JP4976610B2

JP4976610B2 - Method for producing a long fiber reinforced thermoplastic resin molding

Info

Publication number: JP4976610B2
Application number: JP35498899A
Authority: JP
Inventors: 徹水上; 憲吾尾崎; 秀行東山
Original assignee: オーウェンスコーニング製造株式会社
Priority date: 1998-12-15
Filing date: 1999-12-14
Publication date: 2012-07-18
Anticipated expiration: 2019-12-14
Also published as: JP2000233421A

Description

【０００１】
【発明の属する技術分野】
本発明は、表面外観性や高強度、高剛性が要求される自動車部品や家電製品、産業資材、土木資材などに適した長繊維強化熱可塑性樹脂（以下「ＬＦＲＴＰ」という）成形体の製造方法に関する。
【０００２】
【従来技術】
従来より、ＬＦＲＴＰ成形体の製造方法において、特定の方向に並んだ強化繊維（以下単に「繊維」という）を含有する熱可塑性樹脂を所定形状に切断した約２〜３ｍｍ径のＬＦＲＴＰ基材を加熱溶融させて射出成型法により成形体を製造する方法が知られている。この方法で用いるＬＦＲＴＰ基材は、熱可塑性樹脂と繊維を混練した従来の短繊維強化熱可塑性樹脂基材に比べて、含有されている繊維長が長く、成形体中の繊維長をより長く維持させることが可能であり、また、繊維に熱可塑性樹脂が予め含浸されていることから、これを成形した成形体は機械的強度や表面外観性が優れるものであった。
【０００３】
【発明が解決しようとする課題】
しかしながら、上記方法で用いる繊維長の長いＬＦＲＴＰ基材を用いても、圧縮比の高いスクリューによる混練や射出時の高い圧力により、大きな剪断が加わって成形体中の繊維長が短くなり、結果として成形体の衝撃強度、引っ張り強度などの機械的強度が劣るという問題を有していた。
【０００４】
さらに、前記ＬＦＲＴＰ基材を分散し、これを加熱成形したＬＦＲＴＰ基材シートおよび該シートを加熱溶融後に成形型に導入し、常温または加温プレスして得られる成形体が知られている（特開平９−１０９３１０号公報）。この方法では、一旦予備成形されたＬＦＲＴＰ基材シートを作製すれば、該シートを加熱溶融後に成形型にセットして成形するだけの簡便な方法であり、得られる成形体はその中の繊維長を比較的長く維持し、比較的高強度の成形体を得ることができるものであるが、目的の成形体を得るためには、ＬＦＲＴＰ基材の作製工程、そのシート化工程およびプレス成形工程と三度にわたる熱可塑性樹脂の溶融軟化が必要であり、エネルギー効率的にも、樹脂の熱劣化の点でも問題を有していた。さらに、成形時の流動性を向上させるためにＬＦＲＴＰ基材シート内部まで十分に加熱溶融させると、上記シートが柔らかいために取扱性が劣り、これを複数枚成形型に積層させる通常の流動成形を行うと、作業が煩雑になるという問題を有していた。
従って、本発明の目的は、上記従来の課題を解決し、得られるＬＦＲＴＰ成形体の機械的強度を向上させるものである。
【０００５】
【課題を解決するための手段】
上記目的は、以下の本発明によって達成される。即ち、本発明は、ＬＦＲＴＰ基材を単独または該基材を非強化樹脂で希釈して溶融して溶融物を作成し、該溶融物を成形型に供給してプレス成形するＬＦＲＴＰ成形体の製造方法において、上記ＬＦＲＴＰ基材が、連続繊維ストランド一本または複数本に熱可塑性樹脂を含浸させてノズルから引き抜き、長さ１０〜５０ｍｍに切断した径または厚さ０．０５〜２．５ｍｍ、かつ繊維含有率１５〜８０容量％のＬＦＲＴＰ基材であり、該基材を加熱搬送機で溶融物中の繊維の平均長が元のＬＦＲＴＰ基材長の４０％以上の長さを保持した溶融物を作製し成形することを特徴とするＬＦＲＴＰ成形体の製造方法を提供する。
【０００６】
本発明においては、ＬＦＲＴＰ基材を加熱搬送する際に、溶融物中の繊維の平均長が元のＬＦＲＴＰ基材長の４０％以上の長さを保持した溶融物を作製することで、成形体中の繊維の平均長を長く維持させて成形体の機械的強度を向上させることができる。
【０００７】
また、本発明では加熱工程を伴うシート化を経ることなく成形するため、樹脂の熱劣化を抑えると共に、柔らかくなった溶融シートを複数枚成形型に移動させるという従来技術の煩雑な作業を不要にするものである。
【０００８】
【発明の実施の形態】
次に好ましい実施の形態を挙げて本発明をさらに詳細に説明する。
本発明で使用する熱可塑性樹脂としては、特に限定はなく一般に市販されている種々のものが使用可能である。例えば、ポリオレフィン系樹脂、ポリアミド系樹脂、ポリエステル系樹脂、ポリカーボネート樹脂、ポリフェニレンサルファイド樹脂、ポリスチレンなどが挙げられる。なかでも、含浸性、コスト、物性の点から、ポリオレフィン系樹脂、ポリアミド系樹脂、ポリエステル系樹脂が本発明において好適である。ポリオレフィン系樹脂としては、例えば、ポリプロピレン、ポリエチレンなど；ポリアミド系樹脂としては、例えば、ナイロン６，６、ナイロン６、ナイロン１２、ＭＸＤナイロンなど；ポリエステル系樹脂としては、例えば、ポリエチレンテレフタレート、ポリブチレンテレフタレートなどが挙げられ、これらの樹脂を用いることが、本発明においては特に好ましい。これらの樹脂には着色剤、変性剤、酸化防止剤および耐紫外線剤などの添加剤や、炭酸カルシウム、タルク、マイカなどのフィラーを混合して用いても差し支えない。
【０００９】
また、本発明においてＬＦＲＴＰ基材に用いる繊維としては、例えば、ガラス繊維、炭素繊維、アラミド繊維、セラミック繊維などが挙げられ、これらを単独あるいは混合して使用することができる。中でもガラス繊維を用いることが、コストパフォーマンスに優れるので好ましい。
【００１０】
上記繊維は、そのモノフィラメントの平均径が通常は６〜２３μｍであり、さらに１０〜１７μｍであることが好ましい。モノフィラメントの平均径が６μｍ未満の場合は成形体がコスト高になるとともに、ＬＦＲＴＰ基材において繊維の含有率が同じ場合には、繊維の表面積が大きくなり、成形時の流動性が劣るので好ましくない。一方、モノフィラメントの平均径が２３μｍを超える場合は、最終的に得られるＬＦＲＴＰ成形体の機械的物性が劣るために好ましくない。
【００１１】
また、切断前の連続繊維は、フィラメント数が１００〜１２０００本が好ましい。フィラメント数が１００本未満であると、後工程において多数本のＬＦＲＴＰ基材が必要となり、作業が煩雑となる。一方、フィラメント数が１２０００本を超えると、モノフィラメント間にまで熱可塑性樹脂を均一に含浸させることが困難になるとともに、得られるＬＦＲＴＰ基材が太くなり、後述するＬＦＲＴＰ基材径が得られにくくなる。さらに、ＬＦＲＴＰ成形体にした場合、繊維の分散性に劣り、最終的に得られるＬＦＲＴＰ成形体において期待する強度を発現することができない。また、後述するＬＦＲＴＰ基材の平均径または平均厚さが０．０５〜１．５ｍｍのように細い場合には、繊維の含有量を考慮してフィラメント数が１００〜６０００本であることが好ましい。
【００１２】
また、本発明に用いるＬＦＲＴＰ基材は、その径または厚さが０．０５〜２．５ｍｍであることを必須とする。ＬＦＲＴＰ基材の径または厚さが０．０５ｍｍ未満であると、ＬＦＲＴＰ基材を作製する際に、フィラメント切れや羽毛立ちが生じ、生産性が劣る。また、２．５ｍｍを超えると、加熱搬送時の加熱効率が劣り、さらに、得られるＬＦＲＴＰ基材が太く、または厚くなって繊維の分散性が劣るために、最終的に得られるＬＦＲＴＰ成形体において期待する機械的強度を発現することができず好ましくない。さらに０．０５〜１．５ｍｍであることが好ましい。前記範囲において径または厚みの小さいＬＦＲＴＰ基材を用いると、成形の際に繊維の分散が良好となり、均一で高い強度の成形体を得ることが可能となる。さらに、ＬＦＲＴＰ基材の径または厚みを前記範囲において小さくすることで加熱効率を高くし、ＬＦＲＴＰ基材を容易に溶融することが可能となり、搬送する際に繊維の破損が低減される。
【００１３】
また、本発明に用いるＬＦＲＴＰ基材は、繊維の含有率が通常は１５〜８０容量％であり、さらに２０〜７０容量％であることが好ましい。繊維の含有率が１５容量％未満の場合は、繊維による成形体の補強効果が低く、一方、繊維の含有率が８０容量％を超える場合は、繊維を包むマトリックス（熱可塑性樹脂）の相対量が少なすぎ、後述する樹脂の含浸率を９５％以上に確保することが困難となる。
【００１４】
本発明に用いるＬＦＲＴＰ基材は、前記熱可塑性樹脂の含浸率が９５％以上であることが好ましい。得られるＬＦＲＴＰ成形体において前記熱可塑性樹脂の含浸率が９５％未満であると、ＬＦＲＴＰ基材の作成の際に毛羽の発生や可塑化時のフィラメントの破断が促進されたり、得られた成形体の表面に繊維が浮き出したりするため、あまり好ましくない。ここで樹脂の含浸率とは、ＬＦＲＴＰ基材の断面を２００倍の電子顕微鏡で観察し、２０μｍのメッシュをおいて、メッシュのセル中に少しでもボイド（空気の泡）が認められれば、このメッシュのセルをボイド面積として加え、観察した全断面積とボイド面積とから以下の数式によって求めたものである。
｛（全断面積−ボイド面積）／全断面積｝×１００（％）
【００１５】
本発明に用いるＬＦＲＴＰ基材の長さは、１０〜５０ｍｍであることを必須とし、１５〜４０ｍｍであることが好ましい。本発明のＬＦＲＴＰ基材は連続繊維に熱可塑性樹脂を含浸させて切断したものであるため、ＬＦＲＴＰ基材の長さは該基材中の繊維の長さとほぼ等しいものである。従って、切断長が１０ｍｍ未満の場合には、加熱溶融して得られた溶融物中の繊維の平均長を加熱溶融前のＬＦＲＴＰ基材長の４０％以上保持させたとしても、最終的に得られるＬＦＲＴＰ成形体の機械的物性が劣るために好ましくない。一方、切断長が５０ｍｍを超える場合は、加熱搬送機に導入する際の取扱い性が劣り、また、ＬＦＲＴＰ基材のプレス成形時の流動性が劣るために好ましくない。
【００１６】
ＬＦＲＴＰ基材を作製する方法は、繊維ストランドを樹脂含浸槽に送り込み、溶融含浸法により樹脂を繊維ストランド中に含浸させた後、１本または複数本の繊維ストランドを１個のノズルにより引き抜いてＬＦＲＴＰ基材を得る方法が好ましい。さらに、スプリットを施すことなく集束した１本の繊維ストランドを１個のノズルから引き抜く方法を採用すると、ノズルからの引き抜きが容易となり、繊維の含有率を高めることができ、かつ、毛羽の発生を少なくすることができるために好ましい。
【００１７】
この方法では、より径の小さいＬＦＲＴＰ基材が得られ易い。この得られたＬＦＲＴＰ基材は熱容量が小さく、容易に軟化または固化させることができて、加熱する時間を短縮させることが可能となるため、加熱時の樹脂の熱劣化を最小限に留めることが可能であり、溶融物の残存繊維長を長くすることが可能となる。
【００１８】
本発明のＬＦＲＴＰ成形体の製造方法は、前述したＬＦＲＴＰ基材または該基材と非強化樹脂との混合物（以下該混合物も単に「ＬＦＲＴＰ基材」という）を用いるか、または該ＬＦＲＴＰ基材を集合させた塊状物を、加熱搬送した溶融物中の繊維の平均長を元のＬＦＲＴＰ基材長の４０％以上、好ましくは６０％以上、さらに好ましくは８０％以上に保持するように、加熱溶融しながら搬送して溶融物を作製し、該溶融物を成形型に供給してプレス成形する方法である。上記混合物に用いる非強化樹脂とは、前述した繊維を実質的に含まない熱可塑性樹脂であり、使用する場合の非強化樹脂は、ＬＦＲＴＰ基材を構成している熱可塑性樹脂と同種の樹脂を用いることが好ましい。また、その使用量は、混合物中の繊維の量が混合物中で１５容量％以上を保持できる量であることが好ましい。
【００１９】
本発明で、ＬＦＲＴＰ基材を成形型に供給するためには、加熱搬送する工程が必要となる。加熱工程では、用いる熱可塑性樹脂の軟化点温度以上で加熱することで、ＬＦＲＴＰ基材に柔軟性を与え、搬送の際に繊維の破損を防止すると共にＬＦＲＴＰ基材同士を容易に融着させることができる。また、搬送工程ではＬＦＲＴＰ基材にできるだけ剪断を加えずに成形型に供給することで、繊維の破損を防止する。
【００２０】
前述の溶融物中の繊維の平均長は、前記溶融物を６００℃で焼失させた後、繊維１００本を任意に選んで万能投影機で繊維長を測定し、それらの平均値を求めることにより測定することができる。
【００２１】
前記溶融物中の繊維の平均長が、元のＬＦＲＴＰ基材長の４０％以上を保持しながら、ＬＦＲＴＰ基材を加熱搬送する方法は、スクリュー押出機、プランジャー押出機、ベルトコンベヤーによる搬送方法などが挙げられるが、特に下記の方法が好ましく採用される。
（ａ）ＬＦＲＴＰ基材の長さ以上の径のシリンダーを有し、先端の押出口の絞り率が１．０〜１００で、好ましくは１．０〜２０であり、かつ押出口の径がＬＦＲＴＰ基材の長さ以上の径を有し押出口にシャッター機能を備えたプランジャー押出機を有する加熱搬送機を用いる方法であり、押出口の絞り率が１００を超える場合は、繊維の破断を増大させる。
【００２２】
（ｂ）加熱搬送機がＬＦＲＴＰ基材の長さ以上のシリンダー径を有し、押出口にシャッター機能を備えたインラインスクリュー式射出機能を備えたものであり、可塑化部のスクリューの圧縮比が１．１〜１．８であり、先端の押出口の絞り率が１．０〜１００で、好ましくは１．０〜２０であり、かつ押出口の径がＬＦＲＴＰ基材の長さ以上の径を有し、逆流防止リングを備えていないものを用いる方法であり、この場合、圧縮比が１．１未満であると搬送能力が劣り、１．８を超える場合は剪断力が大きくなり、繊維の破断を増大させる。押出口の絞り率が１００を超える場合は、繊維の破断を増大させる。
【００２３】
（ｃ）加熱搬送機がＬＦＲＴＰ基材の長さ以上のシリンダー径を有し、押出口にシャッター機能を備えたスクリュープリプラ式射出機能を備えたものであり、可塑化部のスクリューの圧縮比が１．１〜１．８であり、先端の押出口の絞り率が１．０〜１００で、好ましくは１．０〜２０であり、かつ押出口の径がＬＦＲＴＰ基材の長さ以上の径を有するものを用いる方法であり、この場合、圧縮比が１．１未満であると搬送能力が劣り、１．８を超える場合は剪断力が大きくなり、繊維の破断を増大させる。押出口の絞り率が１００を超える場合は、繊維の破断を増大させる。
なお、ここでいう押出口の絞り率とは、押出口を備えたシリンダー断面積／押出口断面積で表され、シリンダー断面積は前記（ｃ）の搬送機の場合、プランジャー部（計量部）のシリンダー断面積を指す。
【００２４】
ＬＦＲＴＰ基材の搬送にプランジャー押出機を用いる方法（ａ）の場合には、定量的にＬＦＲＴＰ基材をシリンダーに投入し、加熱しながらＬＦＲＴＰ基材を切断しないようにゆっくり押圧する。また、可塑化するにあたってはシリンダー内に熱風を吹き込むことにより効率的に可塑化することが可能となる。さらに溶融した塊状物を定量的に押出機から押出すことが可能である。
【００２５】
ＬＦＲＴＰ基材の加熱搬送に際し、（ｂ）および（ｃ）用いる場合のスクリューは、一軸または二軸であることが好ましい。スクリューの形態としては特に限定はないが、スクリューのピッチおよび／またはスクリューの溝深さがＬＦＲＴＰ基材の長さ以上であることが好ましい。ここでいう圧縮比とは、スクリューの溝の深さをｈｆで表し、スクリューの先端の溝の深さをｈｍで表したときのｈｆ／ｈｍの値である。
【００２６】
また、本発明では、前記スクリューによる可塑化と、プランジャーによる計量押出とを併用するスクリュープリプラ射出機能を備えた方法（ｃ）の場合、ＬＦＲＴＰ基材を加熱しながらスクリューで搬送することで、ＬＦＲＴＰ基材の樹脂を十分に溶融させてＬＦＲＴＰ基材同士を融着させ、プランジャーにより纏まった溶融塊を計量して成形型へ供給することが可能となる。
【００２７】
また、本発明では、必要によりＬＦＲＴＰ基材の搬送にベルトコンベヤーを用いることが可能である。この場合、周りに加熱器や熱風発生機を備えたベルトコンベヤーを用いることが好ましく、さらに、不活性ガス雰囲気下であることがより好ましい。ベルトの素材は四フッ化エチレン樹脂などのフッ素系樹脂やＳＵＳメッシュなどを用いることが好ましい。また、ベルトコンベアーとプランジャー押出を併用することも可能である。
【００２８】
上記のように加熱搬送されたＬＦＲＴＰ基材の溶融物は、加熱搬送機で計量するか、または加熱搬送機を経た後に計量し、計量後に直接成形型に供給するか、計量後に溶融物を、例えば、ロボット、人手などで移動させて成形型に供給する。これらの供給方法は、用いる熱可塑性樹脂の流動性、表面外観性、固化時間を考慮して適宜選択することができるが、成形流動性を向上させるために加熱搬送機で溶融物を計量し、溶融物を直接成形型に供給する方法が好ましい。
【００２９】
そして成形型に供給された溶融物をプレス成形することにより型内で流動し、成形型に接触され固化され成形体となる。成形型の温度は、熱可塑性樹脂の融点温度以下とし、さらに用いる熱可塑性樹脂の流動性、表面外観性、固化時間を考慮して適宜選択する。本発明により得られた成形体は表面が平滑で、樹脂の熱劣化を多く受けていないため、表面外観や機械的強度が極めて良好となる。
【００３０】
【実施例】
次に実施例および比較例を挙げて本発明をさらに具体的に説明する。
実施例１
平均径１３μｍのモノフィラメントを用いて、フィラメント数（集束本数）６００本のガラス繊維ストランド１本を、ＭＩ＝４０の酸変性した溶融ポリプロピレン（２６０℃）中に導入し、溶融含浸を行った後、内径０．５３ｍｍのダイのノズルから５０ｍ／ｍｉｎの速度で引き抜き、さらにペレタイザーで長さが２０ｍｍとなるように切断してＬＦＲＴＰ基材を得た。得られたＬＦＲＴＰ基材の平均径は０．５３ｍｍ、ガラス含有率は４５．５容量％、樹脂の含浸率はｎ＝５の平均値で１００％であった。なお、上記においてｎは測定数を表わす。
【００３１】
また、ＬＦＲＴＰ基材長は、任意に選んだ１０本の平均をとり２０ｍｍの測定値を得た。ガラス含有率の測定は、まず、得られたＬＦＲＴＰ基材を６００℃の電気炉中で加熱して樹脂を焼失させた後、残ったガラスの重量を測定して、ガラス含有率７０重量％の測定値を得た。この値から樹脂の比重を０．９１、ガラス繊維の比重を２．５４として容量％に換算した。
【００３２】
ついで得られたＬＦＲＴＰ基材を、内径９０ｍｍ、押出口内径９０ｍｍ、押出口絞り率１．０で押出口先端にシャッター機構を備え、２３０℃に加熱されているシリンダー内に投入し可塑化溶融を行った。溶融物をプランジャーで押すことにより溶融塊を作製し、シャッターを開放させ、さらにプランジャーを押すことにより溶融塊を取り出した。なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して、１９ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の９５％であった。
【００３３】
つぎに溶融物を、図１に図解的に示すように、上型と下型との間に縦２００ｍｍ、横２００ｍｍ、高さ５０ｍｍおよび厚さ３ｍｍの箱型のキャビティを成形し得るプレス成形型に移行させた。油圧プレスを用いて１５０ｋｇ／ｃｍ^２の圧力で１分間プレスした。この成形体において溶融物を成形型に移した際、最初に接地した部分（チャージ部）からＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００３４】
実施例２
ダイのノズル径を１．０ｍｍに変えた以外は実施例１と同様にしてＬＦＲＴＰ基材を得た。得られたＬＦＲＴＰ基材の平均径は１．０ｍｍ、ガラス含有率は１９．３容量％、樹脂の含浸率はｎ＝５の平均値で９８％であった。得られたＬＦＲＴＰ基材を、実施例１と同様に溶融塊を作製した。なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して、１９ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の９５％であった。以下実施例１と同様に成形体を得、ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００３５】
実施例３
実施例１で得られたＬＦＲＴＰ基材と非強化のポリプロピレン樹脂（ＭＩ＝４０）をドライブレンドし、全体としてのガラス含有率が１９．３容量％となるように混合した。この混合物を、押出口先端にシャッター機構を備えたスクリュープリプラ式（可塑化部シリンダー径：９０ｍｍ、圧縮比１．４、プランジャー部（計量部）シリンダー径１５０ｍｍ、押出口径１００ｍｍ）の射出機能を備えた加熱搬送機で可塑化を行い、溶融塊を作製した。
【００３６】
なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して、９ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の４５％であった。以下実施例１と同様に成形体を得、ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００３７】
実施例４
平均径１３μｍのモノフィラメントを用いて、フィラメント数（集束本数）を６００本のガラス繊維ストランドを１６本束ねて、ＭＩ＝４０の酸変性した溶融ポリプロピレン（２６０℃）中に導入し、溶融含浸を行った後、内径２．２ｍｍのダイのノズルから３０ｍ／ｍｉｎの速度で引き抜き、さらにペレタイザーで長さが２０ｍｍとなるように切断してＬＦＲＴＰ基材を得た。得られたＬＦＲＴＰ基材の平均径は２．２ｍｍ、ガラス含有率は４５．５容量％、樹脂の含浸率はｎ＝５の平均値で９８％であった。なお、上記においてｎは測定数を表わす。得られたＬＦＲＴＰ基材と非強化のポリプロピレン樹脂（ＭＩ＝４０）をドライブレンドし、ガラス含有率が１９．３容量％となるように混合した。
【００３８】
この混合物を、先端にシャッター機構を備え逆流防止リングのないインラインスクリュー式（シリンダー径９０ｍｍ、圧縮比１．４、押出口径９０ｍｍ）の射出機能を備えた加熱搬送機で可塑化を行い、溶融塊を作製した。なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して、８．２ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の４１％であった。以下実施例１と同様に成形体を得、ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００３９】
比較例１
平均径１３μｍのモノフィラメントを用いて、フィラメント数（集束本数）を６００本のガラス繊維ストランドを３０本束ねて、ＭＩ＝４０の酸変性した溶融ポリプロピレン（２６０℃）中に導入し、溶融含浸を行った後、内径３．０ｍｍのダイのノズルから１５ｍ／ｍｉｎの速度で引き抜き、さらにペレタイザーで長さが２０ｍｍとなるように切断してＬＦＲＴＰ基材を得た。得られたＬＦＲＴＰ基材の平均径は３．０ｍｍ、ガラス含有率は４５．５容量％、樹脂の含浸率はｎ＝５の平均値で９４％であった。なお、上記においてｎは測定数を表わす。
【００４０】
ついで得られたＬＦＲＴＰ基材を、押出口先端にシャッター機構を備え２３０℃に加熱されている内径９０ｍｍのシリンダー内に投入し可塑化を行った。溶融物をプランジャーで押すことにより溶融塊を作製し、シャッターを開放させ、さらにプランジャーを押すことにより溶融塊を取り出した。
【００４１】
なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して、１９ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の９５％であった。以下実施例１と同様に成形体を得、ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００４２】
比較例２
比較例１で得られたＬＦＲＴＰ基材と非強化のポリプロピレン樹脂（ＭＩ＝４０）をドライブレンドし、ガラス含有率が１９．３容量％となるように混合した。
【００４３】
この混合物を、実施例４と同様なインラインスクリュー式の射出機能を備えた加熱搬送機で可塑化を行い、溶融塊を作製した。なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して、７．０ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の３５％であった。以下実施例１と同様に成形体を得、ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００４４】
比較例３
比較例１で得られたＬＦＲＴＰ基材と非強化のポリプロピレン樹脂（ＭＩ＝４０）をドライブレンドし、ガラス含有率が１９．３容量％となるように混合した。この混合物を、実施例３と同様なスクリュープリプラ式の射出機能を備えた加熱搬送機で可塑化を行い、溶融塊を作製した。なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して、６．８ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の３４％であった。以下実施例１と同様に成形体を得、ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００４５】
比較例４
比較例１で得られたＬＦＲＴＰ基材と非強化のポリプロピレン樹脂（ＭＩ＝４０）をドライブレンドし、ガラス含有率が１９．３容量％となるように混合した。この混合物を、逆流防止リングを備えたインライン式（シリンダー径９０ｍｍ、圧縮比２．４、押出口径５．０ｍｍ）の射出機能を備えた加熱搬送機を用いて可塑化を行い、溶融塊を作成した。なお、溶融物中の繊維の平均長の測定は、溶融物を６００℃で焼失させた後、残ったガラス繊維のモノフィラメントを任意に１００本選び、その平均値を測定して２．８ｍｍの測定値を得た。繊維の平均長は元のＬＦＲＴＰ基材長の１４％であった。以下実施例１と同様に成形体を得、ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。
【００４６】
比較例５
実施例１と同様のＬＦＲＴＰ基材を均一分散して、一旦、平板プレスで５ｋｇ／ｃｍ²の圧力で押圧することにより、３．８ｍｍ厚のシートを作成した後、縦１７６ｍｍ、横１７６ｍｍに切り出したシート状の予備成形体を作成し、このシートを十分加熱し、実施例で用いたと同じプレス成形型に２枚重ねて移送し、１５０ｋｇ／ｃｍ²の圧力で１分間プレスしてＬＦＲＴＰ成形体を得た。ＡＳＴＭＤ２５６およびＤ７９０に準拠した形で試験片を切り出し、各ｎ＝３で、曲げ強度、曲げ弾性率およびシャルピー（フラットワイズ）衝撃強度の測定を行った。その平均値を表１に示す。この方法では上記のようにシート化工程を経るために生産効率が劣るものであった。
【００４７】

【００４８】

【００４９】
【発明の効果】
本発明によれば、あまり剪断を加えずにＬＦＲＴＰ基材を加熱搬送することにより、成形体中の繊維を長く保持することが可能となり、成形体の機械的強度、特に衝撃強度を向上させると共に、繊維のモノフィラメント化を低減させて成形時の溶融物の流動性を良好にすることができる。
さらに、本発明では加熱工程を伴うシート化を経ることなく成形するため、樹脂の熱劣化を抑えると共に、柔らかくなった溶融シートを複数枚成形型に移動させるという従来技術の煩雑な作業を不要にするものである。
【図面の簡単な説明】
【図１】本発明の方法を図解的に説明する図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a molded article of a long fiber reinforced thermoplastic resin (hereinafter referred to as “LFRTP”) suitable for automobile parts, home appliances, industrial materials, civil engineering materials and the like that require surface appearance, high strength, and high rigidity. About.
[0002]
[Prior art]
Conventionally, in an LFRTP molded body manufacturing method, an LFRTP base material having a diameter of about 2 to 3 mm, which is obtained by cutting a thermoplastic resin containing reinforcing fibers arranged in a specific direction (hereinafter simply referred to as “fiber”) into a predetermined shape, is heated. A method is known in which a molded body is produced by melting and injection molding. The LFRTP base material used in this method has a longer fiber length than the conventional short fiber reinforced thermoplastic resin base material in which thermoplastic resin and fibers are kneaded, and maintains the fiber length in the molded body longer. In addition, since the fiber was impregnated with the thermoplastic resin in advance, the molded body obtained by molding the fiber was excellent in mechanical strength and surface appearance.
[0003]
[Problems to be solved by the invention]
However, even when the LFRTP base material having a long fiber length used in the above method is used, a large shear is applied due to kneading with a screw having a high compression ratio and a high pressure at the time of injection, and the fiber length in the molded body is shortened. There was a problem that the mechanical strength such as impact strength and tensile strength of the molded product was inferior.
[0004]
Furthermore, an LFRTP base material sheet in which the LFRTP base material is dispersed and heat-molded, and a molded body obtained by heating and melting the sheet and introducing the sheet into a mold and heating or pressing at room temperature are known (special features). (Kaihei 9-109310). In this method, once a pre-formed LFRTP base sheet is prepared, it is a simple method in which the sheet is heated and melted and then set in a molding die and molded. Can be obtained for a relatively long time and a relatively high strength molded product can be obtained. In order to obtain the desired molded product, the LFRTP substrate production process, the sheet forming process and the press molding process It has been necessary to melt and soften the thermoplastic resin three times, which has problems in terms of energy efficiency and thermal degradation of the resin. Furthermore, when the LFRTP base sheet is sufficiently heated and melted to improve the fluidity at the time of molding, the sheet is so soft that the handling property is inferior. Doing so has the problem of complicating work.
Accordingly, an object of the present invention is to solve the above conventional problems and improve the mechanical strength of the obtained LFRTP molded body.
[0005]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, the present invention provides an LFRTP molded body in which an LFRTP base material is used alone or the base material is diluted with an unreinforced resin and melted to prepare a melt, and the melt is supplied to a mold and press-molded. In the method, the LFRTP base material is impregnated with a thermoplastic resin in one or more continuous fiber strands and pulled out from a nozzle.lengthCut to 10-50mmDiameter or thicknessAn LFRTP base material having a fiber content of 15 to 80% by volume of 0.05 to 2.5 mm, and the average length of the fibers in the melt is 40% of the original LFRTP base material length by heating and conveying the base material. Provided is a method for producing an LFRTP molded article, which comprises producing and molding a melt having the above length.
[0006]
In the present invention, when the LFRTP substrate is heated and conveyed, a molded product is produced by preparing a melt in which the average length of fibers in the melt is 40% or more of the original LFRTP substrate length. It is possible to improve the mechanical strength of the molded body by keeping the average length of the fibers therein long.
[0007]
In addition, in the present invention, since the sheet is formed without a heating step, the heat deterioration of the resin is suppressed, and the complicated work of the conventional technique of moving the softened molten sheet to a plurality of molds is unnecessary. To do.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to preferred embodiments.
The thermoplastic resin used in the present invention is not particularly limited, and various commercially available resins can be used. For example, polyolefin resin, polyamide resin, polyester resin, polycarbonate resin, polyphenylene sulfide resin, polystyrene and the like can be mentioned. Of these, polyolefin resins, polyamide resins, and polyester resins are suitable in the present invention in terms of impregnation properties, cost, and physical properties. Examples of polyolefin resins include polypropylene and polyethylene; examples of polyamide resins include nylon 6,6, nylon 6, nylon 12, and MXD nylon; examples of polyester resins include polyethylene terephthalate and polybutylene terephthalate. It is particularly preferable in the present invention to use these resins. These resins may be used in admixture with additives such as colorants, modifiers, antioxidants and UV-resistant agents, and fillers such as calcium carbonate, talc and mica.
[0009]
Moreover, as a fiber used for a LFRTP base material in this invention, glass fiber, carbon fiber, an aramid fiber, a ceramic fiber etc. are mentioned, for example, These can be used individually or in mixture. Among these, it is preferable to use glass fiber because it is excellent in cost performance.
[0010]
The fiber has an average monofilament diameter of usually 6 to 23 μm, more preferably 10 to 17 μm. When the average diameter of the monofilament is less than 6 μm, the molded body is expensive, and when the fiber content is the same in the LFRTP base material, the surface area of the fiber becomes large and the fluidity during molding is not preferable. . On the other hand, when the average diameter of the monofilament exceeds 23 μm, it is not preferable because the mechanical properties of the finally obtained LFRTP molded product are inferior.
[0011]
Moreover, as for the continuous fiber before a cutting | disconnection, 100-12000 filament number is preferable. If the number of filaments is less than 100, a large number of LFRTP base materials are required in the subsequent process, and the operation becomes complicated. On the other hand, when the number of filaments exceeds 12,000, it becomes difficult to uniformly impregnate the thermoplastic resin between the monofilaments, and the obtained LFRTP substrate becomes thick, making it difficult to obtain the LFRTP substrate diameter described later. . Furthermore, when the LFRTP molded body is used, the dispersibility of the fibers is inferior, and the expected strength cannot be expressed in the finally obtained LFRTP molded body. Moreover, when the average diameter or average thickness of the LFRTP base material described later is as thin as 0.05 to 1.5 mm, the number of filaments is preferably 100 to 6000 in consideration of the fiber content. .
[0012]
The LFRTP base material used in the present invention isDiameter or thicknessIs required to be 0.05 to 2.5 mm. LFRTP base materialDiameter or thicknessWhen the thickness is less than 0.05 mm, when the LFRTP substrate is produced, filament breakage and feathering occur, resulting in poor productivity. Further, if it exceeds 2.5 mm, the heating efficiency at the time of heating and conveyance is inferior, and furthermore, since the obtained LFRTP base material is thick or thick and the dispersibility of the fibers is inferior, in the finally obtained LFRTP molded product It is not preferable because the expected mechanical strength cannot be expressed. Furthermore, it is preferable that it is 0.05-1.5 mm. When an LFRTP base material having a small diameter or thickness in the above range is used, the dispersion of fibers becomes good at the time of molding, and a molded body having a uniform and high strength can be obtained. Furthermore, by reducing the diameter or thickness of the LFRTP substrate within the above range, the heating efficiency can be increased, and the LFRTP substrate can be easily melted, and fiber breakage is reduced during transportation.
[0013]
The LFRTP base material used in the present invention has a fiber content of usually 15 to 80% by volume, more preferably 20 to 70% by volume. When the fiber content is less than 15% by volume, the effect of reinforcing the molded body by the fiber is low. On the other hand, when the fiber content exceeds 80% by volume, the relative amount of the matrix (thermoplastic resin) that wraps the fiber. Is too small, and it becomes difficult to ensure that the resin impregnation rate described below is 95% or more..
[0014]
The LFRTP base material used in the present invention preferably has an impregnation ratio of the thermoplastic resin of 95% or more. In the obtained LFRTP molded article, if the impregnation ratio of the thermoplastic resin is less than 95%, generation of fuzz at the time of producing the LFRTP base material or breakage of the filament during plasticization is promoted, or the obtained molded article This is not preferable because the fibers are raised on the surface of the film. Here, the resin impregnation rate means that the cross section of the LFRTP substrate is observed with an electron microscope of 200 times, a 20 μm mesh is placed, and if any void (air bubbles) is observed in the mesh cell, The mesh cell is added as a void area, and is calculated from the observed total cross-sectional area and void area by the following formula.
{(Total cross-sectional area−void area) / total cross-sectional area} × 100 (%)
[0015]
The length of the LFRTP base material used in the present invention is required to be 10 to 50 mm, and preferably 15 to 40 mm. Since the LFRTP base material of the present invention is obtained by impregnating a continuous fiber with a thermoplastic resin and cut, the length of the LFRTP base material is substantially equal to the length of the fiber in the base material. Therefore, when the cutting length is less than 10 mm, even if the average length of the fibers in the melt obtained by heating and melting is maintained at 40% or more of the LFRTP base material length before heating and melting, it is finally obtained. This is not preferable because the mechanical properties of the LFRTP molded product obtained are inferior. On the other hand, when the cutting length exceeds 50 mm, the handling property when introduced into a heating / conveying machine is inferior, and the fluidity during press molding of the LFRTP base material is inferior.
[0016]
The method for producing the LFRTP substrate is to send fiber strands into a resin impregnation tank, impregnate the resin into the fiber strands by a melt impregnation method, and then pull out one or more fiber strands with a single nozzle. A method for obtaining a substrate is preferred. Furthermore, if a method of pulling one bundle of fiber strands without splitting from one nozzle is adopted, it is easy to pull out from the nozzle, the fiber content can be increased, and the generation of fluff is prevented. This is preferable because it can be reduced.
[0017]
In this method, an LFRTP base material having a smaller diameter is easily obtained. Since the obtained LFRTP base material has a small heat capacity, it can be easily softened or solidified, and the heating time can be shortened, so that thermal degradation of the resin during heating can be kept to a minimum. It is possible to lengthen the remaining fiber length of the melt.
[0018]
The method for producing an LFRTP molded body of the present invention uses the aforementioned LFRTP base material or a mixture of the base material and a non-reinforced resin (hereinafter, the mixture is also simply referred to as “LFRTP base material”), or uses the LFRTP base material. Heat and melt the aggregated mass so that the average length of the fibers in the melt conveyed by heating is maintained at 40% or more, preferably 60% or more, more preferably 80% or more of the original LFRTP substrate length. In this method, a melt is produced by conveying the melt while being fed, and the melt is supplied to a mold and press-molded. The non-reinforced resin used in the above mixture is a thermoplastic resin that does not substantially contain the above-described fibers. When used, the non-reinforced resin is the same type of resin as the thermoplastic resin that constitutes the LFRTP base material. It is preferable to use it. Moreover, it is preferable that the usage-amount is the quantity which the quantity of the fiber in a mixture can hold | maintain 15 volume% or more in a mixture.
[0019]
In the present invention, in order to supply the LFRTP base material to the mold, a heating and conveying step is required. In the heating step, the LFRTP base material is given flexibility by heating at a temperature equal to or higher than the softening point temperature of the thermoplastic resin used, and the LFRTP base materials are easily fused together while preventing fiber breakage during transportation. Can do. Moreover, in a conveyance process, damage to a fiber is prevented by supplying to a shaping | molding die, applying as little shear as possible to a LFRTP base material.
[0020]
in frontAverage length of fibers in the melt described aboveIsAfter the melt was burned off at 600 ° C., 100 fibers were arbitrarily selected and the fiber length was measured with a universal projector.It can be measured by determining the average value.
[0021]
The method of heating and conveying the LFRTP substrate while maintaining the average length of the fibers in the melt at 40% or more of the original LFRTP substrate length is a conveyance method using a screw extruder, a plunger extruder, or a belt conveyor. The following methods are particularly preferably employed.
(A) It has a cylinder with a diameter equal to or longer than the length of the LFRTP base material, the drawing rate of the extrusion port at the tip is 1.0 to 100, preferably 1.0 to 20, and the diameter of the extrusion port is LFRTP. It is a method using a heating and conveying machine having a plunger extruder having a diameter greater than the length of the substrate and having a shutter function at the extrusion port. When the squeezing rate of the extrusion port exceeds 100, the fiber breaks. Increase.
[0022]
(B) The heating / conveying machine has a cylinder diameter equal to or longer than the length of the LFRTP base material, and has an inline screw type injection function with a shutter function at the extrusion port. 1.1 to 1.8, the squeezing rate of the extrusion port at the tip is 1.0 to 100, preferably 1.0 to 20, and the diameter of the extrusion port is equal to or larger than the length of the LFRTP substrate. In this case, when the compression ratio is less than 1.1, the conveying ability is inferior, and when it exceeds 1.8, the shearing force increases, and the fiber Increase the breakage of When the squeezing rate of the extrusion port exceeds 100, the fiber breakage is increased.
[0023]
(C) The heating / conveying machine has a cylinder diameter equal to or longer than the length of the LFRTP base material, and has a screw pre-plastic injection function with a shutter function at the extrusion port, and the compression ratio of the screw of the plasticizing part is 1.1 to 1.8, the squeezing rate of the extrusion port at the tip is 1.0 to 100, preferably 1.0 to 20, and the diameter of the extrusion port is equal to or larger than the length of the LFRTP substrate. In this case, if the compression ratio is less than 1.1, the conveying ability is inferior, and if it exceeds 1.8, the shearing force increases and the fiber breakage increases. When the squeezing rate of the extrusion port exceeds 100, the fiber breakage is increased.
Here, the squeezing rate of the extrusion port is represented by the cross-sectional area of the cylinder provided with the extrusion port / the cross-sectional area of the extrusion port. ) Refers to the cross-sectional area of the cylinder.
[0024]
In the case of the method (a) in which the plunger extruder is used for transporting the LFRTP base material, the LFRTP base material is quantitatively charged into the cylinder and slowly pressed so as not to cut the LFRTP base material while heating. Further, when plasticizing, it is possible to efficiently plasticize by blowing hot air into the cylinder. Further, the molten mass can be quantitatively extruded from the extruder.
[0025]
When the LFRTP base material is heated and conveyed, the screws used in (b) and (c) are preferably uniaxial or biaxial. Although there is no limitation in particular as a form of a screw, it is preferable that the pitch of a screw and / or the groove depth of a screw are more than the length of a LFRTP base material. The compression ratio here is a value of hf / hm when the depth of the groove of the screw is represented by hf and the depth of the groove at the tip of the screw is represented by hm.
[0026]
Further, in the present invention, in the case of the method (c) having a screw pre-plastic injection function that uses both the plasticization by the screw and the metering extrusion by the plunger, the LFRTP substrate is conveyed by the screw while being heated, The resin of the LFRTP base material is sufficiently melted so that the LFRTP base materials are fused together, and the molten mass collected by the plunger can be measured and supplied to the mold.
[0027]
Moreover, in this invention, it is possible to use a belt conveyor for conveyance of a LFRTP base material as needed. In this case, it is preferable to use a belt conveyor provided with a heater and a hot air generator around it, and more preferably in an inert gas atmosphere. The material of the belt is preferably a fluorine resin such as tetrafluoroethylene resin or SUS mesh. Moreover, it is also possible to use a belt conveyor and plunger extrusion together.
[0028]
The melt of the LFRTP base material heated and transported as described above is weighed by a heat transport machine or weighed after passing through a heat transport machine, and directly supplied to the mold after the measurement, or the melt after the measurement, For example, it is moved by a robot or a human hand and supplied to the mold. These supply methods can be appropriately selected in consideration of the fluidity, surface appearance, and solidification time of the thermoplastic resin to be used, but in order to improve the molding fluidity, the melt is measured with a heating and conveying machine, A method of supplying the melt directly to the mold is preferred.
[0029]
Then, the melt supplied to the mold is press-molded to flow in the mold, and is contacted with the mold and solidified to form a molded body. The temperature of the molding die is set to be equal to or lower than the melting point temperature of the thermoplastic resin, and is appropriately selected in consideration of the fluidity, surface appearance, and solidification time of the thermoplastic resin used. Since the molded body obtained by the present invention has a smooth surface and does not receive much heat deterioration of the resin, the surface appearance and mechanical strength are extremely good.
[0030]
【Example】
Next, the present invention will be described more specifically with reference to examples and comparative examples.
Example 1
Using monofilaments with an average diameter of 13 μm, one glass fiber strand with 600 filaments (number of bundles) was introduced into acid-modified molten polypropylene (260 ° C.) with MI = 40, and after melt impregnation, The LFRTP base material was obtained by pulling out from a die nozzle with an inner diameter of 0.53 mm at a speed of 50 m / min and further cutting with a pelletizer to a length of 20 mm. The obtained LFRTP base material had an average diameter of 0.53 mm, a glass content of 45.5% by volume, and an impregnation rate of the resin of 100% as an average value of n = 5. In the above, n represents the number of measurements.
[0031]
Moreover, the LFRTP base material length took the average of 10 arbitrarily selected, and obtained the measured value of 20 mm. The glass content was measured by first heating the obtained LFRTP substrate in an electric furnace at 600 ° C. to burn out the resin, then measuring the weight of the remaining glass, and measuring the glass content of 70% by weight. Measurements were obtained. From this value, the specific gravity of the resin was 0.91 and the specific gravity of the glass fiber was 2.54, which was converted to volume%.
[0032]
Next, the obtained LFRTP base material has an inner diameter of 90 mm, an extrusion port inner diameter of 90 mm, an extrusion port squeeze ratio of 1.0 and a shutter mechanism at the tip of the extrusion port. went. The molten mass was produced by pushing the melt with a plunger, the shutter was opened, and the molten mass was taken out by further pushing the plunger. In addition, the measurement of the average length of the fiber in a melt is a measurement value of 19 mm by measuring 100 monofilaments of the remaining glass fiber arbitrarily after burning off the melt at 600 ° C. and measuring the average value. Got. The average fiber length was 95% of the original LFRTP substrate length.
[0033]
Next, as schematically shown in FIG. 1, a press mold capable of forming a box-shaped cavity having a length of 200 mm, a width of 200 mm, a height of 50 mm, and a thickness of 3 mm between the upper mold and the lower mold. It was moved to. 150kg / cm using a hydraulic press²For 1 minute. When the melt was transferred to the mold in this molded body, a test piece was cut out from the first grounded part (charge part) in a form conforming to ASTM D256 and D790, and each n = 3, bending strength, flexural modulus. And Charpy (flatwise) impact strength was measured. The average value is shown in Table 1.
[0034]
Example 2
An LFRTP substrate was obtained in the same manner as in Example 1 except that the die nozzle diameter was changed to 1.0 mm. The obtained LFRTP base material had an average diameter of 1.0 mm, a glass content of 19.3% by volume, and a resin impregnation rate of 98% as an average value of n = 5. A molten lump was produced from the obtained LFRTP substrate in the same manner as in Example 1. In addition, the measurement of the average length of the fiber in a melt is a measurement value of 19 mm by measuring 100 monofilaments of the remaining glass fiber arbitrarily after burning off the melt at 600 ° C. and measuring the average value. Got. The average fiber length was 95% of the original LFRTP substrate length. Thereafter, a molded body is obtained in the same manner as in Example 1, and a test piece is cut out in a form conforming to ASTM D256 and D790, and bending strength, bending elastic modulus and Charpy (flatwise) impact strength are measured at each n = 3. It was. The average value is shown in Table 1.
[0035]
Example 3
The LFRTP base material obtained in Example 1 and an unreinforced polypropylene resin (MI = 40) were dry blended and mixed so that the total glass content was 19.3 vol%. The mixture has an injection function of a screw pre-plastic type (plasticizer cylinder diameter: 90 mm, compression ratio 1.4, plunger part (metering part) cylinder diameter 150 mm, extrusion port diameter 100 mm) equipped with a shutter mechanism at the tip of the extrusion port. Plasticization was performed with the equipped heating and conveying machine to produce a molten lump.
[0036]
In addition, the measurement of the average length of the fibers in the melt was performed by burning out the melt at 600 ° C., and then arbitrarily selecting 100 monofilaments of the remaining glass fibers, measuring the average value, and measuring 9 mm. Got. The average fiber length was 45% of the original LFRTP substrate length. Thereafter, a molded body is obtained in the same manner as in Example 1, and a test piece is cut out in a form conforming to ASTM D256 and D790, and bending strength, bending elastic modulus and Charpy (flatwise) impact strength are measured at each n = 3. It was. The average value is shown in Table 1.
[0037]
Example 4
Using monofilaments with an average diameter of 13 μm, 16 glass fiber strands with 600 filaments (number of bundles) are bundled and introduced into acid-modified molten polypropylene (260 ° C.) with MI = 40 to perform melt impregnation. After that, it was pulled out from the nozzle of the die having an inner diameter of 2.2 mm at a speed of 30 m / min, and further cut with a pelletizer to a length of 20 mm to obtain an LFRTP base material. The obtained LFRTP base material had an average diameter of 2.2 mm, a glass content of 45.5% by volume, and a resin impregnation rate of 98% as an average value of n = 5. In the above, n represents the number of measurements. The obtained LFRTP base material and non-reinforced polypropylene resin (MI = 40) were dry blended and mixed so that the glass content was 19.3 vol%.
[0038]
This mixture is plasticized by a heating and conveying machine equipped with an inline screw type (cylinder diameter 90 mm, compression ratio 1.4, extrusion port diameter 90 mm) with a shutter mechanism at the tip and no backflow prevention ring. Was made. In addition, the measurement of the average length of the fibers in the melt was performed by burning out the melt at 600 ° C., then arbitrarily selecting 100 monofilaments of the remaining glass fibers, measuring the average value, and measuring 8.2 mm. Measurements were obtained. The average fiber length was 41% of the original LFRTP substrate length. Thereafter, a molded body is obtained in the same manner as in Example 1, and a test piece is cut out in a form conforming to ASTM D256 and D790, and bending strength, bending elastic modulus and Charpy (flatwise) impact strength are measured at each n = 3. It was. The average value is shown in Table 1.
[0039]
Comparative Example 1
Using monofilaments with an average diameter of 13 μm, 30 glass fiber strands with 600 filaments (number of bundles) are bundled and introduced into acid-modified molten polypropylene (260 ° C.) with MI = 40 to perform melt impregnation. After that, the LFRTP substrate was obtained by pulling out from the nozzle of the die having an inner diameter of 3.0 mm at a speed of 15 m / min, and further cutting with a pelletizer so that the length became 20 mm. The obtained LFRTP base material had an average diameter of 3.0 mm, a glass content of 45.5% by volume, and a resin impregnation rate of 94% as an average value of n = 5. In the above, n represents the number of measurements.
[0040]
Subsequently, the obtained LFRTP base material was put into a cylinder having an inner diameter of 90 mm and provided with a shutter mechanism at the tip of the extrusion port and heated to 230 ° C., and plasticized. The molten mass was produced by pushing the melt with a plunger, the shutter was opened, and the molten mass was taken out by further pushing the plunger.
[0041]
In addition, the measurement of the average length of the fiber in a melt is a measurement value of 19 mm by measuring 100 monofilaments of the remaining glass fiber arbitrarily after burning off the melt at 600 ° C. and measuring the average value. Got. The average fiber length was 95% of the original LFRTP substrate length. Thereafter, a molded body is obtained in the same manner as in Example 1, and a test piece is cut out in a form conforming to ASTM D256 and D790, and bending strength, bending elastic modulus and Charpy (flatwise) impact strength are measured at each n = 3. It was. The average value is shown in Table 1.
[0042]
Comparative Example 2
The LFRTP base material obtained in Comparative Example 1 and a non-reinforced polypropylene resin (MI = 40) were dry blended and mixed so that the glass content was 19.3 vol%.
[0043]
This mixture was plasticized with a heating and conveying machine having an inline screw type injection function similar to that in Example 4 to prepare a molten lump. In addition, the measurement of the average length of the fibers in the melt was performed by burning the melt at 600 ° C., and then arbitrarily selecting 100 monofilaments of the remaining glass fibers, measuring the average value, and measuring 7.0 mm. Measurements were obtained. The average fiber length was 35% of the original LFRTP substrate length. Thereafter, a molded body is obtained in the same manner as in Example 1, and a test piece is cut out in a form conforming to ASTM D256 and D790, and bending strength, bending elastic modulus and Charpy (flatwise) impact strength are measured at each n = 3. It was. The average value is shown in Table 1.
[0044]
Comparative Example 3
The LFRTP base material obtained in Comparative Example 1 and a non-reinforced polypropylene resin (MI = 40) were dry blended and mixed so that the glass content was 19.3 vol%. The mixture was plasticized with a heating and conveying machine having a screw pre-pull type injection function similar to that in Example 3 to prepare a molten lump. In addition, the measurement of the average length of the fibers in the melt was performed by burning the melt at 600 ° C., and then arbitrarily selecting 100 monofilaments of the remaining glass fibers, measuring the average value, and measuring 6.8 mm. Measurements were obtained. The average fiber length was 34% of the original LFRTP substrate length. Thereafter, a molded body is obtained in the same manner as in Example 1, and a test piece is cut out in a form conforming to ASTM D256 and D790, and bending strength, bending elastic modulus and Charpy (flatwise) impact strength are measured at each n = 3. It was. The average value is shown in Table 1.
[0045]
Comparative Example 4
The LFRTP base material obtained in Comparative Example 1 and a non-reinforced polypropylene resin (MI = 40) were dry blended and mixed so that the glass content was 19.3 vol%. This mixture is plasticized using a heating and conveying machine equipped with an in-line type (cylinder diameter 90 mm, compression ratio 2.4, extrusion port diameter 5.0 mm) equipped with a backflow prevention ring to create a molten lump. did. In addition, the measurement of the average length of the fiber in a melt is a measurement of 2.8 mm by arbitrarily selecting 100 monofilaments of the remaining glass fiber after burning the melt at 600 ° C. and measuring the average value. Got the value. The average fiber length was 14% of the original LFRTP substrate length. Thereafter, a molded body is obtained in the same manner as in Example 1, and a test piece is cut out in a form conforming to ASTM D256 and D790, and bending strength, bending elastic modulus and Charpy (flatwise) impact strength are measured at each n = 3. It was. The average value is shown in Table 1.
[0046]
Comparative Example 5
The same LFRTP substrate as in Example 1 was uniformly dispersed, and once with a flat plate press, 5 kg / cm.²After creating a 3.8 mm thick sheet by pressing at a pressure of 176 mm, a sheet-shaped preform formed in a length of 176 mm and a width of 176 mm was created, and this sheet was sufficiently heated, the same as used in the examples. 150 kg / cm²The LFRTP molded body was obtained by pressing at a pressure of 1 min. Test pieces were cut out according to ASTM D256 and D790, and the bending strength, bending elastic modulus, and Charpy (flatwise) impact strength were measured at each n = 3. The average value is shown in Table 1. In this method, the production efficiency is inferior because the sheet forming process is performed as described above.
[0047]

[0048]

[0049]
【The invention's effect】
According to the present invention, by heating and conveying the LFRTP base material without applying much shear, it becomes possible to hold the fibers in the molded body for a long time, and improve the mechanical strength, particularly the impact strength, of the molded body. In addition, it is possible to improve the fluidity of the melt during molding by reducing the formation of fibers into monofilaments.
Furthermore, in the present invention, since the molding is performed without a heating process, the heat deterioration of the resin is suppressed, and the complicated work of the conventional technique of moving the softened molten sheet to a plurality of molds is unnecessary. To do.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating a method of the present invention.

Claims

An LFRTP molded body in which a long fiber reinforced thermoplastic resin (LFRTP) base material alone or the base material is diluted with a non-reinforced resin and melted to prepare a melt, and the melt is supplied to a mold and press-molded. In the manufacturing method of
The LFRTP base material has one or more continuous reinforcing fiber strands impregnated with a thermoplastic resin, drawn from a nozzle, and cut to a length of 10 to 50 mm, a diameter or thickness of 0.05 to 2.5 mm, a reinforcing fiber It is an LFRTP base material with a content of 15 to 80% by volume and a thermoplastic resin impregnation rate of 95% or more,
It has a cylinder with a diameter equal to or greater than the length of the LFRTP base material, the squeezing rate of the extrusion port at the tip is 1.0 to 100, the diameter of the extrusion port is at least the length of the LFRTP base material, and the tip of the extrusion port Using a plunger extruder equipped with a shutter mechanism, the LFRTP base material is heated and conveyed, and the average length of the reinforcing fibers in the melt is 40% or more of the original LFRTP base material length. A method for producing an LFRTP molded article, comprising producing and molding a product.

An LFRTP molded body in which a long fiber reinforced thermoplastic resin (LFRTP) base material alone or the base material is diluted with a non-reinforced resin and melted to prepare a melt, and the melt is supplied to a mold and press-molded. In the manufacturing method of
The LFRTP base material is impregnated with one or more continuous reinforcing fiber strands with a thermoplastic resin, drawn from a nozzle, and cut into a length of 10 to 50 mm or a thickness of 0.05 to 2.5 mm, containing reinforcing fibers LFRTP base material having a rate of 15 to 80% by volume and a thermoplastic resin impregnation rate of 95% or more,
It has a cylinder diameter that is longer than the length of the LFRTP base material, has an inline screw type injection function with a shutter mechanism at the tip of the extrusion port, and has a compression ratio of 1.1 to 1.8 at the plasticizing part. The squeezing rate of the extrusion port is 1.0 to 100, the diameter of the extrusion port is equal to or larger than the length of the LFRTP base material, and the heating and conveying machine not provided with the backflow prevention ring is used. And producing a melt in which the average length of reinforcing fibers in the melt is 40% or more of the original LFRTP substrate length, and molding the melt. .

An LFRTP molded body in which a long fiber reinforced thermoplastic resin (LFRTP) base material alone or the base material is diluted with a non-reinforced resin and melted to prepare a melt, and the melt is supplied to a mold and press-molded. In the manufacturing method of
The LFRTP base material is impregnated with one or more continuous reinforcing fiber strands with a thermoplastic resin, drawn from a nozzle, and cut into a length of 10 to 50 mm or a thickness of 0.05 to 2.5 mm, containing reinforcing fibers LFRTP base material having a rate of 15 to 80% by volume and a thermoplastic resin impregnation rate of 95% or more,
It has a cylinder diameter greater than the length of the LFRTP base material, has a screw pre-pull type injection function with a shutter mechanism at the tip of the extrusion port, and has a compression ratio of 1.1 to 1.8 in the plasticizing part, The LFRTP substrate is heated and conveyed using a heating and conveying machine having a diameter of the extrusion port of 1.0 to 100 and the diameter of the extrusion port having a diameter equal to or greater than the length of the LFRTP substrate. A method for producing an LFRTP molded article, comprising producing and molding a melt in which the average length of reinforcing fibers is 40% or more of the original LFRTP base material length.

The method for producing an LFRTP molded body according to any one of claims 1 to 3, wherein the diameter or thickness of the LFRTP base material is 0.05 to 1.5 mm .