JP4093535B2 - Method for producing low outgas liquid crystal polyester composition - Google Patents

Description

【００１７】
本発明において「低アウトガス」とは、成形品を加熱したときに発生する気体（アウトガス）が少ないことを意味する。
【００１８】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。
本発明に係る液晶ポリエステルは、ｐ−ヒドロキシ安息香酸、テレフタル酸、４，４’−ジヒドロキシビフェニル（これらの誘導体を含む。以下、同じ。）を８０モル％以上含むモノマー群を、これらモノマー群中の水酸基の少なくとも一部をアシル化および／またはモノマー群中のカルボキシル基の少なくとも一部をフェニルエステル化した後に、重縮合してなる融点３２０℃以上のものである。融点が３２０℃以上とは、ＤＳＣまたはＴＭＡ分析において、３２０℃以上の領域にピークが検出されることをいい、３２０℃以下に別個のピークが検出されてもよい。この融点に係る要求は、例えば、重縮合に係るモノマー中にｐ−ヒドロキシ安息香酸を５０モル％以上含ませること、あるいは、ｐ−ヒドロキシ安息香酸、テレフタル酸、４，４’−ジヒドロキシビフェニル以外の重縮合に係るモノマーを２０モル％以下、好ましくは１０モル％以下とすること等により達成できる。
【００１９】
上記のモノマー組成条件を満たすことにより、液晶ポリエステルの主鎖部は芳香族環が主成分となり、基本的耐熱性に加えて良好な成形性が確保され（すなわち溶融状態における剪断発熱が抑制される。）、低アウトガス性能を発揮するための基礎特性が確保される。この耐熱性と成形性が確保される限り、残りの２０モル％以下を構成するモノマーは限定されないが、イソフタル酸、２，６−ヒドロキシナフテン酸、ヒドロキノン等の芳香族環を有するモノマーを使用し、全芳香族液晶ポリエステル構造とすることが好ましいが特に限定されるものではない。好ましくは、ｐ−ヒドロキシ安息香酸４０〜８０モル％、テレフタル酸１０〜４０モル％、４，４’−ジヒドロキシビフェニル１０〜４０モル％（３者を合計して１００モル％とする。）とし、必要に応じて、上記した他の芳香族系モノマーで所定モル％を置換する。
【００２０】
重縮合前に、モノマー中の水酸基の少なくとも一部をアシル化および／またはモノマー群中のカルボキシル基の少なくとも一部をフェニルエステル化する。アシル化の例としては、無水酢酸または酢酸でアセチル化することが好ましい。アシル化反応、アセチル化反応は、公知の方法で行うことができる。工程上は適宜の方法で行うことができる。アシル化（アセチル化）したモノマーを別個に用意して重縮合反応に供する方法で行うことができる。例えばｐ−ヒドロキシ安息香酸をｐ―アセトキシ安息香酸として使用する。また、モノマー、無水酢酸、必要に応じて触媒、を反応槽に投入した後、重縮合反応に先立ち、または重縮合反応と併行して行うことができる。後者の方法が工業的には有利である。モノマー群中のカルボキシル基の少なくとも一部をフェニルエステル化するには、フェノールまたはフェノール誘導体によって公知の方法で行うことができる。
【００２１】
無機充填材は特に制限はなく、公知のものが使用でき、これらを配合することによる充填効果で荷重たわみ温度２３０℃以上が得られる。好ましい無機充填材を例示すれば、二硫化モリブデン、タルク、マイカ、ガラスフレーク、クレー、セリサイト、炭酸カルシウム、珪酸カルシウム、シリカ、アルミナ、水酸化アルミニウム、水酸化カルシウム、黒鉛、非晶質炭素、チタン酸カリウム、ガラス繊維、炭素繊維、各種ウィスカー等が挙げられる。これらは、単独で使用しても２種類以上使用してもよい。これら無機充填材の中でも、タルク、マイカ、ミルドガラス、ガラス繊維が成形性、耐熱性、低アウトガス性のバランスに優れるので好ましい。
【００２２】
本発明では、液晶ポリエステル９０〜４０wt％と無機充填材１０〜６０wt％（両者を合計して１００wt％とする。）を溶融混練する。無機充填材が１０wt％以下では異方性が高くなり成形品の表面外観が悪くなり、６０wt％を超えると成形性および低アウトガス性が低下する。なお、混練に際して、液晶ポリエステルと無機充填材のほかに、後記するような他の成分を適宜加えて溶融混練することができる。
【００２３】
本発明では、溶融混練手段として、一対の２条スクリュウおよび開放口（ベント口）を有する混練機を使用する。例えば、ベント口を有する２軸混練押出機である。一対のスクリュウの回転方向は、被混練材料の切り替えし（表面の更新）が十分に行われることから、同方向が好ましい。開放口は被混練材料から耐ブリスター性悪化の原因のひとつである揮発分を除去するためのもので、大気開放でも真空ポンプに連結して減圧してもよい。また、開放口は複数個設けてもよい。
【００２４】
一対のスクリュウは、少なくとも１つのニーディングディスク部を有している。ニーディングディスク部は単数または複数枚のニーディングディスクから成る。スクリュウおよびニーディングディスクは、スクリュウ軸に直角な断面形状が楕円状または長円形状であり、一対が互いに噛合されている。このような構造では、ニーディングディスクのチップ部とバレル内面との隙間が、たとえば０．５ｍｍ以下と、極端に狭いために大きな剪断力が発生し溶融混練が効果的に行われる反面、該チップ部において局部発熱が生じる。本発明者らは、均一な溶融混練を得ることと過度の剪断応力履歴を避けることとのバランスを最適化することが耐ブリスター性向上に大きな影響を与えていると考えた。さらに、ニーディングディスク部は混練に重要な働きをするが、これを過度に設けると、被混練材全体に大きな剪断熱が発生しポリマーの劣化の原因となる。これを避けるために材料の温度を一定値以下に保つには、スクリュ回転速度を上げることができず、生産性が制限されるという問題が発生していると考えた。本発明は、このような混練状態の詳細な解析に基づくものである。
【００２５】
本発明では、スクリュウおよびニーディングディスクの断面形状の長軸長さを短軸長さで除した値（以下、「噛合率」という。）を、１．６０以上、好ましくは１．６２以上とする。汎用の一対のスクリュを有する混練機の噛合い率は１．５５以下である。また、当該噛合率は、搬送を主機能とする螺旋状スクリュウの断面からも求めることができるが、ニーディングディスクの断面から求めるほうがより簡便である。なお、市場から入手可能な噛合率１．６２の当該発明に係る混練機として、神戸製鋼（株）のＨＹＰＥＲＫＴＸシリーズがある。
【００２６】
当該スクリュウ噛合率により、被混練材料は、すべり等が抑制された状態で、剪断応力をより均一に受け、剪断発熱がより均一に生じる。液晶ポリエステルの中でも、本発明に係る液晶ポリエステルのように融点が３２０℃を超えかつ芳香族モノマーを主繰り返し単位とするポリマーは、バレルヒーターからの予熱のみで溶融することは困難であり、またいったん溶融すると当該液晶ポリエステルの見かけ粘度は急激に低下するから、剪断応力を均一に受けさせ、剪断発熱を被混練材料内に均一に発生させてポリマー表面のみが溶融することを避け、全体を融解することが、局部的な劣化を抑え、これがアウトガスの発生を抑制するものと考えられる。本発明では、「噛合率」を１．６０以上、好ましくは１．６２以上としたことにより、液晶ポリエステルを溶融させる熱エネルギーの剪断発熱に依存する割合が高まり、かつ均一な剪断発熱の発生が確保される。また、当該噛合率により、より大きな空隙部がスクリュとバレル間に発生するので、被混練材料が剪断発熱を受けた直後に十分な空隙中に開放されて空冷されると同時にアウトガスの発生原因となる可能性の高い揮発成分を排出することが可能となると考えられる。揮発成分は開放口から混練機の外部へ排出される。
【００２７】
本発明の効果をさらに発揮させるには、単数又は複数のニーディングディスクから成るニーディングディスク部を一対のスクリュウの、開放口の上流側および下流側のそれぞれに少なくとも一つ設けることにより、被混練材料中の揮発分の排出を確保できる。
【００２８】
ニーディングディスク部の構成の例としては、（１）複数枚が右方向捩じりθ°で構成されるニーディングディスク、（２）左方向捩じりθ°で構成されるニーディングディスク、（３）単一ニーディングディスク等から成るものが含まれ、θの値としては、例えば、１５°、３０°、４５°がある。
【００２９】
該ニーディングディスク部のそれぞれの長さをバレル内径に対して３倍以下とし、かつ該ニーディングディスク部の長さの総和をバレル内径に対して８倍以下とすることが好ましい。一箇所におけるニーディングディスク部の長さをバレル内径に対して３倍以下とすることにより、被混練材料に過度の連続した剪断発熱が生じることを回避できる。３倍以上ではアウトガス発生量が増加するので好ましくない。また、スクリュウ中に一箇所以上設けられた各ニーディングディスク部の長さの総和をバレル内径に対して８倍以下とすることにより、被混練材料に過度の剪断発熱履歴が生じることを避けることができる。８倍以上とするとアウトガス発生量が増加するので好ましくない。
【００３０】
上記諸条件を確保すると、確実かつ均一な混練および被混練材全体における剪断熱の局部的発生および過度の蓄積を回避することが達成され、また、スクリュ回転速度の自由度が確保されて材料の十分な吐出量が得られる。
【００３１】
本発明においては、当該混練機のホッパーに投入される液晶ポリエステルの含有水分を５００ｐｐｍ以下として、剪断発熱発生時において水が介在する影響を抑制することが好ましい。水分が５００ｐｐｍより多いと、当該溶融工程で液晶ポリエステルの分解が生じて耐ブリスター性が劣化することがある。当該含有水分レベルは、例えば、１５０℃に設定した乾熱オーブン中に液晶ポリエステルを１時間以上静置して、あるいは、１５０℃に設定したホッパードライヤーで液晶ポリエステルを１時間以上乾燥処理して得ることができる。ただし、５００ｐｐｍ以下を維持することができていれば必ずしも乾燥工程を必要としない。
【００３２】
本発明においては、当該混練機のホッパーに投入される液晶ポリエステルの５０wt％以上を粉末体としてペレット含有量を低下させ、剪断発熱発生時においてペレット表面のみが溶融して生じるすべり現象やペレットに対して剪断破壊が生じることを抑制することが好ましい。これらは、被混練材料の均一な溶融混練を阻害することあり、耐ブリスター性が劣化することがある。粉末状液晶ポリエステルの粒径レベルは、上記現象の発生を抑制できる程度で十分であり、ペレットが粉砕されたものであれば十分であるが、２０メッシュ通過レベルであることが好ましい。
【００３３】
充填材は、混練機の一又は複数の個所からサイドフィードするのが好ましい。ガラス繊維や炭素繊維のような繊維状の充填材は、繊維の切断を避けるために、ポリマーが十分可塑化した状態で添加するのが好ましい。
【００３４】
本発明の液晶ポリエステル組成物には、実用上の物性を改良するために無機充填剤の他に有機充填剤、各種の従来公知の安定剤、酸化防止剤、紫外線吸収剤、顔料、染料、改質剤等、を加えてもよい。特に、下記式(1)で示される熱安定性に優れた亜リン酸エステルを、特に好ましくは当該樹脂組成物の荷重たわみ温度を考慮して２３０℃以上の融点を有する１種または２種以上０.０１〜１重量部を添加することは、液晶ポリエステルを溶融させる熱エネルギーの剪断発熱における酸化劣化対策として有効である。
【化３】

【００３５】
具体的な化合物としては、サイクリックネオペンタトライルビス（２，４−ジ−ｔｅｒｔ−ブチルフェニル）ホスファイト（市場からはアデカスタブＰＥＰ−２４Ｇ、融点１７０℃：旭電化（株）製が入手できる。）およびサイクリックネオペンタトライルビス（２，６−ジ−ｔｅｒｔ−ブチルフェニル）ホスファイト（市場からはアデカスタブＰＥＰ−３６、融点２３７℃：旭電化（株）製が入手できる。）が好ましい。
【００３６】
【発明の効果】
本発明の方法によれば、液晶ポリエステルと無機充填材とを混練するに際して、スクリュウ噛合率１．６以上の２軸混練機を用いることによって、アウトガスの発生が低減された低アウトガス液晶ポリエステル組成物が得られる。
【００３７】
【実施例】
以下、実施例および比較例によって具体的に説明する。
＜液晶ポリエステルの合成＞
液晶ポリエステルの合成を以下のように行った。
液晶ポリエステルAの合成：
ＳＵＳ３１６を材質とし、ダブルヘリカル攪拌翼を有する６L重合槽（日東高圧社製）にｐ−ヒドロキシ安息香酸１１０５．０ｇ（８．００ｍｏｌ）、テレフタル酸７４４．８ｇ（４．００ｍｏｌ）、４，４’−ジヒドロキシビフェニル６６４．５ｇ(４．００ｍｏｌ)を仕込み、重合槽の減圧−窒素注入を２回行なって窒素置換を行なった後、無水酢酸１７３１．４ｇ（１６．９６ｍｏｌ）を添加し、攪拌翼の回転数１００ｒｐｍで１５０℃まで１時間で昇温して還流状態で２時間アセチル化反応を行なった。アセチル化終了後、酢酸留出状態にして０．５℃／分で昇温して、３３０℃において重合物を重合槽下部の抜き出し口から取り出した。取り出した重合体を粉砕機により２０メッシュ以下に粉砕した。次に、円筒型回転式リアクターを有する加熱装置（旭硝工(株)製）により固相重合を行なった。円筒型回転式リアクターに粉砕した重合体を投入し、窒素を１リットル／分流通させ、回転数２０ｒｐｍで２８０℃まで２時間かけて昇温して２８０℃で３時間保持した後、３００℃まで３０分で昇温して３時間保持し、３２０℃まで３０分で昇温して３時間保持し、さらに、３４０℃まで３０分で昇温して２時間保持した後、室温まで１時間で冷却して重合体を得た。得られた重合体の融点をＤＳＣで測定したところ、融点は４１０℃であった。また、４４０℃における見掛け粘度は２５００ポイズであった。
【００３８】
液晶ポリエステルBの合成：
ＳＵＳ３１６を材質とし、ダブルヘリカル攪拌翼を有する６L重合槽（日東高圧社製）にｐ−ヒドロキシ安息香酸１３３０．１ｇ（９．６３ｍｏｌ）、イソフタル酸１３３．４ｇ（０．８０３ｍｏｌ）、テレフタル酸４００．０ｇ（２．４０８ｍｏｌ）および４，４’−ジヒドロキシビフェニル５９７．７ｇ(３．２１ｍｏｌ)を仕込み、重合槽の減圧−窒素注入を２回行なって窒素置換を行なった後、無水酢酸１７３６．９ｇ（１７．０１ｍｏｌ）を添加し、攪拌翼の回転数１００ｒｐｍで１５０℃まで１時間で昇温して還流状態で２時間アセチル化反応を行なった。アセチル化終了後、酢酸留出状態にして０．５℃／分で昇温し、３２０℃において重合物を重合槽下部の抜き出し口から取り出した。取り出した重合体を粉砕機により２０メッシュ以下に粉砕した。次いで、円筒型回転式リアクターを有する加熱装置（旭硝工(株)製）により固相重合を行なった。円筒型回転式リアクターに粉砕した重合体を投入し、窒素を１リットル／分流通させ、回転数２０ｒｐｍで２９０℃まで２時間かけて昇温して２９０℃で６時間保持した後、室温まで１時間で冷却して重合体を得た。得られた重合体の融点をＤＳＣで測定したところ、融点は３５８℃であった。また、３７０℃における見掛け粘度は９１０ポイズであった。
【００３９】
以下の組成の被混練材料I〜IIIを使用した。
被混練材料Ｉ：
（１）液晶ポリエステル：液晶ポリエステルＡ ６０ｗｔ％
（２）無機充填剤：粉砕グラスファイバー（商品名“MF-20JMH1-20、旭ファイバーグラス社製） ４０ｗｔ％
被混練材料II：
（１）液晶ポリエステル：液晶ポリエステルB ６０ｗｔ％
（２）無機充填剤：粉砕グラスファイバー（商品名“MF-20JMH１-20、旭ファイバーグラス社製）２０ｗｔ％およびグラスファイバー（商品名“PX-1”、旭ファイバーグラス社製）２０ｗｔ％
被混練材料III：
（１）液晶ポリエステル：液晶ポリエステルB ６０ｗｔ％
（２）無機充填剤：粉砕グラスファイバー（商品名“MF-20JMH1-20”、旭ファイバーグラス社製）２０ｗｔ％およびグラスファイバー（商品名“PX-1”、旭ファイバーグラス社製）２０ｗｔ％
（３）酸化防止剤：サイクリックネオペンタトライルビス（２，６−ジ−ｔｅｒｔ−ブチルフェニル）ホスファイト（アデカスタブＰＥＰ−３６：旭電化（株）製） ０．１重量部
【００４０】
以上の被混練材料I〜IIIにおいて、液晶ポリエステルのペレットと粉末の割合および水分含有量を変えたものを使用した。水分測定は、ＪＩＳ−Ｋ５１０１に準拠して加熱減量法によって行った。呼び寸法５０×３０ｍｍの平形はかり瓶の蓋を外して１０５℃に保った乾燥機で２時間乾燥し、乾燥終了後、はかり瓶をデシケーター中で常温まで放冷して、はかり瓶に蓋をして質量を１ｍｇの桁まで測った。試料２０ｇをこのはかり瓶に１ｍｇの桁まで量り取り、蓋をして再び質量を測定した。はかり瓶の蓋を取り、試料の入ったはかり瓶を１０５℃に保った乾燥機で２時間乾燥し、乾燥終了後、はかり瓶をデシケーター中で常温まで放冷して、はかり瓶に蓋をして質量を１ｍｇの桁まで測った。そして加熱前後の質量から加熱減量を算出した。
【００４１】
使用した混練機２種類および被混練材料の処理条件は以下のとおりであった。＜溶融混練機Ａ＞実施例１〜１２で使用した。
スクリュウ噛合率：１．６２
バレル寸法：内径４６ｍｍ、Ｌ／Ｄ＝３６
スクリュ回転数：３００ｒｐｍ
被混練材料Ｉに対する温度条件：
バレル温度：Ｃ１：３８０℃、Ｃ２：４１０℃、Ｃ３：４１０℃、Ｃ４：４１０℃、Ｃ５：４１０℃、Ｃ６：４１０℃、Ｃ７：３９０℃、Ｃ８：３７０℃、Ｃ９：３７０℃
ヘッド温度：４１０℃
ダイス温度：４１０℃。
被混練材料IIおよびIIIに対する温度条件：
バレル温度：Ｃ１：３００℃、Ｃ２：３２０℃、Ｃ３：３５０℃、Ｃ４：３７０℃、Ｃ５：３７０℃、Ｃ６：３７０℃、Ｃ７：３５０℃、Ｃ８：３３０℃、Ｃ９：３３０℃
ヘッド温度：３５０℃、
ダイス温度：３５０℃。
【００４２】
＜溶融混練機Ｂ＞比較例１〜６で使用した。
スクリュウ噛合率：１．５５
バレル寸法：内径４６ｍｍ、Ｌ／Ｄ＝３６
スクリュ回転数：３００ｒｐｍ
被混練材料Iに対する温度条件：
バレル温度：Ｃ１：３８０℃、Ｃ２：４１０℃、Ｃ３：４１０℃、Ｃ４：４１０℃、Ｃ５：４１０℃、Ｃ６：４１０℃、Ｃ７：３９０℃、Ｃ８：３７０℃、Ｃ９：３７０℃
ヘッド温度：４１０℃、
ダイス温度：４１０℃。
被混練材料IIおよびIIIに対する温度条件：
バレル温度：Ｃ１：３００℃、Ｃ２：３２０℃、Ｃ３：３５０℃、Ｃ４：３７０℃、Ｃ５：３７０℃、Ｃ６：３７０℃、Ｃ７：３５０℃、Ｃ８：３３０℃、Ｃ９：３３０℃
ヘッド温度：３５０℃、
ダイス温度：３５０℃。
【００４３】
なお、混練機Ａと混練機Ｂのスクリュウ構造は、いずれも一対の同方向回転スクリュウであり、ニーディングディスク部の長さがバレル内径の３倍以下でその長さの総計がバレル内径の８倍以下であり、噛合率を除いて実質的に同一であった。
【００４４】
＜液晶ポリエステル組成物の製造＞
被混練材料Ｉ〜IIIを溶融混練機ＡとＢでそれぞれ溶融混練し、ダイスから押し出して得られたストランドをペレタイザーで切断して液晶ポリエステル組成物のペレットを得た。
【００４５】
＜荷重たわみ温度測定用試験片の製造＞
以上のようにして得られた液晶ポリエステル組成物ペレットを射出成形機のホッパーに投入して、以下の条件で射出成形した。なお、荷重たわみ温度の試験片形状はＡＳＴＭ６４８に準拠したものを使用した。
射出成形機：住友重機械工業製：ＳＧ‐２５、型締め圧：２５トン
被混練材料Ｉの成形条件：
バレル温度：Ｃ１：３７０℃、Ｃ２：４００℃、Ｃ３：４１０℃
ノズル温度：４１０℃、
金型温度：１５０℃
射出速度：１００ｍｍ／ｓｅｃ
被混練材料IIおよびIIIの成形条件：
バレル温度：Ｃ１：３１０℃、Ｃ２：３４０℃、Ｃ３：３５０℃
ノズル温度：３５０℃、
金型温度：８０℃
射出速度：１００ｍｍ／ｓｅｃ
【００４６】
（荷重たわみ温度とアウトガスの測定）
荷重たわみ温度：ＡＳＴＭ６４８に準拠した。２５０℃で変位が規定値以下であったので、いずれも２５０℃以上であったことを確認して、その時点で測定を終了した。
アウトガス：射出成形したＡＳＴＭ６４８試験片を、１ｍｍφメッシュの粉砕機により粉砕し、得られた粉砕物を２０ｍｌのバイアル瓶に入れて密封した後、１５０℃で２４時間熱処理を行った。発生した酢酸およびフェノールのガスをヒューレットパッカード社製のヘッドスペースサンプラー（ＨＰ７６９４）を接続したガスクロマトグラフィー（ＨＰ６８９０）により定量した。カラムには化学品検査協会製のＧ−１００（４０ｍ）を用い、その他の条件は、初期温度４５℃、昇温速度２０℃／分、最終温度２８０℃、ヘリウム圧８.３psiおよびスプリット比２.０として、ＦＩＤ検出器を用いて測定を行った。
【００４７】
結果を表１〜３に示す。
【００４８】
【表１】

【００４９】
【表２】

【００５０】
【表３】

【００５１】
表１，２，３に示すように、本発明に従って製造された液晶ポリエステル樹脂組成物(実施例)は、比較例に比べてアウトガスの発生量が少なかった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal polyester composition containing an inorganic filler that provides a molded article with less corrosive outgas generated under a high temperature environment.
[0002]
[Prior art]
Liquid crystalline polyester has excellent moldability and is used as a constituent material for small electronic components. Among them, when a liquid crystalline polyester is produced by polycondensation containing p-hydroxybenzoic acid, terephthalic acid, and 4,4′-dihydroxybiphenyl as main components, a thermotropic liquid crystalline copolyester having a melting point of 320 ° C. or more is obtained. If the filler is appropriately melt-kneaded, a composition having a deflection temperature under load of 230 ° C. or more can be obtained.
[0003]
The liquid crystal polyester composition is used in various electrical and electronic parts by taking advantage of its thin moldability based on its excellent moldability and fluidity, high dimensional accuracy, and the highest level of heat resistance among thermoplastic resin compositions. In particular, it is preferably used for constituent materials such as SMT-compliant electric / electronic components that require heat resistance and other structural member materials that are exposed to a high temperature environment such as a solder melting process.
[0004]
However, a thermotropic liquid crystal copolyester produced by a conventionally known method is corrosive to metal conductive parts (for example, electronic circuits) of electric / electronic parts in a high temperature environment (for example, soldering process, surface mounting, etc.). It has been found to generate outgas and its corrosiveness is recognized as a problem. Further, the components and composition ratios of the corrosive outgas vary somewhat depending on the method for producing the liquid crystal polyester, but generally acetic acid and phenol are the main components.
[0005]
The thermotropic liquid crystal copolyester can be obtained by polycondensation of the above monomer groups as they are. In order to improve productivity, some or all of the hydroxyl groups in these monomers are acylated and / or carboxyl groups in the monomer groups. At least a part of these is phenylesterified and polycondensed. In particular, polycondensation of acetic anhydride and / or acetylated with acetic acid is performed. Therefore, since acetic acid used for acylation is inevitably generated in the polycondensation reaction process by transesterification, etc., it can be obtained from the liquid crystal polyester produced in this way unless the acetic acid is completely removed. Depending on the usage environment, acetic acid and the like are inevitably released from the molded product as outgas. In order to reduce the amount of acetic acid generated, it is effective to distill off the system while controlling the relative amount of acetic anhydride or the like present in the polycondensation system. However, removal in the polycondensation step alone is not sufficient to support applications that are used under high temperature conditions. Furthermore, an effective removal means is required. In some cases, at least a part of the carboxyl group in the monomer is subjected to phenyl esterification with phenol or a phenol derivative and polycondensed, but in that case, there is a problem in that phenols are similarly generated as outgas.
[0006]
Further, since the polycondensation temperature is high and the reaction time is long, a partial decomposition reaction of the monomer group cannot be avoided, and phenol is generated as a decomposition product. Although decomposition is suppressed by carrying out acylation (acetylation) or the like to increase the reaction efficiency and shorten the reaction time, the generation of phenol has not been completely eliminated.
[0007]
Electrical and electronic parts including metal conductive parts, such as relays, switches, connectors, sockets, resistors, capacitors, motors, oscillators, printed wiring boards, and power modules, corrosive outgassing due to thermal history during surface mounting If the metal conductive part is oxidized by the above, a corrosion film is formed, resulting in poor conduction, or mechanical electrical contacts, a carbide layer is formed mainly on the contact part due to discharge during contact operation. It has been pointed out that there are problems such as contact failure due to the generation. The formation of a carbide layer in these parts is presumed to be due to corrosive outgas being carbonized and deposited by arc discharge and causing abnormal conduction. In particular, this corrosion is a serious problem in parts such as relays and switches that require good contact characteristics to be maintained over a long period of time.
[0008]
In addition, in recent years, thermotropic liquid crystal copolyesters are also used for various components used in HDDs (carriage, chassis, actuator VCM coil holding parts, head storage member when stopped, etc.) and similar components in FDD, optical disk drives, etc. As for the magnetic or optical data reading part essential for these devices, there is a concern about the deterioration of the function due to the corrosive outgas generated from the resin as described above.
[0009]
The field of electrical and electronic parts in which thermotropic liquid crystal copolyester is used is becoming increasingly smaller and lower in voltage, and the formation of corrosion films and the formation of carbide layers as described above are more poor than before. Therefore, the thermotropic liquid crystal copolyester is required to generate less corrosive outgas.
[0010]
As a method for reducing the corrosive outgas of the thermotropic liquid crystal copolyester, a method of blending a gas absorbing material (Japanese Patent Laid-Open No. 8-333505), a method of sealing molecular chain ends with a monofunctional monomer (Japanese Patent Laid-Open No. Hei 3) -203925, JP-A-4-249528, and JP-A-8-53543) have already been proposed, but these are not necessarily satisfactory methods.
[0011]
[Problems to be solved by the invention]
In view of such circumstances, the present invention provides a liquid crystal polyester composition that is excellent in low outgassing properties while maintaining basic heat resistance such as moldability and melting point / load deflection temperature of the liquid crystal polyester composition. The object is to improve the reliability of structural members exposed to high thermal environments such as electrical and electronic parts as constituent materials.
[0012]
[Means for Solving the Problems]
The present invention has been made as a result of various studies on the relationship between “outgas” and “melt-kneading of a composition of a liquid crystal polyester and an inorganic filler”.
In the first aspect of the present invention, a monomer group containing 80 mol% or more of p-hydroxybenzoic acid, terephthalic acid, and 4,4′-dihydroxybiphenyl (including derivatives thereof) is added to at least one hydroxyl group in these monomer groups. 90 to 40 wt% of a liquid crystal polyester having a melting point of 320 ° C. or higher and 10 to 60 wt% of an inorganic filler obtained by acylating a part and phenylesterifying at least a part of a carboxyl group in a monomer group, In a method for producing a liquid crystal polyester composition having a deflection temperature under load of 250 ° C. or higher obtained by melt kneading in a kneader having an open port for removing volatile components from a material to be kneaded and a pair of screws, the screw of the kneader The present invention relates to a method for producing a low outgas liquid crystal polyester composition, wherein the meshing rate is 1.60 or more.
[0013]
A second aspect of the present invention relates to a method for producing a low outgassing liquid crystal polyester composition according to the first aspect of the present invention, wherein the acylation is acetylation using acetic acid or acetic anhydride.
[0014]
A third aspect of the present invention relates to a method for producing a low outgas liquid crystal polyester composition according to the first or second aspect of the present invention, wherein the water content of the liquid crystal polyester charged into the hopper of the kneader is 500 ppm or less. It is.
[0015]
A fourth aspect of the present invention is the method for producing a low outgas liquid crystal polyester composition according to any one of the first to third aspects of the present invention, wherein 50% or more of the liquid crystal polyester charged into the hopper of the kneader is a powder. It is about.
[0016]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, 0.01 to 1 part by weight of one or more phosphites represented by the formula (1) is added. The present invention relates to a method for producing a low outgas liquid crystal polyester composition.
[Chemical 2]

[0017]
In the present invention, “low outgas” means that there is little gas (outgas) generated when the molded product is heated.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
The liquid crystal polyester according to the present invention includes a monomer group containing 80 mol% or more of p-hydroxybenzoic acid, terephthalic acid, 4,4′-dihydroxybiphenyl (including these derivatives, the same shall apply hereinafter). These are those having a melting point of 320 ° C. or higher formed by acylating at least part of the hydroxyl groups and / or polyesterifying at least part of the carboxyl groups in the monomer group. The melting point of 320 ° C. or higher means that a peak is detected in a region of 320 ° C. or higher in DSC or TMA analysis, and a separate peak may be detected at 320 ° C. or lower. The requirement concerning this melting point is, for example, that p-hydroxybenzoic acid is contained in a monomer related to polycondensation in an amount of 50 mol% or more, or other than p-hydroxybenzoic acid, terephthalic acid, and 4,4′-dihydroxybiphenyl. This can be achieved by adjusting the monomer related to polycondensation to 20 mol% or less, preferably 10 mol% or less.
[0019]
By satisfying the above monomer composition conditions, the main chain portion of the liquid crystal polyester has an aromatic ring as a main component, and in addition to basic heat resistance, good moldability is ensured (that is, shear heat generation in the molten state is suppressed). ), The basic characteristics to achieve low outgas performance are ensured. As long as this heat resistance and moldability are ensured, the monomers constituting the remaining 20 mol% or less are not limited, but monomers having an aromatic ring such as isophthalic acid, 2,6-hydroxynaphthenoic acid, hydroquinone, etc. are used. Although it is preferable to have a wholly aromatic liquid crystal polyester structure, it is not particularly limited. Preferably, p-hydroxybenzoic acid is 40 to 80 mol%, terephthalic acid is 10 to 40 mol%, 4,4'-dihydroxybiphenyl is 10 to 40 mol% (the total of the three is 100 mol%). If necessary, a predetermined mol% is substituted with the other aromatic monomer described above.
[0020]
Prior to polycondensation, at least a part of the hydroxyl groups in the monomer is acylated and / or at least a part of the carboxyl groups in the monomer group is phenylesterified. As an example of acylation, acetylation with acetic anhydride or acetic acid is preferred. The acylation reaction and acetylation reaction can be carried out by known methods. The process can be performed by an appropriate method. The method can be carried out by separately preparing acylated (acetylated) monomers and subjecting them to a polycondensation reaction. For example, p-hydroxybenzoic acid is used as p-acetoxybenzoic acid. In addition, the monomer, acetic anhydride and, if necessary, a catalyst can be added to the reaction tank, and can be performed prior to the polycondensation reaction or concurrently with the polycondensation reaction. The latter method is industrially advantageous. The phenyl esterification of at least a part of the carboxyl groups in the monomer group can be carried out by a known method using phenol or a phenol derivative.
[0021]
There is no restriction | limiting in particular in an inorganic filler, A well-known thing can be used, The deflection temperature of load 230 degreeC or more is obtained by the filling effect by mix | blending these. Examples of preferred inorganic fillers include molybdenum disulfide, talc, mica, glass flake, clay, sericite, calcium carbonate, calcium silicate, silica, alumina, aluminum hydroxide, calcium hydroxide, graphite, amorphous carbon, Examples include potassium titanate, glass fiber, carbon fiber, and various whiskers. These may be used alone or in combination of two or more. Among these inorganic fillers, talc, mica, milled glass, and glass fiber are preferable because of excellent balance of formability, heat resistance, and low outgassing properties.
[0022]
In the present invention, 90 to 40 wt% of the liquid crystalline polyester and 10 to 60 wt% of the inorganic filler (both are 100 wt% in total) are melt-kneaded. If the inorganic filler is 10 wt% or less, the anisotropy becomes high and the surface appearance of the molded product is deteriorated, and if it exceeds 60 wt%, the moldability and low outgassing properties are lowered. In addition, in kneading, in addition to the liquid crystalline polyester and the inorganic filler, other components as described later can be appropriately added and melt-kneaded.
[0023]
In the present invention, a kneader having a pair of two-screws and an open port (vent port) is used as the melt kneading means. For example, a twin-screw kneading extruder having a vent port. The direction of rotation of the pair of screws is preferable because the material to be kneaded is sufficiently switched (updating the surface). The open port is for removing volatile components which are one of the causes of deterioration of blister resistance from the material to be kneaded, and may be decompressed by being connected to a vacuum pump even in the open atmosphere. Further, a plurality of open ports may be provided.
[0024]
The pair of screws has at least one kneading disk portion. The kneading disk portion is composed of one or a plurality of kneading disks. The cross section of the screw and the kneading disk perpendicular to the screw axis is an ellipse or an ellipse, and a pair is engaged with each other. In such a structure, the gap between the tip portion of the kneading disk and the inner surface of the barrel is extremely narrow, for example, 0.5 mm or less, so that a large shearing force is generated and melting and kneading is effectively performed. Local heat generation occurs in the part. The present inventors thought that optimizing the balance between obtaining uniform melt kneading and avoiding excessive shear stress history has a great influence on the improvement of blister resistance. Furthermore, the kneading disk part plays an important role in kneading, but if it is excessively provided, a large shearing heat is generated in the entire material to be kneaded, causing deterioration of the polymer. In order to avoid this, in order to keep the temperature of the material below a certain value, it was considered that there was a problem that the screw rotation speed could not be increased and productivity was limited. The present invention is based on a detailed analysis of such a kneaded state.
[0025]
In the present invention, a value obtained by dividing the major axis length of the cross-sectional shapes of the screw and kneading disk by the minor axis length (hereinafter referred to as “meshing ratio”) is 1.60 or more, preferably 1.62 or more. To do. The meshing rate of a kneader having a pair of general-purpose screws is 1.55 or less. Further, the meshing rate can be obtained from a cross section of a spiral screw whose main function is conveyance, but it is easier to obtain it from a cross section of a kneading disk. As a kneader according to the present invention having a meshing rate of 1.62 available from the market, there is a HYPERKTX series of Kobe Steel.
[0026]
Due to the screw meshing rate, the material to be kneaded is subjected to shear stress more uniformly in a state where slippage or the like is suppressed, and shear heat generation occurs more uniformly. Among liquid crystal polyesters, a polymer having a melting point exceeding 320 ° C. and having an aromatic monomer as a main repeating unit as in the liquid crystal polyester according to the present invention is difficult to melt only by preheating from a barrel heater. When melted, the apparent viscosity of the liquid crystalline polyester rapidly decreases, so that the shear stress is uniformly applied, and shear heat is generated uniformly in the material to be kneaded to avoid melting only the polymer surface and melt the whole. This is considered to suppress local deterioration, which suppresses the generation of outgas. In the present invention, by setting the “meshing ratio” to 1.60 or more, preferably 1.62 or more, the ratio depending on the shear heating of the heat energy for melting the liquid crystal polyester is increased, and the generation of uniform shear heating is generated. Secured. In addition, since a larger gap portion is generated between the screw and the barrel due to the meshing rate, the material to be kneaded is released into a sufficient gap immediately after receiving shearing heat generation and air-cooled, and at the same time, causes of outgas generation. It is thought that it is possible to discharge volatile components that are likely to become. Volatile components are discharged from the opening to the outside of the kneader.
[0027]
In order to further demonstrate the effects of the present invention, by providing at least one kneading disk portion composed of one or a plurality of kneading disks on each of the upstream side and the downstream side of the pair of screws, Emission of volatile matter in the material can be secured.
[0028]
Examples of the configuration of the kneading disc include (1) a kneading disc in which a plurality of discs are configured with a right-hand twist θ °, and (2) a kneading disc configured with a left-hand twist θ °, (3) A single kneading disk or the like is included, and the value of θ includes, for example, 15 °, 30 °, and 45 °.
[0029]
It is preferable that the length of each kneading disk portion is 3 times or less with respect to the inner diameter of the barrel, and the total length of the kneading disk portions is 8 times or less with respect to the inner diameter of the barrel. By setting the length of the kneading disk portion at one place to 3 times or less with respect to the inner diameter of the barrel, it is possible to avoid the occurrence of excessive continuous heat generation in the material to be kneaded. If it is 3 times or more, the outgas generation amount increases, which is not preferable. Also, avoiding excessive shearing heat generation history in the material to be kneaded by making the total length of each kneading disk portion provided at one or more places in the screw to be 8 times or less than the barrel inner diameter. Can do. If it is 8 times or more, the outgas generation amount increases, which is not preferable.
[0030]
By ensuring the above conditions, it is possible to achieve reliable and uniform kneading and to avoid local generation and excessive accumulation of shear heat in the entire material to be kneaded. A sufficient discharge amount can be obtained.
[0031]
In the present invention, it is preferable that the water content of the liquid crystal polyester charged into the hopper of the kneader is 500 ppm or less to suppress the influence of water when shearing heat is generated. When the water content is more than 500 ppm, the liquid crystal polyester may be decomposed in the melting step, and blister resistance may be deteriorated. The moisture level is obtained, for example, by leaving the liquid crystalline polyester in a dry heat oven set at 150 ° C. for 1 hour or longer, or by drying the liquid crystalline polyester with a hopper dryer set at 150 ° C. for 1 hour or longer. be able to. However, a drying step is not necessarily required as long as it can be maintained at 500 ppm or less.
[0032]
In the present invention, 50% by weight or more of the liquid crystalline polyester charged into the hopper of the kneader is used as a powder to reduce the pellet content, and when the shear heat generation occurs, only the pellet surface melts and the slip phenomenon or the pellet is generated. It is preferable to suppress the occurrence of shear fracture. These may hinder uniform melt-kneading of the material to be kneaded and may deteriorate the blister resistance. The particle size level of the powdered liquid crystal polyester is sufficient to suppress the occurrence of the above phenomenon, and is sufficient if the pellets are pulverized, but it is preferably a 20 mesh passing level.
[0033]
The filler is preferably side-fed from one or more locations in the kneader. It is preferable to add a fibrous filler such as glass fiber or carbon fiber in a state where the polymer is sufficiently plasticized in order to avoid cutting of the fiber.
[0034]
In order to improve practical properties, the liquid crystal polyester composition of the present invention includes organic fillers, various conventionally known stabilizers, antioxidants, ultraviolet absorbers, pigments, dyes, modified materials in addition to inorganic fillers. A quality agent or the like may be added. In particular, a phosphite ester having excellent thermal stability represented by the following formula (1), particularly preferably one or more having a melting point of 230 ° C. or higher in consideration of the deflection temperature under load of the resin composition Addition of 0.01 to 1 part by weight is effective as a countermeasure against oxidative deterioration in shearing heat generation of thermal energy for melting the liquid crystal polyester.
[Chemical 3]

[0035]
As a specific compound, cyclic neopentatril bis (2,4-di-tert-butylphenyl) phosphite (Adeka Stub PEP-24G, melting point 170 ° C .: manufactured by Asahi Denka Co., Ltd. is available from the market. ) And cyclic neopentatril bis (2,6-di-tert-butylphenyl) phosphite (Adeka Stub PEP-36, melting point 237 ° C .: available from Asahi Denka Co., Ltd. is available from the market).
[0036]
【The invention's effect】
According to the method of the present invention, when a liquid crystal polyester and an inorganic filler are kneaded, a low outgassing liquid crystal polyester composition in which generation of outgas is reduced by using a biaxial kneader having a screw meshing ratio of 1.6 or more. Is obtained.
[0037]
【Example】
Hereinafter, it demonstrates concretely by an Example and a comparative example.
<Synthesis of liquid crystal polyester>
Liquid crystal polyester was synthesized as follows.
Synthesis of liquid crystal polyester A:
110L g of p-hydroxybenzoic acid, 744.8 g (4.00 mol) of terephthalic acid, 4,4 'in a 6 L polymerization tank (manufactured by Nitto Koatsu Co., Ltd.) made of SUS316 and having a double helical stirring blade. -664.5 g (4.00 mol) of dihydroxybiphenyl was charged, and after depressurization-nitrogen injection of the polymerization tank to perform nitrogen substitution twice, 1731.4 g (16.96 mol) of acetic anhydride was added, and the stirring blade The temperature was raised to 150 ° C. for 1 hour at a rotational speed of 100 rpm, and an acetylation reaction was carried out for 2 hours in a reflux state. After completion of the acetylation, the acetic acid was distilled off, the temperature was raised at 0.5 ° C./min, and the polymer was taken out from the outlet at the bottom of the polymerization tank at 330 ° C. The taken out polymer was pulverized to 20 mesh or less by a pulverizer. Next, solid phase polymerization was performed with a heating device (manufactured by Asahi Glass Works Co., Ltd.) having a cylindrical rotary reactor. The pulverized polymer is put into a cylindrical rotary reactor, nitrogen is circulated at a rate of 1 liter / minute, the temperature is increased to 280 ° C. over 2 hours at a rotation speed of 20 rpm, and maintained at 280 ° C. for 3 hours, and then up to 300 ° C. The temperature was raised in 30 minutes and held for 3 hours, heated to 320 ° C. in 30 minutes and held for 3 hours, further heated to 340 ° C. in 30 minutes and held for 2 hours, and then to room temperature in 1 hour. Cooling gave a polymer. When the melting point of the obtained polymer was measured by DSC, the melting point was 410 ° C. The apparent viscosity at 440 ° C. was 2500 poise.
[0038]
Synthesis of liquid crystal polyester B:
In a 6 L polymerization tank (manufactured by Nitto Koatsu Co., Ltd.) made of SUS316 and having a double helical stirring blade, 1330.1 g (9.63 mol) of p-hydroxybenzoic acid, 133.4 g (0.803 mol) of isophthalic acid, 400. 0 g (2.408 mol) and 4,4′-dihydroxybiphenyl 597.7 g (3.21 mol) were charged, and after depressurization-nitrogen injection into the polymerization tank twice to perform nitrogen substitution, 1736.9 g of acetic anhydride ( 17.01 mol) was added, the temperature was raised to 150 ° C. over 1 hour at a rotation speed of the stirring blade of 100 rpm, and the acetylation reaction was carried out for 2 hours under reflux. After completion of acetylation, acetic acid was distilled off, the temperature was raised at 0.5 ° C./min, and the polymer was taken out from the outlet at the bottom of the polymerization tank at 320 ° C. The taken out polymer was pulverized to 20 mesh or less by a pulverizer. Next, solid phase polymerization was performed with a heating device (manufactured by Asahi Glass Works Co., Ltd.) having a cylindrical rotary reactor. The pulverized polymer is put into a cylindrical rotary reactor, nitrogen is circulated at a rate of 1 liter / min, the temperature is increased to 290 ° C. over 2 hours at a rotation speed of 20 rpm, and the temperature is maintained at 290 ° C. for 6 hours. The polymer was obtained by cooling with time. When the melting point of the obtained polymer was measured by DSC, the melting point was 358 ° C. The apparent viscosity at 370 ° C. was 910 poise.
[0039]
Materials to be kneaded I to III having the following composition were used.
Materials to be kneaded I:
(1) Liquid crystal polyester: Liquid crystal polyester A 60 wt%
(2) Inorganic filler: ground glass fiber (trade name “MF-20JMH1-20, manufactured by Asahi Fiber Glass Co., Ltd.) 40 wt%
Materials to be kneaded II:
(1) Liquid crystalline polyester: Liquid crystalline polyester B 60wt%
(2) Inorganic filler: ground glass fiber (trade name “MF-20JMH1-20, manufactured by Asahi Fiber Glass Co., Ltd.) 20 wt% and glass fiber (trade name“ PX-1 ”, manufactured by Asahi Fiber Glass Co., Ltd.) 20 wt%
Materials to be mixed III:
(1) Liquid crystalline polyester: Liquid crystalline polyester B 60wt%
(2) Inorganic filler: ground glass fiber (trade name “MF-20JMH1-20”, manufactured by Asahi Fiber Glass Co., Ltd.) 20 wt% and glass fiber (trade name “PX-1”, manufactured by Asahi Fiber Glass Co., Ltd.) 20 wt%
(3) Antioxidant: Cyclic neopentatril bis (2,6-di-tert-butylphenyl) phosphite (ADK STAB PEP-36: manufactured by Asahi Denka Co., Ltd.) 0.1 parts by weight
[0040]
In the materials to be kneaded I to III described above, those in which the ratio of liquid crystal polyester pellets and powder and the water content were changed were used. The moisture measurement was performed by the heating loss method according to JIS-K5101. Remove the lid of a flat weighing bottle with a nominal size of 50 x 30 mm and dry it with a dryer kept at 105 ° C for 2 hours. After drying, the balance bottle is allowed to cool to room temperature in a desiccator, and the weighing bottle is covered. The mass was measured to the order of 1 mg. A 20 g sample was weighed into this scale bottle to the nearest 1 mg, capped, and weighed again. Remove the lid of the weighing bottle and dry the weighing bottle with the sample at 105 ° C for 2 hours. After drying, the weighing bottle is allowed to cool to room temperature in a desiccator and the weighing bottle is covered. The mass was measured to the order of 1 mg. And the heating loss was computed from the mass before and behind a heating.
[0041]
The treatment conditions for the two types of kneaders used and the materials to be kneaded were as follows. <Melt-kneader A> Used in Examples 1-12.
Screw meshing rate: 1.62
Barrel dimensions: 46mm inner diameter, L / D = 36
Screw rotation speed: 300rpm
Temperature conditions for the material to be kneaded I:
Barrel temperature: C1: 380 ° C, C2: 410 ° C, C3: 410 ° C, C4: 410 ° C, C5: 410 ° C, C6: 410 ° C, C7: 390 ° C, C8: 370 ° C, C9: 370 ° C
Head temperature: 410 ° C
Die temperature: 410 ° C.
Temperature conditions for materials to be kneaded II and III:
Barrel temperature: C1: 300 ° C, C2: 320 ° C, C3: 350 ° C, C4: 370 ° C, C5: 370 ° C, C6: 370 ° C, C7: 350 ° C, C8: 330 ° C, C9: 330 ° C
Head temperature: 350 ° C.
Die temperature: 350 ° C.
[0042]
<Melt-kneader B> Used in Comparative Examples 1-6.
Screw meshing rate: 1.55
Barrel dimensions: 46mm inner diameter, L / D = 36
Screw rotation speed: 300rpm
Temperature conditions for material to be kneaded I:
Barrel temperature: C1: 380 ° C, C2: 410 ° C, C3: 410 ° C, C4: 410 ° C, C5: 410 ° C, C6: 410 ° C, C7: 390 ° C, C8: 370 ° C, C9: 370 ° C
Head temperature: 410 ° C.
Die temperature: 410 ° C.
Temperature conditions for materials to be kneaded II and III:
Barrel temperature: C1: 300 ° C, C2: 320 ° C, C3: 350 ° C, C4: 370 ° C, C5: 370 ° C, C6: 370 ° C, C7: 350 ° C, C8: 330 ° C, C9: 330 ° C
Head temperature: 350 ° C.
Die temperature: 350 ° C.
[0043]
Note that the screw structures of the kneader A and the kneader B are both a pair of same-direction rotating screws, the kneading disk portion has a length not more than three times the inner diameter of the barrel, and the total length is 8 The ratio was substantially the same except for the meshing rate.
[0044]
<Production of liquid crystal polyester composition>
The materials to be kneaded I to III were melt-kneaded by melt kneaders A and B, respectively, and the strands obtained by extrusion from the dies were cut with a pelletizer to obtain liquid crystal polyester composition pellets.
[0045]
<Manufacture of test specimen for measuring deflection temperature under load>
The liquid crystal polyester composition pellets obtained as described above were put into a hopper of an injection molding machine and injection molded under the following conditions. In addition, the test piece shape of load deflection temperature used the thing based on ASTM648.
Injection molding machine: Sumitomo Heavy Industries, Ltd .: SG-25, mold clamping pressure: 25 tons
Molding conditions for material to be kneaded I:
Barrel temperature: C1: 370 ° C, C2: 400 ° C, C3: 410 ° C
Nozzle temperature: 410 ° C
Mold temperature: 150 ° C
Injection speed: 100mm / sec
Molding conditions of materials to be kneaded II and III:
Barrel temperature: C1: 310 ° C, C2: 340 ° C, C3: 350 ° C
Nozzle temperature: 350 ° C
Mold temperature: 80 ℃
Injection speed: 100mm / sec
[0046]
(Measurement of deflection temperature under load and outgas)
Deflection temperature under load: Conforms to ASTM648. Since the displacement was less than the specified value at 250 ° C., it was confirmed that both were above 250 ° C., and the measurement was terminated at that time.
Outgas: The injection-molded ASTM648 specimen was pulverized by a 1 mmφ mesh pulverizer, and the obtained pulverized product was sealed in a 20 ml vial, and then heat treated at 150 ° C. for 24 hours. The generated acetic acid and phenol gases were quantified by gas chromatography (HP6890) connected to a headspace sampler (HP7694) manufactured by Hewlett Packard. The column is G-100 (40 m) manufactured by the Chemicals Inspection Association. Other conditions are an initial temperature of 45 ° C., a heating rate of 20 ° C./min, a final temperature of 280 ° C., a helium pressure of 8.3 psi, and a split ratio of 2 As 0.0, measurement was performed using an FID detector.
[0047]
The results are shown in Tables 1-3.
[0048]
[Table 1]

[0049]
[Table 2]

[0050]
[Table 3]

[0051]
As shown in Tables 1, 2, and 3, the liquid crystal polyester resin compositions (Examples) produced according to the present invention produced less outgas than the comparative examples.

Claims (5)

Monomer group containing 80 mol% or more of p-hydroxybenzoic acid, terephthalic acid, 4,4′-dihydroxybiphenyl (including these derivatives), acylation and / or monomer of at least part of hydroxyl groups in these monomer groups Volatile components are removed from the material to be kneaded by 90 to 40 wt% of the liquid crystalline polyester having a melting point of 320 ° C. or higher and 10 to 60 wt% of the inorganic filler formed by polycondensing after at least a part of the carboxyl groups in the group is phenylesterified In a method for producing a liquid crystal polyester composition having a deflection temperature under load of 230 ° C. or higher obtained by melt-kneading with a kneader having an opening for the purpose and a pair of two-thread screws, the screw meshing rate of the kneader is 1.60 or more. A method for producing a low outgassing liquid crystal polyester composition, characterized in that: The method for producing a low outgassing liquid crystal polyester composition according to claim 1, wherein the acylation is acetylation using acetic acid or acetic anhydride. The method for producing a low outgassing liquid crystal polyester composition according to any one of claims 1 and 2, wherein the liquid crystal polyester contained in the hopper of the kneader has a water content of 500 ppm or less. The method for producing a low outgassing liquid crystal polyester composition according to any one of claims 1 to 3, wherein 50 wt% or more of the liquid crystal polyester charged into a hopper of the kneader is a powder. The low outgassing liquid crystal polyester according to any one of claims 1 to 4, wherein 0.01 to 1 part by weight of one or more phosphites represented by the formula (1) is added. A method for producing the composition.