JP3559769B2 - Method for producing aliphatic polyester and method for recycling starch - Google Patents

Description

（式中、ｎは１０〜６０００の整数を示す。）
デンプンを加水分解してグルコースを得る工程と、
該グルコースを酸化してグルコノラクトンを得る工程と、
該グルコノラクトンを還元してカプロン酸を得る工程と、
該カプロン酸を塩素化して５−クロロカプロン酸を得る工程と、
該５−クロロカプロン酸を環化してδ−カプロラクトンを得る工程と、
該δ−カプロラクトンを開環重合せしめる工程と、
を含むことを特徴とする脂肪族ポリエステルの製造方法が提供される。
【００１３】
また、下記式（Ｉ）で示される脂肪族ポリエステルの製造方法であって、
【００１４】
【化４】

（式中、ｎは１０〜６０００の整数を示す。）
デンプンを加水分解してグルコースを得る工程と、
該グルコースを酸化してグルコン酸を得る工程と、
該グルコン酸を還元してカプロン酸を得る工程と、
該カプロン酸を塩素化して５−クロロカプロン酸を得る工程と、
該５−クロロカプロン酸を環化してδ−カプロラクトンを得る工程と、
該δ−カプロラクトンを開環重合せしめる工程と、
を有することを特徴とする脂肪族ポリエステルの製造方法が提供される。
【００１５】
【発明の実施の形態】
本発明においては、グルコノラクトンが脂肪族ポリエステルのモノマーとして使用可能な程度に高純度で効率的にカプロン酸に誘導される。また、グルコン酸が脂肪族ポリエステルのモノマーとして使用可能な程度に高純度で効率的にカプロン酸に誘導される。この結果、デンプンからグルコースを経て得られるところのカプロン酸を用いて、脂肪族ポリエステルを製造すること、即ち、デンプンを出発物質として高品質なプラスチックを得ることが可能となる。よって、廃デンプンを原料として得られる脂肪族ポリエステルを製造することが可能となり、デンプンを再資源化することができる。
【００１６】
以下に各工程を説明する。
【００１７】
（デンプンからグルコース）
デンプンからグルコースへの変換は、例えば、硫酸などの希酸による加水分解方法、アミラーゼ及びマルターゼなどの酵素による加水分解方法、あるいは、超臨界水による加水分解方法等が挙げられる。
【００１８】
（グルコースからグルコノラクトン又はグルコン酸）
グルコースからグルコノラクトンへの変換は、グルコースを臭素酸化する方法やグルコース酸化酵素であるノタチンを用いる方法等が挙げられる。
【００１９】
また、グルコースからグルコン酸への変換は、臭素を飽和させた硫酸中でグルコースを酸化、加水分解して得る方法、グルコース溶液の電解酸化による方法、あるいはペニシリウム属の細菌を用いたグルコン酸発酵による方法等が挙げられる。
【００２０】
（グルコノラクトン又はグルコン酸からカプロン酸）
グルコノラクトン又はグルコン酸をカプロン酸へ変換する工程は、本発明において重要であり、この工程をヨウ化水素酸および赤リンによる還元で行うことが、収率および選択率などの観点から好ましい。この際、実質的に、グルコノラクトン又はグルコン酸の水酸基のみが還元される。
【００２１】
この工程の反応条件は、得られるカプロン酸の収量および純度などを考慮して注意深く選択される。
【００２２】
具体的には、還元に用いる赤リンの量は、十分な収率を確保する観点から、グルコノラクトン又はグルコン酸に対して１．５モル倍以上が好ましく、１．７モル倍以上がより好ましく、１．８モル倍以上が更に好ましい。一方、副反応物を抑制する観点から、３．０モル倍以下が好ましく、２．７モル倍以下がより好ましく、２．４モル倍以下が更に好ましい。
【００２３】
また、還元に用いるヨウ化水素酸は、十分な収率を確保する観点から、濃度が５０質量％以上６０質量％以下のものをグルコノラクトン又はグルコン酸に対して好ましくは３０質量倍以上、より好ましくは３５質量倍以上、更に好ましくは４０質量倍以上を使用する。一方、副反応物を抑制する観点から、７０質量倍以下が好ましく、６５質量倍以下がより好ましく、６０質量倍以下が更に好ましい。
【００２４】
グルコノラクトン又はグルコン酸と、赤リンと、ヨウ化水素酸とを含有する混合物は還流するまで加熱され、還元反応が完了するまで還流状態を維持する。還流時間は、十分な収率を確保する観点から、１０時間以上が好ましく、１３時間以上がより好ましく、１５時間以上が更に好ましい。一方、副反応物を抑制する観点から、３０時間以下が好ましく、２７時間以下が好ましく、２５時間以下が更に好ましい。
【００２５】
（カプロン酸から５−クロロカプロン酸）
カプロン酸から５−クロロカプロン酸への変換は、カプロン酸を濃硫酸中でＮ−クロロジイソプロピルアミンと反応させて塩素化する方法が挙げられる。この反応については、Ｎ．Ｃ．Ｄｅｎｏら、Ｊ．Ａｍ．Ｃｈｅｍ．Ｓｏｃ．誌、第９３号、第４３８〜４４０頁、１９７１年刊に記載されている。
【００２６】
（５−クロロカプロン酸からδ−カプロラクトン）
５−クロロカプロン酸から、下記式（ＩＩ）で表されるδ−カプロラクトンへの変換は、５−クロロカプロン酸を水酸化ナトリウム水溶液中で煮沸する方法が挙げられる。
【００２７】
【化５】

（δ−カプロラクトンから脂肪族ポリエステル；開環重合）
本発明では、δ−カプロラクトンの開環重合に際し、重合触媒としては、公知の開環重合触媒を用いることができる。例えば、二塩化スズ、四塩化スズ、テトラ−ｎ−ブトキシゲルマニウム、テトラメトキシゲルマニウム、テトラエトキシゲルマニウム、トリエトキシアルミニウム、トリ−ｎ−プロポキシアルミニウム、トリ−ｉｓｏ−プロポキシアルミニウム、トリ−ｎ−ブトキシアルミニウム、トリ−ｉｓｏ−ブトキシアルミニウム、塩化アルミニウム、トリエチルアルミニウム、トリメチルアルミニウム、ジ−ｉｓｏ−プロピル亜鉛、ジメチル亜鉛、ジエチル亜鉛、塩化亜鉛、テトラ−ｎ−プロポキシチタン、テトラ−ｎ−ブトキシチタン、テトラ−ｔ−ブトキシチタン、テトラエトキシジルコニウム、テトラメトキシジルコニウム、テトラ−ｉｓｏ−プロポキシジルコニウム、テトラ−ｎ−ブトキシジルコニウム、テトラ−ｉｓｏ−ブトキシジルコニウム、テトラ−ｔ−ブトキシジルコニウム、Ｌａ、Ｎｄ、Ｓｍ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ等の有機希土類化合物等を用いることができる。
【００２８】
重合触媒の使用量は、δ−カプロラクトンと重合開始剤の合計量に対し、０．０１〜１０質量％、好ましくは、０．０５〜５質量％である。
【００２９】
本発明では、δ−カプロラクトンの開環重合に際し、重合開始剤としては、公知の重合開始剤を用いることができる。例えば、メタノール、エタノール、１−プロパノール、２−プロパンール、各種ブタノール、フェノール等のモノオール、エチレングリコール、１，３−プロパンジオール、１，４−ブタンジオール、ジエチレングリコール、１，５−ペンタンジオール、１，６−ヘキサンジオール、１，７−ヘプタンジオール、１，８−オクタンジオール、１，１０−デカンジオール等のジオール、グリセリン、トリメチロールプロパン等のトリオール、ネオペンチルグリコール、ペンタエリスリトール等のポリオールを用いることができる。また、これらは、単独でも２種類以上を併用してもよい。
【００３０】
本発明で使用する重合開始剤とδ−カプロラクトンとのモル比は、目的とする脂肪族ポリエステルの重合率に応じて適宜選択することができる。重合開始剤とδ−カプロラクトンとのモル比は、１：１〜１：５０００モル比、好ましくは、１：１〜１：２０００モル比である。
【００３１】
δ−カプロラクトンの開環重合は、δ−カプロラクトンに重合触媒と重合開始剤を添加して不活性ガスの存在下、あるいは、減圧下で重合反応させる。好ましくは、簡便さから窒素雰囲気下の常圧で行うのがよい。
【００３２】
δ−カプロラクトンの開環重合の反応温度及び時間は、任意に選択できる。反応温度は、好ましくは、５０〜２００℃、より好ましくは、１００〜１８０℃の範囲である。５０℃以上であれば、反応速度は十分速い。また、２００℃以下であれば、酸化反応による脂肪族ポリエステルの着色や生成する脂肪族ポリエステルの分解反応等が抑制される。反応時間も任意に選択できるが、生成する脂肪族ポリエステルの品質に影響を与えない範囲で行うことができる。
【００３３】
δ−カプロラクトンの開環重合は、溶媒中で行うことができる。溶媒は、δ−カプロラクトン、重合触媒、重合開始剤と反応しない不活性溶媒であり、好ましくは、トルエン、キシレン等の芳香族炭化水素、ヘキサン、シクロヘキサン等の脂肪族又は脂環式炭化水素を用いることができる。これらの溶媒は、実質的には、無水のものが望ましい。
【００３４】
δ−カプロラクトンの開環重合によって得られる脂肪族ポリエステルの重量平均分子量は、ポリスチレン換算で１０００〜１００００００、好ましくは、３００００〜５０００００である。
【００３５】
この様にして得られる脂肪族ポリエステルは、これまで種々の分野で用いられているプラスチック材料を代替するプラスチック材料として用いることができる。そして重量平均分子量や含まれる官能基等を変化させることによって、産業上の多くの分野に適用することができる。例えば、グリコールを重合開始剤とした重量平均分子量１０００〜５０００の脂肪族ポリエステルは、水酸基を有することを活かして、例えば、ポリウレタンの原料や、塗料等の材料として非常に有用である。更に、重量平均分子量が５００００を超える脂肪族ポリエステルは、実用的な機械的強度を持ち、プラスチック成形品、フィルム、ホットメルト接着剤等に用いることができる。
【００３６】
【実施例】
以下、実施例により本発明を更に具体的に説明する。但し、本発明は、これらの実施例に限定されるものではない。また、特に明記しない限り、試薬等は市販の高純度品を使用した。
【００３７】
（実施例１）
デンプン（和光純薬工業製）５００質量部を水４５００質量部に投入し、加温しながら溶解した。これに３モル／ｌ硫酸５０００質量部を加え、８０℃で５時間攪拌した。反応終了後、無水炭酸ナトリウムを加えて水溶液を中和した後、イオン交換樹脂カラム（オルガノ社製、アンバライトＩＲ−１２０Ｂ）を通過させ、溶媒を留去した。そして、反応混合物を分離精製し、グルコース３００質量部を得た。
【００３８】
得られたグルコースを、ＦＴ−ＮＭＲ ＤＰＸ４００（Ｂｒｕｋｅｒ製）を用い、^１３Ｃ―ＮＭＲ（１００ＭＨｚ、ＤＭＳＯ−ｄ_６）を測定した。その結果、α型グルコースに由来するピークのδ値として９２．１２ｐｐｍ、７３．０４ｐｐｍ、７２．２９ｐｐｍ、７１．８０ｐｐｍ、７０．５８ｐｐｍ、６１．２０ｐｐｍを確認した。また、β型グルコースに由来するピークのδ値として９６．７９ｐｐｍ、７６．７０ｐｐｍ、７６．５９ｐｐｍ、７４．７８ｐｐｍ、７０．３０ｐｐｍ、６１．００ｐｐｍを確認した。
【００３９】
次に、１２質量％の炭酸バリウム水溶液８０００質量部に二酸化炭素を飽和した後、これに臭素３３０質量部と、上で得られたグルコース３００質量部とを加え、２５℃で３０分間攪拌して、下記化学式（ＩＩＩ）で表わされるグルコノラクトン２５０質量部を得た。
【００４０】
【化６】

得られたグルコノラクトンの^１３Ｃ―ＮＭＲ（１００ＭＨｚ、ＤＭＳＯ−ｄ_６）を測定したところ、δ値として１７１．８８ｐｐｍ、８１．２３ｐｐｍ、７３．７９ｐｐｍ、７１．４３ｐｐｍ、６７．８２ｐｐｍ、６０．１４ｐｐｍを確認した。
【００４１】
このグルコノラクトン２５０質量部と赤リン８７質量部をヨウ化水素酸（５５質量％）１２０００質量部に加え、２０時間加熱還流を行った。そして、反応混合物を濾過し、濾液をエーテル抽出した後、５％亜硫酸水素ナトリウム水溶液で洗浄した。その後、エーテルを留去し、減圧蒸留してカプロン酸１４７質量部を得た。このカプロン酸の^１３Ｃ−ＮＭＲ（１００ＭＨｚ、ＣＤＣｌ_３）を測定したところ、δ値として１３．９０ｐｐｍ、２２．４２ｐｐｍ、２４．５１ｐｐｍ、３１．３６ｐｐｍ、３４．２２ｐｐｍ、１８０．７９ｐｐｍを確認した。
【００４２】
得られたカプロン酸１４７質量部と当量のＮ−クロロジイソプロピルアミンを８４％硫酸１０００質量部に加え、２５℃、５時間反応させて、５−クロロカプロン酸１７７質量部を得た。その後、この５−クロロカプロン酸１７７質量部を当量の水酸化ナトリウム水溶液と煮沸して、δ−カプロラクトン１２９質量部を得た。得られたδ−カプロラクトンの^１３Ｃ−ＮＭＲ（１００ＭＨｚ、ＣＤＣｌ_３）を測定したところ、δ値として１９．９０ｐｐｍ、２０．８８ｐｐｍ、３４．２７ｐｐｍ、３５．３１ｐｐｍ、７０．４４ｐｐｍ、１７２．８４ｐｐｍを確認した。
【００４３】
このδ−カプロラクトン１２９質量部を窒素雰囲気下、１５５℃まで加熱し、これにトリ−ｉｓｏ−プロポキシアルミニウム０．３９質量部、ジエチレングリコール０．７７質量部を添加し、開環重合して脂肪族ポリエステルを得た。重合時間は１０時間であり、得られた脂肪族ポリエステルの重量平均分子量は２９万であった。
【００４４】
得られた脂肪族ポリエステルの^１３Ｃ―ＮＭＲ（１００ＭＨｚ、ＣＤＣｌ_３）を測定したところ、δ値として１９．９５ｐｐｍ、２０．８２ｐｐｍ、３４．４６ｐｐｍ、３５．２６ｐｐｍ、７０．３１ｐｐｍ、１７３．３７ｐｐｍを観測し、目的の脂肪族ポリエステルが合成されたことを確認した。
【００４５】
（実施例２）
実施例１と同様にして得たグルコース３００質量部を臭素で飽和させた１３．５モル／ｌの硫酸２５００質量部中で酸化、加水分解して下記化学式（ＩＶ）で表わされるグルコン酸２９０質量部を得た。
【００４６】
【化７】

次に、得られたグルコン酸２９０質量部と赤リン１００質量部をヨウ化水素酸（５５質量％）１４０００質量部に加え、２０時間加熱還流を行た。その後、実施例１と同様の処理を行い、カプロン酸１５５質量部を得た。
【００４７】
その後、８４％硫酸１０００質量部にカプロン酸１５５質量部と当量のＮ−クロロジイソプロピルアミンを加え、２５℃、５時間反応させて、５−クロロカプロン酸１８７質量部を得た。この５−クロロカプロン酸１８７質量部を当量の水酸化ナトリウム水溶液と煮沸して、δ−カプロラクトン１３６質量部を得た。
【００４８】
得られたδ−カプロラクトン１３６質量部を窒素雰囲気下、１６０℃まで加熱し、これに、ジ−ｉｓｏ−プロピル亜鉛０．４１質量部、１，４−ブタンジオール０．８２質量部を添加し、開環重合して脂肪族ポリエステルを得た。重合時間は１０時間であり、得られた脂肪族ポリエステルの重量平均分子量は２２万であった。また、^１３Ｃ―ＮＭＲを測定したところ、実施例１と同様のスペクトルが得られ、目的の脂肪族ポリエステルが合成されたことを確認した。
【００４９】
（物性評価）
実施例１及び２で合成した脂肪族ポリエステルを用い、表１に示す物性評価を行った。また、比較例１として、セルグリーン（ダイセル化学工業社製、ポリカプロラクトン系プラスチック、Ｐ−Ｈ７）の物性も評価した。
【００５０】
【表１】

以上の結果から、実施例１及び２で合成した各々の脂肪族ポリエステルは、比較例１に用いた、強度および伸度に優れたダイセル化学製の脂肪族ポリエステル（Ｐ−Ｈ７）と同等もしくはそれ以上の物性を有しており、従来のプラスチック成形品の代替品として十分に利用が可能であることが分かった。
【００５１】
【発明の効果】
以上説明したように、本発明は、デンプンからグルコースを経て得られるδ−カプロラクトンを開環重合する事によって脂肪族ポリエステルを製造することができ、その機械的強度等の物性も充分であり、プラスチック成形品として利用が可能である。更に、このことは、石油の代替であるデンプンを出発原料として高品質なプラスチックを得るという、デンプンの効率的な資源化の確立に道を開くものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an aliphatic polyester and a method for recycling starch.
[0002]
[Prior art]
Conventional general-purpose plastic products are polymer compounds mainly synthesized from petroleum resources. That is, polymer compounds such as polyester, polystyrene, nylon, polyethylene, polyvinyl chloride, polyimide, and polycarbonate are almost always produced from monomers obtained from petroleum as a raw material.
[0003]
For example, a monomer of poly (ε-caprolactone), which is one of the aliphatic polyesters, is ε-caprolactone, which is generally obtained by oxidizing cyclohexanone (JP-A-11-158172). .
[0004]
However, petroleum is a finite resource and is expected to be depleted over time. Therefore, there is a strong demand for a technology for producing general-purpose plastic products from a new raw material instead of petroleum, that is, a renewable raw material.
[0005]
Based on such recognition, the present inventors have focused on starch as a raw material instead of petroleum, and have studied producing an aliphatic polyester from waste starch.
[0006]
Starch is a polymer compound in which D-glucose is dehydrated and polymerized, and is an important polysaccharide together with cellulose. Worldwide starch production (corn yield) is about 400-500 million tons / year, making it the most produced and renewable resource of natural resources.
[0007]
[Problems to be solved by the invention]
As described above, one of the useful methods for producing an aliphatic polyester is a method in which a caprolactone is used as a monomer and is subjected to ring-opening polymerization. As an example of caprolactones, δ-caprolactone readily undergoes ring opening polymerization to give aliphatic polyesters. Such aliphatic polyesters can be used in many industrial fields as plastic molded articles, films, hot melt adhesives and the like.
[0008]
Caprolactones are obtained by cyclizing caproic acids. Therefore, when an aliphatic polyester is produced using waste starch as a starting material, it is necessary to efficiently convert the waste starch into caproic acids.
[0009]
However, it is not well known that caproic acids are efficiently derived from waste starch with such a high purity as to be usable as a monomer of an aliphatic polyester.
[0010]
In view of the above circumstances, an object of the present invention is to produce an aliphatic polyester using caproic acid obtained from starch via glucose, that is, to obtain a high-quality plastic starting from starch. That is. ADVANTAGE OF THE INVENTION By this invention, it becomes possible to manufacture the aliphatic polyester obtained from a starch as a raw material, and can recycle a starch.
[0011]
[Means for Solving the Problems]
According to the present invention for achieving the above object, there is provided a method for producing an aliphatic polyester represented by the following formula (I),
[0012]
Embedded image

(In the formula, n represents an integer of 10 to 6000.)
Hydrolyzing the starch to obtain glucose;
Oxidizing the glucose to obtain gluconolactone;
Reducing the gluconolactone to obtain caproic acid;
Chlorinating the caproic acid to obtain 5-chlorocaproic acid;
Cyclizing the 5-chlorocaproic acid to obtain δ-caprolactone;
A step of subjecting the δ-caprolactone to ring-opening polymerization,
And a process for producing an aliphatic polyester.
[0013]
A method for producing an aliphatic polyester represented by the following formula (I),
[0014]
Embedded image

(In the formula, n represents an integer of 10 to 6000.)
Hydrolyzing the starch to obtain glucose;
Oxidizing the glucose to obtain gluconic acid;
Reducing the gluconic acid to obtain caproic acid;
Chlorinating the caproic acid to obtain 5-chlorocaproic acid;
Cyclizing the 5-chlorocaproic acid to obtain δ-caprolactone;
A step of subjecting the δ-caprolactone to ring-opening polymerization,
The production method of the aliphatic polyester characterized by having is provided.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, gluconolactone is efficiently derived into caproic acid with such a high purity that it can be used as a monomer of the aliphatic polyester. In addition, gluconic acid is efficiently derived to caproic acid with such a high purity that it can be used as a monomer of the aliphatic polyester. As a result, it is possible to produce an aliphatic polyester by using caproic acid obtained from starch via glucose, that is, to obtain a high-quality plastic using starch as a starting material. Therefore, it is possible to produce an aliphatic polyester obtained from waste starch as a raw material, and the starch can be recycled.
[0016]
Hereinafter, each step will be described.
[0017]
(From starch to glucose)
The conversion of starch into glucose includes, for example, a hydrolysis method using a dilute acid such as sulfuric acid, a hydrolysis method using an enzyme such as amylase and maltase, or a hydrolysis method using supercritical water.
[0018]
(From glucose to gluconolactone or gluconic acid)
Conversion of glucose to gluconolactone includes a method of bromine oxidation of glucose and a method of using notatin, which is a glucose oxidase.
[0019]
The conversion of glucose to gluconic acid is achieved by oxidizing and hydrolyzing glucose in sulfuric acid saturated with bromine, by a method of electrolytic oxidation of a glucose solution, or by gluconic acid fermentation using bacteria of the genus Penicillium. Method and the like.
[0020]
(Gluconolactone or gluconic acid to caproic acid)
The step of converting gluconolactone or gluconic acid to caproic acid is important in the present invention, and it is preferable to perform this step by reduction with hydroiodic acid and red phosphorus from the viewpoint of yield and selectivity. At this time, substantially only the hydroxyl group of gluconolactone or gluconic acid is reduced.
[0021]
The reaction conditions in this step are carefully selected in consideration of the yield and purity of the obtained caproic acid.
[0022]
Specifically, the amount of red phosphorus used for the reduction is preferably 1.5 mol times or more, more preferably 1.7 mol times or more with respect to gluconolactone or gluconic acid, from the viewpoint of ensuring a sufficient yield. It is more preferably 1.8 mole times or more. On the other hand, from the viewpoint of suppressing by-products, the molar ratio is preferably 3.0 mol times or less, more preferably 2.7 mol times or less, and even more preferably 2.4 mol times or less.
[0023]
From the viewpoint of securing a sufficient yield, the hydroiodic acid used for the reduction is preferably one having a concentration of 50% by mass or more and 60% by mass or less, preferably 30% by mass or more of gluconolactone or gluconic acid, More preferably, it is 35 times by mass or more, and further preferably, 40 times by mass or more. On the other hand, from the viewpoint of suppressing by-products, the amount is preferably 70 times by mass or less, more preferably 65 times by mass or less, and even more preferably 60 times by mass or less.
[0024]
A mixture containing gluconolactone or gluconic acid, red phosphorus, and hydroiodic acid is heated to reflux and maintained at reflux until the reduction reaction is completed. The reflux time is preferably at least 10 hours, more preferably at least 13 hours, even more preferably at least 15 hours, from the viewpoint of ensuring a sufficient yield. On the other hand, from the viewpoint of suppressing by-products, the time is preferably 30 hours or less, preferably 27 hours or less, and more preferably 25 hours or less.
[0025]
(From caproic acid to 5-chlorocaproic acid)
Conversion of caproic acid to 5-chlorocaproic acid includes a method of reacting caproic acid with N-chlorodiisopropylamine in concentrated sulfuric acid to chlorinate. For this reaction, see N.M. C. Deno et al. Am. Chem. Soc. Journal, No. 93, pp. 438-440, published in 1971.
[0026]
(From 5-chlorocaproic acid to δ-caprolactone)
Conversion of 5-chlorocaproic acid to δ-caprolactone represented by the following formula (II) includes a method of boiling 5-chlorocaproic acid in an aqueous sodium hydroxide solution.
[0027]
Embedded image

(From δ-caprolactone to aliphatic polyester; ring-opening polymerization)
In the present invention, a known ring-opening polymerization catalyst can be used as a polymerization catalyst in the ring-opening polymerization of δ-caprolactone. For example, tin dichloride, tin tetrachloride, tetra-n-butoxygermanium, tetramethoxygermanium, tetraethoxygermanium, triethoxyaluminum, tri-n-propoxyaluminum, tri-iso-propoxyaluminum, tri-n-butoxyaluminum, Tri-iso-butoxy aluminum, aluminum chloride, triethyl aluminum, trimethyl aluminum, di-iso-propyl zinc, dimethyl zinc, diethyl zinc, zinc chloride, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-t- Butoxy titanium, tetraethoxy zirconium, tetramethoxy zirconium, tetra-iso-propoxy zirconium, tetra-n-butoxy zirconium, tetra-iso-butoxy zirconium Beam can be used tetra -t- butoxy zirconium, La, Nd, Sm, Er, Tm, Yb, the organic rare earth compounds such Lu like.
[0028]
The amount of the polymerization catalyst used is 0.01 to 10% by mass, and preferably 0.05 to 5% by mass, based on the total amount of δ-caprolactone and the polymerization initiator.
[0029]
In the present invention, in the ring-opening polymerization of δ-caprolactone, a known polymerization initiator can be used as the polymerization initiator. For example, methanol, ethanol, 1-propanol, 2-propaneol, various butanols, monools such as phenol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, Diols such as 2,6-hexanediol, 1,7-heptanediol, 1,8-octanediol and 1,10-decanediol, triols such as glycerin and trimethylolpropane, and polyols such as neopentyl glycol and pentaerythritol. be able to. These may be used alone or in combination of two or more.
[0030]
The molar ratio between the polymerization initiator and δ-caprolactone used in the present invention can be appropriately selected according to the desired degree of polymerization of the aliphatic polyester. The molar ratio of the polymerization initiator to δ-caprolactone is from 1: 1 to 1: 5000, preferably from 1: 1 to 1: 2000.
[0031]
In the ring-opening polymerization of δ-caprolactone, a polymerization catalyst and a polymerization initiator are added to δ-caprolactone to carry out a polymerization reaction in the presence of an inert gas or under reduced pressure. Preferably, it is carried out at normal pressure under a nitrogen atmosphere for simplicity.
[0032]
The reaction temperature and time of the ring-opening polymerization of δ-caprolactone can be arbitrarily selected. The reaction temperature is preferably in the range of 50 to 200C, more preferably 100 to 180C. If it is 50 ° C. or higher, the reaction rate is sufficiently fast. When the temperature is 200 ° C. or lower, coloring of the aliphatic polyester due to the oxidation reaction, decomposition reaction of the aliphatic polyester to be formed, and the like are suppressed. Although the reaction time can be arbitrarily selected, the reaction can be performed within a range that does not affect the quality of the aliphatic polyester to be produced.
[0033]
The ring-opening polymerization of δ-caprolactone can be performed in a solvent. The solvent is an inert solvent that does not react with δ-caprolactone, a polymerization catalyst, and a polymerization initiator, preferably, an aromatic hydrocarbon such as toluene and xylene, hexane, an aliphatic or alicyclic hydrocarbon such as cyclohexane is used. be able to. Desirably, these solvents are substantially anhydrous.
[0034]
The weight average molecular weight of the aliphatic polyester obtained by ring-opening polymerization of δ-caprolactone is 1000 to 1,000,000, preferably 30,000 to 500,000 in terms of polystyrene.
[0035]
The aliphatic polyester thus obtained can be used as a plastic material that replaces plastic materials used in various fields. By changing the weight average molecular weight, the contained functional groups, and the like, the present invention can be applied to many industrial fields. For example, an aliphatic polyester having a weight-average molecular weight of 1,000 to 5,000 using glycol as a polymerization initiator is very useful as a raw material of polyurethane or a material of a paint, for example, by utilizing the fact that it has a hydroxyl group. Further, an aliphatic polyester having a weight average molecular weight of more than 50,000 has practical mechanical strength and can be used for plastic molded articles, films, hot melt adhesives and the like.
[0036]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Unless otherwise specified, commercially available high-purity reagents were used.
[0037]
(Example 1)
500 parts by mass of starch (manufactured by Wako Pure Chemical Industries) was charged into 4500 parts by mass of water and dissolved while heating. 5000 parts by mass of 3 mol / l sulfuric acid was added thereto, followed by stirring at 80 ° C. for 5 hours. After the completion of the reaction, the aqueous solution was neutralized by adding anhydrous sodium carbonate, and then passed through an ion exchange resin column (Amberite IR-120B, manufactured by Organo Co., Ltd.) to distill off the solvent. Then, the reaction mixture was separated and purified to obtain 300 parts by mass of glucose.
[0038]
¹³ C-NMR (100 MHz, DMSO-d ₆ ) of the obtained glucose was measured using FT-NMR DPX400 (manufactured by Bruker). As a result, 92.12 ppm, 73.04 ppm, 72.29 ppm, 71.80 ppm, 70.58 ppm, and 61.20 ppm were confirmed as the δ value of the peak derived from α-type glucose. In addition, 96.79 ppm, 76.70 ppm, 76.59 ppm, 74.78 ppm, 70.30 ppm, and 61.00 ppm were confirmed as δ values of the peak derived from β-type glucose.
[0039]
Next, after saturating carbon dioxide to 8000 parts by mass of a 12% by mass aqueous barium carbonate solution, 330 parts by mass of bromine and 300 parts by mass of glucose obtained above were added thereto, followed by stirring at 25 ° C. for 30 minutes. Thus, 250 parts by mass of gluconolactone represented by the following chemical formula (III) was obtained.
[0040]
Embedded image

When ¹³ C-NMR (100 MHz, DMSO-d ₆ ) of the obtained gluconolactone was measured, the δ value was 171.88 ppm, 81.23 ppm, 73.79 ppm, 71.43 ppm, 67.82 ppm, 60.14 ppm. It was confirmed.
[0041]
250 parts by mass of this gluconolactone and 87 parts by mass of red phosphorus were added to 12,000 parts by mass of hydroiodic acid (55% by mass), and the mixture was heated under reflux for 20 hours. Then, the reaction mixture was filtered, and the filtrate was extracted with ether, and then washed with a 5% aqueous sodium bisulfite solution. Thereafter, ether was distilled off, and the residue was distilled under reduced pressure to obtain 147 parts by mass of caproic acid. When ¹³ C-NMR (100 MHz, CDCl ₃ ) of this caproic acid was measured, it was confirmed that the δ value was 13.90 ppm, 22.42 ppm, 24.51 ppm, 31.36 ppm, 34.22 ppm, 180.79 ppm.
[0042]
N-chlorodiisopropylamine equivalent to 147 parts by mass of the obtained caproic acid was added to 1000 parts by mass of 84% sulfuric acid, and reacted at 25 ° C. for 5 hours to obtain 177 parts by mass of 5-chlorocaproic acid. Thereafter, 177 parts by mass of 5-chlorocaproic acid was boiled with an equivalent amount of an aqueous sodium hydroxide solution to obtain 129 parts by mass of δ-caprolactone. When ¹³ C-NMR (100 MHz, CDCl ₃ ) of the obtained δ-caprolactone was measured, 19.90 ppm, 20.88 ppm, 34.27 ppm, 35.31 ppm, 70.44 ppm and 172.84 ppm were confirmed as δ values. did.
[0043]
129 parts by mass of this δ-caprolactone was heated to 155 ° C. under a nitrogen atmosphere, and 0.39 parts by mass of tri-iso-propoxyaluminum and 0.77 parts by mass of diethylene glycol were added thereto, followed by ring-opening polymerization to obtain an aliphatic polyester. Got. The polymerization time was 10 hours, and the weight average molecular weight of the obtained aliphatic polyester was 290,000.
[0044]
When ¹³ C-NMR (100 MHz, CDCl ₃ ) of the obtained aliphatic polyester was measured, 19.95 ppm, 20.82 ppm, 34.46 ppm, 35.26 ppm, 70.31 ppm, and 173.37 ppm were observed as δ values. Then, it was confirmed that the desired aliphatic polyester was synthesized.
[0045]
(Example 2)
300 parts by mass of glucose obtained in the same manner as in Example 1 were oxidized and hydrolyzed in 2500 parts by mass of 13.5 mol / l sulfuric acid saturated with bromine, and 290 parts by mass of gluconic acid represented by the following chemical formula (IV) Got a part.
[0046]
Embedded image

Next, 290 parts by mass of the obtained gluconic acid and 100 parts by mass of red phosphorus were added to 14000 parts by mass of hydroiodic acid (55% by mass), and the mixture was heated under reflux for 20 hours. Thereafter, the same treatment as in Example 1 was performed to obtain 155 parts by mass of caproic acid.
[0047]
Thereafter, 155 parts by mass of caproic acid and an equivalent amount of N-chlorodiisopropylamine were added to 1000 parts by mass of 84% sulfuric acid, and reacted at 25 ° C. for 5 hours to obtain 187 parts by mass of 5-chlorocaproic acid. 187 parts by mass of this 5-chlorocaproic acid was boiled with an equivalent aqueous sodium hydroxide solution to obtain 136 parts by mass of δ-caprolactone.
[0048]
136 parts by mass of the obtained δ-caprolactone was heated to 160 ° C. under a nitrogen atmosphere, and 0.41 part by mass of di-iso-propyl zinc and 0.82 parts by mass of 1,4-butanediol were added thereto. Ring opening polymerization was performed to obtain an aliphatic polyester. The polymerization time was 10 hours, and the weight average molecular weight of the obtained aliphatic polyester was 220,000. Also, when ¹³ C-NMR was measured, the same spectrum as in Example 1 was obtained, and it was confirmed that the desired aliphatic polyester was synthesized.
[0049]
(Evaluation of the physical properties)
Using the aliphatic polyesters synthesized in Examples 1 and 2, the physical properties shown in Table 1 were evaluated. In addition, as Comparative Example 1, physical properties of Cell Green (manufactured by Daicel Chemical Industries, Ltd., polycaprolactone plastic, P-H7) were also evaluated.
[0050]
[Table 1]

From the above results, each of the aliphatic polyesters synthesized in Examples 1 and 2 was equal to or higher than the aliphatic polyester (P-H7) manufactured by Daicel Chemical and used in Comparative Example 1 and having excellent strength and elongation. It has the above physical properties, and it has been found that it can be sufficiently used as a substitute for a conventional plastic molded product.
[0051]
【The invention's effect】
As described above, the present invention can produce an aliphatic polyester by ring-opening polymerization of δ-caprolactone obtained from starch via glucose, and has sufficient physical properties such as mechanical strength and plasticity. It can be used as a molded product. In addition, this opens the way to the efficient resource utilization of starch by obtaining high-quality plastics starting from starch, which is a substitute for petroleum.

Claims (16)

A method for producing an aliphatic polyester represented by the following formula (I),

(In the formula, n represents an integer of 10 to 6000.)
Hydrolyzing the starch to obtain glucose;
Oxidizing the glucose to obtain gluconolactone;
Reducing the gluconolactone to obtain caproic acid;
Chlorinating the caproic acid to obtain 5-chlorocaproic acid;
Cyclizing the 5-chlorocaproic acid to obtain δ-caprolactone;
A step of subjecting the δ-caprolactone to ring-opening polymerization,
A method for producing an aliphatic polyester, comprising: The method for producing an aliphatic polyester according to claim 1, wherein the step of obtaining glucose from starch is hydrolysis with an acid. 3. The method for producing an aliphatic polyester according to claim 1, wherein the step of obtaining gluconolactone from glucose is bromine oxidation. The method for producing an aliphatic polyester according to any one of claims 1 to 3, wherein the step of obtaining caproic acid from gluconolactone is a reduction reaction using at least hydroiodic acid and red phosphorus. 5. The process for producing an aliphatic polyester according to claim 1, wherein the step of obtaining 5-chlorocaproic acid from caproic acid is a chlorination reaction using at least N-chlorodiisopropylamine and concentrated sulfuric acid. Method. The method for producing an aliphatic polyester according to any one of claims 1 to 5, wherein the step of obtaining δ-caprolactone from 5-chlorocaproic acid is a cyclization reaction using at least an aqueous sodium hydroxide solution. The method for producing an aliphatic polyester according to any one of claims 1 to 6, wherein the step of obtaining the aliphatic polyester from δ-caprolactone is ring-opening polymerization using at least a polymerization catalyst and a polymerization initiator. A method for recycling starch by the method according to any one of claims 1 to 7. A method for producing an aliphatic polyester represented by the following formula (I),

(In the formula, n represents an integer of 10 to 6000.)
Hydrolyzing the starch to obtain glucose;
Oxidizing the glucose to obtain gluconic acid;
Reducing the gluconic acid to obtain caproic acid;
Chlorinating the caproic acid to obtain 5-chlorocaproic acid;
Cyclizing the 5-chlorocaproic acid to obtain δ-caprolactone;
A step of subjecting the δ-caprolactone to ring-opening polymerization,
A method for producing an aliphatic polyester, comprising: The method for producing an aliphatic polyester according to claim 9, wherein the step of obtaining glucose from starch is hydrolysis with an acid. The method for producing an aliphatic polyester according to claim 9 or 10, wherein the step of obtaining gluconic acid from glucose is an oxidation reaction using at least bromine and concentrated sulfuric acid. The method for producing an aliphatic polyester according to any one of claims 9 to 11, wherein the step of obtaining caproic acid from gluconic acid is a reduction reaction using at least hydroiodic acid and red phosphorus. 13. The method for producing an aliphatic polyester according to claim 9, wherein the step of obtaining 5-chlorocaproic acid from caproic acid is a chlorination reaction using at least N-chlorodiisopropylamine and concentrated sulfuric acid. Method. The method for producing an aliphatic polyester according to any one of claims 9 to 13, wherein the step of obtaining δ-caprolactone from 5-chlorocaproic acid is a cyclization reaction using at least an aqueous sodium hydroxide solution. The method for producing an aliphatic polyester according to any one of claims 9 to 14, wherein the step of obtaining the aliphatic polyester from δ-caprolactone is ring-opening polymerization using at least a polymerization catalyst and a polymerization initiator. A method for recycling starch by the method according to any one of claims 9 to 15.