JP3831026B2 - Manufacturing method of lightweight molded product of fiber reinforced thermoplastic resin - Google Patents

Manufacturing method of lightweight molded product of fiber reinforced thermoplastic resin Download PDF

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Publication number
JP3831026B2
JP3831026B2 JP28221596A JP28221596A JP3831026B2 JP 3831026 B2 JP3831026 B2 JP 3831026B2 JP 28221596 A JP28221596 A JP 28221596A JP 28221596 A JP28221596 A JP 28221596A JP 3831026 B2 JP3831026 B2 JP 3831026B2
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Japan
Prior art keywords
fiber
weight
molded product
resin
thermoplastic resin
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JP28221596A
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Japanese (ja)
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JPH10119079A (en
Inventor
学 野村
薫 和田
隆義 田中
知和 阿部
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Prime Polymer Co Ltd
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Prime Polymer Co Ltd
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Priority to JP28221596A priority Critical patent/JP3831026B2/en
Application filed by Prime Polymer Co Ltd filed Critical Prime Polymer Co Ltd
Priority to KR10-1998-0706340A priority patent/KR100475398B1/en
Priority to US09/125,037 priority patent/US6010656A/en
Priority to DE1997635855 priority patent/DE69735855T2/en
Priority to AT97902665T priority patent/ATE325695T1/en
Priority to EP97902665A priority patent/EP1008432B1/en
Priority to CN97192313A priority patent/CN1082423C/en
Priority to PCT/JP1997/000371 priority patent/WO1997029896A1/en
Priority to CA 2235881 priority patent/CA2235881A1/en
Publication of JPH10119079A publication Critical patent/JPH10119079A/en
Priority to US09/361,235 priority patent/US6457917B1/en
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Publication of JP3831026B2 publication Critical patent/JP3831026B2/en
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  • Injection Moulding Of Plastics Or The Like (AREA)

Description

【0001】
【発明の属する技術分野】
本発明は、繊維強化熱可塑性樹脂軽量成形品の製造法及び軽量成形品に関し、詳しくは特定の繊維強化熱可塑性樹脂ペレットを用いた射出成形により、軽量で、良好な表面状態を有し、高強度、高剛性である繊維強化熱可塑性樹脂軽量成形品の製造法及び軽量成形品に関する。
【0002】
【従来の技術】
引張強度、剛性、耐熱性を向上させる目的のため、樹脂に種々の繊維を配合することが広く行われているが、繊維の配合量を増やした場合、高強度化は達成されるものの、成形品の比重が高くなるという欠点があった。
一方、軽量な成形体を得る方法としては、成形時に発泡剤を用いる発泡射出成形方法が知られている(特開平7−247679号公報等)が、この場合、軽量化を達成するためにはかなりの量の発泡剤を用いなければならないし、また発泡剤を多く用いたとしても発泡倍率を高くすることもそれほど容易ではなく、十分な軽量化がなされない。さらには、不均一な発泡のために成形品表面外観が劣ったり、内部に大中空部が生じたりして、強度、剛性の点で満足のいく成形品を得ることができなかった。
【0003】
また、樹脂に繊維を配合しつつ、かつ発泡剤を用いて射出成形を行う場合でも上記と同様に、射出成形時、十分な発泡が得られなかったり、成形品表面にシルバーマークのような不良現象が発生したり、強度の点で問題が多く、実用化には至っていないのが現状である。
これらの現状に鑑み、先に本発明者らは、ガラス繊維で強化した成形原料を用い、成形法として、最終の成形品に相当する金型容積よりも小さくなるように閉じた金型中に溶融樹脂を射出し、樹脂の射出完了前若しくは完了後に金型を最終成形品の容積まで開く方法を採ることにより、製品の剛性や耐衝撃性等の強度も大きく、かつ外観も良好で軽量化が達成されたガラス繊維強化熱可塑性樹脂軽量成形品の製造法を提案した(特願平8−277920号)。
【0004】
しかし、かかる方法においては、成形品の軽量化が達成され、表面状態も良好で、かつ剛性等の強度も満足のいくものが得られたものの、繊維としてガラス繊維を用いているため成形時に折れやすく、製品の強度が失われるというおそれもあった。
【0005】
【発明が解決しようとする課題】
本発明は、繊維長の長い特定の繊維含有熱可塑性樹脂ペレットを用いて表面外観、強度、剛性に優れた、軽量の成形品を発泡剤を多量に用いる必要もなく製造する方法及び軽量成形品の提供を目的とする。
【0006】
【課題を解決するための手段】
本発明者らは、軽量化と強度を満足する繊維強化熱可塑性樹脂軽量成形品を射出成形によって得るべく、鋭意検討した結果、特定の成形原料と成形法の組み合わせにより、上記目的が達成されるのみならず、表面外観にも優れた軽量成形品が得られることを見出した。本発明はかかる知見に基づいて完成したものである。
【0007】
【課題を解決するための手段】
すなわち、本発明は、ペレット中の繊維の長さが2〜100mmである繊維含有熱可塑性樹脂ペレット(A)、又は該ペレット(A)と熱可塑性樹脂の混合物を成形原料とし、該ペレット(A)が、100〜10000本の範囲で収束された繊維束に熱可塑性樹脂を含浸させ、溶融樹脂の付着した繊維束を引き抜いて得られたペレットであり、成形原料100重量部に対して、該成形原料中の繊維含有量が30〜80重量%の場合、0.01〜0.8重量部、該成形原料中の繊維含有量が20〜30重量%の場合、0.05〜1.5重量部、該成形原料中の繊維含有量が10〜20重量%の場合、0.1〜5重量部、の発泡剤を配合したものを溶融混練し、固定金型、可動金型、及び、前記可動金型の移動方向と同方向に独立に前進又は後退しうるように前記可動金型の内側に配置された動作コアからなる金型中に、最終の成形品に相等する金型容積よりも小さくなるように閉じた状態で溶融樹脂を射出し、前記動作コアを後退させて拡大することにより、樹脂の射出完了前若しくは完了後に金型を最終成形品の容積まで開いて成形を行い、空隙率30〜80%の軽量成形品を得ることを特徴とする繊維強化熱可塑性樹脂軽量成形品の製造法を提供するものである。
【0008】
【発明の実施の形態】
以下に、本発明の実施の形態を説明する。
1.繊維含有熱可塑性樹脂ペレット(A)
本発明の繊維強化熱可塑性樹脂軽量成形品の製造法においては、繊維含有熱可塑性樹脂ペレット(A)が成形原料として用いられる。
(1) 熱可塑性樹脂
ここで用いられる熱可塑性樹脂については特に制限はなく、例えばポリオレフィン系樹脂,ポリスチレン系樹脂,ポリ塩化ビニル系樹脂,ポリアミド系樹脂,ポリエステル系樹脂,ポリアセタール系樹脂,ポリカーボネート系樹脂,ポリ芳香族エーテル又はチオエーテル系樹脂,ポリ芳香族エステル系樹脂,ポリスルホン系樹脂,アクリレート系樹脂などが挙げられる。
【0009】
ここでポリオレフィン系樹脂としては、例えば、エチレン、プロピレン、ブテン−1、4−メチルペンテン−1などのα−オレフィンの単独重合体やこれらの共重合体、あるいはこれらと他の共重合可能な不飽和単量体との共重合体などが挙げられる。
また、スチレン系樹脂としては、例えば、スチレン,α−メチルスチレンなどの単独重合体やこれらの共重合体、あるいはこれらと共重合可能な不飽和単量体との共重合体が挙げられる。代表例としては、ポリスチレン,シンジオタクチックポリスチレン,アクリロニトリル−ブタジエン−スチレン共重合体(ABS),アクリロニトリル−スチレン共重合体(AS)などが挙げられる。
【0010】
ポリ塩化ビニル系樹脂としては、例えば、塩化ビニル単独重合体や塩化ビニルと共重合可能な不飽和単量体との共重合体などが挙げられる。
ポリアミド系樹脂としては、例えば、6−ナイロン、12−ナイロン、6,6−ナイロン、6,10−ナイロン、6,12−ナイロン、11−ナイロンなどを挙げることができる。
【0011】
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やポリブチレンテレフタレートなどがある。
ポリアセタール系樹脂としては、例えば、単独重合体のポリオキシメチレン及びトリオキサンとエチレンオキシドから得られるホルムアルデヒド−エチレンオキシド共重合体などが挙げられる。
【0012】
ポリカーボネート系樹脂としては、4,4’−ジヒドロキシジアリールアルカン系ポリカーボネート、特にビスフェノールA系ポリカーボネートが好ましく用いられる。また、変性ビスフェノールA系ポリカーボネートや難燃化ビスフェノールA系ポリカーボネートなども用いることができる。
ポリ芳香族エーテル又はチオエーテル系樹脂は、例えば、ポリフェニレンエーテル,スチレンでグラフト化されたポリフェニレンエーテル,ポリエーテルエーテルケトン,ポリフェニレンサルファイドなどが挙げられる。
【0013】
ポリ芳香族エステル系樹脂としては、例えば、ポリアリレートなどが挙げられる。
ポリスルホン系樹脂は、例えば、ポリスルホン、ポリエーテルスルホン、ポリアリールスルホンなどを挙げることができる。
アクリレート系樹脂としては、例えば、メタクリル酸エステル重合体やアクリル酸エステル重合体などが挙げられる。
【0014】
本発明においては、上記熱可塑性樹脂は単独で用いてもよく、二種以上を組み合わせて用いてもよい。また、上記の熱可塑性樹脂の中ではポリプロピレン系樹脂が好ましい。また、不飽和カルボン酸またはその誘導体で変性された酸変性ポリオレフィン系樹脂を含有するポリプロピレン系樹脂も好ましく用いられる。変性に用いられる不飽和カルボン酸またはその誘導体としては、例えば、アクリル酸,メタクリル酸,マレイン酸,フマル酸などの不飽和カルボン酸類、無水マレイン酸などの酸無水物を挙げることができる。これらの中で、特に無水マレイン酸が好適である。
【0015】
これらの不飽和カルボン酸やその誘導体は、前記ポリオレフィン系樹脂を変性する場合、一種用いてもよく、二種以上を組み合わせて用いてもよい。また変性方法については特に制限はなく、従来公知の種々の方法を用いることができる。(2) 繊維
本発明に用いる繊維はガラス繊維以外のものであれば特に問わない。ボロン繊維,炭化ケイ素繊維,アルミナ繊維,チッ化ケイ素繊維,ジルコニア繊維,ケイ酸カルシウム繊維,ロックウール等のセラミック繊維;酸化マグネシウム繊維,マグネシウムオキシサルフェート繊維,水酸化マグネシウム繊維,石膏繊維等の無機繊維;銅繊維,黄銅繊維,鋼繊維,ステンレス繊維,アルミニウム繊維,アルミニウム合金繊維等の金属繊維;ポリエチレン繊維,ポリプロピレン繊維,アラミド繊維,ポリアリレート繊維等の有機繊維;炭素繊維等が挙げられ、好ましくは、セラミック繊維,無機繊維,金属繊維,有機繊維,炭素繊維から選ばれた少なくとも1種であり、2種以上を併用しても構わない。
【0016】
本発明において、繊維としては、その平均繊維径が20μm以下のものが好ましく用いられる。さらに、好ましくは1〜17μm、より好ましくは3〜14μmのものである。1μm未満では、ペレット製造時の樹脂の濡れ、含侵が困難となり、20μmを越えると溶融混練時の繊維の欠損が起こりやすくなるとともに、得られた製品の外観が低下する。
(3) 繊維含有熱可塑性樹脂ペレット(A)の作製方法
繊維含有熱可塑性樹脂ペレット(A)の作製については、特に制限されるものではないが、得られたペレット(A)における繊維の長さが2〜100mm、好ましくは3〜80mm、より好ましくは5〜50mmであることが必要である。繊維長が2mm未満では本発明の製造法を採用しても、十分な膨張が行われないため成形品の軽量化の達成は困難であり、機械的強度も充分でなく、反り変形も大きくなる場合がある。また、100mmを超えると射出成形が困難となるとともに、繊維の分散性が悪くなり、成形品の表面特性が低下する場合がある。
【0017】
ペレット(A)の作製については、例えば、以下に述べる方法が好ましく用いられる。
▲1▼集束された繊維束に熱可塑性樹脂を含浸・付着させる方法
用いる繊維を集束し、そこへ熱可塑性樹脂を含浸させ、溶融樹脂の付着した繊維束(ストランド)を引き抜き、切断することによりペレットを作製する方法であり、例えば、無機繊維や炭素繊維のように比較的折損し易い繊維を用いる場合に好ましく採られる方法である。繊維を適当な収束剤を用いて、好ましくは100〜10000本の範囲で集束した繊維束が用いられる。
【0018】
集束剤としては、例えば、ウレタン系,オレフィン系、アクリル系,ブタジエン系,エポキシ系などがあり、いずれも用いることができるが、これらの中でウレタン系、オレフィン系が好ましい。ウレタン系集束剤は、通常ジイソシアネート化合物と多価アルコールとの重付加反応により得られるポリイソシアネートを50重量%以上の割合で含有するものが好ましく用いられる。また、オレフィン系としては、不飽和カルボン酸またはその誘導体で変性された変性ポリオレフィン系樹脂を用いることができる。
【0019】
このようにして集束された繊維束に熱可塑性樹脂を含浸させることによって繊維含有熱可塑性樹脂ペレット(A)を作製する。繊維束に樹脂を付着、含浸させる方法としては、例えば、溶融樹脂に繊維束を浸漬して通す方法,コーティング用ダイに繊維束を通す方法,ダイを用いて繊維束の周りに溶融樹脂を押し出す方法などを採用することができる。繊維束中への溶融樹脂の含浸、濡れ性をさらに向上させるために、ダイ内に凹凸部を設け、張力下に溶融樹脂の付着した繊維束(ストランド)を引き抜き、さらに加圧ロールでプレスする工程を組み込む引抜成形法も採用することができる。なお、繊維への熱可塑性樹脂の含浸性、ペレットの製造性が満足されれば集束剤の使用は必ずしも必要としない。このようにして得られたストランド状の長繊維含有熱可塑性樹脂を冷却後、適切な長さのペレットに切断することにより、繊維が互いに平行に配列され、繊維長とペレット長とが等しい繊維含有熱可塑性樹脂ペレット(A)を得ることができる。ペレットとして(A)を2〜100mmの長さに切断したものを用いると、繊維の長さはペレット長と等しい2〜100mmとなる。
【0020】
熱可塑性樹脂として、例えば、ポリプロピレン系樹脂が好ましく用いられるが、その場合、メルトインデックス(230℃、2.16kgf)が、10〜1000g/10分の範囲のものが、含侵性、成形性などの点で好ましい。なお、前記ペレットとしては、ストランド状のものを切断したものに限らず、シート状、テープ状、バンド状に成形したものを繊維長さが実質的に2〜100mmになるように切断したものであってもよい。
【0021】
該方法による場合、ペレット(A)中における繊維含有量が20〜80重量%になるように樹脂と繊維を配合するのが好ましい。20重量%未満では、ペレット作製時連続してストランドを引き出せないおそれがあり、80重量%を超えると、繊維束中への樹脂の含浸が悪くなるおそれがある
【0022】
該方法における繊維の量は、熱可塑性樹脂と繊維からなる全体に対し5〜80重量%になるように適宜選べばよい。
該方法による場合、(A)中の繊維はペレット中において互いに平行に配列しているとは必ずしも限らない。
2.繊維強化熱可塑性樹脂軽量成形品の製造法
本発明の繊維強化熱可塑性樹脂軽量成形品の製造法は、前記の繊維含有熱可塑性樹脂ペレット(A)単独、あるいは(A)と熱可塑性樹脂との混合物を成形原料とし、必要に応じて少量の発泡剤を配合したものを、特定条件の射出成形により成形する。
(1) 成形原料
繊維含有熱可塑性樹脂ペレット(A)については前記のとおりであるが、繊維含有量は5〜80重量%、好ましくは5〜60重量%、さらに好ましくは15〜55重量%であることが必要である。繊維含有量の異なるペレットや繊維長の異なるペレットを必要に応じて混合して用いることもできる。繊維含有量の異なるペレットを必要に応じて混合して用いる場合であっても、繊維含有量は全体に対し5〜80重量%、好ましくは5〜60重量%、さらに好ましくは15〜55重量%であることが必要である。
【0023】
また、繊維含有熱可塑性樹脂ペレット(A)と熱可塑性樹脂との混合物を成形原料として用いる場合、該熱可塑性樹脂としては、特に制限はなく、市販されている一般グレードのペレット、粒状体、粉体などその形状には制限はないが、ペレットを用いることが好ましい。この場合においても、(A)と熱可塑性樹脂との混合は制限はないが、(A)と熱可塑性樹脂との混合物からなる成形原料全体に対し、繊維含有量が5〜80重量%、好ましくは5〜60重量%、さら好ましくは15〜55重量%であることが必要である。5重量%未満では、製品の剛性や耐衝撃性が不十分になるおそれがある。また、80重量%以上では、成形品中に未解繊の繊維が残ったり、製品の外観が悪くなる場合がある。
【0024】
またタルク、マイカ、炭酸カルシウムなどの強化剤、充填剤、酸化防止剤、帯電防止剤、難燃剤、顔料、分散剤などを含有していてもよい。
さらに、本発明の軽量成形品の製造法(2)においては、繊維含有熱可塑性樹脂ペレット(A)100重量部、又は繊維含有熱可塑性樹脂ペレット(A)及び熱可塑性樹脂からなる混合物100重量部に対し、発泡剤を0.01〜5重量部配合した配合物が射出成形に供される。0.01重量部より少ない場合、十分な量のガスが発生せず、金型を後退させキャビティを拡大したときに、キャビティ内が負圧状態になり、安定した膨張が行われず、成形品の表面にうねりが生じ平滑性が悪くなったりするおそれがある。5重量部を超える場合、キャビティ内にガスが多くなりすぎ、成形品に空隙部の偏在等が生じ、機械的強度が低下するおそれがある。発泡剤の種類は特に問わないが、熱により分解しガスが発生するものであることが必要である。好ましい発泡剤の量は、発泡剤の種類及び成形に供される原料に含有されている繊維の種類又は量によっても異なるが、一般に、繊維量が30〜80重量%の場合、成形に供される原料100重量部に対し0.01〜0.8重量部であり、繊維量が20〜30重量%の場合、同様に0.05〜1.5重量部であり、繊維量が10〜20重量%の場合、同様に0.1〜5重量部である範囲から選ばれる。
【0025】
発泡剤としては、具体的には、シュウ酸誘導体,アゾ化合物,ヒドラジン誘導体,セミカルバジド,アジ化合物,ニトロソ化合物,トリアゾール,尿素及びその関連化合物,亜硝酸塩,水素化物,炭酸塩及び重炭酸塩等が用いられる。
(2) 成形方法
成形原料の射出成形法としては、▲1▼成形機の加熱筒内に、成形原料を投入し、加熱溶融させた後、繊維等を分散させ、その後射出成形機の先端に送り込み、プランジャー等で射出する方法、▲2▼加熱筒内に、成形原料を投入し、加熱溶融させた後、プランジャー等で射出成形機のスクリュー部に送り込み、繊維等を分散させた後、射出する方法、▲3▼深溝で圧縮比の小さいスクリューを用い、且つシリンダー温度等を著しく高く保ち、繊維破断を防止しつつ射出成形機の先端部分に樹脂を送り込み、プランジャー等で射出成形する方法などがある。ここで、射出成形方法としては、一般の射出成形方法、射出圧縮成形方法を含むものである。本発明の製造法は、上記成形原料を溶融し、最終成形品の容積よりも小さくなるように閉じた金型中に溶融樹脂を射出し、射出完了前若しくは完了後に金型を目的とする最終成形品の容積まで開くことにより行う方法である。
【0026】
この場合の最初の金型の閉じ具合、最終の金型の開き具合は、成形原料の繊維の含有量、繊維長さあるいは目的とする成形品の空隙率(成形体の比重)などをもとに適宜設定することができる。また、金型を開くタイミングは金型の温度、成形品表面のスキン層の厚み、成形品の厚みなどを考慮して適宜決定すればよい。
【0027】
さらには、固定金型,可動金型及び可動金型の移動方向と同方向に独立に前進又は後退しうるように可動金型の内側に配設された動作コアとからなり、キャビティ部が該固定金型,可動金型及び動作コアから形成され、動作コアを前進又は後退させることによりキャビティ部の容積を可変とし得る金型を用いて、最終の成形品における端部形成部を除いた部分を拡大することにより成形をおこなう。即ち、閉じた金型中に溶融樹脂を射出し、樹脂の射出が完了し閉じた金型内へ樹脂が充満される直前、又は樹脂が充満し最終の成形品の端部を形成した後に、キャビティ部分が最終成形品に相等する状態になるように動作コアを後退させることにより成形をおこなう。また、閉じた金型中に溶融樹脂を射出し、樹脂の射出が完了する前に又は完了と同時に、金型内に樹脂が充満するように一旦動作コアを前進させ、樹脂を充満させると同時に又は樹脂を充満させ最終の成形品の端部を形成した後に、キャビティ部分が最終成形品に相等する状態になるように動作コアを後退させてもよい。この方法による場合、低い射出圧力で樹脂の射出を行うことができるため、射出充填時に生じやすい繊維の折損や配向を効果的に防ぐことが可能になる。金型内に樹脂が充満するように一旦動作コアを前進させるが、この場合の前進させる距離を、通常、0.1〜50mmの範囲にするのがよい。特に、成形品表面でのエアーの巻き込みによるフローマーク等の外観不良発生防止の点から、0.1〜10mmの範囲が好ましく用いられる。前進させる速度は、通常、0.5〜30mm/秒の範囲から適宜選ばれる。
【0028】
ここでいう端部とは、最終成形品において、動作コアの後退によって形成される部分以外の部分をさすのであるが、かかる端部を動作コアの後退に先立って形成させることにより、動作コアの後退を開始してもかかる端部の形状はすでに形成されており、動作コアの後退に何ら影響されることなく、端面外観の良好で金型形状に忠実な形状をもつ最終成形品が得ることが可能となる。動作コアを後退させる速度は、用いた樹脂等の成形原料或いは最終成形品の形状等によっても異なるが、通常、0.1〜10mm/秒の範囲で選ばれる。さらには、速度は必ずしも一定にする必要はなく、後退初期から徐々に速度を速めていってもよい。
【0029】
また、動作コアの後退を目的とする最終成形品に相当する位置で停止させるのではなく、一旦最終成形品相当容積よりも大きい位置まで後退させ、しかる後に、最終成形品相当容積にまで動作コアを逆に前進させて圧縮するという方法を採ってもよい。
金型に射出する樹脂の溶融混練物は、繊維が互いに絡み合った状態であることが好ましく、この絡み合いによって射出された溶融樹脂は金型中で膨張性を有する溶融樹脂状態になる。ついで最終成形品の容積になるように金型を開き、冷却することによって最終の軽量成形品が得られる。
【0030】
なお、本発明製造法にあっては目的を阻害しない範囲において、安定剤、帯電防止剤、耐候剤、着色剤などの添加剤を加えることもできる。
さらに、本発明の軽量成形品の製造法にあっては、成形金型の少なくとも一面に、全面または部分的に発泡材料、不織布などの繊維材料、印刷樹脂フイルムなどの表皮材料を予め装着して成形することもできる。
4.繊維強化熱可塑性樹脂軽量成形品
本発明の製造法によって得られる繊維強化熱可塑性樹脂軽量成形品は、繊維含有量は5〜80重量%、好ましくは5〜60重量%、より好ましくは15〜55重量%である。また、その空隙率は30〜80%、好ましくは40〜75%であり、より好ましくは50〜70%である。30%未満では軽量化の効果がなく、80%を越えると空隙を有さないスキン層を確実に形成することが困難になるとともに、強度が十分でなくなる場合がある。なお、ここで空隙率とは、成形品中の繊維や樹脂などの占める容積を除いた容積の比率である。
【0031】
本発明の製造法においては、各種軽量成形品の製造が可能である。本発明にかかる繊維強化熱可塑性樹脂軽量成形品は、特に形状や大きさに制限はないが、好適には板状成形品、特に30mm以下の板状系の成形品、型物成形品が含まれる。具体的には、自動車部品(例えば、インパネコア,バンパービーム,ドアステップ,ルーフラック,リアクォーターパネル,エアクリーナーケース,サンシェードなど)、自動二輪車等に搭載されるヘルメット収納用ボックスのように軽量でかつ耐衝撃性,強度が要求されるところに用いられる各種箱状物、家電部品、建築部材(例えば、コンクリートパネル(コンクリート型枠),ケーブルトラフ,壁材,床材など)、ユニットバスの床材、ウォーターパンなどが挙げられる。
【0032】
【実施例】
次に、実施例及び比較例により本発明をさらに詳細に説明するが、本発明はこれによって制限されるものではない。
下記の実施例及び比較例において、成形品の評価及び成形品より切り出した試験片の試験は下記の方法で行った。
〔テスト用円板の評価〕
(a)反り率: 円板(250mm,肉厚tmm)を定盤上に設置し、第一図に示すように左右の両端が定盤から反り上がった距離を求め、次式により反り率を求めた。
【0033】
反り率=(h1 +h2 )/2×250
【0034】
【図1】
(b)曲げ弾性率: JIS K−7203に準拠して測定した。
比曲げ弾性率=曲げ弾性率/比重
(c)成形品の膨張状況: 成形品を目視により評価
〔テスト用矩形板の評価〕
700mm×450mm×肉厚tmmからなるテスト用矩形板について、以下に述べる評価を行った。
(a)熱垂下性: テスト用矩形板の長手部を固定し、120℃のオーブンに24時間放置後取り出し、23℃で1時間放置した後、最も垂 下の大きい部分の垂下量を測定した。
(b)反り量: テスト用矩形板の長手部を固定し、固定部を基準に三次元の各方向の変位を測定し、その変位の内、最も大きな値を反り量とした。
(c)衝撃強さ: テスト用矩形板の長手部を固定した後、1kgの鉄球をある高さから落下させたとき、製品が破壊する高さを測定した。
(d)曲げ弾性率: JIS K−7203に準拠して測定した。
【0035】
比曲げ弾性率=曲げ弾性率/比重
(e)膨張状況: 製品を切断し、厚み方向から観察した
【0038】
実施例1
MI=60のポリプロピレン(出光石油化学(株)製,商品名J−6083H)をダイスの中に押し出す一方、ポリアリレート繊維(クラレ社製,商品名ベクトラン)のロービングをダイスに引き入れ、繊維束へ樹脂を含浸させた後、繊維を引き抜き、冷却後ペレットの長さが12mmになるように切断した。得られたペレット中の繊維量は42重量%であった。
【0039】
このペレット100重量部に対し、発泡剤マスターバッチペレット〔ポリスレンEV−306G(永和化成工業株式会社製):発泡剤含有量=30重量%〕を0.3重量部添加した後、射出成形機(三菱重工業株式会社製:850MGW、出光圧縮ユニット装着)にて、樹脂温度:200℃、金型温度:80℃で、金型( サンシェードの製品型)を用いて射出成形した。予め金型開度が2mmの状態で、2mm厚みに相当する容量の樹脂を射出し、射出が完了した3秒後、金型を6mmになるまで開き、冷却後、肉厚6mmの製品を得た。得られたサンシェードの製品の評価結果を第2表に示す。
【0040】
【表2】

Figure 0003831026
【0041】
〔実施例2〕
実施例1において、ポリアリレート繊維の代わりにカーボン繊維(東レ社製,商品名トレカ)を用いた以外は同様にしてペレットを得た。ペレット中の繊維量は37重量%であった。予め金型開度が3mmの状態で、3mm厚みに相当する容量の樹脂を射出し、射出が完了した1秒後、金型を6mmになるまで開き、冷却後、肉厚6mmの製品を得た以外は実施例1と同様にした。得られた製品の評価結果を第2表に示す。
〔実施例3〕
実施例2において、予め金型開度が3mmの状態で、3mm厚みに相当する容量の樹脂を射出し、射出が完了した3秒後、金型を9mmになるまで開き、冷却後、肉厚9mmの製品を得た以外は実施例2と同様にした。得られた製品の評価結果を第2表に示す。
〔比較例1〕
実施例2において、発泡剤を4重量部にし、予め金型開度が3mmの状態で、3mm厚みに相当する容量の樹脂を射出し、射出が完了した1秒後、金型を10mmになるまで開き、冷却後、肉厚10mmの製品を得た以外は実施例2と同様にした。得られた製品の評価結果を第2表に示す。
〔比較例2〕
二軸押出機を用い、ホッパー口よりMI=60のポリプロピレン(出光石油化学(株)製,商品名J−6083H)を63重量%になるように供給し、樹脂が溶融した後、サイドフィード口より繊維長3mmのカーボン繊維のチョップトストランドを37重量%になるよう供給し、押出混練することによりペレットを得た。得られたペレットに発泡剤は添加せずに、実施例2と同様に射出成形した。得られた製品の評価結果を第2表に示す。
〔比較例3〕
比較例2で得られたペレット100重量部に発泡剤を2重量部添加した以外は実施例3と同様に射出成形した。得られた製品の評価結果を第2表に示す。
【0042】
【発明の効果】
本発明による繊維強化軽量熱可塑性樹脂軽量成形品の製造法は、発泡剤を多量に用いることなく製造することができ、得られた成形体は、軽量であるとともに、表面状態等の外観に優れ、しかも表面にスキン層が形成されるため、繊維の補強と相まって高強度、高剛性である。
【図面の簡単な説明】
【図1】反り率テスト用円板の概略平面図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a fiber-reinforced thermoplastic resin lightweight molded article and a lightweight molded article. Specifically, the injection-molding using a specific fiber-reinforced thermoplastic resin pellet is lightweight, has a good surface state, and has a high The present invention relates to a method for manufacturing a lightweight molded product of fiber-reinforced thermoplastic resin that is strong and highly rigid, and a lightweight molded product.
[0002]
[Prior art]
For the purpose of improving the tensile strength, rigidity, and heat resistance, it is widely practiced to mix various fibers into the resin. However, when the fiber content is increased, high strength is achieved, but molding There was a drawback that the specific gravity of the product was high.
On the other hand, as a method for obtaining a lightweight molded article, a foam injection molding method using a foaming agent at the time of molding is known (Japanese Patent Laid-Open No. 7-247679, etc.). A considerable amount of foaming agent must be used, and even if a large amount of foaming agent is used, it is not so easy to increase the expansion ratio, and sufficient weight reduction cannot be achieved. Furthermore, the surface appearance of the molded product is inferior due to non-uniform foaming, and a large hollow portion is formed inside, and a molded product satisfying in terms of strength and rigidity cannot be obtained.
[0003]
In addition, even when the resin is blended with fibers and injection molding is performed using a foaming agent, as described above, sufficient foaming cannot be obtained at the time of injection molding, or the molded product surface is defective such as a silver mark. At present, the phenomenon has occurred and there are many problems in terms of strength, and it has not been put into practical use.
In view of these current conditions, the present inventors previously used a molding raw material reinforced with glass fiber, and as a molding method, in a mold closed so as to be smaller than the mold volume corresponding to the final molded product. By injecting molten resin and opening the mold to the volume of the final molded product before or after resin injection is completed, the product has high strength such as rigidity and impact resistance, as well as good appearance and light weight. Has been proposed (Japanese Patent Application No. Hei 8-277920).
[0004]
However, in this method, although the weight reduction of the molded product is achieved, the surface condition is good, and the strength such as rigidity is satisfactory, the glass fiber is used as the fiber, so it breaks during molding. It was easy to lose the strength of the product.
[0005]
[Problems to be solved by the invention]
The present invention relates to a method for producing a lightweight molded article excellent in surface appearance, strength and rigidity using a specific fiber-containing thermoplastic resin pellet having a long fiber length without using a large amount of a foaming agent, and a lightweight molded article The purpose is to provide.
[0006]
[Means for Solving the Problems]
As a result of intensive investigations to obtain a lightweight molded product of fiber reinforced thermoplastic resin satisfying weight reduction and strength by injection molding, the above object is achieved by a combination of a specific molding raw material and a molding method. In addition to the above, the inventors have found that a lightweight molded product excellent in surface appearance can be obtained. The present invention has been completed based on such findings.
[0007]
[Means for Solving the Problems]
That is, the present invention uses a fiber-containing thermoplastic resin pellet (A) having a fiber length of 2 to 100 mm in a pellet, or a mixture of the pellet (A) and a thermoplastic resin as a molding raw material, and the pellet (A ) Is a pellet obtained by impregnating a fiber bundle converged in the range of 100 to 10,000 with a thermoplastic resin and pulling out the fiber bundle to which the molten resin is adhered , and with respect to 100 parts by weight of the forming raw material, When the fiber content in the forming raw material is 30 to 80% by weight, 0.01 to 0.8 part by weight. When the fiber content in the forming raw material is 20 to 30% by weight, 0.05 to 1.5% by weight. When the fiber content in the molding raw material is 10 to 20% by weight, melt blended with 0.1 to 5 parts by weight of a foaming agent, a stationary mold, a movable mold, and Advancing or retreating independently in the same direction as the moving mold Injecting the molten resin in a closed state so as to be smaller than the mold volume equivalent to the final molded product in the mold composed of the operating core arranged inside the movable mold By retreating the core and expanding it, the mold is opened up to the volume of the final molded product before or after the resin injection is completed, and a lightweight molded product with a porosity of 30 to 80% is obtained. The present invention provides a method for producing a lightweight molded article of fiber reinforced thermoplastic resin.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
1. Fiber-containing thermoplastic resin pellet (A)
In the method for producing a fiber-reinforced thermoplastic resin lightweight molded article of the present invention, fiber-containing thermoplastic resin pellets (A) are used as a molding raw material.
(1) Thermoplastic resin There is no particular limitation on the thermoplastic resin used here, for example, polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyamide resin, polyester resin, polyacetal resin, polycarbonate resin. , Polyaromatic ether or thioether resins, polyaromatic ester resins, polysulfone resins, acrylate resins, and the like.
[0009]
Here, examples of the polyolefin-based resin include homopolymers of α-olefins such as ethylene, propylene, butene-1, and 4-methylpentene-1, copolymers thereof, and other copolymerizable non-polymerizable resins. Examples thereof include a copolymer with a saturated monomer.
Examples of the styrenic resin include homopolymers such as styrene and α-methylstyrene, copolymers thereof, and copolymers with unsaturated monomers copolymerizable therewith. Typical examples include polystyrene, syndiotactic polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), and the like.
[0010]
Examples of the polyvinyl chloride resin include vinyl chloride homopolymers and copolymers with unsaturated monomers copolymerizable with vinyl chloride.
Examples of the polyamide-based resin include 6-nylon, 12-nylon, 6,6-nylon, 6,10-nylon, 6,12-nylon, and 11-nylon.
[0011]
Examples of the polyester resin include polyethylene terephthalate and polybutylene terephthalate.
Examples of the polyacetal resin include a homopolymer polyoxymethylene and a formaldehyde-ethylene oxide copolymer obtained from trioxane and ethylene oxide.
[0012]
As the polycarbonate resin, 4,4′-dihydroxydiarylalkane polycarbonate, particularly bisphenol A polycarbonate is preferably used. Also, modified bisphenol A-based polycarbonates, flame retardant bisphenol A-based polycarbonates, and the like can be used.
Examples of the polyaromatic ether or thioether-based resin include polyphenylene ether, polyphenylene ether grafted with styrene, polyether ether ketone, and polyphenylene sulfide.
[0013]
Examples of the polyaromatic ester-based resin include polyarylate.
Examples of the polysulfone resin include polysulfone, polyethersulfone, and polyarylsulfone.
Examples of the acrylate resin include methacrylic acid ester polymers and acrylic acid ester polymers.
[0014]
In the present invention, the above thermoplastic resins may be used alone or in combination of two or more. Of the above thermoplastic resins, polypropylene resins are preferred. A polypropylene resin containing an acid-modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof is also preferably used. Examples of the unsaturated carboxylic acid or derivative thereof used for modification include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and acid anhydrides such as maleic anhydride. Of these, maleic anhydride is particularly preferred.
[0015]
These unsaturated carboxylic acids and derivatives thereof may be used singly or in combination of two or more when the polyolefin resin is modified. Moreover, there is no restriction | limiting in particular about the modification | denaturation method, A conventionally well-known various method can be used. (2) Fiber The fiber used in the present invention is not particularly limited as long as it is other than glass fiber. Boron fiber, silicon carbide fiber, alumina fiber, silicon nitride fiber, zirconia fiber, calcium silicate fiber, rock wool and other ceramic fibers; magnesium oxide fiber, magnesium oxysulfate fiber, magnesium hydroxide fiber, gypsum fiber and other inorganic fibers Metal fibers such as copper fiber, brass fiber, steel fiber, stainless steel fiber, aluminum fiber, aluminum alloy fiber; organic fiber such as polyethylene fiber, polypropylene fiber, aramid fiber, polyarylate fiber; carbon fiber, etc., preferably , At least one selected from ceramic fibers, inorganic fibers, metal fibers, organic fibers, and carbon fibers, and two or more types may be used in combination.
[0016]
In the present invention, fibers having an average fiber diameter of 20 μm or less are preferably used. Furthermore, it is preferably 1 to 17 μm, more preferably 3 to 14 μm. If it is less than 1 μm, it becomes difficult to wet and impregnate the resin during the production of pellets, and if it exceeds 20 μm, fiber loss during melt-kneading tends to occur, and the appearance of the obtained product deteriorates.
(3) Production method of fiber-containing thermoplastic resin pellet (A) The production of fiber-containing thermoplastic resin pellet (A) is not particularly limited, but the length of fiber in the obtained pellet (A). Is 2 to 100 mm, preferably 3 to 80 mm, more preferably 5 to 50 mm. If the fiber length is less than 2 mm, even if the production method of the present invention is adopted, sufficient expansion is not performed, so that it is difficult to achieve weight reduction of the molded product, mechanical strength is not sufficient, and warping deformation is increased. There is a case. Moreover, when it exceeds 100 mm, while injection molding becomes difficult, the dispersibility of a fiber worsens and the surface characteristic of a molded article may fall.
[0017]
For producing the pellet (A), for example, the method described below is preferably used.
(1) Method of impregnating and attaching a thermoplastic resin to a bundle of bundled fibers By bundling the fibers to be used, impregnating them with a thermoplastic resin, drawing out and cutting the fiber bundle (strand) to which the molten resin is adhered This is a method for producing pellets, and is preferably employed when using fibers that are relatively easy to break, such as inorganic fibers and carbon fibers. A fiber bundle in which fibers are bundled with an appropriate sizing agent, preferably in the range of 100 to 10,000 is used.
[0018]
Examples of the sizing agent include urethane-based, olefin-based, acrylic-based, butadiene-based, and epoxy-based materials, and any of them can be used. Of these, urethane-based and olefin-based materials are preferable. As the urethane-based sizing agent, one containing usually a polyisocyanate obtained by a polyaddition reaction of a diisocyanate compound and a polyhydric alcohol in a proportion of 50% by weight or more is preferably used. Further, as the olefin type, a modified polyolefin type resin modified with an unsaturated carboxylic acid or a derivative thereof can be used.
[0019]
A fiber-containing thermoplastic resin pellet (A) is produced by impregnating the thus bundled fiber bundle with a thermoplastic resin. Examples of methods for attaching and impregnating resin to the fiber bundle include, for example, a method in which the fiber bundle is immersed in the molten resin, a method in which the fiber bundle is passed through the coating die, and a molten resin is extruded around the fiber bundle using the die. A method etc. can be adopted. In order to further improve the impregnation and wettability of the molten resin into the fiber bundle, an uneven portion is provided in the die, the fiber bundle (strand) to which the molten resin adheres is pulled under tension, and further pressed with a pressure roll. A pultrusion method incorporating a process can also be employed. In addition, if the impregnation property of the thermoplastic resin to the fiber and the manufacturability of the pellet are satisfied, the use of the sizing agent is not necessarily required. The strand-like long fiber-containing thermoplastic resin thus obtained is cooled and then cut into pellets of an appropriate length so that the fibers are arranged in parallel with each other, and the fiber length and the pellet length are equal. A thermoplastic resin pellet (A) can be obtained. If a pellet obtained by cutting (A) into a length of 2 to 100 mm is used, the fiber length is 2 to 100 mm, which is equal to the pellet length.
[0020]
As the thermoplastic resin, for example, a polypropylene resin is preferably used. In that case, a resin having a melt index (230 ° C., 2.16 kgf) in the range of 10 to 1000 g / 10 min is impregnated, moldability, etc. This is preferable. The pellets are not limited to those obtained by cutting strands, but are formed into sheets, tapes, or bands and cut so that the fiber length is substantially 2 to 100 mm. There may be.
[0021]
In the case of this method, it is preferable to mix the resin and the fiber so that the fiber content in the pellet (A) is 20 to 80% by weight. If the amount is less than 20% by weight, the strands may not be continuously drawn out during pellet production. If the amount exceeds 80% by weight, the impregnation of the resin into the fiber bundle may be deteriorated .
[0022]
What is necessary is just to select suitably the quantity of the fiber in this method so that it may become 5 to 80 weight% with respect to the whole which consists of a thermoplastic resin and a fiber.
In the case of this method, the fibers in (A) are not necessarily arranged in parallel in the pellet.
2. Method for Producing Fiber-Reinforced Thermoplastic Resin Lightweight Molded Product The method for producing the fiber-reinforced thermoplastic resin lightweight molded product of the present invention comprises the above-mentioned fiber-containing thermoplastic resin pellet (A) alone or (A) and a thermoplastic resin. A mixture is used as a molding raw material, and a mixture of a small amount of a foaming agent as required is molded by injection molding under specific conditions.
(1) The molding raw material fiber-containing thermoplastic resin pellet (A) is as described above, but the fiber content is 5 to 80% by weight, preferably 5 to 60% by weight, more preferably 15 to 55% by weight. It is necessary to be. Pellets having different fiber contents and pellets having different fiber lengths can be mixed and used as necessary. Even when pellets having different fiber contents are mixed as necessary, the fiber content is 5 to 80% by weight, preferably 5 to 60% by weight, more preferably 15 to 55% by weight based on the whole. It is necessary to be.
[0023]
Moreover, when using the mixture of a fiber containing thermoplastic resin pellet (A) and a thermoplastic resin as a forming raw material, there is no restriction | limiting in particular as this thermoplastic resin, The commercially available general grade pellet, granule, powder Although there is no restriction | limiting in the shape, such as a body, It is preferable to use a pellet. Also in this case, the mixing of (A) and the thermoplastic resin is not limited, but the fiber content is preferably 5 to 80% by weight, preferably based on the entire forming raw material composed of the mixture of (A) and the thermoplastic resin. 5 to 60% by weight, more preferably 15 to 55% by weight. If it is less than 5% by weight, the product may have insufficient rigidity and impact resistance. If it is 80% by weight or more, undefibrated fibers may remain in the molded product or the appearance of the product may be deteriorated.
[0024]
Further, it may contain reinforcing agents such as talc, mica and calcium carbonate, fillers, antioxidants, antistatic agents, flame retardants, pigments, dispersants and the like.
Furthermore, in the manufacturing method (2) of the lightweight molded article of the present invention, 100 parts by weight of the fiber-containing thermoplastic resin pellet (A), or 100 parts by weight of a mixture comprising the fiber-containing thermoplastic resin pellet (A) and the thermoplastic resin. On the other hand, a blend containing 0.01 to 5 parts by weight of a foaming agent is used for injection molding. When the amount is less than 0.01 parts by weight, a sufficient amount of gas is not generated, and when the mold is retracted and the cavity is enlarged, the inside of the cavity is in a negative pressure state and stable expansion is not performed. There is a possibility that undulations may occur on the surface and smoothness may deteriorate. When the amount exceeds 5 parts by weight, the amount of gas in the cavity becomes excessive, and the molded product may be unevenly distributed, resulting in a decrease in mechanical strength. The type of foaming agent is not particularly limited, but it is necessary that the foaming agent be decomposed by heat to generate gas. The preferred amount of foaming agent varies depending on the type of foaming agent and the type or amount of fiber contained in the raw material used for molding, but generally, when the amount of fiber is 30 to 80% by weight, it is used for molding. When the amount of the fiber is from 0.01 to 0.8 parts by weight and the fiber amount is from 20 to 30% by weight, the amount is from 0.05 to 1.5 parts by weight, and the fiber amount is from 10 to 20 parts by weight. In the case of% by weight, it is similarly selected from the range of 0.1 to 5 parts by weight.
[0025]
Specific examples of blowing agents include oxalic acid derivatives, azo compounds, hydrazine derivatives, semicarbazides, azides, nitroso compounds, triazoles, urea and related compounds, nitrites, hydrides, carbonates and bicarbonates. Used.
(2) Molding method The molding material injection molding method is as follows: (1) The molding material is placed in the heating cylinder of the molding machine, heated and melted, and then the fibers are dispersed, and then at the tip of the injection molding machine. (2) Method of injecting with a plunger, etc. (2) After charging the molding raw material into a heating cylinder, heating and melting it, and then feeding it into the screw part of the injection molding machine with a plunger, etc. (3) Injection method, (3) Using a screw with a deep groove and a small compression ratio, keeping the cylinder temperature etc. extremely high, feeding the resin to the tip of the injection molding machine while preventing fiber breakage, and injection molding with a plunger There are ways to do it. Here, the injection molding method includes a general injection molding method and an injection compression molding method. In the manufacturing method of the present invention, the molding raw material is melted, and the molten resin is injected into a mold that is closed so as to be smaller than the volume of the final molded product. This is a method performed by opening up to the volume of the molded product.
[0026]
In this case, the closing condition of the first mold and the opening condition of the final mold are based on the fiber content of the forming raw material, the fiber length, or the porosity of the target molded product (specific gravity of the molded product). Can be set as appropriate. The timing for opening the mold may be appropriately determined in consideration of the temperature of the mold, the thickness of the skin layer on the surface of the molded product, the thickness of the molded product, and the like.
[0027]
Further, the movable mold includes a fixed mold, a movable mold, and an operating core disposed inside the movable mold so as to be able to advance or retract independently in the same direction as the moving direction of the movable mold. A part formed of a fixed mold, a movable mold, and an operating core, and using a mold that can change the volume of the cavity by moving the operating core forward or backward, and excluding the end forming part in the final molded product Molding is performed by enlarging That is, the molten resin is injected into the closed mold, and immediately after the injection of the resin is completed and the resin is filled into the closed mold, or after the resin is filled and the end of the final molded product is formed, Molding is performed by retracting the operating core so that the cavity portion is in a state equivalent to the final molded product. Also, the molten resin is injected into the closed mold, and before or simultaneously with the completion of the injection of the resin, the operating core is once advanced so that the resin fills the mold, and at the same time the resin is filled. Alternatively, after the resin is filled and the end of the final molded product is formed, the operating core may be retracted so that the cavity portion is in a state equivalent to the final molded product. According to this method, since the resin can be injected at a low injection pressure, it is possible to effectively prevent fiber breakage and orientation that are likely to occur during injection filling. The operating core is once advanced so that the resin fills the mold. In this case, the distance to be advanced is usually in the range of 0.1 to 50 mm. In particular, the range of 0.1 to 10 mm is preferably used from the viewpoint of preventing appearance defects such as a flow mark due to air entrainment on the surface of the molded product. The speed to advance is usually selected from the range of 0.5 to 30 mm / second.
[0028]
The term “end” as used herein refers to a portion other than the portion formed by the retraction of the operating core in the final molded product. By forming such an end prior to the retraction of the operating core, the end of the operating core is formed. The shape of the end is already formed even when the retreat is started, and the final molded product having a good end face appearance and faithful to the mold shape can be obtained without being affected by the retreat of the operating core. Is possible. The speed at which the operating core is retracted varies depending on the molding raw material such as the resin used or the shape of the final molded product, but is usually selected in the range of 0.1 to 10 mm / sec. Furthermore, the speed does not necessarily have to be constant, and the speed may be gradually increased from the initial reverse.
[0029]
Also, instead of stopping the operating core at the position corresponding to the final molded product for the purpose, the operating core is temporarily retracted to a position larger than the final molded product equivalent volume, and then the operating core is reached to the final molded product equivalent volume. On the contrary, the method may be adopted in which the compression is performed by advancing.
The melt-kneaded product of the resin injected into the mold is preferably in a state where the fibers are entangled with each other, and the molten resin injected by this entanglement becomes a molten resin state having expandability in the mold. Then, the final lightweight molded product is obtained by opening the mold so as to have the volume of the final molded product and cooling.
[0030]
In the production method of the present invention, additives such as a stabilizer, an antistatic agent, a weathering agent, and a colorant can be added as long as the object is not impaired.
Furthermore, in the method for producing a lightweight molded article of the present invention, a foam material, a fiber material such as a nonwoven fabric, or a skin material such as a printing resin film is preliminarily attached to at least one surface of a molding die. It can also be molded.
4). Fiber reinforced thermoplastic resin lightweight molded article The fiber reinforced thermoplastic resin lightweight molded article obtained by the production method of the present invention has a fiber content of 5 to 80% by weight, preferably 5 to 60% by weight, more preferably 15 to 55%. % By weight. Moreover, the porosity is 30 to 80%, preferably 40 to 75%, and more preferably 50 to 70%. If it is less than 30%, there is no effect of weight reduction. If it exceeds 80%, it is difficult to reliably form a skin layer having no voids, and the strength may not be sufficient. Here, the porosity is the ratio of the volume excluding the volume occupied by fibers, resin, etc. in the molded product.
[0031]
In the production method of the present invention, various lightweight molded products can be produced. The fiber-reinforced thermoplastic resin lightweight molded product according to the present invention is not particularly limited in shape and size, but preferably includes a plate-shaped molded product, particularly a plate-shaped molded product of 30 mm or less, and a molded product. It is. Specifically, it is lightweight like a helmet storage box mounted on automobile parts (for example, instrument panel cores, bumper beams, door steps, roof racks, rear quarter panels, air cleaner cases, sunshades, etc.), motorcycles, etc. Various boxes, home appliance parts, building materials (for example, concrete panels (concrete formwork), cable troughs, wall materials, floor materials, etc.) used for places where impact resistance and strength are required, flooring for unit baths And water pans.
[0032]
【Example】
EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited by this.
In the following Examples and Comparative Examples, the evaluation of the molded product and the test of the test piece cut out from the molded product were performed by the following methods.
[Evaluation of test disc]
(A) Warpage rate: A disc (250 mm, wall thickness tmm) is placed on the surface plate, and the distance at which both the left and right sides warp from the surface plate as shown in Fig. 1 is calculated. Asked.
[0033]
Warpage rate = (h 1 + h 2 ) / 2 × 250
[0034]
[Figure 1]
(B) Flexural modulus: measured in accordance with JIS K-7203.
Specific flexural modulus = flexural modulus / specific gravity (c) Expansion of molded product: Visual assessment of molded product [evaluation of test rectangular plate]
The following evaluation was performed on a test rectangular plate composed of 700 mm × 450 mm × thickness tmm.
(A) Thermal drooping property: The length of the test rectangular plate was fixed, left in an oven at 120 ° C. for 24 hours, taken out, left at 23 ° C. for 1 hour, and the amount of drooping at the largest drooping portion was measured. .
(B) Warpage amount: The longitudinal portion of the test rectangular plate was fixed, the displacement in each of the three-dimensional directions was measured with reference to the fixed portion, and the largest value of the displacement was taken as the warpage amount.
(C) Impact strength: After fixing the longitudinal portion of the test rectangular plate, the height at which the product was destroyed when a 1 kg iron ball was dropped from a certain height was measured.
(D) Flexural modulus: measured in accordance with JIS K-7203.
[0035]
Specific flexural modulus = flexural modulus / specific gravity (e) Expansion condition: The product was cut and observed from the thickness direction .
[0038]
[ Example 1 ]
Polypropylate with MI = 60 (made by Idemitsu Petrochemical Co., Ltd., trade name: J-6083H) is extruded into the die, while roving of polyarylate fiber (made by Kuraray Co., Ltd., trade name: Vectran) is drawn into the die and put into the fiber bundle. After impregnating the resin, the fiber was pulled out and, after cooling, cut so that the length of the pellet was 12 mm. The amount of fibers in the obtained pellets was 42% by weight.
[0039]
After adding 0.3 parts by weight of a foaming agent master batch pellet [Polyslen EV-306G (manufactured by Eiwa Chemical Industry Co., Ltd.): foaming agent content = 30% by weight] to 100 parts by weight of the pellets, an injection molding machine ( (Mitsubishi Heavy Industries, Ltd .: 850 MGW, equipped with an Idemitsu compression unit), the resin temperature was 200 ° C., the mold temperature was 80 ° C., and the mold (sunshade product mold) was used for injection molding. A resin with a volume corresponding to a thickness of 2 mm is injected in advance with the mold opening being 2 mm, and after 3 seconds after the injection is completed, the mold is opened until it reaches 6 mm, and after cooling, a product with a thickness of 6 mm is obtained. It was. Table 2 shows the evaluation results of the obtained sunshade products.
[0040]
[Table 2]
Figure 0003831026
[0041]
[Example 2]
In Example 1 , pellets were obtained in the same manner except that carbon fibers (manufactured by Toray Industries, Inc., trade name Torayca) were used instead of polyarylate fibers. The amount of fibers in the pellets was 37% by weight. A resin with a volume corresponding to a thickness of 3 mm is injected in advance with a mold opening of 3 mm, and 1 second after the injection is completed, the mold is opened until it reaches 6 mm, and after cooling, a product with a thickness of 6 mm is obtained. The procedure was the same as in Example 1 except that. The evaluation results of the obtained product are shown in Table 2.
Example 3
In Example 2 , with a mold opening of 3 mm in advance, a resin having a volume corresponding to 3 mm thickness was injected, 3 seconds after the injection was completed, the mold was opened to 9 mm, and after cooling, the wall thickness was Example 2 was repeated except that a 9 mm product was obtained. The evaluation results of the obtained product are shown in Table 2.
[Comparative Example 1]
In Example 2 , the foaming agent is 4 parts by weight, the mold opening is 3 mm in advance, the resin having a volume corresponding to 3 mm thickness is injected, and 1 second after the injection is completed, the mold becomes 10 mm. And after cooling, the same procedure as in Example 2 was performed except that a product having a thickness of 10 mm was obtained. The evaluation results of the obtained product are shown in Table 2.
[Comparative Example 2]
Using a twin-screw extruder, feed MI = 60 polypropylene (made by Idemitsu Petrochemical Co., Ltd., trade name J-6083H) to 63 wt% from the hopper port, and after the resin has melted, side feed port Further, a chopped strand of carbon fiber having a fiber length of 3 mm was supplied to 37 wt%, and extrusion kneading was performed to obtain a pellet. The obtained pellet was injection-molded in the same manner as in Example 2 without adding a foaming agent. The evaluation results of the obtained product are shown in Table 2.
[Comparative Example 3]
Injection molding was performed in the same manner as in Example 3 except that 2 parts by weight of a foaming agent was added to 100 parts by weight of the pellets obtained in Comparative Example 2 . The evaluation results of the obtained product are shown in Table 2.
[0042]
【The invention's effect】
The method for producing a lightweight molded article of fiber reinforced lightweight thermoplastic resin according to the present invention can be produced without using a large amount of a foaming agent, and the obtained molded product is lightweight and excellent in appearance such as surface condition. In addition, since a skin layer is formed on the surface, it has high strength and high rigidity combined with fiber reinforcement.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of a warp rate test disc.

Claims (1)

ペレット中の繊維の長さが2〜100mmである繊維含有熱可塑性樹脂ペレット(A)、又は該ペレット(A)と熱可塑性樹脂の混合物を成形原料とし、
該ペレット(A)が、100〜10000本の範囲で収束された繊維束に熱可塑性樹脂を含浸させ、溶融樹脂の付着した繊維束を引き抜いて得られたペレットであり、
成形原料100重量部に対して、
該成形原料中の繊維含有量が30〜80重量%の場合、0.01〜0.8重量部、
該成形原料中の繊維含有量が20〜30重量%の場合、0.05〜1.5重量部、
該成形原料中の繊維含有量が10〜20重量%の場合、0.1〜5重量部、
の発泡剤を配合したものを溶融混練し、
固定金型、可動金型、及び、前記可動金型の移動方向と同方向に独立に前進又は後退しうるように前記可動金型の内側に配置された動作コアからなる金型中に、最終の成形品に相等する金型容積よりも小さくなるように閉じた状態で溶融樹脂を射出し、
前記動作コアを後退させて拡大することにより、樹脂の射出完了前若しくは完了後に金型を最終成形品の容積まで開いて成形を行い、空隙率30〜80%の軽量成形品を得ることを特徴とする繊維強化熱可塑性樹脂軽量成形品の製造法。
A fiber-containing thermoplastic resin pellet (A) having a fiber length of 2 to 100 mm in the pellet, or a mixture of the pellet (A) and the thermoplastic resin as a molding raw material,
The pellet (A) is a pellet obtained by impregnating a fiber bundle converged in the range of 100 to 10000 with a thermoplastic resin and drawing out the fiber bundle to which the molten resin is attached,
For 100 parts by weight of the forming raw material,
When the fiber content in the forming raw material is 30 to 80% by weight, 0.01 to 0.8 parts by weight,
When the fiber content in the forming raw material is 20 to 30% by weight, 0.05 to 1.5 parts by weight,
When the fiber content in the forming raw material is 10 to 20% by weight, 0.1 to 5 parts by weight,
Melt-kneaded what blended the foaming agent,
In a mold consisting of a stationary mold, a movable mold, and an operating core arranged inside the movable mold so that it can be advanced or retracted independently in the same direction as the movement direction of the movable mold, The molten resin is injected in a closed state so as to be smaller than the mold volume equivalent to the molded product of
By retracting and expanding the operating core, the mold is opened up to the volume of the final molded product before or after the resin injection is completed, and a lightweight molded product having a porosity of 30 to 80% is obtained. Manufacturing method of lightweight molded product of fiber reinforced thermoplastic resin.
JP28221596A 1996-02-16 1996-10-24 Manufacturing method of lightweight molded product of fiber reinforced thermoplastic resin Expired - Lifetime JP3831026B2 (en)

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JP28221596A JP3831026B2 (en) 1996-10-24 1996-10-24 Manufacturing method of lightweight molded product of fiber reinforced thermoplastic resin
CA 2235881 CA2235881A1 (en) 1996-02-16 1997-02-13 A method of forming a light-weight, fiber-reinforced thermoplastic resin product and a light-weight molded product
DE1997635855 DE69735855T2 (en) 1996-02-16 1997-02-13 METHOD FOR PRODUCING A LIGHT FIBER-REINFORCED ARTICLE OF THERMOPLASTIC RESIN AND LIGHT FORM PRODUCT
AT97902665T ATE325695T1 (en) 1996-02-16 1997-02-13 METHOD FOR PRODUCING A LIGHTWEIGHT FIBER REINFORCED THERMOPLASTIC RESIN ARTICLE AND LIGHTWEIGHT MOLDED PRODUCT
EP97902665A EP1008432B1 (en) 1996-02-16 1997-02-13 A method of forming a light-weight, fiber-reinforced thermoplastic resin product and a light-weight molded product
CN97192313A CN1082423C (en) 1996-02-16 1997-02-13 Method of forming a light-weight, fiber-reinforced thermoplastic resin product and a light-weight molded product
KR10-1998-0706340A KR100475398B1 (en) 1996-02-16 1997-02-13 A method of forming a light-weight, fiber-reinforced thermoplastic resin product and a light-weight molded product
US09/125,037 US6010656A (en) 1996-02-16 1997-02-13 Method of forming a light-weight, fiber-reinforced thermoplastic resin product and a light-weight molded product
PCT/JP1997/000371 WO1997029896A1 (en) 1996-02-16 1997-02-13 A method of forming a light-weight, fiber-reinforced thermoplastic resin product and a light-weight molded product
US09/361,235 US6457917B1 (en) 1996-02-16 1999-07-27 Method of forming a light-weight, fiber-reinforced thermoplastic resin product and a light-weight molded product

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