JP2004181863A - Heat shrinkable polyester type film roll and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat shrinkable polyester type film roll able to produce a heat shrinkable label or the like reducing a scatter in performance per a product by suppressing a fluctuation of a masking power in the film roll. <P>SOLUTION: The film roll is made by winding up the heat shrinkable polyester type film containing inorganic and/or organic fine particles and the film has a heat shrinkage factor of≥ 20% under a specific condition, and on observing a total light transmittance for a plurality of samples taken in a specific condition and calculating an average value of the total light transmittance for each sample, the total light transmittance of the each sample is ≤ 40% and at the same time is kept in a range of the average value ±1.5%. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０１１４】
ここで、η_ｓｐ ：比粘度、ｔ_０：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である。
【０１１５】
なお、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する。
【０１１６】
【数２】

【０１１７】
ここで、η_ｒ：相対粘度である。
【０１１８】
（４）全光線透過率
上記（１）における各試料切り出し部から、フィルムの走行方向およびその直交方向に沿うように５０ｍｍ×５０ｍｍの正方形の試料を各３個採取し、日本電飾工業株式会社製「ＮＤＨ−２０００Ｔ」を用い、ＪＩＳ Ｋ ７１３６に準じて測定する。結果を表５に示す。
【０１１９】
表５において、平均値（Ｘ）は測定した１１試料の全ての全光線透過率（％）の平均値を、最大値（Ｙｍａｘ）は１１試料のうちの全光線透過率の最大値を、最小値（Ｙｍｉｎ）は１１試料のうち最小の全光線透過率を夫々示し、平均値との差も示す。
【０１２０】
（５）熱収縮率
フィルムを走行方向およびその直交方向に沿うように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、直ちに２５℃±０．５℃の水中に１０秒浸漬し、その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する。結果を表５に示す。
【０１２１】
表５において、平均値（Ｒ）は測定した１１試料の全ての熱収縮率（％）の平均値を、最大値（Ｓｍａｘ）は１１試料のうちの熱収縮率の最大値を、最小値（Ｓｍｉｎ）は１１試料のうち最小の熱収縮率を夫々示し、平均値との差も示す。
【０１２２】
（６）溶剤接着強度
フィルムを長さ方向にスリットし、１，３−ジオキソランで溶剤接着してチューブを作り、これを平らに潰した状態で巻き取ってチューブロールとする。このチューブロールから切り出したチューブ状試料を切り開いて幅１５ｍｍのフィルム状試験片とし、このフィルム状試験片を、チャック間距離を２０ｍｍにセットした引張試験機（東洋精機社製「テンシロン ＵＴＬ−４Ｌ」）に、溶剤接着部がチャック同士の中央に位置するようにセットして、温度２３℃、引張速度２００ｍｍ／分の条件で引張試験を行い、溶剤接着部が剥がれる時の強度（溶剤接着強度）を測定する。測定値が４Ｎ／１５ｍｍ未満の場合を不良とし、不良サンプルを切り出した試料切り出し部の数を数え、下式
溶剤接着性不良率（％）＝１００×Ａ÷Ｂ
に従って溶剤接着性不良率（％）を算出する。なお、上記式中、Ａ：不良サンプルを切り出した試料切り出し部数（個）、Ｂ：全試料切り出し部数（個）である。結果を表６に示す。
【０１２３】
（７）収縮仕上り性
紙管に巻いた熱収縮性ポリエステル系フィルムロールを、温度３０℃±１℃、８５ＲＨ％±２％に制御した環境下で２５０時間保管し、これに東洋インキ製造社製の草色および金色のインキで２色印刷した後、フィルムをスリットし、続いて、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（平らに潰した状態）で巻き取る。このチューブロールを、温度２３℃±１℃、湿度６５ＲＨ％±３％の雰囲気下で２４時間保管した後、全量裁断して熱収縮性ポリエステル系フィルムラベルを作製する。フジ・アステック社製のスチームトンネル（型式：ＳＨ−１５００−Ｌ）を使用し、５００ｍＬのＰＥＴボトル（株式会社大和製罐社製で、株式会社サントリーの涼屋麦茶に使用されているボトル）に熱収縮性ポリエステル系フィルムラベルを装着して、トンネル通過時間５秒、ゾーン温度８０℃の条件で、作製したラベル全量を通過させ、収縮仕上り性を目視で判定する。試験数は１０００とする。収縮仕上り性は、目視で評価し、シワ、飛び上がり、収縮不良のいずれも観察されなかったものを合格、シワ、飛び上がり、または収縮不良が観察されたものを不合格とし、下式
収縮仕上り不良率＝１００×不良ラベル数÷全ラベル数
に従って、収縮仕上り性の不良率（％）を求める。結果を表６に示す。
【０１２４】
合成例１
撹拌機、温度計および部分還流式冷却器を備えたステンレススチール製オートクレーブに、多価カルボン酸類としてジメチルテレフタレート１００モル％、多価アルコール類としてエチレングリコール７０モル％、ジエチレングリコール２モル％、およびネオペンチルグリコール２８モル％を、多価アルコール類がモル比でメチルエステルの２．２倍になるように仕込み、エステル交換触媒として酢酸亜鉛を０．０５モル％（多価カルボン酸類に対して）と、重縮合触媒として三酸化アンチモン０．０２５モル％（多価カルボン酸類に対して）添加し、生成するメタノールを系外へ留去しながらエステル交換反応を行った。その後、２８０℃で２６．７Ｐａの減圧条件の下で重縮合反応を行い、固有粘度０．７２ｄｌ／ｇのポリエステル（ａ）を得た。重合後に、ポリエステルを溶融状態で重合装置からストランド状で取り出し、直ちに水冷し、その後、ストランドカッターでカットして、ポリエステルチップ（ａ）を得た。また、カット条件を変えて、少し小さいチップを作成した。これをポリエステルチップ（ｂ）とした。
【０１２５】
合成例２
合成例１と同様にして、表１に示す組成、表２に示すサイズおよび極限粘度のポリエステルチップ（ｃ）〜（ｆ）を得た。なお、表２のポリエステルチップ（ｇ）については、合成例１に記載のオートクレーブに、予備乾燥したポリエステルチップ（ｆ）とε−カプロラクトンを７０／３０（質量比）で仕込み、窒素ガス雰囲気中、２３０℃で２時間混合・反応させて合成した。また、表２のポリエステルチップ（ｃ’）は、ポリエステルチップ（ｃ）：５０質量％と酸化チタン（ＴｉＯ_２）微粒子（富士チタン社製「ＴＡ−３００」）：５０質量％を、夫々押出機直上のホッパに定量フィーダーで連続的に別々に供給しながら、このホッパ内で混合し、２８０℃で単軸押出機で溶融押出して得られるストランドを直ちに水冷し、その後、ストランドカッターでカットして得た。
【０１２６】
【表１】

【０１２７】
表１中、ＴＰＡはテレフタル酸成分を、ＥＧはエチレングリコール成分を、ＣＨＤＭは１，４−シクロヘキサンジメタノール成分を、ＮＰＧはネオペンチルグリコール成分を、ＢＤは１，４−ブタンジオール成分を、ＤＥＧはジエチレングリコール成分を、ε−ＣＬユニットはε−カプロラクトン由来のユニットを意味する。また、表１中、「多価カルボン酸成分」量は、チップ中の全多価カルボン酸成分量とε−カプロラクトン由来のユニット量の合計量１００モル％中の量を、「多価アルコール成分」量は、チップ中の全多価アルコール酸成分量とε−カプロラクトン由来のユニット量の合計量１００モル％中の量を意味し、「ε−ＣＬユニット」量は、チップ中のエステルユニット量（全多価カルボン酸成分量、または全多価アルコール成分量と同じ）とε−カプロラクトン由来のユニット量の合計量１００モル％中の量を意味する。
【０１２８】
【表２】

【０１２９】
実施例１
上記合成例で得られたチップを夫々別個に予備乾燥し、表３に示すように、Ａ層の原料としてチップ（ｃ）：７質量％、チップ（ｄ）：７３質量％およびチップ（ｆ）：２０質量％を、Ｂ層の原料としてチップ（ｄ）：５０質量％、チップ（ｆ）：２０質量％、チップ（ｃ’）：２０質量％および結晶性ポリスチレン樹脂（日本ポリスチレン株式会社製「Ｇ７９７Ｎ」）：１０質量％を用いた。
【０１３０】
Ａ層用原料はＡ層用の単軸押出機で、Ｂ層用原料はＢ層用の単軸押出機で、夫々２８０℃で溶融混練し、フィードブロックで接合したＴダイから、後記の延伸後の厚みでＡ層／Ｂ層／Ａ層＝１２．５μｍ／２５μｍ／１２．５μｍとなるように積層しながら押出し、チルロールで急冷して全厚さが２００μｍの未延伸フィルムを得た。なお、Ａ層、Ｂ層各原料の押出機への供給は、夫々の押出機直上のホッパに定量スクリューフィーダーで各チップを連続的に別々に供給しながら、これらのホッパ内で混合する方法を採用した。ホッパは、原料チップが１５０ｋｇ入る容量を有しており、各押出機の吐出量は、１時間当たり４５０ｋｇである。また、ホッパの傾斜角は７０°であった。
【０１３１】
表４に記載の条件で上記未延伸フィルムを予熱した後、テンターを用いて横方向に７５℃で４．０倍延伸し、その後８０℃で１０秒間熱処理して、全厚さ５０μｍ（Ａ層／Ｂ層／Ａ層＝１２．５μｍ／２５μｍ／１２．５μｍ）の熱収縮性ポリエステル系フィルムを１０００ｍ以上に亘って連続的に製膜した。フィルムを１０００ｍ連続製造したときのフィルム表面温度の変動幅は、予熱工程で平均温度±０．８℃、延伸工程で平均温度±０．６℃、熱処理工程で平均温度±０．５℃の範囲内に制御した。なお、フィルムの表面温度は、赤外式の非接触表面温度計を用いて測定した（以下の実施例、比較例でも同じ）。得られたフィルムを幅０．４ｍ、長さ１０００ｍにスリットして、３インチ紙管に巻き取り、熱収縮性ポリエステル系フィルムロールを得た。
【０１３２】
実施例２
原料組成を表３に示すように変更し、未延伸フィルムの予熱条件および延伸条件を表４に示すように変更した他は、実施例１と同様にして全厚み５０μｍ（Ａ層／Ｂ層／Ａ層＝１２．５μｍ／２５μｍ／１２．５μｍ）の熱収縮性ポリエステル系フィルムが巻回されたフィルムロールを製造した。
【０１３３】
すなわち、実施例１および２の熱収縮性ポリエステル系フィルムロールでは、微粒子含有チップを含むポリエステル原料チップ形状の適正化、ホッパ形状の適正化、およびホッパ容量の適正化といった手法を採用しており、長尺フィルムの全長に亘って組成の変動を小さくしている。また、延伸前の予備加熱条件を制御して、長尺フィルムの全長に亘ってフィルム内部までが延伸に適した温度となるようにしている。さらに、フィルム延伸の際に、予熱、延伸、熱処理の各工程で、該フィルムの表面温度の変動幅を、平均温度±１．０℃の範囲内に制御して、フィルムの全長に亘って各物性の変動を小さくしている。これらのフィルムロールのフィルムの特性値を表５および６に示す。
【０１３４】
比較例１
原料を押出機に投入する方法を下記のように変更した以外は、実施例１と同様にして全厚み５０μｍ（Ａ層／Ｂ層／Ａ層＝１２．５μｍ／２５μｍ／１２．５μｍ）の熱収縮性ポリエステル系フィルムが巻回されたフィルムロールを製造した。
【０１３５】
表３に示す配合で、Ａ層用原料およびＢ層用原料を夫々事前に混合し、予備乾燥した。Ａ層用、Ｂ層用別に、原料チップが４００ｋｇ入り、傾斜角が６０°である同一形状のホッパを４個直列に並べ、一番上流のホッパに上記乾燥後のチップ混合物を入れ、２個目、３個目、４個目（最終ホッパ）へと移動させて、Ａ層用押出機およびＢ層用押出機に投入した。
【０１３６】
比較例２
原料組成を表３に示すように変更し、未延伸フィルムの予熱条件および延伸条件を表４に示すように変更した他は、比較例１と同様にして全厚み５０μｍ（Ａ層／Ｂ層／Ａ層＝１２．５μｍ／２５μｍ／１２．５μｍ）の熱収縮性ポリエステル系フィルムが巻回されたフィルムロールを製造した。
【０１３７】
すなわち、比較例１および２の熱収縮性ポリエステル系フィルムロールでは、原料偏析の発生を抑制する手法を積極的に採用しておらず、長尺フィルムの全長に亘って組成の変動が大きくなっている例である。これらのフィルムロールのフィルムの特性値を表５および６に示す。
【０１３８】
比較例３、４
原料組成を表３に示すように変更し、未延伸フィルムの予熱条件および延伸条件を表４に示すように変更した他は、実施例１と同様にして全厚み５０μｍ（Ａ層／Ｂ層／Ａ層＝１２．５μｍ／２５μｍ／１２．５μｍ）の熱収縮性ポリエステル系フィルムが巻回されたフィルムロールを製造した。
【０１３９】
すなわち、比較例３および４の熱収縮性ポリエステル系フィルムロールは、原料偏析を抑制する手段を採用して長尺フィルムの全長に亘って組成の変動を小さくしており、フィルム延伸の際に、予熱、延伸、熱処理の各工程で、該フィルムの表面温度の変動幅を、平均温度±１．０℃の範囲内に制御して、フィルムの全長に亘って各物性の変動を小さくしているが、延伸前の予備加熱条件が不適であり、フィルム内部が延伸に適した温度となるように制御せずに製造した例である。これらのフィルムロールのフィルムの特性値を表５および６に示す。
【０１４０】
【表３】

【０１４１】
表３の「酸化チタン微粒子」は、ポリエステルチップ（ｃ’）に含有された形で供給されるため、その量を括弧書きで示している。
【０１４２】
【表４】

【０１４３】
【表５】

【０１４４】
【表６】

【０１４５】
表５および６から明らかなように、実施例１および２の熱収縮性ポリエステル系フィルムロールに巻回された長尺フィルムは、全光線透過率が小さく、フィルムの全長に亘ってその変動も抑えられている。すなわち、これらのフィルムは良好な光線カット性を有すると共に、これらのフィルムから得られる熱収縮性ラベルなどの個々の光線カット性のばらつきも抑制される。よって、例えば劣化し易い内容物に適用される容器などの被覆収縮ラベルなどの用途に好適である。
【０１４６】
【発明の効果】
本発明の熱収縮性ポリエステル系フィルムロールは、フィルムロールに巻回された長尺のフィルムの全光線透過率の変動が小さいため、該フィルムからラベルや袋などを作製した場合、個々の隠蔽性が良好であり、製品不良の発生率が極めて低い。また、本発明の熱収縮性ポリエステル系フィルムロールの製造方法は、容易に長尺フィルムの全光線透過率の変動を小さくすることができ、工業生産上において非常に有用なものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a film roll obtained by winding a heat-shrinkable polyester film and a method for producing the same, and more particularly to a film roll obtained by winding a heat-shrinkable polyester film suitable for label use and a method for producing the same. is there.
[0002]
[Prior art]
Conventionally, heat-shrinkable polyester films utilize the property of shrinking by heating, and are used for shrink wrapping and shrink labels, for example, in various containers such as polyethylene terephthalate (PET) containers, polyethylene containers, and glass containers. It is used for cap seals or integrated packaging.
[0003]
After production, these heat-shrinkable films are once wound up in a roll form, and sent in a form of this film roll to a printing process of various designs. After printing, if necessary, slitting is performed according to the size of the label used for the final product, and the left and right ends of the film are overlapped and sealed by means such as solvent bonding, etc. To be. This tubular body is cut and processed into a form such as a label or a bag. The inside of a shrink tunnel (steam tunnel) of a type in which a label or a bag-like material is attached to a container and blows steam to thermally shrink, or a shrink tunnel (hot wind tunnel) of a type that blows hot air to thermally shrink. Is passed through a belt conveyor or the like, and is thermally contracted to adhere to the container.
[0004]
By the way, recently, heat shrinkable labels have been increasingly used to protect the contents of containers from ultraviolet rays. Conventionally, UV-cut heat-shrinkable films made of polyvinyl chloride have been used.However, polyvinyl chloride has a problem of environmental impact during disposal, such as dioxin generation. There is a growing demand for heat shrinkable films of the type. For example, when the content of the container is a food or beverage, since these alterations and coloring are caused by ultraviolet rays in a long wavelength range such as 360 to 400 nm, a film having a concealing property capable of cutting off ultraviolet rays in such a long wavelength range is required. Desired. However, there was no conventional heat-shrinkable polyester film capable of sufficiently cutting the ultraviolet light in the long wavelength region.
[0005]
In a conventional heat-shrinkable film made of polyvinyl chloride or the like, in order to form an ultraviolet-cut film as described above, usually, white printing is performed after performing pattern printing on a surface corresponding to the inside of the label. However, the thickness of the printing ink layer formed by white printing is usually about 3 μm, which is not enough to shield light rays such as ultraviolet rays. In addition, although a method of performing the white printing twice has been attempted, there is a problem such as a change in heat shrinkage characteristics that can occur due to an increase in the thickness of the printing ink layer, and the manufacturing process and cost also increase. There is also a problem.
[0006]
In addition, since the same label or bag for the final product is usually processed from one film roll, the fluctuation of the concealing property (light shielding property for ultraviolet rays or the like) of the film wound on one film roll is changed. If the size is large, the concealing property of each label or bag changes, so that there is also a problem that the content of the bottle or the like in which these are easily changed is generated. Further, the appearance of the labels attached to the bottles may be different from each other.
[0007]
In addition, in the long heat-shrinkable film wound around the film roll, there is no known document that proposes a technique mainly aimed at suppressing a change in film characteristics such as the concealing property.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the fluctuation of the concealing property in a film roll and to manufacture a heat-shrinkable label or the like in which the variation in performance between products is reduced. An object of the present invention is to provide a heat-shrinkable polyester film roll.
[0009]
[Means for Solving the Problems]
The heat-shrinkable polyester film roll of the present invention (hereinafter sometimes simply referred to as “film roll”) is a film roll obtained by winding a heat-shrinkable polyester film containing inorganic and / or organic fine particles. , This heat-shrinkable polyester film is
(1) In the steady region where the physical properties of the film are stable in the longitudinal direction of the film, the end on the winding start side of the film is a first end, the end on the winding end side is a second end, and the second end A first sample cut-out portion is provided at a position within 2 m inside the portion, and a final sample cut-out portion is provided at a position within 2 m inside the first end portion, and about every 100 m from the first sample cut-out portion. A sample cut-out portion was provided, and a sample cut into a square of 10 cm × 10 cm from each sample cut-out portion was immersed in hot water of 85 ° C. for 10 seconds and pulled up, and then immersed in water of 25 ° C. for 10 seconds and pulled up. When the heat shrinkage in the maximum shrinkage direction is 20% or more for all the samples,
(2) When the total light transmittance of the sample separately cut out from each sample cutout section was measured, the total light transmittance of all the samples was 40% or less, and when the average value thereof was calculated, The gist exists where the total light transmittance falls within the range of ± 1.5% of this average value.
[0010]
The above-mentioned film roll has a small variation in the total light transmittance over the entire length of the stationary region of the film, that is, a small variation in the concealing property. Is reduced. Therefore, occurrence of defective products can be reduced in products such as containers produced by shrink-coating labels and the like manufactured from the film roll.
[0011]
In addition, from the viewpoint of increasing the film strength to some extent while securing the above total light transmittance, the heat-shrinkable polyester-based film preferably contains voids. In this case, the film is made of polyester. It is recommended that the system resin and the polyester resin contain a thermoplastic resin which is incompatible with the constituent resin.
[0012]
Further, from the viewpoint of enhancing the gloss of the film surface and the appearance of the printed surface while ensuring the total light transmittance, the heat-shrinkable polyester film has a surface layer on at least one surface, It is recommended that the surface layer has an inorganic and / or organic fine particle content of 0.2% by mass or less (including 0% by mass) with respect to the total amount of the surface layer and substantially does not contain voids. Is done. Here, “substantially does not contain a cavity” means, for example, excluding a cavity that is unavoidably formed in a film manufacturing process.
[0013]
Further, when the heat-shrinkable polyester film has a width of 0.2 m or more and a length of 300 m or more, the concealing property of the film easily changes unless the present invention is applied, and it is significant to apply the present invention. . Further, a film having the above width and length is a preferred embodiment of the present invention because it is excellent in workability and handleability in the above-described processing from printing to final product.
[0014]
A preferred method for producing the heat-shrinkable polyester film roll of the present invention in which the fluctuation of the total light transmittance of the film is suppressed is a production method including a step of melt-extruding a raw material polymer chip, The gist lies in that the entire amount of the inorganic and / or organic fine particles of the heat-shrinkable polyester film wound on the heat-shrinkable polyester film roll is previously contained in at least a part of the raw material polymer chip. . Furthermore, after the film obtained by cooling after melt extrusion of the raw material polymer is once wound, or after the cooling, the film is stretched to produce the above-mentioned heat-shrinkable polyester film roll by stretching, prior to stretching. It is preferable to preheat the heat-shrinkable polyester film by applying hot air to the upper and lower surfaces of the film under the following conditions (I) and (II). Here, when (I) the hot air blowing speed is 12 m / sec or more, (II) the temperature of the hot air is T1 (° C.), and the surface temperature of the film before preheating is T2 (° C.), 40 ≦ T1−T2 ≦ 90.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The heat-shrinkable polyester film roll of the present invention is a known polyvalent carboxylic acid component and a single copolymerized polyester having an ester unit formed from a polyhydric alcohol component as a main constituent unit, or a polyester of two or more polyesters. This is a film roll obtained by winding a heat-shrinkable polyester film (hereinafter, sometimes simply referred to as “film”) obtained by using the mixture. Hereinafter, the heat-shrinkable polyester film roll of the present invention will be described in detail.
[0016]
[Heat shrinkage]
The film according to the present invention, the end of the winding start side of the film in the steady region where the film physical properties are stable in the length direction of the film as the first end, the end of the winding end side as the second end, A first sample cutout portion is provided at a position within 2 m inside the second end portion, and a final sample cutout portion is provided at a position within 2 m inside the first end portion, and the first sample cutout portion is provided from the first sample cutout portion. Sample cutouts were provided at intervals of about 100 m. Samples cut into squares of 10 cm × 10 cm from each sample cutout were immersed in hot water at 85 ° C. for 10 seconds, pulled up, and then immersed in water at 25 ° C. for 10 seconds. The heat shrinkage in the maximum shrinkage direction when pulled up is 20% or more.
[0017]
In the film according to the present invention, each sample cut-out portion is provided in a steady region where film physical properties are stable in the length direction of the film. A heat-shrinkable film is produced by extruding a molten resin to form a film as described below, and then stretching the film. It fluctuates greatly. Further, even after the operation in the film forming step or the stretching step is stabilized, changing the film forming conditions or the stretching conditions will change the film properties. In the present invention, the technical idea is not to achieve a uniform concealment of the film obtained when the operation in the film forming step and the stretching step is unstable, the operation in these steps is stable, The purpose of the present invention is to achieve a highly uniform concealing property in a film having stable physical properties obtained when the production enters a steady state.
[0018]
In addition, the number of steady regions where the film properties are stable (the film portion obtained when the production enters a steady state) is usually one place in one film roll (the total length of the film wound on the film roll). Over a single location). However, depending on the manufacturing situation, the sample may be present at a plurality of locations. In this case, the sample cutout section may be provided only in the steady area. Further, the above-mentioned steady region can be evaluated, for example, by a heat shrinkage obtained by a measurement method described later. That is, a region where the heat shrinkage is stable within a range of about 20% or less (that is, the difference between the maximum value and the minimum value of the heat shrinkage of a plurality of samples is about 20% or less) may be regarded as a steady region.
[0019]
The method for collecting each of the above samples will be described in more detail. For example, a heat-shrinkable film having a length of 498 m is wound on a roll. In the film, a point 5 m from the end of the winding is a start end (that is, a second end) of a steady region, and a point 5 m from the start of the winding is a point. If it is the end of the constant region (ie, the first end), cut out the first sample (i) within 2 m from the second end. Subsequently, at a distance of 100 m from the cut portion, the second sample (ii) is cut. Similarly, a third sample (iii) is cut at 200 m, a fourth sample (iv) at 300 m, and a fifth sample (v) at 400 m. Here, since the remainder is shorter than 100 m, the sixth (final) sample (vi) cuts out any part within 2 m from the first end of the constant region.
[0020]
The thermal shrinkage in the maximum shrinkage direction is measured for a sample of 10 cm × 10 cm obtained from each of the sample cutouts. Here, the heat shrinkage in the maximum shrinkage direction means the heat shrinkage in the direction in which the sample shrinks most, and the maximum shrinkage direction is determined by the length of the square in the vertical or horizontal direction. The thermal shrinkage (%) was determined by immersing a 10 cm × 10 cm sample in hot water at 85 ° C. ± 0.5 ° C. for 10 seconds under no load for heat shrinkage, and then immediately subjecting the sample to 25 ° C. ± 0.5 mm. The film was immersed in water at 5 ° C under no load for 10 seconds, and the length of the film in the vertical and horizontal directions was measured, and the value was obtained according to the following formula (hereinafter, the heat in the maximum shrinkage direction measured under these conditions). The shrinkage is simply abbreviated as "thermal shrinkage."
Heat shrinkage = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage).
[0021]
When the heat shrinkage of the film is less than 20%, the heat shrinkage of the film is insufficient, and when the film is shrunk to cover a container or the like, the film does not adhere to the container and poor appearance occurs, which is not preferable. The more preferable heat shrinkage is 40% or more, further preferably 60% or more. Further, the heat shrinkage of the film is preferably 70% or less.
[0022]
[Hiding property]
Furthermore, the film according to the present invention measured the total light transmittance of the sample separately cut out from each of the sample cutout parts according to the provisions of JIS K 7136, and calculated the average value of the total light transmittance of all the samples. In this case, the total light transmittance of each sample must be 40% or less and fall within a range of ± 1.5% of the average value.
[0023]
The meaning of “the total light transmittance of each sample falls within a range of ± 1.5% of the average value of the total light transmittance of all samples” is as follows. The total light transmittance (%) of each sample cut out from each sample cutout section is measured by a method specified in JIS K 7136, and the average value (%) of the total light transmittance of all the samples is calculated. Assuming that the average value of the total light transmittance is X (%) and the content of the sample (i) (which means the number of the sample cutout portion; the same applies hereinafter) is Y1 (%), | X−Y1 | (Absolute value of X-Y1) is smaller than 1.5 (%), and | X-Yn | is similarly applied to the total light transmittances Y2 to Y6 (%) for the samples (ii) to (vi). Is smaller than 1.5 (%), which means that the average value of the total light transmittance is within ± 1.5%. In other words, if both the difference between the maximum value Ymax and X of Yn and the difference between minimum values Ymin and X are within ± 1.5%, the requirements of the present invention are satisfied.
[0024]
In the film according to the present invention, the total light transmittance of each sample cut out from each cutout portion must be 40% or less, preferably 35% or less, and more preferably 30% or less. If the film has a total light transmittance of not more than the above upper limit value, for example, it can cut incident ultraviolet rays by 25% or more. That is, in the case of a film having a total light transmittance of more than 40%, for example, when a label is made from the film and the container is covered with the label and shrunk, the content can be seen through the label from the outer surface side, or the content can be seen. The possibility of the occurrence of deterioration is increased. The fact that the contents can be seen through from the outer surface of the label means that a large amount of light (about 400 to 700 nm) having a wavelength in the visible light region is transmitted. Depending on the type of the contents, it may be required to shield these lights in order to contribute to the deterioration of the contents.
[0025]
In the film according to the present invention, as long as the total light transmittance is equal to or less than the upper limit, the color is not particularly limited, and may be a color according to the application of the film, but white is typical. is there.
[0026]
Further, the total light transmittance of each sample cut out from each of the cutout portions is within a range of an average value of the total light transmittance of all the samples within ± 1.5%, preferably within a range of ± 1.3%, and further, Preferably, it must be within the range of ± 1.0%. In labels and bags manufactured from film rolls in which the total light transmittance of each sample does not fall within the above range, individual concealment properties fluctuate, and in containers covered with these labels, etc., deterioration of the contents may occur. It is more likely that something that is likely to occur will occur.
[0027]
Next, preferable physical properties of the film wound around the heat-shrinkable polyester film roll of the invention will be described.
[0028]
[Changes in heat shrinkage]
In the film wound around the film roll of the present invention, when the average value of the heat shrinkage in the above-described maximum shrinkage direction is calculated, the heat shrinkage of all the samples is within a range of ± 5% of this average value. It is preferable that it fits.
[0029]
In the long film employed in the present invention, as described above, the heat shrinkage in the maximum shrinkage direction is 20% or more, but the heat shrinkage of all sampled samples is within ± 5% of the average value. If it is within the range, it can be said that the heat shrinkage is uniform over the entire length of the steady region of the film. Therefore, in the case of a label or a bag obtained from such a film, since the fluctuation of the individual heat shrinkage is small, the rejection rate in the step of shrinking the coating on the container or the like is reduced, and the occurrence of defective products is drastically reduced. Can be. The degree of change in the heat shrinkage is more preferably within ± 3% of the average value of the heat shrinkage, and further preferably within ± 2%.
[0030]
Next, the composition of the film wound around the heat-shrinkable polyester film roll of the present invention will be described.
[0031]
[Film composition]
In the present invention, in the heat shrinking step, it has excellent shrink finish in a wide temperature range from low to high temperatures, and in particular, even in a relatively low temperature range, shrinkage spots, wrinkles, and a shrink finish appearance with little distortion can be obtained. In addition, a film made of a polyester resin is used because a beautiful glossiness can be obtained.
[0032]
A known (copolymerized) polyester polycondensed with a polyhydric alcohol component using at least one of aromatic dicarboxylic acids, their ester-forming derivatives, and aliphatic dicarboxylic acids as a polycarboxylic acid component constituting the polyester resin. Can be used. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, and 5-sodium sulfoisophthalic acid. Examples of these 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. In addition, an oxycarboxylic acid such as p-oxybenzoic acid and a polyvalent carboxylic acid such as trimellitic anhydride and pyromellitic anhydride may be used in combination, if necessary.
[0033]
Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, dimer diol, 1,3-propanediol, triethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, and 1,6-hexane. Diol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol, 1,10-decanediol And the like, alkylene oxide adducts of bisphenol compounds or derivatives thereof, trimethylolpropane, glycerin, pentaerythritol, polyoxytetramethylene glycol, polyethylene glycol and the like.
[0034]
Although not polyhydric alcohols, lactones represented by ε-caprolactone may be partially used. Lactones are ring-opened to become units having ester bonds at both ends, and one lactone-derived unit can be considered to be a carboxylic acid component and an alcohol component. Therefore, when lactones are used, the amount of each polyhydric alcohol component is calculated assuming that the amount obtained by adding the unit amount derived from the lactones to the total polyhydric alcohol component amount of the film is 100 mol%. Also, when calculating the amount of each polyvalent carboxylic acid component, it is calculated assuming that the sum of the total amount of the polyvalent carboxylic acid component of the film and the unit amount derived from the lactone is 100 mol%.
[0035]
The polyester resin constituting the film according to the present invention contains at least one of a 1,4-cyclohexanedimethanol component, a neopentyl glycol component, and a 1,4-butanediol component as a polyhydric alcohol component. Is preferred.
[0036]
In the film according to the present invention, a crystalline ethylene terephthalate unit is preferably used as a main component in order to exhibit tear resistance, strength, heat resistance and the like. On the other hand, a unit containing a 1,4-cyclohexanedimethanol component, a neopentyl glycol component, and a 1,4-butanediol component lowers the crystallinity of the film, increases the degree of non-crystallization, and increases the heat shrinkability. It is expressed.
[0037]
In a conventional heat-shrinkable polyester film, when the film reaches a certain temperature while being heated in the heat-shrinking step, the heat-shrinkage rate may become saturated depending on the composition of the polyester constituting the film. In this case, the heat shrinkage does not progress even if the heating is performed at a temperature higher than the temperature, and it is considered that this phenomenon leads to poor finish such as locally generated shrinkage spots and wrinkles. Such a phenomenon tends to occur particularly when heat shrinking is performed in a hot air tunnel having a low thermal conductivity, or when heat shrinking is performed after storing for a long time in an atmosphere of 30 ° C. or more. It is considered that this phenomenon occurs because the molecular chain of the polyester is partially pseudo-crystallized, and the shrinkage rate of the crystallized portion is different from that of the non-crystalline portion.
[0038]
When the above shrinkage whitening occurs, even if the film has a variation in the total light transmittance before the heat shrinkage that satisfies the above-mentioned predetermined range, as a label, when covered and shrunk in a container or the like, the shrinkage whitening portion is a label. Will have a different appearance.
[0039]
However, by introducing a unit containing a 1,4-cyclohexanedimethanol component, a neopentyl glycol component, and a 1,4-butanediol component, which can lower the crystallinity of the film and increase the degree of amorphization, the shrinkage described above is reduced. Whitening can be suppressed. In addition, since the 1,4-butanediol component also has an effect of lowering the glass transition temperature (Tg) of the film, by introducing the same, it is possible to improve the shrink finish of the film in a relatively low temperature range. it can.
[0040]
In terms of suppressing such shrinkage whitening, at least one of the 1,4-cyclohexanedimethanol component, neopentyl glycol component, and 1,4-butanediol component in the polyhydric alcohol component of the film is at least 5 mol%. It is recommended that
[0041]
In the film according to the present invention, it is recommended that Tg is 50 ° C. or higher, more preferably 55 ° C. or higher, 90 ° C. or lower, more preferably 85 ° C. or lower, and further preferably 80 ° C. or lower. When the Tg of the film is within the above range, the shrinkability at a relatively low temperature can be sufficiently ensured, and the natural shrinkage (shrinkage at room temperature) is not too large. Good finish when the coating is shrunk. The Tg of the film can be adjusted by, for example, the ratio of the above-mentioned polyhydric alcohol component or polyhydric carboxylic acid component in the polyester resin.
[0042]
Further, in the case of producing a label from the heat-shrinkable polyester film according to the present invention, for example, the tube processing is performed as described above, but in this case, it is preferable to adhere using a solvent. Examples of the solvent for bonding include aromatic hydrocarbons such as benzene, toluene, xylene and trimethylbenzene; halogenated hydrocarbons such as methylene chloride and chloroform; phenols such as phenol; furans such as tetrahydrofuran; 1,3-dioxolane And organic solvents such as oxolanes. Among them, 1,3-dioxolane is preferable in terms of high safety.
[0043]
Therefore, it is preferable that the heat-shrinkable polyester film of the present invention has adhesiveness by an organic solvent as described above, particularly adhesiveness by 1,3-dioxolane. However, if the crystallinity of the film is high, solvent bonding becomes difficult. Therefore, it is recommended to increase the degree of amorphousness of the film to some extent in order to be able to adhere with the above-mentioned organic solvent, particularly 1,3-dioxolane. Specifically, in 100 mol% of the polyhydric alcohol component, at least one of the 1,4-cyclohexanedimethanol component, neopentylglycol component, and 1,4-butanediol component is 10 mol% or more, preferably 12 mol%. % Is recommended.
[0044]
As an index of the solvent adhesiveness of the film, a solvent adhesive strength measured by a method described later can be cited. In the film according to the present invention, the solvent adhesive strength is preferably 4 N / 15 mm or more. When the solvent adhesive strength of the film is lower than the above lower limit, when the label or the like obtained from the film is coated on a container or the like and contracted, the solvent-adhered portion may be peeled off. The solvent adhesive strength is such that at least one of a 1,4-cyclohexanedimethanol component, a neopentyl glycol component, and a 1,4-butanediol component is introduced into the polyester resin constituting the film to a value equal to or greater than the lower limit. Can be secured.
[0045]
The solvent adhesive strength of the film is determined as follows. In the steady area where the physical properties of the film are stable in the length direction of the film, the film is slit in the length direction, solvent-bonded with 1,3-dioxolane to form a tube, which is crushed flat and wound up Into a tube roll. A tubular sample cut out from this tube roll is cut open to form a film test piece having a width of 15 mm. The film test piece is placed on a tensile tester in which the distance between chucks is set to 20 mm. It is set so as to be positioned, and a tensile test is performed at a temperature of 23 ° C. and a tensile speed of 200 mm / min, and the strength at which the solvent-bonded portion peels off is measured.
[0046]
If the amount of the above-mentioned polyhydric alcohol component is too large, the shrinkage of the film becomes excessively high, and there is a possibility that misalignment of the label and distortion of the design may occur in the heat shrinking step. In addition, the solvent resistance of the film is excessively reduced, and whitening of the film occurs due to the solvent of the ink (such as ethyl acetate) in the printing process, and the tear resistance of the film is unfavorably reduced. Therefore, the total amount of the 1,4-cyclohexanedimethanol component, neopentyl glycol component, and 1,4-butanediol component is preferably 50 mol% or less, and more preferably 45 mol% or less.
[0047]
In addition, in the polyester resin constituting the film according to the present invention, as described above, it is preferable that the ethylene terephthalate unit is a main constituent component. Specifically, 50 mol of the ethylene terephthalate unit is included in 100 mol% of the constituent unit. % Is desirably selected. Therefore, the terephthalic acid component (component formed from terephthalic acid or an ester thereof) is at least 50 mol% in 100 mol% of the polyhydric carboxylic acid component, and the ethylene glycol component is at least 50 mol% in 100 mol% of the polyhydric alcohol component. Is preferable. The ethylene terephthalate unit is more preferably at least 55 mol%, even more preferably at least 60 mol%.
[0048]
The polyester-based resin constituting the film according to the present invention can be produced by melt polymerization according to a conventional method, but the so-called direct polycondensation in which an oligomer obtained by directly reacting a polycarboxylic acid and a polyhydric alcohol is subjected to polycondensation. A so-called transesterification method in which a methyl ester of a polyvalent carboxylic acid and a polyhydric alcohol are subjected to a transesterification reaction and then polycondensed, and the like, may be used, and any production method can be applied. Further, a polyester-based resin obtained by another polymerization method may be used. The introduction of units derived from lactones is, for example, a method of adding a lactone before the above polycondensation to perform polycondensation, a method of copolymerizing a polymer obtained by the above polycondensation with a lactone, or the like. Can be achieved by
[0049]
The polymerization degree of the polyester resin is preferably 0.5 dl / g in terms of intrinsic viscosity, more preferably 0.6 dl / g or more, and further preferably 0.65 dl / g or more. If the intrinsic viscosity of the polyester resin is less than the above lower limit, the crystallinity of the film becomes high and a sufficient heat shrinkage rate may not be obtained, which is not preferable.
[0050]
Polyester has a polymerization catalyst such as antimony oxide, germanium oxide, and titanium compound, as well as magnesium salts such as magnesium acetate and magnesium chloride, calcium acetate, calcium chloride, etc. Ca salt, Mn salt such as manganese acetate and manganese chloride, Zn salt such as zinc chloride and zinc acetate, Co salt such as cobalt chloride and cobalt acetate are each 300 ppm or less (by mass) as metal ions to polyester. , Phosphoric acid or a phosphoric acid ester derivative such as phosphoric acid trimethyl ester and phosphoric acid triethyl ester may be added in an amount of 200 ppm (by mass) or less in terms of phosphorus (P).
[0051]
The timing of adding the metal ions, phosphoric acid and derivatives thereof is not particularly limited, but generally, metal ions are added at the time of raw material preparation, that is, before transesterification or esterification, and phosphoric acids are added before polycondensation reaction. Is preferred.
[0052]
If necessary, an antioxidant, an ultraviolet absorber, a stabilizer, an antistatic agent, a coloring agent, an antibacterial agent, and the like can be added.
[0053]
In the film according to the present invention, inorganic and / or organic fine particles (hereinafter, both of them are simply referred to as “fine particles”) are essential components in order to keep the total light transmittance at or below the upper limit. The light incident on the film scatters and / or absorbs when it hits these fine particles, so that the total light transmittance is reduced.
[0054]
Examples of the inorganic fine particles include various fine particles known as inorganic lubricants. For example, known inert particles such as kaolin, clay, calcium carbonate, silicon oxide, aluminum oxide, titanium oxide, calcium phosphate, and carbon black are suitable. . Fine particles formed inside the polyester resin at the time of the synthesis from a metal compound catalyst used at the time of the synthesis of the polyester resin, such as an alkali metal compound or an alkaline earth metal compound, may be used. Examples of the organic fine particles include fine particles of a high melting point organic compound which is insoluble at the melt extrusion temperature of the polyester resin, and an infusible polymer having a crosslinked structure.
[0055]
The content of these fine particles is, for example, preferably from 0.1 to 20% by mass, more preferably from 0.5 to 10% by mass, based on the total mass of the film. If the content of the fine particles is below the above range, it may be difficult to make the total light transmittance equal to or less than the above upper limit. On the other hand, when the content of the fine particles exceeds the above range, the film strength tends to decrease, and the film formation tends to be difficult. In the case of the fine particles derived from the metal compound catalyst used in the synthesis of the polyester-based resin, the amount is extremely small, and therefore can be ignored when determining the amount of the fine particles in the film.
[0056]
The average particle diameter of the fine particles contained in the film is preferably from 0.001 to 3.5 μm as measured by a Coulter counter method. More preferably, it is 0.05 to 1 μm. When the average particle size is below the above range, it may be difficult to make the total light transmittance equal to or less than the upper limit. On the other hand, when the average particle size exceeds the above range, the cavities generated due to the presence of the fine particles become large. When the amount or size of the cavity increases, the cavity itself has transparency, so the transparency of the film is rather improved, and it may be difficult to reduce the total light transmittance to the above upper limit or less. is there.
[0057]
In the present invention, when the total light transmittance of the film is set to be equal to or less than the above upper limit, if the film is achieved using only the fine particles, the film strength may be reduced. Therefore, the film according to the present invention preferably contains cavities (fine cavities). Like the fine particles, the cavities can also contribute to a reduction in the total light transmittance by scattering light incident on the film. Therefore, if the total light transmittance of the film is set to be equal to or less than the upper limit by both the cavity and the fine particles, it is easy to avoid unnecessary decrease in the strength of the film.
[0058]
In forming the cavities, for example, a method in which a known foaming agent is mixed with the above-mentioned polyester-based resin and melt-extruded can be adopted. However, in the polyester-based resin, a thermoplastic resin incompatible with the polyester-based resin ( Hereinafter, it is preferable to employ a method of mixing and melt-extruding a mixture into a film shape, and stretching the film in at least one direction. In the latter case, the melt-extruded film has a form in which the incompatible resin domains are finely dispersed in the polyester resin matrix, and by stretching this, the fine particles are formed at the polyester resin / incompatible resin interface. A cavity is formed.
[0059]
The incompatible resin is not particularly limited as long as it is a thermoplastic resin incompatible with the polyester resin. Specifically, polystyrene resin, polyolefin resin (polyester, polypropylene, polymethylpentene, etc.), polyacrylic resin [poly (methyl) acrylate, poly (meth) acrylic acid, etc.), polycarbonate resin, polysulfone Resin, cellulose resin and the like. Among them, polystyrene-based resins and polyolefin-based resins are preferred because of their excellent cavity-forming ability.
[0060]
Polystyrene-based resin refers to a thermoplastic resin containing a polystyrene structure as a basic component, and includes a homopolymer such as atactic polystyrene, syndiotactic polystyrene, or isotactic polystyrene, or a component other than styrene grafted or block-formed. It includes a modified polystyrene resin obtained by polymerization or the like, for example, impact-resistant polystyrene (HIPS) or modified polyphenylene ether resin, and a blend of a thermoplastic resin (such as polyphenylene ether) having compatibility with these polystyrene resins.
[0061]
The amount of the incompatible resin to be used is preferably 1 to 20 parts by mass, more preferably 5 to 15 parts by mass, based on 100 parts by mass of the polyester resin. If the amount of the incompatible resin is less than the above range, it may be difficult to make the total light transmittance equal to or less than the upper limit. On the other hand, if the amount of the immiscible resin exceeds the above range, the number of cavities may be too large, and on the contrary, it may be difficult to reduce the total light transmittance below the upper limit.
[0062]
In the film according to the present invention, a layer containing less cavities therein (the above surface layer, hereinafter referred to as “A layer”) and a layer containing more cavities than the A layer (hereinafter referred to as “B layer”). It is also preferable to adopt a laminated structure formed on at least one side of the above. By forming the A layer having a low void content, the roughness of the film surface can be reduced, and thus, if the A layer side is used as the printing surface, it is possible to prevent the aesthetic appearance of printing from being impaired. Further, by forming the layer A having a small void content, it is possible to suppress a decrease in the stiffness (rigidity) of the entire film and improve the mountability to a container or the like.
[0063]
When the film of the present invention has a laminated structure of the layer A and the layer B, the composition of the resin constituting the layer B is 1 to 20 parts by mass of the incompatible resin with respect to 100 parts by mass of the polyester resin. (Preferably 5 to 10 parts by mass), and the amount of the incompatible resin contained in the layer A is smaller than the amount of the incompatible resin contained in the layer B. (A configuration in which the void content of the A layer is smaller than that of the B layer). In order to more effectively exert the above-mentioned effect by the formation of the A layer, it is desirable that the A layer does not substantially contain a cavity. In this case, for example, it is recommended not to use an incompatible resin for the layer A.
[0064]
When the film of the present invention has a layered structure of A layer / B layer, the thickness ratio of A layer and B layer is preferably A layer / B layer = 20/80 to 50/50. When the thickness ratio of the B layer is less than the above range, the concealing property is reduced. For example, when a label using this film is coated on a container and shrunk, the contents of the container can be seen through, or ultraviolet rays can be applied. This is not preferable because the contents may deteriorate due to insufficient shielding properties. On the other hand, when the thickness ratio of the layer A is less than the above range, the effect provided by the layer A may not be sufficiently secured.
[0065]
When the film has a layered structure of layer A / layer B, it is preferable that the amount of fine particles contained in each layer is also different. Specifically, the amount of fine particles in layer B is 0.1 to 20% by mass relative to the total amount of the film. % (More preferably 0.5 to 10% by mass), and the amount of fine particles contained in the A layer is desirably smaller than that in the B layer. In addition, from the viewpoint of more effectively exhibiting the above-described effects of the formation of the A layer, the A layer preferably does not substantially contain fine particles. On the other hand, in order to ensure the slipperiness of the film during film production, the A layer is preferably used. Contains a small amount of fine particles as a lubricant (for example, preferably 0.06% by mass or more, preferably 0.2% by mass or less, more preferably 0.1% by mass or less based on the total amount of the A layer). Is also recommended.
[0066]
Further, it is also desirable that the layer B be an intermediate layer and the layer A be formed on both surfaces. Among the above-mentioned incompatible resins used as a cavity developing agent, for example, in the case of a polystyrene-based resin or the like, smoke is easily generated at the time of melt extrusion of a film, which may cause deterioration in operation in a film manufacturing process. However, if the film according to the present invention has a layered structure of layer A / layer B / layer A, the layer B containing more incompatible resin becomes an intermediate layer, so that the above-mentioned smoking is suppressed, and a long-term effect is obtained. Stable production of is possible. In the case of the layered structure of the layer A / layer B / layer A, the preferable composition and the fine particle content of the resin constituting the layer A and the layer B are the same as in the case of the layered film of the layer A / B. It is. Further, it is desirable that the thickness ratio of each layer of layer A / layer B / layer A is 25/50/25 to 10/80/10. When the thickness ratio of the B layer is less than the above range, the concealing property is reduced. For example, when a label using this film is coated on a container and shrunk, the contents of the container can be seen through, or ultraviolet rays can be applied. This is not preferable because the contents may deteriorate due to insufficient shielding properties. On the other hand, when the thickness ratio of the layer A is less than the above range, the effect provided by the layer A may not be sufficiently secured.
[0067]
Next, a preferred production method for obtaining the heat-shrinkable polyester film roll of the present invention will be described.
[0068]
In producing the film roll of the present invention, [I] controlling the fluctuation of the film composition, [II] controlling the preheating conditions before stretching the film, and [III] film surface in the film stretching step It is important to suppress the temperature fluctuations. By adopting such a manufacturing method, it is possible to make the total light transmittance of the film equal to or less than the upper limit value and to control the fluctuation of the total light transmittance within the above range. Further, other physical properties described above can be ensured.
[0069]
[Suppression of fluctuation in film composition]
Generally, as described above, a heat-shrinkable polyester film is prepared by blending two or more kinds of polymers having different types and compositions or using a plurality of copolymerized monomer components from the viewpoint of achieving both heat shrinkage characteristics and strength. Thus, a method has been adopted in which other constituent units other than the main constituent units are introduced into the raw material polymer to change the characteristics of the obtained film. Here, as a method of incorporating other constituent units into the film, there are a method of performing copolymerization and using the copolymer alone, and a method of blending different types of homopolymers or copolymers.
[0070]
In the system using the copolymer alone, the composition hardly changes in the long film wound around the film roll.
[0071]
On the other hand, the blending method is widely used industrially because the physical properties of the film can be easily changed only by changing the blend ratio, and the film can be used for industrial production of various kinds of films. In addition, in the film according to the present invention, it is preferable to form fine voids in the film using the incompatible resin, but in this case, the film is made of a blend of a polyester resin and an incompatible resin. Will be configured. In addition, it has been found that in the case of such a polymer blend, the composition fluctuation and physical property fluctuation of the film wound around one roll are likely to be large. Therefore, in the case of the blending method, it is preferable to use the following method.
[0072]
(A) Uniform chip shape
In the blending method, usually, a plurality of raw polyester resin chips and incompatible resin chips having different compositions are blended in a hopper, then melt-kneaded and extruded from an extruder to form a film. For example, when there are three types of polymer chips (polyester resin chips and incompatible resin chips) as raw materials, the respective polymer chips are supplied continuously or intermittently to three hoppers, and a buffer hopper is provided as necessary. Finally, while mixing three types of polymer chips in the hopper immediately before or immediately above the extruder (referred to as “final hopper” for convenience), the raw material chips are quantitatively extruded in accordance with the extrusion amount of the extruder. To form a film.
[0073]
However, depending on the capacity or shape of the final hopper, when the amount of chips in the final hopper is large and when the remaining amount is small, the composition of the chips supplied from the final hopper to the extruder differs, so that raw material segregation occurs. It has been found by the present inventors that the above phenomenon occurs. This problem is particularly prominent when the shapes or specific gravities of the various polymer chips are different. As a result, the content of the 1,4-cyclohexanedimethanol component, neopentyl glycol component, 1,4-butanediol component and the like in the long film fluctuates.
[0074]
In order to obtain a film with a small variation in the content of such components, as a means of reducing the variation in the composition of the polymer constituting the film, the shape of the plural types of polymer chips to be used is adjusted and the raw material segregation in the final hopper is performed. It is preferable to suppress this phenomenon.
[0075]
The raw material chips of the polyester resin are usually taken out of the polymerization apparatus in the form of strands in a molten state after polymerization, immediately cooled with water, and then cut with a strand cutter. For this reason, the polyester resin chip usually has an elliptical column shape with an elliptical cross section. In the case of an incompatible resin, the shape obtained by the polymerization method is different, but after polymerization, it is possible to use an extruder or the like to use an extruder or the like to obtain an elliptic columnar chip having an elliptical cross section in the same manner as in the case of the polyester resin. it can. At this time, as the other polymer chips to be mixed with the most used polymer chip, the average major axis (mm), the average minor axis (mm), and the average chip length of the cross-sectional ellipse of the material tip of the most used polymer are used. (Mm), it was found that the above-mentioned segregation of the raw materials could be reduced by using the ones within the range of ± 20%. It is more preferable to use those having an average value within a range of ± 15%.
[0076]
If there is a difference in the size of the chips, when the mixture of chips falls in the final hopper, the smaller chips are more likely to fall first. For this reason, when the remaining amount of chips in the final hopper decreases, the ratio of large chips increases, which causes the raw material segregation. However, by using chips within the above range, segregation of these raw materials can be reduced, and a long film having a uniform composition can be obtained.
[0077]
Even if homopolyesters having different compositions are used, or a homopolyester and a copolymerized polyester are blended and used, for example, whitening of a film due to poor compatibility or fluctuation of the total light transmittance due to the whitening. No problems occur. This is because the raw polyester is considerably heated in the melt-kneading process in the extruder described below, so that a transesterification reaction occurs between the respective polyesters, and when extruded from the extruder, a copolymer having a similar composition is obtained. This is because the polyester mixture tends to be modified. This can be confirmed from the fact that only one peak showing the Tg of the film is observed except for the peak based on the incompatible resin.
[0078]
Further, for example, when the film according to the present invention contains the above-mentioned incompatible resin, the change in the fine particle content is more than the change in the incompatible resin content in the film, and It has been found by the present inventors that the influence on the fluctuation of the light transmittance is very large. Therefore, in manufacturing the film roll of the present invention, it is more important to suppress the fluctuation of the fine particle content in the film. On the other hand, with respect to the incompatible resin, it is possible to suppress the fluctuation of the total light transmittance of the film even if the chip shape is somewhat away from the above range.
[0079]
In order to suppress the change in the content of the fine particles in the film, it is preferable to adopt a method in which at least a part of the raw material polymer chips contains the total amount of the fine particles of the film in advance. In order to include the fine particles in at least a part of the raw material polymer chips, for example, a method of kneading the raw material polymer and the fine particles using an extruder or the like in advance to obtain a raw material chip in which the fine particles are uniformly dispersed can be adopted. . If the shape of the fine particle-dispersed raw material chips is adjusted to be within the above range, the segregation of the raw material chips, that is, the segregation of the fine particles can be suppressed, so that the fluctuation of the fine particle content of the film is reduced. It can be suppressed. The chip containing the fine particles in advance may be a polyester resin chip or an incompatible resin chip.
[0080]
(B) Optimization of hopper shape
The above-mentioned optimization of the final hopper shape is also a preferable means for obtaining a long film having a uniform composition. In other words, by using a funnel-shaped hopper as the final hopper and setting its inclination angle to 65 ° or more, a large chip can be easily dropped like a small chip, and the upper end of the content descends while maintaining a horizontal plane. This is effective in reducing raw material segregation. As described above, for the immiscible resin, the influence on the change in the total light transmittance of the film is relatively small even if the chip shape is somewhat away from the range of the above (a). Adoption is effective in suppressing composition fluctuation (content fluctuation) when a chip whose tip shape is slightly away from the above range is used. A more preferable inclination angle is 70 ° or more. Note that the inclination angle of the hopper is an angle between a funnel-shaped oblique side and a horizontal line segment. A plurality of hoppers may be used upstream of the final hopper, and in this case, the inclination angle of any of the hoppers may be 65 ° or more, more preferably 70 ° or more.
[0081]
(C) Optimization of hopper capacity
As a means for reducing the raw material segregation in the hopper, it is also preferable to optimize the capacity of the hopper to be used. Here, the appropriate capacity of the hopper is in the range of 15 to 120% by mass of the discharge amount per hour of the extruder. If the capacity of about 15% by mass or more of this discharge amount is not in the hopper, it is difficult to supply the raw material stably, and if the hopper is too large, the raw material chip mixture will remain in the hopper for a long time. The possibility of chip segregation is the reason for setting the hopper capacity within the above range. The hopper capacity is more preferably in the range of 20 to 100% by mass of the discharge amount per hour of the extruder. The method (c) is also effective in suppressing composition fluctuation (content fluctuation) in the film when a chip whose chip shape does not satisfy the range of the above (a) is used.
[0082]
(D) Reduction of fine powder
Reducing the ratio of fine powder generated due to scraping of the raw material chips used is also a preferable means for suppressing the fluctuation of the film composition. Since the fine powder promotes the occurrence of raw material segregation, it is preferable to remove the fine powder generated in the process and reduce the ratio of the fine powder contained in the hopper. The ratio of the fine powder to be contained is preferably controlled within 1% by mass, and more preferably within 0.5% by mass, throughout the entire process until the raw material chips enter the extruder. Specifically, the fine powder may be removed by a method of passing through a sieve at the time of chip formation with a strand cutter, or a method of passing through a cyclone air filter when feeding the raw material chips by air.
[0083]
In order to make the composition of the long film uniform, any of the above (a) to (d) may be adopted. It is more preferable to employ two or more of these four means, and it is even more preferable to employ all of (a) to (d).
[0084]
[Control of preheating conditions before stretching]
The heat-shrinkable polyester film according to the present invention is manufactured by melt-extruding a raw material polymer into a film shape and stretching it (described later). When stretching in the transverse direction using a tenter or the like, it is preferable to perform preheating before the stretching step. However, during this preheating step, if the heat transfer to the film is insufficient and the inside of the film does not reach a temperature suitable for stretching, microvoids are generated inside the film in the stretching step described below, and the film is whitened. I do. If the long film is partially whitened due to this cause, the total light transmittance fluctuates. Further, as described above, when the film has a layered structure such as layer A / layer B or layer A / layer B / layer A, the void content is small, and layer A, which is responsible for ensuring the gloss of the film, is also used. However, whitening may occur due to the above reasons, and the effect of forming the A layer may not be secured.
[0085]
When preheating the film using a normal stretching device such as a tenter, the inside of the film can be brought to a temperature suitable for stretching by controlling the speed and temperature of hot air for heating. Specifically, the blowing speed of the hot air is set to 12 m / sec or more, preferably 13 m / sec or more, and the difference (T1) between the temperature T1 (° C) of the hot air and the surface temperature T2 (° C) of the film before the preheating is performed. -T2) is set at 40 ° C. or more and 90 ° C. or less, preferably 45 ° C. or more and 85 ° C. or less, and hot air is applied to the upper surface and the lower surface of the film, so that the film surface temperature becomes a temperature within a range of Tg + 0 ° C. to Tg + 60 ° C. Heat until heated. In the ordinary apparatus, the hot air is normally applied perpendicular to the film surface, but may be applied obliquely to the film surface.
[0086]
By adopting the above preheating conditions, the generation of microvoids in the stretching step can be suppressed, and the fluctuation of the total light transmittance of the film can be controlled within the above-mentioned predetermined range.
[0087]
In the above preheating step, when the blowing speed of hot air or “T1−T2” is less than the above range, heat transfer to the film is insufficient, and the temperature inside the film cannot be adjusted to a temperature suitable for stretching. There are cases. On the other hand, when “T1−T2” exceeds the above range, the surface temperature of the film may be excessively increased, and on the contrary, the physical properties of the film may be reduced or the thickness may be uneven.
[0088]
Further, if the blowing speed of the hot air is too high, unevenness in the thickness of the film is likely to occur, so that the hot air speed is desirably 16 m / sec or less.
[0089]
Note that the blowing speed and temperature of the hot air can be controlled by a normal stretching apparatus, and may be adjusted by a control system provided in the apparatus. The surface temperature of the film can be continuously measured in the running direction of the film using, for example, an infrared non-contact surface thermometer.
[0090]
[Uniformization of film surface temperature in stretching process]
Factors that change the physical properties of a long film include a process change when the film is stretched. That is, in order to reduce the fluctuation of the physical properties of the long film, it is preferable to suppress the fluctuation of the temperature in the step of stretching the film and to reduce the fluctuation width of the surface temperature of the film as much as possible.
[0091]
In the case of a polyester film, when uniaxially stretching in the transverse direction using a tenter, there are a preheating step before stretching, a stretching step, a heat treatment step after stretching, a relaxation treatment, a re-stretching treatment step, and the like. In particular, in each of the preheating step, the stretching step, and the heat treatment step after the stretching, the fluctuation range of the surface temperature of the film measured at an arbitrary point is preferably within an average temperature of ± 1 ° C., and is preferably within an average temperature of ± 0 ° C. It is more preferable that the temperature be within 0.5C.
[0092]
Particularly, temperature fluctuations in the preheating step, the stretching step, and the heat treatment step after the stretching greatly affect the fluctuations in the heat shrinkage. Therefore, if the variation in the surface temperature of the film in these steps is small, the film is stretched or heat-treated at the same temperature over the entire length of the film, and the concealing properties and the heat shrinkage behavior of the film are made uniform. Of course, it is preferable that the fluctuation range of the surface temperature of the film is small also in the relaxation process and the re-stretching process.
[0093]
In order to reduce the fluctuation of the film surface temperature, for example, a wind speed fluctuation suppression equipment equipped with an inverter to control the wind speed of the hot air for heating the film is used, or the heat source is 500 kPa or less (5 kgf / cm ² It is preferable to use equipment capable of suppressing temperature fluctuations of hot air using low-pressure steam described below.
[0094]
The fluctuation width of the surface temperature of the film measured at an arbitrary point is, for example, when 2 m has passed since the start of the stretching step, during film production, the film surface temperature is continuously measured, for example, the infrared non-contact surface temperature. The range of fluctuation when measured with a meter. When the production of one roll of film is completed, the average temperature can be calculated. If the fluctuation width of the film surface temperature is within the average temperature ± 1 ° C, the film is stretched under the same conditions over the entire length of the steady region of the film. Therefore, fluctuations in the concealing property, the heat shrinkage behavior, and the like are reduced.
[0095]
Next, a specific example of producing a polyester film will be described.
[0096]
[Production example of polyester film]
The raw material polymer chips (polyester resin chips or incompatible resin chips) controlled to a size satisfying the above means (a) are dried using a drier such as a hopper drier or a paddle drier, or a vacuum drier. And extruded into a film at a temperature of 200 to 300 ° C. using an extruder. Alternatively, the undried polymer material chips are similarly extruded into a film while removing moisture in a vented extruder. In addition, at least a part of the raw material polymer chip contains inorganic and / or organic fine particles in advance.
[0097]
For the extrusion, any existing method such as a T-die method and a tubular method may be employed. When the film has a laminated structure such as the above-mentioned A layer / B layer or A layer / B layer / A layer, a raw material for forming each layer is put into another extruder. Melt and knead, for example, before the T-die or inside the T-die, the resin is bonded in a molten state. After the extrusion, the unstretched film is obtained by cooling (quenching) with a casting roll. At the time of this cooling, it is preferable to use a so-called electrostatic application adhesion method in that an unstretched film with less unevenness in thickness can be obtained. The “unstretched film” includes a film to which a tension necessary for feeding the film has been applied.
[0098]
Next, a stretching process is performed on the unstretched film. Since it is practical from the viewpoint of production efficiency that the maximum shrinkage direction is the transverse (width) direction of the film, an example of the stretching method in the case where the maximum shrinkage direction is the transverse direction is shown here. When the maximum contraction direction is the longitudinal (longitudinal) direction of the film, the film can be stretched according to a normal operation such as changing the stretching direction by 90 ° in the following method.
[0099]
In the preliminary heating step before the stretching step, the blowing speed and temperature of the hot air for heating are controlled as described above.
[0100]
The stretching in the transverse direction is performed at a predetermined temperature within the range of Tg-20 ° C to Tg + 40 ° C, by 2.0 to 10.0 times, preferably 2.5 to 6.0 times. Thereafter, heat treatment is performed at a predetermined temperature in the range of 60 ° C to 110 ° C, and further heat treatment is performed as necessary at a predetermined temperature in the range of 40 ° C to 100 ° C to obtain a heat-shrinkable polyester film. The above heat treatment is usually carried out under a fixed tension, but it is also possible to simultaneously relax or broaden by 20% or less. An existing method such as a method of bringing the film into contact with a heating roll or a method of gripping the film with a clip in a stretched tenter can be used for the heat treatment. In the transverse stretching step, as described above, it is recommended to use equipment capable of reducing the fluctuation of the film surface temperature.
[0101]
In addition, as a stretching method, not only a uniaxial stretching in a tenter but also a stretching of 1.0 to 4.0 times, preferably 1.1 to 2.0 times in a longitudinal direction may be performed. . When biaxial stretching is performed as described above, it is possible to stretch at a relatively high magnification in one of the vertical and horizontal directions and to reduce the other stretching magnification as much as possible. When performing biaxial stretching, any of sequential biaxial stretching and simultaneous biaxial stretching may be performed, and re-stretching may be performed as necessary. In the sequential biaxial stretching, the stretching order may be any of vertical, horizontal, vertical, horizontal, vertical, horizontal, vertical, and horizontal. Even in the case of employing these longitudinal stretching steps or biaxial stretching steps, it is preferable to minimize fluctuations in the film surface temperature in the preheating step, the stretching step, and the like, similarly to the transverse stretching. For example, in performing longitudinal stretching, two or more rolls having different rotation speeds arranged in parallel can be used, and the film can be stretched by utilizing the speed difference between the rolls. In stretching the film, only this longitudinal stretching may be performed.
[0102]
When the film contains the above-mentioned incompatible resin, fine voids are formed at the polyester resin / incompatible resin interface in the above-mentioned stretching step.
[0103]
Focusing on suppressing the internal heat generation of the film due to stretching and reducing the film temperature unevenness in the width direction, the heat transfer coefficient of the stretching step is 0.00377 J / cm. ² · Sec · ° C (0.0009 calories / cm ² · Sec · ° C) or more. 0.00544-0.00837 J / cm ² · Sec · ° C (0.0013 to 0.0020 calories / cm ² .Sec. ° C.) is more preferable.
[0104]
Also, during the above stretching process, before stretching, or after stretching, one or both surfaces of the film are subjected to various surface treatments, and the film has an antistatic property, a lubricity, a light shielding property, an adhesion to a container or the like, a release property, etc. Can be improved. Examples of such a surface treatment include a corona discharge treatment and a treatment for applying various surface treatment agents.
[0105]
[Others]
The heat-shrinkable polyester film roll in the invention is preferably a heat-shrinkable film having a width of 0.2 m or more and a length of 300 m or more wound around a winding core (core). Film rolls having a width of less than 0.2 m are of low industrial value, and film rolls having a length of less than 300 m have a small winding length of the film. Since the fluctuation of the total light transmittance becomes small, the effect of the present invention is hardly exhibited. The width of the film roll is preferably 0.3 m or more, more preferably 0.4 m or more. Further, the length of the film wound around the roll is more preferably 400 m or more, and further preferably 500 m or more.
[0106]
The upper limits of the width and the length of the film roll are not particularly limited, but in general, the width is preferably 1.5 m or less, and the length is preferably 6000 m or less when the film thickness is 45 μm from the viewpoint of easy handling. As the winding core, a plastic core such as 3 inches, 6 inches, or 8 inches, a metal core, or a paper tube can be used.
[0107]
Although the thickness of the film constituting the heat-shrinkable polyester film roll of the present invention is not particularly limited, for example, the heat-shrinkable polyester film for a label is preferably 15 to 300 μm, more preferably 25 to 200 μm.
[0108]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples do not limit the present invention, and include modifications that do not depart from the gist of the present invention. The methods for measuring the physical properties of the chips obtained in the synthesis examples and the films obtained in the examples and comparative examples are as follows.
[0109]
(1) Confirmation of steady area and setting of sample cut-out part
With respect to the film roll around which a film having a length of 1000 m obtained in Examples and Comparative Examples described later was wound, five samples were cut out at intervals of 20 m from the second end (end of winding) of the film, and the first sample of the film was cut out. Five samples were cut out at intervals of 20 m from the portion 200 m inside from the end (winding start portion) toward the first end, and the thermal shrinkage rate (described later) of these samples in the maximum shrinkage direction was measured. The heat shrinkage of each sample was within the range of 20% or less. Moreover, during the production of the film, the production / stretching process was stable. Therefore, it was confirmed that each film roll corresponded to the steady region over the entire length of the film.
[0110]
In each physical property measurement, the first sample cut-out portion was the second end of the film (0 m from the end of winding), and the final sample cut-out portion was the first end of the film (0 m from the start of winding). Samples were collected from a total of 11 sample cut-out portions. In each physical property measurement, unless otherwise specified, ten samples (test pieces) were cut out from each sample cut-out part, and the average values of the physical properties of the ten samples (test pieces) in each sample cut-out part were determined. Were taken as the physical properties of the sample.
[0111]
(2) Polyester chip composition
Each sample was dissolved in a solvent obtained by mixing chloroform D (manufactured by Yurisop) and trifluoroacetic acid D1 (manufactured by Yurisop) at a ratio of 10: 1 (volume ratio) to prepare a sample solution, and NMR (“GEMINI-200”) was prepared. "; Manufactured by Varian Co., Ltd.) under the measurement conditions of a temperature of 23 ° C. and a cumulative number of 64 times. In the NMR measurement, the composition ratio of the components constituting the chip is calculated based on the peak intensity of the proton.
[0112]
(3) Intrinsic viscosity
0.1 g of a raw material chip is precisely weighed, dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane = 3/2 (mass ratio), and measured at 30 ± 0.1 ° C. with an Ostwald viscometer. The intrinsic viscosity [η] is determined by the following equation (Huggins equation).
[0113]
(Equation 1)

[0114]
Where η _sp : Specific viscosity, t ₀ : Fall time of the solvent using the Ostwald viscometer, t: Fall time of the film solution using the Oswald viscometer, C: concentration of the film solution.
[0115]
In the actual measurement, the intrinsic viscosity is calculated by the following approximate expression where k = 0.375 in the Huggins equation.
[0116]
(Equation 2)

[0117]
Where η _r : Relative viscosity.
[0118]
(4) Total light transmittance
From each sample cut-out part in the above (1), three 50 mm × 50 mm square samples were taken along the running direction of the film and the orthogonal direction thereof, and “NDH-2000T” manufactured by Nippon Denshoku Industries Co., Ltd. was collected. And is measured according to JIS K 7136. Table 5 shows the results.
[0119]
In Table 5, the average value (X) is the average value of the total light transmittance (%) of all the measured 11 samples, and the maximum value (Ymax) is the maximum value of the total light transmittance of the 11 samples. The value (Ymin) indicates the minimum total light transmittance of each of the 11 samples, and also indicates the difference from the average value.
[0120]
(5) Heat shrinkage
The film was cut into a square of 10 cm × 10 cm along the running direction and the direction perpendicular to the running direction, immersed in hot water of 85 ° C. ± 0.5 ° C. for 10 seconds under no load, and thermally shrunk. The sample was immersed in water at a temperature of ± 0.5 ° C. for 10 seconds, and then the length of the sample in the vertical and horizontal directions was measured.
Heat shrinkage (%) = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage)
The direction with the largest contraction rate is the maximum contraction direction. Table 5 shows the results.
[0121]
In Table 5, the average value (R) is the average value of all the heat shrinkage rates (%) of the 11 samples measured, and the maximum value (Smax) is the maximum value of the heat shrinkage rates of the 11 samples, and the minimum value (Smax). Smin) shows the minimum heat shrinkage rate among the 11 samples, and also shows the difference from the average value.
[0122]
(6) Solvent adhesive strength
The film is slit in the longitudinal direction, solvent-bonded with 1,3-dioxolane to form a tube, which is crushed flat and wound up to form a tube roll. A tubular sample cut out from this tube roll is cut open to form a 15 mm-wide film-shaped test piece, and this film-shaped test piece is set to a tensile tester ("Tensilon UTL-4L" manufactured by Toyo Seiki Co., Ltd.) in which the distance between chucks is set to 20 mm. ), A tensile test is performed at a temperature of 23 ° C. and a tensile speed of 200 mm / min., So that the solvent-bonded portion is located at the center of the chucks. Is measured. When the measured value is less than 4 N / 15 mm, it is determined to be defective, and the number of sample cutouts from which a defective sample is cut out is counted.
Solvent adhesion failure rate (%) = 100 × A ÷ B
Calculate the defective ratio of solvent adhesion (%) according to the following. In the above equation, A: the number of sample cutouts (pieces) from which a defective sample was cut out, and B: the number of all sample cutouts (pieces). Table 6 shows the results.
[0123]
(7) Shrink finish
A heat-shrinkable polyester film roll wound around a paper tube is stored for 250 hours in an environment controlled at a temperature of 30 ° C. ± 1 ° C. and 85 RH% ± 2%, and is then coated with grass-colored and gold inks manufactured by Toyo Ink Manufacturing Co., Ltd. After two-color printing, the film is slit, and then, using a center seal machine, a tube is formed by solvent bonding with a mixed solvent of 1,3-dioxolane / acetone = 80/20 (mass ratio). Take up in a folded state (flat crushed state). The tube roll is stored in an atmosphere at a temperature of 23 ° C. ± 1 ° C. and a humidity of 65 RH% ± 3% for 24 hours, and then cut into a whole to produce a heat-shrinkable polyester film label. Using a steam tunnel (model: SH-1500-L) manufactured by Fuji Astec Co., Ltd. to a 500 mL PET bottle (a bottle manufactured by Daiwa Seikan Co., Ltd. and used for Ryoya barley tea by Suntory Co., Ltd.) A heat-shrinkable polyester film label is attached, the entire amount of the produced label is allowed to pass under the conditions of a tunnel passage time of 5 seconds and a zone temperature of 80 ° C., and the finish of shrinkage is visually determined. The number of tests shall be 1000. The shrinkage finish was evaluated by visual inspection.Wrinkles, jumping up, those with no observed shrinkage were accepted, those with wrinkles, jumping up, or poor shrinkage were rejected.
Shrinkage finished defective rate = 100 x defective label number / total label number
The defective rate (%) of shrinkage finish is determined according to the following formula. Table 6 shows the results.
[0124]
Synthesis Example 1
In a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser, 100 mol% of dimethyl terephthalate as polycarboxylic acid, 70 mol% of ethylene glycol as polyhydric alcohol, 2 mol% of diethylene glycol, and neopentyl Glycol 28 mol% was charged so that the molar ratio of the polyhydric alcohol was 2.2 times the methyl ester, and 0.05 mol% of zinc acetate (relative to the polyhydric carboxylic acid) was used as a transesterification catalyst. As a polycondensation catalyst, 0.025 mol% of antimony trioxide (based on polyvalent carboxylic acids) was added, and transesterification was carried out while distilling off generated methanol from the system. Thereafter, a polycondensation reaction was performed at 280 ° C. under a reduced pressure of 26.7 Pa to obtain a polyester (a) having an intrinsic viscosity of 0.72 dl / g. After the polymerization, the polyester was taken out of the polymerization apparatus in the form of a strand in a molten state, immediately cooled with water, and then cut with a strand cutter to obtain a polyester chip (a). Further, a slightly smaller chip was prepared by changing the cutting conditions. This was designated as polyester chip (b).
[0125]
Synthesis Example 2
In the same manner as in Synthesis Example 1, polyester chips (c) to (f) having compositions shown in Table 1, sizes shown in Table 2, and intrinsic viscosity were obtained. In addition, about the polyester chip (g) of Table 2, the pre-dried polyester chip (f) and ε-caprolactone were charged into the autoclave described in Synthesis Example 1 at a ratio of 70/30 (mass ratio). It was synthesized by mixing and reacting at 230 ° C. for 2 hours. The polyester chips (c ′) in Table 2 are composed of 50% by mass of polyester chips (c) and titanium oxide (TiO 2). ₂ ) Fine particles ("TA-300" manufactured by Fuji Titanium Co., Ltd.): 50% by mass were continuously and separately supplied to the hoppers directly above the extruder by a fixed-quantity feeder, and mixed in the hoppers. The strand obtained by melt extrusion with an extruder was immediately cooled with water, and then cut with a strand cutter.
[0126]
[Table 1]

[0127]
In Table 1, TPA is a terephthalic acid component, EG is an ethylene glycol component, CHDM is a 1,4-cyclohexanedimethanol component, NPG is a neopentyl glycol component, BD is a 1,4-butanediol component, and DEG is Represents a diethylene glycol component, and the ε-CL unit means a unit derived from ε-caprolactone. In Table 1, the “polyhydric carboxylic acid component” amount refers to the amount in the total amount of 100 mol% of the total polyhydric carboxylic acid component amount in the chip and the unit amount derived from ε-caprolactone as “polyhydric alcohol component”. "Amount" means the amount in the total amount of 100 mol% of the total amount of polyhydric alcohol components in the chip and the units derived from ε-caprolactone, and the amount of “ε-CL units” means the amount of ester units in the chips. (Same as the total polyhydric carboxylic acid component amount or the total polyhydric alcohol component amount) and the unit amount derived from ε-caprolactone in the total amount of 100 mol%.
[0128]
[Table 2]

[0129]
Example 1
The chips obtained in the above synthesis examples were separately pre-dried, and as shown in Table 3, chips (c): 7% by mass, chips (d): 73% by mass, and chips (f), as shown in Table 3. : 20% by mass as a raw material of the layer B, chip (d): 50% by mass, chip (f): 20% by mass, chip (c '): 20% by mass, and a crystalline polystyrene resin (manufactured by Nippon Polystyrene Co., Ltd.) G797N "): 10% by mass.
[0130]
The raw material for the A layer is a single screw extruder for the A layer, and the raw material for the B layer is a single screw extruder for the B layer. The laminate was extruded while being laminated so that the layer A / layer B / layer A = 12.5 μm / 25 μm / 12.5 μm in the later thickness, and rapidly cooled by a chill roll to obtain an unstretched film having a total thickness of 200 μm. In addition, supply of each raw material to the extruder of the A layer and the B layer is performed by a method in which the chips are continuously and separately supplied to the hoppers immediately above the respective extruders by a fixed screw feeder and mixed in these hoppers. Adopted. The hopper has a capacity to accommodate 150 kg of raw material chips, and the discharge rate of each extruder is 450 kg per hour. The inclination angle of the hopper was 70 °.
[0131]
After preheating the unstretched film under the conditions described in Table 4, the film was stretched 4.0 times at 75 ° C. in the transverse direction using a tenter, and then heat-treated at 80 ° C. for 10 seconds to obtain a total thickness of 50 μm (layer A). / B layer / A layer = 12.5 μm / 25 μm / 12.5 μm) was continuously formed over 1000 m or more. The fluctuation range of the film surface temperature when the film is continuously manufactured for 1000 m is in the range of an average temperature of ± 0.8 ° C in the preheating step, an average temperature of ± 0.6 ° C in the stretching step, and an average temperature of ± 0.5 ° C in the heat treatment step. Controlled within. In addition, the surface temperature of the film was measured using an infrared non-contact surface thermometer (the same applies to the following Examples and Comparative Examples). The obtained film was slit into a width of 0.4 m and a length of 1000 m, and wound around a 3-inch paper tube to obtain a heat-shrinkable polyester film roll.
[0132]
Example 2
Except that the raw material composition was changed as shown in Table 3 and the preheating conditions and stretching conditions of the unstretched film were changed as shown in Table 4, the total thickness was 50 μm (A layer / B layer / A layer was wound around which a heat-shrinkable polyester film (A layer = 12.5 μm / 25 μm / 12.5 μm) was wound.
[0133]
That is, the heat-shrinkable polyester film rolls of Examples 1 and 2 employ techniques such as optimizing the shape of the polyester raw material chip including the fine-particle-containing chips, optimizing the hopper shape, and optimizing the hopper capacity. The variation of the composition is reduced over the entire length of the long film. Further, the preheating condition before stretching is controlled so that the temperature up to the inside of the long film reaches a temperature suitable for stretching. Further, at the time of film stretching, in each step of preheating, stretching, and heat treatment, the fluctuation range of the surface temperature of the film is controlled within the range of the average temperature ± 1.0 ° C., and each of the steps is controlled over the entire length of the film. Changes in physical properties are reduced. Tables 5 and 6 show the characteristic values of the films of these film rolls.
[0134]
Comparative Example 1
Except that the method for charging the raw materials into the extruder was changed as described below, the heat of the total thickness was 50 μm (A layer / B layer / A layer = 12.5 μm / 25 μm / 12.5 μm) in the same manner as in Example 1. A film roll around which a shrinkable polyester film was wound was manufactured.
[0135]
With the composition shown in Table 3, the raw material for layer A and the raw material for layer B were mixed in advance, respectively, and preliminarily dried. For each of the A layer and the B layer, four hoppers of the same shape each having 400 kg of raw material chips and a tilt angle of 60 ° are arranged in series, and the dried chip mixture is put in the most upstream hopper, and two hoppers are placed. First, third, and fourth (final hopper) were transferred to the extruder for layer A and the extruder for layer B.
[0136]
Comparative Example 2
Except that the raw material composition was changed as shown in Table 3 and the preheating condition and stretching condition of the unstretched film were changed as shown in Table 4, the total thickness was 50 μm (A layer / B layer / A layer was wound around which a heat-shrinkable polyester film (A layer = 12.5 μm / 25 μm / 12.5 μm) was wound.
[0137]
That is, in the heat-shrinkable polyester film rolls of Comparative Examples 1 and 2, the method of suppressing the occurrence of the raw material segregation is not positively adopted, and the variation in the composition becomes large over the entire length of the long film. This is an example. Tables 5 and 6 show the characteristic values of the films of these film rolls.
[0138]
Comparative Examples 3 and 4
Except that the raw material composition was changed as shown in Table 3 and the preheating conditions and stretching conditions of the unstretched film were changed as shown in Table 4, the total thickness was 50 μm (A layer / B layer / A layer was wound around which a heat-shrinkable polyester film (A layer = 12.5 μm / 25 μm / 12.5 μm) was wound.
[0139]
That is, the heat-shrinkable polyester film rolls of Comparative Examples 3 and 4 employ means for suppressing raw material segregation to reduce the variation in the composition over the entire length of the long film. In each of the steps of preheating, stretching, and heat treatment, the fluctuation range of the surface temperature of the film is controlled within the range of the average temperature ± 1.0 ° C., so that the fluctuation of each physical property is reduced over the entire length of the film. However, this is an example in which the preheating conditions before stretching are inappropriate, and the film is manufactured without controlling the inside of the film to a temperature suitable for stretching. Tables 5 and 6 show the characteristic values of the films of these film rolls.
[0140]
[Table 3]

[0141]
Since “titanium oxide fine particles” in Table 3 are supplied in a form contained in the polyester chip (c ′), the amount is shown in parentheses.
[0142]
[Table 4]

[0143]
[Table 5]

[0144]
[Table 6]

[0145]
As is clear from Tables 5 and 6, the long films wound on the heat-shrinkable polyester film rolls of Examples 1 and 2 have small total light transmittance and suppress the fluctuation over the entire length of the film. Have been. That is, these films have good light-cutting properties and also suppress variations in individual light-cutting properties such as heat-shrinkable labels obtained from these films. Therefore, for example, it is suitable for applications such as coated shrink labels such as containers applied to easily degradable contents.
[0146]
【The invention's effect】
The heat-shrinkable polyester film roll of the present invention has a small variance in the total light transmittance of a long film wound on the film roll. And the incidence of product defects is extremely low. Further, the method for producing a heat-shrinkable polyester film roll of the present invention can easily reduce the fluctuation of the total light transmittance of a long film, and is very useful in industrial production.

Claims (7)

A film roll obtained by winding a heat-shrinkable polyester film containing inorganic and / or organic fine particles, wherein the heat-shrinkable polyester film is
(1) In the steady region where the physical properties of the film are stable in the longitudinal direction of the film, the end on the winding start side of the film is a first end, the end on the winding end side is a second end, and the second end A first sample cut-out portion is provided at a position within 2 m inside the portion, and a final sample cut-out portion is provided at a position within 2 m inside the first end portion, and about every 100 m from the first sample cut-out portion. A sample cut-out portion was provided, and a sample cut into a square of 10 cm × 10 cm from each sample cut-out portion was immersed in hot water of 85 ° C. for 10 seconds and pulled up, and then immersed in water of 25 ° C. for 10 seconds and pulled up. When the heat shrinkage in the maximum shrinkage direction is 20% or more for all the samples,
(2) When the total light transmittance of the sample separately cut out from each sample cutout section was measured, the total light transmittance of all the samples was 40% or less, and when the average value thereof was calculated, A heat-shrinkable polyester film roll characterized in that the total light transmittance falls within a range of ± 1.5% of the average value. The heat-shrinkable polyester film roll according to claim 1, wherein the heat-shrinkable polyester film contains cavities. The heat-shrinkable polyester film roll according to claim 2, wherein the heat-shrinkable polyester film contains a polyester resin and a thermoplastic resin incompatible with the polyester resin as constituent elements. The heat-shrinkable polyester film has a surface layer on at least one surface,
The surface layer has an inorganic and / or organic fine particle content of 0.2% by mass or less (including 0% by mass) with respect to the total amount of the surface layer, and contains substantially no void. 4. The heat-shrinkable polyester film roll according to 2 or 3. The heat-shrinkable polyester film roll according to any one of claims 1 to 4, wherein the heat-shrinkable polyester film has a width of 0.2 m or more and a length of 300 m or more. A method for producing a heat-shrinkable polyester film roll according to any one of claims 1 to 5, comprising a step of melt-extruding a raw material polymer chip,
The entire amount of the inorganic and / or organic fine particles of the heat-shrinkable polyester film wound around the heat-shrinkable polyester film roll is previously contained in at least a part of the raw polymer chips. A method for producing a heat-shrinkable polyester film roll. A method for producing a heat-shrinkable polyester film roll by stretching after once winding a film obtained by cooling after melt extrusion of the raw material polymer or after the cooling,
7. The heat-shrinkable polyester film according to claim 6, wherein the heat-shrinkable polyester film is preheated by applying hot air to the upper and lower surfaces of the film under the following conditions (I) and (II) before stretching. Production method of film roll.
here,
(I) Hot air blowing speed of 12 m / sec or more (II) The temperature of hot air is T1 (° C), and the surface temperature of the film before preheating is T2 (° C)
When
40 ≦ T1−T2 ≦ 90
It is.