JP3692979B2 - Heat-shrinkable polyester film - Google Patents

Description

【０１１８】
η_sp ：比粘度
ｔ₀：オストワルド粘度計を用いた溶媒の落下時間
ｔ：オスワルド粘度計を用いたフィルム溶液の落下時間
Ｃ：フィルム溶液の濃度。
【０１１９】
尚、実際の測定では、Ｈｕｇｇｉｎｓ式においてｋ＝０．３７５とした下記近似式で極限粘度を算出した。
【０１２０】
【数２】

【０１２１】
η_r：相対粘度
（５）キャスト性
押出し機のＴダイと、表面温度を３０℃に制御したキャスティングロールとの間に、タングステンワイヤー製の電極を配設し、電極とキャスティングロール間に７〜１０ｋＶの電圧を印加する。上記Ｔダイから樹脂を温度２８０℃で溶融押出しし、キャスティングロールで冷却することにより厚さ１８０μｍのフィルムを製造する（キャスティングロール速度：３０ｍ／分）。得られるフィルムの表面に発生したピンナーバブルを目視で観察し、下記基準に従って評価した。
【０１２２】
○：ピンナーバブルの発生なし
△：ピンナーバブルの発生が部分的に認められる
×：ピンナーバブルの発生大
（６）熱収縮率
フイルムを１０ｃｍ×１０ｃｍの正方形に裁断し、８５℃±０．５℃の温水中に、無荷重状態で１０秒間浸漬して熱収縮させた後、２５℃±０．５℃の水中に１０秒浸漬した後、試料の縦および横方向の長さを測定し、下記式に従って求めた値である。
熱収縮率（％）＝１００×（収縮前の長さ−収縮後の長さ）÷（収縮前の長さ）
最も収縮率の大きい方向を最大収縮方向とした。
【０１２３】
（７）厚み分布
フィルムを長さ５０ｃｍ、幅５ｃｍに裁断した（厚み測定用試料）。前記試料を１０枚用意し、各試料について接触式厚み計［「ＫＧ６０／Ａ」；アンリツ（株）製］を用いて長さ方向に厚みを測定し、下記式に基づいて厚み分布を求め、その平均値をフィルムの厚み分布とした。
【０１２４】
厚み分布＝（最大厚み−最小厚み）／平均厚み×１００
（８）最大熱収縮応力値
加熱炉付引張試験機（東洋精機（株）製「テンシロン」）を用い、熱収縮性フィルムから、最大収縮方向の長さ２００ｍｍ、幅２０ｍｍのサンプルを切り出し、予め９０℃に加熱した加熱炉中の送風を止めて、サンプルの両端からそれぞれ５０ｍｍの位置でサンプルをチャックに取り付けてチャック間距離が１００ｍｍとなるようにし、その後速やかに加熱炉の扉を閉め送風を再開し検出される収縮応力を測定し、チャートから求まる最大値を最大熱収縮応力値（ＭＰａ）とした。
【０１２５】
（９）収縮仕上がり性
フィルムを溶剤によって接着してチューブを製造した。なお溶剤接着できなかったものについては、ヒートシールを行ってチューブを製造した。このチューブを裁断して熱収縮性ポリエステル系フィルムラベルを作成した。次いで、容量３００ｍｌのガラス瓶にラベルを装着した後、１６０℃（風速１０ｍ／秒）の熱風式熱収縮トンネルの中を１３秒間通過させて、ラベルを収縮させた。収縮白化と収縮斑の程度を目視で判断し、収縮仕上がり性を５段階で評価した。基準は、５：仕上がり性最良、４：仕上がり性良、３：収縮白化または収縮斑少し有り（２ヶ所以内）、２：収縮白化または収縮斑有り（３〜５ヶ所）、１：収縮白化または収縮斑多い（６ヶ所以上）として、４以上を合格レベル、３以下のものを不良とした。
【０１２６】
（１０）溶剤接着性
フィルムを紙管に巻いた状態で雰囲気温度３０℃±１℃、相対湿度８５±２％に制御した恒温恒湿機内に２５０時間放置した後、取り出して、東洋インキ製造社製の草色、金色、白色のインキで３色印刷した後、センターシールマシンを用いて、１，３−ジオキソラン／アセトン＝８０／２０（質量比）の混合溶剤で溶剤接着してチューブを作り、二つ折り状態で巻き取った。このチューブロールを、温度２３℃±１℃、相対湿度６５％±２％の恒温恒湿機内に２４時間放置後、取り出して、巻き返し、接着性をチェックした。手で容易に剥がれる部分があるものを×、軽い抵抗感をもって手で剥がれるものを△、手で容易に剥がれる部分のないものを○として評価した。○が合格である。
【０１２７】
（１１）フィッシュアイ量
フィルムを裁断して２ｃｍ×２ｃｍのサンプルフィルムを１０個調製した。各サンプルフィルムを光学顕微鏡で観察し、大きさ２０μｍ以上のフィッシュアイの個数をカウントした。１０個のサンプルフィルムについての測定結果を平均し、その平均値を用いて１００ｃｍ³当たりのフィッシュアイの個数を求めた。
【０１２８】
合成例１（ポリエステルの合成）
［エステル化工程］
３つの完全混合槽（第１混合槽、第２混合槽、第３混合槽）を連ねた連続エステル化反応装置を用いる。なお各混合槽は、攪拌装置、分縮器（還流装置）、原料仕込み口及び生成物取り出し口を備えている。
【０１２９】
第１混合槽（第１エステル化反応缶）にテレフタル酸（ＴＰＡ）を供給速度２トン／ｈｒで供給すると共に、エチレングリコール（ＥＧ）を前記ＴＰＡ１モルに対して２モル供給し、さらに三酸化アンチモンを供給した。なお三酸化アンチモンは、そのＳｂ原子の量が、前記テレフタル酸（ＴＰＡ）が収率１００モル％でポリエチレンテレフタレート（ＰＥＴ）に転化したとした時のＰＥＴの質量（以下、理論最終生成物質量と称する）に対して１６０ｐｐｍ（質量基準）となる量を供給した。温度２５５℃、圧力＝常圧、平均滞留時間４時間の条件で、水とエチレングリコールとを留出させながらエステル化した。
【０１３０】
第１混合槽（第１エステル化反応缶）の生成物（酸価＝１７５０ｅｑ／ｔｏｎ）を連続的に第２混合槽（第２エステル化反応缶）に移送した。さらに第２混合槽には、第１混合槽から留去したエチレングリコールと、酢酸マグネシウムのエチレングリコール溶液と、トリメチルホスフェート（ＴＭＰＡ）のエチレングリコール溶液とを下記に示す量で供給した。温度２６０℃、圧力＝常圧、平均滞留時間１．５時間の条件で、水とエチレングリコールとを留出させながら、エステル化をさらに継続した。
【０１３１】
第１混合槽から留去したエチレングリコール：供給量＝理論最終生成物質量に対して８質量％
酢酸マグネシウム：供給量＝Ｍｇ原子の量が、理論最終生成物質量に対して、６５ｐｐｍ（質量基準）となる量
ＴＭＰＡ：供給量＝Ｐ原子の量が、理論最終生成物質量に対して、２０ｐｐｍ（質量基準）となる量
第２混合槽（第２エステル化反応缶）の生成物（酸価＝９５０ｅｑ／ｔｏｎ）を連続的に第３混合槽（第３エステル化反応缶）に移送した。さらに第３混合槽には、ＴＭＰＡのエチレングリコール溶液を、リン原子の量が理論最終生成物質量に対して２０ｐｐｍ（質量基準）となる量供給した［第２混合槽におけるＴＭＰＡの添加量：第３混合槽におけるＴＭＰＡの添加量＝１：１（質量比）］。温度２６０℃、圧力＝常圧、平均滞留時間０．５時間の条件で、水とエチレングリコールとを留出させながら、エステル化をさらに継続した。
【０１３２】
［重合工程］
前記第３混合槽で生成したエステル（酸価＝３００ｅｑ／ｔｏｎ）を３段の連続重合反応装置に連続的に供給して重縮合を行い［第１〜第３重合槽トータルでの重合時間（滞留時間）＝４時間］、ポリエステルを製造し、ストランド状で水中へ吐出した。吐出物をストランドカッターで切断することにより、ポリエステルチップＡを得た（極限粘度：０．７３ｄｌ／ｇ）。
【０１３３】
合成例２
［エステル化工程］
２つの完全混合槽（第１混合槽、第２混合槽）を連ねた連続エステル化反応装置を用いる。なお各混合槽は、攪拌装置、分縮器、原料仕込み口及び生成物取り出し口を備えている。
【０１３４】
第１混合槽（第１エステル化反応缶）にテレフタル酸（ＴＰＡ）を供給速度２トン／ｈｒで供給すると共に、エチレングリコール（ＥＧ）を前記ＴＰＡ１モルに対して２モル供給し、さらに三酸化アンチモン、酢酸マグネシウムのエチレングリコール溶液、及びＴＭＰＡのエチレングリコール溶液を下記に示す量で供給した。温度２５５℃、圧力＝常圧、平均滞留時間４時間の条件で、水とエチレングリコールとを留出させながら、エステル化をした。
【０１３５】
三酸化アンチモン：供給量＝Ｓｂ原子の量が、理論最終生成物質量に対して、１６０ｐｐｍ（質量基準）となる量
酢酸マグネシウム：供給量＝Ｍｇ原子の量が、理論最終生成物質量に対して、６５ｐｐｍ（質量基準）となる量
ＴＭＰＡ：供給量＝Ｐ原子の量が、理論最終生成物質量に対して、２０ｐｐｍ（質量基準）となる量
第１混合槽（第１エステル化反応缶）の生成物（酸価＝１７５０ｅｑ／ｔｏｎ）を連続的に第２混合槽（第２エステル化反応缶）に移送した。さらに第２混合槽には、第１混合槽から留去したエチレングリコールと、ＴＭＰＡのエチレングリコール溶液とを下記に示す量で供給した。温度２６０℃、圧力＝常圧、平均滞留時間１．５時間の条件で、水とエチレングリコールとを留出させながら、エステル化をさらに継続した。
【０１３６】
第１混合槽から留去したエチレングリコール：供給量＝理論最終生成物質量に対して８質量％
ＴＭＰＡ：供給量＝Ｐ原子の量が、理論最終生成物質量に対して、２０ｐｐｍ（質量基準）となる量
［重合工程］
前記第２混合槽で生成したエステルを３段の連続重合反応装置に連続的に供給し、合成例１と同様にして、ポリエステルチップＢを得た（極限粘度：０．７２ｄｌ／ｇ）。
【０１３７】
合成例３
第１混合槽においてＥＧをＴＰＡ１モルに対して２モル供給するのに代えて、ＥＧをＴＰＡ１モルに対して１．３６モル供給し、１，４−シクロヘキサンジメタノール（ＣＨＤＭ）をＴＰＡ１モルに対して０．６４モル供給する以外は、合成例１と同様にしてポリエステルチップＣを得た（極限粘度：０．７８ｄｌ／ｇ）。
【０１３８】
合成例４
第１混合槽においてＥＧをＴＰＡ１モルに対して２モル供給するのに代えて、ＥＧをＴＰＡ１モルに対して１．３６モル供給し、１，４−シクロヘキサンジメタノール（ＣＨＤＭ）をＴＰＡ１モルに対して０．６４モル供給する以外は、合成例２と同様にしてポリエステルチップＤを得た（極限粘度：０．７６ｄｌ／ｇ）。
【０１３９】
合成例５
第１混合槽においてＥＧをＴＰＡ１モルに対して２モル供給するのに代えて、１，４−ブタンジオール（ＢＤ）をＴＰＡ１モルに対して２モル供給する点、第１混合槽において三酸化アンチモンをＳｂ原子の量で理論最終生成物質量に対して１６０ｐｐｍ（質量基準）供給するのに代えて、チタニウムテトラブトキシドをＴｉ原子の量で理論最終生成物質量に対して１５ｐｐｍ（質量基準）供給する点、及び第２混合槽においてＥＧを追加しない点以外は、合成例１と同様にしてポリエステルチップＥを得た（極限粘度：０．９０ｄｌ／ｇ）。
【０１４０】
合成例６
１，４−ブタンジオール（ＢＤ）に代えて、１，３−プロパンジオールを用いる以外は、合成例５と同様にしてポリエステルチップＦを得た（極限粘度：０．８８ｄｌ／ｇ）。
【０１４１】
前記合成例１〜合成例６で得られたポリエステルチップＡ〜Ｆの組成と物性とを表１に示す。
【０１４２】
【表１】

【０１４３】
なお表中、無機成分（Ｍｇ、Ｐ、Ｓｂ、Ｔｉ）の含有量は、各原子の濃度（単位：ｐｐｍ；質量基準）で示す。また各略記号の意味は以下の通りである。
【０１４４】
ＴＰＡ：テレフタル酸
ＥＧ：エチレングリコール
ＣＨＤＭ：１，４−シクロヘキサンジメタノール
ＢＤ：１，４−ブタンジオール
ＰＤ：１，３−プロパンジオール
Ｓｂ₂Ｏ₃：三酸化アンチモン
Ｍｇ（ＯＡｃ）₂：酢酸マグネシウム
Ｔｉ（ＯＢｕ）₄：チタニウムテトラブトキシド
ＴＭＰＡ：トリメチルホスフェート
実施例１
上記合成例で得られた各チップを別個に予備乾燥し、チップＡを３７質量％、チップＣを５３質量％、チップＥを１０質量％の割合で混合し、単軸式押出機を用いて温度２８０℃で溶融押出しし、その後急冷して、厚さ１８０μｍの未延伸フィルムを得た。この未延伸フィルムを９１℃で１０秒間予熱した後、テンターを用いて温度７２℃で横方向に４．０倍延伸し、続いて温度７９℃で１０秒間熱処理を行って、厚さ４５μｍの熱収縮性ポリエステル系フィルムを得た。得られたフィルム中のジカルボン酸成分及び多価アルコール成分の組成と物性値を表２に示す。
【０１４５】
実施例２
上記合成例で得られた各チップを別個に予備乾燥し、チップＡを５質量％、チップＣを７０質量％、チップＥを２５質量％の割合で混合し、単軸式押出機を用いて温度２８０℃で溶融押出しし、その後急冷して、厚さ１８０μｍの未延伸フィルムを得た。この未延伸フィルムを温度７８℃で１０秒間予熱した後、テンターを用いて温度７３℃で横方向に４．０倍延伸し、続いて温度８０℃で１０秒間熱処理を行って、厚さ４５μｍの熱収縮性ポリエステル系フィルムを得た。得られたフィルム中のジカルボン酸成分及び多価アルコール成分の組成と物性値を表２に示す。
【０１４６】
比較例１
上記合成例で得られた各チップを別個に予備乾燥し、チップＢを３７質量％、チップＤを５３質量％、チップＥを１０質量％の割合で混合し、単軸式押出機を用いて温度２８０℃で溶融押出しし、その後急冷して、厚さ１８０μｍの未延伸フィルムを得た。この未延伸フィルムを温度９１℃で１０秒間予熱した後、テンターを用いて温度７２℃で横方向に４．０倍延伸し、続いて温度７９℃で１０秒間熱処理を行って、厚さ４５μｍの熱収縮性ポリエステル系フィルムを得た。得られたフィルム中のジカルボン酸成分及び多価アルコール成分の組成と物性値を表２に示す。
【０１４７】
比較例２
上記合成例で得られた各チップを別個に予備乾燥し、チップＢを５質量％、チップＤを７０質量％、チップＥを２５質量％の割合で混合し、単軸式押出機を用いて温度２８０℃で溶融押出しし、その後急冷して、厚さ１８０μｍの未延伸フィルムを得た。この未延伸フィルムを温度７８℃で１０秒間予熱した後、テンターを用いて温度７３℃で横方向に４．０倍延伸し、続いて温度８０℃で１０秒間熱処理を行って、厚さ４５μｍの熱収縮性ポリエステル系フィルムを得た。得られたフィルム中のジカルボン酸成分及び多価アルコール成分の組成と物性値を表２に示す。
【０１４８】
比較例３
上記合成例で得られた各チップを別個に予備乾燥し、チップＡを６４質量％、チップＣを１０質量％、チップＥを２６質量％の割合で混合し、単軸式押出機を用いて温度２８０℃で溶融押出しし、その後急冷して、厚さ１８０μｍの未延伸フィルムを得た。この未延伸フィルムを温度１０５℃で１０秒間予熱した後、テンターを用いて温度７３℃で横方向に４．０倍延伸し、続いて温度７６℃で１０秒間熱処理を行って、厚さ４５μｍの熱収縮性ポリエステル系フィルムを得た。得られたフィルム中のジカルボン酸成分及び多価アルコール成分の組成と物性値を表２に示す。
【０１４９】
実施例３
上記合成例で得られた各チップを別個に予備乾燥し、チップＡを３４質量％、チップＣを５３質量％、チップＦを１３質量％の割合で混合し、単軸式押出機を用いて温度２８０℃で溶融押出しし、その後急冷して、厚さ１８０μｍの未延伸フィルムを得た。この未延伸フィルムを９１℃で１０秒間予熱した後、テンターを用いて温度７２℃で横方向に４．０倍延伸し、続いて温度７９℃で１０秒間熱処理を行って、厚さ４５μｍの熱収縮性ポリエステル系フィルムを得た。得られたフィルム中のジカルボン酸成分及び多価アルコール成分の組成と物性値を表２に示す。
【０１５０】
【表２】

【０１５１】
なお表中、無機成分（Ｍｇ、Ｐ、Ｓｂ、Ｔｉ）の含有量は、各原子の濃度（単位：ｐｐｍ；質量基準）で示す。また各略記号の意味は以下の通りである。
【０１５２】
ＴＰＡ：テレフタル酸
ＥＧ：エチレングリコール
ＣＨＤＭ：１，４−シクロヘキサンジメタノール
ＢＤ：１，４−ブタンジオール
ＰＤ：１，３−プロパンジオール
ＤＥＧ：ジエチレングリコール
【０１５３】
【発明の効果】
本発明の熱収縮性ポリエステル系フィルムは、１，４−シクロヘキサンジメタノール成分を所定量含有しているため、低温での収縮性がよく、かつ収縮仕上がり性に優れており、さらには所定の製造方法によって製造されているため、不溶性異物の量が少なく、美麗な外観を得ることができる。そのため収縮ラベル、キャップシール、収縮包装等の用途に好適に用いることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-shrinkable polyester film, and more particularly to a heat-shrinkable polyester film suitable for label applications.
[0002]
[Prior art]
Heat-shrinkable plastic films are widely used for applications such as shrink wrapping, shrinkage labels, cap seals, etc. by utilizing the property of shrinking by heating. Among them, stretched films such as polyvinyl chloride films, polystyrene films, and polyester films are used for labels, cap seals, and integrated packaging in various containers such as polyethylene terephthalate (PET) containers, polyethylene containers, and glass containers. It is used.
[0003]
However, the polyvinyl chloride film has problems such as low heat resistance, generation of hydrogen chloride gas during incineration, and dioxin. Further, when a heat-shrinkable vinyl chloride resin film is used as a shrink label for a PET container or the like, there is a problem that the label and the container must be separated when the container is recycled.
[0004]
On the other hand, a polystyrene film can be evaluated for its good finished appearance after shrinkage, but it is poor in solvent resistance, so an ink with a special composition must be used for printing. In addition, the polystyrene film needs to be incinerated at a high temperature and has a problem that a large amount of black smoke and off-flavor are generated at the time of incineration.
[0005]
Polyester films without these problems are highly expected as shrink labels to replace polyvinyl chloride films and polystyrene films, and the amount of use tends to increase as the amount of PET container used increases.
[0006]
However, the conventional heat-shrinkable polyester film has also been required to have further improvement in shrinkage characteristics. In particular, shrinkage spots and wrinkles occur during shrinkage, and characters and designs printed on the film before shrinkage may be distorted after being covered and shrunk on containers such as PET bottles, polyethylene bottles, and glass bottles. There was a user's request to make it as small as possible. Moreover, the shrinkage stress was small, and the adhesion of the film to the container was inferior.
[0007]
Furthermore, compared with heat-shrinkable polystyrene film, polyester film may be inferior in shrinkability at low temperature, and must be shrunk at high temperature to obtain the required shrinkage, Whitening sometimes occurred.
[0008]
By the way, when using a heat-shrinkable film for the covering process of an actual container, after using for a printing process as needed, it processes into forms, such as a label (tubular label), a tube, and a bag. These processed films are attached to a container, and then the belt is placed inside a shrink tunnel (steam tunnel) in which steam is blown and thermally contracted, or in a shrink tunnel (hot air tunnel) in which hot air is blown and shrunk. It is placed on a conveyor and passed through, and is heat-shrinked so as to be in close contact with the container.
[0009]
Steam tunnels have better heat transfer efficiency than hot air tunnels and can be heated and shrunk more uniformly, and can have a better shrink-finished appearance than hot air tunnels, but conventional heat-shrinkable polyester films Has a problem that the shrinkage finish after passing through the steam tunnel is not so good as compared with the polyvinyl chloride film and the polystyrene film.
[0010]
In addition, when a hot air tunnel that easily generates temperature spots during heat shrinkage is used, shrinkage whitening, shrinkage spots, wrinkles, distortion, and the like are likely to occur in the polyester film. In particular, shrinkage whitening has been a problem in terms of product appearance. The polyester film is inferior to the polyvinyl chloride film or the polystyrene film in terms of shrink finish after passing through the hot air tunnel.
[0011]
Further, the heat-shrinkable film is required to increase productivity in addition to the shrinkage finish, and further, it is required to have high transparency from the viewpoint of quality. In order to increase productivity, it is conceivable that when a melt-extruded film is cooled by a casting roll, the film and the roll are electrostatically brought into close contact with each other to increase the cooling efficiency and increase the casting speed. If the film is electrostatically adhered to the roll, defects on the film surface (such as occurrence of pinner bubbles) can be reduced, and further, the thickness of the film can be made uniform. In order to bring the film into electrostatic contact with the roll, it is important how many charge carriers are present on the surface of the molten film immediately after extrusion before contacting the roll. In order to increase the number of charge carriers, it is effective to modify the polyester to lower its specific resistance, and great efforts have been made. For example, in Japanese Examined Patent Publication No. 3-54129, a magnesium compound, a sodium or potassium compound, and a phosphorus compound are added during the production of polyethylene terephthalate (PET), and the Mg atom concentration is 30 to 400 ppm, and the Na atom or K atom concentration. It is disclosed that the specific resistance value of the PET film is lowered by setting the atomic ratio of Mg to P to 1.2 to 20 and the atomic ratio of Mg to P to 1.2 to 20 ppm. In this publication, a magnesium compound is further added when the esterification rate is 20 to 80%, and a sodium or potassium compound is added until the intrinsic viscosity reaches 0.2, and the esterification rate proceeds by 90% or more. The formation of insoluble foreign matter is suppressed by adding a phosphorus compound from the time when the intrinsic viscosity reaches 0.2, thereby improving the quality of the film. In this publication, although antimony trioxide is also used as a catalyst, there is no description on how to make the relationship between the antimony trioxide addition time and the magnesium compound addition time. In the column of Examples, antimony trioxide is added to the first esterification reaction can of the continuous esterification apparatus composed of the first esterification reaction can and the second esterification reaction can, and magnesium acetate is also added at the same time.
[0012]
On the other hand, as disclosed in JP-T-2000-504770, polyester obtained by copolymerization of 1,4-cyclohexanedimethanol (CHDM) is attracting attention because of its excellent transparency and brightness. However, since this copolymerizable polyester has a high specific resistance value, modification to improve electrostatic adhesion is necessary from the viewpoint of improving the productivity and quality of the film.
[0013]
[Problems to be solved by the invention]
Therefore, in the polyester copolymerized with CHDM, it is conceivable to apply the method developed in the PET (Japanese Patent Publication No. 3-54129). However, since the raw materials and properties of the polymer are different, its effectiveness is I doubt it. That is, polyester copolymerized with CHDM has greatly different thermal properties (melting point, crystallization temperature, glass transition temperature, etc.) and lower heat resistance than PET. Therefore, in the polyester copolymerized with CHDM, if an additive is added to lower the melt specific resistance value, the thermal properties are greatly changed, the heat resistance is further lowered, the polyester is colored, the viscosity is lowered (the molecular weight is lowered). ) Is more likely to occur.
[0014]
In addition, the heat-shrinkable polyester film is required to reduce foreign matters in the film and reduce defects such as fish eyes in order to enhance the designability (aesthetic appearance). Therefore, the polyester used as the raw material of the film requires a high degree of clarity, and measures are taken to increase the clarity. As one of the methods, a method of increasing the clarity by generally filtering the polyester using a fine filter is adopted. However, the filtration with a filter is insufficient in suppressing fish eyes, and further clarification is required.
[0015]
The present invention has been made paying attention to the circumstances as described above, and its purpose is to have excellent shrinkage characteristics at low temperature without reducing heat resistance, excellent shrinkage finish, and aesthetics. It is in the point which provides the heat-shrinkable polyester-type film suitable for the outstanding label use.
[0016]
[Means for Solving the Problems]
The heat-shrinkable polyester film of the present invention has a 1,4-cyclohexanedimethanol component of 5 mol% or more out of 100 mol% of a polyhydric alcohol component, an alkaline earth metal compound, a phosphorus compound, and a polymerization catalyst. Containing a metal-containing compound for polymerization (such as a titanium compound, a manganese compound, a cobalt compound, a germanium compound, a tin compound, and an antimony compound) derived from the above, and having the following characteristics (1) and (2) It is.
[0017]
(1) When a sample of a heat-shrinkable polyester film cut into a 10 cm × 10 cm square shape is dipped in hot water at 85 ° C. for 10 seconds and then dipped in water at 25 ° C. for 10 seconds Thermal shrinkage in the maximum shrinkage direction is 20% or more
(2) The amount of insoluble foreign matter having a particle size of 0.1 μm or more contained in 1 kg of film is determined by the amount of alkaline earth metal atom M in the foreign matter.¹And metal atom for polymerization M^xThe total amount is 1 mg or less
Alkaline earth metal atom M in the film², Phosphorus atom, and metal atom for polymerization M^xThe content of is usually 40 ppm (mass basis) or more, 20 ppm (mass basis) or more, and 50 ppm (mass basis) or more, respectively. Such a film has not only excellent shrinkage finish properties in a wide temperature range from low temperature to high temperature, but also a compound that easily generates insoluble foreign matter [an alkaline earth metal compound, a phosphorus compound, a metal-containing compound for polymerization ( In particular, the amount of insoluble foreign matter is small in spite of containing an antimony compound, etc.], so that the aesthetics of the film are extremely excellent.
[0018]
The film has a specific resistance value of 0.70 × 10 at a temperature of 275 ° C.⁸It is desirable that it is Ω · cm or less. In such a film, the alkaline earth metal atom M in the film²And the atomic weight ratio of phosphorus atom P (M²/ P) is, for example, about 1.2 to 5.0. When the melt specific resistance value is small, when extruding the film, electrostatic adhesion to the casting roll of the film can be increased, productivity can be increased, and pinner bubbles can be reduced to improve the aesthetics of the film. It can be further increased.
[0019]
As for the said film, it is desirable for the ratio of 1, 4- cyclohexane dimethanol in 100 mol% of polyhydric alcohol components to be 10-80 mol%. Such a film can remarkably reduce shrinkage whitening and shrinkage spots, and can further enhance the aesthetics of the film.
[0020]
The film preferably has an intrinsic viscosity of 0.66 dl / g or more. Such a film not only has excellent tear resistance and excellent workability, but also has excellent shrinkage stress persistence and can further reduce shrinkage whitening and shrinkage spots.
[0021]
When the thickness of the film relative to the maximum shrinkage direction of the film is measured using a test piece having a length in the maximum shrinkage direction of 50 cm and a width of 5 cm, the thickness distribution represented by the following formula is 7% or less. It is desirable that
[0022]
Thickness distribution = (maximum thickness−minimum thickness) / average thickness × 100
When the thickness distribution is controlled within the above range, when multicolor printing is performed on a film, the processability is excellent, and furthermore, color misregistration can be highly prevented.
[0023]
When the film is subjected to a heat shrink test in the direction of maximum shrinkage of the film in hot air at 90 ° C. under conditions of a test piece width of 20 mm and a distance between chucks of 100 mm, the maximum heat shrinkage stress value is usually 3 MPa or more. It is.
[0024]
The film can be obtained by using a low foreign substance polyester produced by a predetermined production method described below. In the low foreign substance polyester, the esterification process is divided into three or more steps having different degrees of progress of esterification and oligomerization, and an alkaline earth metal compound is added after the second step, and an alkaline earth metal compound is added. In the steps after the step, it can be produced by adding a phosphorus compound in a plurality of steps and polymerizing the resulting ester and oligomer.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
The heat-shrinkable polyester film of the present invention is obtained when a sample cut into a 10 cm × 10 cm square shape is dipped in hot water at 85 ° C. for 10 seconds and immediately dipped in water at 25 ° C. for 10 seconds. The heat shrinkage rate in the maximum shrinkage direction is 20% or more. When the film has a heat shrinkage rate of less than 20%, the amount of heat shrinkage of the film is insufficient when the container is coated and shrunk, resulting in poor appearance. A more preferable heat shrinkage rate is 30% or more, and further preferably 40% or more. The upper limit of the heat shrinkage rate is preferably 80% (particularly 75%).
[0026]
Here, the heat shrinkage rate in the maximum shrinkage direction means the heat shrinkage rate in the direction in which the sample has shrunk most, and the maximum shrinkage direction is the length of the square in the vertical direction or in the horizontal direction (or oblique direction). It is decided by. Further, the heat shrinkage rate (%) was 25 ° C. ± 0.5 after a sample of 10 cm × 10 cm was immersed in warm water at 85 ° C. ± 0.5 ° C. for 10 seconds under a no-load condition and then heat shrunk. Measure the length of the film in the vertical and horizontal directions (or diagonal directions) after 10 seconds of immersion in water at 0 ° C. under no load condition.
Heat shrinkage rate = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage)
The value obtained according to
[0027]
The heat shrinkable polyester film preferably has a higher heat shrinkage stress value (maximum heat shrinkage stress value) in the maximum shrinkage direction. When the heat shrinkage stress value is high, the film (label or the like) can be prevented from loosening after the container is coated, and deterioration of tear resistance due to insufficient mechanical strength of the film can be prevented. The maximum heat shrinkage stress value of the heat-shrinkable polyester film of the present invention is usually 3 MPa or more when a heat shrink test is performed in hot air at 90 ° C. under the conditions of a test piece width of 20 mm and a distance between chucks of 100 mm. Is 3.5 MPa or more, more preferably 4 MPa or more.
[0028]
The maximum heat shrinkage stress value is measured as follows.
[0029]
(1) A test piece having a length in the maximum shrinkage direction of 200 mm and a width of 20 mm is cut out from the heat-shrinkable film.
[0030]
(2) The inside of a heating furnace of a tensile testing machine (for example, “Tensilon” manufactured by Toyo Seiki Co., Ltd.) equipped with a hot air type heating furnace is heated to 90 ° C.
[0031]
(3) Stop blowing and set the test piece in the heating furnace. The distance between chucks is 100 mm (constant).
[0032]
(4) Close the heating furnace door quickly, resume air blowing, and detect and measure heat shrinkage stress.
[0033]
(5) The maximum value is read from the chart, and this is taken as the maximum heat shrinkage stress value (MPa).
[0034]
In order to achieve the predetermined heat shrinkage rate, it is effective to adjust the composition of the polyester film. Further, the maximum heat shrinkage stress value can be controlled within the predetermined range by adjusting the composition of the polyester film. That is, although details will be described later, in the heat-shrinkable polyester film of the present invention, it is desirable to use a crystalline unit (such as an ethylene terephthalate unit) as a polyester base component. Since the crystalline unit has a role of increasing the crystallinity of the polyester film, it can exhibit the tear resistance, strength, heat resistance, and the like of the film. However, only the crystalline unit has low heat shrinkability. Therefore, in the present invention, the composition of the polyester-based film is adjusted to increase the degree of amorphousness and to improve the heat shrinkability.
[0035]
More specifically, the heat-shrinkable polyester film of the present invention is a film obtained by using one or a plurality of polyesters, and contains a dicarboxylic acid component and a polyhydric alcohol component constituting the polyester. And the polyhydric alcohol component is prepared so that 5 mol% or more of 1, 4- cyclohexane dimethanol components may be contained with respect to the whole polyhydric alcohol component (100 mol%). When the proportion of the 1,4-cyclohexanedimethanol component is 5 mol% or more, the degree of amorphousness of the film can be increased, and a predetermined heat shrinkage rate can be achieved. It is also possible to achieve a predetermined maximum heat shrinkage stress value. Furthermore, shrinkage finish (suppression of shrinkage whitening, suppression of contraction spots, suppression of wrinkles, suppression of distortion, and / or suppression of vertical shrinkage, etc.) can also be improved. The heat-shrinkable film is often processed into a label (tubular label), a tube, a bag, or the like by bonding with a solvent (such as tetrahydrofuran or 1,3-dioxolane). -When the ratio of a cyclohexane dimethanol component is 5 mol% or more, solvent adhesiveness can also be normally improved.
[0036]
By the way, in the conventional heat-shrinkable polyester film, when the temperature reaches the temperature at which the film is heated in the heat-shrinking process, the heat shrinkage rate is saturated depending on the composition of the polyester constituting the film, and the temperature is higher than that. In some cases, no further shrinkage can be obtained. Such a film has an advantage that it can be thermally shrunk at a relatively low temperature. However, when it is heat shrunk in the hot air tunnel or after being stored for a long time in an atmosphere of 30 ° C. or higher before heat shrinking, When contracted, the contraction whitening phenomenon tends to occur. This shrinkage whitening phenomenon is thought to occur because the molecular chain of the polyester is partially crystallized and the refractive index of light in the crystal part is different from that of the amorphous part.
[0037]
However, the present inventors have found that the shrinkage whitening can be remarkably suppressed by setting the ratio of the 1,4-cyclohexanedimethanol component to 10 mol% or more in 100 mol% of the polyhydric alcohol component. Furthermore, shrinkage spots can be remarkably suppressed. The amount of the 1,4-cyclohexanedimethanol component is more preferably 12 mol% or more, and further preferably 14 mol% or more.
[0038]
On the other hand, it is desired to suppress the 1,4-cyclohexanedimethanol component to 80 mol% or less in 100 mol% of the polyhydric alcohol component. If there is too much 1,4-cyclohexanedimethanol component, the shrinkage rate of the film becomes excessively high, and there is a risk that label displacement and pattern distortion may occur in the heat shrinking process. Further, since the solvent resistance of the film is lowered, the film is whitened by an ink solvent (such as ethyl acetate) in the printing process, or the tear resistance of the film is lowered. Accordingly, the 1,4-cyclohexanedimethanol component is more preferably at most 70 mol%, further preferably at most 60 mol%.
[0039]
The film of the present invention may contain a polyhydric alcohol component other than the 1,4-cyclohexanedimethanol component. The polyhydric alcohol component may be a diol component or a trihydric or higher alcohol component. Diols forming the diol component include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl- Alkylene glycols such as 1,5-pentanediol, 2-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol; diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polyoxy Ether glycols such as alkylene oxide adducts of tetramethylene glycol, bisphenol compounds or derivatives thereof; dimer diols and the like are included. Trivalent or higher alcohols include trimethylolpropane, glycerin, pentaerythritol and the like.
[0040]
As the dicarboxylic acids forming the dicarboxylic acid component, aromatic dicarboxylic acids, ester-forming derivatives thereof, aliphatic dicarboxylic acids and the like can be used. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, 5-sodium sulfoisophthalic acid, and the like. Examples of ester derivatives include derivatives such as dialkyl esters and diaryl esters. Examples of the aliphatic dicarboxylic acid include dimer acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, and succinic acid.
[0041]
In addition to the dicarboxylic acids, oxycarboxylic acids such as p-oxybenzoic acid, and trivalent or higher carboxylic acids such as trimellitic anhydride and pyromellitic anhydride may be used in combination as necessary.
[0042]
Polyesters are not necessarily produced from the dicarboxylic acids and polyhydric alcohols, and may be produced by ring-opening polymerization of lactones (such as ε-caprolactone). When calculating the ratio (mol%) of each component in the dicarboxylic acid component and the polyhydric alcohol component, the ring opening component of the lactone is calculated as corresponding to both the dicarboxylic acid component and the polyhydric alcohol component. .
[0043]
Considering the tear resistance, strength, heat resistance, etc. of the film, it is preferable to select the polyester so that the crystalline unit (ethylene terephthalate unit, etc.) in the polyester is 20 mol% or more. Accordingly, the terephthalic acid component is preferably 20 mol% or more in 100 mol% of the polycarboxylic acid component. The ethylene glycol component is preferably 20 mol% or more in 100 mol% of the polyhydric alcohol component. The crystalline unit is more preferably 30 mol% or more, and still more preferably 40 mol% or more. However, in this invention, since 1, 4- cyclohexane dimethanol component is 5 mol% or more in 100 mol% of polyhydric alcohol components, an ethylene glycol component is 95 mol% or less.
[0044]
The film of the present invention contains an alkaline earth metal compound, a phosphorus compound, a metal-containing compound for polymerization, and the like. Alkaline earth metal compounds and phosphorus compounds are sometimes used to reduce the melt resistivity value of the film. Moreover, it may be used for other purposes. For example, a phosphorus compound may be used to increase the heat resistance of a film. On the other hand, a metal-containing compound for polymerization (such as an antimony compound) is often used as a polymerization catalyst when synthesizing a polyester that is a raw material of a film. The present inventors have found that the alkaline earth metal compound, the phosphorus compound, and the metal-containing compound for polymerization (such as an antimony compound) generate insoluble foreign matter, lower the clarity of the film, and cause fish eyes. I found out. That is, the polymerization metal (such as metal antimony) becomes an insoluble foreign substance (coarse particles) in the polyester, and the alkaline earth metal compound reacts with the dicarboxylic acid that is the raw material for producing the polyester to form an insoluble foreign substance (coarse particles). It was determined that the alkaline earth metal compound and the phosphorus compound react to form an insoluble foreign matter (coarse particles). Then, as described later, the present inventors have found that the amount of insoluble foreign matter can be reduced by producing polyester by a predetermined method and forming it into a film.
[0045]
That is, the film of the present invention is not only excellent in the above-mentioned shrinkage characteristics and shrinkage finishing properties, but also insoluble even if it contains a compound that easily generates insoluble foreign matters such as an alkaline earth metal compound, a metal-containing compound for polymerization, and a phosphorus compound. There is very little foreign matter. Therefore, the clarity of a film can be improved and the aesthetics (designability) of a film can be improved by preventing a fish eye.
[0046]
The amount of the insoluble foreign matter is an alkaline earth metal atom M contained in the insoluble foreign matter having a particle size of 0.1 μm or more in 1 kg of the film.²Mass and metal atom for polymerization M^xIt can be evaluated as the mass of (antimony atom Sb or the like). Alkaline earth metal atom M²And metal atom for polymerization M^xThe mass of (antimony atom Sb etc.) can be measured as follows.
[0047]
100 g of a film is dissolved in a mixed solution of p-chlorophenol and tetrachloroethane [volume 5 L; p-chlorophenol / tetrachloroethane = 75/25 (mass ratio)]. This solution is filtered through a membrane filter (average pore size 0.1 μm) made of hydrophilic polytetrafluoroethylene, and the filter is dried. After measuring the mass of the insoluble foreign matter collected on the filter, the alkaline earth metal atom M in the insoluble foreign matter is measured.²And metal atom for polymerization M^xThe concentration of (antimony atom Sb or the like) is measured using fluorescent X-rays (calibration curve method). The mass of the insoluble foreign matter and the alkaline earth metal atom M in the insoluble foreign matter²Concentration and polymerization metal atom M^xBased on the concentration, alkaline earth metal atom M contained in insoluble foreign matter in 1 kg of film²Mass (mg) and metal atom for polymerization M^xThe mass (mg) of (antimony atom Sb, etc.) is calculated.
[0048]
In the film of the present invention, the alkaline earth metal atom M contained in the insoluble foreign matter having a particle size of 0.1 μm or more.²And metal atom for polymerization M^xIs 1 mg or less (preferably 0.9 mg or less, more preferably 0.7 mg or less) per 1 kg of film.
[0049]
When lowering the melt resistivity value using an alkaline earth metal compound and a phosphorus compound, the alkaline earth metal atom M in the film²Ratio of atomic weight to phosphorus atom P (M²/ P) is desirably 1.2 or more (preferably 1.3 or more, more preferably 1.4 or more). Atomic ratio (M²By setting / P) to 1.2 or more, the melting specific resistance can be remarkably reduced. In addition, atomic weight ratio (M²When / P) exceeds 5.0, the amount of insoluble foreign matter produced tends to increase even if polyester is produced by a predetermined method described later. Therefore, atomic weight ratio (M²/ P) is 5.0 or less, preferably 4.9 or less, more preferably 4.8 or less.
[0050]
When the ratio of the alkaline earth metal compound and the phosphorus compound is controlled within the above range, the melt specific resistance value of the film is, for example, 0.70 × 10⁸Ω · cm or less. When the melt specific resistance value is small, when the film melt-extruded from the extruder is cooled by a casting roll, the electrostatic adhesion of the film to the roll can be enhanced. Therefore, the stability of cooling and solidification can be increased, and the casting speed (production speed) can be increased. The melt specific resistance is preferably 0.65 × 10⁸Ω · cm or less, more preferably 0.60 × 10⁸Ω · cm or less.
[0051]
In addition to the alkaline earth metal compound and the phosphorus compound, when an alkali metal compound is contained in the film, the melting specific resistance value of the film can be further lowered.
[0052]
When the melting specific resistance value is lowered, not only the electrostatic adhesion can be enhanced, but also the film quality can be enhanced. That is, when the electrostatic adhesion is low, the film solidification may be incomplete and pinner bubbles may occur on the film surface, whereas the electrostatic adhesion can reduce the pinner bubbles, The film appearance can be enhanced.
[0053]
In addition, when the electrostatic adhesion is improved, the thickness of the film can be made uniform. In other words, if the electrostatic adhesion to the casting roll is low, the thickness of the cast unstretched film raw material becomes non-uniform, and the nonuniform thickness of the stretched film obtained by stretching the unstretched film is further expanded. On the other hand, when the electrostatic adhesion is sufficiently high, the thickness of the stretched film can be made uniform.
[0054]
The thickness uniformity can be evaluated by the thickness distribution represented by the following formula.
[0055]
Thickness distribution = (maximum thickness−minimum thickness) / average thickness × 100
The maximum thickness, the minimum thickness, and the average thickness are obtained by cutting a test piece from the film so that the length in the maximum shrinkage direction is 50 cm and the width is 5 cm, and the thickness is displaced with respect to the maximum shrinkage direction using a contact-type thickness meter. Can be determined by measuring.
[0056]
The thickness distribution is, for example, 7% or less, preferably 6% or less, and more preferably 5% or less. If the thickness distribution is too large when multicolor printing is performed on the film, wrinkles are likely to occur in the film, and meandering is likely to occur during film running, so that workability is reduced and color misregistration occurs. Further, when the film is processed into a tube or the like by solvent bonding, it is difficult to overlap the bonded portions. In addition, when the film is wound in a roll shape, a difference in partial winding hardness may occur, and the film may be loosened or wrinkled, greatly deteriorating the appearance of the film.
[0057]
In order to sufficiently reduce the thickness distribution, it is desirable to optimize stretching conditions such as the film stretching ratio, preheating temperature during stretching, and stretching temperature, in addition to improving electrostatic adhesion.
[0058]
In the present invention, a polyester is produced by a predetermined method, and the amount of insoluble foreign matter produced is reduced by forming the polyester into a film. Therefore, compounds that cause insoluble foreign matter (alkaline earth metal compound, phosphorus compound, polymerization) This is effective when the metal-containing compound) is contained in a predetermined amount or more. The content of the alkaline earth metal compound in the film is alkaline earth metal atom M²For example, 40 ppm (mass basis) or more [preferably 45 ppm (mass basis) or more, more preferably 50 ppm (mass basis) or more], and the phosphorus compound content in the film is based on the phosphorus atom P. For example, it is 20 ppm (mass basis) or more [preferably 25 ppm (mass basis) or more, more preferably 30 ppm (mass basis) or more], and the content of the metal-containing compound for polymerization (such as antimony compound) in the film is polymerized. Metal atom M^xBased on (antimony atom Sb and the like), for example, 50 ppm (mass basis) or more [in many cases 80 ppm (mass basis) or more, more often 100 ppm (mass basis) or more]. When the amount of the alkaline earth metal compound or the phosphorus compound is not less than the predetermined amount, the melt specific resistance value of the film can be lowered.
[0059]
The upper limit of the amount of the alkaline earth metal compound, the phosphorus compound, and the metal-containing compound for polymerization is not particularly limited. However, the smaller the amount of each compound, the easier it is to reduce the amount of insoluble foreign matter. The content of the alkaline earth metal compound in the film is determined by the alkaline earth metal atom M.²For example, 100 ppm (mass basis) or less [preferably 70 ppm (mass basis) or less, more preferably 65 ppm (mass basis) or less]. The phosphorus compound content in the film may be, for example, 55 ppm (mass basis) or less [preferably 45 ppm (mass basis) or less, more preferably 40 ppm (mass basis) or less] based on the phosphorus atom P. The content of the metal-containing compound for polymerization (antimony compound, etc.) in the film is determined by the metal atom M for polymerization.^xBased on (antimony atom Sb and the like), for example, it is 200 ppm (mass basis) or less [preferably 175 ppm (mass basis) or less, more preferably 150 ppm (mass basis) or less].
[0060]
On the other hand, it is preferable that the amount of the alkali metal compound is large when the melting resistivity value is lowered. The content of the alkali metal compound in the film is the alkali metal atom M.¹For example, 5 ppm (mass basis) or more, preferably 6 ppm (mass basis) or more, more preferably 7 ppm (mass basis) or more. Even if the content of the alkali metal compound is excessively increased, the effect of reducing the melt specific resistance value is saturated. The content of the alkali metal compound is the alkali metal atom M.¹For example, 100 ppm (mass basis) or less, preferably 90 ppm (mass basis) or less, more preferably 80 ppm (mass basis) or less.
[0061]
Examples of the alkaline earth metal compound include an alkaline earth metal hydroxide, alkoxide, aliphatic carboxylate (acetate, butyrate, etc., preferably acetate), aromatic carboxylate (benzoate), And salts with a compound having a phenolic hydroxyl group (such as a salt with phenol). Examples of the alkaline earth metal include magnesium, calcium, strontium, barium and the like (preferably magnesium). Preferred alkaline earth metal compounds include magnesium hydroxide, magnesium methoxide, magnesium acetate, calcium acetate, strontium acetate, barium acetate and the like, especially magnesium acetate. The alkaline earth metal compounds can be used alone or in combination of two or more.
[0062]
Examples of the phosphorus compound include phosphoric acids (phosphoric acid, phosphorous acid, hypophosphorous acid, etc.), and esters thereof (alkyl esters, aryl esters, etc.), as well as alkylphosphonic acids, arylphosphonic acids, and esters thereof (alkyl esters). And aryl esters). Preferred phosphorus compounds include phosphoric acid, aliphatic esters of phosphoric acid (alkyl esters of phosphoric acid, etc .; for example, phosphoric acid monomethyl esters, phosphoric acid monoethyl esters, phosphoric acid monobutyl esters, etc._1-6Dialkyl phosphates such as alkyl esters, dimethyl phosphate, diethyl phosphate, and dibutyl phosphate_1-6Triphosphate C such as alkyl ester, trimethyl phosphate, triethyl phosphate, tributyl phosphate_1-6Alkyl esters, etc.), aromatic esters of phosphoric acid (triphenyl phosphate, tricresyl phosphate, mono-, di-, or tri-C_6-9Aryl esters, etc.), aliphatic esters of phosphorous acid (alkyl esters of phosphorous acid, etc.); for example, trimethyl phosphite, tributyl phosphite, mono-, di- or tri-C of phosphorous acid_1-6Alkyl esters, etc.), alkylphosphonic acids (methylphosphonic acid, ethylphosphonic acid, etc.)_1-6Alkylphosphonic acid), alkylphosphonic acid alkylesters (dimethylphosphonic acid dimethyl, ethylphosphonic acid dimethyl C, etc._1-6Mono- or di-C of alkylphosphonic acid_1-6Alkyl esters), arylphosphonic acid alkyl esters (dimethyl phenylphosphonate, diethyl phenylphosphonate, etc.)_6-9Mono- or di-C of arylphosphonic acid_1-6Alkyl esters), arylphosphonic acid aryl esters (phenylphosphonic acid diphenyl, etc.)_6-9Mono- or di-C of arylphosphonic acid_6-9An aryl ester etc.) etc. can be illustrated. Particularly preferred phosphorus compounds include phosphoric acid and trialkyl phosphate (such as trimethyl phosphate). These phosphorus compounds can be used alone or in combination of two or more.
[0063]
Examples of the metal-containing compound for polymerization include titanium compounds (such as titanium tetrabutoxide), manganese compounds (such as manganese-based catalysts), cobalt compounds (such as cobalt acetate), germanium compounds (such as germanium dioxide), tin compounds (tin-based catalysts), In particular, antimony compounds such as antimony compounds can be mentioned.
[0064]
Examples of the antimony compound include antimony oxides (such as antimony trioxide and antimony pentoxide), antimony alkoxides (such as antimony glycoloxide), and fatty acid salts of antimony (such as antimony acetate). A preferred antimony compound is antimony oxide (particularly antimony trioxide). These antimony compounds can be used alone or in combination of two or more.
[0065]
Examples of the alkali metal compound include alkali metal hydroxide, carbonate, aliphatic carboxylate (acetate, butyrate, etc., preferably acetate), aromatic carboxylate (benzoate), phenolic hydroxyl group And a salt with a compound having a salt (such as a salt with phenol). Examples of the alkali metal include lithium, sodium and potassium (preferably sodium). Preferred alkaline earth metal compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium acetate, sodium acetate, potassium acetate and the like, especially sodium acetate. These alkali metal compounds can be used alone or in combination of two or more.
[0066]
The heat-shrinkable film of the present invention preferably has an intrinsic viscosity of 0.66 dl / g or more. If the intrinsic viscosity of the heat-shrinkable film is too small, the molecular weight of the polyester constituting the film will be low, so the durability of the shrinkage stress during heat shrinkage will decrease, and defects such as shrinkage whitening and shrinkage spots will easily occur. It becomes inferior to shrink finish and appearance. Moreover, if the molecular weight of polyester falls, the mechanical strength and tear resistance of a film will be reduced. The intrinsic viscosity is preferably 0.67 dl / g or more, more preferably 0.68 dl / g or more. Although details of the method for increasing the intrinsic viscosity of the film will be described later, for example, a method of using a high molecular weight polyester as the raw material of the film (for example, using a polyester having an intrinsic viscosity of 0.7 dl / g or more) Method), a method of using a hydrolysis-resistant polyester as the polyester (for example, a method of using a polyester having an acid value of 25 eq / ton or less), and / or heat when extruding the polyester to form a film. Examples include a method for suppressing decomposition and hydrolysis (for example, a method of extruding after preliminarily drying the raw material polyester to make the moisture content about 100 ppm or less).
[0067]
The polyester film of the present invention is a homopolyester or a copolyester obtained by a predetermined method to be described later (hereinafter, these homopolyesters and copolyesters are referred to as low foreign substance polyesters) as they are or as necessary. It can be manufactured by mixing with other polyesters (homopolyester, copolymerized polyester, etc.) and then extruding to form a film. The ratio of the other polyester is, for example, 100 parts by mass or less, preferably 50 parts by mass or less, and more preferably 10 parts by mass or less with respect to 100 parts by mass of the low foreign substance polyester.
[0068]
When the film of the present invention is composed of the low foreign substance polyester alone, it contains an alkaline earth metal compound, a phosphorus compound, and a polymerization metal-containing compound added by a predetermined method described later. This polyester is a copolyester containing a 1,4-cyclohexanedimethanol component.
[0069]
On the other hand, when a film is composed of a low foreign substance polyester and another polyester, as long as it contains an alkaline earth metal compound, a phosphorus compound, and a metal-containing compound for polymerization added by a predetermined method described later, a dicarboxylic acid is used. The acid component and the polyvalent carboxylic acid component are not particularly limited. That is, when the film is combined with other polyesters (homopolyester, copolymerized polyester) or the like, the ratio of 1,4-cyclohexanedimethanol may be within a predetermined range. Moreover, the low foreign substance polyester and the other polyester may contain the same metal-containing compound for polymerization, or may contain different metal-containing compounds for polymerization. For example, when the low foreign substance polyester contains an antimony compound, the other polyester may contain an antimony compound, and a metal-containing compound for polymerization other than the antimony compound (titanium compound, manganese compound, cobalt compound, germanium compound, Tin compounds and the like). The other polyester may be one kind or two or more kinds.
[0070]
The low foreign substance polyester can be produced by melt polymerization according to a conventional method, and may be produced by a polycondensation method (direct polymerization method) of an oligomer obtained by directly reacting a dicarboxylic acid and a glycol. You may manufacture according to the method (transesterification method) which carries out the transcondensation after making the dimethyl ester body of an acid and glycol transesterify. Moreover, you may manufacture according to another arbitrary manufacturing method.
[0071]
In the esterification step, the low foreign substance polyester is produced by adding an alkaline earth metal compound and a phosphorus compound used for the purpose of lowering the melt specific resistance value of the film or for other purposes at a predetermined timing.
[0072]
More specifically, when producing a low foreign substance polyester, the esterification step is divided into three or more steps with different degrees of esterification. The alkaline earth metal compound is added after the second step. The phosphorus compound is added in a plurality of steps after the step of adding the alkaline earth metal compound.
[0073]
The alkaline earth metal compound is added after the second step for the following reason. That is, in the esterification step, the reaction is started by supplying a dicarboxylic acid (dicarboxylic acid or its ester) and a polyhydric alcohol to the reaction vessel, and a diester or an oligomer of the dicarboxylic acid and the polyhydric alcohol is produced. To go. In the first step, the concentration of carboxylic acid groups is high because a large amount of dicarboxylic acid remains in the reaction system or the acid value of the oligomer is large. If an alkaline earth metal is added in the first step, the carboxylic acid group and the alkaline earth metal react to generate a large amount of insoluble foreign matter (such as an alkaline earth metal salt). On the other hand, when an alkaline earth metal compound is added after the second step, the concentration of the carboxylic acid group is lowered and the viscosity of the reaction system is also increased. Therefore, the alkaline earth metal compound and the carboxylic acid are increased. Since the probability of meeting with the group also decreases, the amount of insoluble foreign matter can be suppressed.
[0074]
Preferably, the alkaline earth metal compound is added in a step after the second step (for example, a step after the third step such as the third step). As it is added in a later step, dicarboxylic acid is reduced and the acid value of the oligomer is reduced, so that the amount of insoluble foreign matter produced can be further reduced.
[0075]
The reason why the phosphorus compound is added in the steps after the step in which the alkaline earth metal compound is added is to effectively incorporate the phosphorus compound into the reaction system. Phosphorus compounds are often in liquid form, and if added in the absence of alkaline earth metal compounds, the phosphorus compounds escape and are not effectively incorporated into the reaction system. When added in the presence, the alkaline earth metal compound traps the phosphorus compound, so that the phosphorus compound can be effectively incorporated into the reaction system. When the phosphorus compound is added in a plurality of steps, the phosphorus compound and the alkaline earth metal compound can be reacted without forming a large lump compared with the case where the phosphorus compound is added in a single step, and insoluble foreign matter is added. (Alkaline earth metal salt) can be reduced.
[0076]
For example, when a phosphorus compound is added in two steps, the ratio (first / second) between the addition amount of the first step and the addition amount of the second step is 10/90 to 90/10 (mass ratio). ) Grade, preferably about 30/70 to 70/30 (mass ratio), more preferably about 40/60 to 60/40 (mass ratio). Moreover, when adding in 3 steps or more, it is preferable that the addition amount of each step is substantially equal.
[0077]
Preferably, the first step among the plurality of steps of adding the phosphorus compound is the same as the step of adding the alkaline earth metal compound. When the alkaline earth metal compound and the phosphorus compound are added in the same step, the phosphorus compound can be more efficiently taken into the reaction system.
[0078]
The addition time of the metal-containing compound for polymerization is not particularly limited, and may be added at any stage from the initial stage to the final stage of the esterification process, and may be added after the esterification process is completed and before the start of the polymerization process. Good.
[0079]
The plurality of steps can be divided based on the acid value of the oligomer produced as the esterification proceeds. For example, when the esterification process is divided into three steps, the first to third steps are as follows.
[0080]
First step (initial stage of esterification process): start = when raw materials are charged; end = time when the acid value of the oligomer is about 1400-3200 eq / ton
Second step (mid-stage of esterification process): initial stage = after completion of the first step; final stage = period when the acid value of the oligomer is about 800 to 1200 eq / ton
3rd step (late stage of esterification step): start = after end of 2nd step; end = time when oligomer acid value is about 250-600 eq / ton
Further, when dividing into four or more steps, for example, the steps can be divided by dividing (for example, equally dividing) the third step.
[0081]
The acid value (eq / ton) of the oligomer was 0. 1 g of a sample dissolved in 50 ml of a pyridine-water mixed solvent [pyridine / water = 4/1 (volume ratio)] and then phenolphthalein as an indicator. It can be titrated with a 1M aqueous sodium hydroxide solution and calculated based on the following formula.
[0082]
Acid value (eq / ton) = [(A−B) × 0.1 × F / (Wg × 10^Three]] × 10⁶
[In the formula, A indicates the titration amount (ml) of the aqueous sodium hydroxide solution, and B indicates the titration amount (ml) of the aqueous sodium hydroxide solution when titrated under the same conditions as described above (blank) except that no sample is added. ). F represents the factor of the aqueous sodium hydroxide solution. Wg represents the mass (g) of the sample]
The number of steps is not particularly limited as long as it is 3 or more, but it is preferably 5 steps or less from the viewpoint of polyester production efficiency.
[0083]
In the present invention, all steps of the esterification process may be performed with a single reaction vessel, or a plurality of reaction vessels may be used. When using a plurality of reaction cans, different reaction cans may be used each time the step progresses.
[0084]
It is desirable that the esterification step be carried out at about normal pressure (atmospheric pressure) or under pressure. If the esterification step is performed under reduced pressure, the alkaline earth metal compound or phosphorus compound may escape. The pressure (absolute pressure) in the esterification step is, for example, 90 kPa or more (preferably 100 kPa or more). If the pressure is too high, the amount of by-produced diethylene glycol (DEG) increases and the softening point of the polyester may decrease. Therefore, the pressure (absolute pressure) in the esterification step is desirably 400 kPa or less (preferably 294 kPa or less), for example.
[0085]
The reaction temperature of an esterification process is about 240-280 degreeC, for example, Preferably it is about 255-265 degreeC. If the reaction temperature is too low, the oligomer solidifies and the reaction rate tends to decrease. On the other hand, when the reaction temperature is too high, the amount of by-produced diethylene glycol (DEG) tends to increase, and the resulting polymer tends to be colored.
[0086]
The ratio of the dicarboxylic acid and polyhydric alcohol used in the esterification step is not particularly limited, but the acid value of the resulting polyester can be controlled by controlling the ratio of the dicarboxylic acid and polyhydric alcohol. The ratio of the polyhydric alcohol is, for example, about 1.7 to 2.5 mol, preferably about 1.8 to 2.4 mol, and more preferably 1.9 to 2.3 mol, with respect to 1 mol of the dicarboxylic acid. Degree.
[0087]
The ester and oligomer obtained by the esterification step can be produced according to a conventional polymerization method to produce a low foreign matter polyester.
[0088]
On the other hand, other polyesters for mixing with the low foreign substance polyester are not particularly limited. For example, the polyester is obtained in the same manner as the low foreign substance polyester except that the alkaline earth metal compound and the phosphorus compound are not added in the esterification step. Polyesters obtained may be used. Furthermore, the other polyester and the low foreign substance polyester may be the same or different in polymerization catalyst, dicarboxylic acid component, polyhydric alcohol component and the like.
[0089]
The polyester obtained by polymerizing the ester and the oligomer as described above (low-foreign polyester, other polyester, etc.) is preferably formed into chips after filtering the reaction product. Filtration can further reduce insoluble foreign matter. In the filtration, for example, a filter having an opening of about 3 to 20 μm can be used.
[0090]
The acid value of the polyester is not particularly limited, but is preferably about 10 to 25 eq / ton. When the acid value is too small, the polymerization productivity is lowered. On the other hand, if the acid value is too large, the hydrolysis resistance at the time of extrusion processing to form a film is lowered, and the intrinsic viscosity of the film is lowered.
[0091]
The intrinsic viscosity of the polyester is not particularly limited, but may be, for example, 0.68 dl / g or more, preferably 0.69 dl / g or more, more preferably 0.70 dl / g or more. If the intrinsic viscosity of the polyester is high, the intrinsic viscosity of the film can also be increased. A polyester having a high intrinsic viscosity can be produced by increasing the degree of progress of the polymerization reaction. The intrinsic viscosity of polyester is usually 1.3 dl / g or less.
[0092]
The polyester (polyester chip or the like) is preferably dried in advance when it is formed into a film. By drying, thermal decomposition and hydrolysis in the subsequent extrusion process can be reduced. The moisture content in the dried polyester is, for example, 100 ppm (mass basis) or less.
[0093]
When drying, a dryer such as a hopper dryer, a paddle dryer, or a vacuum dryer may be used, and a film can be produced by extruding the dried polyester at a temperature of 200 to 300 ° C. using an extruder. Further, undried polyester may be supplied to a vent type extruder, and moisture may be removed in the extruder. And a film can be manufactured by extruding while removing moisture.
[0094]
For the extrusion, any of various known methods (T-die method, tubular method, etc.) may be adopted. The extruded molten film is rapidly cooled with a casting roll to obtain an unstretched film.
[0095]
In the present invention, it is desirable to dispose an electrode between the extruder and the casting roll, apply a voltage between the electrode and the casting roll, and electrostatically adhere the film to the roll. Since the film of the present invention contains an alkaline earth metal compound and a phosphorus compound, the melt specific resistance value is low and the electrostatic adhesion is excellent. Therefore, the productivity of the film can be increased by applying a voltage.
[0096]
A heat-shrinkable polyester film can be produced by stretching the unstretched film. In the stretching process, it is practical in terms of production efficiency that the maximum shrinking direction is the film transverse (width) direction, and therefore an example of a stretching method in the case where the main shrinking direction is the transverse direction is shown below. Even when the maximum shrinkage direction is the longitudinal (longitudinal) direction of the film, the film can be stretched according to ordinary operations such as changing the stretching direction by 90 ° in the following method.
[0097]
When paying attention to uniforming the thickness distribution of the heat-shrinkable polyester film, it is preferable to perform a preheating step prior to the stretching step when stretching in the lateral direction using a tenter or the like. The thermal conductivity coefficient is 0.00544 J / cm²・ Sec ・ ℃ (0.0013 calories / cm²It is preferable to carry out heating until the film surface temperature reaches a certain temperature within the range of Tg + 0 ° C. to Tg + 60 ° C. at a low wind speed so that it becomes less than (sec · ° C.). The Tg represents a glass transition temperature.
[0098]
Stretching in the transverse direction is performed at a predetermined temperature within a range of Tg-20 ° C to Tg + 40 ° C, and is stretched 2.3 to 7.3 times, preferably 2.5 to 6.0 times. Thereafter, heat treatment is performed at a predetermined temperature in the range of 50 ° C. to 110 ° C. while stretching 0 to 15% or relaxing 0 to 15%, and if necessary, at a predetermined temperature in the range of 40 ° C. to 100 ° C. Further heat treatment is performed to obtain a heat-shrinkable polyester film.
[0099]
In this transverse stretching step, it is preferable to use equipment that can reduce the fluctuation of the film surface temperature. That is, the stretching process includes a preheating process before stretching, a stretching process, a heat treatment process after stretching, a relaxation process, a re-stretching process process, etc., and in particular, in the preheating process, the stretching process, and the heat treatment process after stretching. The fluctuation range of the surface temperature of the film measured at an arbitrary point is preferably within an average temperature ± 1 ° C., and more preferably within an average temperature ± 0.5 ° C. If the fluctuation range of the surface temperature of the film is small, the film is stretched or heat-treated at the same temperature over the entire length of the film, so that the heat shrinkage behavior becomes uniform.
[0100]
Examples of the equipment that can reduce the fluctuation of the film surface temperature include, for example, equipment equipped with a wind speed control means (such as an inverter) for controlling the supply speed of hot air for heating the film, and stably heating the air. Heating means for preparing the hot air [50 kPa or less (5 kgf / cm²And the like), and the like.
[0101]
As a stretching method, not only horizontal uniaxial stretching with a tenter, but also stretching in the longitudinal direction by 1.0 to 4.0 times, preferably 1.1 to 2.0 times may be performed. When biaxial stretching is performed in this manner, either sequential biaxial stretching or simultaneous biaxial stretching may be performed, and restretching may be performed as necessary. In the sequential biaxial stretching, the stretching order may be any method such as vertical and horizontal, horizontal and vertical, vertical and horizontal and horizontal and vertical and horizontal.
[0102]
Focusing on the point of suppressing the internal heat generation of the film accompanying stretching and reducing the film temperature unevenness in the width direction, the heat transfer coefficient of the stretching process is 0.00377 J / cm.²・ Sec ・ ℃ (0.0009 calories / cm²· Sec · ° C) or more is preferable. 0.00544-0.00837 J / cm²・ Sec ・ ℃ (0.0013 ～ 0.0020calories / cm²· Sec · ° C) is more preferable.
[0103]
The thickness of the heat-shrinkable polyester film of the present invention is not particularly limited. For example, the heat-shrinkable polyester film for labels is preferably 10 to 200 μm, and more preferably 20 to 100 μm.
[0104]
The film may contain fine particles such as silica, titanium dioxide, kaolin, and calcium carbonate, an antioxidant, an ultraviolet absorber, an antistatic agent, a colorant, an antibacterial agent, and the like, if necessary.
[0105]
【Example】
Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are not intended to limit the present invention, and modifications and implementations within the scope of the present invention are included in the present invention. In addition, the composition of the chip | tip and film obtained by the Example and the comparative example, and the measuring method of a physical property are as follows.
[0106]
(1) Film composition
(1) Dicarboxylic acid component, polyhydric alcohol component
A sample (chip or film) is dissolved in a solvent in which chloroform D (manufactured by Yurisop) and trifluoroacetic acid D1 (manufactured by Yurisop) are mixed at 10: 1 (volume ratio) to prepare a sample solution, Using “GEMINI-200” (manufactured by Varian), the proton NMR of the sample solution was measured under the measurement conditions of a temperature of 23 ° C. and an integration count of 64 times. Based on the peak intensity of protons measured by NMR measurement, the composition ratio of monomers constituting the sample was calculated.
[0107]
(2) Metal component
The contents of Na, Mg, Sb, Ti and P contained in the sample (chip or film) were measured according to the following method.
[0108]
[Na]
2 g of a sample was put in a platinum crucible and incinerated and decomposed at a temperature of 500 to 800 ° C., 5 ml of hydrochloric acid (concentration: 6 mol / L) was added and evaporated to dryness. The residue was dissolved in 10 ml of 1.2 mol / L hydrochloric acid, and the Na concentration was measured (calibration curve method) using an atomic absorption spectrometer [“AA-640-12”; manufactured by Shimadzu Corporation).
[0109]
[Mg]
2 g of a sample was put in a platinum crucible and incinerated and decomposed at a temperature of 500 to 800 ° C., 5 ml of hydrochloric acid (concentration: 6 mol / L) was added and evaporated to dryness. The residue was dissolved in 10 ml of 1.2 mol / L hydrochloric acid, and the Mg concentration was measured (calibration curve method) using an ICP emission spectrometer [“ICPS-200”; manufactured by Shimadzu Corporation).
[0110]
[Sb]
The sample was wet decomposed in sulfuric acid / hydrogen peroxide system. Sodium sulfite is added to ionize Sb (Sb⁵⁺After that, brilliant green was added to form a blue complex of Sb. After extracting this complex by adding toluene, the concentration of Sb complex in toluene is determined by measuring the absorbance at 625 nm using an absorptiometer [“UV-150-02”; manufactured by Shimadzu Corporation]. (Calibration curve method).
[0111]
[Ti]
The sample was placed in a platinum crucible and incinerated and decomposed, and then sulfuric acid and potassium hydrogen sulfate were added and heated to melt. After diluting with sulfuric acid (concentration: 2 mol / L), hydrogen peroxide was added. The concentration of the yellow complex of Ti was determined by measuring the absorbance at 420 nm using an absorptiometer [“UV-150-02”; manufactured by Shimadzu Corporation) (calibration curve method).
[0112]
[P]
Using the sample, the phosphorus component in the sample was converted to normal phosphoric acid by any of the following methods (A) to (C). This orthophosphoric acid and molybdate were reacted in sulfuric acid (concentration: 1 mol / L) to obtain phosphomolybdic acid, and then reduced by adding hydrazine sulfate. The density | concentration of the produced heteropoly blue was calculated | required by measuring the light absorbency of 830 nm using the absorptiometer ["UV-150-02"; Shimadzu Corporation make] (calibration curve method).
[0113]
(A) A sample and sodium carbonate are put into a platinum crucible and subjected to dry ashing decomposition.
[0114]
(B) Wet decomposition in sulfuric acid / nitric acid / perchloric acid system
(C) Wet decomposition in sulfuric acid / perchloric acid system
(2) Insoluble Mg amount and insoluble Sb amount
100 g of a sample (chip or film) was dissolved in a mixed solution of p-chlorophenol and tetrachloroethane [capacity 5 L; p-chlorophenol / tetrachloroethane = 75/25 (mass ratio)]. It filtered with the membrane filter (average pore diameter of 0.1 micrometer) made from a fluoroethylene, and dried the said filter. The concentrations of Mg and Sb in the insoluble matter collected on the filter were analyzed using fluorescent X-rays, and the amount of insoluble Mg and the amount of insoluble Sb (mg) in 1 kg of the sample were calculated.
[0115]
(3) Melt specific resistance value
A pair of electrode plates was inserted into a sample (chip or film) melted at a temperature of 275 ° C., and a voltage of 120 V was applied. The current was measured, and the melt specific resistance value (Si; unit Ω · cm) was determined based on the following formula.
[0116]
Si (Ω · cm) = (A / I) × (V / io)
[Where A is the electrode area (cm²), I represents the distance between electrodes (cm), V represents voltage (V), and io represents current (A)]
(4) Intrinsic viscosity
0.1 g of a sample (film or chip) was precisely weighed and dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane = 3/2 (mass ratio), and then measured with an Ostwald viscometer at 30 ± 0.1 ° C. The intrinsic viscosity [η] is obtained by the following formula (Huggins formula).
[0117]
[Expression 1]

[0118]
η_sp: Specific viscosity
t₀: Dropping time of solvent using Ostwald viscometer
t: Fall time of the film solution using an Oswald viscometer
C: Concentration of the film solution.
[0119]
In the actual measurement, the intrinsic viscosity was calculated by the following approximate equation where k = 0.375 in the Huggins equation.
[0120]
[Expression 2]

[0121]
η_r: Relative viscosity
  (5) Castability
  An electrode made of tungsten wire is disposed between a T die of the extruder and a casting roll whose surface temperature is controlled to 30 ° C., and a voltage of 7 to 10 kV is applied between the electrode and the casting roll. A resin having a thickness of 180 μm is produced by melt-extruding the resin from the T-die at a temperature of 280 ° C. and cooling with a casting roll (casting roll speed: 30 m / min). Pinner bubbles generated on the surface of the obtained film were visually observed and evaluated according to the following criteria.
[0122]
Y: No pinner bubble
Δ: Partial occurrence of pinner bubble is observed
×: Large occurrence of pinner bubble
(6) Thermal shrinkage
The film is cut into a 10 cm × 10 cm square, immersed in warm water at 85 ° C. ± 0.5 ° C. for 10 seconds under no load condition, and thermally contracted, then in water at 25 ° C. ± 0.5 ° C. for 10 seconds. After soaking, the lengths in the vertical and horizontal directions of the sample were measured, and the values were obtained according to the following formula.
Heat shrinkage rate (%) = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage)
The direction with the largest shrinkage rate was defined as the maximum shrinkage direction.
[0123]
(7) Thickness distribution
The film was cut into a length of 50 cm and a width of 5 cm (thickness measurement sample). Ten samples were prepared, and for each sample, the thickness was measured in the length direction using a contact-type thickness meter [“KG60 / A”; manufactured by Anritsu Co., Ltd.], and the thickness distribution was obtained based on the following formula: The average value was taken as the film thickness distribution.
[0124]
Thickness distribution = (maximum thickness−minimum thickness) / average thickness × 100
(8) Maximum heat shrinkage stress value
Using a tensile tester with a heating furnace (“Tensilon” manufactured by Toyo Seiki Co., Ltd.), a sample having a length of 200 mm in the maximum shrinkage direction and a width of 20 mm was cut out from the heat-shrinkable film and heated in advance to 90 ° C. The sample is attached to the chuck at a position of 50 mm from both ends of the sample so that the distance between the chucks becomes 100 mm, and then the heating furnace door is immediately closed and the blowing is resumed to detect the contraction stress. The maximum value obtained by measurement and obtained from the chart was defined as the maximum heat shrinkage stress value (MPa).
[0125]
(9) Shrinkage finish
The film was bonded with a solvent to produce a tube. In addition, about the thing which could not carry out solvent adhesion, heat sealing was performed and the tube was manufactured. The tube was cut to produce a heat-shrinkable polyester film label. Next, after attaching a label to a glass bottle having a capacity of 300 ml, the label was shrunk by passing through a hot air heat shrink tunnel of 160 ° C. (wind speed 10 m / sec) for 13 seconds. The degree of shrinkage whitening and shrinkage spots was judged visually, and the shrinkage finish was evaluated in five stages. Standards are 5: Best finish, 4: Good finish, 3: Shrinkage whitening or slight shrinkage spots (within 2 places), 2: Shrinkage whitening or shrinkage spots (3-5 places), 1: Shrinkage whitening or As the number of shrinkage spots (6 or more), 4 or more was judged as acceptable, and 3 or less was judged as defective.
[0126]
(10) Solvent adhesion
After leaving the film wrapped in a paper tube for 250 hours in a thermo-hygrostat controlled at an ambient temperature of 30 ° C. ± 1 ° C. and a relative humidity of 85 ± 2%, the film is taken out, and is taken out by Toyo Ink Mfg. Co., Ltd. After printing three colors with white ink, using a center seal machine, make a tube by solvent-bonding with a mixed solvent of 1,3-dioxolane / acetone = 80/20 (mass ratio), and wind it in a folded state It was. The tube roll was left in a constant temperature and humidity chamber at a temperature of 23 ° C. ± 1 ° C. and a relative humidity of 65% ± 2% for 24 hours, then taken out, rolled up, and checked for adhesion. Evaluation was made with x indicating a part that was easily peeled by hand, △ indicating that it was peeled by hand with a light resistance, and ○ indicating that there was no part easily peeled by hand. ○ is a pass.
[0127]
(11) Fisheye amount
The film was cut to prepare 10 2 cm × 2 cm sample films. Each sample film was observed with an optical microscope, and the number of fish eyes having a size of 20 μm or more was counted. The measurement results for 10 sample films are averaged, and the average value is used for 100 cm.^ThreeThe number of fish eyes per hit was determined.
[0128]
Synthesis Example 1 (Synthesis of polyester)
[Esterification process]
A continuous esterification reaction apparatus in which three complete mixing tanks (first mixing tank, second mixing tank, and third mixing tank) are connected is used. Each mixing tank includes a stirrer, a partial condenser (refluxing device), a raw material charging port, and a product outlet port.
[0129]
In addition to supplying terephthalic acid (TPA) to the first mixing tank (first esterification reaction can) at a supply rate of 2 tons / hr, 2 mol of ethylene glycol (EG) is supplied to 1 mol of TPA, and further trioxide is added. Antimony was supplied. In addition, antimony trioxide is the amount of Sb atoms when the terephthalic acid (TPA) is converted to polyethylene terephthalate (PET) in a yield of 100 mol% (hereinafter referred to as the theoretical final product amount). In an amount of 160 ppm (based on mass). Esterification was carried out while distilling water and ethylene glycol under conditions of a temperature of 255 ° C., a pressure = normal pressure, and an average residence time of 4 hours.
[0130]
The product (acid value = 1750 eq / ton) of the first mixing tank (first esterification reaction can) was continuously transferred to the second mixing tank (second esterification reaction can). Further, ethylene glycol distilled from the first mixing tank, an ethylene glycol solution of magnesium acetate, and an ethylene glycol solution of trimethyl phosphate (TMPA) were supplied to the second mixing tank in the amounts shown below. The esterification was further continued while distilling water and ethylene glycol under the conditions of a temperature of 260 ° C., a pressure = normal pressure, and an average residence time of 1.5 hours.
[0131]
Ethylene glycol distilled from the first mixing tank: Supply amount = 8% by mass with respect to the theoretical final product amount
Magnesium acetate: supply amount = amount at which the amount of Mg atoms is 65 ppm (mass basis) relative to the theoretical final product amount
TMPA: Amount of supply = amount of P atoms to be 20 ppm (mass basis) with respect to the theoretical final product amount
The product (acid value = 950 eq / ton) of the second mixing tank (second esterification reaction can) was continuously transferred to the third mixing tank (third esterification reaction can). Further, an ethylene glycol solution of TMPA was supplied to the third mixing tank in an amount such that the amount of phosphorus atoms was 20 ppm (mass basis) with respect to the theoretical final product amount [addition amount of TMPA in the second mixing tank: Addition amount of TMPA in 3 mixing tanks = 1: 1 (mass ratio)]. The esterification was further continued while distilling water and ethylene glycol under the conditions of a temperature of 260 ° C., a pressure = normal pressure, and an average residence time of 0.5 hour.
[0132]
[Polymerization process]
The ester (acid value = 300 eq / ton) produced in the third mixing tank is continuously supplied to a three-stage continuous polymerization reactor to perform polycondensation [total polymerization time of first to third polymerization tanks ( Residence time) = 4 hours], a polyester was produced and discharged into water in the form of a strand. The discharged material was cut with a strand cutter to obtain polyester chip A (intrinsic viscosity: 0.73 dl / g).
[0133]
Synthesis example 2
[Esterification process]
A continuous esterification reaction apparatus in which two complete mixing tanks (first mixing tank and second mixing tank) are connected is used. Each mixing tank includes a stirrer, a partial condenser, a raw material charging port, and a product outlet.
[0134]
While supplying terephthalic acid (TPA) to the first mixing tank (first esterification reaction can) at a supply rate of 2 tons / hr, 2 mol of ethylene glycol (EG) is supplied to 1 mol of TPA, and further trioxide Antimony, an ethylene glycol solution of magnesium acetate, and an ethylene glycol solution of TMPA were supplied in the amounts shown below. Esterification was carried out while distilling water and ethylene glycol under conditions of a temperature of 255 ° C., a pressure = normal pressure, and an average residence time of 4 hours.
[0135]
Antimony trioxide: supply amount = amount at which the amount of Sb atoms is 160 ppm (mass basis) with respect to the theoretical final product amount
Magnesium acetate: supply amount = amount at which the amount of Mg atoms is 65 ppm (mass basis) relative to the theoretical final product amount
TMPA: Amount of supply = amount of P atoms to be 20 ppm (mass basis) with respect to the theoretical final product amount
The product (acid value = 1750 eq / ton) of the first mixing tank (first esterification reaction can) was continuously transferred to the second mixing tank (second esterification reaction can). Further, ethylene glycol distilled from the first mixing tank and an ethylene glycol solution of TMPA were supplied to the second mixing tank in the amounts shown below. The esterification was further continued while distilling water and ethylene glycol under the conditions of a temperature of 260 ° C., a pressure = normal pressure, and an average residence time of 1.5 hours.
[0136]
Ethylene glycol distilled from the first mixing tank: Supply amount = 8% by mass with respect to the theoretical final product amount
TMPA: Amount of supply = amount of P atoms to be 20 ppm (mass basis) with respect to the theoretical final product amount
[Polymerization process]
The ester produced in the second mixing tank was continuously supplied to a three-stage continuous polymerization reactor, and a polyester chip B was obtained in the same manner as in Synthesis Example 1 (Intrinsic viscosity: 0.72 dl / g).
[0137]
Synthesis example 3
Instead of supplying 2 mol of EG to 1 mol of TPA in the first mixing tank, 1.36 mol of EG is supplied to 1 mol of TPA, and 1,4-cyclohexanedimethanol (CHDM) is supplied to 1 mol of TPA. A polyester chip C was obtained in the same manner as in Synthesis Example 1 except that 0.64 mol was supplied (Intrinsic viscosity: 0.78 dl / g).
[0138]
Synthesis example 4
Instead of supplying 2 mol of EG to 1 mol of TPA in the first mixing tank, 1.36 mol of EG is supplied to 1 mol of TPA, and 1,4-cyclohexanedimethanol (CHDM) is supplied to 1 mol of TPA. Polyester chip D was obtained in the same manner as in Synthesis Example 2 except that 0.64 mol was supplied (Intrinsic viscosity: 0.76 dl / g).
[0139]
Synthesis example 5
Instead of supplying 2 mol of EG to 1 mol of TPA in the first mixing tank, 2 mol of 1,4-butanediol (BD) is supplied to 1 mol of TPA, and antimony trioxide in the first mixing tank. Instead of supplying 160 ppm (mass basis) with respect to the theoretical final product amount in terms of the amount of Sb atoms, 15 ppm (mass basis) of titanium tetrabutoxide with respect to the theoretical final product amount in terms of Ti atoms A polyester chip E was obtained in the same manner as in Synthesis Example 1 except that EG was not added in the point and in the second mixing tank (intrinsic viscosity: 0.90 dl / g).
[0140]
Synthesis Example 6
A polyester chip F was obtained in the same manner as in Synthesis Example 5 except that 1,3-propanediol was used instead of 1,4-butanediol (BD) (intrinsic viscosity: 0.88 dl / g).
[0141]
Table 1 shows the compositions and physical properties of the polyester chips A to F obtained in Synthesis Examples 1 to 6.
[0142]
[Table 1]

[0143]
In the table, the content of inorganic components (Mg, P, Sb, Ti) is indicated by the concentration of each atom (unit: ppm; mass basis). The meaning of each abbreviation is as follows.
[0144]
TPA: terephthalic acid
EG: Ethylene glycol
CHDM: 1,4-cyclohexanedimethanol
BD: 1,4-butanediol
PD: 1,3-propanediol
Sb₂O_Three: Antimony trioxide
Mg (OAc)₂: Magnesium acetate
Ti (OBu)_Four: Titanium tetrabutoxide
TMPA: Trimethyl phosphate
Example 1
Each chip obtained in the above synthesis example was separately pre-dried, mixed with 37% by mass of chip A, 53% by mass of chip C, and 10% by mass of chip E, and using a single screw extruder. It was melt-extruded at a temperature of 280 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated at 91 ° C. for 10 seconds, and then stretched 4.0 times in the transverse direction at a temperature of 72 ° C. using a tenter, followed by heat treatment at a temperature of 79 ° C. for 10 seconds. A shrinkable polyester film was obtained. Table 2 shows the composition and physical property values of the dicarboxylic acid component and the polyhydric alcohol component in the obtained film.
[0145]
Example 2
Each chip obtained in the above synthesis example was separately pre-dried, mixed with 5% by weight of chip A, 70% by weight of chip C and 25% by weight of chip E, and using a single screw extruder. It was melt-extruded at a temperature of 280 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated at a temperature of 78 ° C. for 10 seconds, then stretched 4.0 times in the transverse direction at a temperature of 73 ° C. using a tenter, and subsequently heat treated at a temperature of 80 ° C. for 10 seconds to obtain a thickness of 45 μm. A heat-shrinkable polyester film was obtained. Table 2 shows the composition and physical property values of the dicarboxylic acid component and the polyhydric alcohol component in the obtained film.
[0146]
Comparative Example 1
Each chip obtained in the above synthesis example was separately pre-dried, mixed with 37% by mass of chip B, 53% by mass of chip D, and 10% by mass of chip E, and using a single-screw extruder. It was melt-extruded at a temperature of 280 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated at a temperature of 91 ° C. for 10 seconds, and then stretched 4.0 times in the transverse direction at a temperature of 72 ° C. using a tenter, followed by heat treatment at a temperature of 79 ° C. for 10 seconds, and a thickness of 45 μm. A heat-shrinkable polyester film was obtained. Table 2 shows the composition and physical property values of the dicarboxylic acid component and the polyhydric alcohol component in the obtained film.
[0147]
Comparative Example 2
Each chip obtained in the above synthesis example was separately pre-dried, mixed at a ratio of 5% by mass of chip B, 70% by mass of chip D and 25% by mass of chip E, and using a single-screw extruder. It was melt-extruded at a temperature of 280 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated at a temperature of 78 ° C. for 10 seconds, then stretched 4.0 times in the transverse direction at a temperature of 73 ° C. using a tenter, and subsequently heat treated at a temperature of 80 ° C. for 10 seconds to obtain a thickness of 45 μm. A heat-shrinkable polyester film was obtained. Table 2 shows the composition and physical property values of the dicarboxylic acid component and the polyhydric alcohol component in the obtained film.
[0148]
Comparative Example 3
Each chip obtained in the above synthesis example was separately pre-dried, mixed with 64% by mass of chip A, 10% by mass of chip C and 26% by mass of chip E, and using a single screw extruder. It was melt-extruded at a temperature of 280 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated at a temperature of 105 ° C. for 10 seconds, then stretched 4.0 times in the transverse direction at a temperature of 73 ° C. using a tenter, and subsequently heat treated at a temperature of 76 ° C. for 10 seconds to obtain a thickness of 45 μm. A heat-shrinkable polyester film was obtained. Table 2 shows the composition and physical property values of the dicarboxylic acid component and the polyhydric alcohol component in the obtained film.
[0149]
Example 3
Each chip obtained in the above synthesis example was separately pre-dried, mixed with 34% by mass of chip A, 53% by mass of chip C, and 13% by mass of chip F, and using a single screw extruder. It was melt-extruded at a temperature of 280 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated at 91 ° C. for 10 seconds, and then stretched 4.0 times in the transverse direction at a temperature of 72 ° C. using a tenter, followed by heat treatment at a temperature of 79 ° C. for 10 seconds. A shrinkable polyester film was obtained. Table 2 shows the composition and physical property values of the dicarboxylic acid component and the polyhydric alcohol component in the obtained film.
[0150]
[Table 2]

[0151]
In the table, the content of inorganic components (Mg, P, Sb, Ti) is indicated by the concentration of each atom (unit: ppm; mass basis). The meaning of each abbreviation is as follows.
[0152]
TPA: terephthalic acid
EG: Ethylene glycol
CHDM: 1,4-cyclohexanedimethanol
BD: 1,4-butanediol
PD: 1,3-propanediol
DEG: Diethylene glycol
[0153]
【The invention's effect】
Since the heat-shrinkable polyester film of the present invention contains a predetermined amount of 1,4-cyclohexanedimethanol component, it has good shrinkage at low temperatures and excellent shrinkage finish, and further has a predetermined production. Since it is manufactured by the method, the amount of insoluble foreign matter is small and a beautiful appearance can be obtained. Therefore, it can be suitably used for applications such as shrink labels, cap seals, shrink wrapping and the like.

Claims (8)

In heat shrinkable polyester film,
Of 100 mol% of the polyhydric alcohol component, 1,4-cyclohexanedimethanol component is 5 mol% or more,
A compound derived from a polymerization catalyst, at least one metal-containing compound for polymerization selected from a titanium compound, a manganese compound, a cobalt compound, a germanium compound, a tin compound, and an antimony compound;
An alkaline earth metal compound;
Containing a phosphorus compound,
A heat-shrinkable polyester film having the following properties (1) and (2).
(1) When a sample of a heat-shrinkable polyester film cut into a 10 cm × 10 cm square shape is dipped in hot water at 85 ° C. for 10 seconds, and then dipped in water at 25 ° C. for 10 seconds. The thermal shrinkage rate in the maximum shrinkage direction is 20% or more. (2) The amount of insoluble foreign matter having a particle size of 0.1 μm or more contained in 1 kg of film is caused by alkaline earth metal atom M ¹ and polymerization metal atom M ^{x in the} foreign matter. The total amount is 1 mg or less The content of alkaline earth metal atom M ^{2 in} the film is 40 ppm (mass basis) or more, the content of phosphorus atom is 20 ppm (mass basis) or more, and the content of metal atom M ^x for polymerization is 50 ppm (mass basis) or more. The heat-shrinkable polyester film according to claim 1. The heat-shrinkable polyester film according to claim 1 or 2, wherein a melt specific resistance value at a temperature of 275 ° C is 0.70 x 10 ⁸ Ω · cm or less. The heat shrinkable polyester according to any one of claims 1 to 3, wherein the atomic weight ratio (M ² / P) of the alkaline earth metal atom M ² and the phosphorus atom P in the film is 1.2 to 5.0. Film.   The heat-shrinkable polyester film according to any one of claims 1 to 4, wherein a proportion of the 1,4-cyclohexanedimethanol in 100 mol% of the polyhydric alcohol component is 10 to 80 mol%.   The heat-shrinkable polyester film according to any one of claims 1 to 5, which has an intrinsic viscosity of 0.66 dl / g or more.   The heat-shrinkable polyester film according to any one of claims 1 to 6, wherein the alkaline earth metal atom is magnesium. A heat-shrinkable polyester-based label, which is obtained from the heat-shrinkable polyester-based film according to any one of claims 1 to 7.