JPH05261806A - Manufacture of polyamide biaxially oriented film - Google Patents

Abstract

PURPOSE:To manufacture a polyamide film with a high flatness capable of sufficiently coping with even the improvement of production speed by the use of a specific method of humidity control. CONSTITUTION:The manufacture of biaxially stretched film is such to that after being subjected to biaxial stretching, the polyamide film is so heat-fixed that the contraction coefficient in a hot water of 100 deg.C is allowed to be 3% or less in both the longitudinal and transverse directions and, after that, while continuously blowing humidified air of temperature of 150 deg.C or lower, the moisture content of the film is controlled within the range of 0.5-2.0%, and the film is wound subsequently, wherein the film is cooled below the dew point of humidified air. Thus, a biaxially stretched polyamide film is obtained which has an excellent flatness, and is not liable to crease when rolled, and also has reduced in the occurrence of curl, slack, wrinkle and the like due to moisture absorption which has been a problem in the after working process, in the past.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、ポリアミド二軸延伸フ
ィルムの製造方法に関し、さらに詳しくはフラット性に
優れたポリアミド二軸延伸フィルムの製造方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyamide biaxially stretched film, and more particularly to a method for producing a polyamide biaxially stretched film having excellent flatness.

【０００２】[0002]

【従来の技術】食品包装後ボイル又はレトルト殺菌可能
な包装材料用に適したポリアミド二軸延伸フィルムを得
る為には、フィルムを延伸後、高度に熱処理し、１００
℃の熱水中の収縮率を３％以下にすることが必要である
が、商品価値を高める為にフラット性の改良も又必要で
ある。2. Description of the Related Art In order to obtain a polyamide biaxially stretched film suitable for a packaging material that can be sterilized by boiling or retort after food packaging, after stretching the film, it is subjected to a high heat treatment,
It is necessary to reduce the shrinkage rate in hot water at ℃ to 3% or less, but it is also necessary to improve the flatness in order to increase the commercial value.

【０００３】ポリアミドフィルムのフラット性を解決す
るため、本願出願人は先に特願平２−２４４６７６号に
於いて、ポリアミドフィルムを二軸延伸した後、１００
℃の熱水中の収縮率がタテ方向、ヨコ方向とも３％以下
になるように熱固定し、１５０℃以下の加湿空気を吹き
付けながら、８０℃／秒以下の速度でフィルムを徐冷す
ると同時にフィルムを調湿し、フィルムの水分率を０．
５〜２．０％にして巻き取る方法を提案した。In order to solve the flatness of the polyamide film, the applicant of the present application has previously disclosed in Japanese Patent Application No. 2-244676 that a polyamide film is biaxially stretched and then 100
Heat-set so that the shrinkage rate in hot water at ℃ is 3% or less in both the vertical and horizontal directions, and while gradually blowing the humidified air at 150 ° C or less, slowly cool the film at a rate of 80 ° C / sec or less. The moisture of the film is adjusted to 0.
A method of winding it to 5 to 2.0% was proposed.

【０００４】しかしながら前記提案の方法はポリアミド
二軸延伸フィルムのフラット性を向上させる方法として
は有効であるものの、ここ数年の生産速度の著しい向上
のため、該方法でフラット性のよいフィルムを得るため
には、必要とする加湿ゾーンの長さが非常に長いものに
なってきた。However, although the above-mentioned method is effective as a method for improving the flatness of a polyamide biaxially stretched film, a film having good flatness is obtained by the method because the production speed has been remarkably improved in the past few years. In order to do so, the required humidification zone length has become very long.

【０００５】[0005]

【発明が解決しようとする課題】すなわち該方法でフィ
ルムを調湿し、フィルムの水分率を２％近くまで上げる
ためには、数秒以上の加湿ゾーンの通過時間が必要であ
る。したがって、たとえば生産速度が向上し１５０ｍ／
分以上になると、十数ｍ以上もの加湿ゾーンが必要とな
り、設備が大がかりなものとなり、設備及び運転コスト
が多くかかるという問題の発生を解決しなければならな
くなった。That is, in order to control the humidity of the film by this method and raise the moisture content of the film to nearly 2%, it takes a few seconds or more to pass through the humidifying zone. Therefore, for example, the production speed is improved to 150 m /
If it is more than a minute, a humidification zone of more than ten meters or more is required, the equipment becomes large-scale, and it is necessary to solve the problem that the equipment and the operating cost are high.

【０００６】ポリアミドフィルムは、熱感受性が大きい
こと、雰囲気湿度の影響を受け易いことなど、水分の影
響が加わると、十分に熱固定したとしても、その後の冷
却工程、巻取り工程の湿度によりフラット性が変化す
る。[0006] Polyamide film has a high heat sensitivity and is easily affected by atmospheric humidity, and therefore, even if it is sufficiently heat-fixed, it is flat due to the humidity in the subsequent cooling process and winding process. Sex changes.

【０００７】二軸延伸されたポリアミドフィルムの吸湿
による寸法変化を調べたところ、寸法変化はエネルギー
的な挙動、すなわち膨潤による伸びとエントロピー的な
挙動、すなわち吸湿による構造変化が生じ延伸前の状態
に戻ろうとする傾向（吸湿による縮み）の合成されたも
のであることが判った。前者は可逆的であり、後者は不
可逆的変化である。When the dimension change due to moisture absorption of the biaxially stretched polyamide film was investigated, it was found that the dimension change was in an energetic behavior, that is, elongation due to swelling and entropy behavior, that is, structural change due to moisture absorption occurred before the stretching. It was found that the tendency to return (shrinkage due to moisture absorption) was synthesized. The former is reversible and the latter is irreversible.

【０００８】延伸後強く熱固定（熱処理）したフィル
ム、たとえば高温熱固定後、弛緩熱処理したフィルム、
具体的には１００℃の熱水に浸漬したときの収縮率がタ
テ方向、ヨコ方向とも３％以下になるようなフィルム
は、吸湿による伸びがそのまま現れる。また吸湿伸びは
方向性を持ち、配向軸に沿った方向で大きくなる傾向を
持つ。そのため、延伸時のボーイング現象等によりフィ
ルム巾方向に主配向方向が変化するようなフィルムで
は、フィルム巾方向に吸湿伸びの量と方向が異なるた
め、延伸フィルムのフラット性は低下する。A film which has been strongly heat-set (heat-treated) after stretching, for example, a film which has been heat-set at high temperature and then heat-treated for relaxation,
Specifically, a film having a shrinkage ratio of 3% or less in both the vertical direction and the horizontal direction when immersed in hot water at 100 ° C. shows elongation as it is due to moisture absorption. The hygroscopic elongation has a directional property and tends to increase in the direction along the orientation axis. Therefore, in a film in which the main orientation direction changes in the width direction of the film due to a bowing phenomenon during stretching, the amount and direction of hygroscopic elongation differ in the width direction of the film, and the flatness of the stretched film decreases.

【０００９】そこで本発明は、より効果的な調湿方法を
用いることにより、昨今の生産速度の向上にも充分対応
できるフラット性の良いポリアミドフィルムの製造方法
を提供することを目的とする。Therefore, an object of the present invention is to provide a method for producing a polyamide film having a good flatness, which can sufficiently cope with the recent improvement in production rate by using a more effective humidity control method.

【００１０】[0010]

【課題を解決するための手段】本発明者らはこのような
課題を解決するために鋭意検討した結果、本発明に到達
した。すなわち本発明は、ポリアミドフィルムを二軸延
伸した後、１００℃の熱水中の収縮率がタテ方向、ヨコ
方向とも３％以下になるように熱固定し、その後連続的
に温度１５０℃以下の加湿空気を吹きつけながらフィル
ムの水分率を０．５〜２．０％の範囲に調湿してフィル
ムを巻き取るポリアミド二軸延伸フィルムの製造方法に
おいて、加湿空気を吹き付ける前にフィルムを該加湿空
気の露点以下に冷却することを特徴とするポリアミド二
軸延伸フィルムの製造方法である。The present inventors have arrived at the present invention as a result of intensive studies to solve such problems. That is, according to the present invention, after the polyamide film is biaxially stretched, it is heat-set so that the shrinkage in hot water at 100 ° C is 3% or less in both the vertical and horizontal directions, and then continuously at a temperature of 150 ° C or less. In a method for producing a polyamide biaxially stretched film, wherein a moisture content of a film is adjusted to a range of 0.5 to 2.0% while being blown with humidified air, and the film is wound. A method for producing a polyamide biaxially stretched film, which comprises cooling to below the dew point of air.

【００１１】ポリアミド二軸延伸フィルムは、同時二軸
延伸法、逐次二軸延伸法で製造することが知られてい
る。本発明はその何れの方法で製造されたフィルムにも
適用可能であるが、好ましくは延伸後の熱固定とその後
の冷却をクリップでフィルムの両端を把持して行う方法
に対して本発明を適用することができる。It is known that a polyamide biaxially stretched film is produced by a simultaneous biaxial stretching method and a sequential biaxial stretching method. The present invention is applicable to a film produced by any of the methods, but preferably the present invention is applied to a method of holding both ends of the film with clips for heat setting after stretching and subsequent cooling. can do.

【００１２】さらに、熱固定部または冷却部の一部の工
程で弛緩を伴う処理（以下「弛緩熱処理」とも称す）を
行うことにより、本発明の効果は大きくなる。弛緩を伴
う熱処理とは、相対するクリップ間隔（ヨコ方向、Ｔ
Ｄ）または流れ方向（タテ方向、ＭＤ）のクリップピッ
チを最大延伸倍率より少し戻し、フィルムを緊張状態か
ら緩めながら熱処理する方法である。弛緩熱処理操作に
より熱処理温度をそれほど高くせずに延伸フィルムの熱
水収縮率を低下させることができるため、熱処理時にフ
ィルムが白化したり強度低下したりすることを防ぐこと
ができる。設備的に簡単なヨコ方向の弛緩処理だけでも
効果があるが、タテ方向およびヨコ方向の両軸の弛緩処
理を伴う場合に、本発明は一層有用なものとなる。弛緩
量は２〜１０％が適当である。Furthermore, the effect of the present invention is enhanced by performing a treatment accompanied by relaxation (hereinafter also referred to as "relaxation heat treatment") in a part of the steps of the heat fixing section or the cooling section. The heat treatment with relaxation means the opposing clip interval (horizontal direction, T
In this method, the clip pitch in D) or the flow direction (vertical direction, MD) is slightly returned from the maximum draw ratio, and the film is heat-treated while being loosened from the tensioned state. The relaxation heat treatment operation can reduce the hot water shrinkage rate of the stretched film without raising the heat treatment temperature so much, so that it is possible to prevent the film from being whitened or the strength being reduced during the heat treatment. Although only the relaxation treatment in the horizontal direction which is simple in terms of equipment is effective, the present invention becomes more useful when it is accompanied by the relaxation treatment in both the vertical and horizontal axes. A relaxation amount of 2 to 10% is suitable.

【００１３】本発明においては、熱処理後のフィルムは
クリップから離される前に、加湿空気の露点以下、すな
わち少なくとも１００℃以下に冷却する必要がある。そ
のため、延伸機には熱処理ゾーンの後に冷却ゾーンが設
けられ、熱処理後、通常連続的に、後記する方法により
フィルムを冷却し、その後フィルムを調湿するものであ
る。In the present invention, the heat treated film must be cooled to below the dew point of the humidified air, ie at least 100 ° C. or less, before being released from the clip. Therefore, the stretching machine is provided with a cooling zone after the heat treatment zone, and after the heat treatment, the film is usually continuously cooled by the method described below, and then the humidity of the film is adjusted.

【００１４】調湿段階で短時間にフィルムを吸湿させる
ためには、フィルムの温度とフィルムに接する空気の湿
度についての条件を最適にする工夫が必要である。フィ
ルムの吸水速度は、フィルム表面における空気の相対湿
度によってほとんど決定されるフィルム表面の吸着水分
濃度と、フィルムの厚さ方向に水分子が移動する速度を
決定する拡散係数の積に比例する。但しポリアミドのよ
うな親水性ポリマーでは、拡散係数は表面水分濃度に大
きく左右される。親水性ポリマーは多くの極性基を有
し、水分濃度の低いところではこれらの極性基間の相互
作用（水素結合）のため水分子の拡散は著しく阻害さ
れ、加えて低濃度では収着された水は極在化しているの
で、拡散係数は低い値を示す。そして、水分濃度の増加
とともにこれらの水素結合は漸次破壊されて、拡散係数
が増大してゆくことが知られている。このような原理か
ら、ポリアミドのような親水性ポリマーの吸水速度はフ
ィルム表面の水分濃度に著しく依存し、水分濃度の増大
に伴って指数関数的に増大する。In order to allow the film to absorb moisture in a short time in the humidity control stage, it is necessary to devise a condition for optimizing the conditions of the temperature of the film and the humidity of the air in contact with the film. The water absorption rate of a film is proportional to the product of the adsorbed moisture concentration on the film surface, which is mostly determined by the relative humidity of the air on the film surface, and the diffusion coefficient, which determines the speed at which water molecules move in the thickness direction of the film. However, for hydrophilic polymers such as polyamides, the diffusion coefficient is highly dependent on the surface water concentration. Hydrophilic polymer has many polar groups, and the diffusion of water molecules was significantly hindered by the interaction (hydrogen bond) between these polar groups at low water concentration, and it was sorbed at low concentration. Since water is localized, the diffusion coefficient shows a low value. It is known that these hydrogen bonds are gradually broken and the diffusion coefficient increases as the water concentration increases. From such a principle, the water absorption rate of a hydrophilic polymer such as polyamide remarkably depends on the water concentration on the film surface, and increases exponentially as the water concentration increases.

【００１５】このような理由から、フィルムへの吸水速
度を上げるためには、フィルム表面の相対湿度を飽和に
近い状態まで上げることが重要であり、また効果的であ
る。フィルム表面の相対湿度を上げるためには、吹き付
ける加湿空気の相対湿度を高くすれば良いが、あまり高
くし過ぎると、オーブン内で局部的に加湿空気が冷却さ
れることにより露結した水がフィルム表面に落下し、フ
ィルム表面を汚すことになり好ましくない。そこで本発
明においては、加湿空気の相対湿度を高くすることなく
フィルムを効果的に調湿するため、加湿空気を吹き付け
る前にフィルムを該加湿空気の露点以下の温度まで冷却
することにより、加湿ゾーンでのフィルム表面の相対湿
度を飽和に近い状態にして、吸水速度を増大させるので
ある。For these reasons, it is important and effective to raise the relative humidity of the film surface to a state close to saturation in order to increase the water absorption rate of the film. In order to raise the relative humidity of the film surface, the relative humidity of the humidified air to be sprayed may be raised, but if it is set too high, the water that has condensed due to the localized cooling of the humidified air in the oven will form a film. It is not preferable because it falls on the surface and stains the film surface. Therefore, in the present invention, in order to effectively regulate the humidity of the film without increasing the relative humidity of the humidified air, by cooling the film to a temperature below the dew point of the humidified air before blowing the humidified air, the humidification zone The relative humidity of the film surface is brought to a state close to saturation and the water absorption rate is increased.

【００１６】フィルムを冷却する方法としては種々考え
られる。例えば冷風をフィルムに吹き付ける方法でも構
わないが、特にフィルムに水滴を噴霧する方法が最も効
果的である。前者のフィルムに冷風を吹き付ける方法で
は、前後のゾーンの熱風の影響もありフィルムの冷却効
果があまり高くなく、十分な冷却効果を発現させるため
には大がかりな設備を必要とする。これに対し後者の水
滴を噴霧する方法は、フィルムに添着した水が蒸発する
際にフィルムより奪う気化熱により冷却する方法である
ため、冷却効果が非常に高い。また既存のオーブン内に
水スプレーガンを設置するだけでよいので、非常に簡単
な設備で実現できることも大きな利点である。There are various possible methods for cooling the film. For example, a method of blowing cold air on the film may be used, but a method of spraying water droplets on the film is most effective. In the former method, in which cold air is blown to the film, the effect of the hot air in the front and back zones is not high, and the film cooling effect is not so high. Therefore, a large-scale facility is required in order to exert a sufficient cooling effect. On the other hand, the latter method of spraying water droplets is a method of cooling by the heat of vaporization taken from the film when water attached to the film is evaporated, and therefore has a very high cooling effect. Moreover, since it is only necessary to install a water spray gun in the existing oven, it is also a great advantage that it can be realized with a very simple facility.

【００１７】水滴の噴霧方法は、市販のスプレーガンを
オーブンの幅方向に数個〜数十個並べて設置し噴霧すれ
ば良い。噴霧水量は延伸フィルムの水分率及びフラット
性を評価して適当な量に設定する。噴霧する水滴の粒径
は特に限定しないが、小さすぎるとフィルム表面に到達
する水滴量が少なくなり冷却効果が著しく悪化し、大き
すぎるとフィルム表面に添着する水滴の斑が生じて良く
ない。As a method of spraying water droplets, several to several tens of commercially available spray guns may be arranged side by side in the width direction of the oven and sprayed. The amount of water sprayed is set to an appropriate amount by evaluating the water content and flatness of the stretched film. The particle size of the water droplets to be sprayed is not particularly limited, but if it is too small, the amount of water droplets that reach the film surface will be small, and the cooling effect will be markedly deteriorated, and if it is too large, water droplets attached to the film surface will be uneven.

【００１８】熱固定後のフィルムを急冷すると、ボーイ
ング現象に起因する幅方向の物性差が潜在していて、特
に収縮応力の緩和が不十分なままクリップから離れるた
め、幅方向に収縮量の差異が現れ、たるみや片伸びを生
じ最終的にフィルムのフラット性が悪くなる。このた
め、熱固定後に急冷せず、徐冷するこにより潜在収縮能
の大きな部分方向の収縮応力が優先的に緩和することに
よってフィルムのフラット性を改良する方法がポリエチ
エンテレフタレートを中心として行われている。本発明
では熱固定後に急冷操作を行っているが、その後フィル
ムを加湿した熱風を吹き付ける工程に通過させているた
め、上述の緩和効果はそれほど低下しない。When the film after heat setting is rapidly cooled, there is a potential difference in the physical properties in the width direction due to the bowing phenomenon, and since the film is separated from the clip with insufficient relaxation of the shrinkage stress, the difference in the shrinkage amount in the width direction is large. Appears, and sagging or unilateral stretching occurs, and finally the flatness of the film deteriorates. For this reason, a method of improving the flatness of the film by preferentially relaxing the shrinkage stress in the direction of the part having a large latent shrinkage by gradually cooling without heat-fixing after heat setting is mainly performed with polyethylene terephthalate. ing. In the present invention, the quenching operation is performed after heat fixing, but since the film is then passed through the step of blowing humidified hot air, the above-mentioned relaxation effect does not decrease so much.

【００１９】調湿によるフィルムの水分率は０．５〜
２．０％が最も適している。該水分率が０．５％以下で
は、吸湿によって緩和を促進させる効果やその後の吸湿
による寸法変化を鈍化させる効果がなく、２．０％以上
では吸湿によりスリップ性が低下したり、吸湿ムラが生
じてフィルムの均一性を悪化させるからである。The moisture content of the film due to humidity control is 0.5 to
2.0% is the most suitable. When the moisture content is 0.5% or less, there is no effect of promoting relaxation by moisture absorption or an effect of blunting a dimensional change due to moisture absorption after that, and when it is 2.0% or more, slip property is deteriorated by moisture absorption and uneven moisture absorption occurs. This is because it occurs and deteriorates the uniformity of the film.

【００２０】本発明方法の適用を受けるポリアミドとは
通常のフィルム形成性ポリアミド樹脂であるが、特にポ
リε−カプロアミドに対しては本発明の効果が大きいの
で、該ポリアミドに適用することが好ましい。The polyamide to which the method of the present invention is applied is a usual film-forming polyamide resin, but since the effect of the present invention is particularly large for poly ε-caproamide, it is preferable to apply it to the polyamide.

【００２１】本発明方法においては、ポリアミドの二軸
延伸フィルムを１００℃の熱水中に１５分間浸漬し、浸
漬前後のタテ方向、ヨコ方向の標線間寸法を２０℃、６
５％ＲＨの雰囲気下で測定したときの浸漬による収縮率
がタテ方向、ヨコ方向とも３％以下となるように高度の
熱固定（熱処理）を行ったフィルムに対して適用され
る。熱処理方法としては、前記のようにタテ方向および
ヨコ方向の両軸方向の弛緩処理を伴う熱処理を行うこと
により熱水中の収縮率が特に小さくなるが、この場合に
おいて、本発明の効果は特に顕著である。In the method of the present invention, the biaxially stretched polyamide film is immersed in hot water at 100 ° C. for 15 minutes, and the dimension between the marked lines in the vertical direction and the horizontal direction before and after the immersion is 20 ° C., 6
It is applied to a film that has been subjected to a high degree of heat fixation (heat treatment) so that the shrinkage rate due to immersion when measured in an atmosphere of 5% RH is 3% or less in both the vertical and horizontal directions. As the heat treatment method, the shrinkage rate in hot water is particularly reduced by performing the heat treatment involving the relaxation treatment in both the vertical direction and the horizontal direction as described above, but in this case, the effect of the present invention is particularly It is remarkable.

【００２２】[0022]

【作用】本発明の方法により製造されたポリアミド二軸
延伸フィルムは、巻き取り直後のフィルムのフラット性
が改良され、しかもその効果が従来品にくらべて安定し
ており、例えば、気候、季節の影響を受けない。これは
熱固定後の急冷操作、その後の加湿冷却過程でフィルム
の水分率を積極的にコントロールするためと、加湿冷却
工程におけるいわゆる湿熱セット効果の相乗効果で雰囲
気湿度の影響を緩和するためであると考えられる。The polyamide biaxially stretched film produced by the method of the present invention has improved flatness of the film immediately after winding, and its effect is more stable than the conventional product. Not affected. This is for the purpose of positively controlling the water content of the film in the rapid cooling operation after heat setting and the subsequent humidification cooling process, and for mitigating the influence of atmospheric humidity by the synergistic effect of the so-called wet heat setting effect in the humidification cooling process. it is conceivable that.

【００２３】次に本発明方法により製造されたフィル
ム、すなわち０．５〜２．０％に調湿され、湿熱セット
効果を受けたフィルムは、その後の使用条件における雰
囲気湿度の変化に対する寸法変化が緩和される。絶乾状
態のポリアミド二軸延伸フィルムに徐々に水分を与えて
いくとき、吸湿の初期（０．５〜２．０％）において大
きな寸法変化の生じることが多い。したがって、あらか
じめこの範囲の水分を与えておけばその後の寸法変化は
緩和される。たとえば、絶乾状態で巻き取ったフィルム
巻物を通常の雰囲気に放置しておくと吸湿膨潤によりフ
ィルム巻物にはしわが発生するが、本発明により巻取ら
れたフィルム巻物ではその程度が小さくなる。また、ポ
リアミド二軸延伸フィルムは印刷、ラミネート、製袋な
どの後加工を得てから包装材料として使われるのが一般
的であるが、この工程においても吸湿による寸法変化は
数々のトラブルを引き起こしやすい。たとえば、印刷、
ラミネート工程でのフィルムのカール、製袋品のカール
現象、内容物充填時のトラブルなどである。本発明の方
法により製造されたフィルムはすでに調湿されていて、
雰囲気湿度とフィルム水分率の変化に対して反応しにく
いものとなっているため、後加工工程および最終使用時
の吸湿寸法変化によるトラブルは大幅に削減される。Next, the film produced by the method of the present invention, that is, the film whose humidity has been adjusted to 0.5 to 2.0% and which has been subjected to the wet heat setting effect, has a dimensional change with respect to a change in atmospheric humidity under the subsequent use conditions. Will be alleviated. When water is gradually added to the absolutely dry polyamide biaxially stretched film, a large dimensional change often occurs in the initial stage of moisture absorption (0.5 to 2.0%). Therefore, if moisture in this range is given in advance, the subsequent dimensional change is alleviated. For example, when the film roll wound in an absolutely dry state is left to stand in a normal atmosphere, wrinkles are generated in the film roll due to swelling due to moisture absorption, but to a lesser extent in the film roll wound according to the present invention. In addition, polyamide biaxially stretched film is generally used as a packaging material after obtaining post-processing such as printing, laminating, and bag making, but even in this process, dimensional changes due to moisture absorption easily cause various troubles. .. For example, print,
This includes curling of the film during the laminating process, curling of bag-making products, and troubles when filling the contents. The film produced by the method of the present invention has already been conditioned,
Since it is difficult to react to changes in atmospheric humidity and film moisture content, troubles due to changes in moisture absorption dimensions during post-processing and final use are greatly reduced.

【００２４】[0024]

【実施例】次に比較例および実施例で本発明を具体的に
説明する。なお、測定は以下の方法で行った。EXAMPLES The present invention will be specifically described with reference to Comparative Examples and Examples. The measurement was carried out by the following method.

【００２５】（水分率）巻き取り直後の巻物からフィル
ムをサンプリングし、ひょう量瓶に入れた後、乾燥し、
乾燥前後の重量変化より水分率を算出した。(Moisture Content) A film was sampled from a roll immediately after winding, put in a weighing bottle, and then dried.
The water content was calculated from the change in weight before and after drying.

【００２６】（熱水収縮率）タテ方向（ＭＤ）、ヨコ方
向（ＴＤ）それぞれ標線を記入した短冊試料を切り出
し、１００℃の沸騰水中で１０分間処理し、処理後の標
線間寸法を２０℃、６５％ＲＨ平行状態で測定し、処理
による縮み量の処理前寸法に対する百分率で表した。(Hot water shrinkage rate) A strip sample having marked lines in the vertical direction (MD) and the horizontal direction (TD) was cut out and treated in boiling water at 100 ° C for 10 minutes, and the dimension between the marked lines after treatment was measured. It was measured at 20 ° C. and 65% RH in parallel, and expressed as a percentage of the amount of shrinkage due to treatment with respect to the dimension before treatment.

【００２７】（タルミ）フィルム幅の２倍の距離をおい
て平行に並べられたロール間にフィルムを乗せ、全幅均
一に０．５ｋｇ／ｍのテンションをかけてフィルムを張
る。２本のロール間の中央部にロールに平行でフィルム
面より少し高い位置にスケールをセットし、そのスケー
ルからフィルム面までの距離を幅方向１０点程測定し、
その距離の最大値と最小値の差をタルミ量とした。(Talumi) The film is placed between rolls arranged in parallel at a distance twice the width of the film, and a tension of 0.5 kg / m is applied uniformly over the entire width to stretch the film. Set the scale in the center between the two rolls in a position parallel to the rolls and slightly higher than the film surface, measure the distance from the scale to the film surface about 10 points in the width direction,
The difference between the maximum value and the minimum value of the distance was taken as the amount of Talmi.

【００２８】（フィルム外観）延伸フィルム巻物を２０
℃、６５％ＲＨの雰囲気に１時間放置した後、巻物表面
のシワの発生程度を○、△、×の３段階評価を行った。
（○はシワの発生なし、△は部分的にシワ発生、×は全
面的に強いシワ発生）(Film appearance) 20 stretched film rolls
After left in an atmosphere of 65 ° C. and 65% RH for 1 hour, the degree of occurrence of wrinkles on the surface of the roll was evaluated by three grades of ◯, Δ, and ×.
(○ indicates no wrinkles, Δ indicates partial wrinkles, and × indicates strong wrinkles on the whole surface)

【００２９】（比較例１）熱処理部の後半にＭＤ、ＴＤ
それぞれに５％の同時弛緩処理部を持ち、熱処理部に続
いてそれぞれの長さが、２．５ｍと１．５ｍの第一冷却
部および第２冷却部を備えた同時二軸延伸機で、厚さ１
５μｍのポリε−カプロアミドフィルムを、第１冷却部
および第２冷却部の冷却空気温度がともに８０℃、速度
１２０ｍ／分で５０００ｍ製造した。(Comparative Example 1) MD, TD are provided in the latter half of the heat treatment section.
A simultaneous biaxial stretching machine having a 5% simultaneous relaxation treatment section for each, and a heat treatment section followed by a first cooling section and a second cooling section each having a length of 2.5 m and 1.5 m, Thickness 1
A 5 μm poly ε-caproamide film was produced at a cooling air temperature of 80 ° C. in both the first cooling section and the second cooling section at a speed of 120 m / min for 5000 m.

【００３０】（比較例２）第１冷却部および第２冷却部
のファン吹込み部に蒸気を吹き込んで冷却空気を温度８
０℃、絶対湿度０．１４（ｋｇ水蒸気／ｋｇ乾燥空気）
にコントロールした以外は比較例１と同じ条件でフィル
ムを５０００ｍ製造した。なお、この冷却空気の露点は
５８℃で第１冷却部直前のフィルム温度は１６０℃であ
った。(Comparative Example 2) Steam was blown into the fan blowing portions of the first cooling portion and the second cooling portion to cool the cooling air at a temperature of 8 ° C.
0 ° C, absolute humidity 0.14 (kg steam / kg dry air)
A film was produced for 5,000 m under the same conditions as in Comparative Example 1 except that the film thickness was controlled to 1. The dew point of this cooling air was 58 ° C, and the film temperature immediately before the first cooling part was 160 ° C.

【００３１】（比較例３）速度を１６０ｍ／分にした以
外は比較例２と同じ条件でフィルムを５０００ｍ製造し
た。Comparative Example 3 A film was produced for 5000 m under the same conditions as in Comparative Example 2 except that the speed was set to 160 m / min.

【００３２】（実施例１）延伸機熱処理部の最後尾、第
１冷却部直前のフィルム下面４０ｃｍの位置に幅方向に
２０ｃｍ間隔でスプレーガン（扶桑精機製「ＨＭ−１
型」）を設置した。また、個々のスプレーガンの噴霧水
量は流量計および流量調節弁により調節可能な設備とし
た。 全てのスプレーガンの噴霧水量を８０ｇ／分に調
節してフィルムに水を噴霧し、第１冷却部直前のフィル
ム温度を５５℃に冷却した以外は比較例２と同じ条件で
フィルムを５０００ｍ製造した。(Example 1) A spray gun ("HM-1" manufactured by Fuso Seiki Co., Ltd.) was placed at a position of 40 cm on the lower surface of the film immediately before the first cooling section at the end of the heat treatment section of the stretching machine at intervals of 20 cm in the width direction.
Type ”) was installed. The amount of water sprayed from each spray gun was controlled by a flow meter and flow control valve. A film of 5000 m was produced under the same conditions as in Comparative Example 2 except that the amount of water sprayed from all spray guns was adjusted to 80 g / min and water was sprayed onto the film, and the film temperature immediately before the first cooling part was cooled to 55 ° C. ..

【００３３】（実施例２）フィルムの生産速度を１６０
ｍ／分とし、全てのスプレーガンの噴霧水量を１０５ｇ
／分に調節し、第１冷却部直前のフィルム温度を５６℃
に冷却した以外は実施例１と同じ条件でフィルムを５０
００ｍ製造した。フィルムの生産速度および得られたフ
ィルムの水分率、熱水収縮率、タルミ量、およびフィル
ム外観を表１に示す。(Example 2) A film production rate of 160
m / min, spray water amount of all spray guns is 105g
/ Min, and the film temperature just before the 1st cooling part is 56 ℃
The film was prepared under the same conditions as in Example 1 except that the film was cooled to 50.
It was manufactured to 00 m. Table 1 shows the production rate of the film, the water content of the obtained film, the hot water shrinkage ratio, the amount of tarmi, and the film appearance.

【００３４】[0034]

【表１】 [Table 1]

【００３５】[0035]

【発明の効果】比較例１〜３の結果からわかるように、
比較例２で延伸機冷却部を加湿することによりフィルム
の水分率が高くなり、タルミが改良されているが、比較
例３のように製造速度が高速になると、この効果が半減
している。これに対して、実施例に示されるように本発
明の方法を用いると、高速度生産でもフラット性のきわ
めて良好なフィルムが製造可能となった。As can be seen from the results of Comparative Examples 1 to 3,
By humidifying the cooling part of the stretching machine in Comparative Example 2, the moisture content of the film is increased and the tarmi is improved, but when the production speed is high as in Comparative Example 3, this effect is halved. On the other hand, as shown in the examples, by using the method of the present invention, it was possible to produce a film having extremely good flatness even in high-speed production.

【００３６】また、本発明方法により調湿されたフィル
ムは巻物表面に小ジワが発生しにくく、外観が非常に良
くなった。そして、印刷、ラミネート、製袋、充填など
の後加工工程において従来しばしば問題になっていた吸
湿によるカール、タルミ、しわなどの発生を低減するこ
とが可能となった。Further, the film of which the humidity was adjusted by the method of the present invention was less likely to have small wrinkles on the surface of the scroll, and the appearance was very good. Further, it has become possible to reduce the occurrence of curls, tarmi, wrinkles, etc. due to moisture absorption, which have often been a problem in post-processing steps such as printing, laminating, bag making and filling.

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 ポリアミドフィルムを二軸延伸した後、
１００℃の熱水中の収縮率がタテ方向、ヨコ方向とも３
％以下になるように熱固定し、その後連続的に温度１５
０℃以下の加湿空気を吹きつけながらフィルムの水分率
を０．５〜２．０％の範囲に調湿してフィルムを巻き取
るポリアミド二軸延伸フィルムの製造方法において、加
湿空気を吹き付ける前にフィルムを該加湿空気の露点以
下に冷却することを特徴とするポリアミド二軸延伸フィ
ルムの製造方法。1. After biaxially stretching a polyamide film,
Shrinkage in hot water at 100 ° C is 3 in both vertical and horizontal directions
% So that it does not exceed 15%
In a method for producing a polyamide biaxially stretched film in which the moisture content of a film is adjusted to a range of 0.5 to 2.0% while blowing humidified air at 0 ° C. or less, and the film is wound, before blowing humidified air A method for producing a polyamide biaxially stretched film, which comprises cooling the film below the dew point of the humidified air. 【請求項２】 二軸延伸後の熱固定が、ヨコ方向または
ヨコ方向およびタテ方向両軸の弛緩を伴う熱処理である
ことを特徴とする請求項１記載のポリアミド二軸延伸フ
ィルムの製造方法。2. The method for producing a polyamide biaxially stretched film according to claim 1, wherein the heat setting after the biaxial stretching is a heat treatment accompanied by relaxation of the horizontal direction or both the horizontal direction and the vertical direction. 【請求項３】 加湿空気を吹き付ける前のフィルムの冷
却方法が、水滴をフィルムに噴霧する方法であることを
特徴とする請求項１または２記載のポリアミド二軸延伸
フィルムの製造方法。3. The method for producing a polyamide biaxially stretched film according to claim 1, wherein the method of cooling the film before blowing the humidified air is a method of spraying water drops on the film.