TW202204500A - Method for manufacturing high-purity bis-(2-hydroxyethyl) terephthalate, recycled polyethylene terephthalate, decolorizing solvent and method for purifying bis-(2-hydroxyethyl) terephthalate - Google Patents

Method for manufacturing high-purity bis-(2-hydroxyethyl) terephthalate, recycled polyethylene terephthalate, decolorizing solvent and method for purifying bis-(2-hydroxyethyl) terephthalate Download PDF

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TW202204500A
TW202204500A TW110122376A TW110122376A TW202204500A TW 202204500 A TW202204500 A TW 202204500A TW 110122376 A TW110122376 A TW 110122376A TW 110122376 A TW110122376 A TW 110122376A TW 202204500 A TW202204500 A TW 202204500A
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hydroxyethyl
terephthalate
bis
purity
bhet
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高尾正樹
堺通
藤田博
稻田修司
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日商新科技股份有限公司
日商日本環境設計股份有限公司
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/48—Separation; Purification; Stabilisation; Use of additives
    • C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/48—Separation; Purification; Stabilisation; Use of additives
    • C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
    • C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
    • C07C69/76—Esters of carboxylic acids having a carboxyl group bound to a carbon atom of a six-membered aromatic ring
    • C07C69/80—Phthalic acid esters
    • C07C69/82—Terephthalic acid esters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
    • C08G63/16—Dicarboxylic acids and dihydroxy compounds
    • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
    • C08G63/181—Acids containing aromatic rings
    • C08G63/183—Terephthalic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C08J11/04—Recovery or working-up of waste materials of polymers
    • C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
    • C08J11/08—Recovery or working-up of waste materials of polymers without chemical reactions using selective solvents for polymer components
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C08J11/04—Recovery or working-up of waste materials of polymers
    • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C08J11/04—Recovery or working-up of waste materials of polymers
    • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
    • C08J11/16—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with inorganic material

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)

Abstract

To provide a method for easily manufacturing high-purity bis-(2-hydroxyethyl) terephthalate(BHET) from colored polyester waste. The method for manufacturing high-purity BHET according to the present invention includes: a depolymerization step of depolymerizing colored polyester waste to obtain a depolymerized product containing colored crude BHET; a concentration step of removing low boiling point components contained in the depolymerized product to concentrate BHET; a collection step of collecting BHET from the crude BHET to obtain medium-purity BHET; a crystallization-separation step of crystallizing the medium-purity BHET in a decolorizing solvent and separating crystals from a solvent component containing a colorant to thereby obtain purified BHET; and a solvent removal step of removing solvent remaining in the crystals of the purified BHET to obtain high-purity BHET.

Description

高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法、再生聚對苯二甲酸乙二酯、脫色溶劑及雙-(2-羥乙基)對苯二甲酸酯的精製方法Production method of high-purity bis-(2-hydroxyethyl) terephthalate, recycled polyethylene terephthalate, decolorizing solvent and bis-(2-hydroxyethyl) terephthalate Refinement method

本發明係有關一種自被著色的聚酯(polyester)廢棄物(特別是被著色的聚酯衣料廢棄物)製造高純度雙-(2-羥乙基)對苯二甲酸酯的方法，以及使用了此高純度雙-(2-羥乙基)對苯二甲酸酯的再生聚對苯二甲酸乙二酯。 另外，本發明係有關一種用於自被著色的雙-(2-羥乙基)對苯二甲酸酯簡便地去除色素以進行脫色之脫色溶劑，以及使用了此脫色溶劑之雙-(2-羥乙基)對苯二甲酸酯的精製方法。The present invention relates to a method for producing high-purity bis-(2-hydroxyethyl) terephthalate from dyed polyester waste (particularly dyed polyester clothing waste), and Recycled polyethylene terephthalate using this high purity bis-(2-hydroxyethyl) terephthalate. In addition, the present invention relates to a decolorizing solvent for decolorizing by simply removing pigment from colored bis-(2-hydroxyethyl) terephthalate, and bis-(2-(2-hydroxyethyl)) using the decolorizing solvent. - Process for the purification of hydroxyethyl) terephthalate.

聚酯(例如聚對苯二甲酸乙二酯(polyethylene terephthalate；PET))係因其優異的特性而被廣泛使用作為衣物、薄膜、樹脂成型品等。然而，對於在該等產品的製造步驟中產生的像是線纖維、膜片、樹脂片等之聚酯屑(製造步驟中的損失)，以及像是使用完的寶特瓶(plastic bottle)之使用完的成型品之廢棄物的有效利用，不僅是在成本面，就連在環境面也成為很大的課題。物料再循環(material recycling)、熱再循環(thermal recycling)、化學再循環(chemical recycling)等被檢視及提案來作為該等的處理方法。Polyester (eg, polyethylene terephthalate (PET)) is widely used as clothing, films, resin molded articles, and the like because of its excellent properties. However, for polyester crumbs such as thread fibers, film sheets, resin sheets, etc. generated during the manufacturing steps of these products (loss during manufacturing steps), and products such as used plastic bottles Effective utilization of the waste of used molded products has become a major issue not only in terms of cost but also in terms of environment. Material recycling, thermal recycling, chemical recycling, etc. are reviewed and proposed as such treatment methods.

其中，在物料再循環中，有關像是使用完的寶特瓶等之聚酯成型品的廢棄物，主要是由地方政府回收並積極地進行再利用。另外，有關線纖維屑係利用將纖維屑加工成所謂爆米花(popcorn)的大顆粒之錠粒狀物之後，進行再熔融以再生成線纖維等的手法來實行物料再循環。然而，關於衣物，係極難以適用物料再循環方法，故未有任何再利用的實例。Among them, in material recycling, wastes related to polyester molded products such as used PET bottles are mainly collected by local governments and actively reused. In addition, regarding the thread flakes, after processing the flakes into large granular ingots called popcorn, and then remelting them to regenerate thread fibers, etc., material recycling is implemented. However, with regard to clothes, it is extremely difficult to apply the material recycling method, so there is no example of reuse.

又於熱再循環中，係將包含衣物、線纖維屑的聚酯廢棄物轉換成(conversion)燃料，因而具有可再利用聚酯廢棄物之燃燒熱的優點。然而，由於聚酯的放熱值(heat release value)相對較低，若要利用燃燒熱則不得不燃燒大量的聚酯廢棄物。為此，具有聚酯原料的損失及二氧化碳產生的問題，因而在節省資源及環境保護的面向上來看是不利的。In thermal recycling, polyester wastes including clothing and lint are converted into fuels, so the heat of combustion of polyester wastes can be reused. However, due to the relatively low heat release value of polyester, a large amount of polyester waste has to be burned if the heat of combustion is to be utilized. For this reason, there are problems of loss of polyester raw materials and generation of carbon dioxide, which is disadvantageous in terms of resource saving and environmental protection.

相對於此，於化學再循環中，係將聚酯廢棄物再生成原料單體(raw material monomer)之雙-(2-羥乙基)對苯二甲酸酯(bis-(2-hydroxyethyl)terephthalate)(以下亦稱為「BHET」)，或是對苯二甲酸二甲酯(dimethyl terephthalate)(以下亦稱為「DMT」)，並使該經再生的BHET或DMT再次進行聚縮合反應(polycondensation reaction)，以製造新的聚酯(參照例如發明專利文獻1至3)。由此，伴隨著再生所引起的聚酯之品質降低的情況少，故作為封閉式再生循環(closed loop recycling)很優秀。然而，即使是在化學再循環中，大部分也是以無著色且雜質少的使用完之寶特瓶、樹脂屑、膜屑等作為再循環的對象。On the other hand, in chemical recycling, polyester waste is regenerated into bis-(2-hydroxyethyl) terephthalate (bis-(2-hydroxyethyl) as raw material monomer). terephthalate) (hereinafter also referred to as "BHET"), or dimethyl terephthalate (dimethyl terephthalate) (hereinafter also referred to as "DMT"), and make the regenerated BHET or DMT undergo a polycondensation reaction again ( polycondensation reaction) to produce new polyesters (see, for example, Invention Patent Documents 1 to 3). As a result, the quality of the polyester is less likely to be deteriorated due to the regeneration, so it is excellent as a closed loop recycling. However, even in chemical recycling, most of the used bottles, resin chips, film chips, etc. that are non-colored and have few impurities are recycled.

在將被著色的聚酯衣料廢棄物作為再循環原料的情況下，為了從聚酯衣料廢棄物歷經原料單體而再次使聚酯再生，將染料、顏料等的著色用色素去除是必要條件。已知當經再生的原料單體中具有大量的著色用色素混入時，則經再生的聚酯亦會有著色(特別是黃化)的情形。 此外，聚酯衣料廢棄物中係含有以滿足因應了衣料用途所需特性為目的而使用的穩定劑、抗靜電劑、易染劑、阻燃劑、吸濕劑、氣體阻隔劑等各種化合物；部分被使用在衣料上的尼龍(nylon)、聚氨酯(urethane)、棉(cotton)、烯烴(olefin)等不同的材料；被用作為消光劑之氧化鈦等的添加劑，以及拉鍊、紐扣、金屬、玻璃、沙子等雜質。因此，為了再生聚酯衣料廢棄物，有效地去除上述物質也很重要。In the case of using colored polyester clothing waste as a recycling raw material, it is necessary to remove coloring dyes such as dyes and pigments in order to regenerate polyester through raw material monomers from the polyester clothing waste. It is known that when a large amount of coloring pigments are mixed in the regenerated raw material monomer, the regenerated polyester will also be colored (especially yellowed). In addition, polyester clothing waste contains various compounds such as stabilizers, antistatic agents, dyeing agents, flame retardants, hygroscopic agents, gas barrier agents, etc., which are used for the purpose of satisfying the properties required for the application of clothing; Different materials such as nylon, urethane, cotton, and olefin are partly used in clothing; additives such as titanium oxide are used as matting agents, as well as zippers, buttons, metal, Glass, sand and other impurities. Therefore, in order to recycle polyester clothing waste, it is also important to remove the above-mentioned substances efficiently.

例如參照發明專利文獻4及發明專利文獻5，其等提出在自被著色的纖維狀聚酯去除染料、顏料等的著色劑後，歷經原料單體之DMT至再次獲得再生聚酯的化學再循環方法。 然而，記載於發明專利文獻4及發明專利文獻5中的方法係從被著色的纖維狀聚酯回收DMT的方法，由於再循環步驟長，需要大量的能源，故在成本上面臨很多課題。又， 經精製的再循環DMT很大的缺點係在於無法直接使用於以目前在世界上普遍使用的對苯二甲酸(terephthalic acid)作為原料之聚合製程(對苯二甲酸製程)。〔先前技術文獻〕 〔發明專利文獻〕 For example, refer to Invention Patent Document 4 and Invention Patent Document 5, which propose a chemical recycling process in which colorants such as dyes, pigments, etc. are removed from the colored fibrous polyester, and after DMT of the raw material monomers to obtain regenerated polyester again method. However, the methods described in Invention Patent Document 4 and Invention Patent Document 5 are methods for recovering DMT from colored fibrous polyesters, and since the recycling steps are long and require a large amount of energy, there are many problems in terms of cost. In addition, the major disadvantage of the purified recycled DMT is that it cannot be directly used in a polymerization process (terephthalic acid process) using terephthalic acid, which is currently widely used in the world, as a raw material. [Prior Art Documents] [Invention Patent Documents]

〔發明專利文獻1〕日本特許第3715812號公報。 〔發明專利文獻2〕日本特許第5189266號公報。 〔發明專利文獻3〕日本特許第4067306號公報。 〔發明專利文獻4〕日本特許第4537288號公報。 〔發明專利文獻5〕日本特許第5134563號公報。[Invention Patent Document 1] Japanese Patent No. 3715812. [Invention Patent Document 2] Japanese Patent No. 5189266. [Invention Patent Document 3] Japanese Patent No. 4067306 . [Invention Patent Document 4] Japanese Patent No. 4537288. [Invention Patent Document 5] Japanese Patent No. 5134563.

〔發明所欲解決之課題〕[The problem to be solved by the invention]

本發明的目的係在於提供一種自被著色的聚酯廢棄物(特別是聚酯衣料廢棄物)高效地去除染料、顏料等的色素而得以簡便地製造高純度的雙-(2-羥乙基)對苯二甲酸酯之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，以及將此高純度雙-(2-羥乙基)對苯二甲酸酯作為原料所製造的再生聚對苯二甲酸乙二酯。 另外，本發明還提供一種用於自被著色的雙-(2-羥乙基)對苯二甲酸酯順利地去除色素以進行脫色之脫色溶劑，以及使用了此脫色溶劑之雙-(2-羥乙基)對苯二甲酸酯的精製方法。〔解決課題之技術手段〕 An object of the present invention is to provide a high-purity bis-(2-hydroxyethyl) that can be easily produced by efficiently removing dyes such as dyes and pigments from colored polyester waste (particularly, polyester clothing waste). ) The production method of high-purity bis-(2-hydroxyethyl) terephthalate of terephthalate, and this high-purity bis-(2-hydroxyethyl) terephthalate as Recycled polyethylene terephthalate produced from raw materials. In addition, the present invention also provides a decolorizing solvent for smoothly removing pigment from colored bis-(2-hydroxyethyl) terephthalate for decolorization, and bis-(2-(2) using the decolorizing solvent) - Process for the purification of hydroxyethyl) terephthalate. [Technical means for solving problems]

上述的目的係可藉由下列(1)至(16)之本發明來達成。 (1) 一種高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其具備： 解聚步驟，係混合藉由色素而被著色之聚酯廢棄物與單乙二醇及解聚觸媒，而將前述聚酯廢棄物進行解聚以獲得含有被著色之粗製雙-(2-羥乙基)對苯二甲酸酯的解聚物的步驟； 濃縮步驟，係自前述解聚物去除含有前述單乙二醇的低沸點成分，而濃縮前述粗製雙-(2-羥乙基)對苯二甲酸酯的步驟； 回收步驟，係自經濃縮之前述粗製雙-(2-羥乙基)對苯二甲酸酯回收前述雙-(2-羥乙基)對苯二甲酸酯，以獲得純度高於前述粗製雙-(2-羥乙基)對苯二甲酸酯之中純度雙-(2-羥乙基)對苯二甲酸酯的步驟； 晶析分離步驟，係藉由將前述中純度雙-(2-羥乙基)對苯二甲酸酯溶解於脫色溶劑之溶解液進行冷卻，而使前述雙-(2-羥乙基)對苯二甲酸酯的結晶析出，並將前述結晶與含有前述色素之溶劑成分進行固液分離，以獲得純度高於前述中純度雙-(2-羥乙基)對苯二甲酸酯之精製雙-(2-羥乙基)對苯二甲酸酯的步驟；以及 脫溶劑步驟，係去除殘留在前述結晶中之前述溶劑成分，以獲得純度高於前述精製雙-(2-羥乙基)對苯二甲酸酯之高純度雙-(2-羥乙基)對苯二甲酸酯的步驟。The above-mentioned objects can be achieved by the present invention of the following (1) to (16). (1) a kind of manufacture method of high-purity bis-(2-hydroxyethyl) terephthalate, it has: The depolymerization step is to mix the polyester waste colored by the pigment with monoethylene glycol and a depolymerization catalyst, and depolymerize the polyester waste to obtain the colored crude bis-(2- a step of depolymerization of hydroxyethyl) terephthalate; The concentration step is a step of removing the low-boiling component containing the monoethylene glycol from the depolymerization, and concentrating the crude bis-(2-hydroxyethyl) terephthalate; The recovery step is to recover the aforementioned bis-(2-hydroxyethyl) terephthalate from the concentrated aforementioned crude bis-(2-hydroxyethyl) terephthalate, so as to obtain a higher purity than the aforementioned crude bis-(2-hydroxyethyl) terephthalate The step of pure bis-(2-hydroxyethyl) terephthalate in bis-(2-hydroxyethyl) terephthalate; The crystallization separation step is to cool the solution obtained by dissolving the medium-purity bis-(2-hydroxyethyl) terephthalate in a decolorizing solvent, so that the bis-(2-hydroxyethyl) bis-(2-hydroxyethyl) The crystallization of phthalic acid ester is precipitated, and the solid-liquid separation of the above-mentioned crystal and the solvent component containing the above-mentioned pigment is carried out to obtain the purification of bis-(2-hydroxyethyl) terephthalate with a purity higher than the above-mentioned medium purity the step of bis-(2-hydroxyethyl)terephthalate; and The desolvation step is to remove the aforementioned solvent components remaining in the aforementioned crystals to obtain high-purity bis-(2-hydroxyethyl) with a purity higher than the aforementioned purified bis-(2-hydroxyethyl) terephthalate Steps for terephthalates.

(2) 如上述(1)所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述晶析分離步驟使用的前述脫色溶劑係含有選自由碳原子數為4至12之乙二醇單醚或乙二醇二醚，以及碳原子數為2至6之乙二醇所構成的群組之至少一種的乙二醇類化合物。 (3) 如上述(2)所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述晶析分離步驟使用的前述脫色溶劑中之前述乙二醇類化合物的含量係85質量%以上。(2) The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to (1) above, wherein the decolorizing solvent used in the crystallization and separation step contains carbon atoms selected from the group consisting of carbon atoms. At least one ethylene glycol compound selected from the group consisting of ethylene glycol monoether or ethylene glycol diether with 4 to 12 carbon atoms and ethylene glycol with 2 to 6 carbon atoms. (3) The method for producing high-purity bis-(2-hydroxyethyl)terephthalate as described in (2) above, wherein the ethylene glycol in the decolorizing solvent used in the crystallization separation step The content of the quasi-compound is 85% by mass or more.

(4) 如上述(1)至(3)中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中前述色素係具有包含氮原子之發色基，且殘留在前述高純度雙-(2-羥乙基)對苯二甲酸酯中之前述氮原子的含量係20 ppm以下。 (5) 如上述(1)至(4)中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中前述聚酯廢棄物係包括65質量%以上之聚對苯二甲酸乙二酯。 (6) 如上述(1)至(5)中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中前述聚酯廢棄物係聚酯衣料廢棄物。(4) The method for producing high-purity bis-(2-hydroxyethyl)terephthalate according to any one of (1) to (3) above, wherein the coloring matter has a nitrogen atom-containing Chromophore, and the content of the nitrogen atom remaining in the high-purity bis-(2-hydroxyethyl) terephthalate is 20 ppm or less. (5) The method for producing high-purity bis-(2-hydroxyethyl) terephthalate as described in any one of (1) to (4) above, wherein the polyester waste is composed of 65 Mass % or more of polyethylene terephthalate. (6) The method for producing high-purity bis-(2-hydroxyethyl)terephthalate according to any one of (1) to (5) above, wherein the polyester waste is polyester Clothing waste.

(7) 如上述(6)所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述解聚步驟中係將前述聚酯衣料廢棄物在衣料的形態下進行解聚。 (8) 如上述(6)或(7)所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述解聚步驟後係進一步具備固形物去除步驟，前述固形物去除步驟係自前述解聚物去除前述聚酯衣料廢棄物中所含之不溶於聚酯的固體成分。 (9) 如上述(1)至(8)中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述解聚步驟後係進一步具備色素預去除步驟，前述色素預去除步驟係自前述解聚物去除一部分的前述色素。(7) The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to (6) above, wherein in the depolymerization step, the polyester clothing waste is placed in a clothing material. disaggregated in the form. (8) The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to (6) or (7) above, further comprising a solid matter removal step after the depolymerization step , the solids removal step is to remove the polyester-insoluble solids contained in the polyester clothing waste from the depolymerization. (9) The method for producing high-purity bis-(2-hydroxyethyl)terephthalate according to any one of (1) to (8) above, wherein after the depolymerization step, a further A pigment pre-removal step is provided, and the pigment pre-removal step is to remove a part of the pigment from the depolymerization.

(10) 如上述(9)所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中前述色素係具有含有氮原子之發色基，且前述色素預去除步驟係進行到殘留在前述解聚物中的前述氮原子的含量成為900 ppm以下為止。 (11) 一種再生聚對苯二甲酸乙二酯，係藉由如上述(1)至(10)中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法而得之高純度雙-(2-羥乙基)對苯二甲酸酯的聚縮合物。 (12) 如上述(11)所記載之再生聚對苯二甲酸乙二酯，其中前述再生聚對苯二甲酸乙二酯係含有50質量%以上之源自前述高純度雙-(2-羥乙基)對苯二甲酸酯的結構。(10) The method for producing high-purity bis-(2-hydroxyethyl) terephthalate as described in (9) above, wherein the colorant has a chromophore group containing a nitrogen atom, and the colorant is preliminarily removed The step is performed until the content of the nitrogen atoms remaining in the depolymerization becomes 900 ppm or less. (11) A regenerated polyethylene terephthalate obtained by using the high-purity bis-(2-hydroxyethyl) terephthalic acid as described in any one of (1) to (10) above A polycondensate of high-purity bis-(2-hydroxyethyl) terephthalate obtained by the method for producing an ester. (12) The regenerated polyethylene terephthalate according to the above (11), wherein the regenerated polyethylene terephthalate contains 50 mass % or more of the high-purity bis-(2-hydroxyl ethyl) terephthalate structure.

(13) 一種脫色溶劑，係用於自藉由色素而被著色之雙-(2-羥乙基)對苯二甲酸去除前述色素以進行脫色的脫色溶劑，其含有選自由碳原子數為4至12之乙二醇單醚或乙二醇二醚，以及碳原子數為2至6之乙二醇所構成的群組之至少一種的乙二醇類化合物。 (14) 如上述(13)所記載之脫色溶劑，其中前述脫色溶劑中之前述乙二醇類化合物的含量係85質量%以上。(13) A decolorizing solvent used for removing the aforementioned pigment from bis-(2-hydroxyethyl) terephthalic acid colored by a pigment to decolorize, comprising a solvent selected from the group consisting of 4 carbon atoms Ethylene glycol monoether or ethylene glycol diether from 12 to 12, and at least one ethylene glycol compound of the group consisting of ethylene glycol with 2 to 6 carbon atoms. (14) The decolorizing solvent according to (13) above, wherein the content of the glycol-based compound in the decolorizing solvent is 85% by mass or more.

(15) 一種雙-(2-羥乙基)對苯二甲酸酯的精製方法，係透過將藉由色素而被著色之雙-(2-羥乙基)對苯二甲酸酯溶解於脫色溶劑之溶解液進行冷卻，而使前述雙-(2-羥乙基)對苯二甲酸酯的結晶析出，並將前述結晶與含有前述色素之溶劑成分進行固液分離，以精製前述雙-(2-羥乙基)對苯二甲酸酯的方法； 前述脫色溶劑係含有選自由碳原子數為4至12之乙二醇單醚或乙二醇二醚，以及碳原子數為2至6之乙二醇所構成的群組之至少一種的乙二醇類化合物。 (16) 如上述(15)所記載之雙-(2-羥乙基)對苯二甲酸酯的精製方法，其中前述脫色溶劑中之前述乙二醇類化合物的含量係85質量%以上。〔發明之功效〕 (15) A method for purifying bis-(2-hydroxyethyl) terephthalate, comprising dissolving bis-(2-hydroxyethyl) terephthalate colored by a pigment in a The dissolving solution of the decolorizing solvent is cooled, so that the crystals of the aforementioned bis-(2-hydroxyethyl) terephthalate are precipitated, and the aforementioned crystals and the solvent components containing the aforementioned pigments are subjected to solid-liquid separation to purify the aforementioned bis-(2-hydroxyethyl) terephthalate. -The method of (2-hydroxyethyl) terephthalate; The aforesaid decolorizing solvent contains ethylene glycol monoether or ethylene glycol diether selected from the group consisting of 4 to 12 carbon atoms, and 2 carbon atoms At least one ethylene glycol compound selected from the group consisting of ethylene glycol to 6. (16) The method for purifying bis-(2-hydroxyethyl)terephthalate according to (15) above, wherein the content of the glycol-based compound in the decolorizing solvent is 85% by mass or more. [Effect of invention]

根據本發明，能夠高效地自被著色的聚酯廢棄物(特別是聚酯衣料廢棄物)去除染料、顏料等的色素以簡便地製造高純度的雙-(2-羥乙基)對苯二甲酸酯(BHET)。特別是由於可自被著色的聚酯衣料廢棄物簡便地製造高純度的BHET，故能夠將至今為止大多以焚燒處理、掩埋處理等來進行處理的聚酯衣料廢棄物歷經原料單體而再次使聚酯再生。其結果能夠實現使聚酯衣料廢棄物成為再生聚酯之封閉式再生循環，且能夠為循環再生型社會的建立做出很大的貢獻。 另外，透過本發明所精製的再生BHET能夠直接使用於以目前在世界上普遍使用的對苯二甲酸作為原料之聚合製程(對苯二甲酸製程)，故具有很大的優勢。According to the present invention, dyes such as dyes and pigments can be efficiently removed from colored polyester waste (particularly polyester clothing waste) to easily produce high-purity bis-(2-hydroxyethyl)terephthalene. Formate (BHET). In particular, since high-purity BHET can be easily produced from dyed polyester clothing waste, it is possible to recycle polyester clothing waste, which has been generally treated by incineration, landfill, etc., through raw material monomers. Recycled polyester. As a result, a closed recycling cycle can be realized in which polyester clothing waste is recycled polyester, and a great contribution can be made to the establishment of a recycling-oriented society. In addition, the regenerated BHET purified by the present invention can be directly used in the polymerization process (terephthalic acid process) using terephthalic acid, which is commonly used in the world, as a raw material, so it has great advantages.

以下將根據圖式之較佳的實施態樣，針對本發明之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法、再生聚對苯二甲酸乙二酯、脫色溶劑及雙-(2-羥乙基)對苯二甲酸酯的精製方法進行詳細地說明。 此外，以下的說明係用以例示本發明者，並非用以限制本發明的範圍者。只要符合本發明之主旨，其他的實施態樣亦當然得屬於本發明的範疇。 例如在本發明中的「步驟」係並非僅意指能夠與其他步驟區隔識別之步驟者，亦指與其他操作組合之步驟者、實際上被分散成複數個步驟者、在此「步驟」中包括其他的步驟要件者、以及可在一個步驟中合併實施複數個步驟的操作者，只要符合發明之主旨皆得屬於本發明的範疇。Hereinafter, according to the preferred embodiments of the drawings, the method for producing high-purity bis-(2-hydroxyethyl) terephthalate, the regenerated polyethylene terephthalate, and the decolorizing solvent of the present invention will be described below. And the purification method of bis-(2-hydroxyethyl) terephthalate is demonstrated in detail. In addition, the following description is for illustrating the present invention, not for limiting the scope of the present invention. As long as it conforms to the gist of the present invention, other embodiments also belong to the scope of the present invention. For example, the "step" in the present invention does not only refer to a step that can be distinguished and identified from other steps, but also refers to a step that is combined with other operations, and is actually dispersed into a plurality of steps, here "step" Those that include other step requirements, and those who can perform a plurality of steps in one step, all belong to the scope of the present invention as long as the gist of the invention is met.

圖1係顯示本發明之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法之較佳實施態樣的流程圖。 本發明之高純度雙-(2-羥乙基)對苯二甲酸酯(bis-(2-hydroxyethyl) terephthalate；BHET)的製造方法係可適用於衣物、膜、樹脂成型品(例如寶特瓶)等各種被著色之聚酯廢棄物(以下亦記載為「著色聚酯廢棄物」)。此外，在以下的說明中，對於著色聚酯廢棄物係針對適用於被著色之聚酯製的衣料廢棄物(著色聚酯衣料廢棄物)之情形進行說明。FIG. 1 is a flow chart showing a preferred embodiment of the method for producing high-purity bis-(2-hydroxyethyl) terephthalate of the present invention. The method for producing high-purity bis-(2-hydroxyethyl) terephthalate (BHET) of the present invention can be applied to clothing, films, and resin-molded articles (such as PET Bottles) and other colored polyester waste (hereinafter also referred to as "colored polyester waste"). In addition, in the following description, the case where the colored polyester waste is applied to the colored polyester clothing waste (colored polyester clothing waste) will be described.

本實施態樣之高純度BHET的製造方法係具備(1)解聚步驟、(2)固形物去除步驟、(3)色素預去除步驟、(4)濃縮步驟、(5)回收步驟、(6)晶析分離步驟以及(7)脫溶劑步驟。 以下係依序說明各步驟。The method for producing high-purity BHET according to the present embodiment includes (1) a depolymerization step, (2) a solid matter removal step, (3) a pigment pre-removal step, (4) a concentration step, (5) a recovery step, and (6) a ) crystallization separation step and (7) desolvation step. The steps are described in sequence below.

(1) 解聚步驟 首先，將藉由染料、顏料等的色素(著色用色素)而被著色之聚酯衣料廢棄物與單乙二醇(monoethylene glycol)(以下亦記載為「MEG」)以及解聚觸媒加入反應槽中混合，將著色聚酯衣料廢棄物進行解聚以獲得含有經著色之粗製BHET的解聚液(液狀的解聚物)。以下，亦將含有經著色之粗製BHET的解聚液記載為「著色解聚液」。 作為構成聚酯衣料之聚酯係可列舉例如聚對苯二甲酸乙二酯(polyethylene terephthalate；PET)、聚對苯二甲酸丙二酯(polytrimethylene terephthalate；PTT)、聚對苯二甲酸丁二酯(polybutylene terephthalate；PBT)、聚萘二甲酸乙二酯(polyethylene naphthalate；PEN)、聚萘二甲酸丁二酯(polybutylene naphthalate；PBN)等。(1) Depolymerization step First, polyester clothing wastes colored by dyes such as dyes and pigments (coloring dyes) are reacted with monoethylene glycol (hereinafter also referred to as "MEG") and a depolymerization catalyst. Mixed in a tank, the colored polyester clothing waste was depolymerized to obtain a depolymerized liquid (liquid depolymerized) containing the colored crude BHET. Hereinafter, the depolymerization liquid containing the colored crude BHET is also described as "colored depolymerization liquid". Examples of polyester systems constituting polyester clothing include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), and polybutylene terephthalate. (polybutylene terephthalate; PBT), polyethylene naphthalate (polyethylene naphthalate; PEN), polybutylene naphthalate (polybutylene naphthalate; PBN) and the like.

於本發明中作為對象的聚酯衣料較佳地係主要由聚對苯二甲酸乙二酯(PET)纖維所構成的衣料。 此類聚酯衣料係可包含尼龍、聚氨酯、棉、烯烴等不同的材料；亦可包含以滿足因應了衣料用途所需特性為目的而使用的穩定劑、抗靜電劑、易染劑、阻燃劑、吸濕劑、氣體阻隔劑等各種化合物；被用作為消光劑之氧化鈦等的添加劑，以及拉鍊、紐扣、金屬、玻璃、沙子等的固形物。The polyester clothing targeted for the present invention is preferably a clothing mainly composed of polyethylene terephthalate (PET) fibers. This type of polyester clothing can contain different materials such as nylon, polyurethane, cotton, olefin, etc.; it can also contain stabilizers, antistatic agents, dye-promoting agents, flame retardants used for the purpose of satisfying the characteristics required by the application of the clothing. Various compounds such as agents, hygroscopic agents, gas barrier agents, etc.; additives such as titanium oxide used as matting agents, and solids such as zippers, buttons, metal, glass, sand, etc.

在聚酯衣料中所包含的PET(例如PET纖維)之含量雖然未特別予以限定，但較佳地係65質量%以上、更佳地係75質量%以上、再更佳地係85質量%以上、特佳地係95質量%以上。此外，其上限值為100質量%。The content of PET (for example, PET fiber) contained in the polyester clothing is not particularly limited, but is preferably 65% by mass or more, more preferably 75% by mass or more, still more preferably 85% by mass or more , The best land is more than 95% by mass. In addition, its upper limit is 100 mass %.

用在聚酯衣料的著色(染色)之色素大致分為染料及顏料。 作為染料，雖然可列舉例如分散染料(disperse dye)、萘酚染料(naphthol dye)、媒染染料(mordant dye)、甕染料(vat dye)等，但較佳地係分散染料。由於此分散染料係藉由聚酯與凡得瓦力(van der Waals force)而鍵結(bonding)，因此最適合聚酯的著色。再者，根據本發明人等之檢視，得知若將本發明用來去除分散染料，則具有良好的功效。Pigments used for coloring (dyeing) of polyester clothing are roughly classified into dyes and pigments. Examples of dyes include disperse dyes, naphthol dyes, mordant dyes, vat dyes, and the like, but are preferably disperse dyes. Since this disperse dye is bonded by polyester and van der Waals force, it is most suitable for polyester coloring. Furthermore, according to the inspection of the present inventors, it was found that if the present invention is used to remove disperse dyes, it has a good effect.

作為此類分散染料係可列舉例如被分類於C.I. Disperse Black(比色指數(Color Index)分散黑)之化合物、被分類於C.I. Disperse Blue(藍)之化合物、被分類於C.I. Disperse Red(紅)之化合物、被分類於C.I. Disperse Orange(橙)之化合物、被分類於C.I. Disperse Yellow(黃)之化合物、被分類於C.I. Disperse Green(綠)之化合物、被分類於C.I. Disperse Violet(紫)之化合物、被分類於C.I. Disperse Brown(棕)之化合物等。Examples of such disperse dyes include compounds classified in CI Disperse Black (Color Index), compounds classified in CI Disperse Blue (blue), and compounds classified in CI Disperse Red (red). Compounds classified as CI Disperse Orange (Orange), Compounds classified as CI Disperse Yellow (Yellow), Compounds classified as CI Disperse Green (Green), Compounds classified as CI Disperse Violet (Purple) , Compounds classified in CI Disperse Brown (brown), etc.

另一方面，作為顏料係可列舉例如被分類於C.I. Pigment Black(比色指數色素黑)之化合物、被分類於C.I. Pigment Blue(藍)之化合物、被分類於C.I. Pigment Red(紅)之化合物、被分類於C.I. Pigment Orange(橙)之化合物、被分類於C.I. Pigment Yellow(黃)之化合物、被分類於C.I. Pigment Green(綠)之化合物、被分類於C.I. Pigment Violet(紫)之化合物、被分類於C.I. Pigment Brown(棕)之化合物等。On the other hand, examples of the pigment system include compounds classified in CI Pigment Black (color index pigment black), compounds classified in CI Pigment Blue (blue), compounds classified in CI Pigment Red (red), Compounds classified in CI Pigment Orange (orange), compounds classified in CI Pigment Yellow (yellow), compounds classified in CI Pigment Green (green), compounds classified in CI Pigment Violet (purple), classified Compounds in CI Pigment Brown (brown), etc.

雖然被供給用於解聚之聚酯衣料廢棄物的形態係可為未經裁剪而呈衣料的形態，亦可為經裁剪之呈薄片的形態，或亦可為透過任何方法進行過造粒處理之粒狀的形態，但較佳地為總體密度(bulk density)大的衣料之形態。 於經裁剪之薄片的形態下，在操作處理繁雜之同時，總體密度變小，而具有不利於解聚之情形。 雖然在操作的容易性及總體密度的大小上，經造粒處理之粒狀的形態較為有利，但為了將聚酯衣料廢棄物製作成粒狀的形態，根據所採用的方法而有成本增加的情形。Although the form of polyester clothing waste supplied for depolymerization may be in the form of clothing without being cut, it may be in the form of cut sheets, or it may be granulated by any method. It is in the form of a granular form, but preferably in the form of a cloth with a large bulk density. In the form of a cut sheet, the overall density is reduced while the handling is complicated, which is unfavorable for deagglomeration. In terms of ease of handling and overall density, the granulated form is advantageous, but in order to make the polyester clothing waste into the form of granules, there is a cost increase depending on the method used. situation.

再者，當將聚酯衣料廢棄物與預定含量比之MEG加入反應槽中並將聚酯衣料廢棄物進行解聚時，較佳地係在將聚酯衣料廢棄物完全浸漬於MEG中的狀態下進行解聚反應。 聚酯纖維之總體密度係在衣料的形態為0.10g/cm3 至0.14g/cm3 (未壓縮)、在薄片的形態為0.08g/cm3 至0.10g/cm3 (未壓縮)。亦即，聚酯纖維之總體密度係在衣料的形態者較薄片的形態者更能維持在高密度値。 因此，為了有效地進行解聚反應，係即使在將聚酯衣料廢棄物完全浸漬於MEG中的情況下，亦可減少MEG的使用量。在將衣料形態的聚酯衣料廢棄物完全浸漬於MEG中進行解聚反應的情況下，相對於聚酯衣料廢棄物的質量，MEG的使用量較佳地為約4.5倍至7.0倍，更佳地為約5.0倍至6.5倍。Furthermore, when the polyester clothing waste and MEG in a predetermined content ratio are added to the reaction tank and the polyester clothing waste is depolymerized, it is preferably in a state where the polyester clothing waste is completely immersed in MEG. depolymerization reaction. The overall density of the polyester fibers is 0.10 g/cm 3 to 0.14 g/cm 3 (uncompressed) in the form of clothing and 0.08 g/cm 3 to 0.10 g/cm 3 (uncompressed) in the form of flakes. That is, the overall density of polyester fibers in the form of clothing can be maintained at a higher density than those in the form of flakes. Therefore, in order to efficiently carry out the depolymerization reaction, even when the polyester clothing waste is completely immersed in MEG, the amount of MEG used can be reduced. When the polyester clothing waste in the form of clothing is completely immersed in MEG for depolymerization reaction, the amount of MEG used is preferably about 4.5 to 7.0 times the mass of the polyester clothing waste, more preferably The ground is about 5.0 times to 6.5 times.

當MEG的使用量過少時，則根據聚酯衣料廢棄物的形狀等，則有無法將聚酯衣料廢棄物充分地浸漬於MEG中，或是解聚反應所需的時間變長，亦或是藉由解聚反應所進行之從聚酯(例如PET)轉換成BHET的轉換率變低的情形。於此情況下，解聚液中容易存在有大量的聚酯寡聚物(oligomer)，且解聚液的黏度呈現出增加的傾向。另一方面，當MEG的使用量過多時，則MEG的精製會在經濟面上變得不利，並且根據反應條件等而有在反應物中產生大量的二乙二醇(diethylene glycol)(以下亦記載為「DEG」)、1,4-二噁烷(dioxane)等雜質之副產物的情形。在使用了此類BHET的情況下，則根據製造條件而恐有所獲得之再生PET的物理性質(特別是軟化點(softening point))顯著降低的疑慮。When the amount of MEG used is too small, depending on the shape of the polyester clothing waste, the polyester clothing waste cannot be sufficiently immersed in MEG, the time required for the depolymerization reaction becomes longer, or the A case where the conversion rate from polyester (eg PET) to BHET by depolymerization becomes low. In this case, a large amount of polyester oligomers are likely to exist in the depolymerization solution, and the viscosity of the depolymerization solution tends to increase. On the other hand, when the amount of MEG used is too large, the purification of MEG becomes economically disadvantageous, and a large amount of diethylene glycol (hereinafter, also referred to as the following) is produced in the reactant depending on the reaction conditions and the like. It is described as a by-product of impurities such as "DEG") and 1,4-dioxane. When such a BHET is used, there is a possibility that the physical properties (particularly, softening point) of the obtained recycled PET may be significantly lowered depending on the production conditions.

作為解聚觸媒，係可列舉例如鹼金屬之氫氧化物、鹼金屬之碳酸鹽、鹼金屬之脂肪酸鹽、鹼金屬之烷氧化物(alkoxide)、鹼土金屬之氫氧化物、鹼土金屬之碳酸鹽、鹼土金屬之脂肪酸鹽、鹼土金屬之烷氧化物、鹼土金屬之氧化物、過渡金屬之氫氧化物、過渡金屬之碳酸鹽、過渡金屬之脂肪酸鹽、過渡金屬之烷氧化物等，且可組合該等之中的一種或兩種以上來使用。透過使用該等解聚觸媒，係可有效地生產BHET。 作為鹼金屬係可列舉例如Li、Na、K等，作為鹼土金屬係可列舉例如Mg、Ca等，作為過渡金屬係可列舉例如Ti、Zn、Mn等。Examples of the depolymerization catalyst include alkali metal hydroxides, alkali metal carbonates, alkali metal fatty acid salts, alkali metal alkoxides, alkaline earth metal hydroxides, and alkaline earth metal carbonic acids. Salts, alkaline earth metal fatty acid salts, alkaline earth metal alkoxides, alkaline earth metal oxides, transition metal hydroxides, transition metal carbonates, transition metal fatty acid salts, transition metal alkoxides, etc., and can be One or two or more of these are used in combination. By using these depolymerization catalysts, BHET can be efficiently produced. As an alkali metal type, Li, Na, K etc. are mentioned, for example, As an alkaline-earth metal type, Mg, Ca, etc. are mentioned, for example, As a transition metal type, Ti, Zn, Mn etc. are mentioned, for example.

解聚時的溫度係較佳地為約180°C至210°C，更佳地為約185°C至200°C。 當將溫度設定在上述範圍時，解聚的時間係較佳地為約1小時至10小時，更佳地為約1.5小時至7小時。 解聚時的環境壓力係較佳地為約60kPa至160kPa。The temperature during depolymerization is preferably about 180°C to 210°C, more preferably about 185°C to 200°C. When the temperature is set within the above range, the time for depolymerization is preferably about 1 hour to 10 hours, more preferably about 1.5 hours to 7 hours. The ambient pressure at the time of depolymerization is preferably about 60 kPa to 160 kPa.

(2) 固形物去除步驟 如上所述，由於聚酯衣料廢棄物大多含有聚酯纖維以外的異物(不溶於聚酯的固體成分)，故根據需要較佳地係自解聚液去除該等異物。 此類異物係可列舉例如棉、烯烴等不同的材料；拉鍊、紐扣、金屬等的固形物；收集廢棄物時混入的諸如玻璃、沙子等固形物之粗大固形物。 該等異物係可藉由利用篩孔為約20網目(mesh)至40網目的粗過濾器來進行過濾以自解聚液一併去除。(2) Solids removal step As described above, since many polyester clothing wastes contain foreign matters other than polyester fibers (solid content insoluble in polyester), it is preferable to remove these foreign matters from the depolymerization solution as necessary. Examples of such foreign substances include various materials such as cotton and olefin; solid substances such as zippers, buttons, and metals; and coarse solid substances such as glass, sand, and other solid substances mixed in during waste collection. These foreign substances can be removed together with the depolymerized liquid by filtering through a coarse filter with a mesh size of about 20 to 40 meshes.

又於聚酯衣料中係有添加約0.3質量%至0.5質量%之不溶於聚酯的氧化鈦作為消光劑之情形。進一步地，以滿足因應了衣料用途所需特性為目的，使用各種不溶於聚酯之添加劑的情形也很多。 該等微小固形物混入再生PET中當然不佳，又根據該等微小固形物的尺寸，則有在處理過程中沉澱或堆積在容器內部或配管內部而阻斷液體流動的可能性，且在處理過程流暢度的面向上，去除該等微小固形物也較佳。 具體而言，係可利用數μm至數十μm尺寸之長纖維過濾器等來進行過濾或進行熱過濾以去除該等微小固形物。In addition, about 0.3 mass % to 0.5 mass % of polyester-insoluble titanium oxide is added as a matting agent to polyester clothing. Furthermore, there are many cases where various polyester-insoluble additives are used for the purpose of satisfying the properties required for the application of clothing. Of course, it is not good to mix these tiny solids into recycled PET, and depending on the size of these tiny solids, they may precipitate or accumulate in the interior of the container or piping during the treatment process, thereby blocking the flow of the liquid. It is also better to remove these tiny solids with the smoothness of the process facing upwards. Specifically, the fine solids can be removed by filtering or thermal filtration using a long-fiber filter having a size of several μm to several tens of μm.

(3) 色素預去除步驟 更進一步地，著色聚酯衣料廢棄物係藉由染料、顏料等色素而被著色。當聚酯衣料廢棄物的著色程度大時，為了更提高最終得到的BHET的純度，較佳地係進行色素預去除步驟。 此外，在下文中，將說明作為代表的最適合聚酯之著色的分散染料之色素。(3) Pigment pre-removal step Furthermore, colored polyester clothing waste is colored with dyes such as dyes and pigments. When the degree of coloration of the polyester clothing waste is large, in order to further improve the purity of the BHET finally obtained, it is preferable to perform a pigment pre-removal step. In addition, in the following, the coloring matter of the disperse dye which is most suitable for coloring of polyester will be described as a representative.

已知當聚酯衣料廢棄物所含的分散染料混入再生聚酯中時，再生聚酯會被著色，特別是黃色度會增加。因此較佳地係在從聚酯衣料廢棄物製造高純度BHET之際，一邊確認聚酯衣料廢棄物所含的分散染料被去除的程度(分散染料的殘留量)，一邊進行去除一部分的分散染料(色素)之操作。 在此，由於分散染料(許多色素)大多是具有含氮原子之發色基的化合物，因此作為用來確認分散染料被去除的程度的方法之一，係可使用測定解聚液(解聚物)或BHET中殘留之氮原子的含量(殘留量)之方法。It is known that when the disperse dye contained in the polyester clothing waste is mixed into the recycled polyester, the recycled polyester is colored, and in particular, the yellowness is increased. Therefore, it is preferable to remove a part of the disperse dye while confirming the degree to which the disperse dye contained in the polyester clothing waste has been removed (residual amount of the disperse dye) when producing high-purity BHET from the polyester clothing waste. (pigment) operation. Here, since disperse dyes (many pigments) are mostly compounds having chromophores containing nitrogen atoms, as one of the methods for confirming the degree of removal of disperse dyes, a depolymerization solution (depolymerization solution) can be measured using ) or the content of residual nitrogen atoms in BHET (residual amount).

本發明人等針對有效去除色素的方法致力研究的結果，獲得以下的洞見：在著色聚酯衣料廢棄物所含的色素來源之氮原子的含量超過900ppm之情況下，使事先去除色素(預去除)後之粗製BHET中殘留的氮原子之含量減少至900ppm以下，再進行後述之各步驟的處理，則可藉此獲得更高純度的BHET。As a result of intensive research on a method for effectively removing pigments, the present inventors have obtained the following insight: when the content of nitrogen atoms derived from pigments contained in colored polyester clothing waste exceeds 900 ppm, the pre-removal (pre-removal) ), the content of nitrogen atoms remaining in the crude BHET is reduced to 900 ppm or less, and the processing in each of the steps described later can be used to obtain a higher-purity BHET.

此色素預去除步驟係可例如以下述的方式來進行。亦即，首先將經過上述解聚步驟及固形物去除步驟之解聚液冷卻至20°C至25°C，並使BHET或聚酯寡聚物的微結晶作為固體成分析出。其後，使用離心沉降式離心分離機(分離板型、臥式螺旋型等)，將離心力設定為2000G以上，對解聚液進行離心分離。藉此得以將析出的固體成分與解聚液中的MEG及溶解在MEG中的色素進行固液分離。透過以上操作係可獲得殘留的氮原子之含量在900ppm以下之BHET或聚酯寡聚物的固體成分(固體狀之解聚物)。This pigment pre-removal step can be carried out, for example, in the following manner. That is, firstly, the depolymerization liquid subjected to the above-mentioned depolymerization step and the solids removal step is cooled to 20°C to 25°C, and the microcrystals of BHET or polyester oligomer are separated out as solid components. After that, the depolymerized liquid is centrifuged by using a centrifugal decanter centrifuge (separating plate type, horizontal screw type, etc.) to set the centrifugal force to 2000 G or more. Thereby, solid-liquid separation of the precipitated solid content, MEG in the depolymerization liquid, and the dye dissolved in MEG can be performed. Through the above operation system, the solid content of BHET or polyester oligomer (solid depolymerization) with the residual nitrogen atom content of 900 ppm or less can be obtained.

此外，若在1次離心沉降分離操作中殘留的氮原子之含量未達到900ppm以下時，則可在獲得的固體成分中進一步添加MEG，再次進行離心沉降分離操作。 另外，只要聚酯衣料廢棄物所含之色素來源的氮原子之含量在900ppm以下，則可省略本步驟(色素預去除步驟)。In addition, if the content of nitrogen atoms remaining in one centrifugal sedimentation operation does not reach 900 ppm or less, MEG may be further added to the obtained solid content, and the centrifugal sedimentation operation may be performed again. In addition, as long as the content of nitrogen atoms derived from dyes contained in polyester clothing waste is 900 ppm or less, this step (preliminary dye removal step) can be omitted.

有關冷卻解聚液使BHET或聚酯寡聚物作為固體成分析出的操作本身就是晶析操作，於前述發明專利文獻1中亦記載了類似的方法。然而，於本步驟之解聚液中存在多種阻礙晶析操作的雜質，且由於在MEG中會發生晶析，故利用晶析操作所獲得之固體成分的結晶形狀極端地差，而成為結晶尺寸非常小的微結晶。 因此，很難用一般已知的結晶過濾分離機或離心過濾式結晶分離機來進行結晶與液體成分的固液分離。相較於此，只要使用離心沉降式離心分離機，則很小的微結晶與液體成分的固液分離也會變得容易進行。The operation of cooling the depolymerized liquid to analyze the BHET or polyester oligomer as a solid component is itself a crystallization operation, and a similar method is also described in the aforementioned Patent Document 1 of the invention. However, in the depolymerization solution in this step, there are various impurities that hinder the crystallization operation, and since crystallization occurs in MEG, the crystal shape of the solid component obtained by the crystallization operation is extremely poor, and the crystal size becomes the crystal size. Very small microcrystals. Therefore, it is difficult to perform solid-liquid separation of crystals and liquid components using a generally known crystallizer or centrifugal filter-type crystallizer. On the other hand, if a centrifugal decanter centrifuge is used, solid-liquid separation of very small microcrystals and liquid components becomes easy.

此外，利用離心沉降式離心分離機分離之MEG及溶解在MEG中的色素等較佳地係透過蒸發操作、蒸餾操作等進行精製(回收)並再利用。 另一方面，染料成分(色素或發色基)較佳地係濃縮為蒸發殘渣、蒸餾殘渣，並作為產業廢棄物來處理。In addition, MEG separated by the centrifugal decanter centrifuge, pigments dissolved in MEG, etc. are preferably purified (recovered) by evaporation operation, distillation operation, etc. and reused. On the other hand, the dye components (pigments or chromophores) are preferably concentrated into evaporation residues and distillation residues and disposed of as industrial wastes.

(4) 濃縮步驟 其次，透過加熱使上述固形物熔融，並在熔融狀態下獲得液態的解聚物(解聚液)。接著，從此解聚液中去除沸點低於BHET之低沸點成分，獲得以BHET及聚酯寡聚物作為主成分之粗製BHET。此外，由於得到的粗製BHET係在熔融狀態下呈黏稠狀的液體，故亦記載為粗製BHET濃縮液。在此，作為低沸點成分主要係可列舉例如MEG或DEG等。又於此粗製BHET濃縮液中，係有著色用色素成分、聚醯胺成分、聚氨酯成分、聚酯共聚成分、在上述固形物去除步驟(2)中無法去除之未滿5μm的超微細氧化鈦等雜質殘留的情形。(4) Concentration step Next, the above-mentioned solid matter is melted by heating, and a liquid depolymerization (depolymerization liquid) is obtained in a molten state. Next, a low-boiling component whose boiling point is lower than BHET is removed from this depolymerization liquid, and a crude BHET containing BHET and polyester oligomer as main components is obtained. In addition, since the obtained crude BHET is a viscous liquid in a molten state, it is also described as a crude BHET concentrate. Here, MEG, DEG, etc. are mentioned as a low boiling point component main system, for example. In addition, the crude BHET concentrate contains coloring pigment components, polyamide components, polyurethane components, polyester copolymer components, and ultrafine titanium oxide less than 5 μm that cannot be removed in the above-mentioned solid matter removal step (2). such as impurities remaining.

在本步驟(4)進行之低沸點成分的去除(蒸發/餾出)係可使用例如各種蒸發器來進行。 特別是為了防止蒸發操作時之BHET及聚酯寡聚物的聚合，故較佳地係在減壓下將粗製BHET濃縮液的溫度設定在130°C以下來進行。 又較佳地係選擇具有使粗製BHET濃縮液在蒸發器中的滯留時間為10分鐘以下之構造(型式)的蒸發器。 具體的蒸發器係可列舉例如流下膜式蒸發器、薄膜式蒸發器。The removal (evaporation/distillation) of the low-boiling point component in this step (4) can be performed using, for example, various evaporators. In particular, in order to prevent the polymerization of BHET and polyester oligomers during the evaporation operation, it is preferable to carry out under reduced pressure by setting the temperature of the crude BHET concentrate to 130°C or lower. It is also preferable to select an evaporator having a structure (type) that allows the residence time of the crude BHET concentrate in the evaporator to be 10 minutes or less. As a specific evaporator, a flow-down film evaporator and a thin film evaporator are mentioned, for example.

(5) 回收步驟 接下來，以BHET及聚酯寡聚物作為主成分，根據情況係自含有殘留著色用色素成分、殘留聚醯胺成分、殘留聚氨酯成分、殘留聚酯共聚成分、殘留氧化鈦等雜質之粗製BHET濃縮液回收BHET，以獲得BHET純度高於粗製BHET濃縮液之中純度BHET。 BHET之回收係藉由在真空(減壓)下蒸發(以下亦記載為「真空蒸發」)而得以順利地進行。於此情況下，雖然作為真空蒸發的成分係大多為BHET，但亦有與BHET同時被餾出之微量的著色用色素成分、聚酯寡聚物成分、聚醯胺成分、聚氨酯成分、聚酯共聚成分等具有沸點之有機化合物(以下亦記載為「具有沸點的有機化合物」)的情形。(5) Recovery step Next, with BHET and polyester oligomer as the main components, the crude BHET containing impurities such as residual coloring pigment components, residual polyamide components, residual polyurethane components, residual polyester copolymer components, and residual titanium oxide, etc. The BHET is recovered from the concentrate to obtain a higher BHET purity than in the crude BHET concentrate. The recovery of BHET is carried out smoothly by evaporation under vacuum (reduced pressure) (hereinafter also referred to as "vacuum evaporation"). In this case, although most of the components to be evaporated in vacuum are BHET, there are also trace amounts of coloring dye components, polyester oligomer components, polyamide components, polyurethane components, polyester components that are distilled off together with BHET. In the case of an organic compound having a boiling point such as a copolymerization component (hereinafter also referred to as "an organic compound having a boiling point").

具有該等沸點之有機化合物的餾出量係依據在真空蒸發的操作中之溫度、壓力(真空度)以及粗製BHET濃縮液中之具有沸點的有機化合物之殘留莫耳濃度而決定。因此，從製造更高純度的BHET的觀點來看，較佳地係在本步驟(5)之前的步驟中盡可能地去除具有沸點的有機化合物。 在具有沸點的有機化合物中，由於著色用色素成分(分散染料等)係具有在低於沸點的溫度昇華的特性，故只要色素被去除到在供給至本步驟(5)之粗製BHET濃縮液中所殘留的氮原子之含量達到900ppm以下為止時，則可避免在本步驟(5)得到的中純度BHET中混入大量的色素之問題。The distillate amount of the organic compound having the boiling point is determined according to the temperature, pressure (vacuum degree) and the residual molar concentration of the organic compound having the boiling point in the crude BHET concentrate in the operation of vacuum evaporation. Therefore, from the viewpoint of producing higher-purity BHET, it is preferable to remove the organic compound having a boiling point as much as possible in the step before this step (5). Among the organic compounds having a boiling point, since the coloring pigment components (disperse dyes, etc.) have the property of subliming at a temperature lower than the boiling point, as long as the pigment is removed to the crude BHET concentrate supplied to this step (5) When the content of the remaining nitrogen atoms is 900 ppm or less, the problem of mixing a large amount of dyes into the medium-purity BHET obtained in this step (5) can be avoided.

於本步驟(5)進行之BHET的真空蒸發係可遵循發明專利文獻1所記載的薄膜蒸發器的溫度、壓力、滯留時間等條件來進行。但為了盡可能降低著色用色素成分的昇華量，較佳地係更加降低薄膜蒸發器的溫度及壓力。 在本步驟(5)獲得之中純度BHET中殘留的氮原子之含量係較佳地為300ppm以下，更較佳地為200ppm以下。The vacuum evaporation system of BHET performed in this step (5) can be performed under the conditions of the temperature, pressure, residence time, etc. of the thin film evaporator described in Patent Document 1 of the invention. However, in order to reduce the sublimation amount of the coloring pigment component as much as possible, it is preferable to further lower the temperature and pressure of the thin-film evaporator. The content of nitrogen atoms remaining in the intermediate-purity BHET obtained in this step (5) is preferably 300 ppm or less, more preferably 200 ppm or less.

藉由例如真空蒸發而自粗製BHET(粗製BHET濃縮液)回收BHET，以獲得中純度BHET。未完全蒸發之具有沸點的有機化合物及不具有沸點的氧化鈦等固形物係作為蒸發器的殘渣而被排出至系統外。較佳地，被排出的殘渣係透過額外處理而予以有效利用。 亦即，本步驟(5)也可以說是亦擔當作為不具有沸點之固形物的最終分離步驟的角色。BHET is recovered from crude BHET (crude BHET concentrate) by eg vacuum evaporation to obtain BHET of medium purity. The organic compounds having a boiling point that are not completely evaporated, and solids such as titanium oxide that does not have a boiling point are discharged to the outside of the system as residues of the evaporator. Preferably, the discharged residue is effectively utilized through additional processing. That is, this step (5) can be said to also play a role as a final separation step for solids having no boiling point.

(6) 晶析分離步驟 接著，自中純度BHET去除色素以獲得BHET純度高於中純度BHET之精製BHET。 在此，較佳地係將以最終獲得之高純度BHET作為原料並進行聚縮合(熔融聚縮合)所製造的再生聚對苯二甲酸乙二酯之色彩b值(黃色度)設定在8以下。為此，高純度BHET中殘留的氮原子之含量較佳地係在20ppm以下，更較佳地係在10ppm以下。 本發明人等研發得知，為了將高純度BHET中殘留的氮原子之含量調整至上述範圍，在本步驟(6)得到的精製BHET中殘留的氮原子之含量亦同樣地設定在20ppm以下是有效的。(6) Crystallization separation step Next, the pigment is removed from the medium-purity BHET to obtain a refined BHET having a higher BHET purity than the medium-purity BHET. Here, the color b value (yellowness) of the recycled polyethylene terephthalate produced by polycondensation (melt polycondensation) using the finally obtained high-purity BHET as a raw material is preferably set to 8 or less . For this reason, the content of nitrogen atoms remaining in the high-purity BHET is preferably 20 ppm or less, more preferably 10 ppm or less. The inventors of the present invention have found out that, in order to adjust the content of nitrogen atoms remaining in the high-purity BHET to the above range, the content of nitrogen atoms remaining in the purified BHET obtained in this step (6) is similarly set to 20 ppm or less. Effective.

此外，從更降低再生聚對苯二甲酸乙二酯之著色的程度之觀點來看，高純度BHET中殘留的氮原子之含量是盡可能地越少越好。然而，當微量的氮原子殘留在再生聚對苯二甲酸乙二酯時，則具有例如可作為表示是自著色聚酯衣料廢棄物再生的聚對苯二甲酸乙二酯之足跡標記(footprint mark)等加以利用等好處。In addition, from the viewpoint of further reducing the degree of coloration of the regenerated polyethylene terephthalate, the content of nitrogen atoms remaining in the high-purity BHET should be as small as possible. However, when a trace amount of nitrogen atoms remain in the recycled polyethylene terephthalate, for example, it has a footprint mark that can be used as a polyethylene terephthalate regenerated from a self-colored polyester clothing waste. ), etc. to be used and other benefits.

本發明人等針對有效地去除在上述回收步驟(5)中所獲得之中純度BHET中殘留的色素及其他微量的具有沸點之有機化合物等雜質的方法致力研究的結果，研發出以下的方法最為合適。 亦即，較佳地係透過利用對於色素、發色基、具有沸點的有機化合物等之溶解能力(溶解度)大的溶劑(本發明的脫色溶劑)，並冷卻已將中純度BHET溶解於脫色溶劑之溶解液，使BHET的結晶析出，並執行將結晶與含有色素的溶劑成分進行固液分離的操作(以下亦記載為「組合晶析操作」)。 又於晶析之際，係藉由因應脫色溶劑的種類來調整中純度BHET與脫色溶劑的混合比例，而得以更有效地去除上述雜質。The inventors of the present invention, as a result of intensive research on a method for effectively removing impurities such as pigments and other trace organic compounds having a boiling point remaining in the medium-purity BHET obtained in the above recovery step (5), have developed the following method that is the most suitable. That is, it is preferable to dissolve the medium-purity BHET in the decolorizing solvent by using a solvent (the decolorizing solvent of the present invention) having a large dissolving power (solubility) for a pigment, a chromophore, an organic compound having a boiling point, etc., and cooling it. In the solution, the crystal of BHET is precipitated, and the operation of solid-liquid separation of the crystal and the solvent component containing the pigment (hereinafter also referred to as "combination crystallization operation") is performed. During crystallization, the above impurities can be removed more effectively by adjusting the mixing ratio of the medium-purity BHET and the decolorizing solvent according to the type of the decolorizing solvent.

從本發明人等針對色素、發色基、具有沸點的有機化合物等實施溶解度測試的結果證實，作為脫色溶劑係乙二醇類化合物較為適合。 作為乙二醇類化合物係可列舉乙二醇單醚(glycol monoether)、乙二醇二醚(glycol diether)、乙二醇(glycol)，且可組合該等之中的一種或兩種以上來使用。From the results of the solubility test conducted by the present inventors on pigments, chromophores, organic compounds having a boiling point, etc., it has been confirmed that ethylene glycol-based compounds are suitable as decolorizing solvents. Examples of glycol-based compounds include glycol monoether, glycol diether, and glycol, and one or two or more of these may be used in combination. use.

作為乙二醇單醚的具體例係可列舉例如乙二醇單甲醚(ethylene glycol monomethyl ether)、二乙二醇單甲醚(diethylene glycol monomethyl ether)、三乙二醇單甲醚(triethylene glycol monomethyl ether)、乙二醇單異丙醚(ethylene glycol monoisopropyl ether)、二乙二醇單異丙醚(diethylene glycol monoisopropyl ether)、乙二醇單丁醚(ethylene glycol monobutyl ether)、二乙二醇單丁醚(diethylene glycol monobutyl ether)、三乙二醇單丁醚(triethylene glycol monobutyl ether)、乙二醇單異丁醚(ethylene glycol monoisobutyl ether)、二乙二醇單異丁醚(diethylene glycol monoisobutyl ether)、乙二醇單己醚(ethylene glycol monohexyl ether)、二乙二醇單己醚(diethylene glycol monohexyl ether)、丙二醇單甲醚(propylene glycol monomethyl ether)、二丙二醇單甲醚(dipropylene glycol monomethyl ether)、三丙二醇單甲醚(tripropylene glycol monomethyl ether)、丙二醇單丙醚(propylene glycol monopropyl ether)、二丙二醇單丙醚(dipropylene glycol monopropyl ether)、丙二醇單丁醚(propylene glycol monobutyl ether)、二丙二醇單丁醚(dipropylene glycol monobutyl ether)等。Specific examples of the ethylene glycol monoether include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, and triethylene glycol monomethyl ether. monomethyl ether), ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol Monobutyl ether (diethylene glycol monobutyl ether), triethylene glycol monobutyl ether (triethylene glycol monobutyl ether), ethylene glycol monoisobutyl ether (ethylene glycol monoisobutyl ether), diethylene glycol monoisobutyl ether (diethylene glycol monoisobutyl ether) ether), ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether ether), tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether Propylene glycol monobutyl ether, etc.

作為乙二醇二醚的具體例係可列舉例如乙二醇二甲醚(ethylene glycol dimethyl ether)、乙二醇二***(ethylene glycol diethyl ether)、乙二醇二丁醚(ethylene glycol dibutyl ether)、二乙二醇二甲醚(diethylene glycol dimethyl ether)、二乙二醇二***(diethylene glycol diethyl ether)、二乙二醇二丁醚(diethylene glycol dibutyl ether)、三乙二醇二甲醚(triethylene glycol dimethyl ether)、三乙二醇二***(triethylene glycol diethyl ether)、三乙二醇二丁醚(triethylene glycol dibutyl ether)、四乙二醇二甲醚(tetraethylene glycol dimethyl ether)、四乙二醇二***(tetraethylene glycol diethyl ether)、四乙二醇二丁醚(tetraethylene glycol dibutyl ether)、丙二醇二甲醚(propylene glycol dimethyl ether)、丙二醇二***(propylene glycol diethyl ether)、二丙二醇二甲醚(dipropylene glycol dimethyl ether)、二丙二醇二***(dipropylene glycol diethyl ether)等。Specific examples of the glycol diether include, for example, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and ethylene glycol dibutyl ether. , diethylene glycol dimethyl ether (diethylene glycol dimethyl ether), diethylene glycol diethyl ether (diethylene glycol diethyl ether), diethylene glycol dibutyl ether (diethylene glycol dibutyl ether), triethylene glycol dimethyl ether ( triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether (dipropylene glycol dimethyl ether), dipropylene glycol diethyl ether, etc.

作為乙二醇的具體例係可列舉例如乙二醇(ethylene glycol)、二乙二醇(diethylene glycol)、三乙二醇(triethylene glycol)、1,2-丙二醇(propylene glycol)、1,3-丙二醇、1,3-丁二醇(butanediol)、1,4-丁二醇、新戊二醇(neopentyl glycol)、1,5 -戊二醇(pentanediol)、1,6-己二醇(hexanediol)、環己二醇(cyclohexanediole)等。Specific examples of ethylene glycol include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3 -Propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol ( hexanediol), cyclohexanediol (cyclohexanediole), etc.

又，乙二醇單醚及乙二醇二醚各自的碳原子數較佳地係4至12、更佳地係4至10、再更佳地係4至8。另一方面，乙二醇的碳原子數較佳地係2至6。 亦即，脫色溶劑(本發明的脫色溶劑)較佳地係含有選自由碳原子數為4至12之乙二醇單醚或乙二醇二醚，以及碳原子數為2至6之乙二醇所構成的群組之至少一種的乙二醇類化合物。藉由使用含有此類乙二醇類化合物之脫色溶劑，則可進一步提高對殘留在中純度BHET中的色素、發色基、具有沸點的有機化合物等之雜質的去除功效。 於該等之中，從不論著色聚酯衣料廢棄物(中純度BHET)的著色之程度如何皆能展現優異的脫色功效之觀點來看，更佳地係乙二醇單醚。Further, the number of carbon atoms in each of the ethylene glycol monoether and the ethylene glycol diether is preferably 4 to 12, more preferably 4 to 10, and still more preferably 4 to 8. On the other hand, the carbon number of ethylene glycol is preferably 2 to 6. That is, the decolorizing solvent (the decolorizing solvent of the present invention) preferably contains ethylene glycol monoether or ethylene glycol diether having 4 to 12 carbon atoms, and ethylene glycol having 2 to 6 carbon atoms. At least one ethylene glycol compound selected from the group consisting of alcohols. By using a decolorizing solvent containing such ethylene glycol compounds, the removal efficiency of impurities such as pigments, chromophores, and organic compounds with boiling points remaining in the medium-purity BHET can be further improved. Among them, ethylene glycol monoether is more preferable from the viewpoint of exhibiting excellent decolorizing effect regardless of the degree of coloration of the colored polyester clothing waste (medium-purity BHET).

此外，於脫色溶劑中，除了乙二醇類化合物之外，亦可混合水或苯(benzene)、甲苯(toluene)、二甲苯(xylene)、二***(diethyl ether)、乙酸乙酯(ethyl acetate)、丙酮(acetone)等之有機溶劑。 脫色溶劑中之乙二醇類化合物的含量較佳地為85質量%以上，更佳地為90質量%以上，再更佳地為95質量%以上。此外，含量的上限為100質量%。以此含量含有乙二醇類化合物之脫色溶劑係發揮極好的色素去除能力(脫色功效)。 此外，關於溶解液的冷卻溫度，從減少溶解在脫色溶劑中之BHET的量並增加BHET的產率之觀點來看，較佳地係具有較低的冷卻溫度。但考量到冷卻所需的能量、因溫度降低所伴隨之脫色溶劑的黏度增加而導致固液分離的操作性等，冷卻溫度較佳地係設定在約20°C至25°C。 再者，雖然溶解液亦可快速冷卻，但從欲獲得具有足夠尺寸之BHET的結晶之觀點來看，較佳地係緩慢冷卻(包括自然冷卻)。In addition, in the decolorizing solvent, in addition to ethylene glycol compounds, water, benzene, toluene, xylene, diethyl ether and ethyl acetate can also be mixed. ), acetone (acetone) and other organic solvents. The content of the glycol-based compound in the decolorizing solvent is preferably 85% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. Moreover, the upper limit of content is 100 mass %. The decolorizing solvent system containing ethylene glycol compounds in this content exhibits excellent pigment removal ability (decolorization effect). Furthermore, regarding the cooling temperature of the dissolving liquid, it is preferable to have a lower cooling temperature from the viewpoint of reducing the amount of BHET dissolved in the decolorizing solvent and increasing the yield of BHET. However, the cooling temperature is preferably set at about 20°C to 25°C in consideration of the energy required for cooling, the operability of solid-liquid separation due to an increase in the viscosity of the decolorizing solvent accompanying the temperature drop, and the like. Furthermore, although the solution may be rapidly cooled, slow cooling (including natural cooling) is preferable from the viewpoint of obtaining crystals of BHET having a sufficient size.

雖然未特別限定針對進行組合晶析操作的次數，但較佳地係當在第一次的操作中所獲得之精製BHET中殘留的氮原子之含量超過20ppm時，再次進行組合晶析操作。 本發明人等已確認，只要組合晶析操作進行至少3次，則無論著色的程度如何，在精製BHET中殘留之氮原子的含量會在20ppm以下。The number of times the combined crystallization operation is performed is not particularly limited, but when the content of nitrogen atoms remaining in the purified BHET obtained in the first operation exceeds 20 ppm, the combined crystallization operation is preferably performed again. The inventors of the present invention have confirmed that if the combined crystallization operation is performed at least three times, the content of nitrogen atoms remaining in the purified BHET will be 20 ppm or less regardless of the degree of coloration.

含有利用組合晶析操作固液分離的色素、發色基、具有沸點的有機化合物等雜質的脫色溶劑，較佳地係透過蒸發操作、蒸餾操作等進行精製且再利用。 另一方面，色素、發色基、具有沸點的有機化合物等之雜質係較佳地作為蒸發殘渣、蒸餾殘渣來回收，並作為產業廢棄物來處理。 在如上述的本步驟(6)中，係實施了本發明的BHET之精製方法。The decolorizing solvent containing impurities such as dyes, chromophores, and organic compounds having a boiling point separated by solid-liquid separation by combined crystallization operation is preferably purified and reused by evaporation operation, distillation operation, or the like. On the other hand, impurities such as dyes, chromophores, and organic compounds having a boiling point are preferably recovered as evaporation residues and distillation residues, and disposed of as industrial wastes. In this step (6) as described above, the method for purifying BHET of the present invention is carried out.

需要說明的是，亦可考慮使用本發明的脫色溶劑在將著色聚酯衣料廢棄物進行解聚之前，先進行脫色的方法。但在此情況下，聚酯衣料(聚酯纖維)中會殘留有脫色溶劑。具體而言，在聚酯衣料中，相對於衣料的質量，會殘留約3.5倍至4.0倍的脫色溶劑。當聚酯衣料在此狀態下進行解聚時，根據脫色溶劑的種類(例如醚類化合物)則會與聚酯的苯環末端進行反應而不是與MEG進行反應，並使副反應物的生成量增加而不是BHET的生成量增加。本發明人等已證實，當反應發生時，會生成約10%至12%的副反應物，且會降低約10%至12%的BHET的產率。In addition, the method of decolorizing before depolymerizing the colored polyester clothing waste using the decolorizing solvent of this invention can also be considered. However, in this case, the decolorizing solvent remains in the polyester fabric (polyester fiber). Specifically, in polyester clothing, about 3.5 to 4.0 times the amount of decolorizing solvent remains with respect to the mass of the clothing. When the polyester clothing is depolymerized in this state, depending on the type of decolorizing solvent (such as ether compounds), it will react with the benzene ring end of the polyester instead of the MEG, and the amount of side reactants generated will be reduced. Increased rather than increased generation of BHET. The present inventors have confirmed that when the reaction occurs, about 10% to 12% of side reactants are formed, and the yield of BHET is reduced by about 10% to 12%.

為了避免BHET的產率降低，以下的方法也被納入考量：利用聚酯衣料的質量之約20倍至25倍的清洗劑(例如MEG)將脫色後的聚酯衣料清洗後再進行解聚之方法。然而，在此情況下，由於會使用大量的清洗劑而使高純度BHET的製造成本變得過高。再者，本發明人等亦證實，當減少使用於清洗的清洗劑的量或次數時，與不使用清洗劑的情況相比，雖然BHET的產率會提高，但從所獲得的BHET所製造之再生聚對苯二甲酸乙二酯的色彩b值會變為13以上，而使黃化的程度顯著惡化。In order to avoid the decrease in the yield of BHET, the following method is also considered: use a cleaning agent (such as MEG) about 20 times to 25 times the mass of the polyester fabric to wash the decolorized polyester fabric, and then depolymerize it. method. However, in this case, since a large amount of cleaning agent is used, the manufacturing cost of high-purity BHET becomes too high. Furthermore, the present inventors have also confirmed that when the amount or number of times of the cleaning agent used for cleaning is reduced, compared with the case where the cleaning agent is not used, the yield of BHET is improved, but the BHET obtained from the obtained BHET is produced. The color b value of the recycled polyethylene terephthalate will become more than 13, and the degree of yellowing will be significantly deteriorated.

相較於此，以本發明的方式，在先利用MEG將著色聚酯衣料廢棄物進行解聚，再回收BHET(分子蒸餾)獲得中純度BHET(回收步驟)，其後利用脫色溶劑將中純度BHET中殘留的色素進行萃取去除(晶析分離步驟)之方法中，不會生成副產物或是高度抑制副產物的生成，藉此得以提高BHET的產率。 又藉由本發明，由於BHET的晶析與BHET及色素的分離係在一個晶析分離步驟(6)中進行，故色素或發色基難以混入BHET的結晶中，而容易製造更高純度的結晶(BHET)。Compared with this, in the method of the present invention, MEG is used to depolymerize the colored polyester clothing waste, and then BHET is recovered (molecular distillation) to obtain medium-purity BHET (recovery step), and then the medium-purity BHET is obtained by using a decolorizing solvent. In the method of extracting and removing the pigment remaining in BHET (crystallization separation step), no by-products are generated or the generation of by-products is highly suppressed, thereby improving the yield of BHET. Also by the present invention, since the crystallization of BHET and the separation of BHET and pigment are carried out in one crystallization separation step (6), it is difficult for pigment or chromophoric group to be mixed into the crystal of BHET, and it is easy to produce a crystal of higher purity. (BHET).

(7) 脫溶劑步驟 接著，將晶析分離步驟中得到的BHET結晶中殘留之溶劑成分去除，以獲得BHET純度高於精製BHET的高純度BHET。 於本步驟(7)中進行之溶劑成分的去除(蒸發/餾出)係可使用例如各種蒸發器來進行。 特別是為了防止在蒸發操作時之高純度BHET的聚合反應(polymerization)，蒸發器的溫度、壓力係較低者為佳。(7) Desolvation step Next, the solvent components remaining in the BHET crystals obtained in the crystallization separation step are removed to obtain high-purity BHET with a higher BHET purity than purified BHET. The removal (evaporation/distillation) of the solvent component performed in this step (7) can be performed using, for example, various evaporators. In particular, in order to prevent the polymerization of high-purity BHET during the evaporation operation, the temperature and pressure of the evaporator are preferably lower.

以熔融狀態得到之高純度BHET係可直接進行聚縮合(熔融聚縮合)來製造再生聚對苯二甲酸乙二酯，亦可將以熔融狀態得到之高純度BHET先造粒後再進行聚縮合(熔融聚縮合)來製造再生聚對苯二甲酸乙二酯。亦即，本發明的再生聚對苯二甲酸乙二酯為高純度BHET之聚縮合物。 在透過聚縮合製造再生聚對苯二甲酸乙二酯之際，以任意的比例混合高純度BHET與對苯二甲酸，藉此得以容易地製造再生聚對苯二甲酸乙二酯。於此情況下，為了有助於可持續性封閉式再生循環之建立，再生聚對苯二甲酸乙二酯中之高純度BHET來源的結構較佳地係含有50質量%以上、更佳地係含有65質量%以上、再更佳地係含有80質量%以上。The high-purity BHET obtained in the molten state can be directly subjected to polycondensation (melt polycondensation) to produce recycled polyethylene terephthalate, or the high-purity BHET obtained in the molten state can be granulated first and then polycondensed. (melt polycondensation) to manufacture recycled polyethylene terephthalate. That is, the recycled polyethylene terephthalate of the present invention is a polycondensate of high-purity BHET. When producing regenerated polyethylene terephthalate by polycondensation, high-purity BHET and terephthalic acid are mixed in an arbitrary ratio, whereby regenerated polyethylene terephthalate can be easily produced. In this case, in order to contribute to the establishment of a sustainable closed regeneration cycle, the structure of the high-purity BHET source in the recycled polyethylene terephthalate preferably contains more than 50% by mass, more preferably It contains 65 mass % or more, More preferably, it contains 80 mass % or more.

以上雖然針對本發明之高純度BHET的製造方法、再生PET、脫色溶劑以及BHET的精製方法進行了說明，但本發明並非限定於該等者。 本發明之高純度BHET的製造方法及BHET的精製方法係可例如分別與可發揮相同功效的任何步驟置換，亦可追加任何目的的步驟。另外，本發明的步驟亦可為批次式(batch type)、連續式或其等組合之任一者。 又，本發明之再生PET及脫色溶劑係可分別與可發揮相同功效之任何的組成置換，亦可追加任何的組成。 [實施例]The method for producing high-purity BHET, the recycled PET, the decolorizing solvent, and the method for purifying BHET of the present invention have been described above, but the present invention is not limited to these. For example, the method for producing high-purity BHET and the method for purifying BHET of the present invention may be replaced with any step that can exert the same effect, or may be added with any purpose. In addition, the steps of the present invention can also be any one of batch type, continuous type, or a combination thereof. In addition, the recycled PET and the decolorizing solvent system of the present invention may be replaced with any composition that can exert the same effect, and any composition may be added. [Example]

以下係透過實施例以針對本發明的內容更具體地進行說明。需要說明的是，本發明並非限定於該等實施例者。The following is a more specific description of the content of the present invention through embodiments. In addition, this invention is not limited to these Examples.

1. 來自著色聚酯衣料廢棄物之高純度BHET以及再生PET的製造 (實施例1) ＜(1) 解聚步驟＞ 首先，準備了四件總計400g(總體密度：0.12g/cm3 ；於著色衣料廢棄物中含有的氮原子之總含量：1,150ppm)之未經裁剪的藉由黑色分散染料、藍色分散染料、紅色分散染料以及黃色分散染料而被著色之PET衣料廢棄物(以下亦記載為「著色衣料廢棄物」)。 接著，將該等呈衣料的形態之著色衣料廢棄物投入5L的燒瓶(flask)後，將2,245g之已預先加熱至195°C的MEG及1g之作為解聚觸媒的氫氧化鈉(sodium hydroxide)追加投入燒瓶中，於195°C且常壓下不攪拌地進行反應5.0小時。藉此獲得了以經著色之粗製BHET作為主成分的解聚液(著色解聚液)。1. Manufacture of high-purity BHET and recycled PET derived from colored polyester clothing waste (Example 1) <(1) Depolymerization step> First, four pieces of 400 g in total were prepared (overall density: 0.12 g/cm 3 ; Total nitrogen atom content in colored clothing waste: 1,150 ppm) uncut PET clothing waste colored with black disperse dyes, blue disperse dyes, red disperse dyes and yellow disperse dyes (hereinafter also referred to as the Recorded as "colored clothing waste"). Next, after putting these colored clothing wastes in the form of clothing into a 5 L flask, 2,245 g of MEG preheated to 195° C. and 1 g of sodium hydroxide (sodium hydroxide) as a depolymerization catalyst were added. hydroxide) was additionally added to the flask, and the reaction was carried out at 195° C. and normal pressure for 5.0 hours without stirring. Thereby, a depolymerization liquid (colored depolymerization liquid) containing the colored crude BHET as a main component was obtained.

＜(2) 固形物去除步驟＞ 接著，透過篩孔為30網目的金屬網篩過濾器(wire mesh strainer)將著色解聚液進行粗大固形物的熱過濾，得到去除了粗大固形物之著色解聚液。在此階段中，主要去除了PET以外的不同材料(棉、烯烴類)、拉鍊、鈕扣、金屬、玻璃、沙子等粗大固形物。 其次，將著色解聚液的溫度冷卻至95°C，並利用10μm的不鏽鋼製之長纖維過濾器(NASLON過濾器)進行熱過濾，去除了10μm以上之不溶於聚酯的氧化鈦等的微小固形物。<(2) Solid matter removal step> Next, the colored depolymerized liquid was subjected to thermal filtration of coarse solids through a wire mesh strainer having a mesh size of 30 meshes to obtain a colored depolymerized liquid from which the coarse solids were removed. In this stage, various materials other than PET (cotton, olefins), zippers, buttons, metals, glass, sand and other coarse solids are mainly removed. Next, the temperature of the coloring depolymerization solution was cooled to 95°C, and thermal filtration was carried out with a 10 μm stainless steel long fiber filter (NASLON filter) to remove microscopic particles of 10 μm or more, such as titanium oxide insoluble in polyester. solid matter.

＜(3) 色素預去除步驟＞ 接著，將在95°C下通過長纖維過濾器之著色解聚液冷卻至25°C。藉此使BHET或聚酯寡聚物的微結晶作為固體成分析出，利用分離板型(盤型)之離心沉降式離心分離機將被析出的固體成分與解聚液中之MEG及溶解在MEG中的色素進行了固液分離。離心分離機的條件如下：將離心力設定為4,000G，並將離心分離時間設定為30分鐘。 此外，利用離心分離機所分離出之含有色素的MEG的比例，係相對於整體著色解聚液為52質量%，且固體成分中殘留的氮原子之含量為465ppm。<(3) Pigment pre-removal step> Next, the colored depolymerization liquid passed through the long fiber filter at 95°C was cooled to 25°C. In this way, the microcrystals of BHET or polyester oligomer are separated as solid components, and the separated solid components, MEG and MEG in the depolymerization solution are dissolved in a centrifugal decanter centrifuge of separation plate type (disc type). The pigments in MEG were separated from solid and liquid. The conditions of the centrifuge were as follows: the centrifugal force was set to 4,000 G, and the centrifugation time was set to 30 minutes. Moreover, the ratio of the MEG containing pigment|dye isolate|separated by the centrifuge was 52 mass % with respect to the whole coloring depolymerization liquid, and the content of the nitrogen atom remaining in solid content was 465 ppm.

＜(4) 濃縮步驟＞ 接著，藉由將上述固體成分加熱至125°C使其熔融後，送液至薄膜蒸發器中。薄膜蒸發器的條件如下：將夾套加熱(jacket heating)熱媒溫度設定為140°C，且將蒸發器內壓力設定為400Pa(3.0mmHg)。藉此，沸點低於BHET的低沸點成分被蒸發並餾出，而獲得了粗製BHET濃縮液。得到的粗製BHET濃縮液為經著色的黏稠狀之液體。<(4) Concentration step> Next, after melting the above-mentioned solid content by heating to 125° C., it was sent to a thin-film evaporator. The conditions of the thin film evaporator were as follows: the jacket heating heat medium temperature was set to 140° C., and the pressure in the evaporator was set to 400 Pa (3.0 mmHg). Thereby, the low boiling point component whose boiling point is lower than BHET is evaporated and distilled, and the crude BHET concentrated liquid is obtained. The resulting crude BHET concentrate was a colored viscous liquid.

＜(5) 回收步驟＞ 接下來，將粗製BHET濃縮液送液至短行程薄膜蒸發器中。薄膜蒸發器的條件如下：將夾套加熱熱媒溫度設定為180°C，且將蒸發器內壓力設定為10Pa(0.08mmHg)。藉此，使BHET自粗製BHET濃縮液中蒸發並餾出，且回收了中純度BHET。此外，中純度BHET中殘留的氮原子之含量為135ppm。<(5) Recovery step> Next, the crude BHET concentrate is fed into a short stroke thin film evaporator. The conditions of the thin film evaporator were as follows: the temperature of the jacket heating heat medium was set to 180°C, and the pressure in the evaporator was set to 10 Pa (0.08 mmHg). Thereby, BHET was evaporated and distilled from the crude BHET concentrate, and medium-purity BHET was recovered. In addition, the content of nitrogen atoms remaining in the medium-purity BHET was 135 ppm.

＜(6) 晶析分離步驟＞ 其次，將1質量份的中純度BHET與4質量份的作為脫色溶劑之二乙二醇單己醚(碳原子數：10)投入5L的燒瓶中，並加熱至液內溫度達到80℃。藉此將中純度BHET溶解於二乙二醇單己醚中以獲得溶解液。其後，將此溶解液自然冷卻並使液溫降至20°C，以使BHET的結晶析出。 接著，將利用吸濾(Nutsche)型固液分離機析出之BHET的結晶與二乙二醇單己醚進行固液分離，得到了含有殘留脫色溶劑的精製BHET-1。精製BHET-1中殘留的氮原子之含量為52ppm。<(6) Crystallization separation step> Next, 1 part by mass of medium-purity BHET and 4 parts by mass of diethylene glycol monohexyl ether (number of carbon atoms: 10) as a decolorizing solvent were put into a 5 L flask, and heated until the temperature in the liquid reached 80°C. Thereby, the medium-purity BHET was dissolved in diethylene glycol monohexyl ether to obtain a dissolved solution. Thereafter, the dissolved liquid was naturally cooled and the liquid temperature was lowered to 20° C. to precipitate the crystals of BHET. Next, the crystals of BHET precipitated by the Nutsche-type solid-liquid separator were subjected to solid-liquid separation with diethylene glycol monohexyl ether to obtain purified BHET-1 containing a residual decolorizing solvent. The content of nitrogen atoms remaining in the purified BHET-1 was 52 ppm.

進而，將1質量份之含有殘留脫色溶劑的精製BHET-1與4質量份的二乙二醇單己醚投入5L的燒瓶中，進行與上述相同的操作，得到了精製BHET-2。精製BHET-2中殘留的氮原子之含量為22ppm。 更進一步地，再次以與上述相同的方式得到了精製BHET-3。精製BHET-3中殘留的氮原子之含量為9.8ppm。Further, 1 part by mass of purified BHET-1 containing the residual decolorizing solvent and 4 parts by mass of diethylene glycol monohexyl ether were put into a 5 L flask, and the same operation as above was performed to obtain purified BHET-2. The content of nitrogen atoms remaining in the refined BHET-2 was 22 ppm. Further, purified BHET-3 was obtained again in the same manner as above. The content of nitrogen atoms remaining in the purified BHET-3 was 9.8 ppm.

＜(7) 脫溶劑步驟＞ 接下來，透過將含有殘留脫色溶劑之精製BHET-3加熱至125°C使之熔融後，送液至薄膜蒸發器中。薄膜蒸發器的條件如下：將夾套加熱熱媒溫度設定為135°C，且將蒸發器內壓力設定為350Pa(2.6mmHg)。藉此，二乙二醇單己醚被蒸發並餾出，而得到了高純度BHET。得到的高純度BHET為無色​​透明的黏稠狀之液體。再者，高純度BHET中殘留的氮原子之含量為9.2ppm。<(7) Desolvation step> Next, the purified BHET-3 containing the residual decolorizing solvent was heated to 125°C to be melted, and then sent to a thin film evaporator. The conditions of the thin film evaporator were as follows: the temperature of the jacket heating heat medium was set to 135°C, and the pressure in the evaporator was set to 350 Pa (2.6 mmHg). Thereby, diethylene glycol monohexyl ether was evaporated and distilled, and high-purity BHET was obtained. The obtained high-purity BHET is a colorless and transparent viscous liquid. In addition, the content of nitrogen atoms remaining in the high-purity BHET was 9.2 ppm.

其次，將得到的高純度BHET依照常規方法進行熔融聚縮合，而獲得了PET(再生PET)。Next, the obtained high-purity BHET was melt-polycondensed in accordance with a conventional method to obtain PET (recycled PET).

(實施例2) 作為脫色溶劑，除了將二乙二醇單己醚替換成三乙二醇單丁醚(碳原子數：10)來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 2) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 1, except that diethylene glycol monohexyl ether was used instead of triethylene glycol monobutyl ether (number of carbon atoms: 10). .

(實施例3) 作為脫色溶劑，除了將二乙二醇單己醚替換成三丙二醇單甲醚(碳原子數：10)來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 3) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 1, except that diethylene glycol monohexyl ether was used instead of tripropylene glycol monomethyl ether (number of carbon atoms: 10).

(實施例4) 作為脫色溶劑，除了將二乙二醇單己醚替換成乙二醇單己醚(碳原子數：8)來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 4) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 1, except that diethylene glycol monohexyl ether was used instead of ethylene glycol monohexyl ether (number of carbon atoms: 8).

(實施例5) 作為脫色溶劑，除了將二乙二醇單己醚替換成乙二醇單丁醚(碳原子數：6)來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 5) As a decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 1, except that diethylene glycol monohexyl ether was used instead of ethylene glycol monobutyl ether (number of carbon atoms: 6).

(實施例6) 作為脫色溶劑，除了將二乙二醇單己醚替換成三乙二醇單己醚(碳原子數：12)來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 6) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 1, except that triethylene glycol monohexyl ether (number of carbon atoms: 12) was used instead of diethylene glycol monohexyl ether. .

(實施例7) 作為脫色溶劑，除了將二乙二醇單己醚替換成含有85質量份之二乙二醇單甲醚(碳原子數：5)與15質量份之MEG(碳原子數：2)的混合液來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 7) As the decolorizing solvent, except that diethylene glycol monohexyl ether was replaced by a mixed solution containing 85 parts by mass of diethylene glycol monomethyl ether (number of carbon atoms: 5) and 15 parts by mass of MEG (number of carbon atoms: 2) Except for use, high-purity BHET and recycled PET were obtained in the same manner as in Example 1.

(實施例8) 作為脫色溶劑，除了將二乙二醇單己醚替換成含有70質量份之二乙二醇單甲醚(碳原子數：5)與30質量份之MEG的混合液來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 8) As the decolorizing solvent, diethylene glycol monohexyl ether was replaced with a mixed solution containing 70 parts by mass of diethylene glycol monomethyl ether (number of carbon atoms: 5) and 30 parts by mass of MEG. High-purity BHET and recycled PET were obtained in the same manner as in Example 1.

(實施例 9) 將氮原子的總含量為1,150ppm之著色衣料廢棄物替換成氮原子的總含量為850ppm之著色衣料廢棄物來作為原料，且將4質量份的二乙二醇單己醚替換成6.5質量份的MEG來作為脫色溶劑使用，並省略了色素預去除步驟(3)之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 9) Colored clothing waste with a total nitrogen atom content of 1,150 ppm was replaced with colored clothing waste with a total nitrogen atom content of 850 ppm as a raw material, and 4 parts by mass of diethylene glycol monohexyl ether was replaced with 6.5 parts by mass The MEG was used as a decolorizing solvent, and except that the pigment pre-removal step (3) was omitted, high-purity BHET and recycled PET were obtained in the same manner as in Example 1.

(實施例 10) 作為脫色溶劑，除了將MEG替換成二乙二醇(碳原子數：4)來使用之外，以與實施例9相同的方式獲得了高純度BHET以及再生PET。(Example 10) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 9, except that MEG was used instead of diethylene glycol (number of carbon atoms: 4).

(實施例11) 作為脫色溶劑，除了將MEG替換成三乙二醇(碳原子數：6)來使用之外，以與實施例9相同的方式獲得了高純度BHET以及再生PET。(Example 11) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 9, except that MEG was used instead of triethylene glycol (number of carbon atoms: 6).

(實施例12) 作為脫色溶劑，除了將二乙二醇單己醚替換成乙二醇二甲醚(碳原子數：4)來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 12) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 1, except that diethylene glycol monohexyl ether was used instead of ethylene glycol dimethyl ether (number of carbon atoms: 4).

(實施例13) 作為脫色溶劑，除了將二乙二醇單己醚替換成乙二醇單甲醚(碳原子數：3)來使用之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Example 13) As the decolorizing solvent, high-purity BHET and recycled PET were obtained in the same manner as in Example 1, except that diethylene glycol monohexyl ether was used instead of ethylene glycol monomethyl ether (number of carbon atoms: 3).

(比較例1) 首先，在解聚前，使用二乙二醇單己基醚(碳原子數：10)作為脫色溶劑對呈衣料的形態之著色衣料廢棄物進行了脫色。其結果係使脫色溶劑以浸透在經脫色處理的衣料廢棄物之中的狀態下殘留。 接著，當使用MEG對殘留有脫色溶劑之狀態的衣料廢棄物進行解聚時，殘留的醚會與苯環進行鍵結而非與MEG進行鍵結，藉此生成了BHET以外的副反應物。 在本發明人等的測試結果中已證實：相較於實施例的方法(解聚後的脫色)，BHET的產率係因副產物的生成而減少了約10質量%至12質量%。又已證實：為了避免BHET的產率減少，必須利用著色衣料廢棄物的質量之約20倍至25倍的MEG來清洗，故不符合成本效益。 此外，BHET的產率(%)係根據生成的粗製BHET的質量÷(著色衣料廢棄物的質量×(254/192))×100來計算。(Comparative Example 1) First, before depolymerization, the colored clothing waste in the form of clothing was decolorized using diethylene glycol monohexyl ether (number of carbon atoms: 10) as a decolorizing solvent. As a result, the decolorizing solvent remains in a state of being soaked in the decolorized clothing waste. Next, when MEG is used to depolymerize the clothing waste in the state where the decolorizing solvent remains, the residual ether is bonded to the benzene ring instead of the MEG, thereby generating side reactants other than BHET. In the test results of the present inventors, it has been confirmed that the yield of BHET is reduced by about 10 to 12 mass % due to the generation of by-products compared to the method of the Example (decolorization after depolymerization). It has also been confirmed that in order to avoid the decrease in the yield of BHET, it is not cost-effective to use MEG which is about 20 to 25 times the mass of the colored clothing waste. In addition, the yield (%) of BHET was calculated based on the mass of the produced crude BHET÷(mass of colored clothing waste×(254/192))×100.

(比較例2) 除了將4質量份的二乙二醇單己醚替換成6.5質量份的MEG來作為脫色溶劑使用，且省略了回收步驟(5)之外，以與實施例1相同的方式獲得了高純度BHET以及再生PET。(Comparative Example 2) High-purity BHET was obtained in the same manner as in Example 1, except that 4 parts by mass of diethylene glycol monohexyl ether was replaced with 6.5 parts by mass of MEG as the decolorizing solvent, and the recovery step (5) was omitted. and recycled PET.

2. 測定 2-1. 氮原子之含量的測定 著色衣料廢棄物、著色預去除後的固形物、中純度BHET、精製BHET-1至精製BHET-3、以及高純度BHET中殘留的氮原子之含量係分別利用微量總氮分析裝置(trace total nitrogen analyzer)(三菱化學分析科技公司製)「TN-2100H」)進行了測定。 2-2. 色彩b值的測定 再生PET的色彩b值係利用色差計(color-difference meter)(日本電色公司製「SE-7700」)進行了測定。2. Assay 2-1. Determination of nitrogen atom content The content of residual nitrogen atoms in colored clothing waste, solids after coloring pre-removal, medium-purity BHET, refined BHET-1 to refined BHET-3, and high-purity BHET were measured using a trace total nitrogen analyzer. analyzer) (manufactured by Mitsubishi Chemical Analytical Technology Co., Ltd.) "TN-2100H") was measured. 2-2. Measurement of color b value The color b value of the recycled PET was measured with a color-difference meter (“SE-7700” manufactured by Nippon Denshoku Corporation).

以上的結果係統整於表1中表示。The above results are systematically shown in Table 1.

[表1]

Figure 02_image001
[Table 1]
Figure 02_image001

〔圖1〕係顯示本發明之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法之較佳實施態樣的流程圖。[ Fig. 1 ] is a flow chart showing a preferred embodiment of the method for producing high-purity bis-(2-hydroxyethyl) terephthalate of the present invention.

Claims (16)

一種高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其具備： 解聚步驟，係混合藉由色素而被著色之聚酯廢棄物與單乙二醇及解聚觸媒，而將前述聚酯廢棄物進行解聚以獲得含有被著色之粗製雙-(2-羥乙基)對苯二甲酸酯的解聚物的步驟； 濃縮步驟，係自前述解聚物去除含有前述單乙二醇的低沸點成分，而濃縮前述粗製雙-(2-羥乙基)對苯二甲酸酯的步驟； 回收步驟，係自經濃縮之前述粗製雙-(2-羥乙基)對苯二甲酸酯回收前述雙-(2-羥乙基)對苯二甲酸酯，以獲得純度高於前述粗製雙-(2-羥乙基)對苯二甲酸酯之中純度雙-(2-羥乙基)對苯二甲酸酯的步驟； 晶析分離步驟，係藉由將前述中純度雙-(2-羥乙基)對苯二甲酸酯溶解於脫色溶劑之溶解液進行冷卻，而使前述雙-(2-羥乙基)對苯二甲酸酯的結晶析出，並將前述結晶與含有前述色素之溶劑成分進行固液分離，以獲得純度高於前述中純度雙-(2-羥乙基)對苯二甲酸酯之精製雙-(2-羥乙基)對苯二甲酸酯的步驟；以及 脫溶劑步驟，係去除殘留在前述結晶中之前述溶劑成分，以獲得純度高於前述精製雙-(2-羥乙基)對苯二甲酸酯之高純度雙-(2-羥乙基)對苯二甲酸酯的步驟。A kind of manufacture method of high-purity bis-(2-hydroxyethyl) terephthalate, it has: The depolymerization step is to mix the polyester waste colored by the pigment with monoethylene glycol and a depolymerization catalyst, and depolymerize the polyester waste to obtain the colored crude bis-(2- a step of depolymerization of hydroxyethyl) terephthalate; The concentration step is a step of removing the low-boiling component containing the monoethylene glycol from the depolymerization, and concentrating the crude bis-(2-hydroxyethyl) terephthalate; The recovery step is to recover the aforementioned bis-(2-hydroxyethyl) terephthalate from the concentrated aforementioned crude bis-(2-hydroxyethyl) terephthalate, so as to obtain a higher purity than the aforementioned crude bis-(2-hydroxyethyl) terephthalate The step of pure bis-(2-hydroxyethyl) terephthalate in bis-(2-hydroxyethyl) terephthalate; The crystallization separation step is to cool the solution obtained by dissolving the medium-purity bis-(2-hydroxyethyl) terephthalate in a decolorizing solvent, so that the bis-(2-hydroxyethyl) bis-(2-hydroxyethyl) The crystallization of phthalic acid ester is precipitated, and the solid-liquid separation of the above-mentioned crystal and the solvent component containing the above-mentioned pigment is carried out to obtain the purification of bis-(2-hydroxyethyl) terephthalate with a purity higher than the above-mentioned medium purity the step of bis-(2-hydroxyethyl)terephthalate; and The desolvation step is to remove the aforementioned solvent components remaining in the aforementioned crystals to obtain high-purity bis-(2-hydroxyethyl) with a purity higher than the aforementioned purified bis-(2-hydroxyethyl) terephthalate Steps for terephthalates. 如請求項1所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述晶析分離步驟使用的前述脫色溶劑係含有選自由碳原子數為4至12之乙二醇單醚或乙二醇二醚，以及碳原子數為2至6之乙二醇所構成的群組之至少一種的乙二醇類化合物。The method for producing high-purity bis-(2-hydroxyethyl)terephthalate as set forth in claim 1, wherein the decolorizing solvent used in the crystallization and separation step contains a solvent selected from the group consisting of 4 to 4 carbon atoms to 12 ethylene glycol monoether or ethylene glycol diether, and at least one ethylene glycol compound of the group consisting of ethylene glycol with 2 to 6 carbon atoms. 如請求項2所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述晶析分離步驟使用的前述脫色溶劑中之前述乙二醇類化合物的含量係85質量%以上。The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to claim 2, wherein the content of the glycol-based compound in the decolorizing solvent used in the crystallization and separation step The system is more than 85% by mass. 如請求項1至請求項3中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中： 前述色素係具有包含氮原子之發色基； 殘留在前述高純度雙-(2-羥乙基)對苯二甲酸酯中之前述氮原子的含量係20 ppm以下。The method for producing high-purity bis-(2-hydroxyethyl) terephthalate as described in any one of claim 1 to claim 3, wherein: The aforementioned pigment system has a chromophore group containing nitrogen atoms; The content of the aforementioned nitrogen atoms remaining in the aforementioned high-purity bis-(2-hydroxyethyl) terephthalate is 20 ppm or less. 如請求項1至請求項4中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中前述聚酯廢棄物係包括65質量%以上之聚對苯二甲酸乙二酯。The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to any one of claim 1 to claim 4, wherein the polyester waste comprises 65% by mass or more of Polyethylene terephthalate. 如請求項1至請求項5中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中前述聚酯廢棄物係聚酯衣料廢棄物。The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to any one of claim 1 to claim 5, wherein the polyester waste is polyester clothing waste. 如請求項6所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述解聚步驟中係將前述聚酯衣料廢棄物在衣料的形態下進行解聚。The method for producing high-purity bis-(2-hydroxyethyl)terephthalate according to claim 6, wherein in the depolymerization step, the polyester clothing waste is decomposed in the form of clothing poly. 如請求項6或請求項7所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述解聚步驟後係進一步具備固形物去除步驟，前述固形物去除步驟係自前述解聚物去除前述聚酯衣料廢棄物中所含之不溶於聚酯的固體成分。The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to claim 6 or claim 7, wherein after the depolymerization step, a solid matter removal step is further provided, and the solid matter The removal step is to remove the polyester-insoluble solid content contained in the polyester clothing waste from the depolymerization. 如請求項1至請求項8中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中在前述解聚步驟後係進一步具備色素預去除步驟，前述色素預去除步驟係自前述解聚物去除一部分的前述色素。The method for producing high-purity bis-(2-hydroxyethyl) terephthalate according to any one of claim 1 to claim 8, wherein after the depolymerization step, a pre-removal of pigment is further provided step, the aforementioned pigment pre-removal step is to remove a part of the aforementioned pigment from the aforementioned depolymerization. 如請求項9所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法，其中： 前述色素係具有含有氮原子之發色基； 前述色素預去除步驟係進行到殘留在前述解聚物中的前述氮原子的含量成為900 ppm以下為止。The method for producing high-purity bis-(2-hydroxyethyl) terephthalate as described in claim 9, wherein: The aforementioned pigment system has a chromophore group containing nitrogen atoms; The aforementioned dye preliminarily removal step is performed until the content of the aforementioned nitrogen atoms remaining in the aforementioned depolymerization becomes 900 ppm or less. 一種再生聚對苯二甲酸乙二酯，係藉由如請求項1至請求項10中之任一項所記載之高純度雙-(2-羥乙基)對苯二甲酸酯的製造方法而得之高純度雙-(2-羥乙基)對苯二甲酸酯的聚縮合物。A regenerated polyethylene terephthalate, by the method for producing high-purity bis-(2-hydroxyethyl) terephthalate as described in any one of claim 1 to claim 10 The obtained high-purity bis-(2-hydroxyethyl) terephthalate polycondensate. 如請求項11所記載之再生聚對苯二甲酸乙二酯，其中前述再生聚對苯二甲酸乙二酯係含有50質量%以上之源自前述高純度雙-(2-羥乙基)對苯二甲酸酯的結構。The regenerated polyethylene terephthalate according to claim 11, wherein the regenerated polyethylene terephthalate contains 50% by mass or more of bis-(2-hydroxyethyl)paraben derived from the high purity The structure of phthalates. 一種脫色溶劑，係用於自藉由色素而被著色之雙-(2-羥乙基)對苯二甲酸去除前述色素以進行脫色的脫色溶劑，其含有選自由碳原子數為4至12之乙二醇單醚或乙二醇二醚，以及碳原子數為2至6之乙二醇所構成的群組之至少一種的乙二醇類化合物。A decolorizing solvent used for removing the aforementioned pigment from bis-(2-hydroxyethyl) terephthalic acid colored by a pigment to decolorize, which contains a compound selected from the group consisting of 4 to 12 carbon atoms. Ethylene glycol monoether or ethylene glycol diether, and at least one ethylene glycol compound selected from the group consisting of ethylene glycol having 2 to 6 carbon atoms. 如請求項13所記載之脫色溶劑，其中前述脫色溶劑中之前述乙二醇類化合物的含量係85質量%以上。The decolorizing solvent according to claim 13, wherein the content of the glycol-based compound in the decolorizing solvent is 85% by mass or more. 一種雙-(2-羥乙基)對苯二甲酸酯的精製方法，係透過將藉由色素而被著色之雙-(2-羥乙基)對苯二甲酸酯溶解於脫色溶劑之溶解液進行冷卻，而使前述雙-(2-羥乙基)對苯二甲酸酯的結晶析出，並將前述結晶與含有前述色素之溶劑成分進行固液分離，以精製前述雙-(2-羥乙基)對苯二甲酸酯的方法； 前述脫色溶劑係含有選自由碳原子數為4至12之乙二醇單醚或乙二醇二醚，以及碳原子數為2至6之乙二醇所構成的群組之至少一種的乙二醇類化合物。A method for purifying bis-(2-hydroxyethyl) terephthalate by dissolving bis-(2-hydroxyethyl) terephthalate colored by a pigment in a decolorizing solvent. The solution is cooled to precipitate crystals of the aforementioned bis-(2-hydroxyethyl) terephthalate, and the aforementioned crystals and the solvent component containing the aforementioned pigment are subjected to solid-liquid separation to purify the aforementioned bis-(2 - the method for hydroxyethyl) terephthalate; The aforementioned decolorizing solvent contains at least one ethylene glycol selected from the group consisting of ethylene glycol monoether or ethylene glycol diether having 4 to 12 carbon atoms and ethylene glycol having 2 to 6 carbon atoms. Alcohol compounds. 如請求項15所記載之雙-(2-羥乙基)對苯二甲酸酯的精製方法，其中前述脫色溶劑中之前述乙二醇類化合物的含量係85質量%以上。The method for purifying bis-(2-hydroxyethyl)terephthalate according to claim 15, wherein the content of the glycol-based compound in the decolorizing solvent is 85% by mass or more.
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