JP2012045760A

JP2012045760A - Biaxially-oriented laminated polyester film

Info

Publication number: JP2012045760A
Application number: JP2010188303A
Authority: JP
Inventors: Yoshitaka Tanaka; 良敬田中; Makoto Iida; 真飯田; Takeshi Ishida; 剛石田
Original assignee: Teijin DuPont Films Japan Ltd
Current assignee: Toyobo Film Solutions Ltd
Priority date: 2010-08-25
Filing date: 2010-08-25
Publication date: 2012-03-08
Anticipated expiration: 2030-08-25
Also published as: JP5495326B2

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially-oriented laminated polyester film which is excellent in dimensional stability and can be used as a support for a magnetic recording medium.SOLUTION: The biaxially-oriented laminated polyester film is obtained by laminating a film layer B comprising polyester B having one selected from the group comprising ethyleneterephthalate and ethylene-2,6-naphthalenedicarboxylate as a main repeating unit on at least one face of a film layer A comprising polyester A having trimethylene-2,6-naphthalenedicarboxylate as a main repeating unit. The ratio of Young's modulus in the film formation direction of the biaxially-oriented laminated polyester film to that in the width direction thereof is within the range of 1.6-3.5.

Description

本発明は、環境変化、特に温・湿度変化に対して優れた寸法安定性を発現するポリエステルフィルムに関し、特にデジタルデータなどの高密度記録メディアのベースフィルムに適した二軸配向積層ポリエステルフィルムに関する。 The present invention relates to a polyester film that exhibits excellent dimensional stability against environmental changes, particularly temperature and humidity changes, and more particularly to a biaxially oriented laminated polyester film suitable for a base film for high-density recording media such as digital data.

ポリエステルフィルムは、優れた機械的特性、熱的特性および化学的特性とを有することから、各種用途に用いられており、特に寸法安定に優れることからデジタルビデオ用テープやコンピュータのバックアップ用テープ（以後、データテープという）など磁気記録媒体のベースフィルムとして用いられている。 Polyester film has excellent mechanical properties, thermal properties, and chemical properties, so it is used in various applications. Especially, it has excellent dimensional stability. Used as a base film for magnetic recording media.

このデータテープは、近年記録密度の高密度化が進み、トラックの幅が非常に狭くなってきている。その結果、データテープの走行または保存の間に生じるわずかな熱的・力学的寸法変化や、データを記録する際と読み取る際の温湿度環境の違いにより、データを読み取る磁気ヘッドとトラックの位置とがずれてしまい、データの再生不良を引き起こす問題点が生じてきた。従って、高密度記録に対応するデータテープには、温湿度といった環境変化や走行時にかかる張力などの応力に対して高い寸法安定性が要求されている。特に記録方式がリニア記録方式のデータテープでは、データテープの幅方向により高い寸法安定性が要求されている。 In recent years, the recording density of this data tape has been increased, and the width of the track has become very narrow. As a result, due to slight thermal and mechanical dimensional changes that occur during the running or storage of data tape and the difference in temperature and humidity environment when recording and reading data, This causes a problem that causes data reproduction failure. Therefore, data tapes compatible with high-density recording are required to have high dimensional stability against environmental changes such as temperature and humidity and stresses such as tension applied during running. In particular, in a data tape in which the recording method is a linear recording method, higher dimensional stability is required in the width direction of the data tape.

このような、データテープのベースフィルムに用いるフィルムの素材としては、ポリエチレンテレフタレート（以下、ＰＥＴと称することがある。）やポリエチレン−２，６−ナフタレンジカルボキシレート（以下、ＰＥＮと称することがある。）が用いられてきた。しかし、高密度記録のデータテープに求められる寸法安定性の要求はますます厳しくなっており、それだけでは不十分となってきている。 Such a film material used for the base film of the data tape is sometimes referred to as polyethylene terephthalate (hereinafter sometimes referred to as PET) or polyethylene-2,6-naphthalenedicarboxylate (hereinafter referred to as PEN). .) Have been used. However, the demand for dimensional stability required for high-density recording data tapes is becoming stricter and it is not enough.

一方で、ＰＥＴやＰＥＮのほかに、ポリエステル素材として、ポリトリメチレン−２，６−ナフタレンジカルボキシレート（以下、ＰＴＮと称することがある）が知られている。例えば、特許文献１では、ＰＴＮの配向フィルムを感熱孔版用途に用いることが提案されている。また、特許文献２および３では、ＰＴＮの配向フィルムが良好なガスバリア性および耐光性を持つことが提案されている。しかしながら、これら特許文献１〜３の実施例に具体的に開示されたフィルムを追試してみると、湿度膨張係数が従来のＰＥＴやＰＥＮと同等程度のものでしかなかった。 On the other hand, in addition to PET and PEN, polytrimethylene-2,6-naphthalenedicarboxylate (hereinafter sometimes referred to as PTN) is known as a polyester material. For example, Patent Document 1 proposes to use an oriented film of PTN for heat-sensitive stencil applications. Patent Documents 2 and 3 propose that the oriented film of PTN has good gas barrier properties and light resistance. However, when the films specifically disclosed in the examples of Patent Documents 1 to 3 were reexamined, the humidity expansion coefficient was only comparable to that of conventional PET and PEN.

また、特許文献４では、２，６−ポリトリメチレンナフタレート、２，６−ポリテトラメチレンナフタレート、２，６−ポリペンタメチレンナフタレート、及び２，６−ポリヘキサメチレンナフタレートのいずれかからなるフィルムを磁気記録媒体のベースフィルムに用いることが提案されている。また、その実施例の湿度膨張係数を見ると、幅方向のヤング率が９ＧＰａのＰＥＮを用いた場合が６．８ｐｐｍ／％ＲＨで、幅方向のヤング率を１１ＧＰａまで高めた２，６−ポリテトラメチレンナフタレートや２，６−ポリヘキサメチレンナフタレートを用いた場合が５．９〜６．４ｐｐｍ／％ＲＨとある。そして、ポリエステルフィルムの場合、その方向のヤング率が高いほど、分子鎖がその方向に揃っていて湿度膨張係数が低くなる傾向にあることを勘案すると、特許文献４の実施例からは、同程度のヤング率ならＰＥＮと、そのグリコール成分の炭素数を変更したものとでは湿度膨張係数はほとんど変わらないことが理解される。なお、特許文献４は、具体的に２，６−ポリトリメチレンナフタレートでの確認はされていない。 In Patent Document 4, any one of 2,6-polytrimethylene naphthalate, 2,6-polytetramethylene naphthalate, 2,6-polypentamethylene naphthalate, and 2,6-polyhexamethylene naphthalate is used. It has been proposed to use a film made of the above as a base film of a magnetic recording medium. Further, when the humidity expansion coefficient of the example is seen, it is 6.8 ppm /% RH in the case where PEN having a Young's modulus in the width direction of 9 GPa is used, and 2,6-poly which has increased the Young's modulus in the width direction to 11 GPa. The case where tetramethylene naphthalate or 2,6-polyhexamethylene naphthalate is used is 5.9 to 6.4 ppm /% RH. In the case of a polyester film, considering that the higher the Young's modulus in that direction, the molecular chains are aligned in that direction and the humidity expansion coefficient tends to be lower. It is understood that the coefficient of humidity expansion hardly changes between the PEN and the glycol component whose carbon number is changed. In addition, Patent Document 4 does not specifically confirm 2,6-polytrimethylene naphthalate.

特開２００１−２１３９４７号公報JP 2001-213947 A 特開２００１−０３８８６６号公報Japanese Patent Laid-Open No. 2001-038866 特開２０００−０１７１５９号公報Japanese Patent Laid-Open No. 2000-0117159 特開２００７−２８７３１２号公報JP 2007-287312 A

本発明の課題は、ＰＥＴやＰＥＮからなるフィルムが有する温度変化に対する優れた寸法安定性とヤング率などの機械的特性を具備しつつ、さらに優れた湿度変化に対する寸法安定性をも発現できる、特にデータストレージなどの磁気テープのベースフィルムに適したポリエステルフィルムを提供することにある。 The problem of the present invention is that the film made of PET or PEN has excellent dimensional stability with respect to temperature change and mechanical properties such as Young's modulus, and can also exhibit further excellent dimensional stability against humidity change. An object of the present invention is to provide a polyester film suitable for a magnetic tape base film for data storage or the like.

本発明者らは、上記課題を解決しようと鋭意研究したところ、ＰＥＴやＰＥＮとほとんど湿度膨張係数について変わらないと思われていたポリトリメチレン−２，６−ナフタレンジカルボキシレートを、高度に配向させることで、その方向の湿度膨張係数をＰＥＴやＰＥＮに比べて極めて小さくできることを見出した。 As a result of diligent research to solve the above problems, the present inventors highly oriented polytrimethylene-2,6-naphthalenedicarboxylate, which was thought to be almost the same in terms of humidity expansion coefficient as PET and PEN. As a result, it was found that the humidity expansion coefficient in that direction can be made extremely small compared to PET and PEN.

しかしながら、ＰＴＮのフィルムはＰＥＴやＰＥＮに比べ小さな湿度膨張係数を発現できるものの、ヤング率などが低下しやすく、また温度膨張係数なども非常に大きくなりやすいという問題があった。 However, although the PTN film can express a smaller coefficient of humidity expansion than PET and PEN, there are problems that the Young's modulus and the like are likely to decrease and the temperature coefficient of expansion tends to be very large.

そこで、本発明者らは、ＰＴＮの高度に配向させた方向に極めて小さな湿度膨張係数を発現できる特性を活かしつつ、幅方向および製膜方向のヤング率を向上させるべくさらに研究した結果、エチレンテレフタレートまたはエチレン−２，６−ナフタレンジカルボキシレートを主たる繰り返し単位とするポリエステルと積層し、かつフィルムの製膜方向と幅方向のヤング率の比を極めて大きくすることで、特定の方向に温度膨張係数と湿度膨張係数が小さく、しかも実用上必要な機械的特性を有する二軸配向積層ポリエステルフィルムが得られることを見出し、本発明に到達した。 Accordingly, the present inventors have further studied to improve the Young's modulus in the width direction and the film forming direction while taking advantage of the characteristic that a very small humidity expansion coefficient can be expressed in the highly oriented direction of PTN. As a result, ethylene terephthalate Alternatively, by laminating with a polyester having ethylene-2,6-naphthalenedicarboxylate as the main repeating unit, and increasing the ratio of Young's modulus in the film forming direction and the width direction of the film, the temperature expansion coefficient in a specific direction The present inventors have found that a biaxially oriented laminated polyester film having a low humidity expansion coefficient and practically necessary mechanical properties can be obtained.

かくして本発明によれば、トリメチレン−２，６−ナフタレンジカルボキシレートを主たる繰り返し単位とするポリエステルＡからなるフィルム層Ａと、その少なくとも片面にエチレンテレフタレートおよびエチレン−２，６−ナフタレンジカルボキシレートからなる群より選ばれる１種を主たる繰り返し単位とするポリエステルＢからなるフィルム層Ｂとが積層された積層フィルムであって、フィルムの製膜方向と幅方向のヤング率の比が１．６〜３．５の範囲である二軸配向積層ポリエステルフィルムが提供される。 Thus, according to the present invention, film layer A composed of polyester A having trimethylene-2,6-naphthalenedicarboxylate as the main repeating unit, and ethylene terephthalate and ethylene-2,6-naphthalenedicarboxylate on at least one side thereof. A laminated film in which a film layer B made of polyester B having a main repeating unit selected from the group consisting of the above-mentioned groups is laminated, and the ratio of the Young's modulus in the film forming direction to the width direction is 1.6 to 3 A biaxially oriented laminated polyester film in the range of .5 is provided.

また、本発明によれば、本発明の好ましい態様として、全フィルム層Ａの合計厚みと全フィルム層Ｂの合計厚みの比が、１：５〜５：１の範囲であること、フィルム層Ｂのガラス転移温度（ＴｇＢ）が、フィルム層Ａのガラス転移温度（ＴｇＡ）よりも１０〜３０℃の範囲で高いこと、フィルムの製膜方向と幅方向のいずれかのヤング率が、５〜１３ＧＰａの範囲にあること、フィルムの幅方向のヤング率が５〜１３ＧＰａの範囲にあり、磁気記録媒体のベースフィルムに用いられることのいずれかを具備する二軸配向積層ポリエステルフィルムも提供される。 According to the present invention, as a preferred embodiment of the present invention, the ratio of the total thickness of all film layers A to the total thickness of all film layers B is in the range of 1: 5 to 5: 1, film layer B The glass transition temperature (TgB) of the film is higher in the range of 10 to 30 ° C. than the glass transition temperature (TgA) of the film layer A, and the Young's modulus in either the film forming direction or the width direction of the film is 5 to 13 GPa. There is also provided a biaxially oriented laminated polyester film having any of the following: a film having a Young's modulus in the width direction of 5 to 13 GPa and being used for a base film of a magnetic recording medium.

従来のＰＥＴやＰＥＮからなるフィルムに比べ、温度変化に対する優れた寸法安定性とヤング率などの機械的特性を具備しつつ、さらに目的とする方向により優れた湿度変化に対する寸法安定性を具備させることができる。そのため、データストレージなどの磁気テープのベースフィルムに極めて好適なポリエステルフィルムを提供することができる。 Compared to conventional PET and PEN films, it has excellent dimensional stability against temperature changes and mechanical properties such as Young's modulus, and more excellent dimensional stability against humidity changes in the intended direction. Can do. Therefore, it is possible to provide a polyester film that is extremely suitable for a base film of a magnetic tape such as data storage.

本発明におけるポリエステルＡは、トリメチレン−２，６−ナフタレンジカルボキシレートを主たる繰り返し単位とするポリエステルである。ここでいう「主たる」とは、全繰り返し単位のモル数を基準として、８０モル％以上を意味する。本発明におけるポリエステルＡは、本発明の目的を損なわない範囲で、それ自体公知の共重合成分を共重合しても良い。共重合する場合は、通常全酸成分のモル数を基準として、２０モル％以下、更に１０モル％以下が好ましい。 Polyester A in the present invention is a polyester having trimethylene-2,6-naphthalenedicarboxylate as a main repeating unit. Here, “main” means 80 mol% or more based on the number of moles of all repeating units. Polyester A in the present invention may be copolymerized with a known copolymer component as long as the object of the present invention is not impaired. In the case of copolymerization, it is usually preferably 20 mol% or less, more preferably 10 mol% or less, based on the number of moles of all acid components.

また、本発明におけるフィルム層Ａは、上記ポリエステルＡを主成分とし、本発明の目的を損なわない範囲で、ポリエステルＡのほかに、他の樹脂や機能剤などを、フィルム層Ａの重量を基準として、２０重量％以下、さらに１０重量％以下の範囲で含有させてもよい。特に、磁気記録媒体のベースフィルムに好適に用いられてきたＰＥＮに比べ、ＰＴＮはガラス転移温度（以下Ｔｇと称する場合がある）が低くなりやすいので、例えばポリエーテルイミドなどガラス転移温度を高められるような成分を共重合したり、ブレンドしたりすることは好ましい。ポリエーテルイミドをブレンドする場合は、フィルム層Ａの重量を基準として、０．０５重量％以上２０重量％以下が好ましく、特に０．０５重量％以上１０重量％以下、さらに０．０５重量％以上５重量％以下が特に好ましい。上記上限を超えると非晶性のポリエーテルイミドのために延伸性が著しく低下する。また上記下限以下ではポリエーテルイミドのＴｇを高める効果を十分に発揮できなくなる。 In addition, the film layer A in the present invention is based on the weight of the film layer A, in addition to the polyester A, based on the weight of the film layer A, as long as the polyester A is the main component and does not impair the purpose of the present invention. The content may be 20% by weight or less, and further 10% by weight or less. In particular, compared with PEN that has been suitably used for a base film of a magnetic recording medium, PTN tends to have a low glass transition temperature (hereinafter sometimes referred to as Tg), so that the glass transition temperature such as polyetherimide can be increased. It is preferable to copolymerize or blend such components. When blending polyetherimide, it is preferably 0.05% by weight or more and 20% by weight or less, particularly 0.05% by weight or more and 10% by weight or less, more preferably 0.05% by weight or more, based on the weight of the film layer A. 5% by weight or less is particularly preferable. When the above upper limit is exceeded, stretchability is significantly reduced due to amorphous polyetherimide. Moreover, if it is below the above lower limit, the effect of increasing the Tg of the polyetherimide cannot be sufficiently exhibited.

本発明におけるポリエステルＡの固有粘度（Ｉ．Ｖ．）は、０．５〜１．２ｄｌ／ｇ、さらに０．６〜１．０ｄｌ／ｇ、特に０．６〜０．８ｇｌ／ｇの範囲にあることが好ましい。Ｉ．Ｖ．が下限より下回ると、ＰＴＮのフィルム製膜において結晶化が問題になり、均一な延伸が困難になる。他方、Ｉ．Ｖ．が上限を超えると、高分子鎖の絡み合いにより延伸時の応力が大きすぎて、均一な延伸が困難になる。このような好ましい範囲のＩ．Ｖ．を有するＰＴＮは、溶融重合および固相重合法によるＩ．Ｖ．調整によって合成可能となる。 The intrinsic viscosity (IV) of the polyester A in the present invention is in the range of 0.5 to 1.2 dl / g, more preferably 0.6 to 1.0 dl / g, particularly 0.6 to 0.8 dl / g. Preferably there is. I. V. Is less than the lower limit, crystallization becomes a problem in film formation of PTN, and uniform stretching becomes difficult. On the other hand, I.I. V. When the value exceeds the upper limit, the stress at the time of stretching is too large due to the entanglement of polymer chains, and uniform stretching becomes difficult. Such a preferred range of I.V. V. PTN having I.I. is obtained by melt polymerization and solid state polymerization. V. It can be synthesized by adjustment.

本発明におけるポリエステルＢは、エチレンテレフタレートおよびエチレン−２，６−ナフタレンジカルボキシレートを主たる繰り返し単位とするポリエステルである。ここでいう「主たる」とは、全繰り返し単位のモル数を基準として、８０モル％以上であることが好ましい。本発明におけるポリエステルＢは、本発明の目的を損なわない範囲で、それ自体公知の共重合成分を共重合しても良い。特に、より環境変化に対する寸法安定性を向上させる観点から、国際公開２００８／０９６６１２号パンフレットに記載された６，６’−（エチレンジオキシ）ジ−２−ナフトエ酸成分、６，６’−（トリメチレンジオキシ）ジ−２−ナフトエ酸成分および６，６’−（ブチレンジオキシ）ジ−２−ナフトエ酸成分などを共重合することは好ましい態様である。なお、共重合する場合は、通常全酸成分のモル数を基準として、２０モル％以下、更に１０モル％以下が好ましい。 The polyester B in the present invention is a polyester having ethylene terephthalate and ethylene-2,6-naphthalenedicarboxylate as main repeating units. The term “main” as used herein is preferably 80 mol% or more based on the number of moles of all repeating units. Polyester B in the present invention may be copolymerized with a known copolymer component as long as the object of the present invention is not impaired. In particular, from the viewpoint of improving the dimensional stability against environmental changes, the 6,6 ′-(ethylenedioxy) di-2-naphthoic acid component described in the pamphlet of International Publication No. 2008/096612, 6,6 ′-( Copolymerizing a trimethylenedioxy) di-2-naphthoic acid component and a 6,6 ′-(butylenedioxy) di-2-naphthoic acid component is a preferred embodiment. In the case of copolymerization, it is usually preferably 20 mol% or less, more preferably 10 mol% or less, based on the number of moles of all acid components.

また、本発明におけるフィルム層Ｂは、上記ポリエステルＢを主成分とし、本発明の目的を損なわない範囲で、ポリエステルＢのほかに、他の樹脂やそれ自体公知の機能剤などを、フィルム層Ａの重量を基準として、２０重量％以下、さらに１０重量％以下の範囲で含有させてもよい。特に、後述のＰＴＮを一方向に高度に配向させやすいことから、フィルム層Ｂのガラス転移温度（ＴｇＢ）は、フィルム層Ａのガラス転移温度（ＴｇＡ）よりも高いことが好ましく、例えばポリエーテルイミドなどガラス転移温度を高められるような成分を共重合したり、ブレンドしたりすることは好ましい。ポリエーテルイミドをブレンドする場合は、フィルム層Ｂの重量を基準として、０．０５重量％以上２０重量％以下が好ましく、特に０．０５重量％以上１０重量％以下、さらに０．０５重量％以上５重量％以下が特に好ましい。上記上限を超えると非晶性のポリエーテルイミドのために延伸性が著しく低下する。また上記下限以下ではポリエーテルイミドのＴｇを高める効果を十分に発揮できなくなる。 In addition, the film layer B in the present invention contains the above polyester B as a main component and, in addition to the polyester B, other resins or functional agents known per se are added to the film layer A as long as the object of the present invention is not impaired. May be contained in the range of 20% by weight or less, further 10% by weight or less, based on the weight of In particular, the glass transition temperature (TgB) of the film layer B is preferably higher than the glass transition temperature (TgA) of the film layer A because, for example, the below-described PTN is easily highly oriented in one direction. It is preferable to copolymerize or blend components that can increase the glass transition temperature. When blending polyetherimide, it is preferably 0.05% by weight or more and 20% by weight or less, particularly 0.05% by weight or more and 10% by weight or less, more preferably 0.05% by weight or more, based on the weight of the film layer B. 5% by weight or less is particularly preferable. When the above upper limit is exceeded, stretchability is significantly reduced due to amorphous polyetherimide. Moreover, if it is below the above lower limit, the effect of increasing the Tg of the polyetherimide cannot be sufficiently exhibited.

本発明におけるポリエステルＢの固有粘度（Ｉ．Ｖ．）は、０．５〜１．２ｄｌ／ｇ、さらに０．６〜１．０ｄｌ／ｇ、特に０．６〜０．８ｇｌ／ｇの範囲にあることが好ましい。Ｉ．Ｖ．が下限より下回ると、ポリエステルＢのフィルム製膜において結晶化が問題になり、均一な延伸が困難になる。他方、Ｉ．Ｖ．が上限を超えると、高分子鎖の絡み合いにより延伸時の応力が大きすぎて、均一な延伸が困難になる。このような好ましい範囲のＩ．Ｖ．を有するポリエステルＢは、溶融重合および固相重合法によるＩ．Ｖ．調整によって合成可能となる。 The intrinsic viscosity (IV) of the polyester B in the present invention is in the range of 0.5 to 1.2 dl / g, more preferably 0.6 to 1.0 dl / g, particularly 0.6 to 0.8 dl / g. Preferably there is. I. V. Is less than the lower limit, crystallization becomes a problem in film formation of polyester B, and uniform stretching becomes difficult. On the other hand, I.I. V. When the value exceeds the upper limit, the stress at the time of stretching is too large due to the entanglement of polymer chains, and uniform stretching becomes difficult. Such a preferred range of I.V. V. Polyester B having an I.V. V. It can be synthesized by adjustment.

ところで、本発明の二軸配向積層ポリエステルフィルムは、前述のポリエステルＡからなるフィルム層Ａと、その少なくとも片面に前述のポリエステルＢからなるフィルム層Ｂとを積層し、フィルムの製膜方向と幅方向のヤング率の比を１．６〜３．５という範囲にしたことを特徴とする。すなわち、フィルム層Ａによって湿度膨張係数を低減し、他方フィルム層Ｂによって、ヤング率などの機械的特性の低下と温度膨張係数の増大とを抑制できたものである。また、単純にこれらのフィルム層ＡとＢとを積層しただけでは、両フィルム層のよいところと悪いところとをそれぞれ足し合わせただけでしかないが、さらにフィルムの製膜方向と幅方向のヤング率の比を１．６〜３．５という範囲にすることで、ヤング率の高い方向について、温度膨張係数を低く抑えつつ、湿度膨張係数を小さくできたのである。そのため、ヤング率の比が上記下限未満では、特定の方向に温度膨張係数と湿度膨張係数とをともに小さくすることは困難になり、他方上限を超えると、ヤング率などの機械的特性を両方向に具備させるのが困難になる。好ましいフィルムの製膜方向と幅方向のヤング率の比は、１．８〜３．２、さらに２．０〜３．０の範囲である。 By the way, the biaxially oriented laminated polyester film of the present invention is obtained by laminating the film layer A made of the above-mentioned polyester A and the film layer B made of the above-mentioned polyester B on at least one surface thereof, and the film forming direction and the width direction of the film. The ratio of the Young's modulus is in the range of 1.6 to 3.5. That is, the humidity expansion coefficient is reduced by the film layer A, and the decrease in mechanical properties such as Young's modulus and the increase in the temperature expansion coefficient can be suppressed by the film layer B. In addition, simply laminating these film layers A and B only adds together the good and bad points of both film layers. By setting the ratio of the ratios in the range of 1.6 to 3.5, the humidity expansion coefficient could be reduced while keeping the temperature expansion coefficient low in the direction of higher Young's modulus. Therefore, if the ratio of Young's modulus is less than the above lower limit, it becomes difficult to reduce both the temperature expansion coefficient and the humidity expansion coefficient in a specific direction, while if it exceeds the upper limit, mechanical properties such as Young's modulus are increased in both directions. It becomes difficult to provide. The ratio of the Young's modulus in the film forming direction and the width direction of the preferred film is in the range of 1.8 to 3.2, and more preferably 2.0 to 3.0.

また、具体的なフィルムの製膜方向と幅方向のヤング率としては、ヤング率の高い方向が、その方向の温度膨張係数と湿度膨張係数とを低くしやすい点から、４．０〜１３．０ＧＰａの範囲、さらに６．０〜１２．０ＧＰａの範囲にあることが好ましい。他方、ヤング率の低い方向は、その方向の機械的特性を実用に耐えうるように維持しつつ、それに直交する方向の温度膨張係数と湿度膨張係数とを低くしやすい点から２．０〜８．０ＧＰａ、さらに３．０〜７．０ＧＰａの範囲にあることが好ましい。 Further, as the Young's modulus in the film forming direction and the width direction of the specific film, the direction in which the Young's modulus is high tends to lower the temperature expansion coefficient and the humidity expansion coefficient in that direction, so that 4.0-13. It is preferably in the range of 0 GPa, more preferably in the range of 6.0 to 12.0 GPa. On the other hand, the direction where the Young's modulus is low is 2.0 to 8 from the viewpoint that it is easy to lower the temperature expansion coefficient and the humidity expansion coefficient in the direction perpendicular to the direction while maintaining the mechanical properties in that direction so that it can withstand practical use. It is preferably in the range of 0.0 GPa, more preferably 3.0 to 7.0 GPa.

なお、これらのヤング率の関係は、温度膨張係数や湿度膨張係数が小さくしたい方向が、その用途で求められる方向になるように調整すればよい。例えば、磁気記録媒体のベースフィルム、特に磁気テープのベースフィルムに用いられる場合、フィルムの幅方向がヤング率の高い方向で、そのヤング率が５〜１３ＧＰａの範囲にあることが好ましい。 Note that the relationship between these Young's moduli may be adjusted so that the direction in which the temperature expansion coefficient and the humidity expansion coefficient are desired to be reduced is the direction required for the application. For example, when used for a base film of a magnetic recording medium, particularly a base film of a magnetic tape, it is preferable that the width direction of the film is a direction with a high Young's modulus and the Young's modulus is in the range of 5 to 13 GPa.

また、前述のとおり、フィルム層Ａによって湿度膨張係数を低減し、フィルム層Ｂによってヤング率などの機械的特性を維持することから、全フィルム層Ａの合計厚みと全フィルム層Ｂの合計厚みの比は、１：５〜５：１の範囲であることが好ましい。さらに好ましい全フィルム層Ａの合計厚みと全フィルム層Ｂの合計厚みの比は、１：２〜２：１の範囲である。 Moreover, as described above, the film layer A reduces the humidity expansion coefficient and the film layer B maintains the mechanical properties such as Young's modulus. Therefore, the total thickness of all the film layers A and the total thickness of all the film layers B The ratio is preferably in the range of 1: 5 to 5: 1. A more preferable ratio of the total thickness of all film layers A to the total thickness of all film layers B is in the range of 1: 2 to 2: 1.

ところで、一般的にフィルム面内に極めて高度に分子鎖が配向された方向を存在させることで、フィルムの当該方向における湿度膨張係数を低くできるが、ポリエステルＡはこうした高度に配向された方向において、ポリエステルＢに比べてより湿度膨張係数を極めて小さくでき、驚くべきことに負の湿度膨張係数にすることも可能である。そのため、フィルム層Ｂでヤング率などの機械的特性を維持しつつ、一方向にフィルム層Ａの分子鎖をより高度に配向させることが必要である。そのため、前述のようなヤング率の比の関係を具備させなければならないが、さらにフィルム層Ｂのガラス転移温度Ｂ（ＴｇＢ）は、フィルム層Ａのガラス転移温度（ＴｇＡ）よりも、１０〜５０℃高いことが、よりフィルム層Ａの配向を一方向に高度に配向させやすいことから好ましい。これは、ＴｇＢがＴｇＡよりも高いことで、例えば幅方向にフィルム層Ａをより高度に配向させつつ、製膜方向と幅方向にフィルム層Ｂを配向させようとしたとき、製膜方向の延伸温度を高くしつつ、幅方向の延伸温度を低くするような条件を採用することで、フィルム層Ｂは両方向にある程度配向させつつ、フィルム層Ａは幅方向に優先的に配向するような条件が採用できるからである。他方、フィルム層Ｂのガラス転移温度が上記上限より高い高分子の場合、フィルム層Ａのガラス転移温度との差が大きくなりすぎるため、フィルムを延伸した際にフィルム層Ａの分子鎖が配向しない状態で延伸される現象（流動延伸）が生じてしまう。そのような観点から、好ましいＴｇＢ−ＴｇＡは１５〜４５℃、さらに２０〜４０℃の範囲である。なお、製膜方向にフィルム層Ａをより高度に配向させたい場合は、製膜方向の延伸温度を低くし、幅方向の延伸温度を高くすればよいことは容易に理解されるはずである。 By the way, in general, the presence of a direction in which molecular chains are extremely highly oriented in the plane of the film can reduce the coefficient of humidity expansion in the direction of the film, but polyester A is in such a highly oriented direction. Compared to polyester B, the humidity expansion coefficient can be made extremely small, and surprisingly a negative humidity expansion coefficient can be obtained. Therefore, it is necessary to highly orient the molecular chains of the film layer A in one direction while maintaining the mechanical properties such as Young's modulus in the film layer B. Therefore, the relationship of the Young's modulus ratio as described above must be provided, and the glass transition temperature B (TgB) of the film layer B is 10 to 50 higher than the glass transition temperature (TgA) of the film layer A. A high temperature is preferable because the orientation of the film layer A can be highly oriented in one direction. This is because TgB is higher than TgA. For example, when the film layer B is oriented in the film forming direction and the width direction while the film layer A is more highly oriented in the width direction, the film layer is stretched in the film forming direction. By adopting conditions that increase the temperature and lower the stretching temperature in the width direction, the film layer B is oriented to some extent in both directions while the film layer A is preferentially oriented in the width direction. This is because it can be adopted. On the other hand, in the case of a polymer having a glass transition temperature of the film layer B higher than the above upper limit, the difference from the glass transition temperature of the film layer A becomes too large, so that the molecular chain of the film layer A is not oriented when the film is stretched. A phenomenon of stretching in a state (fluid stretching) occurs. From such a viewpoint, preferable TgB-TgA is in the range of 15 to 45 ° C, and further 20 to 40 ° C. In addition, it should be easily understood that when the film layer A is more highly oriented in the film forming direction, it is only necessary to lower the stretching temperature in the film forming direction and increase the stretching temperature in the width direction.

そのような観点から、フィルム層Ｂはエチレン−２，６−ナフタレンジカルボキシレートを主たる繰り返し単位とするポリエステルか、エチレンテレフタレートを主たる繰り返し単位とするポリエステルにポリエーテルイミドなどガラス転移温度を高くするような成分を共重合またはブレンドしたものが好ましい。 From such a viewpoint, the film layer B is made to increase the glass transition temperature such as polyetherimide to polyester having ethylene-2,6-naphthalenedicarboxylate as the main repeating unit or polyester having ethylene terephthalate as the main repeating unit. Those obtained by copolymerizing or blending various components are preferred.

つぎに、本発明の二軸配向積層ポリエステルフィルムの好ましい態様について、さらに詳述する。
本発明におけるフィルム層Ａは、ＤＳＣで測定したガラス転移温度が、７０℃以上、さらに７５℃以上であることが、耐熱性や寸法安定性の点から好ましい。このようなガラス転移温度は、ガラス転移温度を下げるような成分の割合を制御することで調整できる。なお、通常副生物の少ないホモのＰＴＮであれば、ガラス転移温度は８０℃程度であり、よりガラス転移温度の高いものとするには、前述のようにポリエーテルイミドなど、Ｔｇをあげる目的でそれ自体公知の他の共重合成分を共重合したり、ブレンドしたりしても良い。なお、仮にフィルム層Ａの重量を基準として、２０重量％のポリエーテルイミドをＰＴＮにブレンドすると、動的粘弾性を測定した場合の損失正接において、Ｔｇを約２５％高温にすることが可能である。 Next, a preferred embodiment of the biaxially oriented laminated polyester film of the present invention will be described in detail.
The film layer A in the present invention preferably has a glass transition temperature measured by DSC of 70 ° C. or higher, more preferably 75 ° C. or higher from the viewpoint of heat resistance and dimensional stability. Such a glass transition temperature can be adjusted by controlling the ratio of components that lower the glass transition temperature. In addition, in the case of homo PTN with usually few by-products, the glass transition temperature is about 80 ° C. In order to achieve a higher glass transition temperature, as described above, for the purpose of increasing Tg, such as polyetherimide. Other copolymer components known per se may be copolymerized or blended. If 20 wt% of polyetherimide is blended with PTN based on the weight of film layer A, Tg can be increased by about 25% at the loss tangent when dynamic viscoelasticity is measured. is there.

また、本発明におけるＰＴＮは、ＤＳＣで測定した融点が、１９０〜２３０℃の範囲、さらに１９０〜２２５℃の範囲、特に１９５〜２２５℃の範囲にあることが製膜性の点から好ましい。融点が上記上限を越えると、溶融押出して成形する際に、流動性が劣り、吐出などが不均一化しやすくなるため生産性は悪化する。一方で、上記下限未満になると、製膜性は優れるものの、芳香族ポリエステルの持つ機械的特性などは損なわれやすくなる。 Further, the PTN in the present invention preferably has a melting point measured by DSC in the range of 190 to 230 ° C., more preferably in the range of 190 to 225 ° C., particularly in the range of 195 to 225 ° C. from the viewpoint of film forming property. When the melting point exceeds the above upper limit, when melt extrusion is performed, the fluidity is inferior, and the discharge tends to be non-uniform, so that the productivity is deteriorated. On the other hand, when it is less than the above lower limit, although the film-forming property is excellent, the mechanical properties and the like of the aromatic polyester are easily impaired.

本発明の二軸配向積層ポリエステルフィルムは、フィルム層Ａ（Ａ層）とフィルム層Ｂ（Ｂ層）とを有していればよく、それらをＡ層／Ｂ層として積層した２層フィルム、Ａ（Ｂ）層／Ｂ（Ａ）層／Ａ（Ｂ）層として積層した３層フィルム、Ａ（Ｂ）層／Ｂ（Ａ）層／Ａ（Ｂ）層／Ｂ（Ａ）層として積層した４層フィルム、Ａ（Ｂ）層／Ｂ（Ａ）層／Ａ（Ｂ）層／Ｂ（Ａ）層／Ａ（Ｂ）層／として積層した５層フィルム、さらにそれらの層数を増やした多層フィルムであってもよいし、本発明の効果を損なわない範囲で、他のフィルム層やコーティング層などを積層したものでも良い。例えば、本発明の二軸配向積層ポリエステルフィルムの表面に厚み１〜５０ｎｍの水溶性または水分散性高分子、あるいは溶剤可溶性高分子などからなるコーティング層を積層することは好ましい態様である。特に、本発明の二軸配向積層ポリエステルフィルムは、フィルム層ＡとＢとで、組成の異なるポリエステルを用いており、各層の配向に違いが生じることから、延伸性を高めやすく、また剥離や配向差によるカールを抑えやすいことから、合計のフィルム層の層数が８層以上の多層フィルムであることが好ましく、特に１０〜１０００層、さらに２０〜２００層の多層フィルムであることが好ましい。なお、前述の全フィルム層Ａの合計厚みと全フィルム層Ｂの合計厚みは、このように複数のフィルム層ＡやＢがある場合に、それらの厚みを合計したものである。 The biaxially oriented laminated polyester film of the present invention only needs to have a film layer A (A layer) and a film layer B (B layer), and a two-layer film obtained by laminating them as an A layer / B layer, A (B) 3 layer film laminated as layer / B (A) layer / A (B) layer, 4 laminated as A (B) layer / B (A) layer / A (B) layer / B (A) layer Layer film, 5-layer film laminated as A (B) layer / B (A) layer / A (B) layer / B (A) layer / A (B) layer /, and multilayer film with more layers It is also possible to use a laminate of other film layers, coating layers, etc., as long as the effects of the present invention are not impaired. For example, it is a preferable embodiment to laminate a coating layer made of a water-soluble or water-dispersible polymer having a thickness of 1 to 50 nm or a solvent-soluble polymer on the surface of the biaxially oriented laminated polyester film of the present invention. In particular, the biaxially oriented laminated polyester film of the present invention uses polyesters having different compositions between the film layers A and B, and the orientation of each layer is different. Since it is easy to suppress curl due to the difference, the total number of film layers is preferably a multilayer film having 8 or more layers, particularly a multilayer film having 10 to 1000 layers, more preferably 20 to 200 layers. In addition, the total thickness of all the above-mentioned film layers A and the total thickness of all the film layers B total those thickness, when there exist several film layers A and B in this way.

ところで、本発明の二軸配向積層ポリエステルフィルムは、平滑性と層構成を簡便に調整しやすいことから、表裏で表面粗さが異なる積層構造であることが好ましい。特に、磁気記録媒体の走行耐久性や、磁気ヘッドとの走行性の良化、あるいは、巻き取り性などハンドリング性の向上のため、表面粗さが粗い側の表面を構成するフィルム層は不活性粒子を含有させることが好ましい。なお、本発明でいう不活性粒子とは、無機または有機の粒子で、フィルムを形成するポリマー中で本発明の効果を損なうような化学的反応を起こさないものをいう。また、磁気記録テープのベースフィルムに用いるときは、記録特性を損なうような電磁気的影響を与えないものであることが好ましい。このような不活性粒子としては、それ自体公知のものを好適に使用でき、例えば球状シリカ粒子、球状の架橋ポリスチレン粒子、球状のシリコーン粒子などが好適に挙げられる。 By the way, since the biaxially oriented laminated polyester film of the present invention is easy to adjust the smoothness and the layer structure, it is preferable that the biaxially oriented laminated polyester film has a laminated structure having different surface roughnesses on the front and back sides. In particular, the film layer constituting the surface having a rough surface is inactive to improve the running durability of the magnetic recording medium, the running property with the magnetic head, or the handling property such as the winding property. It is preferable to contain particles. The inert particles referred to in the present invention are inorganic or organic particles that do not cause a chemical reaction that impairs the effects of the present invention in the polymer forming the film. Further, when used for a base film of a magnetic recording tape, it is preferable that it does not give an electromagnetic influence that impairs recording characteristics. As such inert particles, those known per se can be preferably used. For example, spherical silica particles, spherical crosslinked polystyrene particles, spherical silicone particles and the like can be preferably mentioned.

本発明の二軸配向積層ポリエステルフィルムに含有させる不活性粒子の好ましい平均粒径および含有量は、用途やフィルムの積層構造によって異なるが、例えば磁気記録テープのベースフィルムに用いる場合、以下のようなものが好ましい。 The preferred average particle size and content of the inert particles contained in the biaxially oriented laminated polyester film of the present invention vary depending on the use and the laminated structure of the film. For example, when used for a base film of a magnetic recording tape, the following Those are preferred.

まず、磁性層側の表面のフィルム層に含有させる不活性粒子の平均粒径は、０．００５〜０．５μｍが好ましく、より好ましくは、０．０１〜０．３μｍ、さらに好ましくは０．０３〜０．２μｍ、最も好ましくは０．０５〜０．１５μｍである。含有量は、磁性層側の表面のフィルム層の重量を基準として、０．００１〜１重量％が好ましく、より好ましくは０．００５〜０．５重量％、さらに好ましくは０．０１〜０．３重量％、最も好ましくは０．０１〜０．２重量％である。一方、磁性層を形成しない側の表面のフィルム層に含有させる不活性粒子は、２種類以上のサイズの異なる不活性粒子（不活性粒子１と２）を用いることが好ましい。そのため、不活性粒子１の平均粒径は、０．０５〜２μｍが好ましく、より好ましくは、０．１〜１μｍ、さらに好ましくは０．２〜０．６μｍである。また、不活性粒子２の平均粒経は、０．０１〜０．３μｍが好ましく、さらに好ましくは０．０３〜０．２μｍ、最も好ましくは０．０５〜０．１５μｍである。また、不活性粒子１の含有量は、磁性層を形成しない側の表面のフィルム層の重量を基準として、０．００１〜１重量％が好ましく、より好ましくは０．００５〜０．５重量％、さらに好ましくは０．０１〜０．３重量％、最も好ましくは０．０２〜０．２重量％である。また、不活性粒子２の含有量は、磁性層を形成しない側の表面のフィルム層の重量を基準として、０．００１〜１重量％が好ましく、より好ましくは０．００５〜０．５重量％、さらに好ましくは０．０１〜０．３重量％、最も好ましくは０．０２〜０．２重量％である。 First, the average particle diameter of the inert particles contained in the film layer on the magnetic layer side is preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.3 μm, and still more preferably 0.03. It is -0.2 micrometer, Most preferably, it is 0.05-0.15 micrometer. The content is preferably 0.001 to 1% by weight, more preferably 0.005 to 0.5% by weight, and still more preferably 0.01 to 0. 0% by weight based on the weight of the film layer on the surface on the magnetic layer side. 3% by weight, most preferably 0.01-0.2% by weight. On the other hand, it is preferable to use two or more kinds of inert particles (inactive particles 1 and 2) having different sizes as the inert particles to be included in the film layer on the surface on which the magnetic layer is not formed. Therefore, the average particle diameter of the inert particles 1 is preferably 0.05 to 2 μm, more preferably 0.1 to 1 μm, and still more preferably 0.2 to 0.6 μm. The average particle size of the inert particles 2 is preferably 0.01 to 0.3 μm, more preferably 0.03 to 0.2 μm, and most preferably 0.05 to 0.15 μm. Further, the content of the inert particles 1 is preferably 0.001 to 1% by weight, more preferably 0.005 to 0.5% by weight, based on the weight of the film layer on the surface on which the magnetic layer is not formed. More preferably, it is 0.01 to 0.3% by weight, and most preferably 0.02 to 0.2% by weight. Further, the content of the inert particles 2 is preferably 0.001 to 1% by weight, more preferably 0.005 to 0.5% by weight, based on the weight of the film layer on the surface on which the magnetic layer is not formed. More preferably, it is 0.01 to 0.3% by weight, and most preferably 0.02 to 0.2% by weight.

また、本発明の二軸配向積層ポリエステルフィルムは、磁気記録媒体のベースフィルムに用いる場合、磁性層を形成する側の表面にあるフィルム層は、０．５μｍ以上、さらに１．０μｍ以上の厚みを有することが、他のフィルム層に含有される不活性粒子による突き上げによる表面の平坦性低下を抑えやすいことから好ましい。なお、本発明の二軸配向積層フィルムの厚みは、用いる用途に応じて適宜選択すればよく、特に制限されないが、磁気記録媒体のベースフィルムに用いる場合、３〜６μｍ、さらに３．５〜５μｍ、特に４〜４．８μｍの間にあることが好ましい。 When the biaxially oriented laminated polyester film of the present invention is used as a base film of a magnetic recording medium, the film layer on the surface on which the magnetic layer is formed has a thickness of 0.5 μm or more, and further 1.0 μm or more. It is preferable to have it because it is easy to suppress a decrease in surface flatness due to push-up by inert particles contained in other film layers. In addition, the thickness of the biaxially oriented laminated film of the present invention may be appropriately selected according to the use to be used, and is not particularly limited. In particular, it is preferably between 4 and 4.8 μm.

本発明の二軸配向積層ポリエステルフィルムは、本発明の効果を損なわない範囲で、熱安定剤、酸化防止剤、紫外線吸収剤、帯電防止剤、難燃剤、顔料、染料、脂肪酸エステル、ワックスなどの有機滑剤などが添加されていてもよい。 The biaxially oriented laminated polyester film of the present invention is a range that does not impair the effects of the present invention, such as heat stabilizer, antioxidant, ultraviolet absorber, antistatic agent, flame retardant, pigment, dye, fatty acid ester, wax, etc. An organic lubricant or the like may be added.

つづいて、本発明の二軸配向積層ポリエステルフィルムの製膜方法について説明するが、本発明はこの方法に制限されるものではない。
まず、本発明の二軸配向積層ポリエステルフィルムを製造するためのポリエステルＡおよびポリエステルＢは、それ自体公知の方法で製造できる。具体的には、ＰＴＮの場合、２，６−ナフタレンジカルボン酸もしくはその低級アルキルエステルとトリメチレングリコールとを、エステル化反応もしくはエステル交換反応させて、さらに所望の固有粘度になるまで重縮合反応させればよい。この際、エステル化反応、エステル交換反応または重縮合反応の反応速度を高めるために、それ自体公知の触媒を好適に使用でき、固相重合などを用いても良い。 Next, the method for producing a biaxially oriented laminated polyester film of the present invention will be described, but the present invention is not limited to this method.
First, polyester A and polyester B for producing the biaxially oriented laminated polyester film of the present invention can be produced by a method known per se. Specifically, in the case of PTN, 2,6-naphthalenedicarboxylic acid or its lower alkyl ester and trimethylene glycol are subjected to an esterification reaction or a transesterification reaction, and a polycondensation reaction is performed until a desired intrinsic viscosity is obtained. Just do it. In this case, in order to increase the reaction rate of the esterification reaction, transesterification reaction or polycondensation reaction, a catalyst known per se can be suitably used, and solid phase polymerization or the like may be used.

また、本発明の二軸配向積層ポリエステルフィルムを製造するため、ポリエステルＢにＰＥＮを用いた場合、ＰＥＮはそれ自体公知の方法で製造できる。具体的には、２，６−ナフタレンジカルボン酸もしくはその低級アルキルエステルとエチレングリコールとを、エステル化反応もしくはエステル交換反応させて、さらに所望の固有粘度になるまで重縮合反応させればよい。この際、エステル化反応、エステル交換反応または重縮合反応の反応速度を高めるために、それ自体公知の触媒を好適に使用できる。 Further, when PEN is used for polyester B to produce the biaxially oriented laminated polyester film of the present invention, PEN can be produced by a method known per se. Specifically, 2,6-naphthalenedicarboxylic acid or a lower alkyl ester thereof and ethylene glycol may be subjected to an esterification reaction or a transesterification reaction, and a polycondensation reaction is performed until a desired intrinsic viscosity is obtained. In this case, a catalyst known per se can be suitably used in order to increase the reaction rate of the esterification reaction, transesterification reaction or polycondensation reaction.

このようにして得られたポリエステルＡおよびポリエステルＢ、さらに必要に応じてそれらに不活性粒子やポリエーテルイミドなど加え、溶融状態でフィードブロックにてそれらを積層し、ダイからシート状に回転している冷却ドラム上に押出し、未延伸積層シートを作成する。 Polyester A and polyester B obtained in this way, and if necessary, add inert particles, polyetherimide, etc. to them, laminate them in a molten state in a feed block, and rotate from die to sheet Extruded onto a cooling drum, and an unstretched laminated sheet is prepared.

そして、得られた未延伸積層シートを、製膜方向（または幅方向）にフィルム層Ａのガラス転移温度（Ｔｇ）＋２０℃以上からＴｇ＋７０℃以下、さらに好ましくはＴｇ＋５０℃〜Ｔｇ＋７０℃の範囲で、２．０〜４．０倍、さらに好ましくは２．５〜３．５の延伸倍率で延伸を行ない、その後、幅方向（または製膜方向）に、フィルム層ＡのＴｇ＋７０℃を上限とした範囲で、３．０〜７．０倍、さらに好ましくは４．０〜６．０の延伸倍率で延伸を行なえばよい。このような延伸方向によって延伸温度に違いを持たせることで、フィルム層Ａを幅方向（または製膜方向）に配向させることが可能であり、幅方向の湿度膨張係数および高弾性率が奏される。なお、詳細な延伸条件は、実際に目的とする湿度膨張係数およびヤング率が決まれば、それに応じてその方向により高い延伸倍率の条件で延伸をしたり、延伸温度を低くすること、またはそれと直交する方向の延伸倍率を低くしたり、延伸温度を低くするなどして、湿度膨張係数を低くしたり、ヤング率を高めたりといった調整ができる。 And in the film forming direction (or width direction) of the obtained unstretched laminated sheet, the glass transition temperature (Tg) of the film layer A + 20 ° C. to Tg + 70 ° C., more preferably Tg + 50 ° C. to Tg + 70 ° C. Stretching is performed at a stretching ratio of 2.0 to 4.0 times, more preferably 2.5 to 3.5, and then, in the width direction (or film forming direction), a range with the upper limit of Tg + 70 ° C. of the film layer A Thus, stretching may be performed at a stretching ratio of 3.0 to 7.0 times, more preferably 4.0 to 6.0. By making the stretching temperature different depending on the stretching direction, it is possible to orient the film layer A in the width direction (or the film forming direction), and the humidity expansion coefficient and the high elastic modulus in the width direction are exhibited. The In addition, if the specific expansion coefficient and Young's modulus are actually determined, the detailed stretching conditions can be stretched under a condition of a higher stretching ratio in that direction, the stretching temperature can be lowered, or orthogonal to it. It is possible to make adjustments such as lowering the coefficient of humidity expansion and increasing the Young's modulus by lowering the stretching ratio in the direction of stretching or lowering the stretching temperature.

もちろん、本発明の二軸配向積層ポリエステルフィルムは、上述のような延伸工程を経た後、弛緩、定長もしくは緊張化で、熱固定処理を行うことが好ましく、その温度は１６０〜１８０℃の温度で熱固定処理を行うことが、その後の寸法安定性をより高められることから好ましい。 Of course, the biaxially oriented laminated polyester film of the present invention is preferably subjected to heat setting treatment by relaxation, constant length or tension after undergoing the stretching process as described above, and the temperature is 160 to 180 ° C. It is preferable to perform the heat setting process at, since the subsequent dimensional stability can be further improved.

このようにして得られた本発明の二軸配向積層ポリエステルフィルムは、目的とする方向の湿度膨張係数を極めて低いものとすることができ、例えばリニア記録方式のデータテープのベースフィルムに用いれば、磁気ヘッドとの湿度変化による幅方向のトラックの位置がずれる、いわゆるトラックズレによるエラーが極めて低いデータテープとすることができる。 The biaxially oriented laminated polyester film of the present invention thus obtained can have a very low humidity expansion coefficient in the intended direction. For example, when used for a base film of a linear recording data tape, A data tape in which the position of the track in the width direction is shifted due to a change in humidity with the magnetic head, that is, an error due to so-called track deviation is extremely low.

なお、このようなデータテープは、本発明の二軸配向積層ポリエステルフィルムの一方の面に、磁性層を形成するための磁性層用塗液を塗布および乾燥することで製造できる。もちろん、必要に応じて、ベースフィルムと磁性層との間に、磁性層の厚みを薄くするための非磁性層を形成したり、磁性層を形成しない側に、データテープとしたときの走行性を向上させるためのバックコート層を形成したりしても良い。 Such a data tape can be manufactured by applying and drying a magnetic layer coating liquid for forming a magnetic layer on one surface of the biaxially oriented laminated polyester film of the present invention. Of course, if necessary, a non-magnetic layer for reducing the thickness of the magnetic layer is formed between the base film and the magnetic layer, or the running property when a data tape is formed on the side where the magnetic layer is not formed. A back coat layer may be formed to improve the resistance.

次の実施例に基づき、本発明の実施形態を説明する。
＜測定方法＞
（１）固有粘度（Ｉ．Ｖ．）
得られたポリエステルの固有粘度は、３５℃でのオルソクロロフェノールを溶媒として用いて測定した。 Based on the following examples, embodiments of the present invention will be described.
<Measurement method>
(1) Intrinsic viscosity (IV)
The intrinsic viscosity of the obtained polyester was measured using orthochlorophenol at 35 ° C. as a solvent.

（２）ガラス転移温度および融点
ガラス転移温度および融点はＤＳＣ（ＴＡインスツルメンツ株式会社製、商品名：Ｔｈｅｒｍａｌａｎａｌｙｓｔ２１００）により試料量１０ｍｇ、昇温速度２０℃／ｍｉｎで測定した。 (2) Glass transition temperature and melting point The glass transition temperature and melting point were measured by DSC (TA Instruments Co., Ltd., trade name: Thermal analyst 2100) at a sample amount of 10 mg and a heating rate of 20 ° C./min.

（３）ヤング率
得られた配向フィルムを試料巾１０ｍｍ、長さ１５ｃｍで切り取り、チャック間１００ｍｍ、引張速度１０ｍｍ／分、チャート速度５００ｍｍ／分の条件で万能引張試験装置（東洋ボールドウィン製、商品名：テンシロン）にて引っ張る。得られた荷重―伸び曲線の立ち上がり部の接線よりヤング率を計算する。 (3) Young's modulus The obtained oriented film was cut out with a sample width of 10 mm and a length of 15 cm, and a universal tensile testing device (trade name, manufactured by Toyo Baldwin, under the conditions of 100 mm between chucks, 10 mm / min tensile speed, 500 mm / min chart speed) : Tensilon). The Young's modulus is calculated from the tangent of the rising portion of the obtained load-elongation curve.

（４）温度膨張係数（αｔ）
得られた二軸配向フィルムを幅方向が測定方向となるように長さ１２ｍｍ、幅５ｍｍに切り出し、真空理工製ＴＭＡ３０００にセットし、窒素雰囲気下（０％ＲＨ）、６０℃で３０分前処理し、その後室温まで降温させる。その後２５℃から７０℃まで２℃／ｍｉｎで昇温して、各温度でのサンプル長を測定し、次式より温度膨張係数を算出する。なお、測定方向が切り出した試料の長手方向であり、５回測定し、その平均値を用いた。
αｔ＝｛（Ｌ_６０−Ｌ_４０）｝／（Ｌ_４０×△Ｔ）｝＋０．５
ここで、上記式中のＬ_４０は４０℃のときのサンプル長（ｍｍ）、Ｌ_６０は６０℃のときのサンプル長（ｍｍ）、△Ｔは２０（＝６０−４０）℃、０．５は石英ガラスの温度膨張係数（×ｐｐｍ／℃）である。 (4) Temperature expansion coefficient (αt)
The obtained biaxially oriented film was cut into a length of 12 mm and a width of 5 mm so that the width direction would be the measurement direction, set in TMA3000 manufactured by Vacuum Riko, and pretreated at 60 ° C. for 30 minutes in a nitrogen atmosphere (0% RH). Then, the temperature is lowered to room temperature. Thereafter, the temperature is raised from 25 ° C. to 70 ° C. at 2 ° C./min, the sample length at each temperature is measured, and the temperature expansion coefficient is calculated from the following equation. In addition, the measurement direction is the longitudinal direction of the sample cut out, the measurement was performed 5 times, and the average value was used.
αt = {(L ₆₀ −L ₄₀ )} / (L ₄₀ × ΔT)} + 0.5
Here, L ₄₀ in the above formula is the sample length (mm) at 40 ° C., L ₆₀ is the sample length (mm) at 60 ° C., ΔT is 20 (= 60-40) ° C., 0.5 Is the coefficient of thermal expansion (× ppm / ° C.) of quartz glass.

（５）湿度膨張係数（αｈ）
得られた配向フィルムを幅方向が測定方向となるように長さ１２ｍｍ、幅５ｍｍに切り出し、真空理工製ＴＭＡ３０００にセットし、３０℃の窒素雰囲気下で、湿度２０％ＲＨと湿度８０％ＲＨにおけるそれぞれのサンプルの長さを測定し、次式にて湿度膨張係数を算出する。なお、測定方向が切り出した試料の長手方向であり、５回測定し、その平均値をαｈとした。
αｈ＝（Ｌ_８０−Ｌ_２０）／（Ｌ_８０×△Ｈ）
ここで、上記式中のＬ_２０は２０％ＲＨのときのサンプル長（ｍｍ）、Ｌ_８０は８０％ＲＨのときのサンプル長（ｍｍ）、△Ｈ：６０（＝８０−２０）％ＲＨである。 (5) Humidity expansion coefficient (αh)
The obtained oriented film was cut into a length of 12 mm and a width of 5 mm so that the width direction was the measurement direction, set in TMA3000 manufactured by Vacuum Riko, and in a nitrogen atmosphere at 30 ° C., at a humidity of 20% RH and a humidity of 80% RH. The length of each sample is measured, and the humidity expansion coefficient is calculated by the following formula. In addition, the measurement direction is the longitudinal direction of the cut out sample, the measurement was performed 5 times, and the average value was αh.
αh = (L ₈₀ −L ₂₀ ) / (L ₈₀ × ΔH)
Here, L ₂₀ in the above formula is a sample length (mm) when 20% RH, L ₈₀ is a sample length (mm) when 80% RH, ΔH: 60 (= 80-20)% RH is there.

（６）二軸配向積層ポリエステルフィルムおよび各フィルム層の厚み
積層フィルムを層間の空気を排除しながら１０枚重ね、ＪＩＳ規格のＣ２１５１に準拠し、（株）ミツトヨ製ダイヤルゲージＭＤＣ−２５Ｓを用いて、１０枚重ね法にて厚みを測定し、１枚当りのフィルム厚みを計算する。この測定を１０回繰り返して、その平均値を１枚あたりの積層フィルムの全体の厚みとした。
一方、フィルム層（Ａ）およびフィルム層（Ｂ）の厚みは、フィルムの小片をエポキシ樹脂にて固定成形し、ミクロトームにて約６０ｎｍの厚みの超薄切片（フィルムの製膜方向および厚み方向に平行に切断する）を作成する。この超薄切片の試料を透過型電子顕微鏡（日立製作所製Ｈ−８００型）にて観察し、その境界からフィルム層（Ａ）とＢの厚みを求めた。 (6) Biaxially oriented laminated polyester film and thickness of each film layer 10 layers of laminated film are removed while excluding air between layers, and conforming to JIS standard C2151, using a dial gauge MDC-25S manufactured by Mitutoyo Corporation. The thickness is measured by a 10-sheet superposition method, and the film thickness per sheet is calculated. This measurement was repeated 10 times, and the average value was taken as the total thickness of the laminated film per sheet.
On the other hand, the thicknesses of the film layer (A) and the film layer (B) were obtained by fixing a small piece of film with an epoxy resin and using a microtome with an ultrathin slice having a thickness of about 60 nm (in the film forming direction and thickness direction). Cut in parallel). The sample of this ultrathin section was observed with a transmission electron microscope (H-800 type manufactured by Hitachi, Ltd.), and the thicknesses of the film layers (A) and B were determined from the boundary.

（７）不活性粒子の平均粒径
添加する不活性粒子の平均粒径および相対標準偏差は、ＪＩＳＺ８８２３−１に準拠する遠心沈降法で得られる粒度分布から得られる数平均値を平均粒径とした。 (7) Average particle diameter of inert particles The average particle diameter and relative standard deviation of the inert particles to be added are the average particle diameter obtained from the particle size distribution obtained by the centrifugal sedimentation method according to JIS Z8823-1. It was.

［実施例１］
２，６−ナフタレンジカルボン酸ジメチル１００重量部と１，３−プロパンジオール６０重量部およびテトラブチルチタネート０．０８重量部を使用し、エステル交換反応を行った。次いで高真空下で重縮合反応を行ない、固有粘度が０．６２ｄｌ／ｇ、ガラス転移温度が８１℃のポリトリメチレン−２，６−ナフタレンジカルボキシレート（ＰＴＮ−１）を得た。
２，６−ナフタレンジカルボン酸ジメチルとエチレングリコールでエステル交換反応を行ない、次いで高真空下で重縮合反応を行ない、固有粘度が０．６３ｄｌ／ｇ、ガラス転移温度が１１７℃のポリエチレン−２，６−ナフタレンジカルボキシレート（ＰＥＮ−１）を得た。
上記原料を十分乾燥した後、２台の押出機に供給し、ＰＴＮ−１は２６０℃で溶融押出し、ＰＥＮ−１は３００℃で溶融押出して、４９層のフィードブロックで溶融樹脂を積層させたのち、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このとき、ＰＥＮ−１とＰＴＮ−１の流量を、表１に示す厚さ比になるように調整し、ＰＴＮ−１を２４層に、ＰＥＮ−１を２５層にそれぞれ均等に分け、両表面層がＰＥＮ−１からなるフィルム層になるように溶融状態で交互に積層した。この未延伸フィルムを、１１５℃の予熱ロールを通して、延伸温度を１３０℃で製膜方向に２．０倍延伸し、つづいて製膜方向に直交する方向（幅方向に）に延伸温度１３０℃で５．８倍の倍率で逐次二軸延伸をした後、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮとＰＥＮからなる積層配向ポリエステルフィルムを得た。
得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 1]
Transesterification was carried out using 100 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, 60 parts by weight of 1,3-propanediol and 0.08 parts by weight of tetrabutyl titanate. Subsequently, a polycondensation reaction was performed under high vacuum to obtain polytrimethylene-2,6-naphthalenedicarboxylate (PTN-1) having an intrinsic viscosity of 0.62 dl / g and a glass transition temperature of 81 ° C.
Polyester-2,6 having a transesterification reaction with dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol, followed by a polycondensation reaction under high vacuum, an intrinsic viscosity of 0.63 dl / g, and a glass transition temperature of 117 ° C. -Naphthalene dicarboxylate (PEN-1) was obtained.
After sufficiently drying the raw material, it was supplied to two extruders, PTN-1 was melt-extruded at 260 ° C., PEN-1 was melt-extruded at 300 ° C., and the molten resin was laminated with a 49-layer feed block. After that, it was cooled and solidified with a casting drum having a surface temperature of 50 ° C. by using an electrostatic application casting method to produce an unstretched film. At this time, the flow rates of PEN-1 and PTN-1 were adjusted to the thickness ratio shown in Table 1, and PTN-1 was equally divided into 24 layers and PEN-1 was divided into 25 layers. The layers were alternately laminated in a molten state so as to be film layers made of PEN-1. This unstretched film is stretched 2.0 times in the film-forming direction at a stretching temperature of 130 ° C. through a preheating roll at 115 ° C., and subsequently stretched at a temperature of 130 ° C. in the direction perpendicular to the film-forming direction (in the width direction) After sequentially biaxially stretching at a magnification of 5.8 times, it was once cooled and heat-treated at 160 ° C. The stretched biaxially oriented film having a thickness of 10 μm was wound with a winder to obtain a laminated oriented polyester film made of PTN and PEN.
Table 1 shows the properties of the obtained laminated oriented polyester film.

［実施例２］
幅方向の延伸温度を１３０℃から１４０℃に変更し、幅方向の延伸倍率を４．８倍に変更して、厚みを１０μｍになるように調整したほかは、実施例１と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Example 2]
Lamination was performed in the same manner as in Example 1 except that the stretching temperature in the width direction was changed from 130 ° C. to 140 ° C., the stretching ratio in the width direction was changed to 4.8 times, and the thickness was adjusted to 10 μm. An oriented polyester film was obtained.
Table 1 shows the characteristics of the obtained laminated alignment film.

［実施例３］
製膜方向の延伸温度を１３０℃から１４５℃に変更し、幅方向の延伸温度を１３０℃から１３５℃に変更し、製膜方向の延伸倍率を２．０倍から３．０倍、幅方向の延伸倍率５．８倍から４．５倍に変更して、厚みを１０μｍになるように調整したほかは、実施例１と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Example 3]
The stretching temperature in the film forming direction was changed from 130 ° C. to 145 ° C., the stretching temperature in the width direction was changed from 130 ° C. to 135 ° C., and the stretching ratio in the film forming direction was changed from 2.0 times to 3.0 times in the width direction. A laminated oriented polyester film was obtained in the same manner as in Example 1 except that the draw ratio was changed from 5.8 times to 4.5 times and the thickness was adjusted to 10 μm.
Table 1 shows the characteristics of the obtained laminated alignment film.

［実施例４］
幅方向の延伸倍率５．８倍から５．０倍に変更して、厚みを１０μｍになるように調整したほかは、実施例１と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Example 4]
A laminated oriented polyester film was obtained in the same manner as in Example 1 except that the draw ratio in the width direction was changed from 5.8 times to 5.0 times and the thickness was adjusted to 10 μm.
Table 1 shows the characteristics of the obtained laminated alignment film.

［実施例５］
表１に示す厚み比になるようにＰＴＮ−１とＰＥＮ−１の流量を調整し、幅方向の延伸温度を１４０℃、延伸倍率を５．４倍に変更して、厚みを１０μｍになるように調整したほかは、実施例１と同様にして積層配向ポリエステルフィルムを得た。得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 5]
Adjust the flow rate of PTN-1 and PEN-1 to the thickness ratio shown in Table 1, change the stretching temperature in the width direction to 140 ° C., and the stretching ratio to 5.4 times, so that the thickness becomes 10 μm. A laminated oriented polyester film was obtained in the same manner as in Example 1 except that it was adjusted. Table 1 shows the properties of the obtained laminated oriented polyester film.

［実施例６］
表１に示す厚み比になるようにＰＴＮ−１とＰＥＮ−１の流量を調整し、幅方向の延伸温度を１４０℃、延伸倍率を５．３倍に変更して、厚みを１０μｍになるように調整したほかは、実施例１と同様にして積層配向ポリエステルフィルムを得た。 [Example 6]
Adjust the flow rate of PTN-1 and PEN-1 to the thickness ratio shown in Table 1, change the stretching temperature in the width direction to 140 ° C., and the stretching ratio to 5.3 times so that the thickness becomes 10 μm. A laminated oriented polyester film was obtained in the same manner as in Example 1 except that it was adjusted.

［実施例７］
製膜方向の延伸倍率を２．０倍から３．５倍、幅方向の延伸倍率５．３倍から５．８倍に変更して、厚みを１０μｍになるように調整したほかは、実施例６と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Example 7]
Example except that the draw ratio in the film forming direction was changed from 2.0 times to 3.5 times, the draw ratio in the width direction was changed from 5.3 times to 5.8 times, and the thickness was adjusted to 10 μm. In the same manner as in Example 6, a laminated oriented polyester film was obtained.
Table 1 shows the characteristics of the obtained laminated alignment film.

［実施例８］
実施例１で作成したＰＴＮ−１とＰＥＮ−１とを十分乾燥した後、２台の押出機に供給し、ＰＴＮ−１は２６０℃で溶融押出し、ＰＥＮ−１は３００℃で溶融押出して、２層のフィードブロックで溶融樹脂を積層させたのち、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このときＰＥＮ−１とＰＴＮ−１の流量は表１に示す厚み比になるように調整した。この未延伸フィルムを、１１５℃の予熱ロールを通して、延伸温度を１３０℃で製膜方向に２．０倍延伸し、つづいて幅方向に延伸温度１２５℃で５．３倍の倍率で逐次二軸延伸をした後、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮとＰＥＮからなる積層配向ポリエステルフィルムを得た。
得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 8]
PTN-1 and PEN-1 prepared in Example 1 were sufficiently dried and then supplied to two extruders. PTN-1 was melt extruded at 260 ° C, PEN-1 was melt extruded at 300 ° C, After laminating the molten resin with a two-layer feed block, it was cooled and solidified with a casting drum having a surface temperature of 50 ° C. using an electrostatic application casting method to produce an unstretched film. At this time, the flow rates of PEN-1 and PTN-1 were adjusted to the thickness ratio shown in Table 1. This unstretched film is passed through a preheating roll at 115 ° C., stretched 2.0 times in the film forming direction at a stretching temperature of 130 ° C., and successively biaxially stretched in the width direction at a stretching temperature of 125 ° C. at a magnification of 5.3 times After extending | stretching, it once cooled and heat-processed at 160 degreeC. The stretched biaxially oriented film having a thickness of 10 μm was wound with a winder to obtain a laminated oriented polyester film made of PTN and PEN.
Table 1 shows the properties of the obtained laminated oriented polyester film.

［実施例９］
製膜方向の延伸温度を１３０℃から１４０℃に変え、幅方向の延伸倍率５．３倍から５．４倍に変更して、厚みを１０μｍになるように調整したほかは、実施例８と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Example 9]
Except for changing the stretching temperature in the film forming direction from 130 ° C. to 140 ° C., changing the stretching ratio in the width direction from 5.3 times to 5.4 times, and adjusting the thickness to 10 μm, Example 8 and Similarly, a laminated oriented polyester film was obtained.
Table 1 shows the characteristics of the obtained laminated alignment film.

［実施例１０］
製膜方向の延伸温度を１３０℃から１４０℃に変え、幅方向の延伸温度を１２５℃から１５０℃に変更し、延伸倍率５．３倍から５．２倍に変更して、厚みを１０μｍになるように調整したほかは、実施例８と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Example 10]
The stretching temperature in the film forming direction is changed from 130 ° C. to 140 ° C., the stretching temperature in the width direction is changed from 125 ° C. to 150 ° C., the stretching ratio is changed from 5.3 times to 5.2 times, and the thickness is changed to 10 μm. A laminated oriented polyester film was obtained in the same manner as in Example 8, except that the adjustment was made.
Table 1 shows the characteristics of the obtained laminated alignment film.

［実施例１１］
幅方向の延伸温度を１２５℃から１５０℃に変更し、延伸倍率５．３倍から５．４倍に変更して、厚みを１０μｍになるように調整したほかは、実施例８と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Example 11]
The same as in Example 8, except that the stretching temperature in the width direction was changed from 125 ° C. to 150 ° C., the stretching ratio was changed from 5.3 times to 5.4 times, and the thickness was adjusted to 10 μm. A laminated oriented polyester film was obtained.
Table 1 shows the characteristics of the obtained laminated alignment film.

［実施例１２］
実施例１で作成したＰＴＮ−１とＰＥＮ−１とを十分乾燥した後、２台の押出機に供給し、ＰＴＮは２６０℃で溶融押出し、ＰＥＮは３００℃で溶融押出して、３層のフィードブロックで溶融樹脂を積層させたのち、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このときＰＥＮ−１とＰＴＮ−１の流量は、表１に示す厚み比になるように調整し、ＰＴＮ−１からなるフィルム層の両面に同じ厚みのＰＥＮ−１からなるフィルム層が位置するように積層した。この未延伸フィルムを、１１５℃の予熱ロールを通して、延伸温度を１３５℃で製膜方向に２．０倍延伸し、つづいて幅方向に延伸温度１３５℃で６．０倍の倍率で逐次二軸延伸をした後、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮとＰＥＮからなる積層配向ポリエステルフィルムを得た。
得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 12]
PTN-1 and PEN-1 prepared in Example 1 are sufficiently dried and then supplied to two extruders. PTN is melt-extruded at 260 ° C., PEN is melt-extruded at 300 ° C., and three layers are fed. After laminating the molten resin in the block, it was cooled and solidified with a casting drum having a surface temperature of 50 ° C. using an electrostatic application casting method to produce an unstretched film. At this time, the flow rates of PEN-1 and PTN-1 are adjusted so as to have the thickness ratio shown in Table 1, so that the film layer made of PEN-1 having the same thickness is positioned on both sides of the film layer made of PTN-1. Laminated. This unstretched film is passed through a preheating roll at 115 ° C., stretched 2.0 times in the film forming direction at a stretching temperature of 135 ° C., and then continuously biaxially at a stretching temperature of 135 ° C. and a magnification of 6.0 times in the width direction. After extending | stretching, it once cooled and heat-processed at 160 degreeC. The stretched biaxially oriented film having a thickness of 10 μm was wound with a winder to obtain a laminated oriented polyester film made of PTN and PEN.
Table 1 shows the properties of the obtained laminated oriented polyester film.

［実施例１３］
テレフタル酸ジメチルとエチレングリコールでエステル交換反応を行ない、次いで高真空下で重縮合反応を行ない、固有粘度が０．５９ｄｌ／ｇ、ガラス転移温度が７８℃のポリエチレンテレフタレート（ＰＥＴ−１）を得た。
そして、実施例１で作成したＰＴＮ−１と上記ＰＥＴ−１とを十分乾燥した後、２台の押出機に供給し、ＰＴＮ−１は２６０℃で溶融押出し、ＰＥＴ−１は２８０℃で溶融押出して、３層のフィードブロックで溶融樹脂を積層させたのち、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このときＰＥＴ−１とＰＴＮ−１の流量は、表１に示す厚み比となるように調整し、ＰＴＮ−１からなるフィルム層の両面に同じ厚みのＰＥＴ−１からなるフィルム層が位置するように積層した。この未延伸フィルムを、９０℃の予熱ロールを通して、延伸温度を１００℃で製膜方向に２．０倍延伸し、つづいて製膜方向に直交する方向（幅方向に）に延伸温度１１０℃で５．０倍の倍率で逐次二軸延伸をした後、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮとＰＥＴからなる積層配向ポリエステルフィルムを得た。
得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 13]
Transesterification was performed with dimethyl terephthalate and ethylene glycol, followed by polycondensation under high vacuum to obtain polyethylene terephthalate (PET-1) having an intrinsic viscosity of 0.59 dl / g and a glass transition temperature of 78 ° C. .
And after fully drying PTN-1 created in Example 1 and the above PET-1, it is supplied to two extruders, PTN-1 is melt-extruded at 260 ° C., and PET-1 is melted at 280 ° C. After extruding and laminating the molten resin with a three-layer feed block, it was cooled and solidified with a casting drum having a surface temperature of 50 ° C. by using an electrostatic application casting method to produce an unstretched film. At this time, the flow rate of PET-1 and PTN-1 is adjusted so as to be the thickness ratio shown in Table 1, and the film layer made of PET-1 having the same thickness is positioned on both surfaces of the film layer made of PTN-1. Laminated. This unstretched film is stretched 2.0 times in the film forming direction at a stretching temperature of 100 ° C. through a preheating roll of 90 ° C., and subsequently stretched at 110 ° C. in the direction perpendicular to the film forming direction (in the width direction). After sequentially biaxial stretching at a magnification of 5.0 times, it was once cooled and heat-treated at 160 ° C. The stretched biaxially oriented film having a thickness of 10 μm was wound up with a winder to obtain a laminated oriented polyester film made of PTN and PET.
Table 1 shows the properties of the obtained laminated oriented polyester film.

［実施例１４］
実施例１で作成したＰＴＮ−１と実施例１３で作成したＰＥＴ−１とを十分乾燥した後、２台の押出機に供給し、ＰＴＮは２６０℃で溶融押出し、ＰＥＴは２８０℃で溶融押出して、４９層のフィードブロックで溶融樹脂を積層させたのち、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このとき、ＰＥＴ−１とＰＴＮ−１の流量を、表１に示す厚さ比になるように調整し、ＰＴＮ−１を２４層に、ＰＥＴ−１を２５層にそれぞれ均等に分け、両表面層がＰＥＴ−１からなるフィルム層になるように溶融状態で交互に積層した。この未延伸フィルムを、９０℃の予熱ロールを通して、延伸温度を１００℃で製膜方向に３．０倍延伸し、つづいて幅方向に延伸温度１１０℃で５．５倍の倍率で逐次二軸延伸をした後、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮとＰＥＴからなる積層配向ポリエステルフィルムを得た。
得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 14]
PTN-1 prepared in Example 1 and PET-1 prepared in Example 13 were sufficiently dried and then supplied to two extruders. PTN was melt extruded at 260 ° C, and PET was melt extruded at 280 ° C. Then, after laminating the molten resin with 49 layers of feed blocks, it was cooled and solidified with a casting drum having a surface temperature of 50 ° C. by using an electrostatic application casting method to produce an unstretched film. At this time, the flow rates of PET-1 and PTN-1 were adjusted so as to have the thickness ratio shown in Table 1, and PTN-1 was divided into 24 layers and PET-1 was divided into 25 layers. The layers were alternately laminated in a molten state so as to be film layers made of PET-1. This unstretched film is stretched 3.0 times in the film forming direction at a stretching temperature of 100 ° C. through a preheating roll of 90 ° C., and then successively biaxially at a stretching temperature of 110 ° C. and a magnification of 5.5 times in the width direction. After extending | stretching, it once cooled and heat-processed at 160 degreeC. The stretched biaxially oriented film having a thickness of 10 μm was wound up with a winder to obtain a laminated oriented polyester film made of PTN and PET.
Table 1 shows the properties of the obtained laminated oriented polyester film.

［実施例１５］
実施例１３で作成したＰＥＴ−１に、組成物の重量を基準として、５重量％となるようにポリエーテルイミド（ＧＥ社製ウルテム１０１０（ガラス転移温度：２１５℃））をブレンドして、（ＰＥＴ−２）を作成した。
そして、実施例１で作成したＰＴＮ−１と上記ＰＥＴ−２とを十分乾燥した後、２台の押出機に供給し、ＰＴＮ−１は２６０℃で溶融押出し、ＰＥＴ−２は２８０℃で溶融押出して、４９層のフィードブロックで溶融樹脂を積層させたのち、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このとき、ＰＥＴ−２とＰＴＮ−１の流量を、表１に示す厚さ比になるように調整し、ＰＴＮ−１を２４層に、ＰＥＴ−２を２５層にそれぞれ均等に分け、両表面層がＰＥＴ−２からなるフィルム層になるように溶融状態で交互に積層した。この未延伸フィルムを、９０℃の予熱ロールを通して、延伸温度を１００℃で製膜方向に３．０倍延伸し、つづいて幅方向に延伸温度１１０℃で５．５倍の倍率で逐次二軸延伸をした後、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮとＰＥＴ組成物からなる積層配向ポリエステルフィルムを得た。
得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 15]
PET-1 prepared in Example 13 was blended with polyetherimide (GE ULTEM 1010 (glass transition temperature: 215 ° C.)) so as to be 5% by weight based on the weight of the composition. PET-2) was prepared.
And after fully drying PTN-1 created in Example 1 and the above PET-2, it is supplied to two extruders, PTN-1 is melt-extruded at 260 ° C., and PET-2 is melted at 280 ° C. After extruding and laminating the molten resin with a 49-layer feed block, it was cooled and solidified with a casting drum having a surface temperature of 50 ° C. using an electrostatic application casting method to produce an unstretched film. At this time, the flow rates of PET-2 and PTN-1 were adjusted so that the thickness ratio shown in Table 1 was obtained, and PTN-1 was divided into 24 layers and PET-2 was divided into 25 layers. The layers were alternately laminated in a molten state so as to be film layers made of PET-2. This unstretched film is stretched 3.0 times in the film forming direction at a stretching temperature of 100 ° C. through a preheating roll of 90 ° C., and then successively biaxially at a stretching temperature of 110 ° C. and a magnification of 5.5 times in the width direction. After extending | stretching, it once cooled and heat-processed at 160 degreeC. The stretched biaxially oriented film having a thickness of 10 μm was wound up with a winder to obtain a laminated oriented polyester film made of PTN and a PET composition.
Table 1 shows the properties of the obtained laminated oriented polyester film.

［実施例１６］
２，６−ナフタレンジカルボン酸ジメチルと６，６’−（エチレンレンジオキシ）ジ−２−ナフトエ酸ジエチルエステルとエチレングリコールとでエステル交換反応を行ない、次いで高真空下で重縮合反応を行ない、固有粘度が０．６３ｄｌ／ｇの６，６’−（エチレンジオキシ）ジ−２−ナフトエ酸成分を全酸成分の７０モル％となるように共重合したＰＥＮ−２を得た。このＰＥＮ−２をＰＥＮ−１と６，６’−（エチレンジオキシ）ジ−２−ナフトエ酸成分が全酸成分の１５モル％となるようにブレンドして、ガラス転移温度が１１４℃のＰＥＮ−３を作成した。
実施例１で作成したＰＴＮ−１と上記ＰＥＮ−３とを十分乾燥した後、２台の押出機に供給し、ＰＴＮ−１は２６０℃で溶融押出し、ＰＥＮ−３は３００℃で溶融押出して、４９層のフィードブロックで溶融樹脂を積層させたのち、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このとき、ＰＥＮ−３とＰＴＮ−１の流量を、表１に示す厚さ比になるように調整し、ＰＴＮ−１を２４層に、ＰＥＮ−３を２５層にそれぞれ均等に分け、両表面層がＰＥＴ−２からなるフィルム層になるように溶融状態で交互に積層した。この未延伸フィルムを、１１５℃の予熱ロールを通して、延伸温度を１３０℃で製膜方向に２．５倍延伸し、つづいて幅方向に延伸温度１３０℃で６．０倍の倍率で逐次二軸延伸をした後、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮと共重合ＰＥＮからなる積層配向ポリエステルフィルムを得た。
得られた積層配向ポリエステルフィルムの特性を表１に示す。 [Example 16]
Transesterification is performed with dimethyl 2,6-naphthalenedicarboxylate, 6,6 '-(ethylenedioxy) di-2-naphthoic acid diethyl ester and ethylene glycol, followed by a polycondensation reaction under high vacuum. PEN-2 obtained by copolymerizing a 6,6 ′-(ethylenedioxy) di-2-naphthoic acid component having a viscosity of 0.63 dl / g to 70 mol% of the total acid component was obtained. This PEN-2 was blended with PEN-1 so that the 6,6 ′-(ethylenedioxy) di-2-naphthoic acid component was 15 mol% of the total acid component, and the glass transition temperature was 114 ° C. -3 was created.
PTN-1 prepared in Example 1 and the above PEN-3 are sufficiently dried and then supplied to two extruders. PTN-1 is melt-extruded at 260 ° C, and PEN-3 is melt-extruded at 300 ° C. After laminating the molten resin with a 49-layer feed block, it was cooled and solidified with a casting drum having a surface temperature of 50 ° C. using an electrostatic application casting method to produce an unstretched film. At this time, the flow rates of PEN-3 and PTN-1 were adjusted to the thickness ratio shown in Table 1, and PTN-1 was equally divided into 24 layers and PEN-3 was divided into 25 layers. The layers were alternately laminated in a molten state so as to be film layers made of PET-2. This unstretched film is stretched 2.5 times in the film forming direction at a stretching temperature of 130 ° C. through a preheated roll at 115 ° C., and then continuously biaxially at a stretching temperature of 130 ° C. and a magnification of 6.0 times in the width direction. After extending | stretching, it once cooled and heat-processed at 160 degreeC. The stretched biaxially oriented film having a thickness of 10 μm was wound with a winder to obtain a laminated oriented polyester film composed of PTN and copolymerized PEN.
Table 1 shows the properties of the obtained laminated oriented polyester film.

［比較例１］
実施例１で作成したＰＴＮ−１を十分乾燥した後、１台の押出機に供給し、２６０℃で溶融押出し、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このＰＴＮ−１の未延伸の単層フィルムを製膜方向に１１０℃で４．０倍、幅方向に１１０℃で３．０倍延伸して、一旦冷却し、１６０℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＴＮの配向ポリエステルフィルムを得た。
得られた配向フィルムの特性を表１に示す。 [Comparative Example 1]
After sufficiently drying the PTN-1 prepared in Example 1, it is supplied to one extruder, melt-extruded at 260 ° C., and cooled and solidified by a casting drum having a surface temperature of 50 ° C. using an electrostatic application casting method. An unstretched film was produced. This unstretched single layer film of PTN-1 was stretched 4.0 times at 110 ° C. in the film forming direction and 3.0 times at 110 ° C. in the width direction, cooled once, and heat-treated at 160 ° C. The stretched biaxially oriented film having a thickness of 10 μm was wound with a winder to obtain an oriented polyester film of PTN.
The properties of the obtained oriented film are shown in Table 1.

［比較例２］
製膜方向の延伸倍率を２．０倍から３．５倍、幅方向の延伸倍率を５．８倍から４．５倍に変更し、厚みが１０μｍになるように未延伸フィルムの厚みを調整したほかは、実施例１と同様にしてＰＴＮの二軸配向フィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Comparative Example 2]
Change the draw ratio in the film forming direction from 2.0 times to 3.5 times and the width direction draw ratio from 5.8 times to 4.5 times, and adjust the thickness of the unstretched film so that the thickness becomes 10 μm. In the same manner as in Example 1, a biaxially oriented film of PTN was obtained.
Table 1 shows the characteristics of the obtained laminated alignment film.

［比較例３］
製膜方向の延伸温度を１３０℃から１５０℃に変更し、製膜方向の延伸倍率を２．０倍から４．０倍、幅方向の延伸倍率５．４倍から４．８倍に変更して、厚みを１０μｍになるように調整したほかは、実施例８と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Comparative Example 3]
The stretching temperature in the film forming direction was changed from 130 ° C. to 150 ° C., the stretching ratio in the film forming direction was changed from 2.0 times to 4.0 times, and the stretching ratio in the width direction was changed from 5.4 times to 4.8 times. A laminated oriented polyester film was obtained in the same manner as in Example 8, except that the thickness was adjusted to 10 μm.
Table 1 shows the characteristics of the obtained laminated alignment film.

［比較例４］
製膜方向の延伸倍率を２．０倍から３．０倍、幅方向の延伸倍率６．０倍から４．８倍に変更して、厚みを１０μｍになるように調整したほかは、実施例１１と同様にして積層配向ポリエステルフィルムを得た。
得られた積層配向フィルムの特性を表１に示す。 [Comparative Example 4]
Except that the draw ratio in the film forming direction was changed from 2.0 times to 3.0 times, the draw ratio in the width direction was changed from 6.0 times to 4.8 times, and the thickness was adjusted to 10 μm. In the same manner as in Example 11, a laminated oriented polyester film was obtained.
Table 1 shows the characteristics of the obtained laminated alignment film.

［比較例５］
実施例１で作成したＰＥＮ−１を十分乾燥した後、１台の押出機に供給し、３００℃で溶融押出し、静電印加キャスト法を用いて表面温度５０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このＰＥＮ−１の未延伸の単層フィルムを、製膜方向に１５０℃で４．０倍、幅方向に１４５℃で４．０倍延伸して、２００℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＥＮの配向ポリエステルフィルムを得た。
得られた配向フィルムの特性を表１に示す。 [Comparative Example 5]
PEN-1 prepared in Example 1 is sufficiently dried, then supplied to one extruder, melt extruded at 300 ° C., and cooled and solidified with a casting drum having a surface temperature of 50 ° C. using an electrostatic application casting method. An unstretched film was produced. This unstretched single-layer film of PEN-1 was stretched 4.0 times at 150 ° C. in the film forming direction and 4.0 times at 145 ° C. in the width direction, and heat-treated at 200 ° C. The stretched biaxially oriented film having a thickness of 10 μm was wound with a winder to obtain an oriented polyester film of PEN.
The properties of the obtained oriented film are shown in Table 1.

［比較例６］
実施例１３で作成したＰＥＴ−１を十分乾燥した後、１台の押出機に供給し、２８０℃で溶融押出し、静電印加キャスト法を用いて表面温度３０℃のキャスティングドラムにて冷却固化し、未延伸フィルムを作製した。このＰＥＴ−１の未延伸の単層フィルムを、製膜方向に１００℃で４．０倍、幅方向に１２０℃で３．０倍延伸して、２００℃で熱処理を施した。こうして延伸された厚み１０μｍの二軸配向フィルムをワインダーで巻き取り、ＰＥＴの配向ポリエステルフィルムを得た。
得られた配向フィルムの特性を表１に示す。 [Comparative Example 6]
The PET-1 prepared in Example 13 was sufficiently dried, then supplied to one extruder, melt extruded at 280 ° C., and cooled and solidified with a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. An unstretched film was produced. This unstretched single-layer film of PET-1 was stretched 4.0 times at 100 ° C. in the film forming direction and 3.0 times at 120 ° C. in the width direction, and heat-treated at 200 ° C. The stretched biaxially oriented film having a thickness of 10 μm was wound up with a winder to obtain an oriented polyester film of PET.
The properties of the obtained oriented film are shown in Table 1.

上記表１中のＰＴＮ−１はポリトリメチレン−２，６−ナフタレンジカルボキシレート、ＰＥＮ−１はポリエチレン−２，６−ナフタレンジカルボキシレート、ＰＥＴ−１はポリエチレンテレフタレート、ＰＥＴ−２はポリエーテルイミドをブレンドしたポリエチレンテレフタレート、ＰＥＮ−３は６，６’−（アルキレンジオキシ）ジ−２−ナフトエ酸を共重合したＰＥＮ、ＭＤは製膜方向、ＴＤはフィルムの幅方向を表す。 In Table 1, PTN-1 is polytrimethylene-2,6-naphthalene dicarboxylate, PEN-1 is polyethylene-2,6-naphthalene dicarboxylate, PET-1 is polyethylene terephthalate, and PET-2 is polyether. Polyethylene terephthalate blended with imide, PEN-3 represents PEN copolymerized with 6,6 ′-(alkylenedioxy) di-2-naphthoic acid, MD represents the film forming direction, and TD represents the width direction of the film.

本発明の磁気記録媒体支持体は、特にデータストレージ用の高密度記録の磁気テープに好ましく用いられる。 The magnetic recording medium support of the present invention is preferably used for a magnetic tape for high density recording especially for data storage.

Claims

One kind selected from the group consisting of a film layer A composed of polyester A having trimethylene-2,6-naphthalenedicarboxylate as the main repeating unit and ethylene terephthalate and ethylene-2,6-naphthalenedicarboxylate on at least one side thereof. And a film layer B made of polyester B, the main repeating unit of which is laminated, and the ratio of the Young's modulus in the film forming direction to the width direction of the film is in the range of 1.6 to 3.5. A biaxially oriented laminated polyester film characterized by

The biaxially oriented laminated polyester film according to claim 1, wherein the ratio of the total thickness of all film layers A to the total thickness of all film layers B is in the range of 1: 5 to 5: 1.

The biaxially oriented laminated polyester film according to claim 1, wherein the glass transition temperature (TgB) of the film layer B is higher in the range of 10 to 50 ° C. than the glass transition temperature (TgA) of the film layer A.

The biaxially oriented laminated polyester film according to any one of claims 1 to 3, wherein the Young's modulus in either the film forming direction or the width direction of the film is in the range of 5 to 13 GPa.

The biaxially oriented laminated polyester film according to any one of claims 1 to 4, wherein the Young's modulus in the width direction of the film is in the range of 4 to 13 GPa and used for a base film of a magnetic recording medium.