycol 20 ~ 30 ℃ / water (10 times the mass of PET) [Dissolution] 205 ℃ / water (50 times the mass of PET)
[Cooling]
100 ℃ or less, normal pressure 100 0 4.3 0.6 N.D. N.D. N.D. Example 2 water 20 ~ 30 ℃ / water (10 times the mass of PET) [Dissolution] 250 ℃ / water (10 times the mass of PET)
[Cooling]
100 ℃ or less, normal pressure 99.6 0.4 4.0 0.5 N.D. N.D. N.D. Comparative Example 1 Ethylene glycol [1st] 20 ~ 30 ℃ / water (10 times the mass of PET) [2nd] 20 ~ 30 ℃ / water (20 times the mass of PET) - 99.1 0.9 13.5 2.0 N.D. N.D. N.D. Reference example 1 - - - 100 0 1.9 299.6 153 N.D. 136

As shown in Table 1, the recycled terephthalic acid monomer composition obtained in Example 1 contained terephthalic acid at 100 mol% of the monomers, and the recycled terephthalic acid monomer composition obtained in Example 2 contained terephthalic acid at 99.6 mol%. On the other hand, among the monomers included in the recycled terephthalic acid monomer composition obtained in Comparative Example 1, isophthalic acid, an impurity, was contained in an excess of 0.9 mol% compared to the example, so the terephthalic acid purification efficiency was greatly reduced. was able to confirm that

On the other hand, in the recycled terephthalic acid monomer composition obtained in Examples 1 and 2, formic acid (FA), which is another impurity, was detected at 4.0 μg/g to 4.3 μg/g and acetic acid (AA) was detected at 0.5 μg/g to 0.6 μg/g, and 4 - Carboxybenzaldehyde (4-CBA), benzoic acid (BZA), and p-toluic acid (p-TA) were not detected, indicating excellent purification efficiency for impurities.

On the other hand, in the recycled terephthalic acid monomer composition obtained in Comparative Example 1, 13.5 μg/g of formic acid (FA) and 2.0 μg/g of acetic acid (AA), which are other impurities, were detected in excess compared to the Example, confirming poor purification efficiency for impurities. could

In addition, in the commercially available TPA reagent (manufacturer: TCI) of Reference Example 1, acetic acid (AA), which is another impurity, was 299.6 μg/g, 4-carboxybenzaldehyde (4-CBA) was 153 μg/g, and p-toluic acid (p-TA) was detected in excess compared to the example at 136 μg/g, confirming poor purification efficiency for impurities.

<Experimental Example 2>

For the recycled plastics obtained in the above Examples and Comparative Examples, physical properties were measured by the following method, and the results are shown in Table 2.

1. Polymerization time

When preparing the thermoplastic polyester elastomer (TPEE) obtained in the above Examples and Comparative Examples, the time taken from the time when the oligomer was transferred to the polycondensation reactor and the pressure was reduced until the target torque was reached was measured, and this was calculated as the polymerization time. evaluated.

2. Melt Flow Index (MFI)

With respect to the thermoplastic polyester elastomer (TPEE) obtained in the above Examples and Comparative Examples, a load was applied at 230 ° C. for 4 minutes at 2.16 kg in accordance with ASTM D1238 to measure the melt fluidity index.

3. Yellow index (YI), color coordinates (L*, a*, b*)

Injection specimens (1.5T) were prepared from the thermoplastic polyester elastomer (TPEE) obtained in the above Examples and Comparative Examples, and the specimens were analyzed in a reflection mode using HunterLab UltraScan PRO Spectrophotometer equipment.

Experimental Example 2 measurement result division depolymerization solvent washing condition recrystallization conditions Polymerization time (minutes) MFI (g/10min) YI L* a* b* Example 1 Ethylene glycol 20 ~ 30 ℃ / water (10 times the mass of PET) [Dissolution] 205 ℃ / water (50 times the mass of PET)
[Cooling]
100 ℃ or less, normal pressure 122 24 3.0 85.0 -0.6 1.7 Example 2 water 20 ~ 30 ℃ / water (10 times the mass of PET) [Dissolution] 250 ℃ / water (10 times the mass of PET)
[Cooling]
100 ℃ or less, normal pressure 127 23 1.1 85.0 -0.6 0.9 Comparative Example 1 Ethylene glycol [1st] 20 ~ 30 ℃ / water (10 times the mass of PET) [2nd] 20 ~ 30 ℃ / water (20 times the mass of PET) - 183 24 8.7 83.5 0.0 4.8 Reference example 1 - - - 129 22 6.2 85.0 0.0 3.4

As shown in Table 2, in the case of the TPEE (co)polymer synthesized from the recycled terephthalic acid monomer composition obtained in Examples 1 and 2, the polymerization time was as short as 122 to 127 minutes, and the melt fluidity index was 23 g/10 min to 24 g/10 min, yellow index (YI) of 1.1 to 3.0, color coordinate L* of 85.0, a* of -0.6, and b* of 0.9 to 1.7, showing excellent color quality.

On the other hand, in the case of the TPEE (co)polymer synthesized from the recycled terephthalic acid monomer composition obtained in Comparative Example 1, the polymerization time was 183 minutes, which was longer than that of Example, the yellowness index (YI) was 8.7, the color coordinate L* was 83.5, and the a* was 0, b* was 4.8, indicating poor color quality.

In addition, in the case of the TPEE (co)polymer synthesized from the commercially available TPA reagent (manufacturer: TCI) of Reference Example 1, the polymerization time was 129 minutes, which was longer than that of the Example, yellowness index (YI) was 6.2, and color coordinate L* was 85, a* was 0, and b* was 3.4, indicating poor color quality.

Claims (20)

Contains terephthalic acid,
further comprising at least one organic impurity selected from the group consisting of formic acid and acetic acid;
The weight ratio of the organic impurities measured by gas chromatography mass spectrometry is less than 5 ug relative to 1 g of the monomer composition for synthesizing recycled plastics,
The monomer composition for synthesizing recycled plastics is characterized in that recovered from a (co)polymer synthesized from a monomer containing terephthalic acid, a monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing the recycled plastic is
A monomer composition for synthesizing recycled plastics, further comprising isophthalic acid having a molar ratio of less than 0.85 mol% based on 100 mol% of the total monomer compounds contained in the monomer composition for synthesizing recycled plastics.
According to claim 1,
Characterized in that the terephthalic acid is recovered from a (co)polymer synthesized from monomers including terephthalic acid used for recovering the monomer composition for synthesizing recycled plastics, the monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing recycled plastics, wherein the terephthalic acid has a molar ratio of greater than 99.15 mol% based on 100 mol% of the total monomer compounds contained in the monomer composition for synthesizing recycled plastics.
According to claim 1,
The monomer composition for synthesizing the recycled plastic is
Further comprising at least one aromatic impurity selected from the group consisting of 4-carboxybenzaldehyde, benzoic acid, and p-toluic acid,
A monomer composition for synthesizing recycled plastics wherein the weight ratio of the aromatic impurities measured by liquid chromatography (LC) is less than 100 ug relative to 1 g of the monomer composition for synthesizing recycled plastics.
According to claim 1,
The (co)polymer synthesized from the monomers including terephthalic acid is recycled, including at least one (co)polymer selected from the group consisting of polyalkylene terephthalate, polyalkylene terephthalate-based copolymer, and thermoplastic polyester elastomer. Monomer composition for plastic synthesis.
Depolymerizing the (co)polymer synthesized from monomers including terephthalic acid and removing the diol component;
washing the depolymerization reaction product from which the diol component has been removed with a solvent at a temperature of 20° C. or more and 100° C. or less; and
Dissolving the washed depolymerization reaction product in water and then recrystallizing it;
The step of recrystallizing the washed depolymerization reaction product after dissolving it in water,
dissolving the washed depolymerization reaction product in water at a temperature of 200 °C to 300 °C; and
Cooling the dissolved solution to a temperature lower than the temperature of the solution by 50 °C to 200 °C;
According to claim 7,
A method for preparing a monomer composition for synthesizing recycled plastic, wherein the solvent in the step of washing the depolymerization reaction product from which the diol component is removed with a solvent at a temperature of 20 ° C to 100 ° C is water.
According to claim 7,
In the washing step,
A method for preparing a monomer composition for synthesizing recycled plastics, using 1 part by weight to 50 parts by weight of a solvent based on 1 part by weight of a (co)polymer synthesized from monomers including terephthalic acid.
According to claim 7,
In the step of dissolving the washed depolymerization reaction product in water at a temperature of 200 ° C to 300 ° C,
A method for preparing a monomer composition for synthesizing recycled plastics, using 1 part by weight to 60 parts by weight of water based on 1 part by weight of a (co)polymer synthesized from monomers including terephthalic acid.
According to claim 7,
The step of dissolving the washed depolymerization reaction product in water at a temperature of 200 ° C to 300 ° C,
Dissolving the washed depolymerization reaction product in water at a temperature of 200 ° C to 220 ° C;
The content of the water is 30 parts by weight to 60 parts by weight based on 1 part by weight of the (co)polymer synthesized from monomers including terephthalic acid, a method for producing a monomer composition for synthesizing recycled plastic.
According to claim 7,
The step of dissolving the washed depolymerization reaction product in water at a temperature of 200 ° C to 300 ° C,
Dissolving the washed depolymerization reaction product in water at a temperature of 240 ° C to 300 ° C;
The content of the water is 1 part by weight to 20 parts by weight based on 1 part by weight of the (co)polymer synthesized from monomers including terephthalic acid. Method for producing a monomer composition for synthesizing recycled plastic.
According to claim 7,
The depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid,
A method for producing a monomer composition for synthesizing recycled plastics, characterized by proceeding by reacting a base in an amount of 2.3 moles or less relative to 1 mole of a (co)polymer synthesized from monomers including terephthalic acid.
According to claim 7,
The depolymerization reaction of the (co)polymer synthesized from the monomers including terephthalic acid,
A method for producing a monomer composition for synthesizing recycled plastics, characterized in that it proceeds in the presence of water or an alkylene glycol solvent.
According to claim 7,
Prior to the step of washing the depolymerization reaction product from which the diol component is removed,
A method for preparing a monomer composition for synthesizing recycled plastics, further comprising a neutralization step of the depolymerization reaction product from which the diol component has been removed with an acid.
A recycled plastic comprising a reaction product of the monomer composition for synthesizing recycled plastic according to claim 1 and a comonomer.
According to claim 16,
The recycled plastic has a yellow index of 50 or less, recycled plastic.
According to claim 16,
The recycled plastic has a color coordinate b* value of 3 or less, recycled plastic.
A molded article comprising the recycled plastic of claim 16.
A plasticizer composition comprising a reaction product of the monomer composition for synthesizing recycled plastic according to claim 1 and an alcohol.