JP3697752B2 - Method for producing liquid crystal polymer - Google Patents

Description

（ただし式中のＲ₁ は
【化５】

から選ばれた一種以上の基を示し、Ｒ₂ は
【化６】

から選ばれた一種以上の基を示す。また、式中Ｘは水素原子または塩素原子を示し、構造単位［（II）＋（III ）］と構造単位（IV）は実質的に等モルである）。
【００１０】
本発明で言う撹拌翼は、中心軸を有しないフレームに取り付けられたヘリカルリボン翼、およびボトム翼からなるものである。中心軸を有しないフレームに取り付けられたヘリカルリボン翼とは、ヘリカルリボン翼が中心軸と直角の固定棒に取り付けられておらず、缶壁面沿いの垂直なフレームに取り付けられているものであり、缶壁面からの距離が缶直径の０．２以内に位置する２本以上のフレームが好ましく用いられる。ボトム翼の形状としてはいかり型やリボン型などが好ましく用いられる。また、缶壁面と翼のクリアランスが２０ｍｍ以下の範囲であることが好ましい。この撹拌翼は中心軸を有さないため、撹拌翼へのポリマー付着量が少なく缶残ポリマーが減少することのみならず、中心軸近傍の異常滞留部がないのでポリマーが均一に撹拌され缶内温度分布が小さく均質な液晶ポリマーが得られる。また、撹拌翼へのポリマー付着量を抑制する点で、撹拌により缶壁面の液が下がる、掻き下げ方向に撹拌することが好ましい。さらに、均一な撹拌を達成するため内容物の量を撹拌翼上段までの容量の５０％〜９０％にコントロールすることも好ましく行われる。
【００１１】
本発明に用いるポリエステル用竪型反応装置はアセチル化反応と重縮合反応が別々に行える２個以上の反応缶を有する装置が好ましく、さらに反応缶の縦の長さと横の長さの比が１より大きく３未満の形状のものが好ましい。
【００１２】
本発明の液晶ポリマーは溶融時異方性を形成し得るポリマーであり、前記（Ｉ）、（II）、（III ）、（IV）の構造単位からなる液晶ポリエステルである。上記構造単位（Ｉ）はｐ−ヒドロキシ安息香酸から生成したポリエステルの構造単位であり、構造単位（II）は４，４’−ジヒドロキシビフェニル、３，３’，５，５´−テトラメチル−４，４´−ジヒドロキシビフェニル、ハイドロキノン、ｔ−ブチルハイドロキノン、フェニルハイドロキノン、２，６−ジヒドロキシナフタレン、２，７−ジヒドロキシナフタレン、２，２−ビス（４−ヒドロキシフェニル）プロパンおよび４，４´−ジヒドロキシジフェニルエーテルから選ばれた芳香族ジヒドロキシ化合物から生成した構造単位を、構造単位（III ）はエチレングリコールから生成した構造単位を、構造単位（IV）はテレフタル酸、イソフタル酸、４，４´−ジフェニルジカルボン酸、２，６−ナフタレンジカルボン酸、１，２−ビス（フェノキシ）エタン−４，４´−ジカルボン酸、１，２−ビス（２−クロルフェノキシ）エタン−４，４´−ジカルボン酸およびジフェニルエーテルジカルボン酸から選ばれた芳香族ジカルボン酸から生成した構造単位を各々示す。これらのうち特にＲ₁ が
【化７】

であるものが構造単位（II）の７０モル％以上を、Ｒ₂ が
【化８】

であるものが構造単位（IV）の７０モル％以上を占めるものが特に好ましい。
【００１３】
上記構造単位（Ｉ）、（II）、（III ）、（IV）の共重合量は任意である。しかし、流動性の点から次の共重合量であることが好ましい。
【００１４】
すなわち、耐熱性、難燃性および機械的特性の点から上記構造単位［（Ｉ）＋（II）］は［（Ｉ）＋（II）＋（III ）］の６０〜９５モル％が好ましく、８２〜９３モル％がより好ましい。また、構造単位（III ）は［（Ｉ）＋（II）＋（III ）］の４０〜５モル％が好ましく、１８〜７モル％がより好ましい。また、構造単位（Ｉ）／（II）のモル比は耐熱性と流動性のバランスの点から好ましくは７５／２５〜９５／５であり、より好ましくは７８／２２〜９３／７である。また、構造単位（IV）は構造単位［（II）＋（III ）］と実質的に等モルである。
【００１５】
なお、上記ポリエステルを重縮合する際には上記構造単位（Ｉ）〜（IV）を構成する成分以外に３，３´−ジフェニルジカルボン酸、２，２´−ジフェニルジカルボン酸などの芳香族ジカルボン酸、アジピン酸、アゼライン酸、セバシン酸、ドデカンジオン酸などの脂肪族ジカルボン酸、ヘキサヒドロテレフタル酸などの脂環式ジカルボン酸、クロルハイドロキノン、メチルハイドロキノン、４，４´−ジヒドロキシジフェニルスルホン、４，４´−ジヒドロキシジフェニルスルフィド、４，４´−ジヒドロキシベンゾフェノン等の芳香族ジオール、１，４−ブタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコール、１，４−シクロヘキサンジオール、１，４−シクロヘキサンジメタノール等の脂肪族、脂環式ジオールおよびｍ−ヒドロキシ安息香酸、２，６−ヒドロキシナフトエ酸などの芳香族ヒドロキシカルボン酸およびｐ−アミノフェノール、ｐ−アミノ安息香酸などを本発明の目的を損なわない程度の少割合の範囲でさらに共重合せしめることができる。
【００１６】
なお本発明において、液晶ポリマーを重合して製造する方法としては特に制限はなく、例えば液晶ポリエステルを脱酢酸重合を行なうことにより製造することができる。具体的には（１）または（２）の方法があるが（２）の方法が特に好ましい。
【００１７】
（１）ｐ−アセトキシ安息香酸および４，４´−ジアセトキシビフェニル、パラジアセトキシベンゼンなどの芳香族ジヒドロキシ化合物のジアシル化物とテレフタル酸などの芳香族ジカルボン酸、エチレングリコ−ルと芳香族ジカルボン酸からのポリエステルやオリゴマあるいは芳香族ジカルボン酸のビス（β−ヒドロキシエチル）エステルとを脱酢酸重縮合反応によって製造する方法。
【００１８】
（２）ｐ−ヒドロキシ安息香酸、４，４´−ジヒドロキシビフェニル、ハイドロキノンなどの芳香族ジヒドロキシ化合物、無水酢酸、テレフタル酸などの芳香族ジカルボン酸およびエチレングリコ−ルと芳香族ジカルボン酸からのポリエステルやオリゴマあるいは芳香族ジカルボン酸のビス（β−ヒドロキシエチル）エステルとを反応させてフェノール性水酸基をアシル化した後、脱酢酸重縮合反応によって製造する方法。
【００１９】
この脱酢酸反応は無触媒系で行っても重合は進行するが、酢酸第一錫、テトラブチルチタネート、酢酸カリウム、三酸化アンチモン、マグネシウム、酢酸ナトリウムなどの金属化合物を触媒として添加した方が好ましい場合もある。
【００２０】
本発明で製造する液晶ポリマーは、ペンタフルオロフェノール中で対数粘度を測定することが可能なものもあり、その際には０．１ｇ／ｄｌの濃度で６０℃で測定した値で０．３ｄｌ／ｇ以上が好ましく、０．５〜３．０ｄｌ／ｇが特に好ましい。
【００２１】
また、本発明における液晶ポリマーの溶融粘度は１０〜２０，０００ポイズが好ましく、特に２０〜１０，０００ポイズがより好ましい。
【００２２】
なお、この溶融粘度は融点（Ｔｍ）＋１０℃の条件で、ずり速度１，０００（１／秒）の条件下で効果式フローテスターによって測定した値である。
【００２３】
ここで、融点（Ｔｍ）とは示差走査熱量計において、重合を完了したポリマーを室温から２０℃／分の昇温条件で測定した際に観測される吸熱ピーク温度（Ｔｍ１）の観測後、Ｔｍ１＋２０℃の温度で５分間保持した後、２０℃／分の降温条件で室温まで一旦冷却した後、再度２０℃／分の昇温条件で測定した際に観測される吸熱ピーク温度（Ｔｍ２）を指す。
【００２４】
かくして得られる液晶ポリエステルは良好な光学異方性、機械的性質および耐熱性を示し、通常の射出成形に供することができ、３次元成形品などに射出成形することが可能である。 また、本発明で得られる液晶ポリエステルに対して、ガラス繊維、炭素繊維、芳香族ポリアラミド繊維、チタン酸カリウム繊維、石膏繊維、セラミック繊維、ボロンウイスカ繊維、マイカ、シリカ、炭酸カルシュウム、ガラスビーズ、ガラスフレーク、クレー、ワラステナイト、酸化チタン、グラファイトなどの繊維状、粒状、粉状あるいは板状の無機フィラーなどの強化材、酸化防止剤、熱安定剤、難燃剤、紫外線吸収剤、滑剤、離型剤、染料および顔料などの通常の添加剤や他の熱可塑性樹脂を添加して、所望の特性を付与することができる。
【００２５】
【実施例】
以下、実施例により本発明をさらに詳述する。
【００２６】
実施例１
縦と横の比が２．５の内容積０．１ｍ³ のエステル交換用の反応缶Ａと重縮合用の反応缶Ｂの２缶を使い、次のように重合した。
【００２７】
図１は重縮合用の反応缶Ｂに用いたポリエステル用竪型反応装置の断面図である。反応缶６内において撹拌翼は缶壁面からの距離が缶直径の０．１２の位置に設けた２本のフレーム３で支持されたヘリカルリボン翼４とボトム翼５からなる。回転方向は掻き下げ方向で使用した。
【００２８】
反応缶Ａにｐ−ヒドロキシ安息香酸２２．１ｋｇ、４，４’−ジヒドロキシビフェニル２．８ｋｇ、ポリエチレンテレフタレ−ト４．８ｋｇ，テレフタル酸２．５ｋｇおよび無水酢酸２１．７ｋｇを仕込（撹拌翼最上段までの容積の６５％に相当）、１３０℃〜２５０℃で５時間エステル化反応を行い、その後反応缶Ｂに移液して、２時間かけて２５０℃〜３１５℃にし、反応缶Ｂを１Ｔｏｒｒまで減圧し、３１５℃で２時間撹拌を続け重縮合反応を完了した。その後缶内を４ｋｇ／ｃｍ² に加圧後口金を経由してポリマをストランド状に吐出してペレット化し、９５％の収率でペレットを得た。このポリマの対数粘度は１．９６ｄｌ／ｇ、溶融粘度は９００ポイズであった。この時の缶残ポリマー量は１．０ｋｇ（重合缶内容積当り１０ｋｇ／ｍ³ ）であった。このポリマーの理論構造式を下記する。
【００２９】
【化９】

ｋ／ｌ／ｍ／ｎ＝８０／７．５／１２．５／２０
吐出終了後反応缶Ｂのルッキンググラスから缶内を観察したところ、ヘリカルリボン翼４とボトム翼５からなる撹拌翼には殆どポリマーが付着していないことが分かった。
【００３０】
次に得られたペレットを１５０℃で１昼夜乾燥後、住友ネスタール射出成形機プロマット（住友重機械工業（株）製）に供し、シリンダー温度３２０℃で成形機内滞留時間１０分後に試験片（１／８”×１／２”×５”）を成形した。なお、１０分滞留後２ショット分パージしたがパージポリマは発泡もなく正常であった。歪速度１０ｍｍ分、スパン間距離５０ｍｍでの曲げ試験の結果、曲げ強度１４２ＭＰａ、曲げ弾性率１０．８ＧＰａであった。
【００３１】
比較例１
重縮合用の反応缶Ｂとして、中心軸を有し、それに直角の３本の固定棒に取り付けられたヘリカルリボン翼を使用し、実施例１と同様に重縮合反応を行い吐出、ペレット化した。収率は９０％と実施例１より低かった。また缶残ポリマー量は２．０ｋｇ（重合缶容積当り２０ｋｇ／ｍ³ ）で実施例１よりも多かった。実施例１と同様にルッキングラスから缶内を観察したところヘリカルリボン翼に多量のポリマーが付着していることが分かった。
【００３２】
さらに、実施例１同様に成形機に１０分間滞留させて２ショットパージしたところポリマが発泡していた。その後実施例１と同様成形し試験した結果、曲げ強度１３２ＭＰａ、曲げ弾性率９．３ＧＰａであった。
【００３３】
【発明の効果】
本発明によればポリマー収率が良好で熱安定性に優れた均質な液晶性ポリエステルが得られる。
【図面の簡単な説明】
【図１】図１は実施例１で用いたポリエステル用竪型反応装置の断面図である。
【符号の説明】
１：撹拌軸、２：蒸気出口、３：フレーム、４：ヘリカルリボン翼、５：ボトム翼、６：反応缶[0001]
[Industrial application fields]
The present invention relates to a method for producing a liquid crystal polymer. More specifically, the present invention relates to a method for producing a liquid crystal polymer having high quality, particularly heat stability during molding processing, by performing efficient stirring in a melt polycondensation reaction.
[0002]
[Prior art]
In recent years, there has been an increasing demand for higher performance of plastics, and many polymers having various new performances have been developed and put on the market. Among them, optically anisotropic liquid crystal polymers characterized by parallel arrangement of molecular chains are attracting attention because of their excellent fluidity and mechanical properties, and their applications are expanding to mechanical parts, electrical and electronic parts. .
[0003]
As a method for producing a liquid crystal polymer, as disclosed in JP-A-1-149825, when the viscosity increases, the number of stirring is decreased and the polymerization reaction temperature is controlled, or disclosed in JP-A-4-22502. It is known to use a vertical reactor equipped with helical ribbon blades as described above.
[0004]
[Problems to be solved by the invention]
However, it has been found that a stirring blade having a central axis represented by a conventional helical ribbon blade has a problem that a large amount of polymer adheres around the central axis of the stirring blade and a large amount of residual polymer remains. Moreover, mixing during polymerization is not always sufficient, and a component with a low polymerization degree is included, and problems such as gasification and foaming of this component due to retention during molding processing cannot be completely solved, and high quality is achieved. It turns out that it is not necessarily sufficient to expand into the fields of required electrical and electronic parts. Therefore, the present invention is to provide a method for producing a homogeneous liquid crystal polymer having a small amount of residual polymer and having excellent thermal stability.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention provides (1) a helical attached to a frame that does not have a central axis in the production of a liquid crystal polymer comprising the following structural units (I), ( II ), ( III ), and ( IV ). A method for producing a liquid crystal polymer, wherein polymerization is performed using a vertical reactor equipped with a stirring blade composed of a ribbon blade and a bottom blade.
[0006]
(2) The method for producing a liquid crystal polymer, wherein the frame to which the helical ribbon wing is attached is two or more frames located within 0.2 of the can diameter as a distance from the can wall surface.
[0008]
( 3 ) The method for producing a liquid crystal polymer according to item (1), wherein the stirring direction of the stirring blade is a direction in which the reactant is scraped down.
[0009]
[Formula 4]

(However, R ₁ in the formula is:

And at least one group selected from R ₂ is

One or more groups selected from In the formula, X represents a hydrogen atom or a chlorine atom, and the structural unit [(II) + (III)] and the structural unit (IV) are substantially equimolar).
[0010]
The stirring blade referred to in the present invention is composed of a helical ribbon blade attached to a frame having no central axis, and a bottom blade. A helical ribbon wing attached to a frame that does not have a central axis means that the helical ribbon wing is not attached to a fixed rod perpendicular to the central axis, and is attached to a vertical frame along the can wall surface, Two or more frames whose distance from the can wall surface is within 0.2 of the can diameter are preferably used. As the shape of the bottom wing, an anchor type or a ribbon type is preferably used. Moreover, it is preferable that the clearance between the can wall surface and the wing is in a range of 20 mm or less. Since this stirring blade does not have a central axis, not only the amount of polymer adhering to the stirring blade is small and the residual polymer in the can is reduced, but also there is no abnormal stagnation near the central axis, so the polymer is uniformly stirred and A homogeneous liquid crystal polymer with a small temperature distribution is obtained. Moreover, it is preferable to stir in the scraping direction where the liquid on the wall surface of the can is lowered by stirring in order to suppress the amount of polymer adhering to the stirring blade. Furthermore, in order to achieve uniform stirring, the amount of the content is preferably controlled to 50% to 90% of the capacity up to the upper stage of the stirring blade.
[0011]
The polyester vertical reactor used in the present invention is preferably an apparatus having two or more reaction cans capable of separately performing an acetylation reaction and a polycondensation reaction, and the ratio of the vertical length to the horizontal length of the reaction can is 1. Larger and less than 3 shapes are preferred.
[0012]
Liquid crystal polymer of the present invention is a polymer capable of forming a melt when anisotropic, before Symbol (I), a (II), (III), liquid crystal polyester consisting of structural units of (IV). The structural unit (I) is a structural unit of a polyester formed from p-hydroxybenzoic acid, and the structural unit (II) is 4,4′-dihydroxybiphenyl, 3,3 ′, 5,5′-tetramethyl-4. , 4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane and 4,4'-dihydroxy A structural unit generated from an aromatic dihydroxy compound selected from diphenyl ether, a structural unit (III) is a structural unit generated from ethylene glycol, and a structural unit (IV) is terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid. Acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenol) A) a structural unit formed from an aromatic dicarboxylic acid selected from ethane-4,4′-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid and diphenyl ether dicarboxylic acid; Each is shown. Of these, R ₁ is particularly

In which at least 70 mol% of the structural unit (II) is represented by R ₂ being

It is particularly preferable that those occupy 70 mol% or more of the structural unit (IV).
[0013]
The amount of copolymerization of the structural units (I), (II), (III) and (IV) is arbitrary. However, the following copolymerization amount is preferable from the viewpoint of fluidity.
[0014]
That is, from the viewpoint of heat resistance, flame retardancy and mechanical properties, the structural unit [(I) + (II)] is preferably 60 to 95 mol% of [(I) + (II) + (III)] 82-93 mol% is more preferable. In addition, the structural unit (III) is preferably 40 to 5 mol%, more preferably 18 to 7 mol% of [(I) + (II) + (III)]. The molar ratio of the structural units (I) / (II) is preferably 75/25 to 95/5, more preferably 78/22 to 93/7, from the viewpoint of the balance between heat resistance and fluidity. The structural unit (IV) is substantially equimolar to the structural unit [(II) + (III)].
[0015]
The above structural units in the polycondensation on Kipo Riesuteru is (I) in addition to components constituting ~ a (IV) 3,3'-diphenyl dicarboxylic acid, an aromatic such as 2,2'-diphenyl dicarboxylic acid Aliphatic dicarboxylic acids such as dicarboxylic acid, adipic acid, azelaic acid, sebacic acid and dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone, methylhydroquinone, 4,4′-dihydroxydiphenylsulfone, 4 , 4'-dihydroxydiphenyl sulfide, aromatic diols such as 4,4'-dihydroxybenzophenone, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4- Aliphatic, cycloaliphatic diols such as cyclohexanedimethanol and m- To further copolymerize aromatic hydroxycarboxylic acids such as droxybenzoic acid and 2,6-hydroxynaphthoic acid, p-aminophenol, p-aminobenzoic acid and the like in a small proportion within a range not impairing the object of the present invention. Can do.
[0016]
In the present invention, the method for producing a liquid crystal polymer by polymerization is not particularly limited. For example, the liquid crystal polyester can be produced by deacetic acid polymerization. Specifically, there is the method (1) or (2), but the method (2) is particularly preferable.
[0017]
(1) From diacylated products of aromatic dihydroxy compounds such as p-acetoxybenzoic acid and 4,4′-diacetoxybiphenyl and paradiacetoxybenzene, aromatic dicarboxylic acids such as terephthalic acid, ethylene glycol and aromatic dicarboxylic acids A method for producing a polyester, oligomer or bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid by a deacetic acid polycondensation reaction.
[0018]
(2) p-hydroxybenzoic acid, aromatic dihydroxy compounds such as 4,4′-dihydroxybiphenyl, hydroquinone, aromatic dicarboxylic acids such as acetic anhydride and terephthalic acid, and polyesters from ethylene glycol and aromatic dicarboxylic acids, A method in which a phenolic hydroxyl group is acylated by reacting with an oligomer or a bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid, followed by a deacetic acid polycondensation reaction.
[0019]
The polymerization proceeds even if this deacetic acid reaction is carried out in the absence of a catalyst, but it is preferable to add a metal compound such as stannous acetate, tetrabutyl titanate, potassium acetate, antimony trioxide, magnesium, sodium acetate as a catalyst. In some cases.
[0020]
Some of the liquid crystal polymers produced in the present invention can measure logarithmic viscosity in pentafluorophenol. In that case, the value measured at 60 ° C. at a concentration of 0.1 g / dl is 0.3 dl / g or more is preferable, and 0.5 to 3.0 dl / g is particularly preferable.
[0021]
Further, the melt viscosity of the liquid crystal polymer in the present invention is preferably 10 to 20,000 poise, and more preferably 20 to 10,000 poise.
[0022]
The melt viscosity is a value measured by an effect type flow tester under the condition of melting point (Tm) + 10 ° C. and shear rate of 1,000 (1 / second).
[0023]
Here, the melting point (Tm) is Tm1 + 20 after observing the endothermic peak temperature (Tm1) observed when the polymer having been polymerized is measured from room temperature under a temperature rising condition of 20 ° C./min in a differential scanning calorimeter. This is the endothermic peak temperature (Tm2) observed when the temperature is kept at a temperature of 5 ° C. for 5 minutes, then cooled to room temperature under a temperature drop condition of 20 ° C./minute, and then measured again under a temperature rise condition of 20 ° C./minute. .
[0024]
The liquid crystal polyester thus obtained exhibits good optical anisotropy, mechanical properties and heat resistance, can be used for ordinary injection molding, and can be injection molded into a three-dimensional molded product. Further, for the liquid crystalline polyester obtained in the present invention, glass fiber, carbon fiber, aromatic polyaramid fiber, potassium titanate fiber, gypsum fiber, ceramic fiber, boron whisker fiber, mica, silica, calcium carbonate, glass beads, glass Flakes, clays, wollastonite, titanium oxide, graphite and other fibrous, granular, powdery or plate-like inorganic fillers, antioxidants, thermal stabilizers, flame retardants, UV absorbers, lubricants, mold release Conventional additives such as agents, dyes and pigments and other thermoplastic resins can be added to impart desired properties.
[0025]
【Example】
Hereinafter, the present invention will be described in more detail by way of examples.
[0026]
Example 1
Polymerization was carried out as follows using two cans of transesterification reaction vessel A and polycondensation reaction vessel B having a vertical to horizontal ratio of 2.5 and an internal volume of 0.1 m ³ .
[0027]
FIG. 1 is a cross-sectional view of a polyester vertical reactor used in a reaction vessel B for polycondensation. In the reaction can 6, the stirring blade comprises a helical ribbon blade 4 and a bottom blade 5 supported by two frames 3 provided at a position where the distance from the can wall surface is 0.12 of the can diameter. The direction of rotation was the scraping direction.
[0028]
Reactor A was charged with 22.1 kg of p-hydroxybenzoic acid, 2.8 kg of 4,4′-dihydroxybiphenyl, 4.8 kg of polyethylene terephthalate, 2.5 kg of terephthalic acid, and 21.7 kg of acetic anhydride (mostly stirring blade). Equivalent to 65% of the volume up to the upper stage), the esterification reaction is carried out at 130 ° C. to 250 ° C. for 5 hours, and then transferred to the reaction vessel B to 250 ° C. to 315 ° C. over 2 hours. The pressure was reduced to 1 Torr and stirring was continued at 315 ° C. for 2 hours to complete the polycondensation reaction. Thereafter, the inside of the can was pressurized to 4 kg / cm ² , and then the polymer was discharged in a strand form through a base to form a pellet, thereby obtaining a pellet with a yield of 95%. This polymer had a logarithmic viscosity of 1.96 dl / g and a melt viscosity of 900 poise. At this time, the amount of residual polymer in the can was 1.0 kg (10 kg / m ³ per polymerization can internal volume). The theoretical structural formula of this polymer is shown below.
[0029]
[Chemical 9]

k / l / m / n = 80 / 7.5 / 12.5 / 20
When the inside of the can was observed from the looking glass of the reaction can B after the completion of the discharge, it was found that almost no polymer adhered to the stirring blade composed of the helical ribbon blade 4 and the bottom blade 5.
[0030]
Next, the pellets obtained were dried at 150 ° C. for one day and night, and then subjected to a Sumitomo Nestal injection molding machine Promat (manufactured by Sumitomo Heavy Industries, Ltd.). 1/8 ″ × 1/2 ″ × 5 ″). After purging for 10 minutes and purging for 2 shots, the purge polymer was normal without foaming. Strain rate was 10 mm and span distance was 50 mm. As a result of the bending test, the bending strength was 142 MPa and the bending elastic modulus was 10.8 GPa.
[0031]
Comparative Example 1
As a reaction vessel B for polycondensation, a helical ribbon blade having a central axis and attached to three fixing rods perpendicular thereto was used, and a polycondensation reaction was carried out in the same manner as in Example 1 to discharge and pelletize. . The yield was 90%, which was lower than Example 1. The amount of residual polymer in the can was 2.0 kg (20 kg / m ³ per polymerization can volume), which was larger than that in Example 1. When the inside of the can was observed from the looking lath in the same manner as in Example 1, it was found that a large amount of polymer adhered to the helical ribbon blade.
[0032]
Further, as in Example 1, the polymer was foamed when it was kept in the molding machine for 10 minutes and purged for 2 shots. Then, as a result of molding and testing in the same manner as in Example 1, the bending strength was 132 MPa and the bending elastic modulus was 9.3 GPa.
[0033]
【The invention's effect】
According to the present invention, a homogeneous liquid crystalline polyester having a good polymer yield and excellent thermal stability can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a polyester vertical reactor used in Example 1. FIG.
[Explanation of symbols]
1: Stirring shaft, 2: Steam outlet, 3: Frame, 4: Helical ribbon blade, 5: Bottom blade, 6: Reaction can

Claims (4)

When polymerizing a liquid crystal polymer comprising the structural units of (I), (II), (III) and (IV) below, a helical ribbon blade attached to a frame having no central axis and a bottom blade are included. A method for producing a liquid crystal polymer, wherein polymerization is performed using a vertical reactor equipped with a stirring blade.

(However, R ₁ in the formula is

One or more groups selected from R ₂

1 or more types of groups selected from Further, where X represents a hydrogen atom or a chlorine atom, the structural unit [(II) + (III) ] and the structural unit (IV) is substantially equimolar. ) 2. The method for producing a liquid crystal polymer according to claim 1, wherein the polymerization is carried out by a deacetic acid reaction. 2. The method for producing a liquid crystal polymer according to claim 1, wherein the frames to which the helical ribbon wings are attached are two or more frames located within 0.2 of the can diameter as a distance from the can wall surface. The method for producing a liquid crystal polymer according to claim 1, wherein the stirring direction of the stirring blade is a direction in which the reactant is scraped off.

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