JP4283027B2 - Polypropylene resin composition and foamed molded body thereof - Google Patents
Polypropylene resin composition and foamed molded body thereof Download PDFInfo
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- JP4283027B2 JP4283027B2 JP2003103935A JP2003103935A JP4283027B2 JP 4283027 B2 JP4283027 B2 JP 4283027B2 JP 2003103935 A JP2003103935 A JP 2003103935A JP 2003103935 A JP2003103935 A JP 2003103935A JP 4283027 B2 JP4283027 B2 JP 4283027B2
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- 239000004743 Polypropylene Substances 0.000 title claims description 55
- 229920001155 polypropylene Polymers 0.000 title claims description 55
- -1 Polypropylene Polymers 0.000 title claims description 43
- 239000011342 resin composition Substances 0.000 title claims description 21
- 239000000203 mixture Substances 0.000 claims description 26
- 239000004088 foaming agent Substances 0.000 claims description 17
- 239000000454 talc Substances 0.000 claims description 16
- 229910052623 talc Inorganic materials 0.000 claims description 16
- 239000004711 α-olefin Substances 0.000 claims description 14
- 238000002347 injection Methods 0.000 claims description 13
- 239000007924 injection Substances 0.000 claims description 13
- 229920000089 Cyclic olefin copolymer Polymers 0.000 claims description 12
- 239000000155 melt Substances 0.000 claims description 11
- 239000011347 resin Substances 0.000 claims description 11
- 229920005989 resin Polymers 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 8
- 238000010097 foam moulding Methods 0.000 claims description 7
- 238000001746 injection moulding Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 4
- 238000005187 foaming Methods 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 2
- 238000003892 spreading Methods 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 claims 1
- 229920001577 copolymer Polymers 0.000 description 11
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 5
- 239000005977 Ethylene Substances 0.000 description 5
- 239000006260 foam Substances 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 239000004604 Blowing Agent Substances 0.000 description 4
- 239000004594 Masterbatch (MB) Substances 0.000 description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000013329 compounding Methods 0.000 description 4
- 210000004027 cell Anatomy 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 description 2
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 235000013312 flour Nutrition 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- USVVENVKYJZFMW-ONEGZZNKSA-N (e)-carboxyiminocarbamic acid Chemical compound OC(=O)\N=N\C(O)=O USVVENVKYJZFMW-ONEGZZNKSA-N 0.000 description 1
- ICGLPKIVTVWCFT-UHFFFAOYSA-N 4-methylbenzenesulfonohydrazide Chemical compound CC1=CC=C(S(=O)(=O)NN)C=C1 ICGLPKIVTVWCFT-UHFFFAOYSA-N 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- VJRITMATACIYAF-UHFFFAOYSA-N benzenesulfonohydrazide Chemical compound NNS(=O)(=O)C1=CC=CC=C1 VJRITMATACIYAF-UHFFFAOYSA-N 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 210000000497 foam cell Anatomy 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N n-Octanol Natural products CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- ALIFPGGMJDWMJH-UHFFFAOYSA-N n-phenyldiazenylaniline Chemical compound C=1C=CC=CC=1NN=NC1=CC=CC=C1 ALIFPGGMJDWMJH-UHFFFAOYSA-N 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 0.000 description 1
Description
【0001】
【発明の属する技術分野】
本発明は、射出発泡成形において問題となるスワールマークが低減し、自動車部品等として好適な発泡成形体を製造するのに好適なポリプロピレン樹脂組成物及びその発泡成形体に関する。
【0002】
【従来の技術】
近年、自動車分野においては、燃費向上のために、自動車部品の軽量化が図られており、軽量化の方法としては、製品の薄肉化、製品を発泡成形体で作製するなどの方法がある。発泡剤を配合した組成物を発泡させ、硬化させることにより、軽量の発泡成形体を得ることができるが、発泡成形体表面にはスワールマーク(エアーが湧出したもの)が発生するため、自動車部品を発泡成形体で形成した場合、製品の意匠性が損なわれてしまう。このため、カウンタープレッシャー法などの成形方法を採用することにより、発泡成形体の外観を向上させることが検討されているが、材料面での改良は充分であると言えるものではなかった。
例えば、メルトインデックス(MI)とキャピラリースウェルを規定した樹脂を用いることにより、良好な発泡セル制御が達成されているが(例えば、特許文献1参照)、このMIでは、射出成形品における外観品質及びセル形態を良好に保つことは困難である。また、キャピラリースウェルとせん断粘度(流動性)を規定した樹脂を用いることにより発泡成形体のセル形態を制御し、機械特性に優れる発泡成形体を得ることが開示されているが(例えば、特許文献2参照)、外観品質が充分に満足できる発泡成形体と言えるものではなかった。
【0003】
【特許文献1】
特開平8−231816号公報
【特許文献2】
特開2002−234046号公報
【0004】
【発明が解決しようとする課題】
本発明は、上記事情に鑑みなされたもので、射出発泡成形時に発生するスワールマークが低減し、緻密で均一なセルを有する発泡成形体を得ることができる樹脂組成物を提供することを目的とするものである。
【0005】
【課題を解決するための手段】
本発明者らは、上記課題を解決するために鋭意研究を重ねた結果、特定のメルトインデックス及び特定のキャピラリースウェルを有する樹脂に発泡剤を加えた樹脂組成物により、上記目的が達成さ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。
すなわち、本発明は、(A)ポリプロピレン50〜100質量%、(B)エチレン−α−オレフィン共重合体0〜50質量%、(C)タルク0〜25質量%及び(D)発泡剤からなる樹脂組成物であって、(D)成分の配合量が、(A)、(B)及び(C)成分の合計量100質量部に対して0.3〜2.0質量部であり、(A)成分、(A)成分と(B)成分の混合物及び(A)成分と(B)成分と(C)成分の混合物のいずれかの、230℃において測定したメルトインデックス(MI)が30〜100g/10分であり、190℃、せん断速度1220s-1におけるキャピラリースウェルd/d0 (d:樹脂の広がり径,d0 :ダイス径)が1.8以上であることを特徴とするポリプロピレン樹脂組成物を提供するものである。
【0006】
【発明の実施の形態】
本発明において用いる(A)成分のポリプロピレンとしては、ホモポリプロピレン,ブロックポリプロピレン及びランダムポリプロピレンが挙げられる。ポリプロピレンの配合量は、(A)、(B)及び(C)成分の合計量の50〜100質量%であることを要し、65〜80質量%が好ましい。ポリプロピレンの配合量が50質量%未満であると、キャピラリースウェル及び流動性(MI)の低下により、外観品質の確保が困難となる。
(B)成分のエチレン−α−オレフィン共重合体におけるα−オレフィンとしては、炭素数4〜8のものが好ましく、具体的にはプロピレン、1−ブテン、1−ヘキセン、1−オクテンなどが挙げられる。このエチレン−α−オレフィン共重合体は、外観品質の確保に必要な流動性の確保の点から、JIS−K7210に準拠して190℃、荷重21.18Nにおいて測定したメルトインデックス(MI)が8〜60g/10分であることが好ましく、30〜40g/10分がより好ましい。
エチレン−α−オレフィン共重合体の配合量は、(A)、(B)及び(C)成分の合計量の0〜50質量%であることを要し、10〜25質量%が好ましい。エチレン−α−オレフィン共重合体の配合量が50質量%を超えると、成形品に必要とされる剛性を満足できなくなる。
(C)成分のタルクは、成形品における耐衝撃性の保持の点から、平均粒径が10μm以下のものが好ましく、3〜7μmのものがより好ましい。タルクの配合量は、(A)、(B)及び(C)成分の合計量の0〜25質量%であることを要し、0〜10質量%が好ましい。タルクの配合量が25質量%を超えると、キャピラリースウェルの低下を招き、外観品質を保持することができなくなるとともに、耐衝撃性の低下が起こってしまう。
タルクは、ポリプロピレン等のエチレン−α−オレフィン共重合体と混合することにより、マスターバッチの形態で用いることもできる。タルクの配合量は、エチレン−α−オレフィン共重合体とタルクとの合計量中40〜70質量%が好ましく、50〜65質量%がより好ましい。
【0007】
本発明においては、(A)成分、(A)成分と(B)成分の混合物及び(A)成分と(B)成分と(C)成分の混合物のいずれかの、230℃において測定したメルトインデックス(MI)が30〜100g/10分であり、190℃、せん断速度1220s-1におけるキャピラリースウェルd/d0 (d:樹脂の広がり径,d0 :ダイス径)が1.8以上であることを要する。
上記メルトインデックスが30g/10分未満であると、組成物の流動性を低下させることとなるため、射出発泡成形時にショートショットやスワールマークが発生してしまう。また、100g/10分を超えると、発泡成形体の機械物性(特に耐衝撃性)を低下させることとなるため、ドアパネル等の自動車内装部品の製品規格を満足する製品を得ることが困難となる。このメルトインデックスは、好ましくは40〜80g/10分である。なお、このメルトインデックスは、JIS−K7210に準拠し、230℃、荷重21.18Nて測定する。
上記キャピラリースウェルd/d0 が1.8未満であると、発泡成形体.外観が悪化する。このキャピラリースウェルd/d0 は、好ましくは1.9〜2.5である。なお、このキャピラリースウェルd/d0 は、キャピラリーレオメーターを用い、温度190℃、L/D=20(L:ノズル長さ、D:ノズル径)、せん断速度1220s-1の条件で測定する。
ここで、樹脂のキャピラリースウェルd/d0 が1.8以上であると、発泡成形体の外観は良好となるが、樹脂にはある程度の流動性も必要である。押出し成形用の樹脂のように、キャピラリースウェルd/d0 が高くても、流動性が悪いものを用いると、発泡成形体の外観が悪化するため、成形性と機械物性を両立させるためには、射出成形用の樹脂においては、流動性及びキャピラリースウェルd/d0 の制御が重要となってくる。
【0008】
本発明の組成物において、(B)成分及び(C)成分を配合しない場合は、(A)成分として、メルトインデックス30〜100g/10分、キャピラリースウェルd/d0 が1.8以上のポリプロピレンを用いる。このようなポリプロピレンとしては、例えば、後述する実施例で用いるPP−1(ブロックポリプロピレン,MI=30g/10分,キャピラリースウェル=2.4)やPP−2(ブロックポリプロピレン,MI=90g/10分,キャピラリースウェル=2.4)等が挙げられる。PP−1やPP−2よりもキャピラリースウェルを上げたい場合は、分子量分布を広くすればよく、ブロックポリプロピレンの場合は、共重合部の重量平均分子量を高くしてもよい。
(A)成分に、(B)成分あるいは(B)成分と(C)成分を併用することにより、発泡成形体の機械物性を調整することができる。(A)成分と(B)成分を併用する場合は、例えば、(A)成分としてPP−2、(B)成分としてEOM(エチレン−オクテン共重合体ゴム)(MI=30g/10分,密度=0.860g/cm3 )を用い、(A)成分70〜90質量%、(B)成分10〜30質量%で混合することにより、MI=30〜80g/10分、d/d0 =1.8以上とすることができる。
(A)成分と(B)成分と(C)成分を併用する場合は、例えば、(A)成分としてPP−2、(B)成分としてEOM、(C)成分としてタルク(浅田製粉社製,JM210,平均粒径=6μm)を用い、(A)成分60〜80質量%、(B)成分15〜25質量%、(C)成分5〜15質量%で混合することにより、MI=30〜85g/10分、d/d0 =1.8以上とすることができる。
【0009】
本発明のポリプロピレン樹脂組成物は、上記(A)、(B)及び(C)成分の合計量100質量部に対して、(D)成分の発泡剤を0.3〜2.0質量部、好ましくは0.6〜1.0質量部を配合したものである。発泡剤としては、アゾジカルボン酸アミド、重炭酸ソーダとクエン酸の混合物、オキシビスベンゼンスルフォニルヒドラジド、ベンゼンスルフォニルヒドラジド、P−トルエンスルフォニルヒドラジド、ジアゾアミノベンゼン、アゾビスイソブチロニトリル等の熱分解型化学発泡剤から選ばれる一種又は二種以上を使用することができる。
また、これらの発泡剤は、エチレン−α−オレフィン共重合体と混練して発泡剤マスターバッチの形態で用いることもできる。発泡剤の配合量は、エチレン−α−オレフィン共重合体と発泡剤との合計量中20〜50質量%が好ましく、25〜40質量%がより好ましい。
【0010】
本発明のポリプロピレン樹脂組成物には、本発明の目的を損なわない範囲で、必要に応じて、熱安定剤、抗酸化剤、紫外線吸収剤等の各種添加剤を配合することができる。
本発明の樹脂組成物の製造方法は、特に限定されるものではなく、例えば上記(A)〜(D)成分、及び必要に応じて用いる各種添加剤を、通常の機械的混練法によって混練することにより、本発明の樹脂組成物を製造することができる。また、(C)成分のタルクを用いない場合あるいは(C)成分としてタルクのマスターバッチを用いる場合であって、かつ(D)成分として発泡剤のマスターバッチを用いる場合は、機械的混練を行うことなくドライブレンドにより、本発明の樹脂組成物を製造することができる。
このようにして得られた樹脂組成物を、公知の方法で射出発泡成形することにより、発泡成形体を得ることができる。
【0011】
【実施例】
次に、本発明を実施例によりさらに詳細に説明するが、本発明はこれらの例によってなんら限定されるものではない。なお、ポリプロピレン単独あるいは発泡剤を含まない樹脂組成物のメルトインデックス(MI)及びキャピラリースウェル、並びに発泡剤を添加した樹脂組成物を射出発泡成形して製造した発泡成形体の外観を下記の方法により評価した。
(1)メルトインデックス
JIS−K7210に準拠して測定した。ポリプロピレンについては、温度230℃、荷重21.18Nで測定し、エチレン−オクテン共重合体ゴムについては、温度190℃、荷重21.18Nで測定した。
(2)キャピラリースウェル
キャピラリーレオメーター[(株)東洋精機製作所製,キャピログラフ)を用い、温度190℃、せん断速度1220s-1の条件で測定した。
(3)外観評価
直径250mm、厚さ2mm(センターダイレクトゲート)を射出成形し、樹脂組成物を充填した直後に金型を開くことにより、円板状の発泡成形体を得た。このときの、円板表面に発生したスワールマークの状態を目視により5段階(最良のものが5、最悪のものが1)に分別して採点し、4点以上を○、3点以下を×とした。
【0012】
実施例1
ポリプロピレン(PP−1)[ブロックポリプロピレン(コモノマーはエチレン),MI=30g/10分,キャピラリースウェル=2.4]100質量部と発泡剤[炭酸水素ナトリウム,永和化成工業社製,セルボン]0.9質量部を、混練機にて温度200℃で混練し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0013】
実施例2
ポリプロピレン(PP−2)[ブロックポリプロピレン(コモノマーはエチレン),MI=90g/10分,キャピラリースウェル=2.4]100質量部と実施例1と同じ発泡剤0.9質量部を、混練機にて温度200℃で混練し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0014】
実施例3
ポリプロピレン(PP−2)70質量%及びエチレン−オクテン共重合体ゴム(EOM)(MI=30g/10分)を、混練機にて温度200℃で溶融混合し、得られた組成物についてMI及びキャピラリースウェルを測定した。また、ポリプロピレンとエチレン−オクテン共重合体ゴムの合計量100質量部に対して実施例1と同じ発泡剤0.9質量部を加えて上記と同様に溶融混合し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0015】
実施例4
ポリプロピレン(PP−2)70質量%、実施例3と同様のエチレン−オクテン共重合体ゴム20質量%及びタルク(浅田製粉社製,JM210,平均粒径=6μm)10質量%を、混練機にて温度200℃で溶融混合し、得られた組成物についてMI及びキャピラリースウェルを測定した。また、ポリプロピレンとエチレン−オクテン共重合体ゴムとタルクの合計量100質量部に対して実施例1と同じ発泡剤0.9質量部を加えて上記と同様に溶融混合し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0016】
比較例1
ポリプロピレン(PP−3)[ブロックポリプロピレン(コモノマーはエチレン),MI=30g/10分,キャピラリースウェル=1.3]100質量部と実施例1と同じ発泡剤0.9質量部を、混練機にて温度200℃で混練し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0017】
比較例2
ポリプロピレン(PP−4)[ブロックポリプロピレン(コモノマーはエチレン),MI=90g/10分,キャピラリースウェル=1.4]100質量部と実施例1と同じ発泡剤0.9質量部を、混練機にて温度200℃で混練し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0018】
比較例3
ポリプロピレン(PP−4)70質量%及び実施例3と同様のエチレン−オクテン共重合体ゴム30質量%を、混練機にて温度200℃で溶融混合し、得られた組成物についてMI及びキャピラリースウェルを測定した。また、ポリプロピレンとエチレン−オクテン共重合体ゴムの合計量100質量部に対して実施例1と同じ発泡剤0.9質量部を加えて上記と同様に溶融混合し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0019】
比較例4
ポリプロピレン(PP−4)70質量%、実施例3と同様のエチレン−オクテン共重合体ゴム20質量%及び実施例4と同様のタルク10質量%を、混練機にて温度200℃で溶融混合し、得られた組成物についてMI及びキャピラリースウェルを測定した。また、ポリプロピレンとエチレン−オクテン共重合体ゴムとタルクの合計量100質量部に対して実施例1と同じ発泡剤0.9質量部を加えて上記と同様に溶融混合し、得られた組成物を、温度200℃で射出成形し、外観を評価した。結果を表1に示す。
【0020】
【表1】
【0021】
【0022】
【発明の効果】
本発明のポリプロピレン樹脂組成物は、射出発泡成形において問題となるスワールマークが低減し、自動車部品等として好適な発泡成形体を製造するのに好適な樹脂組成物である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polypropylene resin composition suitable for producing a foamed molded article suitable for automobile parts and the like, which has a reduced swirl mark which is a problem in injection foam molding, and the foamed molded article.
[0002]
[Prior art]
In recent years, in the automobile field, the weight of automobile parts has been reduced in order to improve fuel consumption. As a method for reducing the weight, there are methods such as reducing the thickness of a product and producing the product with a foam molded article. By foaming and curing a composition containing a foaming agent, a lightweight foamed molded product can be obtained. However, swirl marks (those from which air is generated) are generated on the surface of the foamed molded product. When is formed of a foamed molded product, the design of the product is impaired. For this reason, it has been studied to improve the appearance of the foamed molded article by adopting a molding method such as a counter pressure method, but it cannot be said that the improvement in terms of material is sufficient.
For example, good foam cell control is achieved by using a resin that defines a melt index (MI) and a capillary swell (see, for example, Patent Document 1). It is difficult to keep the cell shape good. Further, although it is disclosed that a cell shape of a foam-molded article is controlled by using a capillary swell and a resin that defines shear viscosity (fluidity), and a foam-molded article having excellent mechanical properties is obtained (for example, Patent Documents). 2), it was not a foamed molded article with satisfactory appearance quality.
[0003]
[Patent Document 1]
JP-A-8-231816 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-234046
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin composition that can reduce a swirl mark generated during injection foam molding and obtain a foam molded article having dense and uniform cells. To do.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have achieved the above object by using a resin composition in which a foaming agent is added to a resin having a specific melt index and a specific capillary swell. I found. The present invention has been completed based on such findings.
That is, this invention consists of (A) polypropylene 50-100 mass%, (B) ethylene-alpha-olefin copolymer 0-50 mass%, (C) talc 0-25 mass%, and (D) foaming agent. It is a resin composition, Comprising: The compounding quantity of (D) component is 0.3-2.0 mass parts with respect to 100 mass parts of total amounts of (A), (B), and (C) component, The melt index (MI) measured at 230 ° C. of any one of the component A), the mixture of the component (A) and the component (B), and the mixture of the component (A), the component (B), and the component (C) is 30 to 30 100 g / 10 min, polypropylene resin having a capillary swell d / d 0 (d: resin spread diameter, d 0 : die diameter) at 190 ° C. and a shear rate of 1220 s −1 is 1.8 or more A composition is provided.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The polypropylene component (A) used in the present invention, host mode polypropylene, block polypropylene and random polypropylene. The compounding quantity of a polypropylene needs to be 50-100 mass% of the total amount of (A), (B), and (C) component, and 65-80 mass% is preferable. When the blending amount of polypropylene is less than 50% by mass, it is difficult to ensure the appearance quality due to a decrease in capillary swell and fluidity (MI).
The α-olefin in the (B) component ethylene-α-olefin copolymer is preferably one having 4 to 8 carbon atoms, specifically, propylene, 1-butene, 1-hexene, 1-octene and the like. It is done. This ethylene-α-olefin copolymer has a melt index (MI) of 8 measured at 190 ° C. and a load of 21.18 N in accordance with JIS-K7210 from the viewpoint of securing the fluidity necessary for securing the appearance quality. It is preferably ˜60 g / 10 minutes, and more preferably 30 to 40 g / 10 minutes.
The compounding quantity of an ethylene-alpha-olefin copolymer needs to be 0-50 mass% of the total amount of (A), (B), and (C) component, and 10-25 mass% is preferable. When the blending amount of the ethylene-α-olefin copolymer exceeds 50% by mass, the rigidity required for the molded product cannot be satisfied.
The component (C) talc preferably has an average particle size of 10 μm or less, more preferably 3 to 7 μm, from the viewpoint of maintaining impact resistance in the molded product. The amount of talc is required to be 0 to 25% by mass of the total amount of components (A), (B) and (C), and 0 to 10% by mass is preferable. When the amount of talc exceeds 25% by mass, the capillary swell is lowered, the appearance quality cannot be maintained, and the impact resistance is lowered.
Talc can also be used in the form of a masterbatch by mixing with an ethylene-α-olefin copolymer such as polypropylene. The blending amount of talc is preferably 40 to 70% by mass and more preferably 50 to 65% by mass in the total amount of the ethylene-α-olefin copolymer and talc.
[0007]
In the present invention, the melt index measured at 230 ° C. is any one of the component (A), the mixture of the components (A) and (B), and the mixture of the components (A), (B), and (C). (MI) is 30 to 100 g / 10 min, and the capillary well d / d 0 (d: resin spreading diameter, d 0 : die diameter) at 190 ° C. and a shear rate of 1220 s −1 is 1.8 or more. Cost.
When the melt index is less than 30 g / 10 minutes, the fluidity of the composition is lowered, and thus short shots and swirl marks are generated during injection foam molding. On the other hand, if it exceeds 100 g / 10 min, the mechanical properties (particularly impact resistance) of the foamed molded product will be reduced, and it will be difficult to obtain a product that satisfies the product standards for automotive interior parts such as door panels. . This melt index is preferably 40 to 80 g / 10 min. This melt index is measured at 230 ° C. and a load of 21.18 N in accordance with JIS-K7210.
When the capillary swell d / d 0 is less than 1.8, the foam molded article. Appearance deteriorates. The capillary swell d / d 0 is preferably 1.9 to 2.5. The capillary well d / d 0 is measured using a capillary rheometer under the conditions of a temperature of 190 ° C., L / D = 20 (L: nozzle length, D: nozzle diameter), and shear rate of 1220 s −1 .
Here, when the capillary swell d / d 0 of the resin is 1.8 or more, the appearance of the foamed molded article is good, but the resin also needs a certain degree of fluidity. Even if the capillary swell d / d 0 is high, such as a resin for extrusion molding, if a material with poor fluidity is used, the appearance of the foamed molded product is deteriorated. Therefore, in order to achieve both moldability and mechanical properties. In the resin for injection molding, control of fluidity and capillary swell d / d 0 is important.
[0008]
In the composition of the present invention, when component (B) and component (C) are not blended, as component (A), polypropylene having a melt index of 30 to 100 g / 10 minutes and a capillary well d / d 0 of 1.8 or more is used. Is used. Examples of such polypropylene include PP-1 (block polypropylene, MI = 30 g / 10 min, capillary swell = 2.4) and PP-2 (block polypropylene, MI = 90 g / 10 min) used in Examples described later. , Capillary swell = 2.4) and the like. In order to raise the capillary swell more than PP-1 or PP-2, the molecular weight distribution may be widened, and in the case of block polypropylene, the weight average molecular weight of the copolymer part may be increased.
By using the component (B) or the component (B) and the component (C) in combination with the component (A), the mechanical properties of the foam molded article can be adjusted. When the component (A) and the component (B) are used in combination, for example, PP-2 as the component (A), EOM (ethylene-octene copolymer rubber) as the component (B) (MI = 30 g / 10 min, density) = 0.860 g / cm 3 ), and mixing at 70 to 90% by mass of component (A) and 10 to 30% by mass of component (B), MI = 30 to 80 g / 10 min, d / d 0 = It can be 1.8 or more.
When (A) component, (B) component, and (C) component are used together, for example, PP-2 as (A) component, EOM as (B) component, talc (manufactured by Asada Flour Milling Co., Ltd., JM210, average particle size = 6 μm), and mixing at (A) component 60-80% by mass, (B) component 15-25% by mass, and (C) component 5-15% by mass, MI = 30˜ 85 g / 10 min, d / d 0 = 1.8 or more.
[0009]
The polypropylene resin composition of the present invention is 0.3 to 2.0 parts by mass of the foaming agent of component (D) with respect to 100 parts by mass of the total amount of components (A), (B) and (C). Preferably, 0.6 to 1.0 parts by mass are blended. As the blowing agent, thermal decomposition type chemical foaming such as azodicarboxylic acid amide, a mixture of sodium bicarbonate and citric acid, oxybisbenzenesulfonyl hydrazide, benzenesulfonyl hydrazide, P-toluenesulfonyl hydrazide, diazoaminobenzene, azobisisobutyronitrile, etc. One or more selected from agents can be used.
Moreover, these foaming agents can be kneaded with an ethylene-α-olefin copolymer and used in the form of a foaming agent master batch. 20-50 mass% is preferable in the total amount of an ethylene-alpha-olefin copolymer and a foaming agent, and, as for the compounding quantity of a foaming agent, 25-40 mass% is more preferable.
[0010]
In the polypropylene resin composition of the present invention, various additives such as a heat stabilizer, an antioxidant, and an ultraviolet absorber can be blended as necessary within the range not impairing the object of the present invention.
The method for producing the resin composition of the present invention is not particularly limited. For example, the above components (A) to (D) and various additives used as necessary are kneaded by an ordinary mechanical kneading method. By this, the resin composition of the present invention can be produced. Further, when the talc of the component (C) is not used or when the master batch of talc is used as the component (C) and the master batch of the foaming agent is used as the component (D), mechanical kneading is performed. The resin composition of the present invention can be produced by dry blending.
A foamed molded article can be obtained by subjecting the resin composition thus obtained to injection foam molding by a known method.
[0011]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. In addition, the melt index (MI) and capillary swell of a resin composition not containing polypropylene alone or containing a foaming agent, and the appearance of a foam molded product produced by injection foam molding of a resin composition to which a foaming agent has been added are as follows. evaluated.
(1) Melt index It measured based on JIS-K7210. For polypropylene, the temperature 230 ° C., measured under a load 21.18 N, ethylene - For octene copolymer rubber, the temperature 190 ° C., as measured by the load weight 21.18 N.
(2) Capillary well Using a capillary rheometer (manufactured by Toyo Seiki Seisakusho, Capillograph), the measurement was performed under conditions of a temperature of 190 ° C. and a shear rate of 1220 s −1 .
(3) Appearance evaluation A disk-shaped foamed molded article was obtained by injection molding with a diameter of 250 mm and a thickness of 2 mm (center direct gate) and opening the mold immediately after filling with the resin composition. At this time, the state of the swirl mark generated on the surface of the disk was visually classified into 5 levels (the best one was 5 and the worst one was 1) and scored. did.
[0012]
Example 1
Polypropylene (PP-1) [block polypropylene (comonomer is ethylene), MI = 30 g / 10 min, capillary swell = 2.4] and 100 parts by mass of foaming agent [sodium hydrogen carbonate, manufactured by Eiwa Chemical Industries, Cellbon] 9 parts by mass was kneaded at a temperature of 200 ° C. with a kneader, and the resulting composition was injection molded at a temperature of 200 ° C. to evaluate the appearance. The results are shown in Table 1.
[0013]
Example 2
100 parts by mass of polypropylene (PP-2) [block polypropylene (comonomer is ethylene), MI = 90 g / 10 min, capillary swell = 2.4] and 0.9 parts by mass of the same blowing agent as in Example 1 were added to the kneader. The mixture obtained was kneaded at a temperature of 200 ° C., and the resulting composition was injection molded at a temperature of 200 ° C. to evaluate the appearance. The results are shown in Table 1.
[0014]
Example 3
70% by mass of polypropylene (PP-2) and ethylene-octene copolymer rubber (EOM) (MI = 30 g / 10 min) were melt mixed at a temperature of 200 ° C. in a kneader, and MI and Capillary swell was measured. Also, 0.9 parts by mass of the same foaming agent as in Example 1 was added to 100 parts by mass of the total amount of polypropylene and ethylene-octene copolymer rubber, and melt-mixed in the same manner as described above. The appearance was evaluated by injection molding at a temperature of 200 ° C. The results are shown in Table 1.
[0015]
Example 4
70% by mass of polypropylene (PP-2), 20% by mass of the same ethylene-octene copolymer rubber as in Example 3, and 10% by mass of talc (Asada Flour Milling Co., Ltd., JM210, average particle size = 6 μm) were added to a kneader. The mixture was melt-mixed at a temperature of 200 ° C., and MI and capillary well were measured for the obtained composition. Further, 0.9 parts by mass of the same foaming agent as in Example 1 was added to 100 parts by mass of the total amount of polypropylene, ethylene-octene copolymer rubber and talc, and the mixture was melt-mixed in the same manner as above to obtain a composition. Was injection molded at a temperature of 200 ° C. and the appearance was evaluated. The results are shown in Table 1.
[0016]
Comparative Example 1
100 parts by weight of polypropylene (PP-3) [block polypropylene (comonomer is ethylene), MI = 30 g / 10 min, capillary swell = 1.3] and 0.9 parts by weight of the same blowing agent as in Example 1 were added to the kneader. The mixture obtained was kneaded at a temperature of 200 ° C., and the resulting composition was injection molded at a temperature of 200 ° C. to evaluate the appearance. The results are shown in Table 1.
[0017]
Comparative Example 2
100 parts by mass of polypropylene (PP-4) [block polypropylene (comonomer is ethylene), MI = 90 g / 10 min, capillary swell = 1.4] and 0.9 parts by mass of the same blowing agent as in Example 1 were added to the kneader. The mixture obtained was kneaded at a temperature of 200 ° C., and the resulting composition was injection molded at a temperature of 200 ° C. to evaluate the appearance. The results are shown in Table 1.
[0018]
Comparative Example 3
70% by mass of polypropylene (PP-4) and 30% by mass of the same ethylene-octene copolymer rubber as in Example 3 were melt-mixed at a temperature of 200 ° C. in a kneader, and the resulting composition was subjected to MI and capillary swell. Was measured. Also, 0.9 parts by mass of the same foaming agent as in Example 1 was added to 100 parts by mass of the total amount of polypropylene and ethylene-octene copolymer rubber, and melt-mixed in the same manner as described above. The appearance was evaluated by injection molding at a temperature of 200 ° C. The results are shown in Table 1.
[0019]
Comparative Example 4
70% by mass of polypropylene (PP-4), 20% by mass of the same ethylene-octene copolymer rubber as in Example 3 and 10% by mass of talc as in Example 4 were melt mixed at a temperature of 200 ° C. in a kneader. The MI and capillary well were measured for the obtained composition. Further, 0.9 parts by mass of the same foaming agent as in Example 1 was added to 100 parts by mass of the total amount of polypropylene, ethylene-octene copolymer rubber and talc, and the mixture was melt-mixed in the same manner as above to obtain a composition. Was injection molded at a temperature of 200 ° C. and the appearance was evaluated. The results are shown in Table 1.
[0020]
[Table 1]
[0021]
[0022]
【The invention's effect】
The polypropylene resin composition of the present invention is a resin composition suitable for producing a foamed molded article suitable for automobile parts and the like because swirl marks which are problematic in injection foam molding are reduced.
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