JP4567139B2 - Method for producing alternating copolymer polyester - Google Patents

Description

【００１０】
好ましくは、下記式（２）
【００１１】
【化４】

【００１２】
で表される単位からなり、かつ、フェノール／１,１,２,２−テトラクロロエタン混合溶媒（重量比６／４）を用いて３５℃で測定した極限粘度［η］が０．１〜０．５であるポリエステル（プレポリマー）を結晶化させた後、これを固相重合せしめることにより、極限粘度［η］が０．４〜２．０に高められた交互共重合ポリエステルを得ることを特徴とするポリエステルの製造方法である。
【００１３】
そして、上記の方法において、
ａ）上記式（１）または（２）で表される繰り返し単位から実質的になるポリエステルのプレポリマーを、不活性ガス気流下常圧もしくは１ｍｍＨｇ以下の高真空下にて加熱固相重合することを特徴とする方法、ならびに、
ｂ）固相重合後の上記式（２）で表される繰り返し単位から実質的になる交互共重合ポリエステルの¹Ｈ−ＮＭＲ測定（２３℃、重水素化クロロホルム／重水素化トリフルオロ酢酸＝３／１（ｖ／ｖ）中）において、上記式（１）で表されるポリエステルのメチレンプロトンに由来するシグナルが４．８５ｐｐｍから４．８７ｐｐｍの化学シフトに観測され、このシグナルの積分に対する４．８ｐｐｍ、４．９ｐｐｍ付近の積分の比がそれぞれ０．１以下であることを特徴とする方法、
も、本発明に包含される。
【００１４】
【発明の実施の形態】
本発明方法で用られる比較的低分子量のポリエステル（以下、プレポリマーということがある）は、ポリマー繰り返し単位の少なくとも９０モル％、好ましくは９５モル％以上、より好ましくは９８〜１００モル％が、下記式（１）
【００１５】
【化５】

【００１６】
好ましくは、下記式（２）
【００１７】
【化６】

【００１８】
で表わされるポリエステルであって、ポリマーシークエンスにおいてエチレン−２,６−ナフタレート単位とエチレンテレフタレート単位とが交互に規則正しく配置している線状の共重合体である。
【００１９】
本発明方法で用いられる上記の交互共重合ポリエステルは、テレフタル酸クロライドと２,６−ビス（２'−ヒドロキシエチル）ナフタレートで代表されるヒドロキシアルキル基の炭素数が２〜４の２,６−ビス（２'−ヒドロキアルキル）ナフタレートとを反応させるか、および／または、２,６−ナフタレンジカルボニルクロライドとビス（２−ヒドロキシエチル）テレフタレートで代表されるヒドロキシアルキル基の炭素数が２〜４のビス（２−ヒドロキシアルキル）テレフタレートとを反応させる方法により製造することができる。このような反応は、例えば、Ｎ−メチル−２−ピロリドン等の極性有機溶媒中で上記両成分を反応させる溶液重合法により実施することができる。
【００２０】
上記ポリエステルのプレポリマーの分子量は、フェノール／１,１,２,２−テトラクロロエタン混合溶媒（重量比６／４）を用いて３５℃で測定した極限粘度［η］にして０．１〜０．５であり、好ましくは［η］＝０．２〜０．４である。
【００２１】
このプレポリマーの極限粘度［η］が０．１より低い場合は、後述する結晶化処理を行っても固相重合に供し得る結晶化度のポリマーが得られず、また、極限粘度が［η］が０．５を超えるものは、溶液重合では良好な生産性で製造するのが難しい。
【００２２】
本発明方法では、上述のようにして得られたプレポリマーを平均粒径５ｍｍ以下に粉砕し、これを例えば１２０℃、真空下にて一晩乾燥後、不活性ガス気流下常圧または１ｍｍＨｇ以下の高真空状態でポリマーの結晶化温度（Ｔｃ）以上かつ融点（Ｔｍ）以下の温度にて０．５〜１．０時間かけて加熱することにより結晶化して固相重合用プレポリマーとする。プレポリマーの結晶化手段としては上記の加熱結晶化が好ましいが、必要に応じ、溶媒で処理する方法も採用することができる。
【００２３】
本発明方法では、この結晶化プレポリマーを固相重合槽に供給し、該固相重合槽内で、不活性ガス気流下常圧または１ｍｍＨｇ以下の高真空状態でポリマーのガラス転移温度（Ｔｇ）以上でかつ融点（Ｔｍ）より５〜４０℃低い温度、好適には１５０〜２００℃に加熱して、固相重合せしめることによりポリマーの重合度を高め、最終的には極限粘度［η］が０．４〜２．０、好ましくは０．５〜１．８の高分子量交互共重合ポリエステルとする。この固相重合においては連続的または段階的に温度を上昇させながら加熱するのが好ましい。
【００２４】
固相重合後の上記式（２）で表される繰り返し単位らなる交互共重合ポリエステルの一次構造は、２３℃、重水素化クロロホルム／重水素化トリフルオロ酢酸＝３／１（ｖ／ｖ）中での¹Ｈ−ＮＭＲ測定により明らかにすることができる。例えば、Ｊ．Ｐｏｌｙ．Ｓｃｉ（Ｐａｒｔ Ａ），３４，２８４１（１９９６）には、ＰＥＴとＰＥＮのランダム共重合及びブレンドの¹Ｈ−ＮＭＲ測定による知見が示されており、ＰＥＴとＰＥＮのランダム共重合ではメチレンプロトンに由来するシグナルが３種存在し、それぞれ低磁場側より、２つのテレフタル酸残基とエステル結合したエチレン、一方がテレフタル酸で他方がナフタレンジカルボン酸残基とエステル結合したエチレン、２つのナフタレンジカルボン酸残基とエステル結合したエチレンと帰属されることが報告されている。本発明方法により製造される交互共重合ポリエステルでは、一方がテレフタル酸残基で他方がナフタレンジカルボン酸残基とエステル結合したエチレンのシグナルが主に観測され、固相重合前後においてもこの主なシグナルとランダム共重合に由来する他の２種のシグナルとの面積比が０．１以下、好ましくは０．０５以下、より好ましくは０．０３以下であり、これによって、上記手法を用いた固相重合により交互共重合ポリエステルの一次構造を維持しつつ上記式（１）で表されるポリエステルを高重合度化できる。
【００２５】
【発明の効果】
以上のような本発明の方法により、エステル交換反応によるランダム共重合化を抑制し、かつ、ポリエステルの一次構造を維持しつつ該ポリエステルのプレポリマーより高重合度の交互共重合ポリエステルを安定的に製造することが可能となる。
【００２６】
そして、本発明方法により得られる交互共重合ポリエステルは、ＰＥＴとＰＥＮの利点を併せ持ち、結晶性でかつＴｍ２００℃以上、Ｔｇ９０℃以上の優れた耐熱性を有する素材であり、溶融成型により、機械的性質の良好な繊維・フィルム・成型品などとすることができ、特にボトル用として好適である。そして、これらの成型品においてはＰＥＮの成型品に見られるようなデラミなどの問題は発生しない。
【００２７】
また、このポリエステルは、安定剤、着色剤、紫外線吸収剤、離型剤などの各種添加剤、ガラス繊維などの強化材、さらには無機粒子、有機粒子などの充填材などを添加し樹脂組成物として使用することもできる。
【００２８】
また、この交互共重合ポリエステルは、安定剤、着色剤、紫外線吸収剤、離型剤、難燃剤などの各種添加剤、ガラス繊維や炭素繊維などの強化材、さらには無機微粒子、有機微粒子、他の熱可塑性重合体などの充填材などを添加して樹脂組成物としても有効に使用することができる。
【００２９】
【実施例】
以下、実施例をあげて本発明を説明するが、実施例は説明のためのものであって、本発明はこれに限定されるものではない。なお、例中「部」は特にことわらない限り「重量部」を意味するものとする。
【００３０】
なお、例中に記載した各種の評価項目は次のようにして求めた。
（１）極限粘度［η］の測定
極限粘度［η］はフェノール／１,１,２,２−テトラクロロエタン混合溶液（重量比６／４）中、３５℃にて測定した。
（２）融点、ガラス転移温度の測定
ガラス転移温度（Ｔｇ）、結晶化温度（Ｔｃ）および融点（Ｔｍ）の測定は、セイコーＤＳＣ２２０示差走査熱量計を用い、窒素ガス気流下、１０℃／ｍｉｎの速度で昇温して測定を行った。
（３）¹Ｈ−ＮＭＲ測定
¹Ｈ−ＮＭＲ測定は日本電子ＪＮＲ−ＥＸ２７０を用い、重水素化クロロホルム／重水素化トリフルオロ酢酸＝３／１（ｖ／ｖ）混合溶媒中２３℃にて測定を行った。
【００３１】
［参考例１］
室温、窒素気流下にてビス（２−ヒドロキシエチル）テレフタレート５．０１部を乾燥ピリジン３．４ｍｌと乾燥Ｎ−メチル−２−ピロリドン５０ｍｌとの混合物に溶解し、これに２,６−ナフタレンジカルボニルクロライド４．９９部の乾燥Ｎ−メチル−２−ピロリドン６０ｍｌに溶解した溶液を滴下し、室温で０．５時間攪拌した。４０℃で０．５時間、８０℃で１．５時間、１００℃で１．５時間加熱攪拌したのちに反応溶液を室温まで冷却し、これを水３Ｌに注いで析出した白色固体を濾別した。これを水５００ｍｌ、アセトン３００ｍｌで洗浄したのちに１２０℃で真空乾燥してポリマー８．０部（収率９４％）を得た。
このポリマーは［η］＝０．２１、Ｔｇ＝１０４℃、Ｔｃ＝１５０℃、Ｔｍ＝２２１℃であり、Ｘ線回折および¹Ｈ−ＮＭＲ測定により上記式（２）の繰り返し単位からなるポリエステルであることを確認した。
った。
【００３２】
［参考例２］
室温、窒素気流下にて２,６−ビス（２'−ヒドロキシエチル）ナフタレート３５．９８部を乾燥ピリジン２０．０ｍｌ、乾燥Ｎ−メチル−２−ピロリドン８０ｍｌに溶解し、これにテレフタル酸クロライド２４．０２部の乾燥Ｎ−メチル−２−ピロリドン２６０ｍｌに溶解した溶液を滴下し、室温で１．０時間攪拌した。６０℃で１．５時間加熱攪拌したのちに反応溶液を室温まで冷却し、これを水５Ｌに注いで析出した白色固体を濾別した。水１Ｌ、アセトン５００ｍｌで洗浄後、１２０℃で真空乾燥してポリマー４９．３部（収率９６％）を得た。
このポリマーは［η］＝０．２４、Ｔｇ＝１０４℃、Ｔｃ＝１５６℃、Ｔｍ＝２２５℃であり、Ｘ線回折および¹Ｈ−ＮＭＲ測定により上記式（２）の繰り返し単位からなるポリエステルであることを確認した。
【００３３】
［実施例１］
参考例１で得られた［η］＝０．２１のポリエステル（プレポリマー）を粒径５ｍｍ以下に粉砕後、１７０℃で高真空下にて１時間加熱結晶化させて、固相重合用プレポリマーとした。この結晶化プレポリマー６．５部を固相重合釜に入れ、高真空下にて、１９０℃で３時間、次いで１９５℃で７時間、さらに２００℃で１２時間加熱して固相重合を行った。固相重合後のポリマーは［η］＝０．５０、Ｔｇ＝１０４℃、Ｔｍ＝２１３℃であった。この実施例１の固相重合におけるポリマーの［η］の経時変化を図１に実線で示す。
【００３４】
［実施例２］
参考例２で得られた［η］＝０．２４のポリエステル（プレポリマー）を粒径５ｍｍ以下に粉砕後、１７０℃で高真空下にて１時間加熱結晶化させて、固相重合用プレポリマーとした。この結晶化プレポリマー４５．０部を固相重合釜に入れ、高真空下にて１９０℃で３９時間加熱して固相重合を行った。固相重合後のポリマーは［η］＝０．４６、Ｔｇ＝１０３℃、Ｔｃ＝１９０℃、Ｔｍ＝２１７℃であった。この実施例２の固相重合におけるポリマー［η］の経時変化を図１に破線で示す。
【００３５】
［実施例３］
実施例１および実施例２で得られた各ポリマーを、重水素化クロロホルム／重水素化トリフルオロ酢酸＝３／１（ｖ／ｖ）混合溶媒中２３℃にて¹Ｈ−ＮＭＲ測定を行い、４．７〜４．９ｐｐｍに観測されるメチレンプロトンに由来するシグナルについて固相重合前後の変化を追跡した。
【００３６】
ランダム共重合では低磁場側より２つのテレフタル酸残基とエステル結合したエチレン、一方がテレフタル酸で他方がナフタレンジカルボン酸残基とエステル結合したエチレン、２つのナフタレンジカルボン酸残基とエステル結合したエチレンと３種のシグナルが帰属されるが、それぞれの積分比をｘ、ｙ、ｚとしてｘ／ｙ、ｚ／ｙの値を算出したところ、実施例１，２ともに固相重合後のｘ／ｙ、ｚ／ｙの値は０．０５以下であり、固相重合反応においてポリエステルの一次構造が維持されていることが明らかとなった。算出したｘ／ｙ、ｚ／ｙの値を次の表１に示す。
【００３７】
【表１】

【図面の簡単な説明】
【図１】図１は、固相重合（実施例１，２）における上記交互共重合ポリエステルの極限粘度［η］の経時変化を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a high-molecular-weight alternating copolymer polyester having an intrinsic viscosity [η] of 0.4 to 2.0 while maintaining the primary structure of the alternating copolymer polyester.
[0002]
[Prior art]
Polyesters represented by PET (polyethylene terephthalate) and PEN (polyethylene-2,6-naphthalate) have excellent mechanical, physical, and chemical properties, so other moldings such as clothing and industrial fibers are used. Widely used for things.
[0003]
However, a molded article of PEN having excellent mechanical properties and heat resistance has low impact resistance and delamination, and PET having a Tg of 70 ° C. has low heat resistance.
[0004]
As a technique for improving this, a method of copolymerizing polyesters such as PEN and PET by melt polymerization is conventionally known. However, it is generally known that in this method, the primary structure of the polyester copolymer is randomized because the copolymer is a polycondensation accompanied by a transesterification reaction. Therefore, the crystallinity and melting point inherent to PET and PEN are remarkably lowered, and as a result, the heat resistance and mechanical properties of the molded product become insufficient.
[0005]
For this reason, the present inventors have previously proposed a novel alternating copolymer and a method for producing the copolymer by solution polymerization (Japanese Patent Application No. 2000-90776). However, it is difficult to obtain an alternating copolymer having a sufficient degree of polymerization as a molding material while maintaining the primary structure of the alternating copolymer polyester only by solution polymerization.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a crystalline alternating copolymer having a sufficient degree of polymerization as a molding material while maintaining the primary structure of the alternating copolymer polyester without causing random copolymerization of the polyester copolymer by transesterification. The object is to provide a method suitable for producing polyester.
[0007]
[Means for Solving the Problems]
As a result of intensive studies in order to solve the above problems, the present inventors have produced a polyester prepolymer represented by the above formula (1) and solid-phase polymerized it, thereby transesterification reaction. It has been found that it is possible to produce a polyester having a sufficient degree of polymerization as a molding material while maintaining the primary structure of the polyester represented by the above formula (1) without causing random copolymerization of the polyester copolymer. The present invention has been completed.
[0008]
That is, the present invention
At least 90 mol% of the polymer repeating unit is represented by the following formula (1)
[0009]
[Chemical 3]

[0010]
Preferably, the following formula (2)
[0011]
[Formula 4]

[0012]
The intrinsic viscosity [η] measured at 35 ° C. using a phenol / 1,1,2,2-tetrachloroethane mixed solvent (weight ratio 6/4) is 0.1-0. The polyester (prepolymer) of .5 is crystallized and then solid-phase polymerized to obtain an alternating copolymer polyester having an intrinsic viscosity [η] increased to 0.4 to 2.0. It is the manufacturing method of the polyester characterized.
[0013]
And in the above method,
a) Solid phase polymerization of a polyester prepolymer substantially consisting of the repeating unit represented by the above formula (1) or (2) under normal pressure under an inert gas stream or under a high vacuum of 1 mmHg or less. And a method characterized by
b) ¹ H-NMR measurement (23 ° C., deuterated chloroform / deuterated trifluoroacetic acid = 3) of the alternating copolymerized polyester substantially consisting of the repeating unit represented by the above formula (2) after solid phase polymerization / 1 (in v / v)), a signal derived from the methylene proton of the polyester represented by the above formula (1) was observed at a chemical shift of 4.85 ppm to 4.87 ppm. A method in which the ratios of integrals in the vicinity of 8 ppm and 4.9 ppm are each 0.1 or less,
Are also encompassed by the present invention.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The relatively low molecular weight polyester (hereinafter sometimes referred to as prepolymer) used in the method of the present invention is at least 90 mol%, preferably 95 mol% or more, more preferably 98 to 100 mol% of the polymer repeating unit. Following formula (1)
[0015]
[Chemical formula 5]

[0016]
Preferably, the following formula (2)
[0017]
[Chemical 6]

[0018]
Is a linear copolymer in which ethylene-2,6-naphthalate units and ethylene terephthalate units are regularly and alternately arranged in a polymer sequence.
[0019]
The above alternating copolymerized polyester used in the method of the present invention is a 2,6-carbon compound having a hydroxyalkyl group represented by terephthalic acid chloride and 2,6-bis (2′-hydroxyethyl) naphthalate having 2 to 4 carbon atoms. Bis (2′-hydroxyalkyl) naphthalate is reacted and / or the hydroxyalkyl group represented by 2,6-naphthalenedicarbonyl chloride and bis (2-hydroxyethyl) terephthalate has 2 to 4 carbon atoms. The bis (2-hydroxyalkyl) terephthalate can be produced by a reaction method. Such a reaction can be carried out, for example, by a solution polymerization method in which the two components are reacted in a polar organic solvent such as N-methyl-2-pyrrolidone.
[0020]
The molecular weight of the polyester prepolymer is 0.1 to 0 in terms of intrinsic viscosity [η] measured at 35 ° C. using a phenol / 1,1,2,2-tetrachloroethane mixed solvent (weight ratio 6/4). 0.5, and preferably [η] = 0.2 to 0.4.
[0021]
When the intrinsic viscosity [η] of this prepolymer is lower than 0.1, a polymer having a degree of crystallinity that can be used for solid phase polymerization cannot be obtained even if the crystallization treatment described later is performed, and the intrinsic viscosity is [η ] Exceeding 0.5 is difficult to produce with good productivity in solution polymerization.
[0022]
In the method of the present invention, the prepolymer obtained as described above is pulverized to an average particle size of 5 mm or less, and this is dried at 120 ° C. under vacuum overnight, for example, at atmospheric pressure under an inert gas stream or 1 mmHg or less. In a high vacuum state, the polymer is crystallized by heating at a temperature not lower than the crystallization temperature (Tc) of the polymer and not higher than the melting point (Tm) for 0.5 to 1.0 hour to obtain a prepolymer for solid phase polymerization. As the prepolymer crystallization means, the above-mentioned heat crystallization is preferable, but a method of treating with a solvent can also be adopted if necessary.
[0023]
In the method of the present invention, this crystallized prepolymer is supplied to a solid phase polymerization vessel, and the glass transition temperature (Tg) of the polymer in the solid phase polymerization vessel at normal pressure under an inert gas stream or in a high vacuum state of 1 mmHg or less. The polymerization degree of the polymer is increased by heating to a temperature lower than the melting point (Tm) by 5 to 40 ° C., preferably 150 to 200 ° C., and solid-phase polymerization, and finally the intrinsic viscosity [η] is A high molecular weight alternating copolymer polyester of 0.4 to 2.0, preferably 0.5 to 1.8 is used. In this solid-state polymerization, it is preferable to heat while increasing the temperature continuously or stepwise.
[0024]
The primary structure of the alternating copolymer polyester comprising the repeating unit represented by the above formula (2) after the solid phase polymerization is 23 ° C., deuterated chloroform / deuterated trifluoroacetic acid = 3/1 (v / v). It can be clarified by ¹ H-NMR measurement in the medium. For example, J. et al. Poly. Sci (Part A), 34 , 2841 (1996) shows the knowledge of random copolymerization of PET and PEN and ¹ H-NMR measurement of the blend. In random copolymerization of PET and PEN, it is derived from methylene protons. There are three kinds of signals, each from low magnetic field side, ethylene that is ester-linked with two terephthalic acid residues, one that is terephthalic acid and the other is ester-linked with naphthalenedicarboxylic acid residues, and two naphthalenedicarboxylic acid residues It is reported to be attributed to ethylene ester-linked to the group. In the alternating copolymer polyester produced by the method of the present invention, the ethylene signal in which one is a terephthalic acid residue and the other is an ester bond with a naphthalenedicarboxylic acid residue is mainly observed. And the area ratio of the other two signals derived from random copolymerization is 0.1 or less, preferably 0.05 or less, more preferably 0.03 or less. The degree of polymerization of the polyester represented by the above formula (1) can be increased while maintaining the primary structure of the alternating copolymer polyester by polymerization.
[0025]
【The invention's effect】
By the method of the present invention as described above, random copolymerization by transesterification reaction is suppressed, and an alternating copolymer polyester having a higher degree of polymerization than a prepolymer of the polyester can be stably stabilized while maintaining the primary structure of the polyester. It can be manufactured.
[0026]
The alternating copolymer polyester obtained by the method of the present invention has the advantages of PET and PEN, is a crystalline material with excellent heat resistance of Tm 200 ° C. or higher, Tg 90 ° C. or higher, and is mechanically melt-molded. It can be made into a fiber, a film, a molded product, etc. with good properties, and is particularly suitable for bottles. In these molded products, problems such as delamination as seen in PEN molded products do not occur.
[0027]
In addition, this polyester is added with various additives such as stabilizers, colorants, ultraviolet absorbers, release agents, reinforcing materials such as glass fibers, and fillers such as inorganic particles and organic particles. It can also be used as
[0028]
In addition, this alternating copolymer polyester can be used for various additives such as stabilizers, colorants, UV absorbers, mold release agents, flame retardants, reinforcing materials such as glass fibers and carbon fibers, inorganic fine particles, organic fine particles, etc. It can be used effectively as a resin composition by adding a filler such as a thermoplastic polymer.
[0029]
【Example】
Hereinafter, the present invention will be described with reference to examples. However, the examples are for illustrative purposes and the present invention is not limited thereto. In the examples, “parts” means “parts by weight” unless otherwise specified.
[0030]
Various evaluation items described in the examples were obtained as follows.
(1) Measurement of intrinsic viscosity [η] The intrinsic viscosity [η] was measured at 35 ° C. in a phenol / 1,1,2,2-tetrachloroethane mixed solution (weight ratio 6/4).
(2) Measurement of melting point and glass transition temperature Glass transition temperature (Tg), crystallization temperature (Tc) and melting point (Tm) were measured using a Seiko DSC220 differential scanning calorimeter at 10 ° C./min under a nitrogen gas stream. The temperature was increased at a rate of
(3) ¹ H-NMR measurement
¹ H-NMR measurement was performed using JEOL JNR-EX270 at 23 ° C. in a deuterated chloroform / deuterated trifluoroacetic acid = 3/1 (v / v) mixed solvent.
[0031]
[Reference Example 1]
Under a nitrogen stream at room temperature, 5.01 parts of bis (2-hydroxyethyl) terephthalate was dissolved in a mixture of 3.4 ml of dry pyridine and 50 ml of dry N-methyl-2-pyrrolidone, and 2,6-naphthalene was added thereto. A solution dissolved in 4.99 parts of carbonyl chloride in 60 ml of dry N-methyl-2-pyrrolidone was added dropwise and stirred at room temperature for 0.5 hour. After stirring with heating at 40 ° C. for 0.5 hours, at 80 ° C. for 1.5 hours, and at 100 ° C. for 1.5 hours, the reaction solution was cooled to room temperature, poured into 3 L of water, and the precipitated white solid was filtered off. did. This was washed with 500 ml of water and 300 ml of acetone and then vacuum-dried at 120 ° C. to obtain 8.0 parts of polymer (yield 94%).
This polymer has [η] = 0.21, Tg = 104 ° C., Tc = 150 ° C., Tm = 221 ° C., and is a polyester comprising repeating units of the above formula (2) by X-ray diffraction and ¹ H-NMR measurement. I confirmed that there was.
It was.
[0032]
[Reference Example 2]
Under a nitrogen stream at room temperature, 35.98 parts of 2,6-bis (2′-hydroxyethyl) naphthalate was dissolved in 20.0 ml of dry pyridine and 80 ml of dry N-methyl-2-pyrrolidone. A solution dissolved in .02 parts of dry N-methyl-2-pyrrolidone (260 ml) was added dropwise and stirred at room temperature for 1.0 hour. After stirring with heating at 60 ° C. for 1.5 hours, the reaction solution was cooled to room temperature, poured into 5 L of water, and the precipitated white solid was filtered off. After washing with 1 L of water and 500 ml of acetone, it was vacuum dried at 120 ° C. to obtain 49.3 parts of polymer (yield 96%).
This polymer is [η] = 0.24, Tg = 104 ° C., Tc = 156 ° C., Tm = 225 ° C., and is a polyester comprising repeating units of the above formula (2) by X-ray diffraction and ¹ H-NMR measurement. I confirmed that there was.
[0033]
[Example 1]
After the polyester (prepolymer) of [η] = 0.21 obtained in Reference Example 1 was pulverized to a particle size of 5 mm or less, it was heated and crystallized at 170 ° C. under a high vacuum for 1 hour to obtain a solid phase polymerization pre A polymer was obtained. 6.5 parts of this crystallized prepolymer is placed in a solid phase polymerization kettle and heated under high vacuum at 190 ° C. for 3 hours, then at 195 ° C. for 7 hours, and further at 200 ° C. for 12 hours for solid phase polymerization It was. The polymer after the solid phase polymerization had [η] = 0.50, Tg = 104 ° C., and Tm = 213 ° C. The time-dependent change in [η] of the polymer in the solid phase polymerization of Example 1 is shown by a solid line in FIG.
[0034]
[Example 2]
After the polyester (prepolymer) of [η] = 0.24 obtained in Reference Example 2 is pulverized to a particle size of 5 mm or less, it is heated and crystallized at 170 ° C. under a high vacuum for 1 hour to obtain a solid phase polymerization pre-polymer. A polymer was obtained. 45.0 parts of this crystallized prepolymer was placed in a solid phase polymerization kettle and heated at 190 ° C. for 39 hours under high vacuum to carry out solid phase polymerization. The polymer after the solid phase polymerization had [η] = 0.46, Tg = 103 ° C., Tc = 190 ° C., Tm = 217 ° C. The time-dependent change of the polymer [η] in the solid phase polymerization of Example 2 is shown by a broken line in FIG.
[0035]
[Example 3]
Each polymer obtained in Example 1 and Example 2 was subjected to ¹ H-NMR measurement at 23 ° C. in a deuterated chloroform / deuterated trifluoroacetic acid = 3/1 (v / v) mixed solvent, Changes before and after solid-state polymerization were followed for signals derived from methylene protons observed at 4.7 to 4.9 ppm.
[0036]
In random copolymerization, ethylene is ester-linked with two terephthalic acid residues from the low magnetic field side, one is terephthalic acid and the other is ester-linked ethylene with naphthalenedicarboxylic acid residue, and two is naphthalenedicarboxylic acid residue is ester-linked ethylene And three types of signals are assigned, and the values of x / y and z / y were calculated with x, y and z as their integral ratios. Z / y was 0.05 or less, and it was revealed that the primary structure of the polyester was maintained in the solid phase polymerization reaction. The calculated values of x / y and z / y are shown in Table 1 below.
[0037]
[Table 1]

[Brief description of the drawings]
FIG. 1 is a graph showing the change over time in the intrinsic viscosity [η] of the alternating copolymer polyester in solid phase polymerization (Examples 1 and 2).

Claims (4)

At least 90 mol% of the polymer repeating unit is represented by the following formula (1)

And an intrinsic viscosity [η] measured at 35 ° C. using a phenol / 1,1,2,2-tetrachloroethane mixed solvent (weight ratio 6/4) is 0.1 to 0. .5 polyester is crystallized and then solid-phase polymerized to obtain an alternating copolymer polyester having an intrinsic viscosity [η] increased to 0.4 to 2.0. A method for producing polyester. In the polyester, at least 90 mol% of the polymer repeating unit is represented by the following formula (2).

The method for producing a polyester according to claim 1, wherein the polymer comprises a unit represented by: The method for producing a polyester according to claim 1 or 2, wherein the polyester is heated and solid-phase polymerized at normal pressure under an inert gas stream or under a high vacuum of 1 mmHg or less. In the ¹ H-NMR measurement (at 23 ° C. in deuterated chloroform / deuterated trifluoroacetic acid = 3/1 (v / v)) of the alternating copolymerized polyester after solid-phase polymerization, it is represented by the above formula ( 2 ). A signal derived from the methylene protons of the obtained polyester is observed at a chemical shift of 4.85 ppm to 4.87 ppm, and the ratio of the integrals around 4.8 ppm and 4.9 ppm to the integral of this signal is 0.1 or less, respectively. The method for producing a polyester according to claim 2, wherein:

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