JP4226393B2 - Sheet pallet - Google Patents

Description

【００２６】
式中、Ｃｐは前記シクロペンタジエニル骨格を有する配位子、Ｘは水素、ハロゲン、炭素数１〜２０のアルキル基、アリールシリル基、アリールオキシ基、アルコキシ基、アミド基、シリルオキシ基等を表し、Ｙは−Ｏ−、−Ｓ−、−ＮＲ−、−ＰＲ−またはＯＲ、ＳＲ、ＮＲ₂、ＰＲ₂からなる群から選ばれる２価中性リガンド、ＺはＳｉＲ₂、ＣＲ₂、ＳｉＲ₂ＳｉＲ₂、ＣＲ₂ＣＲ₂、ＣＲ＝ＣＲ、ＳｉＲ₂ＣＲ₂、ＢＲ₂、ＢＲからなる群から選ばれる２価基を示す。ただし、Ｒは水素または炭素数１〜２０のアルキル基、アリール基、シリル基、ハロゲン化アルキル基、ハロゲン化アリール基、またはＹ、ＺまたはＹとＺの双方からの２個またはそれ以上のＲ基は縮合環系を形成するものである。Ｍは周期律表第ＩＶ族の遷移金属原子を表す。
【００２７】
式１で表される他の周期律表第Ｒ族の遷移金属化合物の例としては、（ｔ−ブチルアミド）（テトラメチルシクロペンタジエニル）−１，２−エタンジイルジルコニウムジクロライド、（ｔ−ブチルアミド）（テトラメチルシクロペンタジエニル）−１，２−エタンジイルチタンジクロライド、（メチルアミド）（テトラメチルシクロペンタジエニル）−１，２−エタンジイルジルコニウムジクロライド、（メチルアミド）（テトラメチルシクロペンタジエニル）−１，２−エタンジイルチタンジクロライド、（エチルアミド）（テトラメチルシクロペンタジエニル）メチレンタンジクロライド、（ｔ−ブチルアミド）ジメチル（テトラメチルシクロペンタジエニル）シランチタンジクロライド、（ｔ−ブチルアミド）ジメチル（テトラメチルシクロペンタジエニル）シランジルコニウムジベンジル、（ベンジルアミド）ジメチル（テトラメチルシクロペンタジエニル）シランチタンジクロライド、（フェニルホスフイド）ジメチル（テトラメチルシクロペンタジエニル）シランチタンジクロライドなどが挙げられる。
【００２８】
本発明でいう助触媒としては、前記周期律表第ＩＶ族の遷移金属化合物を重合触媒として有効になしうる、または触媒的に活性化された状態のイオン性電荷を均衡させうるものをいい、具体的な助触媒としては、有機アルミニウムオキシ化合物のベンゼン可溶のアルミノキサンやベンゼン不溶の有機アルミニウムオキシ化合物、ホウ素化合物、酸化ランタンなどのランタノイド塩、酸化スズ等が挙げられる。これらの中でもアルミノキサンが最も好ましい。
【００２９】
上記触媒は無機または有機の担体に担持して使用されてもよい。該担体としては無機化合物または有機化合物の多孔質酸化物が好ましく、具体的にはＳｉＯ₂、Ａｌ₂Ｏ₃、ＭｇＯ、ＺｒＯ₂、ＴｉＯ₂、Ｂ₂Ｏ₃、ＣａＯ、ＺｎＯ、ＢａＯ、ＴｈＯ₂等またはこれらの混合物か挙げられ、ＳｉＯ₂−Ａｌ₂Ｏ₃、ＳｉＯ₂−Ｖ₂Ｏ₅、ＳｉＯ₂−ＴｉＯ₂、ＳｉＯ₂−Ｖ₂Ｏ₅、ＳｉＯ₂−ＭｇＯ、ＳｉＯ₂−Ｃｒ₂Ｏ₃等が挙げられる。これらの中でもＳｉＯ₂およびＡｌ₂Ｏ₃からなる群から選択された少なくとも１種の成分を主成分とするものが好ましい。また、有機担体としては、熱可塑性樹脂、熱硬化性樹脂のいずれも使用でき、具体的には、粒子状のポリオレフィン、ポリエステル、ポリアミド、ポリ塩化ビニル、ポリ（メタ）アクリル酸メチル、ポリスチレン、ポリノルボルネン、各種天然高分子およびこれらの混合物等が挙げられる。
【００３０】
本発明で使用する有機アルミニウム化合物として、トリエチルアルミニウム、トリイソプロピルアルミニウム等のトリアルキルアルミニウム；ジアルキルアルミニウムハライド；アルキルアルミニウムセスキハライド；アルキルアルミニウムジハライド；アルキルアルミニウムハイドライド、有機アルミニウムアルコキサイド等が挙げられる。
【００３１】
本発明で使用するエチレン（共）重合体（Ｂ）は、前記触媒の存在下、実質的に溶媒の存在しない気相重合法、スラリー重合法、溶液重合法等で製造され、実質的に酸素、水等を断った状態で、ブタン、ペンタン、ヘキサン、ヘプタン等の脂肪族炭化水素、ベンゼン、トルエン、キシレン等の芳香族炭化水素、シクロヘキサン、メチルシクロヘキサン等の脂環族炭化水素等に例示される不活性炭化水素溶媒の存在下で製造される。重合条件は特に限定されないが、重合温度は通常１５〜３５０℃、好ましくは２０〜２００℃、さらに好ましくは５０〜１１０℃であり、重合圧力は低中圧法の場合通常常圧〜７０ｋｇ／ｃｍ²Ｇ、好ましくは常圧〜２０ｋｇ／ｃｍ²Ｇであり、高圧法の場合通常１５００ｋｇ／ｃｍ²Ｇ以下が望ましい。重合時間は低中圧法の場合通常３分〜１０時間、好ましくは５分〜５時間程度が望ましい。高圧法の場合、通常１分〜３０分、好ましくは２分〜２０分程度が望ましい。また、重合は一段重合法はもちろん、水素濃度、モノマー濃度、重合圧力、重合温度、触媒等の重合条件が互いに異なる２段階以上の多段重合法など特に限定されるものではない。
【００３２】
上記触媒で得られる本発明で使用する特定のエチレン（共）重合体（Ｂ）は、（ロ）密度が０．８６〜０．９７ｇ／ｃｍ³、好ましくは０．８９〜０．９５ｇ／ｃｍ³、より好ましくは０．９０〜０．９４ｇ／ｃｍ³の範囲である。密度が０．８６ｇ／ｃｍ³未満では剛性、耐熱性が劣り、０．９７ｇ／ｃｍ³以上では耐衝撃性（低温脆化温度）が十分でない。特に、０．９０〜０．９４ｇ／ｃｍ³の範囲であれば、剛性、耐熱性と耐衝撃性とがバランスされるシートパレットが得られる。また、エチレン（共）重合体（Ｂ）の（ハ）メルトフローレートは０．０１〜５０ｇ／分、好ましくは０．０３〜３０ｇ／分、さらに好ましくは０．１〜１５ｇ／１０分の範囲である。ＭＦＲが０．０１未満では成形加工性が劣り、５０以上では強度が低下する。
【００３３】
さらに、エチレン（共）重合体（Ｂ）の（ニ）分子量分布パラメーター（Ｍｗ／Ｍｎ）は１．８〜３．５、好ましくは２．０〜３．０さらに好ましくは２．２〜２．８の範囲であることが望ましい。Ｍｗ／Ｍｎが１．８未満では成形加工性が劣り、３．５以上では耐衝撃性が劣る。Ｍｗ／Ｍｎが上記範囲にあることにより、従来のエチレン系重合体（Ｃ）と比較して、衝撃強度などの機械的強度が格段に優れるものである。本発明で使用するエチレン（共）重合体（Ｂ）の分子量分布（Ｍｗ／Ｍｎ）の算出方法は、ゲルパーミエイションクロマトグラフィー（ＧＰＣ）により重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）を求め、このＭｗ／Ｍｎを求めるものである。
【００３４】
本発明で使用する（Ｂ）成分で用いられるエチレン（共）重合体の（ホ）組成分布パラメーターＣｂは１．２以下であり、好ましくは１．１５以下、さらに好ましくは１．１以下にあることが望ましい。１．２以上では、（Ｂ）成分のエチレン（共）重合体の機械的強度の格段なる向上効果が望めない虞を生じる。
【００３５】
本発明で使用する（Ｂ）成分で用いられるエチレン（共）重合体の組成分布パラメーターの測定法は下記の通りである。試料に耐熱安定剤を加え、ＯＤＣＢに濃度０．２重量％となるように１３５℃で加熱溶解する。溶液を、けい藻土（セライト５４５）を充填したカラムに移送し、０．１℃／ｍｉｎで２５℃まで冷却し、試料をセライト表面に沈着する。次に、ＯＤＣＢを一定流量で流しながら、カラム温度を５℃きざみに１２０℃まで段階的に昇温し、試料を溶出させ試料を分別する。溶液をメタノールで再沈後、ろ過、乾燥し、各溶出温度の試料を得る。各試料の重量分率および分岐度（炭素数１０００個あたりの分岐数）を測定する。分岐度（測定値）は１３Ｃ−ＮＭＲにより測定し求める。
【００３６】
３０℃から９０℃で採取した各フラクションについては次のような、分岐度の補正を行う。すなわち、溶出温度に対して測定した分岐度をプロットし、相関関係を最小自乗法で直線に近似し、検量線を作成する。この近似の相関係数は十分大きい。この検量線により求めた値を各フラクションの分岐度とする。なお、溶出温度９５℃以上では溶出温度と分岐度に必ずしも直線関係が成立しないのでこの補正は行わない。
【００３７】
次にそれぞれのフラクションの重量分率ｗ_iを、溶出温度５℃当たりの分岐度ｂ_iの変化量（ｂ_i−ｂ_i-1）で割って相対濃度ｃ_iを求め、分岐度に対して相対濃度をプロットし、組成分布曲線を得る。この組成分布曲線を一定の幅で分割し、次式により組成分布パラメーターＣｂを算出する。
【００３８】
【式２】

【００３９】
ここで、Ｃ_jとｂ_jはそれぞれｊ番目の区分の相対濃度と分岐度である。組成分布パラメーターＣｂは試料の組成が均一である場合に１となり、組成分布が広がるに従って値が大きくなる。
【００４０】
ポリマーの組成分布を測定する方法は多くの提案がなされている。例えば特開昭６０−８８０１６号では、試料を溶剤分別して得た各分別試料の分岐数に対して、累積重量分率が特定の分布（対数正規分布）をすると仮定して数値処理を行い、重量平均分岐度（Ｃｗ）と数平均分岐度（Ｃｎ）の比を求めている。この近似計算は、試料の分岐数と累積重量分率が対数正規分布からずれると精度が下がり、市販のＬＬＤＰＥについて測定を行うと相関係数Ｒ²はかなり低く、値の精度は充分でない。また、このＣｗ／Ｃｎの測定法および数値処理法は、本発明のＣｂのそれと異なるが、あえて数値の比較を行えば、Ｃｗ／Ｃｎの値は、Ｃｂよりかなり大きくなる。
【００４１】
本発明で使用する特定のエチレン（共）重合体（Ｂ）は、触媒の活性点が均一であるため分子量分布と組成分布が狭くなり、衝撃強度が優れるものとなる。これらの重合体は、従来のチーグラー型触媒やフィリップス型触媒（以下総称してチーグラー型触媒という）で得られるこれら（Ｃ）成分のエチレン・α−オレフィン共重合体とは性状が異なるものである。
【００４２】
本発明で使用する組成物を形成するエチレン系重合体（Ｃ）成分は、従来のイオン重合法によるチーグラー型触媒またはフィリップス型触媒（以下総称してチーグラー型触媒という）で得られる密度０．８６〜０．９７ｇ／ｃｍ³のエチレン重合体またはエチレン・α−オレフィン共重合体であって、具体的には高密度ポリエチレン（ＨＤＰＥ）、線状中密度ポリエチレン（ＭＤＰＥ）、線状低密度ポリエチレン（ＬＬＤＰＥ）、超低密度ポリエチレン（ＶＬＤＰＥ）等が挙げられる。
【００４３】
上記チーグラー型触媒による高密度・線状中・低密度ポリエチレン（ＨＤＰＥ、ＭＤＰＥ、ＬＬＤＰＥ）は、密度が０．９１〜０．９７ｇ／ｃｍ³、好ましくは０．９１〜０．９６ｇ／ｃｍ³の範囲であり、ＭＦＲが０．０５〜２０ｇ／１０ｍｉｎ、好ましくは０．１〜１０ｇ／１０ｍｉｎ、さらに好ましくは０．３〜１０ｇ／５ｍｉｎの範囲で選択される。Ｍｗ／Ｍｎは特に限定はないが、３．０〜１３、好ましくは３．５〜８の範囲であるのが一般的である。組成分布は特に限定はないが、１．５以上好ましくは２．０以上であるのが一般的である。
【００４４】
また、上記チーグラー型触媒による超低密度ポリエチレン（ＶＬＤＰＥ）は、密度が０．８６〜０．９１ｇ／ｃｍ³未満、好ましくは０．８８〜０．９０５ｇ／ｃｍ³、ＭＦＲは０．０１〜２０ｇ／１０ｍｉｎ、好ましくは０．１〜１０ｇ／１０ｍｉｎの範囲で選択される。該超低密度ポリエチレン（ＶＬＤＰＥ）は、直鎖状低密度ポリエチレン（ＬＬＤＰＥ）とエチレン・α−オレフィン共重合体ゴム（ＥＰＲ、ＥＰＤＭ）との中間の性状を示し、示差走査熱量測定法（ＤＳＣ）による最大ピーク温度（Ｔｍ）が６０℃以上、好ましくは１００℃以上、かつ沸騰ｎ−ヘキサン不溶分が１０重量％以上の性状を有する特定のエチレン・α−オレフィン共重合体であり、少なくともチタンおよび／またはバナジウムを含有する固体触媒成分と有機アルミニウム化合物とからなる触媒を用いて重合され、直鎖状低密度ポリエチレンが示す高結晶部分とエチレン・α−オレフィン共重合体ゴムが示す非晶部分とを合わせ持つ樹脂であって、前者の特徴である機械的強度、耐熱性などと、後者の特徴であるゴム状弾性、耐低温衝撃性などがバランスよく共存している。
【００４５】
上記チーグラー型触媒によるエチレン・α−オレフィン共重合体のα−オレフィンとしては、炭素数３〜１２、好ましくは３〜１０の範囲であって、具体的にはプロピレン、ブテン−１、４−メチルペンテン−１、ヘキセン−１、オクテン−１、デセン−１、ドデセン−１等を挙げることができる。これらα−オレフィンの含有量は３〜４０モル％の範囲で選択されることが好ましい。
【００４６】
本発明のシートパレットの表層の組成は（Ａ）成分０〜９５重量％、好ましくは５０重量％以下、さらに好ましくは３０重量％以下、（Ｂ）成分５〜１００重量％、好ましくは５０重量％以上、さらに好ましくは７０重量％以上、（Ｃ）成分４５重量％まで、好ましくは３５重量％以下、さらに好ましくは３０重量％以下で構成される。耐熱性等を重視する場合には、（Ａ）成分と（Ｂ）成分の２成分で構成されることが好ましいが、耐寒性、加工性、経済性を考慮した場合には（Ｃ）成分を４５重量％までを配合することが望ましい。
【００４７】
上記三成分（Ａ）、（Ｂ）および（Ｃ）の配合方法としては任意の公知技術が使用でき、代表的な例としてはヘンシェルミキサー、押出機、タンブラーなどの通常の混練機を用いて、ドライブレンド、溶融混合などの方法によって行われる。本発明は上記のように（Ａ）、（Ｂ）および（Ｃ）成分を所望の割合で混合した後、共押出し成形法（たとえばＴダイ法）またはカレンダー法などの通常の方法でシート成形される。
【００４８】
本発明のシートパレット１の主層２の厚さは、０．３〜５ｍｍ、好ましくは０．５〜３．５ｍｍの範囲において適宜選択する。シートパレットの主層の厚さが０．３ｍｍ未満においては、シートの剛性などの機械的強度が劣り、また厚さが５ｍｍを超える場合には、本発明において要求される特性は充足されるが、重量が大となり、荷役の自動化や取扱いに支障をきたす懸念がある。また、シートパレット１の表層３，４の厚さは、０．０７〜１．０ｍｍ、好ましくは０．１〜０．６ｍｍの範囲において適宜選択する。表層の厚さが０．０７ｍｍ未満においては、所望の摩擦係数が得られず、また表層の厚さが１．０ｍｍを超えても、それ以上の摩擦係数増大効果は得られない。本発明のシートパレットの形状は、矩形、正方形、楕円形、円形など適宜の形状でよい。
【００４９】
本発明はまた溶融混合時にシート材料中に、カーボンブラック、炭酸カルシウム、シリカ、金属繊維などの各種充てん材または酸化防止剤、難燃化剤、着色剤、帯電防止剤、滑剤、紫外線吸収剤、分散剤など通常の添加剤を必要に応じて配合してもよい。
【００５０】
【実施例】
以下、本発明を実施例および比較例に基づいて具体的に説明するが、本発明はこれらによって限定されるものではない。
【００５１】
（実施例１〜５）
シートパレット１の主層２として、該シートパレットの表層３，４に使用するプロピレン系重合体（Ａ）と同じ成分であるポリプロピレンブロック共重合体（エチレン含有量１１重量％、ＭＦＲ１．５ｇ／１０ｍｉｎ）を用いた。
次に、シートパレット１の表層３，４の組成物にはＡ）、Ｂ）およびＣ）成分として次のものを使用した。
Ａ）成分：（Ａ）ポリプロピレンブロック共重合体（エチレン含有量１１重量％、ＭＦＲ１．５ｇ／１０ｍｉｎ）
【００５２】
Ｂ）成分：
＜エチレン・α−オレフィン共重合体の重合＞
エチレン・ブテン−１共重合体の重合
攪拌機を付した容量３Ｌのステンレス製オートクレーブを窒素置換し１．５Ｌの精製トルエンを入れた。次いで、ブテン−１を１０ｇ添加し、更にビス（ｎ−ブチルシクロペンタジエニル）ジルコニウムジクロライド（Ｚｒとして０．０２ｍモル）メチルアルモキサン〔ＭＡＯ〕（ＭＡＯ／Ｚｒ＝５００〔モル比〕）の混合溶液を加えた後、８０℃に昇温した。次にエチレンを供給して、連続的に重合しつつ圧力を一定に維持して重合を行った。なお、得られたエチレン・ブテン−１共重合体の物性は以下の通りであった。
ＭＦＲ ：１．９ｇ／１０分
密度 ：０．９２３８ｇ／ｃｍ³
融点 ：１１６℃
分子量分布（Ｍｗ／Ｍｎ） ：２．１
組成分布 ：１．０３
【００５３】
Ｃ：チーグラー触媒による線状低密度ポリエチレン（密度＝０．９２５ｇ／ｃｍ³、ＭＦＲ＝２．０ｇ／１０分、Ｍｗ／Ｍｎ＝４．３、組成分布＝１．６、商品名：日石リニレックス、日本石油化学（株）製）
【００５４】
ダイス幅１６００ｍｍの３種３層のＴ−ダイ成形装置（三菱重工社製）を使用し、主層２に上記ポリプロピレンブロック共重合体（エチレン含有量１１重量％、ＭＦＲ１．５ｇ／１０ｍｉｎ）、その両側には上記Ａ）、Ｂ）及びＣ）成分を表１に示される所定の割合となるようにドライブレンドした後、樹脂温度２３５℃、冷却ロール温度１００℃、引取り速度２ｍｍ／ｍｉｎのシート成形条件で、主層２の厚さ０．９ｍｍ、表層３，４の厚さ０．３ｍｍで幅１６００ｍｍのシートを共押出し成形してシートパレット材料を製造した。上記の各種シートパレット材料の配合組成および静止摩擦係数を表１に示した。
静止摩擦係数は傾斜板法（ダンボール紙／シート面）により測定した。
【００５５】
（比較例１）
実施例１〜５のシートパレット１の主層２として用いたものと同じポリプロピレンブロック共重合体（エチレン含有量１１重量％、ＭＦＲ１．５ｇ／１０ｍｉｎ）を用いて、表層３，４を設けずに厚さ０．９ｍｍの単層からなるシートパレット１を形成した。得られたシートパレットについて実施例１〜５と同一条件下で静止摩擦係数を測定し表１に示した。
【００５６】
表１から明らかなように、本発明の実施例においてはいずれもシートパレット１のプロピレン系重合体の主層２に上記Ａ）、Ｂ）およびＣ）成分からなる組成物の表層３，４を設けることにより、プロピレン系重合体の単層からなるシートパレットの比較例に比べて摩擦係数が向上していることが分かる。
【００５７】
【表１】

【００５８】
【発明の効果】
上記のように、本発明のシートパレットはプロピレン系重合体の主層に、プロピレン系重合体、特定のエチレン（共）重合体およびエチレン系重合体の配合組成物を用いた表層を設けることにより、シートのエンボス加工等の粗面化処理を施すことなく、剛性を損なわずに摩擦係数を向上させることができる。すなわち、シートパレットに要求される剛性は、主としてプロピレン系重合体の主層に持たせ、表層のみをプロピレン系重合体、特定のエチレン（共）重合体およびエチレン系重合体の配合組成物で形成することにより、摩擦係数を向上させると共に、従来技術のプロピレン系重合体、特定のエチレン（共）重合体およびエチレン系重合体の単層からなるシートパレットに比べて製造コストが格段に安くなるという効果を奏することができる。
【図面の簡単な説明】
【図１】 本発明に係るシートパレットの斜視図である。
【図２】 本発明に係るシートパレットの断面図である。
【符号の説明】
１：シートパレット、１ａ：タブ、２：シート本体（主層）、３，４：表層。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet pallet used for logistics transportation, and more particularly to a sheet pallet having a large friction coefficient without impairing rigidity.
[0002]
[Prior art]
Along with resource saving in recent years, various sheet pallets have been proposed in the freight distribution field, but as a sheet pallet used for logistics transportation, it was excellent in terms of the balance between rigidity and low temperature impact resistance. As a material for providing a cold-resistant sheet pallet, a sheet pallet formed using a propylene-based polymer, a specific ethylene (co) polymer, and, if desired, a composition comprising an ethylene polymer has been proposed (for example, Patent Documents). 1).
However, a sheet pallet formed of a composition containing these components can provide a cold-resistant sheet pallet that is excellent in the balance between rigidity and low-temperature impact resistance to some extent, but has a drawback of high manufacturing cost. .
[0003]
In addition, for example, a polyolefin-based thermoplastic resin sheet having a thickness of 0.5 to 3.2 mm is formed with a rough surface on at least the upper surface, and the upper surface is formed with a surface rougher than the lower surface, whereby the package cargo When carrying and transporting cargo, the "loading platform" has smoothed cargo handling work by making the static friction coefficient between the upper surface and the cargo higher than the sliding friction coefficient between the lower surface and the platen. Is disclosed (for example, see Patent Document 2).
[0004]
Further, in a sheet pallet made of a polyolefin-based resin that carries a synthetic resin bag as cargo, a tile shape having a smooth flat portion in a specific range formed by embossing the upper surface of the sheet pallet that comes into contact with the resin bag A sheet pallet is disclosed which is formed by embossing with a convex portion and an undersurface having substantially no flat portion (see, for example, Patent Document 3).
Polyolefin resin is used as the material of the sheet pallet disclosed in these conventional techniques, but it is preferable to use polypropylene resin in terms of rigidity.
[0005]
However, the coefficient of friction cannot be increased in the case of a sheet pallet made of a single layer of polypropylene resin.
Therefore, development of a sheet pallet having a large friction coefficient without impairing the rigidity of the sheet pallet used for logistics transportation has been strongly demanded.
[0006]
[Patent Document 1]
JP-A-8-337246
[Patent Document 2]
Japanese Utility Model Publication No. 55-16821
[Patent Document 3]
Japanese Patent Publication No. 7-37259
[0007]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a sheet pallet having a large friction coefficient without impairing the rigidity of the sheet pallet used for physical transportation.
[0008]
[Means for Solving the Problems]
As a result of intensive studies along the above-mentioned purpose, the present inventors have a main layer composed of a propylene-based polymer and a surface layer composed of a specific composition laminated on one or both sides of the main layer. The present inventors have found that a sheet pallet having an improved friction coefficient can be obtained without impairing rigidity, and the present invention has been completed.
That is, the present invention comprises a main layer made of a propylene-based polymer, and a surface layer laminated on one or both sides of the main layer,
(A) 0 to 95% by weight of a propylene polymer,
(B) (i) In the presence of a catalyst containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton as an essential component, ethylene or ethylene and α having 3 to 20 carbon atoms -Obtained by (co) polymerizing olefins; (b) Density of 0.86-0.97 g / cm^Three(C) ethylene having a melt flow rate of 0.01 to 50 g / 10 min, (d) a molecular weight distribution parameter Mw / Mn 1.8 to 3.5, and (e) a composition distribution parameter Cb of 1.2 or less. (Co) polymer 5-100% by weight, and
(C) Ethylene polymer 0 to 45% by weight
A sheet pallet characterized by comprising a composition comprising: (wherein the total amount of components (A), (B) and (C) is 100% by weight).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
FIG. 1 is a perspective view of a sheet pallet 1 according to the present invention, where 1a is a tab. FIG. 2 shows a cross-sectional view of the sheet pallet according to the present invention. Surface layers 3 and 4 are provided on both surfaces of the sheet body (main layer) 2. In the sheet pallet 1 of the present invention, a main layer 2 made of a propylene-based polymer and surface layers 3 and 4 made of a specific composition laminated on one side or both sides of the main layer are provided. The propylene polymer used as the layer 2 is the same component as the propylene polymer (A) used for the surface layers 3 and 4 of the sheet pallet 1 described later.
[0010]
Examples of the propylene polymer (A) used for the surface layers 3 and 4 in the sheet pallet 1 of the present invention include a propylene homopolymer, a copolymer with other α-olefins mainly composed of propylene, and a mixture thereof. From the viewpoint of heat resistance, crystalline propylene homopolymer, propylene / ethylene block copolymer and the like are preferable. The α-olefin content in the propylene / α-olefin copolymer is preferably 1 to 20% by weight. When the α-olefin content is less than 1% by weight, the impact strength is not sufficient. Further, when the α-olefin content exceeds 20% by weight, there is a possibility that the rigidity is low and the sheet is not suitable. The melt flow rate (hereinafter referred to as MFR) of the propylene polymer is preferably in the range of 0.1 to 20 g / 10 min, and particularly preferably 0.3 to 10 g / 10 min. If the MFR is less than 0.1 g / 10 min, the fluidity of the molten resin is poor, the screw power of the extruder becomes too high, and it may be difficult to produce a good sheet. On the other hand, when the MFR exceeds 20 g / 10 min, the molten resin web hangs down, and satisfactory molding cannot be performed, and the strength and other physical properties of the sheet may be reduced.
[0011]
The production of the ethylene (co) polymer (B) used for the surface layers 3 and 4 in the sheet pallet 1 of the present invention is a group IV transition metal compound containing a ligand having the cyclopentadienyl skeleton. And ethylene or ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a catalyst containing a cocatalyst, an organoaluminum compound and / or a carrier as necessary. Moreover, you may use for a catalyst what was obtained by pre-polymerizing ethylene and / or the said alpha olefin in advance with the said catalyst.
[0012]
The α-olefin has 3 to 20 carbon atoms, preferably 3 to 12 carbon atoms. Specifically, propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1, decene- 1, dodecene-1, and the like. The content of these α-olefins is usually 30 mol% or less, preferably 3 to 20 mol%.
[0013]
(I) Cyclopentadi of a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, which is a catalyst for producing the ethylene (co) polymer (B) used in the present invention An enyl skeleton includes a cyclopentadienyl group, a substituted cyclopentadienyl group, and the like. Examples of substituted cyclopentadienyl groups include hydrocarbon groups having 1 to 10 carbon atoms, silyl groups, silyl substituted alkyl groups, silyl substituted aryl groups, cyano groups, cyanoalkyl groups, cyanoaryl groups, halogen groups, haloalkyl groups, halosilyl groups. A substituted cyclopentadienyl group having at least one substituent selected from the group and the like. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may be bonded to each other to form a ring.
[0014]
As said C1-C10 hydrocarbon group, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group etc. are mentioned, Specifically, a methyl group, an ethyl group, n-propyl group, isopropyl group, n -Alkyl groups such as butyl group, isobutyl group, sec-butyl group, t-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group and decyl group; cycloalkyl groups such as cyclopentyl group and cycloalkyl group; Examples include aryl groups such as phenyl group and tolyl group; aralkyl groups such as benzyl group and neophyll group. Among these, an alkyl group is preferable.
[0015]
Preferred examples of the substituted cyclopentadienyl group include methylcyclopentadienyl group, ethylcyclopentadienyl group, n-hexylcyclopentadienyl group, 1,3-dimethylcyclopentadienyl group, 1,3 Specific examples include -n-butylmethylcyclopentadienyl group and 1,3-n-propylmethylethylcyclopentadienyl group. Among these, the substituted cyclopentadienyl group of the present invention is preferably a cyclopentadienyl group substituted with an alkyl group having 3 or more carbon atoms, and particularly preferably a 1,3-substituted cyclopentadienyl group.
[0016]
The substituted cyclopentadienyl group in the case where substituents, that is, hydrocarbons are bonded to each other to form one or more rings, includes an indenyl group, a hydrocarbon group having 1 to 8 carbon atoms (such as an alkyl group), etc. A substituted indenyl group, a naphthyl group, a substituted naphthyl group substituted by a substituent such as a hydrocarbon group having 1 to 8 carbon atoms (such as an alkyl group), a hydrocarbon group having 1 to 8 carbon atoms ( Preferred examples include a substituted fluorenyl group substituted with a substituent such as an alkyl group).
[0017]
Examples of the transition metal of the group IV transition metal compound containing a ligand having a cyclopentadienyl skeleton include zirconium, titanium, hafnium and the like, and zirconium is particularly preferable.
[0018]
The transition metal compound usually has 1 to 3 ligands having a cyclopentadienyl skeleton, and may have two or more ligands bonded to each other via a crosslinking group. Examples of the crosslinking group include an alkylene group having 1 to 4 carbon atoms, an alkylsilanediyl group, and a silanediyl group.
[0019]
As a ligand other than a ligand having a cyclopentadienyl skeleton in the group IV transition metal compound of the periodic table, hydrogen, a hydrocarbon group having 1 to 20 carbon atoms (an alkyl group, Alkenyl group, aryl group, alkylaryl group, aralkyl group, polyenyl group, etc.), halogen, metaalkyl group, metaaryl group and the like.
[0020]
Specific examples of the transition metal compounds of Group IV of the Periodic Table containing a ligand having the cyclopentadienyl skeleton include the following. That is, as monoalkyl metallocenes, bis (cyclopentadienyl) titanium methyl chloride, bis (cyclopentadienyl) titanium phenyl chloride, bis (cyclopentadienyl) zirconium methyl chloride, bis (cyclopentadienyl) zirconium phenyl chloride, etc. There is. Dialkylmetallocenes include bis (cyclopentadienyl) titanium dimethyl, bis (cyclopentadienyl) titanium diphenyl, bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium diphenyl, bis (cyclopentadienyl) ) Hafnium dimethyl, bis (cyclopentadienyl) hafnium diphenyl, and the like. Trialkylmetallocenes include cyclopentadienyl titanium trimethyl, cyclopentadienyl zirconium triphenyl, cyclopentadienyl zirconium trineopentyl, cyclopentadienyl zirconium trimethyl, cyclopentadienyl hafnium triphenyl, cyclopentadienyl hafnium Examples include trineopentyl and cyclopentadienyl hafnium trimethyl.
[0021]
Examples thereof include pentamethylcyclopentadienyl titanium trichloride, pentaethylcyclopentadienyl titanium trichloride, and bis (pentamethylcyclopentadienyl) titanium diphenyl, which are monocyclopentadienyl titanocenes.
[0022]
Substituted bis (cyclopentadienyl) titanium compounds include bis (indenyl) titanium diphenyl or dichloride, bis (methylcyclopentadienyl) titanium diphenyl or halide; dialkyl, trialkyl, tetraalkyl or pentaalkylcyclopentadienyl titanium Compounds include bis (1,2-dimethylcyclopentadienyl) titanium diphenyl or dichloride, bis (1,2-diethylcyclopentadienyl) titanium diphenyl or dichloride or other dihalide complexes, silicon, amine or carbon-linked cyclohexane. Pentadiene complexes include dimethylsilyl dicyclopentadienyl titanium diphenyl or dichloride, methylene dicyclopentadienyl titanium diphenyl. Le or dichloride, and other dihalide complexes.
[0023]
Examples of zirconocene compounds include pentamethylcyclopentadienyl zirconium trichloride, pentaethylcyclopentadienyl zirconium trichloride, bis (pentamethylcyclopentadienyl) zirconium diphenyl; and examples of alkyl-substituted cyclopentadiene include bis (ethylcyclopentadiene). Enyl) zirconium dimethyl, bis (methylcyclopentadienyl) zirconium dimethyl, bis (n-butylcyclopentadienyl) zirconium dimethyl, their haloalkyl or dihalide complexes; dialkyl, trialkyl, tetraalkyl or pentaalkylcyclopentadiene Bis (pentamethylcyclopentadienyl) zirconium dimethyl, bis (1,2-dimethylcyclopentadienyl) zirconi Dimethyl, and their dihalide complexes, silicon, carbon-linked cyclopentadiene complexes include dimethylsilyl dicyclopentadienyl zirconium dimethyl or dihalide, methylene dicyclopentadienyl zirconium dimethyl or dihalide, methylene dicyclopentadienyl zirconium dimethyl or Examples include dihalides.
[0024]
Examples of other group IV transition metal compounds used in the present invention include a ligand having a cyclopentadienyl skeleton represented by the following general formula and other ligands and transition metal atoms in a ring. Can also be formed.
[0025]
[Formula 1]

[0026]
In the formula, Cp is a ligand having the cyclopentadienyl skeleton, X is hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms, an arylsilyl group, an aryloxy group, an alkoxy group, an amide group, a silyloxy group, or the like. Y represents -O-, -S-, -NR-, -PR- or OR, SR, NR₂, PR₂A divalent neutral ligand selected from the group consisting of: Z is SiR₂, CR₂, SiR₂SiR₂, CR₂CR₂, CR = CR, SiR₂CR₂, BR₂And a divalent group selected from the group consisting of BR. Where R is hydrogen or an alkyl group having 1 to 20 carbon atoms, an aryl group, a silyl group, a halogenated alkyl group, a halogenated aryl group, or two or more Rs from Y, Z or Y and Z. Groups form a condensed ring system. M represents a transition metal atom of Group IV of the periodic table.
[0027]
Examples of other transition metal compounds of Group R of the periodic table represented by Formula 1 include (t-butylamide) (tetramethylcyclopentadienyl) -1,2-ethanediylzirconium dichloride, (t-butylamide) ) (Tetramethylcyclopentadienyl) -1,2-ethanediyl titanium dichloride, (methylamide) (tetramethylcyclopentadienyl) -1,2-ethanediylzirconium dichloride, (methylamide) (tetramethylcyclopentadienyl) ) -1,2-ethanediyltitanium dichloride, (ethylamide) (tetramethylcyclopentadienyl) methylenetandichloride, (t-butylamido) dimethyl (tetramethylcyclopentadienyl) silanetitanium dichloride, (t-butylamido) dimethyl (Tetramethyl Cyclopentadienyl) silane zirconium dibenzyl, (benzylamide) dimethyl (tetramethylcyclopentadienyl) silane titanium dichloride, and the like (phenyl phosphine id) dimethyl (tetramethylcyclopentadienyl) silane titanium dichloride.
[0028]
The co-catalyst as used in the present invention refers to a catalyst that can effectively make the transition metal compound of group IV of the periodic table as a polymerization catalyst, or can balance the ionic charge in a catalytically activated state, Specific examples of the co-catalyst include benzene-soluble aluminoxanes of organoaluminum oxy compounds, benzene-insoluble organoaluminum oxy compounds, boron compounds, lanthanoid salts such as lanthanum oxide, tin oxide, and the like. Of these, aluminoxane is most preferred.
[0029]
The catalyst may be used by being supported on an inorganic or organic carrier. The carrier is preferably a porous oxide of an inorganic compound or an organic compound, specifically, SiO.₂, Al₂O_Three, MgO, ZrO₂TiO₂, B₂O_Three, CaO, ZnO, BaO, ThO₂Or a mixture thereof, SiO 2₂-Al₂O_Three, SiO₂-V₂O_Five, SiO₂-TiO₂, SiO₂-V₂O_Five, SiO₂-MgO, SiO₂-Cr₂O_ThreeEtc. Among these, SiO₂And Al₂O_ThreeThe main component is at least one component selected from the group consisting of: As the organic carrier, any of thermoplastic resins and thermosetting resins can be used. Specifically, particulate polyolefin, polyester, polyamide, polyvinyl chloride, poly (meth) acrylate, polystyrene, Examples include norbornene, various natural polymers, and mixtures thereof.
[0030]
Examples of the organoaluminum compound used in the present invention include trialkylaluminums such as triethylaluminum and triisopropylaluminum; dialkylaluminum halides; alkylaluminum sesquihalides; alkylaluminum dihalides; alkylaluminum hydrides and organoaluminum alkoxides.
[0031]
The ethylene (co) polymer (B) used in the present invention is produced by a gas phase polymerization method, a slurry polymerization method, a solution polymerization method or the like substantially free of a solvent in the presence of the catalyst, and is substantially oxygenated. Examples are aliphatic hydrocarbons such as butane, pentane, hexane, and heptane, aromatic hydrocarbons such as benzene, toluene, and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane. Produced in the presence of an inert hydrocarbon solvent. The polymerization conditions are not particularly limited, but the polymerization temperature is usually 15 to 350 ° C., preferably 20 to 200 ° C., more preferably 50 to 110 ° C., and the polymerization pressure is usually normal pressure to 70 kg / cm in the case of the low-medium pressure method.²G, preferably normal pressure to 20 kg / cm²G, usually 1500 kg / cm for high pressure method²G or less is desirable. The polymerization time is usually from 3 minutes to 10 hours, preferably from about 5 minutes to 5 hours in the case of the low and medium pressure method. In the case of the high pressure method, it is usually 1 minute to 30 minutes, preferably about 2 minutes to 20 minutes. In addition, the polymerization is not particularly limited to a one-stage polymerization method, but also a two-stage or more multi-stage polymerization method in which polymerization conditions such as hydrogen concentration, monomer concentration, polymerization pressure, polymerization temperature, and catalyst are different from each other.
[0032]
The specific ethylene (co) polymer (B) used in the present invention obtained with the above catalyst has a (b) density of 0.86 to 0.97 g / cm.^Three, Preferably 0.89-0.95 g / cm^Three, More preferably 0.90 to 0.94 g / cm^ThreeRange. Density is 0.86 g / cm^ThreeIf less, rigidity and heat resistance are inferior, 0.97 g / cm^ThreeAbove, the impact resistance (low temperature embrittlement temperature) is not sufficient. In particular, 0.90 to 0.94 g / cm^ThreeIf it is in the range, a sheet pallet in which rigidity, heat resistance and impact resistance are balanced can be obtained. In addition, the (ha) melt flow rate of the ethylene (co) polymer (B) is 0.01 to 50 g / min, preferably 0.03 to 30 g / min, more preferably 0.1 to 15 g / 10 min. It is. When the MFR is less than 0.01, the moldability is inferior, and when the MFR is 50 or more, the strength decreases.
[0033]
Further, the (d) molecular weight distribution parameter (Mw / Mn) of the ethylene (co) polymer (B) is 1.8 to 3.5, preferably 2.0 to 3.0, more preferably 2.2 to 2. A range of 8 is desirable. When Mw / Mn is less than 1.8, the moldability is inferior, and when it is 3.5 or more, the impact resistance is inferior. When Mw / Mn is in the above range, mechanical strength such as impact strength is remarkably superior to that of the conventional ethylene polymer (C). The molecular weight distribution (Mw / Mn) of the ethylene (co) polymer (B) used in the present invention is calculated by gel permeation chromatography (GPC) by weight average molecular weight (Mw) and number average molecular weight (Mn). This Mw / Mn is obtained.
[0034]
The (e) composition distribution parameter Cb of the ethylene (co) polymer used in the component (B) used in the present invention is 1.2 or less, preferably 1.15 or less, more preferably 1.1 or less. It is desirable. If the ratio is 1.2 or more, there is a possibility that a remarkable improvement effect of the mechanical strength of the ethylene (co) polymer of the component (B) cannot be expected.
[0035]
The measuring method of the composition distribution parameter of the ethylene (co) polymer used in the component (B) used in the present invention is as follows. A heat-resistant stabilizer is added to the sample, and it is dissolved by heating at 135 ° C. to a concentration of 0.2% by weight in ODCB. The solution is transferred to a column packed with diatomaceous earth (Celite 545), cooled to 25 ° C. at 0.1 ° C./min, and the sample is deposited on the celite surface. Next, while flowing ODCB at a constant flow rate, the column temperature is raised stepwise to 120 ° C. in steps of 5 ° C. to elute the sample and separate the sample. The solution is reprecipitated with methanol, filtered and dried to obtain samples at each elution temperature. The weight fraction and the degree of branching (number of branches per 1000 carbon atoms) of each sample are measured. The degree of branching (measured value) is determined by 13C-NMR.
[0036]
For each fraction collected at 30 ° C. to 90 ° C., the degree of branching is corrected as follows. That is, the degree of branching measured against the elution temperature is plotted, the correlation is approximated to a straight line by the method of least squares, and a calibration curve is created. This approximate correlation coefficient is sufficiently large. The value obtained from this calibration curve is taken as the degree of branching of each fraction. If the elution temperature is 95 ° C. or higher, the linear relationship is not necessarily established between the elution temperature and the degree of branching, so this correction is not performed.
[0037]
Next, the weight fraction w of each fraction_iThe degree of branching per elution temperature of 5 ° C._iChange amount (b_i-B_i-1) Divided by relative concentration c_iAnd plot the relative concentration against the degree of branching to obtain a composition distribution curve. This composition distribution curve is divided by a certain width, and the composition distribution parameter Cb is calculated by the following equation.
[0038]
[Formula 2]

[0039]
Where C_jAnd b_jAre the relative concentration and the degree of branching of the jth segment, respectively. The composition distribution parameter Cb is 1 when the composition of the sample is uniform, and increases as the composition distribution increases.
[0040]
Many proposals have been made for methods for measuring the composition distribution of polymers. For example, in JP-A-60-88016, numerical processing is performed on the assumption that the cumulative weight fraction has a specific distribution (logarithmic normal distribution) with respect to the number of branches of each fractionated sample obtained by solvent fractionation of the sample. The ratio of the weight average branching degree (Cw) and the number average branching degree (Cn) is obtained. This approximate calculation is less accurate when the number of sample branches and the cumulative weight fraction deviate from the lognormal distribution.²Is quite low and the accuracy of the value is not sufficient. Further, the Cw / Cn measurement method and the numerical processing method are different from those of Cb of the present invention. However, if the numerical values are compared, the value of Cw / Cn becomes considerably larger than Cb.
[0041]
The specific ethylene (co) polymer (B) used in the present invention has a uniform active site of the catalyst, so that the molecular weight distribution and the composition distribution are narrow, and the impact strength is excellent. These polymers have different properties from the ethylene / α-olefin copolymers of these (C) components obtained with conventional Ziegler type catalysts and Philips type catalysts (hereinafter collectively referred to as Ziegler type catalysts). .
[0042]
The ethylene polymer (C) component forming the composition used in the present invention has a density of 0.86 obtained by a conventional Ziegler type catalyst or a Phillips type catalyst (hereinafter collectively referred to as a Ziegler type catalyst) by an ionic polymerization method. ~ 0.97g / cm^ThreeEthylene polymer or ethylene / α-olefin copolymer, specifically, high density polyethylene (HDPE), linear medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (VLDPE).
[0043]
High density / linear medium / low density polyethylene (HDPE, MDPE, LLDPE) using the Ziegler-type catalyst has a density of 0.91 to 0.97 g / cm.^Three, Preferably 0.91 to 0.96 g / cm^ThreeThe MFR is selected in the range of 0.05 to 20 g / 10 min, preferably 0.1 to 10 g / 10 min, more preferably 0.3 to 10 g / 5 min. Mw / Mn is not particularly limited, but is generally in the range of 3.0 to 13, preferably 3.5 to 8. The composition distribution is not particularly limited but is generally 1.5 or more, preferably 2.0 or more.
[0044]
The ultra-low density polyethylene (VLDPE) using the Ziegler-type catalyst has a density of 0.86 to 0.91 g / cm.^ThreeLess, preferably 0.88-0.905 g / cm^Three, MFR is selected in the range of 0.01 to 20 g / 10 min, preferably 0.1 to 10 g / 10 min. The very low density polyethylene (VLDPE) exhibits intermediate properties between linear low density polyethylene (LLDPE) and ethylene / α-olefin copolymer rubber (EPR, EPDM), and differential scanning calorimetry (DSC). Is a specific ethylene / α-olefin copolymer having a maximum peak temperature (Tm) of 60 ° C. or higher, preferably 100 ° C. or higher, and a boiling n-hexane insoluble content of 10% by weight or higher, at least titanium and And / or polymerized using a catalyst comprising a solid catalyst component containing vanadium and an organoaluminum compound, and a high crystalline portion represented by linear low density polyethylene and an amorphous portion represented by ethylene / α-olefin copolymer rubber The mechanical properties, heat resistance, etc. that are the features of the former, and rubbery elasticity, low temperature resistance, which are the features of the latter Coexist in a well-balanced, such as 撃性.
[0045]
The α-olefin of the ethylene / α-olefin copolymer by the Ziegler-type catalyst has 3 to 12 carbon atoms, preferably 3 to 10 carbon atoms, specifically, propylene, butene-1, 4-methyl. Examples include pentene-1, hexene-1, octene-1, decene-1, dodecene-1. The content of these α-olefins is preferably selected in the range of 3 to 40 mol%.
[0046]
The composition of the surface layer of the sheet pallet of the present invention is (A) component 0 to 95% by weight, preferably 50% by weight or less, more preferably 30% by weight or less, and (B) component 5 to 100% by weight, preferably 50% by weight. More preferably, it is composed of 70% by weight or more, up to 45% by weight of component (C), preferably 35% by weight or less, more preferably 30% by weight or less. When considering heat resistance and the like, it is preferably composed of two components (A) and (B). However, when considering cold resistance, workability, and economy, the component (C) is selected. It is desirable to add up to 45% by weight.
[0047]
Any known technique can be used as a blending method of the above three components (A), (B), and (C). As a typical example, a normal kneader such as a Henschel mixer, an extruder, or a tumbler is used. It is performed by a method such as dry blending or melt mixing. In the present invention, the components (A), (B) and (C) are mixed at a desired ratio as described above, and then formed into a sheet by a usual method such as a coextrusion molding method (for example, a T-die method) or a calendar method. The
[0048]
The thickness of the main layer 2 of the sheet pallet 1 of the present invention is appropriately selected within the range of 0.3 to 5 mm, preferably 0.5 to 3.5 mm. When the thickness of the main layer of the sheet pallet is less than 0.3 mm, the mechanical strength such as the rigidity of the sheet is inferior, and when the thickness exceeds 5 mm, the characteristics required in the present invention are satisfied. There is a concern that the weight will be increased, which may hinder the automation and handling of cargo handling. The thickness of the surface layers 3 and 4 of the sheet pallet 1 is appropriately selected within the range of 0.07 to 1.0 mm, preferably 0.1 to 0.6 mm. If the thickness of the surface layer is less than 0.07 mm, a desired friction coefficient cannot be obtained, and even if the thickness of the surface layer exceeds 1.0 mm, no further effect of increasing the friction coefficient is obtained. The shape of the sheet pallet of the present invention may be an appropriate shape such as a rectangle, a square, an ellipse, or a circle.
[0049]
The present invention also includes various fillers such as carbon black, calcium carbonate, silica, metal fibers, or antioxidants, flame retardants, colorants, antistatic agents, lubricants, ultraviolet absorbers, in the sheet material during melt mixing. You may mix | blend normal additives, such as a dispersing agent, as needed.
[0050]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited by these.
[0051]
(Examples 1-5)
As the main layer 2 of the sheet pallet 1, a polypropylene block copolymer (ethylene content 11% by weight, MFR 1.5 g / 10 min) which is the same component as the propylene polymer (A) used for the surface layers 3 and 4 of the sheet pallet ) Was used.
Next, as the compositions of the surface layers 3 and 4 of the sheet pallet 1, the following were used as the components A), B) and C).
A) Component: (A) Polypropylene block copolymer (ethylene content 11% by weight, MFR 1.5 g / 10 min)
[0052]
B) Component:
<Polymerization of ethylene / α-olefin copolymer>
Polymerization of ethylene butene-1 copolymer
A stainless steel autoclave with a capacity of 3 L equipped with a stirrer was purged with nitrogen, and 1.5 L of purified toluene was added. Next, 10 g of butene-1 was added, and further mixed with bis (n-butylcyclopentadienyl) zirconium dichloride (0.02 mmol as Zr) methylalumoxane [MAO] (MAO / Zr = 500 [molar ratio]). After adding the solution, the temperature was raised to 80 ° C. Next, ethylene was supplied to perform polymerization while maintaining the pressure constant while continuously polymerizing. The physical properties of the obtained ethylene / butene-1 copolymer were as follows.
MFR: 1.9 g / 10 min
Density: 0.9238 g / cm^Three
Melting point: 116 ° C
Molecular weight distribution (Mw / Mn): 2.1
Composition distribution: 1.03
[0053]
C: Linear low density polyethylene (density = 0.925 g / cm) by Ziegler catalyst^ThreeMFR = 2.0 g / 10 min, Mw / Mn = 4.3, composition distribution = 1.6, trade name: Nisseki Linilex, manufactured by Nippon Petrochemical Co., Ltd.)
[0054]
A three-type three-layer T-die molding apparatus (manufactured by Mitsubishi Heavy Industries, Ltd.) with a die width of 1600 mm was used, and the polypropylene block copolymer (ethylene content 11% by weight, MFR 1.5 g / 10 min) was used as the main layer 2. On both sides, the above components A), B) and C) are dry blended so as to have a predetermined ratio shown in Table 1, and then a sheet having a resin temperature of 235 ° C., a cooling roll temperature of 100 ° C., and a take-up speed of 2 mm / min. Under the molding conditions, a sheet pallet material was manufactured by co-extrusion of a sheet having a thickness of 0.9 mm for the main layer 2, a thickness of 0.3 mm for the surface layers 3 and 4 and a width of 1600 mm. Table 1 shows the composition of the various sheet pallet materials and the coefficient of static friction.
The coefficient of static friction was measured by the inclined plate method (cardboard paper / sheet surface).
[0055]
(Comparative Example 1)
Using the same polypropylene block copolymer (ethylene content 11 wt%, MFR 1.5 g / 10 min) as that used as the main layer 2 of the sheet pallet 1 of Examples 1 to 5, without providing the surface layers 3 and 4 A sheet pallet 1 composed of a single layer having a thickness of 0.9 mm was formed. The obtained sheet pallet was measured for the coefficient of static friction under the same conditions as in Examples 1 to 5 and shown in Table 1.
[0056]
As apparent from Table 1, in the examples of the present invention, the surface layers 3 and 4 of the composition comprising the above components A), B) and C) were added to the main layer 2 of the propylene polymer of the sheet pallet 1. By providing, it turns out that the friction coefficient is improving compared with the comparative example of the sheet pallet which consists of a single layer of a propylene polymer.
[0057]
[Table 1]

[0058]
【The invention's effect】
As described above, the sheet pallet of the present invention is provided by providing a main layer of a propylene polymer with a surface layer using a blended composition of a propylene polymer, a specific ethylene (co) polymer and an ethylene polymer. The coefficient of friction can be improved without impairing the rigidity without applying a roughening treatment such as embossing of the sheet. That is, the rigidity required for the sheet pallet is mainly given to the main layer of the propylene polymer, and only the surface layer is formed of a blended composition of the propylene polymer, a specific ethylene (co) polymer and an ethylene polymer. By doing so, the friction coefficient is improved, and the manufacturing cost is remarkably reduced as compared with a sheet pallet made of a single layer of a propylene polymer of the prior art, a specific ethylene (co) polymer and an ethylene polymer. There is an effect.
[Brief description of the drawings]
FIG. 1 is a perspective view of a sheet pallet according to the present invention.
FIG. 2 is a cross-sectional view of a sheet pallet according to the present invention.
[Explanation of symbols]
1: Sheet pallet, 1a: Tab, 2: Sheet body (main layer), 3, 4: Surface layer.

Claims (2)

Comprising a main layer made of a propylene-based polymer, and a surface layer laminated on one or both surfaces of the main layer,
(A) 0 to 95% by weight of a propylene polymer,
(B) (i) In the presence of a catalyst containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton as an essential component, ethylene or ethylene and α having 3 to 20 carbon atoms -Obtained by (co) polymerizing olefins, (b) Density of 0.86-0.97 g / cm ³ , (C) Melt flow rate of 0.01-50 g / 10 min, (d) Molecular weight distribution The parameter Mw / Mn is in the range of 1.8 to 3.5, and (e) an ethylene (co) polymer 5 to 100% by weight having a composition distribution parameter Cb of 1.2 or less, and (C) an ethylene-based polymer 0 to 45. weight%
A sheet pallet comprising: a composition comprising: (wherein the total amount of components (A), (B) and (C) is 100% by weight). The sheet pallet according to claim 1, wherein the main layer has a thickness of 0.3 to 5.0 mm and the surface layer has a thickness of 0.07 to 1.0 mm.

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