JP3655464B2 - Polymer film, method for producing the same, and laminate - Google Patents

Description

【００１０】
（２）芳香族または脂肪族ジカルボン酸（代表例は表２参照）
【００１１】
【表２】

【００１２】
（３）芳香族ヒドロキシカルボン酸（代表例は表３参照）
【００１３】
【表３】

【００１４】
（４）芳香族ジアミン、芳香族ヒドロキシアミンまたは芳香族アミノカルボン酸（代表例は表４参照）
【００１５】
【表４】

【００１６】
（５）これらの化合物から得られる液晶ポリマーの代表例として表５に示す構造単位を有する共重合体（ａ）〜（ｅ）を挙げることができる。
【００１７】
【表５】

【００１８】
これらの液晶ポリマーは、フィルムの耐熱性、加工性の点で２００〜４００℃、特に２５０〜３５０℃の範囲内に光学的異方性の溶融相への転移温度を有するものが好ましい。また、本発明の効果が失われない範囲内、つまりフィルムとしての物性を損なわない範囲内で、滑剤、酸化防止剤、充填材等を配合してもよい。
【００１９】
本発明者等の検討結果では、上記液晶ポリマーのフィルム化にあたっては、ポリマーの流れ開始温度Ｔflowより１０℃以上高い温度で、かつ剪断速度が５００sec^-1以上となるようにダイから製膜する必要がある。この条件を外れると、分子の配向が不十分なため、前記の熱処理で、目的とする高耐熱、高強度のフィルムが得られ難くなる。ここで、流れ開始温度Ｔflowとは、重合体が一定荷重下で流れを開始する温度であり、例えば高化式フローテスターで容易に測定できる。
【００２０】
また、剪断速度（γ）とは、次式により定義される。
γ＝６Ｑ／π（Ｒｏ＋Ｒ _ｉ ）Ｈ²ρ
ここで、
Ｑ：液晶ポリマーの吐出量（ｇ／ｓｅｃ）
Ｒｏ：環状の成形ダイスリットの外周半径 （ｃｍ）
Ｒｉ：環状の成形ダイスリットの内周半径 （ｃｍ）
Ｈ：成形ダイスリット間隔＝Ｒｏ−Ｒｉ （ｃｍ）
ρ：液晶ポリマーの密度 （ｇ／ｃｍ³）である。
【００２１】
本発明の液晶ポリマーフィルムは、光学的異方性の溶融相を形成し得るポリマーを押出成形して得られる。その押出成形には、任意の方法が採用できるが、周知のＴダイ法、インフレーション法等を採用するのが工業的に有利である。特にインフレーション法では、フィルムの機械軸方向（以下、ＭＤ方向と略す）だけでなく、これと直交する方向（以下、ＴＤ方向と略す）にも応力が加わり、ＭＤ方向とＴＤ方向との間における機械的性質および熱的性質のバランスのとれたフィルムを得ることができる。
【００２２】
液晶ポリマーフィルムの厚みとしては、５００μｍ以下が好ましく、特に１０〜２５０μｍがより好ましい。
【００２３】
また本発明では、フィルムを熱処理するにあたって、不活性雰囲気下での熱処理と、それに引き続く活性雰囲気下での熱処理を組み合わせて行う。これにより、目的とするフィルム物性が得られる。
【００２４】
つまり、不活性雰囲気下では、フィルムのＴAがＴm より１０℃高い温度に到達するまで、フィルムの強度が初期値の１．３倍を越えないように、Ｔ m よりも低い温度でフィルムの熱処理を行う。この不活性雰囲気下では、１０℃程度のＴAの増加は、比較的短時間で行われるので、不活性ガスの使用量が少なくてすむが、本発明が目的とするフィブリル化の防止や耐摩耗性の改善が得られない。しかも、フィルムの強度を初期値の１．３倍以上とすると、次の活性雰囲気下での酸化架橋反応が十分進行しなくなるので、フィブリル化の防止や耐摩耗性の改善が期待できなくなる。
【００２５】
上記の不活性雰囲気下とは、窒素、アルゴン等の不活性ガス中あるいは減圧下を意味し、酸素等の活性ガスが０．１体積％以下であることを言う。特に、不活性ガスとしては、純度９９．９％以上の加熱窒素気体が好適に用いられる。
【００２６】
そして、上記の不活性雰囲気下で熱処理を行った後、直ちに（処理温度をあまり低下させず）活性雰囲気中で熱処理を行う。このとき、最終的にフィルムのＴAがＴmよりも１０℃以上高くなるようにすることが、製造コスト及び得られるフィルムの物性上必要である。また、フィルムの重合体の流れ開始温度Ｔflowは、熱処理により漸進的に上昇するので、活性雰囲気下において、熱処理前のＴflowより高い温度で熱処理しても、形態不良は発生しない。
【００２７】
上記の活性雰囲気とは、酸素等の活性ガスを１％以上含んでいる活性ガス含有気体を言い、特に１０％以上の酸素含有気体が好適に用いられる。かかる気体として空気を用いることがコスト的に最も有利である。
【００２８】
上記Ｔm とは、熱処理前のフィルムを、示差走査熱量計（ＤＳＣ）を用いて、窒素雰囲気中５℃／分の速度で４００℃まで昇温し、ついで５０℃／分の速度で室温まで降温し、さらに５℃／分の速度で昇温したとき現われる融解ピークの温度である。
【００２９】
上記ＴA とは、フィルムをＤＳＣを用いて、窒素雰囲気中５℃／分の速度で昇温し、この時に現われる融解ピークの温度である。
【００３０】
また熱処理時に、水分が存在すると、加水分解反応がおこるので、活性雰囲気下での熱処理時には、−４０℃以下の露点をもつ乾燥空気が好適に用いられる。これを使用すれば、高耐熱、高強度で、フィブリル化が起こらず耐摩耗性に優れたフィルムが低コストで得られる。かかる低露点の乾燥空気は、例えばモレキュラーシーブスを用いることにより容易に得られる。
【００３１】
以上の熱処理は、目的により緊張下あるいは無緊張下で行うことができる。また、その熱処理は、ロール状（すきまを設けて触れあうことを防止する）、カセ状（ガス透過性の良好なスペーサーをともに巻く）やトウ状（金網等に乗せる）で行ってもよいし、あるいはローラーを用いて連続的に行ってもよい。
【００３２】
本発明の大きな利点は、高価な不活性ガスの使用量が少なくてすむため、不活性ガスの再使用を行わなくとも工業的に十分成立することである。また、複雑な回収装置が不要であり、しかも副生成物の除去作業も不要となるので、コストメリットが大きい。
【００３３】
以上の方法によって得られたフィルムは、優れた耐熱性と強度を保持し、かつフィブリル化が起こり難く、耐摩耗性に優れている。しかも、活性雰囲気下で熱処理するにもかかわらず着色しない。
【００３４】
上記のポリマーフィルムは、熱処理によりその融点（耐熱性）を任意に調節できる。つまり、上記フィルムの融解ピーク温度ＴAに対し、フィルムの熱処理温度を（ＴA−２０℃）以下とし、該熱処理により増加したフィルムの融点に応じて該熱処理温度を増加させる。このようにすれば、同一化学組成のフィルムを用いてその耐熱性を変えることができるので、フィルムを多層に積層して多層積層板を作製するような場合に、各フィルムの熱圧着による接着一体化が確実に行える。この結果、液晶ポリマーフィルムが本来有する高強力と高弾性率を有し、また耐熱性と耐薬品性に優れ、しかも加工工程や製品後の環境変化により剥離することもなく、長期的に安定使用が可能な多層積層板が得られる。
【００３５】
また、上記のポリマーフィルムに被着体を熱圧着することで積層体が得られるため、上記のポリマーフィルムは、金属箔やガラスなどの被着体を熱圧着して使用される。このとき、熱圧着により発生するフィルムの流れをなくし、かつフィルムと被着体間の接着強度を高めるためには、フィルムの流れを熱圧着前に対し１０重量％以下（好ましくは５重量％以下）とし、被着体との接着強度を０．５Ｋｇ／ｃｍ以上とする。つまり、一般的にＦＰＣ（フレキシブルプリント配線板）やガラス強化樹脂積層板を製造する場合、熱硬化性樹脂板や熱可塑性樹脂板と被着体を熱圧着するとき、１０〜２０重量％の樹脂流れ出しが発生することがある。この流れ出した樹脂は製品を汚染するので、製品から汚れを除去するためには非常に多くの労力を要し、各社個々の技術により努力しているのが現状である。しかし、以上のようにすれば、熱圧着時に樹脂流れ出しがほとんど発生しないので、後処理が簡単となって良好な製品が生産性よく得られる。また、被着体との接着強度を０．５Ｋｇ／ｃｍ以上とすることにより、フィルムと被着体間の接着強度が実用に耐え得る十分な強度にまで高められる。
【００３６】
【実施例】
以下、本発明を具体的な実施例を挙げて説明する。但し、本発明は以下の実施例によって限定されるものではない。
（Ａ）先ず、下記実施例１〜５と比較例１〜５において、共通に使用する液晶ポリマーフィルムを次のようにして製膜した。
６−ヒドロキシ−２−ナフトエ酸単位２７モル％、ｐ−ヒドロキシ安息香酸単位７３モル％からなり、高化式フローテスターで圧力５０Ｋｇ／ｃｍ² で測定した流れ開始温度Ｔflowが２５０℃であるサーモトロピック液晶ポリエステルを、単軸押出機を用いて２８０〜３００℃で加熱混練し、直径４０ｍｍ、スリット間隔０．６ｍｍのインフレーションダイより、剪断速度５５０sec ^-1で押出し、厚さ３０μｍの液晶ポリマーフィルムを得た。この加熱未処理のフィルムについて、ＤＳＣを用いてＴmを測定したところ２８０℃であった。また、強度は３９．７Ｋｇ／ｍｍ²であった。なお、同フィルムは、着色はないものの、フィブリル化が発生する。
【００３７】
（Ｂ）実施例１〜３および比較例１〜３での熱処理は、何れも次のような共通条件でプログラムコントロールにより行った。
（１）気体を１８０℃に予熱して試料を仕込む。
（２）１８０℃から２４０℃までの昇温を１時間で行う。
（３）２４０℃から２６０℃までの昇温を１時間で行う。
（４）２６０℃から２７５℃までの昇温を２時間で行う。
（５）２７５℃から２８５℃までの昇温を６時間で行う。
（６）２８５℃から１８０℃までの降温を１時間で行う。
このときの気体の流量は、何れも０．３Ｎｍ³ ／ｍｉｎである。
【００３８】
実施例１
上記（Ａ）のフィルムを上記（Ｂ）の（１）〜（４）まで９９．９％の窒素ガス中で熱処理し、その後（５）および（６）については乾燥空気中（露点−６０℃）で熱処理を行った。このとき、（１）〜（４）の処理により得られたフィルムの強度は、５０Ｋｇ／ｍｍ²、ＴAは３００℃であった。また（６）までの熱処理を行ったフィルムについて、フィブリル化、着色、ＴA、強度を調べた結果は、表６に示す通りである。
【００３９】
実施例２
上記（Ｂ）の（１）〜（４）まで９９．９％の窒素ガス中で熱処理し、その後（５）および（６）については２体積％の酸素を含有する窒素ガス中で熱処理した。得られたフィルムについて、実施例１と同様に諸性能を調べた結果を表６に示す。
【００４０】
実施例３
上記（Ａ）のフィルムと支持体としてのアルミ箔（厚さ５０μｍ）とをともに巻き、実施例２と同様に処理した。得られたフィルムについて、実施例１と同様に諸性能を調べた結果を表６に示す。
【００４１】
比較例１
上記（Ａ）のフィルムを上記（Ｂ）の（１）〜（６）まで９９．９％の窒素ガス中で熱処理した。なお、熱処理中の窒素ガス使用量は、製品１ｋｇ当り３３Ｎｍ ^３ である。得られたフィルムについて、実施例１と同様に諸性能を調べた結果を表６に示す。
【００４２】
比較例２
上記（Ａ）のフィルムを上記（Ｂ）の（１）〜（４）、および（５）の２時間まで９９．９％の窒素ガス中で熱処理した。このときのフィルムの強度は、６０Ｋｇ／ｍｍ²、ＴAは３１０℃であった。その後（５）および（６）については、乾燥空気中（露点−６０℃）で熱処理を行った。得られたフィルムについて、実施例１と同様に諸性能を調べた結果を表６に示す。
【００４３】
比較例３
上記（Ａ）のフィルムを上記（Ｂ）の（１）〜（６）まで乾燥空気中（露点−６０℃）で熱処理を行った。得られたフィルムについて、実施例１と同様に諸性能を調べた結果を表６に示す。
【００４４】
上記フィブリル化は、フィルムの表面に、表面を布で覆った１０ｍｍ×１５ｍｍの大きさの摩耗子を乗せ、５００ｇの荷重を負荷しながら、３０ｍｍの距離を往復して１時間連続走査し、摩耗子に付着するフィブリルの量により評価した。そして、フィブリル量が多いものを×、全くでないものを○、中間を△として、表６に示している。
【００４５】
上記フィルムの強度とは、引張り試験機を用いて、ＪＩＳ Ｃ ２３１８に準じて測定したものである。
【００４６】
【表６】

【００４７】
上記表６から明らかなように、実施例１〜３によれば、フィブリル化および着色が発生せず、また強度の高いフィルムが得られる。一方、比較例１〜３によればフィブリル化が発生し、しかも比較例３では強度の増加が少なく着色が発生する。また、比較例１によれば、実施例と同等の性能が得られるものの、製品１ｋｇ当り３３Ｎｍ ^３ というように多量の窒素ガスを必要とするので、コストの増大を招く。
【００４８】
また、前述のとおり、以上のポリマーフィルムは、熱処理によりその融点（耐熱性）を任意に調節できる。つまり、上記フィルムの融解ピーク温度ＴAに対し、フィルムの熱処理温度をＴA−２０℃とし、熱処理により増加したフィルムのＴAに応じて該熱処理温度を増加させるのが好ましい。さらに、前述のとおり、以上のポリマーフィルムは、金属箔やガラスなどの被着体を熱圧着して使用される。このとき、熱圧着により発生するフィルムの流れによる製品の汚れをなくし、かつフィルムと被着体との密着性を確保するためには、フィルムの流れを熱圧着前に対し１０％以下とし、被着体との接着強度を０．５Ｋｇ／ｃｍ以上とするのが好ましい。その具体例を実施例により説明する。
【００４９】
実施例４
（Ｃ）先ず、上記（Ａ）で得られたフィルムについて、熱処理温度を設定するために、熱処理中のフィルムの融点ＴAの変化を以下の方法で測定した。次のような熱処理条件をプログラムコントロールにより行った。
（１）９９．９％の窒素ガスを１８０℃に予熱して試料を仕込む。
（２）１８０℃から２６０℃までの昇温を１時間で行う。
（３）２６０℃の一定温度で４時間にわたり熱処理するが、１時間単位でフィルムを取り出してフィルムの融点ＴAを測定する。
（４）フィルムの取り出し前には、２６０℃から１８０℃までの降温を１時間で行う。
この時の気体の流量は、０．３Ｎｍ³ ／ｍｉｎである。フィルムのＴAは上記（３）の条件が、１時間の時には２８５℃、２時間の時には２９６℃、４時間の時には３０６℃に変化していた。
（Ｄ）ついで、上記（３）の条件を２６０℃で１時間の熱処理後、熱処理温度を２６５℃にして１時間、さらに２７５℃にして２時間の合計４時間の熱処理条件に変更して、熱処理を施したフィルムを作製した。得られたフィルムのＴAは３１５℃であった。
上記フィルムを直径１０ｃｍの円形に切断した後、同様なサイズの厚さ１８μｍの電解銅箔２枚で挟み、真空熱圧着機により熱接着した。この熱接着は、圧着熱板の周囲を４０ｍｍ水銀柱以下の真空状態とした中で、圧着熱板により温度３０５℃で１０分間、３０Ｋｇ／ｃｍ² の圧力に保持して行った。このときの樹脂の流れ出し量と、銅箔とフィルムの接着強度を測定した結果は、表７に示す通りである。
【００５０】
実施例５
上記（Ｄ）のフィルムを使用し、熱圧着温度を３２５℃とした以外は実施例４と同様な条件下で銅箔と熱接着した。これについて、実施例４と同様の評価を行った結果は、表７の通りである。
【００５１】
比較例４
上記（Ａ）のフィルムを、熱処理することなく、そのまま熱圧着温度を２７０℃とした以外は実施例４と同様な方法で銅箔と熱接着した。これについて、実施例４と同様の評価を行った結果は、表７の通りである。
【００５２】
比較例５
上記（Ａ）のフィルムを、熱処理することなく、そのまま熱圧着温度を２９０℃とした以外は、実施例４と同様な方法で銅箔と熱接着した。これについて、実施例４と同様の評価を行った結果は、表７の通りである。
【００５３】
表７中、樹脂流れ出し量は、フィルムから銅箔を塩化第二鉄溶液で除去し、熱接着前のサイズ（直径１０ｃｍ）に対する樹脂はみ出し量を測定した。はみ出し量は重量％に換算し、指標とした。
【００５４】
また、接着強度は、１．５ｃｍ幅の剥離試験片を作成し、そのフィルム層を両面接着テープで平板に固定し、ＪＩＳ Ｃ ５０１６に準じ、１８０゜法により銅箔部を５０ｍｍ／分の速度で剥離したときの強度を測定した。
【００５５】
【表７】

【００５６】
上記表７から明らかなように、実施例４および５によれば、樹脂流れ出し量が５％以下で、また接着強度も１．０Ｋｇ／ｃｍ以上と強い。一方、比較例４によれば、樹脂流れ出し量が実施例４および５と同等になるが、接着強度が０．４Ｋｇ／ｃｍとなって弱くなる。また、比較例５によれば、実施例４および５と同等の接着強度が得られるものの、樹脂流れ量が大きくなる。
【００５７】
【発明の効果】
本発明によれば、低コストで製造可能で、高度の耐熱性や強度を保持し、かつフィブリル化が起こり難く、耐摩耗性に優れた液晶ポリマーフィルムを得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention is a polymer capable of forming a melt phase of optically anisotropic adherend thermocompression bonding the film to consist (hereinafter sometimes referred to as "liquid crystal polymer") films and their production side Honami beauty It is related with the laminated body formed.
[0002]
[Prior art]
In recent years, demand for FPCs (flexible printed wiring boards) has been increasing due to demands for smaller and lighter devices in the field of electronics and electrical industries. The general manufacturing method of this FPC forms an electric circuit after laminating | stacking metal foil, such as copper foil, on at least one surface of a base film. A polyethylene terephthalate film or the like is frequently used as the base film. However, since these films have poor heat resistance, inconvenience occurs when the FPC is immersed in a solder bath during component mounting on the FPC. Then, the film which consists of a liquid crystal polymer excellent in heat resistance attracts attention as a base film.
[0003]
By the way, since a liquid crystal polymer generally has high heat resistance (melting point), when forming into a film, it is necessary to increase its molding temperature, which requires a great deal of energy. Some liquid crystal polymers can be molded at a relatively low temperature, but the film obtained therefrom has a low heat resistance and is difficult to use as a heat resistant substrate. Therefore, a method for improving the heat resistance of the film by forming a film using a liquid crystal polymer having a low forming temperature and then heat-treating the film in a nitrogen atmosphere at a temperature not higher than the polymer melting point Tm has been proposed. Yes.
[0004]
[Problems to be solved by the invention]
A film made of a liquid crystal polymer has high strength and high elastic modulus, and also has excellent performance such as heat resistance and chemical resistance. However, in order to obtain sufficient heat resistance to withstand practical use, it is necessary to perform heat treatment for a long time in a nitrogen atmosphere, which increases energy consumption and increases the amount of nitrogen gas used, resulting in increased costs. Become. In addition, the obtained film has a problem that the rigid molecules are highly oriented, so that the film is hard, fibrillation (fuzzing phenomenon generated when rubbing) easily occurs, and wear resistance is poor.
[0005]
As a result of researches on the liquid crystal polymer film having the above excellent features, the present inventors have found the following. In other words, if an inexpensive active gas such as air is used instead of nitrogen gas, the cost will be greatly reduced in terms of facilities and utilities, and heat treatment in the active gas will result in an oxidation reaction. A cross-linking reaction or the like occurs on the film surface, and a film that hardly causes fibrillation can be obtained. However, if heat treatment is performed in an active gas, discoloration (deterioration) of the film and a peaking phenomenon of the strength occur, and the desired high heat-resistant and high-strength film is often not obtained even after long-time treatment. As a result of further research, it was found that the above problems can be solved by improving the film forming method of the liquid crystal polymer and heat-treating the film under special conditions.
Thus, an object of the present invention is to provide a method for producing a liquid crystal polymer film that can be produced at low cost, retains high heat resistance and strength, hardly causes fibrillation, and has excellent wear resistance. is there.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing a polymer film of the present invention comprises a polymer capable of forming an optically anisotropic melt phase at a temperature higher than the flow start temperature Tflow of the polymer by 10 ° C. or more and a shear rate. Is formed from a die under the condition of 500 sec ⁻¹ or more, and the film is processed during measurement when the formed film is measured at a heating rate of 5 ° C./min in a nitrogen atmosphere with a differential scanning calorimeter. melting peak temperature TA is, until reaching 10 ° C. higher than the melting point Tm before the heat treatment of the film, and the melting point the intensity is under an inert atmosphere so as not to exceed 1.3 times the initial value of the film Heat treatment is performed at a temperature lower than T m , and then heat treatment is performed in an active atmosphere so that the melting peak temperature TA is higher by 10 ° C. than the melting point Tm.
[0007]
Specific examples of the liquid crystal polymer used in the present invention include known thermotropic liquid crystal polyesters and thermotropic liquid crystal polyester amides derived from the compounds classified in (1) to (4) and derivatives thereof exemplified below. it can. However, it goes without saying that a suitable combination of repeating units is required to obtain a polymer capable of forming an optically anisotropic melt phase.
[0008]
(1) Aromatic or aliphatic dihydroxy compounds (see Table 1 for typical examples)
[0009]
[Table 1]

[0010]
(2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for typical examples)
[0011]
[Table 2]

[0012]
(3) Aromatic hydroxycarboxylic acids (see Table 3 for typical examples)
[0013]
[Table 3]

[0014]
(4) Aromatic diamine, aromatic hydroxyamine or aromatic aminocarboxylic acid (see Table 4 for typical examples)
[0015]
[Table 4]

[0016]
(5) As typical examples of liquid crystal polymers obtained from these compounds, copolymers (a) to (e) having the structural units shown in Table 5 can be mentioned.
[0017]
[Table 5]

[0018]
These liquid crystal polymers are preferably those having a transition temperature to an optically anisotropic melt phase in the range of 200 to 400 ° C., particularly 250 to 350 ° C., from the viewpoint of heat resistance and workability of the film. Moreover, you may mix | blend a lubricant, antioxidant, a filler, etc. within the range which does not lose the effect of this invention, ie, the range which does not impair the physical property as a film.
[0019]
According to the results of the study by the present inventors, when forming the liquid crystal polymer into a film, it is necessary to form a film from the die so that the temperature is 10 ° C. higher than the polymer flow start temperature Tflow and the shear rate is 500 sec ⁻¹ or higher. There is. If this condition is not satisfied, the orientation of the molecules is insufficient, so that it is difficult to obtain the desired high heat resistance and high strength film by the heat treatment. Here, the flow start temperature Tflow is a temperature at which the polymer starts to flow under a constant load, and can be easily measured by, for example, a Koka flow tester.
[0020]
The shear rate (γ) is defined by the following equation.
γ = 6Q / π (Ro + R _i ) H ² ρ
here,
Q: Discharge amount of liquid crystal polymer (g / sec)
Ro: radius of outer periphery of annular molding die slit (cm)
Ri: Inner radius of the annular molding die slit (cm)
H: Molding die slit interval = Ro-Ri (cm)
ρ: Density of liquid crystal polymer (g / cm ³ ).
[0021]
The liquid crystal polymer film of the present invention is obtained by extrusion molding a polymer capable of forming an optically anisotropic melt phase. Although any method can be adopted for the extrusion, it is industrially advantageous to employ a well-known T-die method, inflation method or the like. In particular, in the inflation method, stress is applied not only in the mechanical axis direction of the film (hereinafter abbreviated as MD direction) but also in the direction orthogonal to this (hereinafter abbreviated as TD direction), and between the MD direction and the TD direction. Films with a balance of mechanical and thermal properties can be obtained.
[0022]
The thickness of the liquid crystal polymer film is preferably 500 μm or less, and more preferably 10 to 250 μm.
[0023]
In the present invention, when heat-treating the film, a heat treatment under an inert atmosphere and a subsequent heat treatment under an active atmosphere are performed in combination. Thereby, the target film physical property is obtained.
[0024]
In other words, in an inert atmosphere , the film is heat-treated at a temperature lower than T m so that the film strength does not exceed 1.3 times the initial value until the film TA reaches 10 ° C. higher than T m. I do. In this inert atmosphere, the increase in TA of about 10 ° C. is performed in a relatively short time, so that the amount of inert gas used can be reduced. The improvement of sex cannot be obtained. In addition, when the strength of the film is 1.3 times or more of the initial value, the oxidation crosslinking reaction under the next active atmosphere does not proceed sufficiently, so that prevention of fibrillation and improvement of wear resistance cannot be expected.
[0025]
The above-mentioned inert atmosphere means in an inert gas such as nitrogen or argon or under reduced pressure, and means that the active gas such as oxygen is 0.1% by volume or less. In particular, as the inert gas, heated nitrogen gas having a purity of 99.9% or more is preferably used.
[0026]
And after heat-processing in said inert atmosphere, it heat-processes in an active atmosphere immediately (it does not reduce processing temperature so much). At this time, it is necessary in view of manufacturing cost and physical properties of the film to be obtained that the TA of the film is finally higher by 10 ° C. or more than Tm. Moreover, since the flow start temperature Tflow of the polymer of the film is gradually increased by the heat treatment, even if the heat treatment is performed at a temperature higher than the Tflow before the heat treatment in the active atmosphere, no form defect occurs.
[0027]
The above active atmosphere refers to an active gas-containing gas containing 1% or more of an active gas such as oxygen, and an oxygen-containing gas of 10% or more is particularly preferably used. Use of air as the gas is most advantageous in terms of cost.
[0028]
The above Tm means that the film before heat treatment is heated to 400 ° C. at a rate of 5 ° C./min in a nitrogen atmosphere using a differential scanning calorimeter (DSC) and then cooled to room temperature at a rate of 50 ° C./min. The temperature of the melting peak that appears when the temperature is further increased at a rate of 5 ° C./min.
[0029]
The TA is the temperature of the melting peak that appears when the film is heated at a rate of 5 ° C./min in a nitrogen atmosphere using DSC.
[0030]
Further, when water is present during the heat treatment, a hydrolysis reaction occurs. Therefore, dry air having a dew point of −40 ° C. or lower is preferably used during the heat treatment in an active atmosphere. By using this, a film having high heat resistance, high strength, no fibrillation and excellent wear resistance can be obtained at low cost. Such low dew point dry air can be easily obtained by using, for example, molecular sieves.
[0031]
The above heat treatment can be performed under tension or without tension depending on the purpose. In addition, the heat treatment may be performed in a roll shape (preventing touching by providing a gap), a casket shape (wound together with a gas-permeable spacer) or a tow shape (mounted on a wire mesh or the like) Or you may carry out continuously using a roller.
[0032]
The great advantage of the present invention is that the amount of expensive inert gas to be used is small, and it is industrially sufficient even if the inert gas is not reused. In addition, a complicated recovery device is not required , and the removal work of by-products is not required , resulting in a large cost merit.
[0033]
The film obtained by the above method retains excellent heat resistance and strength, hardly causes fibrillation, and has excellent wear resistance. Moreover, it is not colored despite being heat-treated in an active atmosphere.
[0034]
The melting point (heat resistance) of the polymer film can be arbitrarily adjusted by heat treatment. That is, the heat treatment temperature of the film is set to (TA-20 ° C.) or lower with respect to the melting peak temperature TA of the film, and the heat treatment temperature is increased according to the melting point of the film increased by the heat treatment. In this way, since the heat resistance can be changed using films of the same chemical composition, when films are laminated in multiple layers to produce a multilayer laminate, each film is bonded by thermocompression bonding. Can be reliably performed. As a result, it has the high strength and high elasticity inherent in liquid crystal polymer films, is excellent in heat resistance and chemical resistance, and does not peel off due to processing processes or environmental changes after the product, and can be used stably over the long term Can be obtained.
[0035]
Moreover, since a laminated body is obtained by thermocompression-bonding an adherend to the polymer film, the polymer film is used by thermocompression-bonding an adherend such as a metal foil or glass. At this time, in order to eliminate the flow of the film generated by thermocompression bonding and to increase the adhesive strength between the film and the adherend, the flow of the film is 10% by weight or less (preferably 5% by weight or less) with respect to that before thermocompression bonding. And the adhesive strength with the adherend is 0.5 kg / cm or more. That is, generally when manufacturing FPC (flexible printed circuit board) and glass reinforced resin laminates, when thermosetting resin plate or thermoplastic resin plate and the adherend are thermocompression bonded, 10-20% by weight of resin Outflow may occur. Since the resin that has flowed out contaminates the product, a great deal of labor is required to remove the dirt from the product, and the current situation is that efforts are made by the technology of each company. However, since the resin flow hardly occurs during the thermocompression bonding as described above, the post-processing is simplified and a good product can be obtained with high productivity. Further, by setting the adhesive strength with the adherend to 0.5 Kg / cm or more, the adhesive strength between the film and the adherend can be increased to a sufficient strength to withstand practical use.
[0036]
【Example】
Hereinafter, the present invention will be described with reference to specific examples. However, the present invention is not limited to the following examples.
(A) First, in Examples 1 to 5 and Comparative Examples 1 to 5 below, a liquid crystal polymer film used in common was formed as follows.
Thermotropic which consists of 27 mol% of 6-hydroxy-2-naphthoic acid units and 73 mol% of p-hydroxybenzoic acid units, and has a flow start temperature Tflow of 250 ° C. measured with a Koka flow tester at a pressure of 50 kg / cm ^2. Liquid crystal polyester is heated and kneaded at 280 to 300 ° C. using a single screw extruder and extruded from an inflation die having a diameter of 40 mm and a slit interval of 0.6 mm at a shear rate of 550 sec ⁻¹ to obtain a liquid crystal polymer film having a thickness of 30 μm. It was. This untreated film was measured for Tm using DSC and found to be 280 ° C. The strength was 39.7 kg / mm ² . In addition, although the film is not colored, fibrillation occurs.
[0037]
(B) The heat treatments in Examples 1 to 3 and Comparative Examples 1 to 3 were all performed by program control under the following common conditions.
(1) Preheat the gas to 180 ° C. and charge the sample.
(2) The temperature is raised from 180 ° C. to 240 ° C. in 1 hour.
(3) The temperature is raised from 240 ° C. to 260 ° C. in 1 hour.
(4) The temperature is raised from 260 ° C. to 275 ° C. in 2 hours.
(5) The temperature is raised from 275 ° C. to 285 ° C. in 6 hours.
(6) The temperature is lowered from 285 ° C. to 180 ° C. in 1 hour.
In this case, the gas flow rate is 0.3 Nm ³ / min.
[0038]
Example 1
The film of (A) was heat-treated in 99.9% nitrogen gas from (1) to (4) of (B), and then (5) and (6) were in dry air (dew point −60 ° C. ) Was heat-treated. At this time, the strength of the film obtained by the treatments (1) to (4) was 50 kg / mm ² , and TA was 300 ° C. Table 6 shows the results of examining the fibrillation, coloring, TA, and strength of the film subjected to the heat treatment up to (6).
[0039]
Example 2
(B) (1) to (4) were heat-treated in 99.9% nitrogen gas, and then (5) and (6) were heat-treated in nitrogen gas containing 2% by volume of oxygen. Table 6 shows the results obtained by examining various performances of the obtained film in the same manner as in Example 1.
[0040]
Example 3
The film of (A) and an aluminum foil (thickness 50 μm) as a support were wound together and treated in the same manner as in Example 2. Table 6 shows the results obtained by examining various performances of the obtained film in the same manner as in Example 1.
[0041]
Comparative Example 1
The film of (A) was heat-treated in 99.9% nitrogen gas from (1) to (6) of (B) above. The amount of nitrogen gas used during the heat treatment is 33 N m ³ per kg of product. Table 6 shows the results obtained by examining various performances of the obtained film in the same manner as in Example 1.
[0042]
Comparative Example 2
The film of (A) was heat-treated in 99.9% nitrogen gas up to 2 hours of (B) (1) to (4) and (5). At this time, the film had a strength of 60 kg / mm ² and a TA of 310 ° C. Thereafter, (5) and (6) were heat-treated in dry air (dew point -60 ° C). Table 6 shows the results obtained by examining various performances of the obtained film in the same manner as in Example 1.
[0043]
Comparative Example 3
The film of (A) was heat-treated in dry air (dew point -60 ° C.) from (1) to (6) of (B). Table 6 shows the results obtained by examining various performances of the obtained film in the same manner as in Example 1.
[0044]
The above-mentioned fibrillation is carried out by placing a 10 mm × 15 mm wear piece whose surface is covered with a cloth on the surface of the film, and continuously scanning for 1 hour by reciprocating a distance of 30 mm while applying a load of 500 g. Evaluation was based on the amount of fibrils adhering to the child. Table 6 shows the case where the amount of fibril is large as x, the case where it is not at all as ◯, and the middle as Δ.
[0045]
The strength of the film is measured according to JIS C 2318 using a tensile tester.
[0046]
[Table 6]

[0047]
As is clear from Table 6 above, according to Examples 1 to 3, fibrillation and coloring do not occur and a film having high strength can be obtained. On the other hand, according to Comparative Examples 1 to 3, fibrillation occurs, and in Comparative Example 3, there is little increase in strength and coloring occurs. In addition, according to Comparative Example 1, although the examples the same performance is obtained, because it requires a large amount of nitrogen gas so that the product 1kg per 33N m ^3, causing an increase in cost.
[0048]
Further, as described above, the melting point (heat resistance) of the above polymer film can be arbitrarily adjusted by heat treatment. That is, it is preferable that the heat treatment temperature of the film is TA-20 ° C. with respect to the melting peak temperature TA of the film, and the heat treatment temperature is increased according to the TA of the film increased by the heat treatment. Furthermore, as described above, the above polymer film is used by thermocompression-bonding an adherend such as a metal foil or glass. At this time, in order to eliminate the contamination of the product due to the film flow generated by thermocompression bonding and to ensure the adhesion between the film and the adherend, the film flow should be 10% or less of that before thermocompression bonding. It is preferable that the adhesive strength with the adherend be 0.5 kg / cm or more. Specific examples thereof will be described with reference to examples.
[0049]
Example 4
(C) First, in order to set the heat treatment temperature for the film obtained in (A) above, the change in the melting point TA of the film during the heat treatment was measured by the following method. The following heat treatment conditions were performed by program control.
(1) A sample is prepared by preheating 99.9% of nitrogen gas to 180 ° C.
(2) The temperature is raised from 180 ° C. to 260 ° C. in 1 hour.
(3) Heat treatment is performed at a constant temperature of 260 ° C. for 4 hours, but the film is taken out in units of 1 hour and the melting point TA of the film is measured.
(4) Before the film is taken out, the temperature is lowered from 260 ° C. to 180 ° C. in 1 hour.
The gas flow rate at this time is 0.3 Nm ³ / min. The TA of the film was changed to 285 ° C. when the condition (3) was 1 hour, 296 ° C. when 2 hours, 306 ° C. when 4 hours, and 306 ° C. when 4 hours.
(D) Next, after the heat treatment at 260 ° C. for 1 hour, the heat treatment temperature was changed to 265 ° C. for 1 hour, and further changed to 275 ° C. for 2 hours. A heat-treated film was produced. The TA of the obtained film was 315 ° C.
The film was cut into a circle having a diameter of 10 cm, sandwiched between two pieces of electrolytic copper foil having a similar size and a thickness of 18 μm, and thermally bonded by a vacuum thermocompression bonding machine. This thermal bonding was performed by maintaining the pressure hot plate at a pressure of 30 kg / cm ² for 10 minutes at a temperature of 305 ° C. in a vacuum state of 40 mm mercury or less around the pressure hot plate. Table 7 shows the measurement results of the resin flow-out amount and the adhesive strength between the copper foil and the film.
[0050]
Example 5
The film of the above (D) was used and thermally bonded to the copper foil under the same conditions as in Example 4 except that the thermocompression bonding temperature was 325 ° C. The results of the same evaluation as in Example 4 are shown in Table 7.
[0051]
Comparative Example 4
The film (A) was thermally bonded to the copper foil in the same manner as in Example 4 except that the thermocompression bonding temperature was set to 270 ° C. as it was without heat treatment. The results of the same evaluation as in Example 4 are shown in Table 7.
[0052]
Comparative Example 5
The film (A) was thermally bonded to the copper foil in the same manner as in Example 4 except that the thermocompression bonding temperature was 290 ° C. without any heat treatment. The results of the same evaluation as in Example 4 are shown in Table 7.
[0053]
In Table 7, as for the resin flow-out amount, the copper foil was removed from the film with a ferric chloride solution, and the resin protrusion amount with respect to the size (diameter 10 cm) before thermal bonding was measured. The amount of protrusion was converted into weight% and used as an index.
[0054]
In addition, the adhesive strength is a 1.5 cm wide peel test piece, the film layer is fixed to a flat plate with a double-sided adhesive tape, and the copper foil part is formed at a speed of 50 mm / min by the 180 ° method according to JIS C 5016. The strength when peeled with was measured.
[0055]
[Table 7]

[0056]
As is apparent from Table 7 above, according to Examples 4 and 5, the resin flow-out amount is 5% or less and the adhesive strength is as strong as 1.0 kg / cm or more. On the other hand, according to Comparative Example 4, the resin flow-out amount is equivalent to that in Examples 4 and 5, but the adhesive strength is weakened to 0.4 kg / cm. Moreover, according to the comparative example 5, although the adhesive strength equivalent to Example 4 and 5 is obtained, the resin flow amount becomes large.
[0057]
【The invention's effect】
According to the present invention, it is possible to obtain a liquid crystal polymer film that can be produced at low cost, retains high heat resistance and strength, hardly causes fibrillation, and has excellent wear resistance.

Claims (7)

A polymer capable of forming an optically anisotropic melt phase is formed from a die at a temperature 10 ° C. or more higher than the flow start temperature Tflow of the polymer and at a shear rate of 500 sec ⁻¹ or more. The melting peak temperature TA of the film during the treatment when this film was measured with a differential scanning calorimeter at a rate of temperature increase of 5 ° C./min in a nitrogen atmosphere was 10 from the melting point Tm before the heat treatment of the film. Until the temperature reaches a high temperature, the film is heat-treated in an inert atmosphere and at a temperature lower than the melting point T m so that the strength of the film does not exceed 1.3 times the initial value. A method for producing a polymer film, wherein heat treatment is performed so that a melting peak temperature TA is higher by 10 ° C. or more than the melting point Tm. The method for producing a polymer film according to claim 1, wherein the inert atmosphere is a heated nitrogen gas having a purity of 99.9% or more, and the active atmosphere is a heated gas containing 1% or more of oxygen. The method for producing a polymer film according to claim 1 or 2, wherein the active atmosphere is dry air having a dew point of -40 ° C or lower. The heat treatment under the active atmosphere according to any one of claims 1 to 3, wherein the heat treatment temperature is set to (TA-20 ° C) or less with respect to the melting peak temperature TA of the film, and the melting point of the film increased by the heat treatment. A method for producing a polymer film, which is performed by sequentially increasing the heat treatment temperature accordingly. The polymer film produced by the method in any one of Claims 1-4. A laminate comprising an adherend and a thermocompression bonded to the polymer film of claim 5. In Claim 6, when an adherend is thermocompression bonded to the film, the flow of the film is 10% by weight or less with respect to that before thermocompression bonding, and the adhesive strength with the adherend is 0.5 Kg / cm or more. Laminated body.