JP2003055300A - METHOD FOR PRODUCING BIS-beta-HYDROXYETHYL TEREPHTHALATE - Google Patents

METHOD FOR PRODUCING BIS-beta-HYDROXYETHYL TEREPHTHALATE

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Publication number
JP2003055300A
JP2003055300A JP2001247750A JP2001247750A JP2003055300A JP 2003055300 A JP2003055300 A JP 2003055300A JP 2001247750 A JP2001247750 A JP 2001247750A JP 2001247750 A JP2001247750 A JP 2001247750A JP 2003055300 A JP2003055300 A JP 2003055300A
Authority
JP
Japan
Prior art keywords
pet
bhet
ethylene glycol
reaction
depolymerization
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
JP2001247750A
Other languages
Japanese (ja)
Inventor
Shuji Inada
修司 稲田
Kikutomo Sato
菊智 佐藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
IS KK
Original Assignee
IS KK
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by IS KK filed Critical IS KK
Priority to JP2001247750A priority Critical patent/JP2003055300A/en
Publication of JP2003055300A publication Critical patent/JP2003055300A/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • C08J11/18—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 organic material
    • C08J11/22—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 organic material by treatment with organic oxygen-containing compounds
    • C08J11/24—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 organic material by treatment with organic oxygen-containing compounds containing hydroxyl groups
    • 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
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/62—Plastics recycling; Rubber recycling

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing bis-β-hydroxyethyl terephthalate(BHET), by which BHET having an improved quality can be produced in an improved yield without being affected by reaction inhibitors such as water and polyvinyl chloride contained in PET supplied for recycling, while overcoming the heterogeneous low reactivity of solid PET due to shape and crystallization states and ensuring stable high performance productivity and operability. SOLUTION: This method for producing the bis-β-hydroxyethyl terephthalate(BHET) is characterized by melting and degasifying the polyethylene terephthalate(PET), preliminarily depolymerizing the melted PET with ethylene glycol in an amount of 15 to 50 wt.% based on the polyethylene terephthalate, dissolving and reacting the obtained low polymer composition with ethylene glycol in an amount of 2 to 10 weight times that of the polyethylene terephthalate at 180 to 250 deg.C to finish the depolymerization.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、ポリエチレンテレ
フタレート（以下ＰＥＴ）からビス−β−ヒドロキシエ
チルテレフタレート（以下ＢＨＥＴ）を製造する方法お
よび得られたＢＨＥＴからＰＥＴを製造する方法に関す
る。さらに詳しくは、その優れた性能によって、繊維、
フィルム、ボトル、その他の成形用樹脂として広範な用
途に大量に使用されている汎用芳香族ポリエステルであ
るＰＥＴのケミカルリサイクルを効率化し、また品質を
向上させたＰＥＴの製造法に関する。TECHNICAL FIELD The present invention relates to a method for producing bis-β-hydroxyethyl terephthalate (hereinafter referred to as BHET) from polyethylene terephthalate (hereinafter referred to as PET) and a method for producing PET from the obtained BHET. More specifically, due to its excellent performance, fibers,
The present invention relates to a method for producing PET, which is a general-purpose aromatic polyester that has been used in large amounts in a wide range of applications as a resin for molding films, bottles, and the like, and which has improved chemical recycling efficiency and improved quality.

【０００２】[0002]

【従来の技術】ＰＥＴは、テレフタール酸とエチレング
リコールとのエステル化反応か、ジメチルテレフタレー
トとエチレングリコールとのエステル交換反応によりＢ
ＨＥＴを含む低重合体とし、これを高温、高真空下に縮
合重合させる方法で工業的に製造されている。ＰＥＴは
エチレングリコールなどによって解重合して、ほぼ定量
的にその原料段階に回帰することができる。必要に応じ
て精製したのち、再度重合してＰＥＴとして再利用する
ことが可能であり、資源の循環高率活用、節約のはかれ
る優れた材料である。2. Description of the Related Art PET is produced by the esterification reaction of terephthalic acid with ethylene glycol or the transesterification reaction of dimethyl terephthalate with ethylene glycol.
It is industrially produced by a method in which a low polymer containing HET is prepared, and this is subjected to condensation polymerization under high temperature and high vacuum. PET can be depolymerized with ethylene glycol or the like and returned to its raw material stage almost quantitatively. It is an excellent material that can be reused as PET after being purified if necessary after being polymerized again, and can be used at a high recycling rate of resources and can be saved.

【０００３】再利用に供するＰＥＴの解重合は、通常、
ＰＥＴの固体片と過剰量のエチレングリコールを触媒の
存在下に反応させて行っている。固体片には繊維状、チ
ップ状、破砕片、切断片（フレーク）など、それが製造
され使用された分野と回収・集約方法、および解重合の
前処理法によって変わる種々の形状がある。また、同じ
原因で大きく変わる性状の違いがある。解重合に大きな
影響を与える性状としては、種々の不純物と変性に用い
られた化合物の質と量、およびその混在状態、ならびに
ＰＥＴの結晶化度などがある。The depolymerization of PET for reuse is usually carried out.
It is carried out by reacting a solid piece of PET with an excess amount of ethylene glycol in the presence of a catalyst. The solid piece has various shapes such as a fibrous shape, a chip shape, a crushed piece, and a cut piece (flakes), which vary depending on the field in which it is manufactured and used, the method of collecting and collecting, and the pretreatment method of depolymerization. In addition, there are differences in properties that greatly change due to the same cause. Properties that greatly affect depolymerization include various impurities and the quality and amount of the compound used for modification, their mixed state, and the crystallinity of PET.

【０００４】大きな変性を行っていない通常のＰＥＴに
おいて特に問題となるのは、吸着および外部付着してい
る水を別にすれば、不純物として混入するポリ塩化ビニ
ールとＰＥＴ固体の高結晶化状態である。前者はプラス
チック容器の分別回収において外観の似た透明容器とし
て混入しやすく、また、例えばＰＥＴボトルのラベル用
シートなどとして用いられ、切断片であるフレークに混
在してくる。解重合時に触媒と反応してこれを不活性化
し、取り除きにくい塩化物を生成する。後者は繊維を含
む各種ＰＥＴ成形品の形状安定性、高強度、高剛性、耐
熱性、耐薬品性など、その優れた物性を与えるものであ
るが、解重合においてその反応の進行を遅くするととも
に、相対的に副反応を大きくしてしまう。なお、水はエ
チレングリコールによる解重合反応を妨げ、好ましくな
い加水分解を起こしやすい。A particular problem in ordinary PET that has not undergone major modification is the highly crystallized state of polyvinyl chloride and PET solid, which are mixed as impurities, except for water adsorbed and adhering externally. . The former is easily mixed as a transparent container having a similar appearance in the separate collection of plastic containers, and is used as a label sheet for PET bottles, for example, and mixed in flakes which are cut pieces. During depolymerization, it reacts with the catalyst to deactivate it and form chloride, which is difficult to remove. The latter imparts excellent physical properties such as shape stability, high strength, high rigidity, heat resistance, and chemical resistance of various PET molded products containing fibers, but slows the progress of the reaction in depolymerization. , Relatively increases side reactions. It should be noted that water hinders the depolymerization reaction with ethylene glycol and tends to cause undesirable hydrolysis.

【０００５】ＰＥＴ固体片、とくに不純物を含むＰＥＴ
固体片と液状エチレングリコールの反応は、その表面反
応の進行が遅いだけではなく、反応完結時間が不安定
で、予測しにくい。従って、反応装置は大きくなり、操
業がむつかしく、連続化も困難である。また、固体表面
および膨潤した固体表面層で反応して液中に溶け出す
か、表面層にあるモノマー（ＢＨＥＴなど）と低重合体
（以下オリゴマー）が副反応を起こす機会が増え、ジエ
チレングリコール（以下ＤＥＧ）および／またはＤＥＧ
をグリコール成分として含むモノマーとオリゴマー（以
下ＤＥＧＥＳＴＥＲ）、およびＢＨＥＴが一部加水分解
したモノヒドロキシエチルテレフタレートなど（以下Ｍ
ＨＥＴ）が増加する。PET solid pieces, especially PET containing impurities
Regarding the reaction between the solid pieces and the liquid ethylene glycol, not only the surface reaction progresses slowly but also the reaction completion time is unstable, which is difficult to predict. Therefore, the reactor becomes large, the operation is difficult, and it is difficult to make it continuous. In addition, the chances of reacting on the solid surface and the swollen solid surface layer to dissolve in the liquid or to cause side reactions between the monomer (BHET etc.) and the low polymer (hereinafter oligomer) in the surface layer increase, and diethylene glycol (hereinafter DEG) and / or DEG
Monomers and oligomers containing as a glycol component (hereinafter DEGESTER), monohydroxyethyl terephthalate partially hydrolyzed by BHET (hereinafter M
HET) increases.

【０００６】その結果、回収したＢＨＥＴのＤＥＧＥＳ
ＴＥＲ含有量、ＭＨＥＴ合有量、および過剰のエチレン
グリコール中に残るＤＥＧとＤＥＧＥＳＴＥＲ、ならび
にＭＨＥＴの量が増え、ＢＨＥＴの収率と純度・品質、
およびそれを再重合して得られるＰＥＴの品質を低下さ
せ、解重合工程の中で循環使用されるエチレングリコー
ルの原単位と精製コスト増大を招くなど、ＰＥＴのケミ
カルリサイクルを難かしくする不利益を生じさせる。本
発明者は、既に提案した特開２００１−４８８３４号に
おいて、ＰＥＴをＢＨＥＴおよび／またはその低縮合物
と加熱してＰＥＴを予備解重合する方法により、ＰＥＴ
固体の高結晶、高配向部分の反応しにくさによるトラブ
ル（反応時間の不安定、未反応部分の残留等）を解決で
きることを示したが、この方法では上述の問題点の一部
を解消したのみであり、多量のＢＨＥＴを用いないとそ
の利点を十分生かせず、解重合完結反応を均一溶液反応
として行えないというさらに改善すべき点があった。[0006] As a result, the recovered BHET DEGES
The TER content, the MHET content, and the amount of DEG and DEGESTER remaining in excess ethylene glycol, and the amount of MHET are increased, and the yield, purity and quality of BHET,
And the quality of PET obtained by re-polymerizing it is reduced, resulting in an increase in the basic unit of ethylene glycol used in circulation in the depolymerization process and an increase in purification cost, which is a disadvantage that makes chemical recycling of PET difficult. Give rise to. The present inventor has already proposed in JP-A-2001-48834 by a method of heating PET with BHET and / or a low condensate thereof to pre-depolymerize PET to obtain PET.
It was shown that problems (due to unstable reaction time, residual unreacted part, etc.) due to difficulty in reacting solid high crystals and highly oriented parts could be solved, but this method solved some of the above problems. However, if a large amount of BHET is not used, the advantage cannot be fully utilized, and there is a point to be further improved that the depolymerization completion reaction cannot be performed as a homogeneous solution reaction.

【０００７】[0007]

【発明が解決しようとする課題】本発明の目的は、ＰＥ
ＴからそのモノマーであるＢＨＥＴを効率的に製造する
方法を提供することにある。本発明の他の目的は副反応
を抑えて高品質のＢＨＥＴを製造する方法を提供するこ
とにある。本発明のさらに他の目的は、再利用に供する
ＰＥＴに混在する水、ポリ塩化ビニールなどの反応阻害
物の悪影響を除き、形状や結晶化状態によるＰＥＴ固体
の不均一な低い反応性を克服し、安定した高能率の生産
性、操業性を確保できるＢＨＥＴの製造方法を提供する
ことにある。本発明のさらに他の目的は、上記本発明方
法で製造されたＢＨＥＴから高品質のＰＥＴを製造する
方法を提供することにある。本発明のさらに他の目的と
利点は、以下の説明から明らかとなろう。The object of the present invention is to provide PE
It is intended to provide a method for efficiently producing BHET which is a monomer thereof from T. Another object of the present invention is to provide a method for producing high-quality BHET by suppressing side reactions. Still another object of the present invention is to overcome the adverse effects of water, polyvinyl chloride, and other reaction inhibitors mixed in PET for reuse, overcoming the non-uniform low reactivity of PET solids due to shape and crystallization state. Another object of the present invention is to provide a BHET manufacturing method capable of ensuring stable and highly efficient productivity and operability. Still another object of the present invention is to provide a method for producing high quality PET from BHET produced by the above-mentioned method of the present invention. Further objects and advantages of the present invention will be apparent from the following description.

【０００８】[0008]

【課題を解決するための手段】本発明の上記目的および
利点は、ＰＥＴを溶融および脱ガスし、該ＰＥＴの１５
乃至５０重量％に当る量のエチレングリコールを、解重
合触媒の存在下に予備解重合反応させて低重合体組成物
とし、次いでこの低重合体組成物をＰＥＴの２乃至１０
重量倍のエチレングリコールに溶解して１８０乃至２５
０℃において反応させ、解重合を完結することを特徴と
するＢＨＥＴの製造法によって達成される。The above objects and advantages of the present invention are to melt and degas PET and
To 50% by weight of ethylene glycol is pre-depolymerized in the presence of a depolymerization catalyst to obtain a low polymer composition, and the low polymer composition is then added to PET in an amount of 2 to 10%.
180 to 25 by dissolving in ethylene glycol by weight
This is achieved by a method for producing BHET, which comprises reacting at 0 ° C. to complete depolymerization.

【０００９】本発明者は、従来の解重合方法の原料ＰＥ
Ｔによる不安定要因を十分に取り除くには、原料ＰＥＴ
を高温度で溶融し、低沸点化合物（水、塩酸等）を除去
すればよいこと、一方、副反応を抑制しつつ、生産性
（速度と安定度）の高い反応工程とするためには、解重
合をできるだけ低温で均一溶液反応として行うとよいこ
とを見出し、さらに両要件を併せて実現できる方法につ
いて鋭意検討の結果、溶融・脱ガスした溶融状態のポリ
マーを、触媒と少量のエチレングリコールと急速反応さ
せ、２５０℃以下の温度のエチレングリコールに可溶の
オリゴマーとすればよいことを突き止め、本発明を完成
するに到ったものである。本発明方法によって得られる
品質と生産性向上効果は驚くべきものである。なお、本
発明の好ましい実施形態は、後述するように連続方式で
ある。The inventor of the present invention has made the raw material PE of the conventional depolymerization method.
To fully remove the instability factor due to T, the raw material PET
Can be melted at a high temperature to remove low-boiling compounds (water, hydrochloric acid, etc.), while on the other hand, in order to obtain a reaction process with high productivity (rate and stability) while suppressing side reactions, We found that depolymerization should be carried out as a homogeneous solution reaction at the lowest temperature possible, and as a result of diligent studies on a method that can realize both requirements, we found that the molten and degassed polymer in the molten state was treated with a catalyst and a small amount of ethylene glycol. The present inventors have completed the present invention by discovering that an oligomer soluble in ethylene glycol at a temperature of 250 ° C. or less should be rapidly reacted. The quality and productivity improving effects obtained by the method of the present invention are surprising. The preferred embodiment of the present invention is a continuous system, as will be described later.

【００１０】[0010]

【発明の実施の形態】本発明の対象とする、再利用に供
されるＰＥＴは、如何なる原料から如何なる方法によっ
て製造されたものであってもよい。例えば、テレフター
ル酸またはジメチルテレフタレートとエチレングリコー
ル、あるいはテレフタール酸とエチレンオキサイドを原
料として、ＢＨＥＴまたは／およびそのオリゴマーを経
て常法により重合したものが用いられる。ＰＥＴの用途
に応じて、これらに少量の第三成分あるいは添加剤を加
えて製造したものもほぼ同様に利用できる。また、重合
方法として、溶融重合、およびそれに加えて高重合度品
を得るための固相重合を行って製造したものであっても
よい。BEST MODE FOR CARRYING OUT THE INVENTION The PET to be recycled, which is the object of the present invention, may be produced from any raw material by any method. For example, terephthalic acid or dimethyl terephthalate and ethylene glycol, or terephthalic acid and ethylene oxide are used as raw materials and polymerized by a conventional method through BHET or / and its oligomer. Depending on the intended use of PET, those produced by adding a small amount of the third component or additive to these may be used in substantially the same manner. Further, the polymerization method may be a method produced by melt polymerization and, in addition thereto, solid phase polymerization for obtaining a high degree of polymerization product.

【００１１】実際に再利用に供されるＰＥＴは、通常、
成形品とするために溶融紡糸・成膜・成形、延伸、熱処
理などの工程を経たものである。従って、少なくとも部
分的に高配向・高結晶化したものが多い。なお、これら
のＰＥＴおよびＰＥＴ成形品製造工程で発生した規格外
の中間品、あるいは製品なども利用できる。成形品を主
とするこれらのＰＥＴは、再利用に当って必要に応じ
て、破砕、切断、比重選別、洗浄（水、エチレングリコ
ールなどによる）等の前処理を経て解重合工程に供され
る。なお、解重合に供されるＰＥＴに少量の水、異種ポ
リマーなどが混在することは実際上避けられず、それら
を前処理工程で完全に取り除くことは困難である。ま
た、混在量は不規則に大きく変動する。The PET that is actually used for reuse is usually
It has undergone steps such as melt spinning, film formation, molding, stretching, and heat treatment in order to obtain a molded product. Therefore, many of them are at least partially highly oriented and highly crystallized. It should be noted that non-standard intermediate products or products generated in these PET and PET molded product manufacturing processes can also be used. These PETs, which are mainly molded products, are subjected to pretreatments such as crushing, cutting, specific gravity selection, washing (with water, ethylene glycol, etc.), etc., as required for reuse, and then subjected to the depolymerization step. . In addition, it is unavoidable that a small amount of water, a different polymer, and the like are mixed in the PET used for depolymerization, and it is difficult to completely remove them in the pretreatment step. Further, the mixed amount fluctuates irregularly and greatly.

【００１２】本発明においては、従来の通常の解重合反
応方法を不安定にする水、異種ポリマーの混在するＰＥ
Ｔおよび／あるいはＰＥＴ固体の外部形状および内部性
状に大きな斑のあるＰＥＴを対象とすることができる。
本発明の対象とするＰＥＴをより具体的に示せば、成形
品としては、狭義には清涼飲料、酒類、調味料などの透
明容器として用いられた、いわゆるＰＥＴボトルの回収
品が最も代表的である。エンジニアリングプラスチック
として、機械、電気・電子部品などに用いられたものも
含まれる。成膜品としては、フィルムあるいはシート状
に成形し、そのまま写真フィルム、各種テープ、防護膜
などに、あるいは用途に応じてさらに透明包装容器など
に賦形して用いられたものがある。無論、大量用途であ
る繊維および各種繊維製品として紡糸・成形されたもの
も対象とすることができる。In the present invention, PE in which water and a heterogeneous polymer are mixed, which makes the conventional ordinary depolymerization reaction method unstable.
PET having large irregularities in the external shape and internal properties of T and / or PET solids can be targeted.
More specifically, the target PET of the present invention is, as the molded product, a so-called PET bottle recovered product, which is used in a narrow sense as a transparent container for soft drinks, alcoholic beverages, seasonings and the like, is the most representative. is there. Engineering plastics include those used for machinery, electrical and electronic parts, etc. As the film-formed product, there is a film or sheet-shaped product which is used as it is as a photographic film, various tapes, a protective film or the like, or further shaped into a transparent packaging container or the like depending on the application. As a matter of course, fibers that are mass-produced and various fiber products that are spun and molded can also be targeted.

【００１３】最も代表的な成形品であるボトル類につい
て付け加えると、それは消費者、飲料販売会社、回収業
者、市町村などの自治体の協力の下に分別回収され、圧
縮したベールとして再生プラントヘ搬入される。解砕
し、混入している金属、紙などとともに、異種ポリマ
ー、とりわけポリ塩化ビニールを選別分離しようとする
が、手作業を以ってしても完全に選別することは難し
い。特にラベル等の形でボトル本体に密着しているもの
は、機械的に分離する方法が有効だが、不十分となりや
すい。本発明では、前処理工程での十分な分離が実際上
できない、原料ＰＥＴに含まれる異種ポリマーを解重合
反応工程で分離しやすくし、ポリ塩化ビニールから発生
する塩酸を解重合反応以前に分離するために、また、吸
着および洗浄処理などで付着残留した水を除去するため
に、そしてＰＥＴ固体の反応性の斑をなくすために、解
重合反応工程に供給されるＰＥＴを、先ず高温度で溶融
し、脱ガスする。In addition to the bottles, which are the most representative molded products, they are separated and collected in cooperation with local governments such as consumers, beverage sales companies, collectors, municipalities, etc., and are delivered to the recycling plant as compressed bales. . It is attempted to separate and dissociate dissimilar polymers, especially polyvinyl chloride, along with crushed and mixed metals and paper, but it is difficult to completely separate them even by manual work. Especially for those that are in close contact with the bottle body in the form of a label or the like, the mechanical separation method is effective, but it tends to be insufficient. In the present invention, different polymers contained in the raw material PET, which cannot be sufficiently separated in the pretreatment step, are easily separated in the depolymerization reaction step, and hydrochloric acid generated from polyvinyl chloride is separated before the depolymerization reaction. In order to remove residual water adhering to the depolymerization reaction step, such as adsorption and washing treatment, and to eliminate the reactivity unevenness of the PET solid, the PET fed to the depolymerization reaction step is first melted at a high temperature. And degas.

【００１４】その温度はＰＥＴの重合度、結晶化度、共
重合成分、形状などで変わるが、好ましくは２６０乃至
３００℃の範囲が用いられる。その溶融方法としては、
ＰＥＴを脱ガス孔を設けた溶融押出機に送入して短時間
に行うのが好ましい。ＰＥＴがかさ高な繊維状である場
合などは、加熱壁を持つホッパー型の設備を用いてもよ
いが、定量性などの操業安定性を確保するためには押出
機を併用するのが望ましい。溶融中に発生した水、塩酸
などの低沸点物は、脱ガス孔などから吸収装置に導き、
アルカリ性水溶液と接触させて捕捉する。溶融ＰＥＴは
貯槽に送り、短時間滞留させて未分解のポリ塩化ビニー
ルの脱塩酸を完了させるのが好ましい。ＰＥＴに混入し
ていたポリ塩化ビニールは、通常、溶融温度で数分乃至
１０分以内に分解脱塩酸を終了する。The temperature varies depending on the degree of polymerization of PET, the degree of crystallinity, the copolymerization component, the shape, etc., but is preferably in the range of 260 to 300 ° C. As the melting method,
It is preferable to feed PET into a melt extruder provided with degassing holes and to carry out it in a short time. When PET is a bulky fibrous material, a hopper type equipment having a heating wall may be used, but it is desirable to use an extruder together in order to ensure operational stability such as quantitativeness. Water, low boiling point substances such as hydrochloric acid generated during melting are led to the absorber through degassing holes,
Capture by contacting with an alkaline aqueous solution. The molten PET is preferably sent to a storage tank and retained for a short time to complete the dehydrochlorination of undecomposed polyvinyl chloride. The polyvinyl chloride mixed in PET usually completes the decomposition and dehydrochlorination within a few minutes to 10 minutes at the melting temperature.

【００１５】脱水、脱塩酸、脱低沸点物された溶融ＰＥ
Ｔは、好ましくはフィルターを経由したのち、予備解重
合反応器に送り、解重合触媒および予熱したエチレング
リコールと混合し、短時間反応させる。反応時間は温度
および触媒とエチレングリコールの量によって変わる
が、好ましくは１０分以内、長くとも２０分以内とする
のが望ましい。反応温度は溶融温度を維持してもよい
が、溶融湿度の高い場合でも、例えば２６０乃至２８０
℃で十分である。解重合触媒としては、例えば、アルカ
リ金属の水酸化物、アルコレート、炭酸塩、カルボン酸
塩等が用いられる。解重合触媒は、原料ＰＥＴに対し、
好ましくは０.０５乃至１重量％で用いられる。これは
一例であり、種類、量ともこれらに限定されない。即
ち、耐熱性があり、ＰＥＴとＢＨＥＴの品質を悪化させ
ないエステル交換触媒能のある化合物であれば、大部分
それぞれの性能に応じて使用可能である。解重合触媒
は、２種類以上を併用してもよい。Molten PE dewatered, dehydrochlorinated, deboiling
T is preferably passed through a filter, then sent to a pre-depolymerization reactor, mixed with a depolymerization catalyst and preheated ethylene glycol, and reacted for a short time. The reaction time varies depending on the temperature and the amount of the catalyst and ethylene glycol, but it is preferably within 10 minutes, and at most within 20 minutes. The reaction temperature may be maintained at the melting temperature, but even when the melting humidity is high, for example, 260 to 280.
° C is sufficient. As the depolymerization catalyst, for example, an alkali metal hydroxide, alcoholate, carbonate, carboxylate or the like is used. The depolymerization catalyst is
It is preferably used in an amount of 0.05 to 1% by weight. This is an example, and the type and amount are not limited to these. That is, as long as it is a compound having heat resistance and a transesterification catalytic ability that does not deteriorate the quality of PET and BHET, most of them can be used according to their respective performances. Two or more kinds of depolymerization catalysts may be used in combination.

【００１６】解重合触媒の代表的なものとして、例えば
水酸化ナトリウム、水酸化カリウム、ナトリウムメチラ
ート、マグネシウムメチラート、炭酸ナトリウム、酢酸
ナトリウム等を挙げることができる。エチレングリコー
ルの使用量は、原料ＰＥＴに対して１５乃至５０重量％
とする。少なすぎると生成した低重合体組成物（予備解
重合オリゴマー）は、解重合完結反応で用いるエチレン
グリコールヘの溶解性が不足する。多すぎてはＤＥＧお
よびＤＥＧＥＳＴＥＲの生成などの副反応が増え、反応
時圧力が上昇して反応器の耐圧を大きくしなければなら
ない不利も生ずる。エチレングリコールは含水量の少な
いものを用いるのが好ましい。Representative examples of the depolymerization catalyst include sodium hydroxide, potassium hydroxide, sodium methylate, magnesium methylate, sodium carbonate, sodium acetate and the like. The amount of ethylene glycol used is 15 to 50% by weight based on the raw material PET.
And If the amount is too small, the resulting low polymer composition (preliminary depolymerization oligomer) has insufficient solubility in ethylene glycol used in the depolymerization completion reaction. If it is too large, side reactions such as generation of DEG and DEGESTER increase, and the pressure during the reaction rises, which causes a disadvantage that the pressure resistance of the reactor must be increased. It is preferable to use ethylene glycol having a low water content.

【００１７】また、予備解重合には、エチレングリコ一
ルとともに、場合によりＢＨＥＴおよび／またはオリゴ
マーを併用することもできる。その場合、それらを含め
て所定のＰＥＴとエチレングリコールの比率を維持する
のが好ましい。ただし、ＢＨＥＴとオリゴマーは、エチ
レンテレフタレート単位とエチレングリコールから成る
ものとし、それぞれをＰＥＴとエチレングリコールの使
用量に加える。なお、ＢＨＥＴを多量に用いるとＤＥＧ
生成を促してしまう恐れがあり、４０重量％までとする
のがよい。ＢＨＥＴはプロセス内でその精製工程などか
らリサイクルされるものを用いるのが実際的である。通
常それはオリゴマーを含んでいる。In addition, BHET and / or an oligomer may be optionally used in combination with ethylene glycol for the preliminary depolymerization. In that case, it is preferable to maintain a predetermined ratio of PET and ethylene glycol including them. However, the BHET and the oligomer are composed of ethylene terephthalate units and ethylene glycol, and each is added to the amounts of PET and ethylene glycol used. In addition, if BHET is used in a large amount,
There is a risk of promoting the production, and it is preferable to set it to 40% by weight. It is practical to use BHET that is recycled from the purification step in the process. Usually it contains oligomers.

【００１８】予備解重合反応の好ましい操作方式は、連
続式である。例えば、反応器を攪拌式完全混合槽とし、
予備解重合の進んだ反応液へ溶融ＰＥＴとエチレングリ
コールおよび触媒を送入しつつ、他端から生成した低重
合体組成物を抜き出す方法がある。溶融ＰＥＴとエチレ
ングリコールは反応液に対して相溶性が高いので、容易
に均一化し、予備解重合は短時間で終了する。この場
合、エチレングリコールには予め触媒を溶解し、攪拌さ
れている反応液中に送入するのが好ましい。連続式完全
混合槽は１段でも、２段以上の多段でもよいが、好まし
くは３段以内とする。なお、反応器には低沸点化合物の
留去口を設けるのが好ましい。The preferred operation mode of the preliminary depolymerization reaction is a continuous mode. For example, the reactor is a stirring type complete mixing tank,
There is a method in which molten PET, ethylene glycol, and a catalyst are fed into a reaction solution in which preliminary depolymerization has proceeded, while the low polymer composition produced from the other end is withdrawn. Since melted PET and ethylene glycol have high compatibility with the reaction solution, they are easily homogenized, and the preliminary depolymerization is completed in a short time. In this case, it is preferable to dissolve the catalyst in ethylene glycol in advance and feed it into the stirred reaction solution. The continuous complete mixing tank may have one stage or multiple stages of two or more stages, but preferably within three stages. The reactor is preferably provided with a distillation port for the low boiling point compound.

【００１９】連続反応器としては、完全混合槽に限ら
ず、より押し出し流れに近い攪拌混合性能に優れた装置
も使用できる。例えば、スクリューフィーダー型のも
の、スタティックミキサー型のものなどが挙げられる。
予備解重合で生成した低重合体組成物は、フィルターな
どによって混在する異種ポリマー（ポリ塩化ビニールは
分解してポリエンとなっている）の凝集塊を分離したの
ち、解重合完結反応器に送られる。凝集塊の少ない場合
などは、ここでの分離操作を省略し、完結反応の途中お
よび／あるいは終了後に行ってもよい。The continuous reactor is not limited to the complete mixing tank, and an apparatus having a stirring and mixing performance closer to an extrusion flow can be used. Examples thereof include a screw feeder type and a static mixer type.
The low-polymer composition produced by pre-depolymerization is sent to the depolymerization completed reactor after separating the coagulated aggregates of different polymers (polyvinyl chloride is decomposed into polyene) by a filter. . When there are few aggregates, the separation operation here may be omitted and the reaction may be performed during and / or after the completion reaction.

【００２０】解重合完結反応はＰＥＴの２乃至１０重量
倍のエチレングリコールに低重量体組成物を溶解して行
う。だだし、ここでいうＰＥＴとエチレングリコールの
重量比は、完結反応器に供給された原料中の全エチレン
テレフタレート単位と全エチレングリコール（エチレン
テレフタレート単位を構成しているエチレングリコール
成分は除く）の倍率のことである。低重合体組成物を溶
解して均一溶液とし、ＰＥＴのほぼ８５重量％以上をＢ
ＨＥＴへ転化するには２重量倍以上が必要であるが、１
０重量倍を越えて用いてもＢＨＥＴの収率は実際上変わ
らず、反応器の生産性が低下する。好ましいエチレング
リコール使用量は、ＢＨＥＴへの転化率約９０重量％以
上が可能で生産性の高い、３乃至８重量倍である。The depolymerization completion reaction is carried out by dissolving the low-weight composition in 2 to 10 times the weight of PET by ethylene glycol. However, the weight ratio of PET and ethylene glycol referred to here is the ratio of all ethylene terephthalate units and all ethylene glycol (excluding the ethylene glycol component constituting the ethylene terephthalate unit) in the raw material supplied to the complete reactor. That is. Dissolve the low-polymer composition into a uniform solution, containing approximately 85% by weight or more of PET in B
More than 2 times by weight is required to convert to HET, but 1
The yield of BHET is practically unchanged even if it is used in excess of 0 times by weight, and the productivity of the reactor is lowered. The preferred amount of ethylene glycol used is 3 to 8 times by weight, which is highly productive with a conversion rate to BHET of about 90% by weight or more.

【００２１】完結反応の温度は、１８０乃至２５０℃と
する。１８０℃より低温では生産性が低く、副反応も少
なくならず、均一溶液反応の利点を生かせない。２５０
℃を越えると副反応が大きくなり、反応器の耐圧性も大
きくしなければならない。均一溶液反応の安定性、反応
速度大、副反応小という特長を生かした、設備的にも有
利な好ましい温度範囲は、エチレングリコールの常圧下
沸点近傍の１９０乃至２４０℃である。反応温度は一定
でなくともよい。完結反応の時間は、温度、触媒、エチ
レングリコールの量などで変わるが、数分乃至数時間で
ある。実際的には反応操作を安定させやすく、生産性の
高い、副反応を少なくできる１０分乃至１時間とする。
均一溶液系の反応時間は、同条件のＰＥＴ固体片を反応
させる不均一系にくらべ、数分の１から２分の１で十分
である。The temperature of the completion reaction is 180 to 250 ° C. When the temperature is lower than 180 ° C, the productivity is low, side reactions do not decrease, and the advantages of homogeneous solution reaction cannot be utilized. 250
If the temperature exceeds ° C, side reactions will increase and the pressure resistance of the reactor must also be increased. A preferable temperature range, which is advantageous in terms of equipment and which takes advantage of the stability of a homogeneous solution reaction, a large reaction rate, and a small side reaction, is 190 to 240 ° C., which is near the boiling point of ethylene glycol under normal pressure. The reaction temperature does not have to be constant. The time of the completion reaction varies depending on the temperature, the catalyst, the amount of ethylene glycol and the like, but is several minutes to several hours. Practically, the reaction time is set to 10 minutes to 1 hour, which makes it easy to stabilize the reaction operation, has high productivity, and can reduce side reactions.
The reaction time of the homogeneous solution system is several times to one half that of the heterogeneous system in which PET solid pieces are reacted under the same conditions.

【００２２】完結反応の好ましい操作方式も連続式であ
る。均一溶液系であることによって反応器形式の選択の
幅は広くできる。反応時間を最小とし、副反応の割合を
少なくするためには、押出し流れに近いものが好ましい
が、攪拌槽を縦あるいは横に連結した多段混合槽も用い
られる。ここでも低沸点物の留出口を設け、熱分解生成
物、水などを留去する。反応器の入り口で低重合体組成
物を、予熱したエチレングリコールに溶解し、所定の反
応温度とするが、場合により精製工程などからリサイク
ルされたＢＨＥＴおよび／またはオリゴマーをここで添
加することもできる。解重合反応が完結した反応液は、
ほぼ反応平衡に達しているが、ＤＥＧおよびＤＥＧＥＳ
ＴＥＲの副生する反応は続いている。できるだけ早く冷
却してこれを実際上停止したのち、生成したＢＨＥＴを
分離、精製する。分離精製工程には公知の方法を用いる
ことができる。本発明者がすでに提案した方法、例えば
脱イオン、脱色、濃縮、蒸留、晶析などの一部または全
部を組み合わせた方法を用いることは有用である。The preferred operation mode for the completion reaction is also a continuous mode. The homogeneous solution system allows a wide range of choices for the reactor type. In order to minimize the reaction time and reduce the proportion of side reactions, it is preferable that the flow is close to the extrusion flow, but a multi-stage mixing tank in which stirring tanks are connected vertically or horizontally is also used. In this case as well, a distillation outlet for a low boiling point substance is provided to distill off thermal decomposition products, water and the like. At the inlet of the reactor, the low polymer composition is dissolved in preheated ethylene glycol to a predetermined reaction temperature, but BHET and / or oligomer recycled from the purification step or the like may be added here if necessary. . The reaction liquid in which the depolymerization reaction is completed is
Almost reaction equilibrium is reached, but DEG and DEGES
The reaction of by-product of TER continues. After cooling as soon as possible and stopping this practically, the produced BHET is separated and purified. A known method can be used for the separation and purification step. It is useful to use the method already proposed by the present inventors, for example, a method combining a part or all of deionization, decolorization, concentration, distillation, crystallization and the like.

【００２３】なお、反応液に顔料などの微小固形物が含
まれているときは、冷却の前または後で、固形物の性状
と量に応じた濾別方法を用いてこれを分離することがで
きる。本発明者がすでに提案した関連する分離精製方法
としては、特開２００１−４８８３７号公報（脱イオン
法）、特開２００１−４８８３５号公報（蒸留法）、特
開２００１−４８８３６号公報（蒸留法）、および特願
平１２−２３８０６１（晶析法）などがある。これらを
活用した分離精製工程の例を連続方式として以下に示す
が、無論、回分式でも実施できる。１００℃以下まで冷
却した反応液は、活性炭塔に通して脱色した後、イオン
交換塔で脱カチオン、脱アニオン処理する。脱イオンは
ＰＥＴ中の重合触媒、エステル交換触媒、および解重合
触媒に由来するイオンを分離するだけでなく、各種汚染
物に由来する金属イオン、非金属の無機イオン、および
有機イオンを分離し、以後の工程を安定させて効率を高
めるとともに、ＢＨＥＴの品質を大幅に改善する。When the reaction liquid contains a fine solid such as a pigment, it may be separated before or after cooling by a filtering method according to the property and amount of the solid. it can. As related separation and purification methods already proposed by the present inventor, there are JP-A-2001-48837 (deionization method), JP-A-2001-48835 (distillation method), and JP-A-2001-48836 (distillation method). ), And Japanese Patent Application No. 12-238061 (crystallization method). An example of a separation and purification process utilizing these is shown below as a continuous system, but it goes without saying that a batch system can also be used. The reaction liquid cooled to 100 ° C. or lower is passed through an activated carbon tower for decolorization, and then subjected to decationization and deanion treatment in an ion exchange tower. Deionization not only separates ions derived from the polymerization catalyst, transesterification catalyst, and depolymerization catalyst in PET, but also separates metal ions, non-metal inorganic ions, and organic ions derived from various contaminants, It stabilizes the subsequent steps to improve efficiency and greatly improves the quality of BHET.

【００２４】脱色、脱イオンとも有機溶媒系の処理であ
るが、エチレングリコールの極性は高いため、温度以外
は水系の通常のイオン交換処理条件に近い条件、例えば
処理時間の指標である空間速度は４ｈｒ-1前後で処理可
能である。温度は反応液中のＢＨＥＴ濃度などによって
も変わるが、通常は６０℃以上、好ましくは７０℃以上
とする。処理後のイオン濃度は、ＢＨＥＴおよびオリゴ
マーに対して好ましくは５０ｐｐｍ以下、より好ましく
は３０ｐｐｍ以下とする。脱イオンを終了した反応液
は、連続晶析機で常温付近（約２０℃）、あるいは常温
以下まで冷却して、ＢＨＥＴ（オリゴマーを含む）を析
出させる。平均晶析時間は２乃至１０時間とする。析出
結晶は、例えば遠心分離法、真空濾過法、フィルタープ
レス法（加圧濾過法）などによって溶媒を分離し、必要
に応じて少量のエチレングリコールで洗浄後溶融し、真
空下に薄膜蒸留機などを用いる急速蒸発を行って、残留
溶媒（エチレングリコール、ＤＥＧなど）をほぼ完全に
留去する。Both decolorization and deionization are organic solvent-based treatments, but since ethylene glycol has a high polarity, conditions other than temperature are close to those of ordinary water-based ion exchange treatment conditions, for example, space velocity, which is an index of treatment time, is It can be processed at around 4 hr -1 . Although the temperature varies depending on the BHET concentration in the reaction solution and the like, it is usually 60 ° C or higher, preferably 70 ° C or higher. The ion concentration after the treatment is preferably 50 ppm or less, more preferably 30 ppm or less with respect to BHET and the oligomer. The deionized reaction solution is cooled to around room temperature (about 20 ° C.) or below room temperature by a continuous crystallizer to precipitate BHET (including oligomer). The average crystallization time is 2 to 10 hours. Precipitated crystals are separated from the solvent by, for example, centrifugation, vacuum filtration, filter press (pressure filtration), washed with a small amount of ethylene glycol if necessary, and then melted. Is used to drive off the residual solvents (ethylene glycol, DEG, etc.) almost completely.

【００２５】次いで、通常２００Ｐａ（１.５ｍｍＨ
ｇ）以下の高真空下にＢＨＥＴを薄膜蒸留機で急速蒸留
して精製ＢＨＥＴを取得する。蒸留機内のＢＨＥＴ滞留
時間は、溶媒留去の場合も、ＢＨＥＴ蒸留の場合も数分
以内、通常２分以内である。ここで発生する蒸留残はオ
リゴマ−および高沸点不純物（着色物質なども含む）濃
度が高くなったＢＨＥＴであり、一部をプロセス外へ排
出するが、大部分は解重合反応工程へリサイクルされ
る。なお、原料ＰＥＴの汚染が少ない場合は、晶析・濾
過・洗浄を行った後、ＢＨＥＴを蒸留することなく重縮
合工程に供給することも可能である。また、エチレング
リコールを留去後、フレーク化（フレーカーによる冷却
固化）することもできる。Then, normally 200 Pa (1.5 mmH
g) Purify BHET by rapidly distilling BHET with a thin film distiller under the following high vacuum. The BHET residence time in the distiller is within a few minutes, usually within 2 minutes for both solvent distillation and BHET distillation. The distillation residue generated here is BHET with a high concentration of oligomers and high-boiling-point impurities (including coloring substances), and a part of it is discharged out of the process, but most of it is recycled to the depolymerization reaction step. . When the raw material PET is less contaminated, BHET can be supplied to the polycondensation step without distillation after crystallization, filtration and washing. Further, after distilling off ethylene glycol, it is also possible to make into flakes (cooling and solidification with a flaker).

【００２６】精製ＢＨＥＴは、溶融状態のまま、あるい
はフレーク化した後、ＰＥＴ重合工程に送り、溶融ある
いはさらに固相重合を行って用途に応じた性状を持つＰ
ＥＴとする。その場合、高純度のテレフタール酸と混合
使用することもできる。イソフタール酸などの共重合成
分の使用も問題なく可能である。本発明方法を利用して
得られる精製ＢＨＥＴによって、繊維、フィルム、シー
トからボトルまで広範な用途の、各種スペックを満足す
る高品質ＰＥＴを製造できる。なお、解重合原料ＰＥＴ
の品質が比較的良好な場合には、晶析分離したＢＨＥＴ
を蒸留することなくＰＥＴ製造に供することも可能であ
るが、晶析工程に替えて、脱イオン後の反応液を急速蒸
発方法で濃縮してエチレングリコールを分離し、次いで
蒸留精製を行って精製ＢＨＥＴを得ることも可能であ
る。Purified BHET is sent to the PET polymerization step in the molten state or after being made into flakes, and then melted or further solid-phase polymerized to obtain P having properties suitable for the intended use.
Let's say ET. In that case, it can also be used as a mixture with high-purity terephthalic acid. The use of a copolymerization component such as isophthalic acid is also possible without problems. Purified BHET obtained by using the method of the present invention can produce high-quality PET satisfying various specifications for a wide range of applications from fibers, films, sheets to bottles. Depolymerization raw material PET
If the quality of BHET is relatively good
It is also possible to use it for PET production without distilling, but in place of the crystallization step, the reaction liquid after deionization is concentrated by the rapid evaporation method to separate ethylene glycol, and then purified by distillation. It is also possible to get BHET.

【００２７】本発明方法による生産性、品質、収率の向
上は驚くべきものである。即ち、解重合反応工程だけを
とっても、生産性の一つの指標である反応器の空時収率
は、従来のＰＥＴ固体片を反応させる方法に較べて、少
なくとも２倍、通常３倍以上とすることができる。従来
法の不安定性を考慮した操作を基準とすれば、数倍以上
となる。操業安定性を評価に加えれば、本発明方法のメ
リットは計り知れない。連続化による操作の安定化、無
益な滞留時間が少なくなる利点も大きい。滞留時間減
少、操業安定性の向上などは、滞留時間に比例的な副反
応を著しく少なくする。即ち、解重合反応工程でのＤＥ
ＧとＤＥＧＥＳＴＥＲの増大は、２分の１乃至数分の１
となる。また、ＭＨＥＴも少なくなる。The improvement of productivity, quality and yield by the method of the present invention is surprising. That is, even if only the depolymerization reaction step is performed, the space-time yield of the reactor, which is one index of productivity, is at least twice, usually three times or more, as compared with the conventional method of reacting PET solid pieces. be able to. Based on the operation considering the instability of the conventional method, it is several times or more. If the operation stability is added to the evaluation, the merit of the method of the present invention is immeasurable. There are great advantages that the operation is stabilized by continuous operation and the useless residence time is reduced. Reducing the residence time and improving operational stability significantly reduce side reactions proportional to the residence time. That is, DE in the depolymerization reaction step
G and DEGESTER increase by a factor of 2 to 1
Becomes Also, MHET is reduced.

【００２８】ＤＥＧとＤＥＧＥＳＴＥＲの減少は、解重
合反応後の晶析操作を容易にし、ＢＨＥＴの晶析収率を
改善し、ＢＨＥＴ結晶中のＤＥＧＥＳＴＥＲなどの不純
物含有率を著しく少なくする。また、単蒸留に近い急速
蒸留操作を行う蒸留精製工程でのＤＥＧＥＳＴＥＲの分
離は、蒸留率を高くすると不十分になりやすいが、蒸留
前のＢＨＥＴ結晶中のＤＥＧＥＳＴＥＲ減少により、精
製ＢＨＥＴ中のＤＥＧＥＳＴＥＲ含有率を低く保って蒸
留収率を高くすることできる。主原料のＰＥＴおよびエ
チレングリコールの原単位は、副反応、副生成物の減
少、各工程の効率と収率の向上によって大幅に改善され
る。また、ポリ塩化ビニールなどから発生する塩酸は、
原料ＰＥＴの溶融工程で除去されるため、解重合触媒と
結合した塩化物は、ほとんど生成しない。そのため触媒
を多めに使う必要がなく、脱イオン塔の負荷は小さく、
安定したものとなる。The reduction of DEG and DEGESTER facilitates the crystallization operation after the depolymerization reaction, improves the crystallization yield of BHET, and significantly reduces the content of impurities such as DEGESTER in BHET crystals. Also, the separation of DEGESTER in the distillation purification step, which is a rapid distillation operation similar to simple distillation, tends to be insufficient when the distillation rate is increased, but due to the decrease in DEGESTER in the BHET crystals before distillation, the DEGESTER content in the purified BHET is reduced. The rate can be kept low to increase the distillation yield. The basic units of PET and ethylene glycol, which are the main raw materials, are significantly improved by side reactions, reduction of by-products, and improvement in efficiency and yield of each step. Also, hydrochloric acid generated from polyvinyl chloride, etc.
Since the raw material PET is removed in the melting step, almost no chloride is bound to the depolymerization catalyst. Therefore, it is not necessary to use a large amount of catalyst, the load on the deionization column is small,
It will be stable.

【００２９】[0029]

【実施例】以下に実施例を示して、本発明の具体的な態
様と特徴、利点について説明する。無論、本発明はこれ
らに限定されるものではない。EXAMPLES Specific examples, features, and advantages of the present invention will be described below with reference to examples. Of course, the present invention is not limited to these.

【００３０】実施例１ （１） 使用済みＰＥＴボトルの洗浄粉砕フレークを２
３.０ｋｇ／ｈｒ速度で、スクリュー径５０ｍｍを備え
た単軸押出機に送入した。溶融温度は２９０℃とし、低
沸点物を脱ガス孔から除きながら溶融ポリマーを押し出
し、貯槽に５分間滞留させて混入ポリ塩化ビニール（平
均約０.５ｗｔ％、発生塩酸量から推算）の熱分解を完
了させた。 （２） 脱塩酸終了後の溶融ＰＥＴを、直ちに攪拌機つ
き予備解重合反応器に送り、既に予備解重合済みの２７
０℃の反応液（低重合体組成物）と混合した。一方予熱
して所定量（解重合反応の全エチレンテレフタレート単
位に対して０.２ｗｔ％）の水酸化ナトリウムを溶解し
た、原料ＰＥＴに対して３０ｗｔ％（６.９ｋｇ／ｈ
ｒ）のエチレングリコールを反応液中に注入した。予備
解重合反応の温度は２７０℃、反応液の反応器滞留時間
は４分とし、反応中に少量の低沸点物を留去した。器底
から取り出された反応液は均一溶液で、僅かなポリオレ
フィン（平均約１ｗｔ％）と、ポリ塩化ビニールが分解
して生成した褐色のポリエンが混在していた。反応液は
フィルターによってポリオレフィンとポリエンの凝集塊
などを取り除いた後、解重合完結反応器に送入した。Example 1 (1) Washed crushed flakes of used PET bottles were added to 2 pieces.
It was fed into a single-screw extruder equipped with a screw diameter of 50 mm at a speed of 3.0 kg / hr. The melting temperature was 290 ° C, the molten polymer was extruded while removing low-boiling substances from the degassing holes, and allowed to stay in the storage tank for 5 minutes to thermally decompose the mixed polyvinyl chloride (average 0.5 wt%, estimated from the amount of generated hydrochloric acid). Was completed. (2) The molten PET after the completion of dehydrochlorination was immediately sent to a predepolymerization reactor equipped with a stirrer, and the predepolymerized 27
It was mixed with a reaction liquid (low polymer composition) at 0 ° C. On the other hand, preheated to dissolve a predetermined amount (0.2 wt% of all ethylene terephthalate units of depolymerization reaction) of sodium hydroxide, 30 wt% (6.9 kg / h) of the raw material PET.
Ethylene glycol of r) was injected into the reaction solution. The temperature of the preliminary depolymerization reaction was 270 ° C., the residence time of the reaction solution in the reactor was 4 minutes, and a small amount of low-boiling substances was distilled off during the reaction. The reaction solution taken out from the bottom of the vessel was a homogeneous solution, and a small amount of polyolefin (on average about 1 wt%) and brown polyene produced by decomposition of polyvinyl chloride were mixed. After removing the aggregates of polyolefin and polyene from the reaction solution by a filter, the reaction solution was fed into a depolymerization completed reactor.

【００３１】（３） 完結反応器には、４つの同容積の
完全混合槽をつないだ形のものを用い、その第１槽に予
備重合反応液、ＢＨＥＴ蒸留精製工程から回収した蒸留
残液（ダイマーとＢＨＥＴが主成分）、晶析・濾過工程
から回収した濾液とその一部を蒸留精製して得たエチレ
ングリコール、ＢＨＥＴ蒸留の前工程である残留溶媒留
去工程から回収したエチレングリコール、および新しい
原料エチレングリコールを送入した。ただし、それらの
全エチレンテレフタレート単位に対して全エチレングリ
コールが５.０重量倍となるように調整した。各槽の温
度と反応液滞留時間は２２０℃、５分とした。 （４） 第４槽から取り出されフィルターを経た反応液
は、原料ＰＥＴフレーク中の着色剤、汚染物などにより
淡褐色となっていたが、透明な均一溶液であった。これ
を急冷して８０℃とした後、平均粒径約１ｍｍの粒状活
性炭を充填した脱色塔に通した。次いでカチオン交換樹
脂塔とアニオン交換樹脂塔に通して解重合触媒のナトリ
ウムイオンを含む各種イオンを吸着除去した。通液速度
は、活性炭塔については空間速度２ｈｒ-1、イオン交換
塔は４ｈｒ-1とした。脱イオン後の反応液を連続晶析器
へ送り、１０℃まで冷却してＢＨＥＴを析出させ、器底
から結晶と母液を取り出した。晶析器平均滞留時間は４
時間とした。結晶と母液はフィルタープレスによって半
連続的に分離し、含液率約４０ｗｔ％のケークを得た。
これをエチレングリコールで洗浄後、９０℃まで加熱し
て溶融し、薄膜蒸留器に送ってエチレングリコ一ル、Ｄ
ＥＧなどの低沸点物を真空下、１５０℃で連続的に急速
留去した。晶析・溶媒分離工程の（粗）ＢＨＥＴ収率は
８５ｗｔ％であった。低沸点物を除かれた溶融状態のＢ
ＨＥＴは、つづいて高真空操作が行える薄膜蒸留器（い
わゆる分子蒸留器）に送り、２４Ｐａ（０.１８ｍｍＨ
ｇ）、２００℃の条件で連続急速蒸留し、留出速度２
７.０ｋｇ／ｈｒで精製ＢＨＥＴを得た。精製ＢＨＥＴ
の蒸留工程収率は８０ｗｔ％、原料ＰＥＴに対する収率
は９１ｍｏ１％であった。精製ＢＨＥＴの品質分析値を
表１に示した。(3) As a complete reactor, one having four perfect mixing tanks of the same volume connected to each other was used, and in the first tank, a prepolymerization reaction solution and a distillation residual liquid (from the BHET distillation purification step) Dimer and BHET are the main components), the filtrate recovered from the crystallization / filtration step and ethylene glycol obtained by distilling and purifying a part of the filtrate, ethylene glycol recovered from the residual solvent distillation step which is the previous step of BHET distillation, and A new raw material ethylene glycol was introduced. However, the total ethylene glycol was adjusted to 5.0 times the total ethylene terephthalate unit. The temperature of each tank and the residence time of the reaction solution were 220 ° C. and 5 minutes. (4) The reaction solution taken out from the fourth tank and passed through the filter was a light brown color due to the colorant and contaminants in the raw material PET flakes, but it was a transparent homogeneous solution. This was rapidly cooled to 80 ° C., and then passed through a decolorization tower packed with granular activated carbon having an average particle size of about 1 mm. Then, various ions including sodium ions of the depolymerization catalyst were adsorbed and removed through a cation exchange resin tower and an anion exchange resin tower. Liquid permeation rate, space velocity 2 hr -1 for the activated carbon column, ion exchange column was 4hr -1. The reaction liquid after deionization was sent to a continuous crystallizer, cooled to 10 ° C. to precipitate BHET, and crystals and mother liquor were taken out from the bottom of the device. Crystallizer average residence time is 4
It was time. The crystals and mother liquor were semi-continuously separated by a filter press to obtain a cake having a liquid content of about 40 wt%.
This is washed with ethylene glycol, heated to 90 ° C to melt, and sent to a thin film distiller for ethylene glycol, D
Low boiling substances such as EG were rapidly distilled off continuously at 150 ° C. under vacuum. The (crude) BHET yield in the crystallization / solvent separation step was 85 wt%. B in the molten state from which low-boiling substances have been removed
HET is then sent to a thin film distiller (so-called molecular distiller) that can perform high vacuum operation, and 24 Pa (0.18 mmH)
g), continuous rapid distillation under the condition of 200 ° C, distillation rate 2
Purified BHET was obtained at 7.0 kg / hr. Purified BHET
The yield of the distillation step was 80 wt%, and the yield based on the raw material PET was 91 mol 1%. The quality analysis values of the purified BHET are shown in Table 1.

【００３２】（５） 溶融状態で取り出された精製ＢＨ
ＥＴは、大部分はフレーカーに送って冷却固化し、フレ
ークとして窒素雰囲気の貯槽に保存し、一部を溶融状態
のまま回分式重合器に送り、ＰＥＴを製造した。即ち、
６０ｋｇの精製ＢＨＥＴを攪拌機つきオートクレーブに
仕込み、窒素雰囲気下で予めエチレングリコールに溶解
した二酸化ゲルマニウムを、生成するＰＥＴに対して１
４０ｐｐｍ添加して重合を開始した。昇温して約２００
℃で生成するエチレングリコールを留去しながら、約４
０分間加熱してオリゴマーとした後、さらに徐々に昇温
して２８０℃、９０Ｐａ（０.７ｍｍＨｇ）の条件で約
２時間重縮合を行った。得られたＰＥＴの品質分析値も
表１に併記した。(5) Purified BH taken out in a molten state
Most of the ET was sent to a flaker to be cooled and solidified, stored as flakes in a nitrogen atmosphere storage tank, and part of the ET was sent to a batch type polymerizer in a molten state to produce PET. That is,
60 kg of purified BHET was charged into an autoclave equipped with a stirrer, and germanium dioxide preliminarily dissolved in ethylene glycol under a nitrogen atmosphere was added to the produced PET in an amount of 1
40 ppm was added to initiate polymerization. About 200
Approximately 4 while distilling off ethylene glycol produced at ℃
After heating for 0 minutes to form an oligomer, the temperature was gradually raised to carry out polycondensation under the conditions of 280 ° C. and 90 Pa (0.7 mmHg) for about 2 hours. The quality analysis values of the obtained PET are also shown in Table 1.

【００３３】比較例１ （１） 実施例１と同じ使用済みＰＥＴボトルの洗浄粉
砕フレーク６０ｋｇとエチレングリコール３００ｋｇを
攪拌機つきオートクレーブに仕込み、解重合触媒として
水酸化ナトリウム０.１２ｋｇを加えて、２２０℃で低
沸点物を留去しながら反応させたが、３０分後もほとん
ど反応は進んでないことがわかった。そこで、水酸化ナ
トリウム０.１８ｋｇを追加してさらに６０分反応さ
せ、ＰＥＴフレークを完全に溶解させた。 （２） これをフィルターで濾過しながら冷却槽に移し
て８０℃まで冷却し、以後の工程は、実施例１に準じる
方法で脱色、脱イオン、晶析・濾過、エチレングリコー
ルなどの留去、及びＢＨＥＴの蒸留を行った。ただし、
精製ＢＨＥＴの蒸留収率は７５ｗｔ％にとどめた。さら
に、実施例１に準じて晶析・濾過工程から回収した濾
液、及びその一部を蒸留精製して得たエチレングリコー
ル、残留溶媒留去工程から回収したエチレングリコール
ならびにＢＨＥＴ蒸留精製工程から回収した残液を新原
料に加えて再使用しながら、くりかえし回分式で解重合
反応を行った。解重合反応の全エチレンテレフタレート
単位に対する全エチレングリコールの重量比は第１バッ
チと同じ５.０倍、触媒の水酸化ナトリウムは０.２ｗｔ
％に調整した。その第５バッチの晶析濾過後のケーク含
液率は５２ｗｔ％、晶析・溶媒分離工程のＢＨＥＴ収率
は７９ｗｔ％であった。また、原料ＰＥＴに対する精製
ＢＨＥＴの収率は８０ｍｏｌ％であった。精製ＢＨＥＴ
の品質分析値を実施例１の結果とともに表１に示した。 （３） この精製ＢＨＥＴについて、実施例１とほぼ同
様の規模、操作により重縮合を行った。得られたＰＥＴ
の品質分析値を表１に併記した。なお、表中の光学密度
とは、ＢＨＥＴの１０ｗｔ％メタノール溶液の吸光度
を、波長３８０ｎｍ、セル長１０ｍｍにて測定した着色
物濃度に比例的な数値である。また、白度はＢＨＥＴに
ついては粉末、ＰＥＴについては結晶化固体表面を測定
したものである。Comparative Example 1 (1) 60 kg of the same washed PET flakes as used in Example 1 and 300 kg of ethylene glycol were placed in an autoclave equipped with a stirrer, 0.12 kg of sodium hydroxide was added as a depolymerization catalyst, and the temperature was set to 220 ° C. The reaction was carried out while distilling off the low-boiling substance, but it was found that the reaction hardly proceeded even after 30 minutes. Then, 0.18 kg of sodium hydroxide was added and further reacted for 60 minutes to completely dissolve the PET flakes. (2) While filtering this with a filter, it was transferred to a cooling tank and cooled to 80 ° C. In the subsequent steps, decolorization, deionization, crystallization / filtration, distillation of ethylene glycol, etc. were carried out by the method according to Example 1. And BHET were distilled. However,
The distillation yield of the purified BHET was limited to 75 wt%. Further, according to Example 1, the filtrate recovered from the crystallization / filtration step, and ethylene glycol obtained by distilling and purifying a part thereof, ethylene glycol recovered from the residual solvent distilling step, and the BHET distillation / purifying step were recovered. While adding the residual liquid to the new raw material and reusing it, the depolymerization reaction was repeatedly carried out by the batch system. The weight ratio of all ethylene glycol to all ethylene terephthalate units in the depolymerization reaction was 5.0 times the same as in the first batch, and the catalyst sodium hydroxide was 0.2 wt.
Adjusted to%. The cake liquid content after the crystallization filtration of the fifth batch was 52% by weight, and the BHET yield in the crystallization / solvent separation step was 79% by weight. The yield of purified BHET based on the raw material PET was 80 mol%. Purified BHET
The quality analysis values of are shown in Table 1 together with the results of Example 1. (3) This purified BHET was subjected to polycondensation by the same scale and operation as in Example 1. PET obtained
Table 1 also shows the quality analysis values of the above. In addition, the optical density in the table is a numerical value proportional to the concentration of the coloring matter measured by measuring the absorbance of a 10 wt% methanol solution of BHET at a wavelength of 380 nm and a cell length of 10 mm. In addition, the whiteness is a powder measured for BHET and a crystallized solid surface is measured for PET.

【００３４】[0034]

【表１】 [Table 1]

【００３５】実施例１の解重合反応工程滞留時間は、溶
融・脱ガス工程を含めても３０分あまりであり、ＤＥＧ
の副生するヒドロキシエチル基濃度の高い環境について
言えば、２０数分に過ぎない。一方、従来の方法である
比較例１の滞留時間は、９０分以上となった。解重合触
媒の有効量が把握しにくいため、反応時間は長めとする
必要があった。比較例１の状況では連続化はむつかし
い。取得ＢＨＥＴ中のＤＥＧＥＳＴＥＲは、表１に示し
た数値では比較例１は２.０ｗｔ％にとどまったが、こ
れはＢＨＥＴ蒸留工程の収率を低くし、より高沸点のＤ
ＥＧＥＳＴＥＲの留出を抑えた結果である。実施例１と
同じならＤＥＧＥＳＴＥＲは３ｗｔ％に近くなるはずで
ある。ＤＥＧＥＳＴＥＲとＤＥＧの副生を抑えることに
よって、実施例１の晶析工程の収率は大幅に向上してい
る。また、反応時間の短縮は、着色物の生成増大抑制に
も貢献し、取得精製ＢＨＥＴとＰＥＴの白度が明らかに
向上した。The residence time of the depolymerization reaction step in Example 1 was about 30 minutes including the melting and degassing step.
Regarding the environment in which the concentration of hydroxyethyl groups produced as a by-product is high, it is only 20 minutes. On the other hand, the retention time of Comparative Example 1, which is a conventional method, was 90 minutes or more. Since it is difficult to know the effective amount of the depolymerization catalyst, it was necessary to lengthen the reaction time. In the situation of Comparative Example 1, continuation is difficult. The DEGESTER in the obtained BHET was 2.0 wt% in Comparative Example 1 based on the numerical values shown in Table 1, but this lowers the yield of the BHET distillation step and results in higher boiling point D.
This is the result of suppressing the distillation of EGESTER. If it is the same as in Example 1, DEGESTER should be close to 3 wt%. The yield of the crystallization process of Example 1 is significantly improved by suppressing the generation of DEGESTER and DEG. In addition, the shortening of the reaction time also contributed to the suppression of the increase in the generation of colored products, and the whiteness of the obtained purified BHET and PET was clearly improved.

【００３６】実施例２ （１） ＰＥＴの重縮合工程、フィルム、ボトルなどの
成形加工工程、および紡糸・加工工程等の工程屑、規格
外品、中間品などから回収し、切断、破砕、洗浄などの
処理を経た、チップあるいは小塊状、テープ状、フレー
ク状、繊維状で、異種ポリマーの混在する恐れは少ない
が、性状の変化の大きな回収ＰＥＴが混在した、繊維油
剤などを洗浄した水の残留が多い（平均約１ｗｔ％）原
料を３０.５ｋｇ／ｈｒの速度で、スクリュー径４０ｍ
ｍの脱ガス孔を備えた二軸押出機に送入した。溶融温度
は２８０℃とし、水などの低沸点物を脱ガス孔から除き
がら溶融ポリマーを押し出した。 （２） 溶融ポリマーは、直ちに攪拌機つき予備解重合
反応器に送り、実施例１とほぼ同条件で予備解重合を行
った。ただし、触媒として解重合反応の全エチレンテレ
フタレート単位に対して０.２ｗｔ％となるナトリウム
メチラートを用い、ＢＨＥＴ蒸留工程から回収した蒸留
残液をここに加えた。また、予備解重合反応のエチレン
グリコールは溶融ポリマー（ＰＥＴ）に対して４０ｗｔ
％（１２.０ｋｇ／ｈｒ）とした。 （３） 反応液はフィルターを経て実施例１と同じ解重
合完結反応器に送入し、実施例１と同様にその第１槽に
晶析・濾過工程から回収した濾液と、その一部を蒸留精
製して得たエチレングリコールなどを送入した。反応全
エチレンテレフタレート単位に対して全エチレングリコ
ールが５.０重量倍となるように調整し、温度と各槽滞
留時間は２１０℃、１２分とした。 （４） 完結反応器から取り出されフィルターを経た反
応液は、原料ＰＥＴの着色剤、汚染物などのため淡灰色
となっていたが、透明な均一溶液であった。これを急冷
した後、実施例１と同じ設備を用い、ほぼ同様にして脱
色、脱イオン、次いで晶析・濾過、溶媒分離を行い、さ
らにＢＨＥＴを蒸留し、留出速度３６.１ｋｇ／ｈｒで
精製ＢＨＥＴを得た。晶析・濾過で得たケークの含液率
４２ｗｔ％、晶析・溶媒分離工程の（粗）ＢＨＥＴ収率
８６ｗｔ％、そして精製ＢＨＥＴの蒸留収率は８２ｗｔ
％、原料ＰＥＴに対する精製ＢＨＥＴ収率は９２ｍｏｌ
％であった。精製ＢＨＥＴの品質分析値を表２に示し
た。 （５） 薄膜蒸留器から溶融状態で取り出されたＢＨＥ
Ｔは、実施例１とほぼ同様にしてその大部分をフレーク
化し、一部を回分式重縮合器に送ってＰＥＴを製造し
た。ただし、重縮合触媒には生成するＰＥＴに対して３
００ｐｐｍの三酸化アンチモンを使用した。得られたＰ
ＥＴの品質分析値を表２に併記した。Example 2 (1) PET polycondensation process, film / bottle molding process, and spinning / processing process waste, substandard product, intermediate product, etc. are recovered, cut, crushed, and washed. Water that has been washed with a fiber oil agent, etc., that has undergone treatment such as chips or small blocks, tapes, flakes, fibers, and is unlikely to contain heterogeneous polymers, but has mixed recovered PET with large changes in properties. Raw material with a large amount of residue (average of about 1 wt%) at a speed of 30.5 kg / hr and a screw diameter of 40 m
It was fed into a twin-screw extruder equipped with m degassing holes. The melting temperature was 280 ° C., and low-boiling substances such as water were removed from the degassing holes to extrude the molten polymer. (2) The molten polymer was immediately sent to a preliminary depolymerization reactor equipped with a stirrer, and preliminarily depolymerized under the same conditions as in Example 1. However, 0.2 wt% of sodium methylate based on all ethylene terephthalate units of the depolymerization reaction was used as a catalyst, and the distillation residual liquid recovered from the BHET distillation step was added here. In addition, the ethylene glycol used in the preliminary depolymerization reaction is 40 wt% with respect to the molten polymer (PET).
% (12.0 kg / hr). (3) The reaction solution was passed through a filter into the same depolymerization completed reactor as in Example 1, and in the same manner as in Example 1, the filtrate recovered from the crystallization / filtration step in the first tank and a part thereof were collected. Ethylene glycol and the like obtained by distillation purification were fed. The reaction was adjusted so that the total ethylene glycol was 5.0 times the weight of the total ethylene terephthalate unit, and the temperature and residence time in each tank were 210 ° C. and 12 minutes. (4) The reaction liquid taken out from the completed reactor and passed through the filter was a light gray color due to the colorant and contaminants of the raw material PET, but was a transparent homogeneous solution. After quenching, the same equipment as in Example 1 was used to perform decolorization, deionization, crystallization / filtration, and solvent separation in substantially the same manner, and then BHET was distilled at a distillation rate of 36.1 kg / hr. Purified BHET was obtained. Liquid content of cake obtained by crystallization / filtration is 42 wt%, (crude) BHET yield of crystallization / solvent separation process is 86 wt%, and distillation yield of purified BHET is 82 wt%.
%, The purified BHET yield to the raw material PET is 92 mol
%Met. The quality analysis values of the purified BHET are shown in Table 2. (5) BHE taken out in a molten state from the thin film distiller
In the same manner as in Example 1, most of T was made into flakes, and part of the T was sent to a batch polycondensator to produce PET. However, for the polycondensation catalyst, 3 for PET produced
00 ppm antimony trioxide was used. Obtained P
The quality analysis value of ET is also shown in Table 2.

【００３７】比較例２ （１） 実施例２と同じ回収ＰＥＴ混合物６１ｋｇとエ
チレングリコール３００ｋｇを攪拌機つきオートクレー
ブに仕込み、解重合触媒としてナトリウムメチラート
０.１２ｋｇを加えて、２１０℃で低沸点物を留去しな
がら反応させた。３時間後ＰＥＴ固体片の大部分が溶解
したが、わずかに未溶解片が残った。これをフィルター
で濾過しながら冷却槽に移して９０℃まで冷却したが、
フィルターで捕集された未溶解物は０.６ｋｇで、その
うちＰＥＴは０.４ｋｇであった。以後の工程は実施例
２に準じる方法で脱色、脱イオン、晶析・濾過、溶媒分
離、およびＢＨＥＴ蒸留を行った。ただし、精製ＢＨＥ
Ｔの蒸留収率は７６ｗｔ％とした。 （２） さらに、実施例２に準じて、回収濾液、蒸留精
製エチレングリコール、および回収したＢＨＥＴ蒸留残
液などを再使用しながら、くりかえし回分式解重合反応
を行った。解重合反応の全エチレンテレフタレート単位
に対する全エチレングリコールの重量比は第１バッチと
同じ５.０倍、触媒のナトリウムメチラートは０.２ｗｔ
％に調整した。その第５バッチの晶析・濾過後のケーク
含液率は５０ｗｔ％、晶析・溶媒分離工程のＢＨＥＴ収
率は８１ｗｔ％であった。また、原料ＰＥＴに対する精
製ＢＨＥＴの収率は８３ｍｏｌ％であった。精製ＢＨＥ
Ｔの品質分析値を実施例２の結果とともに表２に示し
た。 （３） この精製ＢＨＥＴについて実施例２と同じ触媒
を用いて、ほぼ同じ規模、操作で重縮合を行った。得ら
れたＰＥＴの品質分析値を表２に併記した。Comparative Example 2 (1) 61 kg of the same recovered PET mixture as in Example 2 and 300 kg of ethylene glycol were charged into an autoclave equipped with a stirrer, 0.12 kg of sodium methylate as a depolymerization catalyst was added, and a low boiling point substance at 210 ° C. was added. The reaction was carried out while distilling off. After 3 hours most of the solid PET pieces had dissolved, but a small amount of undissolved pieces remained. While filtering this with a filter, it was transferred to a cooling tank and cooled to 90 ° C.
Undissolved material collected by the filter was 0.6 kg, of which PET was 0.4 kg. In the subsequent steps, decolorization, deionization, crystallization / filtration, solvent separation, and BHET distillation were carried out by the method according to Example 2. However, purified BHE
The distillation yield of T was 76 wt%. (2) Further, in accordance with Example 2, while reusing the recovered filtrate, the distilled and purified ethylene glycol, the recovered BHET distillation residual liquid and the like, the batchwise depolymerization reaction was repeated. The weight ratio of all ethylene glycol to all ethylene terephthalate units in the depolymerization reaction was 5.0 times the same as in the first batch, and the catalyst sodium methylate was 0.2 wt.
Adjusted to%. The liquid content of the cake after crystallization / filtration of the fifth batch was 50 wt%, and the BHET yield in the crystallization / solvent separation step was 81 wt%. The yield of purified BHET based on the raw material PET was 83 mol%. Purified BHE
The quality analysis values of T are shown in Table 2 together with the results of Example 2. (3) The purified BHET was subjected to polycondensation using the same catalyst as in Example 2 and at substantially the same scale and operation. The quality analysis values of the obtained PET are also shown in Table 2.

【００３８】[0038]

【表２】 [Table 2]

【００３９】実施例２と比較例２の解重合反応工程滞留
時間、取得精製ＢＨＥＴ及びＰＥＴの品質、収率等を比
較すると、実施例１と比較例１の場合と同様の大きな差
が認められる。その原因の一つは、原料ＰＥＴの性状の
斑および水分の悪影響が従来の方法である比較例におい
て大きく現れていることである。ポリ塩化ビニールが混
在しない場合でも、反応性の悪い固体片のために反応時
間（滞留時間）を長くしなければならず、水分が解重合
触媒のアルコレートの活性を低下させている。言うまで
もなく均一溶液反応による連続化が、生産性、品質、収
率のいずれにも好影響を与えている。Comparing the residence time of the depolymerization reaction step, the quality of the obtained purified BHET and PET, the yield and the like between Example 2 and Comparative Example 2, the same great difference as in Example 1 and Comparative Example 1 was observed. . One of the causes is that the unevenness of the properties of the raw material PET and the bad influence of water are largely shown in the comparative example which is the conventional method. Even when polyvinyl chloride is not mixed, the reaction time (residence time) must be lengthened due to the solid pieces having poor reactivity, and water reduces the activity of the alcoholate of the depolymerization catalyst. Needless to say, the continuous process by the homogeneous solution reaction has a favorable effect on productivity, quality and yield.

【００４０】[0040]

【発明の効果】本発明方法によって得られるメリット、
即ち、生産性と操業性、品質、収率の向上、原料を選ば
ぬこと等が驚くべきものであることは、既に詳しく述べ
た通りである。また、本発明は繊維、フィルム、ボトル
などの高品質ＰＥＴ成形品と、高品質モノマーである精
製ＢＨＥＴのケミカルリサイクルの経済性を改善し、い
わゆる環境問題、省資源・省エネ問題の解決に大きく貢
献する。Advantages obtained by the method of the present invention,
That is, it has been already described in detail that the productivity, operability, quality, yield, and selection of raw materials are surprising. In addition, the present invention improves the economical efficiency of chemical recycling of high-quality PET molded products such as fibers, films and bottles and refined BHET which is a high-quality monomer, and greatly contributes to solving so-called environmental problems, resource saving and energy saving problems. To do.

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Claims (4)

【特許請求の範囲】[Claims] 【請求項１】 ポリエチレンテレフタレートを溶融およ
び脱ガスし、該ポリエチレンテレフタレートの１５乃至
５０重量％に当る量のエチレングリコールを、解重合触
媒の存在下に予備解重合反応させて低重合体組成物と
し、次いでこの低重合体組成物をポリエチレンテレフタ
レートの２乃至１０重量倍のエチレングリコールに溶解
して１８０乃至２５０℃において反応させ、解重合を完
結することを特徴とするビス−β−ヒドロキシエチルテ
レフタレートの製造法。1. A low polymer composition is prepared by melting and degassing polyethylene terephthalate, and preliminarily depolymerizing an amount of ethylene glycol corresponding to 15 to 50% by weight of the polyethylene terephthalate in the presence of a depolymerization catalyst. Then, this low polymer composition is dissolved in 2 to 10 times by weight of polyethylene terephthalate in ethylene glycol and reacted at 180 to 250 ° C. to complete depolymerization, and bis-β-hydroxyethyl terephthalate. Manufacturing method. 【請求項２】 予備解重合反応を２６０℃乃至３００℃
の範囲で行う請求項１に記載の方法。2. The preliminary depolymerization reaction is carried out at 260 ° C. to 300 ° C.
The method according to claim 1, which is performed in the range of. 【請求項３】 予備解重合反応および／または解重合反
応を連続式で行う請求項１に記載の方法。3. The method according to claim 1, wherein the preliminary depolymerization reaction and / or the depolymerization reaction is carried out continuously. 【請求項４】 請求項１の方法で製造されたビス−β−
ヒドロキシエチルテレフタレートを原料の一部または全
部として使用して、重縮合触媒の存在下に重合すること
を特徴とするポリエチレンテレフタレートの製造法。4. Bis-β-produced by the method of claim 1.
A method for producing polyethylene terephthalate, which comprises polymerizing in the presence of a polycondensation catalyst using hydroxyethyl terephthalate as a part or all of a raw material.
JP2001247750A 2001-08-17 2001-08-17 METHOD FOR PRODUCING BIS-beta-HYDROXYETHYL TEREPHTHALATE Withdrawn JP2003055300A (en)

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