Polyester resin comprising regenerated bis(2-hydroxyethyl)terephthalate, and article comprising polyester resin

Abstract

A polyester resin according to one embodiment comprises regenerated bis(2-hydroxyethyl)terephthalate obtained by means of depolymerization of waste polyester, and the content of acetaldehyde is controlled to be within a predetermined range. The polyester resin according to the embodiment has excellent quality such as heat resistance and color while being polymerized using a regenerated monomer. In addition, provided is an article comprising the polyester resin according to the embodiment.

Description

Polyester resin containing recycled bis(2-hydroxyethyl)terephthalate and articles containing polyester resin

[0001] The present invention relates to a polyester resin comprising recycled bis(2-hydroxyethyl)terephthalate and an article comprising the same.

[0002]

[0003] Polyester boasts excellent mechanical strength, heat resistance, transparency, and gas barrier properties, making it widely used in beverage containers, packaging films, and audio and video films. Polyester is also widely produced worldwide as industrial materials, including medical fibers and tire cords. In particular, polyester sheets and boards, with their excellent transparency and mechanical strength, are widely used in cases, boxes, partitions, shelves, panels, packaging, building materials, and interior and exterior finishes.

[0004] Accordingly, plastic waste, such as polyester, is generated globally at an unmanageable rate each year. Recently, countries around the world are establishing regulations and measures for recycling waste plastic resources, including waste polyester. For example, there is a movement to require a certain percentage of recycled resin in packaging materials used in various fields. While physical and chemical methods are used to recycle waste polyester, physical recycling methods are not widely used due to their inability to guarantee purity.

[0005] Chemical recycling methods depolymerize waste polyester by breaking the ester bonds in the waste polyester. These processes utilize reactions such as glycolysis, hydrolysis, methanolysis, and aminolysis. Among these, glycolysis involves adding a glycol, such as ethylene glycol or diethylene glycol, to waste polyester at high temperatures to decompose it, producing a reaction product that primarily includes bis(2-hydroxyethyl) terephthalate (BHET). Bis(2-hydroxyethyl) terephthalate can be used as a raw material for manufacturing polyester resins after crystallization or purification.

[0006] However, bis(2-hydroxyethyl)terephthalate regenerated in this way may contain by-products generated by side reactions with reagents or solvents used in various chemical steps during depolymerization from waste polyester, and these impurities may remain in trace amounts even after multiple purifications. In particular, acetaldehyde is generated as a side reaction substance during the polycondensation reaction for manufacturing polyester resin, and when polymerization is performed using a regenerated monomer, this side reaction is further aggravated by the impurities, which causes problems in lowering the quality of the polyester resin, such as heat resistance and color.

[0007] Furthermore, thermoplastic polyester resins are widely used in the manufacture of beverage containers due to their low sensitivity to heat and oxygen. However, the byproduct acetaldehyde can alter the flavor of beverages stored in the containers, negatively impacting the taste. Therefore, research is being conducted to adjust raw materials and process conditions to minimize the production of acetaldehyde during the polyester resin manufacturing process.

[0008] [Prior Art Literature]

[0009] (Patent Document 1) Republic of Korea Patent Publication No. 2022-0068991

[0010]

[0011] In the case of recycled polyester resins using monomers such as recycled bis(2-hydroxyethyl)terephthalate, there is a concern that side reactions may increase compared to virgin resins, but no research has been conducted to reduce the generation of acetaldehyde in recycled polyester resins.

[0012] In addition, research has been conducted to reduce the amount of acetaldehyde in polyester resins using new additives, but when adding new additives, the amount of additives must be controlled during the process, and there was a problem of the properties of the produced polyester resin deteriorating.

[0013] Accordingly, the task of the present invention is to provide a polyester resin having excellent qualities such as heat resistance and color by controlling the content of acetaldehyde within a certain range while polymerizing using a regenerated monomer.

[0014]

[0015] According to one aspect of the present invention, a polyester resin is provided, which comprises regenerated bis(2-hydroxyethyl)terephthalate (BHET) obtained by depolymerization of waste polyester and has an acetaldehyde content of 1 ppm or less.

[0016] According to another aspect of the present invention, an article comprising a polyester resin is provided.

[0017]

[0018] The polyester resin according to the present invention contains regenerated bis(2-hydroxyethyl)terephthalate obtained by depolymerization of waste polyester, and has excellent qualities such as heat resistance and color by controlling the content of acetaldehyde within a certain range.

[0019]

[0020] The terms used to refer to each component in this specification are used to distinguish it from other components and are not intended to limit the implementation examples. Furthermore, the singular expressions used in this specification include the plural expressions unless the context clearly dictates otherwise.

[0021] In this specification, the terms "first," "second," etc. are used to describe various components, and the components should not be limited by the terms. The terms are used for the purpose of distinguishing one component from another.

[0022] The word "comprising" or "including" in this specification is intended to specify particular features, regions, steps, processes, elements and / or components, and does not exclude the presence or addition of other features, regions, steps, processes, elements and / or components, unless specifically stated to the contrary.

[0023] The molecular weight of the compound described in this specification or the molecular weight of the polymer, for example, the number average molecular weight or the weight average molecular weight, is a relative mass based on carbon-12, as is well known, and does not specify a unit, but may be understood as a molar mass (g / mol) of the same numerical value, if necessary.

[0024] In this specification, a “derivative” of a specific compound means a compound that is formed by modifying a part of the compound through a chemical reaction or combining it with another component, and that contains a major portion of the compound.

[0025] As used herein, a unit or group "derived" from a specific component refers to a portion of a final product resulting from a chemical reaction, such as a polymerization reaction, in which the component is modified or combined with other components during the reaction process. For example, a chain comprising a polymer may contain units or groups derived from one or more monomers or oligomers.

[0026] In the numerical ranges that limit the size, physical properties, etc. of the components described in this specification, if a numerical range limited only to the upper limit and a numerical range limited only to the lower limit are separately exemplified, it should be understood that a numerical range in which these upper and lower limits are combined is also included in the exemplary range of the present invention.

[0027]

[0028] polyester resin

[0029] According to one aspect of the present invention, a polyester resin is provided, which comprises regenerated bis(2-hydroxyethyl)terephthalate (BHET) obtained by depolymerization of waste polyester and has an acetaldehyde content of 1 ppm or less.

[0030] The polyester resin of the present invention is a polyester resin regenerated through chemical recycling of waste polyester.

[0031] Specifically, since the polyester resin of the present invention is polymerized using recycled BHET, it includes repeating units derived from recycled BHET in the polymer chain.

[0032] The content of recycled BHET in the polyester resin of the present invention may be 1 wt% or more, 5 wt% or more, 10 wt% or more, 30 wt% or more, 50 wt% or more, 70 wt% or more, or 90 wt% or more. In addition, the content of the recycled BHET may be 100 wt% or less, 99 wt% or less, 80 wt% or less, 60 wt% or less, 40 wt% or less, or 20 wt% or less.

[0033] As an example, the recycled bis(2-hydroxyethyl)terephthalate may be included in an amount of 10 wt% to 99 wt% based on the weight of the polyester resin.

[0034] A polyester resin according to one embodiment of the present invention has an acetaldehyde content of 1 ppm or less.

[0035] Specifically, the content of acetaldehyde in the polyester resin may be less than 1 ppm, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.4 ppm or less, 0.3 ppm or less, or 0.2 ppm or less. Meanwhile, the lower limit of the content of acetaldehyde in the polyester resin is not particularly limited, but may be, for example, 0 ppm or more, more than 0 ppm, 0.001 ppm or more, 0.01 ppm or more, or 0.1 ppm or more.

[0036] The above acetaldehyde content may be the content of acetaldehyde based on the weight of the polyester resin (i.e. ppmw).

[0037] The above acetaldehyde is a compound having the chemical formula CH3CHO and is contained in the resin.

[0038] The above acetaldehyde content can be measured, for example, through LC-UV (Liquid chromatography with UV detector). Specifically, a sample is prepared by adding 1 g of polyester resin to 10 mL of an acetonitrile / deionized water mixture (50 / 50 volume ratio), and the acetaldehyde content can be measured through LC-UV. More specifically, the UV-LC can be performed using a UV detector with a wavelength of 363 nm under the following conditions: a column temperature of 35°C, a sample volume of 20 μL, and a flow rate of 0.8 mL / min.

[0039] The polyester resin according to the present invention contains regenerated bis(2-hydroxyethyl)terephthalate obtained by depolymerization of waste polyester, and has excellent qualities such as heat resistance and color by controlling the content of acetaldehyde within a certain range.

[0040] In particular, the color change of the polyester resin is controlled within a certain range even when stored under high temperature and high humidity conditions.

[0041] According to one embodiment, the polyester resin has a △Col-b in the range of -1 to +1 according to the following formula.

[0042] △Col-b = Col-b [10D] - Col-b [0D]

[0043] Here, Col-b [10D] is the b value of the Hunter Lab color space measured after storing the polyester resin at 50°C and 60%RH for 10 days, and Col-b [0D] is the b value of the Hunter Lab color space measured for the polyester resin before storage.

[0044] For example, the above △Col-b may be -1 or more, -0.8 or more, -0.6 or more, -0.4 or more, or -0.2 or more, and may also be 1 or less, 0.8 or less, 0.6 or less, 0.4 or less, or 0.2 or less. Specifically, the above △Col-b may be in the range of -0.8 to 0.8, -0.6 to 0.6, -0.4 to 0.4, or -0.2 to 0.2.

[0045] In addition, according to the present invention, by controlling the content and characteristics of the ethylene glycol component and the recycled BHET component constituting the polyester resin, a polyester resin having improved qualities such as heat resistance can be provided.

[0046] In particular, the heat resistance index of the polyester resin, which is calculated by linking the molar fraction of the ethylene glycol component among the diol components constituting the polyester resin and the characteristics and weight fraction of the recycled BHET component, can be controlled within a specific range.

[0047] According to one embodiment, the resin heat resistance index is calculated using the mole fraction of ethylene glycol among the diol components constituting the polyester resin as a parameter, and the resin heat resistance index can be adjusted within a specific range. The resin heat resistance index is a numerical value related to the content of ethylene glycol constituting the polyester resin, and by adjusting the resin heat resistance index, a decrease in the heat resistance of the polyester resin can be suppressed even when the amount of recycled BHET used is large.

[0048] Specifically, the polyester resin may have a resin heat resistance index of 2.0 or less, calculated by the following formula (Ia).

[0049] Resin heat resistance index = ethylene glycol mole fraction x 0.02 (Ia)

[0050] Here, the ethylene glycol mole fraction is the content (mol%) of the ethylene glycol component based on the total mole number of diol components contained in the polyester resin.

[0051] In the above formula (Ia), only the numerical values ​​excluding the units of the parameters are taken and calculated.

[0052] For example, the resin heat resistance index may be 2.0 or less, 1.8 or less, 1.6 or less, 1.4 or less, 1.2 or less, 1.0 or less, 0.8 or less, or 0.6 or less. In addition, the resin heat resistance index may be 0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more. As a specific example, the first heat resistance index may be 0 to 2.0, or 0.1 to 2.0.

[0053] According to another embodiment, the regenerated heat resistance index is calculated using the characteristics and weight fraction of the regenerated BHET introduced into the polymerization of the polyester resin as parameters, and the regenerated heat resistance index can be controlled within a specific range. The regenerated heat resistance index is a heat resistance index derived from the regenerated BHET introduced into the polymerization of the polyester resin, and when the regenerated heat resistance index is controlled, it can be controlled to have a heat resistance level similar to that of a resin polymerized from virgin monomer.

[0054] Specifically, the polyester resin may have a regenerative heat resistance index of 7.0 or less, calculated by the following formula (Ib).

[0055] Regeneration heat resistance index = (r-BHET TDI) x r-BHET weight fraction x 2 (Ib)

[0056] Here, the r-BHET weight fraction is the content (weight %) of regenerated BHET based on the total weight of the polyester resin, and the r-BHET TDI is defined by the following equation when analyzing the regenerated BHET using high-performance liquid chromatography (HPLC).

[0057] r-BHET TDI = [DEG-ester-1] + [DEG-ester-2] x 2 + exp^[HA-ester]

[0058] Here, DEG-ester-1 is the peak area fraction (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate, DEG-ester-2 is the peak area fraction (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate, and HA-ester is the peak area fraction (%) of 2-hydroxyethyl(2-acetoxyethyl)terephthalate.

[0059] Calculate by taking only the numerical values ​​of these parameters, excluding their units.

[0060] For example, the regenerative heat resistance index may be 7.0 or less, 6.0 or less, 5.0 or less, 4.0 or less, 3.0 or less, 2.0 or less, or 1.0 or less. In addition, the resin heat resistance index may be 0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more. As a specific example, the first heat resistance index may be 0 to 7.0, or 0.1 to 7.0.

[0061] According to another embodiment, a total heat resistance index is calculated using the resin heat resistance index and the regenerated heat resistance index as parameters, and the total heat resistance index can be adjusted within a specific range. Since the total heat resistance index comprehensively considers the quality and amount of regenerated BHET and the ethylene glycol content of the polyester resin, the heat resistance of the polyester resin can be more effectively controlled by adjusting the total heat resistance index.

[0062] Specifically, the polyester resin has a total heat resistance index of 9.0 or less, calculated by the following formula (I).

[0063] Total heat resistance index = resin heat resistance index + recycled heat resistance index (I)

[0064] Here, the resin heat resistance index is calculated using the above formula (Ia), and the regenerative heat resistance index is calculated using the above formula (Ib).

[0065] For example, the total heat resistance index may be 9.0 or less, 8.0 or less, 7.0 or less, 6.0 or less, 5.0 or less, 4.0 or less, 3.0 or less, or 2.0 or less. In addition, the resin heat resistance index may be 0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more. As a specific example, the first heat resistance index may be 0 to 9.0, or 0.1 to 9.0.

[0066] Since the bis(2-hydroxyethyl)terephthalate used in the production of the polyester resin of the present invention has a structure in which two ethylene glycols and one terephthalic acid are combined, the polyester resin of the present invention may include repeating units derived from ethylene glycol and terephthalic acid.

[0067] In this way, the polyester resin of the present invention includes a dicarboxylic acid component and a diol component as monomer components (polymer constituent units) constituting the polyester resin, and these may be derived from bis(2-hydroxyethyl)terephthalate initially introduced for the production of the polyester resin and an additionally introduced monomer.

[0068] The above polyester resin may contain as a constituent at least one comonomer selected from dicarboxylic acids and diols. Accordingly, the polyester resin may be a copolymerized polyester resin.

[0069] For example, the dicarboxylic acid component may additionally include an aromatic dicarboxylic acid component other than terephthalic acid, an aliphatic dicarboxylic acid component, or a mixture thereof. Such a dicarboxylic acid component other than terephthalic acid may be included in an amount of 1 wt% to 30 wt% based on the weight of the entire dicarboxylic acid component.

[0070] The above aromatic dicarboxylic acid component may be an aromatic dicarboxylic acid having 8 to 20 carbon atoms, preferably 8 to 14 carbon atoms, or a mixture thereof. Examples of the above aromatic dicarboxylic acid include, but are not limited to, isophthalic acid, naphthalenedicarboxylic acid such as 2,6-naphthalenedicarboxylic acid, diphenyl dicarboxylic acid, 4,4'-stilbenedicarboxylic acid, 2,5-furandicarboxylic acid, 2,5-thiophenedicarboxylic acid, and the like.

[0071] The aliphatic dicarboxylic acid component may be an aliphatic dicarboxylic acid component having 4 to 20 carbon atoms, preferably 4 to 12 carbon atoms, or a mixture thereof. Examples of the aliphatic dicarboxylic acid include, but are not limited to, linear, branched, or cyclic aliphatic dicarboxylic acid components such as cyclohexanedicarboxylic acid, such as 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid, phthalic acid, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, fumaric acid, adipic acid, glutaric acid, and azelaic acid.

[0072] As a specific example, the dicarboxylic acid may be at least one selected from the group consisting of isophthalic acid, dimethyl isophthalate, phthalic acid, dimethyl phthalate, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate, diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, maleic anhydride, fumaric acid, adipic acid, glutaric acid, and azelaic acid.

[0073] The above diol component may further include a diol component other than the ethylene glycol component as a comonomer. The comonomer may include, for example, at least one selected from the group consisting of diethylene glycol, cyclohexanedimethanol, cyclohexanedimethanol derivatives, and isosorbide.

[0074] The above diethylene glycol can contribute to improving the transparency and impact strength of the polyester resin. For example, the above diethylene glycol can be included in an amount of 0.1 mol% to 50 mol% based on the molar number of the total diol component.

[0075] The above cyclohexanedimethanol (e.g., 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol) can contribute to improving the transparency and impact strength of the polyester resin being manufactured. For example, the cyclohexanedimethanol can be included in an amount of 5 mol% to 90 mol% based on the molar number of the total diol component. The cyclohexanedimethanol derivative can be 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate, or 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol. The cyclohexanedimethanol derivative can be included in an amount of 0.1 mol% to 25 mol% based on the molar number of the total diol component.

[0076] The above isosorbide can improve the processability of the final polyester resin. The transparency and impact strength of the polyester resin are improved by the diol components of cyclohexanedimethanol and ethylene glycol described above. However, for processability, shear flow characteristics must be improved and the crystallization rate must be delayed. However, it is difficult to achieve these effects with cyclohexanedimethanol and ethylene glycol alone. Therefore, when isosorbide is included as a diol component, the processability of the resulting polyester resin can be improved by improving the shear flow characteristics and delaying the crystallization rate while maintaining transparency and impact strength. Preferably, the isosorbide residue may be included in an amount of 0.1 mol% to 70 mol% based on the molar number of the total diol component.

[0077] As a specific example, the diol is isosorbide, neopentylglycol 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate, and It may be at least one selected from the group consisting of 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol.

[0078] In this way, in addition to recycled BHET, a monomer (virgin monomer) generally used in the polymerization of polyester resin can be used in the production of the polyester resin.

[0079] In addition, in the production of the polyester resin, one or more recycled monomers obtained by depolymerization of waste polyester, in addition to recycled BHET, may be used. The recycled monomer may be a monomer obtained by physically or chemically decomposing, depolymerizing, reprocessing, or repolymerizing waste plastics such as waste polyester, or a polymerization raw material containing or derived from the monomer. Such recycled monomers may be obtained directly from waste plastics such as waste polyester by a known method or may be purchased commercially and used.

[0080] As a specific example, the one or more recycled monomers may be selected from the group consisting of recycled dicarboxylic acids, recycled dicarboxylic acid derivatives, recycled diols, and recycled diol derivatives. As a more specific example, the polyester resin may include one or more recycled monomers selected from the group consisting of recycled ethylene glycol, recycled 1,4-cyclohexanedimethanol, recycled diethylene glycol, recycled neopentyl glycol, recycled isosorbide, recycled terephthalic acid, recycled dimethyl terephthalate, recycled isophthalic acid, and recycled dimethyl isophthalate. However, the types of recycled monomers that can be used in the present invention are not limited thereto, and any other recycled monomer that can be introduced into the production of a polyester resin may be used. Such recycled monomers may be included in the polyester resin by completely replacing virgin monomers, or the recycled monomers and virgin monomers may be included together in the polyester resin at a certain ratio.

[0081] The polyester resin may also include a catalyst used in the polymerization reaction for its manufacture. For example, the polyester resin may include at least one catalyst selected from a metal oxide or acetate. The metal included in the catalyst may be selected from the group consisting of antimony (Sb), titanium (Ti), germanium (Ge), manganese (Mn), cobalt (Co), tin (Sn), and calcium (Ca).

[0082]

[0083] Regenerated bis(2-hydroxyethyl)terephthalate

[0084] The polyester resin according to the present invention comprises recycled bis(2-hydroxyethyl)terephthalate (BHET).

[0085] Bis(2-hydroxyethyl)terephthalate (BHET) is an ester of two ethylene glycols and one terephthalic acid, and is a compound formed as an intermediate in the process of producing polyesters such as polyethylene terephthalate (PET) through a polymerization reaction between ethylene glycol and terephthalic acid or an ester thereof.

[0086] Meanwhile, bis(2-hydroxyethyl) terephthalate (recycled BHET), regenerated through depolymerization of waste polyester, contains byproducts generated by reagents or solvents used in the various chemical steps of depolymerization from waste polyester, or by side reactions with these reagents. Therefore, BHET regenerated through conventional depolymerization methods often contains organic and inorganic impurities in addition to the main component, BHET, and thus has a low purity.

[0087] However, the recycled bis(2-hydroxyethyl)terephthalate used in the production of the polyester resin of the present invention is obtained by depolymerization of waste polyester, and has excellent purity and quality.

[0088] The purity of the above-mentioned regenerated BHET can be measured using liquid chromatography, etc. Specifically, the purity of the above-mentioned regenerated BHET can be derived by measuring the fraction (%) of the BHET peak area among the total peak area in a spectrum obtained using high-performance liquid chromatography (HPLC).

[0089] The above-mentioned recycled bis(2-hydroxyethyl)terephthalate may have a peak area fraction of bis(2-hydroxyethyl)terephthalate of 95% or more when analyzed by high-performance liquid chromatography (HPLC). For example, the peak area fraction of bis(2-hydroxyethyl)terephthalate may be 95% or more, 97% or more, 98% or more, 99% or more, or 99.5% or more, and specifically, may be 95% to 100%, or 97% to 100%.

[0090] Meanwhile, the above-mentioned regenerated bis(2-hydroxyethyl)terephthalate may include compounds other than BHET, specifically BHET analogs and BHET oligomers (e.g., dimers, trimers), as well as other esters, acetates, etc.

[0091] Specifically, the above-mentioned regenerated bis(2-hydroxyethyl)terephthalate may have a peak area fraction of dimer or higher oligomers of 2.0% or less in total when analyzed by high-performance liquid chromatography (HPLC). More specifically, the peak area fraction of dimer or higher oligomers may be 1.5% or less, 1.0% or less, or 0.5% or less.

[0092] Generally, bis(2-hydroxyethyl)terephthalate regenerated through depolymerization of waste polyester resin contains oligomer substances such as dimers and trimers, as well as byproducts derived from diethylene glycol (DEG) generated at high depolymerization temperatures, which are factors that lower the quality of the product.

[0093] In addition, acetate (e.g., zinc acetate), which is mainly used as a catalyst in the glycolysis reaction, reacts with ethylene glycol during the depolymerization reaction and is converted into hydroxyethyl acetate (HA). Since the HA has a similar boiling point to ethylene glycol, which is mainly used as a solvent, it is not easily filtered out as an impurity during the recovery and reuse of ethylene glycol, and as a result, by-products accumulate as the process is repeated.

[0094] As shown in the reaction scheme 1 below, acetic acid (AcOH), derived from metal acetate, which is mainly used as a catalyst, can react with ethylene glycol (EG) to produce an acetate compound such as 2-hydroxyethyl acetate (HA) and water (H2O).

[0095]

[0096] In addition, as shown in the reaction scheme 2 below, 2-hydroxyethyl acetate (HA) can produce ester compounds such as 2-hydroxyethyl (2-acetoxyethyl) terephthalate (HAET, 2-hydroxyethyl (2-acetoxyethyl) terephthalate) and ethylene glycol (EG) through an ester exchange reaction with bis(2-hydroxyethyl) terephthalate (BHET).

[0097]

[0098] According to one embodiment, the recycled bis(2-hydroxyethyl)terephthalate has a peak area fraction of an acetate-based ester compound of 1.0% or less when analyzed by high-performance liquid chromatography (HPLC). Specifically, the recycled bis(2-hydroxyethyl)terephthalate may have a peak area fraction of an acetate-based ester compound of 0.7% or less, 0.5% or less, 0.3% or less, or 0.2% or less when analyzed by high-performance liquid chromatography (HPLC). Meanwhile, the lower limit of the peak area fraction of the acetate-based ester compound is not particularly limited, but may be, for example, 0% or more, 0.001% or more, 0.01% or more, or 0.1% or more. The above acetate-based ester compound may be a 2-hydroxyethyl acetate ester compound, and specifically may include at least one selected from the group consisting of 2-hydroxyethyl(2-acetoxyethyl)terephthalate (HAET), 2-acetoxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate, and 2-hydroxyethyl[2-[2-(2-hydroxyethoxy)ethoxy]ethyl]terephthalate. As a more specific example, the acetate-based ester compound may include 2-hydroxyethyl(2-acetoxyethyl)terephthalate.

[0099] In addition, the recycled bis(2-hydroxyethyl)terephthalate has a peak area fraction of a diethylene glycol (DEG) ester compound of a total of 2.0% or less when analyzed by high-performance liquid chromatography (HPLC). For example, the peak area fraction of the diethylene glycol (DEG) ester compound may be a total of 1.5% or less, 1% or less, or 0.5% or less. Meanwhile, the lower limit of the peak area fraction of the diethylene glycol (DEG) ester compound is not particularly limited, but may be, for example, a total of 0% or more, 0.001% or more, 0.01% or more, or 0.1% or more. The above diethylene glycol ester compound may include 2-hydroxyethyl [2-(2-hydroxyethoxy)ethyl] terephthalate and bis[2-(2-hydroxyethoxy)ethyl] benzene-1,4-dicarboxylate. These are represented by the chemical formulae 1 and 2 below, respectively.

[0100]

[0101] In one embodiment, the recycled bis(2-hydroxyethyl)terephthalate (BHET) has a peak area fraction of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate (first diethylene glycol ester) of 2.5% or less as measured by high performance liquid chromatography (HPLC). Specifically, the peak area fraction of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate as measured by HPLC may be 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less.

[0102] In another embodiment, the recycled bis(2-hydroxyethyl)terephthalate (BHET) has a peak area fraction of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate (second diethylene glycol ester) of 0.5% or less as measured by high performance liquid chromatography (HPLC). Specifically, the HPLC peak area fraction of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate as measured by HPLC may be 0.2% or less, and more specifically, 0.15% or less, 0.1% or less, or 0.05% or less.

[0103] The present invention can prevent the heat resistance characteristics of a recycled polyester resin from being lowered by these compounds during polymerization by controlling the content of an acetate-based ester compound and a diethylene glycol ester compound in a recycled bis(2-hydroxyethyl) terephthalate to a specific level.

[0104] As the content of the diethylene glycol ester compound in the recycled bis(2-hydroxyethyl) terephthalate increases, the heat resistance properties, such as the melting point, of the final polymer resin decrease linearly, and the acetate ester compound acts as a terminator that inhibits the growth of the polymer chain, so that as the content thereof increases, the heat resistance properties of the final polymer resin decrease exponentially. Therefore, using this relationship, an equation for predicting the heat resistance properties of a polymer resin manufactured from recycled bis(2-hydroxyethyl) terephthalate can be derived.

[0105] For example, the above-mentioned recycled bis(2-hydroxyethyl)terephthalate may have a thermal property drop index (TDI) defined by the following equation when analyzed by high-performance liquid chromatography (HPLC) of 6.0 or less, 5.0 or less, or 4.0 or less, and specifically, may be 3.0 or less.

[0106] r-BHET TDI = [DEG-ester-1] + [DEG-ester-2] x 2 + exp^[HA-ester]

[0107] Here, DEG-ester-1 is the peak area fraction (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate, DEG-ester-2 is the peak area fraction (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate, and HA-ester is the peak area fraction (%) of 2-hydroxyethyl(2-acetoxyethyl)terephthalate, and the calculation is performed by taking only the numerical values ​​excluding the units of these parameters.

[0108] Specifically, when the thermal degradation index (TDI) defined by the above formula is 3.0 or less, the heat resistance properties of the recycled polyester resin can be more effectively prevented from being deteriorated by these compounds during polymerization. More specifically, the thermal degradation index (TDI) may be 2.5 or less, or 2.0 or less. Alternatively, the thermal degradation index (TDI) may be 0 to 3.0, 0 to 2.5, 0.5 to 3.0, 1.0 to 3.0, or 0.5 to 2.5.

[0109] Additionally, the above-mentioned regenerated bis(2-hydroxyethyl)terephthalate may have a peak area fraction of monohydroxyethyl terephthalate (MHET) of 2% or less, 1.5% or less, 1% or less, or 0.5% or less when analyzed by high-performance liquid chromatography (HPLC).

[0110] In addition, the total content of residual ethylene glycol in the recycled bis(2-hydroxyethyl)terephthalate may be 1 wt% or less, 0.9 wt% or less, 0.5 wt% or less, or 0.3 wt% or less, based on the weight ratio detected by gas chromatography analysis. Specifically, the content of residual ethylene glycol in the recycled bis(2-hydroxyethyl)terephthalate may be 0.5 wt% or less. More specifically, the content of residual ethylene glycol in the recycled bis(2-hydroxyethyl)terephthalate may be 0.2 wt% or less, 0.15 wt% or less, or 0.1 wt% or less.

[0111] In this way, the bis(2-hydroxyethyl)terephthalate used in the production of the polyester resin of the present invention has high purity and a low content of impurities such as diethylene glycol ester, even though it is a regenerated monomer obtained by depolymerization of waste polyester.

[0112] According to one embodiment, a method for producing recycled bis(2-hydroxyethyl)terephthalate comprises the steps of (a) depolymerizing waste polyester by glycolysis to obtain a crude bis(2-hydroxyethyl)terephthalate solution; (b) cooling the crude bis(2-hydroxyethyl)terephthalate solution to crystallize it; and (c) separating the crystallized product into solid and liquid using a pressure filter.

[0113] Specifically, the depolymerization in step (a) may include (1) depolymerizing the waste polyester by a first glycolysis reaction at a temperature of 180°C to 200°C to obtain a first reactant; and (2) depolymerizing the first reactant by a second glycolysis reaction at a temperature of 150°C to 170°C to obtain a second reactant.

[0114] In addition, in the above step (c), the pressurized filter may be a Nutsche filter or a filter press. In addition, in the above step (c), acetate compounds and diethylene glycol compounds may be removed by the pressurized filter.

[0115] The above-mentioned regenerated bis(2-hydroxyethyl)terephthalate can be manufactured by further performing a step of removing unreacted glycol by distillation.

[0116] In addition, the above-mentioned regenerated bis(2-hydroxyethyl)terephthalate can be manufactured by further performing at least one of the steps of thin-film distillation under reduced pressure; and the steps of dissolving in water and adsorption-crystallization.

[0117] In this way, by removing low-weight organic substances including acetic acid through cooling crystallization and pressurized filtering during the purification process, the content of by-products such as acetate ester compounds or diethylene glycol ester compounds can be effectively controlled.

[0118]

[0119] Method for manufacturing polyester resin

[0120] A method for producing a polyester resin according to the present invention includes a step of polymerizing a polyester resin using recycled bis(2-hydroxyethyl)terephthalate obtained by depolymerizing waste polyester.

[0121] The polyester resin according to the present invention can be manufactured by further adding terephthalic acid or a derivative thereof and / or ethylene glycol in addition to the above-described regenerated bis(2-hydroxyethyl)terephthalate. In addition, the polyester resin can be manufactured into a copolymer by further adding a comonomer selected from other dicarboxylic acids and / or diols.

[0122] The above polymerization can be performed sequentially by performing an esterification reaction (step 1) and a condensation polymerization reaction (step 2).

[0123] The above esterification reaction can be carried out in the presence of an esterification reaction catalyst, for example, a zinc-based catalyst can be used. Specific examples of such zinc-based catalysts include zinc acetate, zinc acetate hydrate, zinc chloride, zinc sulfate, zinc sulfide, zinc carbonate, zinc citrate, zinc gluconate, or mixtures thereof.

[0124] The above esterification reaction can be carried out, for example, at a pressure of 0 kg / cm2 to 10.0 kg / cm2 and a temperature of 150°C to 300°C. The esterification reaction conditions can be appropriately adjusted depending on the specific characteristics of the polyester to be produced, the ratio of each component, or process conditions. Specifically, the pressure in the esterification reaction can be 0 kg / cm2 to 5.0 kg / cm2, more specifically 0.1 kg / cm2 to 3.0 kg / cm2. In addition, the temperature in the esterification reaction can be 200°C to 270°C, more specifically 240°C to 260°C.

[0125] The above esterification reaction can be carried out in batch or continuous manner, and each raw material can be input separately, but it is preferable to input it in the form of a slurry in which the diol component is mixed with the dicarboxylic acid component and the recycled BHET. In addition, the diol component such as isosorbide, which is a solid at room temperature, can be dissolved in water or ethylene glycol and then mixed with the dicarboxylic acid component such as terephthalic acid to make a slurry. Alternatively, after isosorbide is melted at 60°C or higher, the dicarboxylic acid component such as terephthalic acid and other diol components can be mixed to make a slurry. In addition, water can be additionally added to the mixed slurry to help increase the fluidity of the slurry.

[0126] The polycondensation reaction can be carried out, for example, by reacting the esterification reaction product at a temperature of 150°C to 300°C and a reduced pressure of 0.01 mmHg to 600 mmHg for 1 to 24 hours. The polycondensation reaction can produce a polyester resin having a relatively low molecular weight through melt polymerization, and can also produce a polyester resin having a relatively high molecular weight through solid-state polymerization after melt polymerization.

[0127] In the above polycondensation reaction, the temperature may be 150°C to 300°C, specifically 200°C to 290°C, and more specifically 260°C to 280°C. In addition, the pressure in the polycondensation reaction may be 0.01 mmHg to 600 mmHg, specifically 0.05 mmHg to 200 mmHg, and more specifically 0.1 mmHg to 100 mmHg. By applying the reduced pressure condition of the polycondensation reaction, the glycol, which is a by-product of the polycondensation reaction, can be removed from the system, and if the pressure in the polycondensation reaction exceeds 0.01 mmHg to 600 mmHg, the removal of the by-product may be insufficient. In addition, if the temperature in the polycondensation reaction is lower than 150°C, the reaction byproduct glycol cannot be effectively removed from the system, which may lower the intrinsic viscosity of the final reaction product and deteriorate the physical properties of the final polyester resin. In addition, if the temperature in the polycondensation reaction exceeds 300°C, the possibility of yellowing occurring in the final polyester resin increases. In addition, the polycondensation reaction may proceed for a necessary time until the intrinsic viscosity of the final reaction product reaches an appropriate level, for example, for an average residence time of 1 to 24 hours.

[0128] In addition, the polycondensation reaction may be carried out in the presence of a polycondensation catalyst, and the polycondensation catalyst may be, for example, a titanium-based compound, a germanium-based compound, an antimony-based compound, an aluminum-based compound, a tin-based compound, or a mixture thereof. Examples of the titanium-based compound include tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, 2-ethylhexyl titanate, octylene glycol titanate, lactate titanate, triethanolamine titanate, acetylacetonate titanate, ethylacetoacetic ester titanate, isostearyl titanate, titanium dioxide, and the like. Examples of the germanium-based compound include germanium dioxide, germanium tetrachloride, germanium ethyleneglycoxide, germanium acetate, or a mixture thereof. Preferably, germanium dioxide may be used, and the germanium dioxide may be either crystalline or amorphous, and may also be glycol-soluble. The amount of the polycondensation catalyst may be used so that the amount of titanium element relative to the weight of the polyester resin is about 1 to 100 ppm, more preferably about 1 to 50 ppm.

[0129] In addition to the above polycondensation catalyst, stabilizers, coloring agents, crystallizers, antioxidants, branching agents, etc. may be further used, and the timing of adding these additives is not particularly limited and may be added at any time during the manufacturing stage of the polyester resin.

[0130] As the above stabilizer, phosphorus compounds such as phosphoric acid, trimethyl phosphate, triethyl phosphate, and triethylphosphonoacetate can be generally used, and the amount added can be 10 to 200 ppm based on the amount of phosphorus element relative to the weight of the polyester resin. In addition, as a coloring agent added to improve the color of the polyester resin, typical coloring agents such as cobalt acetate and cobalt propionate can be exemplified, and the amount added can be 10 to 200 ppm based on the amount of cobalt element relative to the weight of the polyester resin. If necessary, anthraquinone compounds, perinone compounds, azo compounds, methine compounds, etc. can be used as an organic compound coloring agent, and commercially available products include toners such as Polysynthren Blue RLS from Clarient or Solvaperm Red BB from Clarient. The amount of the organic compound coloring agent added can be adjusted to 0 to 50 ppm based on the weight of the polyester resin. Examples of the crystallizer include a crystal nucleating agent, an ultraviolet absorber, a polyolefin resin, a polyamide resin, and the like. Examples of the antioxidant include a hindered phenol antioxidant, a phosphite antioxidant, a thioether antioxidant, or a mixture thereof. Examples of the branching agent include a typical branching agent having three or more functional groups, such as trimellitic anhydride, trimethylol propane, trimellitic acid, or a mixture thereof.

[0131] The intrinsic viscosity (IV) of the polyester resin may be 0.5 dl / g or more, 0.6 dl / g or more, or 0.7 dl / g or more at 35°C, and may also be 1.2 dl / g or less, 1.1 dl / g or less, 1.0 dl / g or less, or 0.9 dl / g or less. For example, the intrinsic viscosity of the polyester resin may be 0.5 dl / g to 1.2 dl / g at 35°C. Specifically, the intrinsic viscosity may be measured by dissolving the polyester resin in orthochlorophenol (OCP) at 100°C at a concentration of 0.12% and then using an Ubbelrod-type viscometer in a constant temperature bath at 35°C.

[0132] The polyester resin according to the present invention comprises recycled bis(2-hydroxyethyl) terephthalate obtained by depolymerizing waste polyester, and has excellent qualities such as heat resistance and color since the content of acetaldehyde is controlled within a certain range. Specifically, acetaldehyde is generated as a side reaction product during a polycondensation reaction for producing a polyester resin, and if an acetate-based ester compound is present in the recycled bis(2-hydroxyethyl) terephthalate, the production of such acetaldehyde may increase during the polycondensation process. However, since the polyester resin of the present invention is produced using recycled bis(2-hydroxyethyl) terephthalate in which the content of the acetate-based ester compound, etc., is controlled, the production of acetaldehyde during the polycondensation process can be suppressed.

[0133] The polyester resin according to the present invention can be used in the manufacture of products in various fields because it has excellent qualities such as heat resistance and color.

[0134] Accordingly, the present invention provides an article comprising the polyester resin described above. For example, the article may be a container, a blown article, a film, a sheet, or a profile.

[0135] Specific examples of the above containers include cosmetic containers and food containers.

[0136] The above blow refers to a material for obtaining a hollow plastic molded product through blow molding, and specific examples include injection blow and extrusion blow.

[0137] Specific examples of the above films include heat-shrinkable films and blown films.

[0138] The above profile means a continuous extrusion molded product of plastic excluding sheets and films, which can be manufactured by a general extrusion molding method and can have a shape such as a tube or channel, for example.

[0139]

[0140] Hereinafter, preferred examples are presented to aid in understanding the present invention. However, the following examples are provided solely to facilitate a better understanding of the present invention and are not intended to limit the scope of the present invention.

[0141]

[0142] <Manufacturing of Regenerated BHET>

[0143]

[0144] Manufacturing example: r-BHET A1

[0145] 1000 g of waste polyester resin, 2000 g of ethylene glycol, and 5.0 g of zinc acetate anhydride were charged into a first stainless steel (SUS) reactor, and the internal temperature of the reactor was raised to 180°C to conduct depolymerization (first glycolysis reaction) for 2 hours. The obtained reactant (first reactant) was transferred to a second reactor and cooled to 150°C, and then 2000 g of ethylene glycol was additionally charged, and depolymerization (second glycolysis reaction) was conducted for 2 hours while maintaining the reactor temperature at 150°C.

[0146] The obtained reactant (second reactant) was cooled to 120°C through a reduced pressure flash and then filtered through a Celite TM545) 16 g was added and pressure filtration was performed to perform solid-liquid separation. The separated liquid reactant was passed through a column filled with ion exchange resin (BC107(H) from Bonlite) to remove ionic impurities, thereby obtaining a mixture (third reactant) containing bis(2-hydroxyethyl) terephthalate and ethylene glycol.

[0147] The above mixture (third reactant) was cooled to room temperature over 2 hours under stirring at 100 RPM in a 10 L jacket-type cooling water circulation crystallizer, and the obtained crystal product was filtered through a pressurized Nutsche filter (jacket-type, filtration area 0.2 m 2 ) was used to separate solid and liquid under pressure conditions of 3 bar to obtain BHET cake (fourth reactant).

[0148] After transferring the above BHET cake to a 10 L distillation apparatus, the temperature was re-increased to 130°C, and stepwise reduced pressure distillation was performed under reduced pressure conditions from 760 torr to 0.8 torr to recover unreacted ethylene glycol. The reactant (the fifth reactant) from which ethylene glycol was removed was subjected to thin-film distillation in a thin-film distiller (VTA VKL70-4S) at 220°C and 0.08 Torr to remove oligomers higher than dimers, obtaining 1040 g of the product. Afterwards, 1040 g of the above product and 3120 g of distilled water were placed in a 10 L glass reactor for adsorption-crystallization, dissolved at a temperature of 70°C, and 5.2 g of activated carbon was added, stirred for 30 minutes, and filtered. The filtrate was cooled to room temperature to crystallize, filtered, and dried in a vacuum oven. As a result, 1980 g of recycled bis(2-hydroxyethyl)terephthalate was obtained.

[0149]

[0150] Manufacturing example: r-BHET A2

[0151] The procedure of the manufacturing example of r-BHET A1 was repeated, but the progress time of the first glycolysis reaction was adjusted to 1 hour, thereby obtaining regenerated bis(2-hydroxyethyl)terephthalate.

[0152]

[0153] Manufacturing example: r-BHET A3

[0154] Repeat the procedure of the manufacturing example of r-BHET A1, but use a filter press (filtration area 0.4 m) instead of the pressurized Nutche filter. 2 , 4 filter plates) was used to obtain regenerated bis(2-hydroxyethyl)terephthalate by filtration under 18 bar pressure conditions.

[0155]

[0156] Manufacturing example: r-BHET A4

[0157] The procedure of the manufacturing example of r-BHET A1 was repeated, but waste polyester fiber was used as the waste polyester resin, to obtain regenerated bis(2-hydroxyethyl)terephthalate.

[0158]

[0159] Manufacturing example: r-BHET A5

[0160] The procedure of the preparation example of r-BHET A1 was repeated, but without performing adsorption-crystallization after thin film distillation, and regenerated bis(2-hydroxyethyl)terephthalate was obtained.

[0161]

[0162] Manufacturing example: r-BHET A6

[0163] The same procedure as in the preparation example of r-BHET A4 was repeated to obtain regenerated bis(2-hydroxyethyl)terephthalate.

[0164]

[0165] Manufacturing example: r-BHET A7

[0166] The same procedure as in the preparation example of r-BHET A1 was repeated to obtain regenerated bis(2-hydroxyethyl)terephthalate.

[0167]

[0168] Manufacturing example: r-BHET B1

[0169] The procedure of the manufacturing example of r-BHET A1 was repeated, but the temperature at the time of the first glycolysis reaction was adjusted to 210°C, and the temperature at the time of the second glycolysis reaction was adjusted to 250°C, thereby obtaining regenerated bis(2-hydroxyethyl)terephthalate.

[0170]

[0171] Manufacturing example: r-BHET B2

[0172] The procedure of the manufacturing example of r-BHET A1 was repeated, but the cooling crystallization and pressurized Nutsche filter processes were omitted, thereby obtaining regenerated bis(2-hydroxyethyl)terephthalate.

[0173]

[0174] Exam example

[0175]

[0176] (1) High-performance liquid chromatography (HPLC)

[0177] Approximately 0.01 g of recycled bis(2-hydroxyethyl)terephthalate was diluted in approximately 20 mL of methanol and analyzed by high-performance liquid chromatography (HPLC) (Model: Waters e2695, Column: C18 (4.6 x 250 mm), 5 μm, UV Detector: 242 nm, Injection volume: 10 μL, Eluent (Gradient) A: H2O+H3PO4, B: Acetonitrile). Afterwards, the peak area fraction (%) of the following components among the total peak area of ​​HPLC was obtained.

[0178] - MHET: Monohydroxyethyl terephthalate

[0179] - BHET: bis(2-hydroxyethyl) terephthalate

[0180] - DEG-ester-1: 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate

[0181] - DEG-ester-2: Bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate

[0182] - HA-ester: 2-hydroxyethyl (2-acetoxyethyl) terephthalate

[0183] - Dimer: BHET dimer

[0184] - Trimer: BHET trimer

[0185]

[0186] (2) Gas chromatography (GC)

[0187] 0.1 g of regenerated bis(2-hydroxyethyl)terephthalate was dissolved in 10 mL CHCl3, filtered through a 0.45 μm filter, and measured by GC.

[0188] - Model: Agilent 7890B

[0189] - Column: DB-624 (30 mx 0.25 mm x 1.4 ㎛)

[0190] - Oven Temp.: 60℃(2 min)-10℃ / min-200℃(0 min)-20℃ / min-260℃(5 min)

[0191] - Injector Temp.: 250℃

[0192] - Detector Temp.: 250℃

[0193] - Flow: 1.5 mL / min (N2), Split ratio: 1 / 50

[0194]

[0195] (3) TDI

[0196] HPLC analysis was performed on the recycled bis(2-hydroxyethyl)terephthalate using the method (1) above, and the thermal property drop index (TDI) defined by the following equation was calculated.

[0197] TDI = [DEG-ester-1] + [DEG-ester-2] x 2 + exp^[HA-ester]

[0198] Here, DEG-ester-1 is the peak area fraction (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate, DEG-ester-2 is the peak area fraction (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate, and HA-ester is the peak area fraction (%) of 2-hydroxyethyl(2-acetoxyethyl)terephthalate, and the calculation is performed by taking only the numerical values ​​excluding the units of these parameters.

[0199]

[0200] The results are shown in the table below.

[0201] Item r-BHETA1A2A3A4A5A6A7HPLC(%)BHET98.2198.1098.5197.2296.2197.2298.21MHET0.781.100.671.701.721.700.78DEG-ester-10.410.320.220.440.800.440.41DEG-ester-20.040. 020.200.080.120.080.04HA-ester0.200.210.110.230.410.230.20dimer0.210.200.340.280.220.280.21trimer0.010.000.000.010.050.010.01Other0.150.050.130.040.470.040.15GC (wt%)residue EG0.100.100.100.100.200.200.07TDI1.711.591.741.862.551.861.71

[0202] Item r-BHETB1B2HPLC(%)BHET90.0491.20MHET1.822.14DEG-ester-15.201.85DEG-ester-21.320.98HA-ester0.331.12dimer0.220.79trimer0.900.70Other0.171.22GC(wt%)ResidueEG0.220.23TDI9.236.87

[0203]

[0204] <Manufacturing of polyester resin>

[0205]

[0206] Example 1

[0207] Into a reactor connected to a column and a condenser capable of being cooled by water, 6273.5 g of regenerated bis(2-hydroxyethyl) terephthalate (r-BHET A1), 4100.0 g of terephthalic acid (TPA), 612.5 g of ethylene glycol (EG), 1067.0 g of 1,4-cyclohexanedimethanol (CHDM), 288.5 g of isosorbide (ISB), 72.1 g of diethylene glycol (DEG), 0.4 g of Ti catalyst, 10.0 g of phosphoric acid, 0.010 g of blue toner, and 0.005 g of red toner were charged.

[0208] Next, nitrogen was injected into the reactor so that the pressure of the reactor was 1.0 kgf / cm above atmospheric pressure. 2 It was pressurized to a high degree (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was increased to 220℃ over 90 minutes, maintained at 220℃ for 2 hours, and then increased to 260℃ over 2 hours. Then, the mixture inside the reactor was observed with the naked eye, and the esterification reaction was carried out while maintaining the temperature of the reactor at 260℃ until the mixture became transparent. During this process, by-products were discharged through the column and condenser. When the esterification reaction was completed, the nitrogen inside the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and the mixture inside the reactor was transferred to a reactor capable of vacuum reaction.

[0209] Then, the pressure of the reactor was lowered from atmospheric pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was raised to 265°C over 1 hour. While maintaining the pressure of the reactor below 1 Torr (absolute pressure: 1 mmHg), the polycondensation reaction was performed. In the early stage of the polycondensation reaction, the stirring speed was set fast, but as the polycondensation reaction progresses, if the stirring force becomes weak due to the increase in the viscosity of the reactants or the temperature of the reactants rises above the set temperature, the stirring speed can be appropriately adjusted. The polycondensation reaction was performed until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.70 dl / g. When the intrinsic viscosity of the mixture inside the reactor reached the desired level, the mixture was discharged outside the reactor to be stranded, which was solidified with a cooling liquid and then granulated to an average weight of about 12 to 14 mg.

[0210] The particles were left at 150°C for 1 hour to crystallize, then placed in a solid-state polymerization reactor, and while flowing nitrogen at a rate of 50 L / min, the temperature of the reactor was increased from room temperature to 200°C at a rate of 40°C / hour, and maintained at this temperature until the intrinsic viscosity (IV) of the particles in the reactor became 1.00 dl / g, thereby obtaining approximately 10 kg of polyester resin.

[0211]

[0212] Example 2

[0213] The same procedure as Example 1 was repeated, but 11936.1 g of regenerated bis(2-hydroxyethyl)terephthalate (r-BHET A2), 1353.4 g of 1,4-cyclohexanedimethanol (CHDM), 137.2 g of diethylene glycol (DEG), 6.4 g of Ge catalyst, 0.030 g of blue toner, and 0.015 g of red toner were added, and the esterification reaction was carried out at 2.0 kgf / cm above atmospheric pressure. 2The polycondensation reaction was carried out at a high pressure and temperature of 260°C, and the polycondensation reaction was carried out at a temperature of 275°C until the intrinsic viscosity (IV) became 0.65 dl / g, and then about 10 kg of polyester resin was obtained without carrying out solid-state polymerization.

[0214]

[0215] Example 3

[0216] The same procedure as in Example 1 was repeated, but 8472.8 g of regenerated bis(2-hydroxyethyl)terephthalate (r-BHET A3), 2373.1 g of terephthalic acid (TPA), 177.3 g of ethylene glycol (EG), 960.7 g of 1,4-cyclohexanedimethanol (CHDM), 347.9 g of diethylene glycol (DEG), 347.9 g of CHDM derivative (containing 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate and 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol in a molar ratio of 1:3), 6.4 g of Ge catalyst, 0.5 g of Ti catalyst, 0.040 g of blue toner, and 0.010 g of red toner were added, and esterification Reaction 0.5 kgf / cm above atmospheric pressure 2 The polycondensation reaction was carried out at a high pressure and temperature of 260°C, and the polycondensation reaction was carried out at a temperature of 275°C until the intrinsic viscosity (IV) became 0.75 dl / g, and then about 10 kg of polyester resin was obtained without carrying out solid-state polymerization.

[0217]

[0218] Example 4

[0219] The same procedure as in Example 1 was repeated, but 2220.3 g of regenerated bis(2-hydroxyethyl) terephthalate (r-BHET A4), 5804.2 g of terephthalic acid (TPA), 9.0 g of ethylene glycol (EG), 3776.2 g of 1,4-cyclohexanedimethanol (CHDM), 1701.6 g of isosorbide (ISB), 319.1 g of diethylene glycol (DEG), 0.4 g of Ti catalyst, 3.0 g of phosphoric acid, 0.015 g of blue toner, and 0.005 g of red toner were added, and the esterification reaction was carried out at a pressure of 1 kgf / cm above atmospheric pressure. 2 The polycondensation reaction was carried out at a high pressure and temperature of 265°C, and the polycondensation reaction was carried out at a temperature of 280°C until the intrinsic viscosity (IV) became 0.75 dl / g, and then about 10 kg of polyester resin was obtained without carrying out solid-state polymerization.

[0220]

[0221] Example 5

[0222] The same procedure as in Example 1 was repeated, but 4739.6 g of regenerated bis(2-hydroxyethyl)terephthalate (r-BHET A5), 4646.3 g of terephthalic acid (TPA), 1793.2 g of ethylene glycol (EG), 1679.4 g of 1,4-cyclohexanedimethanol (CHDM), 204.3 g of CHDM derivative (containing 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate and 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol in a molar ratio of 1:3), 12.8 g of Ge catalyst, 0.9 g of Ti catalyst, 0.006 g of blue toner, and 0.002 g of red toner were added, and the esterification reaction was carried out at a pressure of 2 kgf / cm2 below atmospheric pressure. 2 The polycondensation reaction was carried out at a high pressure and temperature of 255°C, and the polycondensation reaction was carried out at a temperature of 285°C until the intrinsic viscosity (IV) became 0.80 dl / g, and then about 10 kg of polyester resin was obtained without carrying out solid-state polymerization.

[0223]

[0224] Example 6

[0225] The same procedure as in Example 1 was repeated, but 12510.4 g of regenerated bis(2-hydroxyethyl)terephthalate (r-BHET A6), 430.3 g of terephthalic acid (TPA), 225.0 g of ethylene glycol (EG), 227.1 g of CHDM derivative (containing 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate and 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol in a molar ratio of 1:3), 12.8 g of Ge catalyst, 0.9 g of Ti catalyst, 0.006 g of blue toner, and 0.002 g of red toner were added, and the esterification reaction was carried out at a pressure of 2 kgf / cm2 below atmospheric pressure. 2 The polycondensation reaction was carried out at a high pressure and temperature of 255°C, and the polycondensation reaction was carried out at a temperature of 285°C until the intrinsic viscosity (IV) became 0.80 dl / g, and then about 10 kg of polyester resin was obtained without carrying out solid-state polymerization.

[0226]

[0227] Example 7

[0228] The same procedure as in Example 1 was repeated, but 8660.5 g of regenerated bis(2-hydroxyethyl) terephthalate (r-BHET A7), 2425.7 g of terephthalic acid (TPA), 5660.0 g of isophthalic acid (IPA), 100.7 g of ethylene glycol (EG), 1402.8 g of 1,4-cyclohexanedimethanol (CHDM), 474.1 g of isosorbide (ISB), 355.6 g of diethylene glycol (DEG), 0.9 g of Ti catalyst, 1.0 g of phosphoric acid, 0.020 g of blue toner, and 0.010 g of red toner were added, and the esterification reaction was carried out at a pressure of 3 kgf / cm above atmospheric pressure. 2 The polycondensation reaction was carried out at a high pressure and temperature of 260°C, and the polycondensation reaction was carried out at a temperature of 275°C until the intrinsic viscosity (IV) became 0.65 dl / g, and then about 10 kg of polyester resin was obtained without carrying out solid-state polymerization.

[0229]

[0230] Comparative Example 1

[0231] The same procedure as Example 1 was repeated, but 5968.0 g of regenerated bis(2-hydroxyethyl) terephthalate (r-BHET B1), 3900.4 g of terephthalic acid (TPA), 874.1 g of ethylene glycol (EG), 1353.4 g of 1,4-cyclohexanedimethanol (CHDM), 12.8 g of Ge catalyst, 0.020 g of blue toner, and 0.010 g of red toner were added, and the esterification reaction was carried out at a pressure of 0.5 kgf / cm above atmospheric pressure. 2 The polycondensation reaction was carried out at a high pressure and temperature of 260°C, and the polycondensation reaction was carried out at a temperature of 280°C until the intrinsic viscosity (IV) became 0.70 dl / g, and then about 10 kg of polyester resin was obtained without carrying out solid-state polymerization.

[0232]

[0233] Comparative Example 2

[0234] The same procedure as in Example 1 was repeated, but 10037.5 g of regenerated bis(2-hydroxyethyl)terephthalate (r-BHET B2), 1640.0 g of terephthalic acid (TPA), 2143.8 g of ethylene glycol (EG), 2143.8 g of ethylene glycol (EG), 1067.0 g of 1,4-cyclohexanedimethanol (CHDM), 72.1 g of diethylene glycol (DEG), 0.4 g of Ti catalyst, 0.015 g of blue toner, and 0.005 g of red toner were added, and the esterification reaction was carried out at a pressure of 1 kgf / cm2 below atmospheric pressure. 2 The polycondensation reaction was carried out at a high pressure and a temperature of 265°C, and the polycondensation reaction was carried out at a temperature of 270°C until the intrinsic viscosity (IV) became 0.70 dl / g, and then the solid-state polymerization reaction was carried out at a temperature of 200°C until the intrinsic viscosity (IV) became 0.90 dl / g, thereby obtaining about 10 kg of polyester resin.

[0235]

[0236] The types and contents of regenerated BHET and the input amounts of monomers used in the above examples and comparative examples are summarized in the table below.

[0237] Item Information Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Regeneration BHET Type A1 A2 A3 A4 A5 A6 A7 Weight % 5 38 46 5 16 36 9 46 5 Monomer input (molar part) TPA 2 4.7 0.0 14.3 35.0 28.0 2.6 14.6 EG 9.9 0.0 2.9 0.1 28.9 3.6 1.6 DEG 0.7 1.3 33.00.00.03.4 CHDM 7.49.46.7 26.2 11.7 0.0 9.7 CHDM Derivative0.00.01.30.00.80.80.0ISB2.00.00.011.70.00.03.2r-BHET24.747.033.48.718.749.334.1

[0238] Item information Comparison example 1 Comparison example 2 Regenerated BHET type B1 B2 Weight % 4869 Monomer input (molar part) TPA 2 3.5 9.9 EG 14.1 34.6 DEG 0.00.7 CHDM 9.4 7.4 CHDM derivative 0.00.0 ISB 0.00.0 r-BHET 2 3.5 3 9.5

[0239]

[0240] Exam example

[0241]

[0242] (1) Heat resistance index

[0243] The heat resistance index was calculated as follows for the polyester resin obtained in the examples and comparisons.

[0244] a. Resin heat resistance index

[0245] The resin heat resistance index was calculated according to the equation (Ia) below.

[0246] Resin heat resistance index = ethylene glycol mole fraction x 0.02 (Ia)

[0247] Here, the ethylene glycol mole fraction is the content (mol%) of the ethylene glycol component based on the total mole number of diol components contained in the polyester resin.

[0248] b. Regeneration heat resistance index

[0249] The regenerative heat resistance index was calculated according to the equation (Ib) below.

[0250] Regeneration heat resistance index = (r-BHET TDI) x r-BHET weight fraction x 2 (Ib)

[0251] Here, the r-BHET weight fraction is the content (weight%) of recycled BHET based on the total weight of the polyester resin, and the r-BHET TDI used the TDI value of recycled BHET calculated in the previous test example.

[0252] c. Total heat resistance index

[0253] The total heat resistance index was calculated using the previously obtained resin heat resistance index and regenerated heat resistance index as in the following formula (I).

[0254] Total heat resistance index = resin heat resistance index + recycled heat resistance index (I)

[0255]

[0256] (2) △Col-b

[0257] Color changes in the polyester resin obtained in the examples and comparisons were measured in a high temperature and humidity environment.

[0258] a. Early Col-b

[0259] Reflection data was obtained from pellets of polyester resin at an observer angle of 2° using Hunterlab's Color Flex EZ with Illuminant D65, and the b value of the Hunter Lab color space was obtained using the color analysis device within the software.

[0260] b. Col-b after high temperature and humidity storage

[0261] After storing the polyester resin at 50℃ and 60%RH for 10 days, the b value of the Hunter Lab color space was obtained in the same manner as before.

[0262] c. △Col-b

[0263] △Col-b was calculated according to the formula below.

[0264] △Col-b = Col-b [10D] - Col-b [0D]

[0265] Here

[0266] Col-b [10D] is the b value of the Hunter Lab color space measured after storing the polyester resin at 50℃ and 60%RH for 10 days.

[0267] Col-b [0D] is the b value of the Hunter Lab color space measured for the polyester resin prior to storage.

[0268]

[0269] (3) LC-UV

[0270] The content of acetaldehyde (ppm) in the polyester resins obtained in the examples and comparisons was measured through LC-UV (Liquid chromatography with UV detector) analysis as follows. Specifically, the acetaldehyde content refers to the content of acetaldehyde based on the weight of the polyester resin (i.e., ppmw).

[0271] - A sample was prepared by adding 1 g of polyester resin to 10 mL of an acetonitrile / deionized water mixture (50 / 50 volume ratio), and 200 μL of acidified 2,3-dinitrophenylhydrazine (2,3-DNPH) was added thereto, followed by stirring at 37 degrees for 1 hour.

[0272] - Column: QUASAR C18 5 ㎛

[0273] - Column temperature: 35℃

[0274] - Sample volume: 20 μL

[0275] - Diluent: Acetonitrile / deionized water mixture

[0276] - Flow rate: 0.8 mL / min

[0277] - Detector: UV, 363 nm

[0278] - The quantification of acetaldehyde was calibrated using a standard range of 0.05 to 20 mg / L. The r of the calibration model 2 If it was greater than or equal to 0.995, it was considered valid.

[0279]

[0280] (4) Intrinsic viscosity

[0281] The polyester resins obtained in the examples were dissolved in orthochlorophenol (OCP) at 100°C at a concentration of 0.12%, and then the intrinsic viscosity (IV, dl / g) was measured using a Ubbelrod viscometer in a constant temperature bath at 35°C. As a result, it was confirmed that all the polyester resins obtained in the examples had intrinsic viscosities within the range of 0.5 dl / g to 1.2 dl / g at 35°C.

[0282]

[0283] The results of the above test examples are shown in the table below.

[0284] Item Information Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Heat Resistance Index Regeneration Heat Resistance Index 1.8 12.68 2.25 0.61 1.83 3.50 2.23 Resin Heat Resistance Index 1.64 1.40 1.47 0.40 1.44 1.96 1.50 Total Heat Resistance Index 3.45 4.08 3.72 1.01 3.27 5.46 3.73 △Col-b 50℃, 60%, 10 days 0.3-0.7 0.15-0.5 0.10.6-0.85 LC-UV Acetaldehyde (ppm) 0.68 0.84 0.38 0.22 0.13 0.12 0.7

[0285] Item information Comparison Example 1 Comparison Example 2 Heat resistance index Regeneration heat resistance index 8.939.51 Resin heat resistance index 2.102.46 Total heat resistance index 11.0311.97△Col-b50℃, 60%, 10 days-1.11.5LC-UV Acetaldehyde (ppm) 3.21.2

[0286]

[0287] As can be seen from the test results above, the polyester resins of Examples 1 to 7, while using a recycled monomer, had acetaldehyde contents controlled within a certain range and exhibited excellent heat resistance and color quality. In contrast, the polyester resins of Comparative Examples 1 and 2 had acetaldehyde contents outside the desired range and exhibited poor heat resistance and color quality.

Claims

1. Contains regenerated bis(2-hydroxyethyl) terephthalate (BHET) obtained by depolymerization of waste polyester, A polyester resin having an acetaldehyde content of 1 ppm or less.

2. In paragraph 1, The above polyester resin Polyester resin having △Col-b in the range of -1 to +1 according to the following formula: △Col-b = Col-b [10D] - Col-b [0D] Here Col-b [10D] is the b value of the Hunter Lab color space measured after storing the polyester resin at 50℃ and 60%RH for 10 days. Col-b [0D] is the b value of the Hunter Lab color space measured for the polyester resin prior to storage.

3. In paragraph 1, The above polyester resin Polyester resin having a resin heat resistance index of 2.0 or less, calculated by the following formula (Ia): Resin heat resistance index = ethylene glycol mole fraction x 0.02 (Ia) Here, the ethylene glycol mole fraction is the content (mol%) of ethylene glycol components based on the total mole number of diol components contained in the polyester resin. Calculate by taking only the numerical values ​​excluding the units of the above parameters.

4. In paragraph 3, The above polyester resin Polyester resin having a regenerative heat resistance index of 7.0 or less, calculated by the following formula (Ib): Regeneration heat resistance index = (r-BHET TDI) x r-BHET weight fraction x 2 (Ib) Here r-BHET weight fraction is the content of recycled BHET (weight %) based on the total weight of the polyester resin, r-BHET TDI is defined by the following formula when analyzing the above-mentioned regenerated BHET using high-performance liquid chromatography (HPLC). r-BHET TDI = [DEG-ester-1] + [DEG-ester-2] x 2 + exp^[HA-ester] Here, DEG-ester-1 is the peak area fraction (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate, DEG-ester-2 is the peak area fraction (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate, and HA-ester is the peak area fraction (%) of 2-hydroxyethyl(2-acetoxyethyl)terephthalate. Calculate by taking only the numerical values ​​of these parameters, excluding their units.

5. In paragraph 4, The above polyester resin Polyester resin having a total heat resistance index of 9.0 or less, calculated by the following formula (I): Total heat resistance index = resin heat resistance index + recycled heat resistance index (I) Here The resin heat resistance index is calculated by the above formula (Ia), The regenerative heat resistance index is calculated using the above formula (Ib).

6. In paragraph 1, The above-mentioned regenerated bis(2-hydroxyethyl)terephthalate is When analyzed by high-performance liquid chromatography (HPLC), The peak area fraction of bis(2-hydroxyethyl)terephthalate is 95% or more, A polyester resin having a peak area fraction of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl] terephthalate of 2.5% or less.

7. In paragraph 1, The above-mentioned recycled bis(2-hydroxyethyl)terephthalate is a polyester resin having a thermal property drop index (TDI) of 3.0 or less, as defined by the following equation, when analyzed by high-performance liquid chromatography (HPLC): TDI = [DEG-ester-1] + [DEG-ester-2] x 2 + exp^[HA-ester] Here, DEG-ester-1 is the peak area fraction (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate, DEG-ester-2 is the peak area fraction (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate, and HA-ester is the peak area fraction (%) of 2-hydroxyethyl(2-acetoxyethyl)terephthalate, and the calculation is performed by taking only the numerical values ​​excluding the units of these parameters.

8. In paragraph 1, The above-mentioned regenerated bis(2-hydroxyethyl)terephthalate is When analyzed by high-performance liquid chromatography (HPLC), The peak area fraction of the acetate ester compound is 1.0% or less, A polyester resin having a peak area fraction of diethylene glycol ester compounds of 2.0% or less in total.

9. In paragraph 8, The above acetate ester compound includes 2-hydroxyethyl (2-acetoxyethyl) terephthalate, The above diethylene glycol ester compound is a polyester resin comprising 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate and bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate.

10. In paragraph 1, The above polyester resin comprises at least one comonomer selected from dicarboxylic acid and diol as a constituent component, The above dicarboxylic acid is at least one selected from the group consisting of isophthalic acid, dimethyl isophthalate, phthalic acid, dimethyl phthalate, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate, diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, maleic anhydride, fumaric acid, adipic acid, glutaric acid, and azelaic acid; The above diols are isosorbide, neopentylglycol 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate, and A polyester resin comprising at least one selected from the group consisting of 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol.

11. In paragraph 1, The above polyester resin A polyester resin comprising at least one recycled monomer selected from the group consisting of recycled ethylene glycol, recycled 1,4-cyclohexanedimethanol, recycled diethylene glycol, recycled neopentyl glycol, recycled isosorbide, recycled terephthalic acid, recycled dimethyl terephthalate, recycled isophthalic acid, and recycled dimethyl isophthalate.

12. In paragraph 1, The above polyester resin A polyester resin having an intrinsic viscosity of 0.5 dl / g to 1.2 dl / g at 35°C.

13. An article comprising a polyester resin according to paragraph 1.

14. In paragraph 13, The above article is a container, blown article, film, sheet, or profile.

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