JP3766122B2 - Catheter balloon and manufacturing method thereof - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、拡張操作を目的とする手術に使用されるカテーテルとその製造方法に関するもので、特に血管拡張用カテーテルに関するものである。
【０００２】
【従来の技術】
拡張カテーテルは狭窄、または閉塞した血管に対しての血管形成治療に用いられている。この治療においては、カテーテルのバルーン部は患者の動脈を経て狭窄部位中に挿入されねばならず、そのためバルーン部が小断面であること（ロー・プロファイル）、バルーン部を含めたカテーテル先端部が血管追随性に優れていること、すなわち柔軟性に富んでおり、かつ、ガイドワイヤとの摩擦が少ないことが要求されている。この両者の要求を満たすためバルーン部分の薄膜化が研究されてきている。この薄膜化を目的とした従来の血管拡張用カテーテルに使用されるバルーンの成型方法は、特公昭６３−２６６５５や特公平３−６３９０８に示される様に、バルーンの原料パリソンを二次転移温度以上において軸方向に延伸を加え、その後、型内で吹き込み成形を行い円周方向に延伸、二次延伸された高強度バルーンを得るというものであった。
【０００３】
一般に、バルーンを成形する際には、上記の方法によって得られるバルーンの円錐部の肉厚は円筒部より離れるに従って円筒部の肉厚より厚くなる事は避けられない。このためバルーンを血管に挿入するために収縮させシャフト部周囲に折りたたんだ場合に、円錐部の肉厚が厚い故に折りたたみが困難であったり、折りたたんだ円錐部の断面がその近傍のカテーテルの断面より大きくなり、バルーン部端に突起が生じる場合があった。したがって、カテーテルの血管中を通過させる性能、狭窄部を突破させる性能が低下し、さらに挿入された血管部、他組織を損傷するという危険もあった。
【０００４】
これらの問題を解決するために、予めパリソンの円錐部を形成すると考えられる部分を選択的に薄膜化しておき、円錐部の肉厚を薄くコントロールするバルーンの製法（特開平２−４３８７、特開平４−１７６４７３）や、バルーン円筒部を複層化し円錐部を薄くしたバルーン（特開平４−２３１０７０）が提案されている。
【０００５】
【発明が解決しようとする課題】
上記のように医療用カテーテルのバルーン部分を作製するために高強度化、薄肉化、円筒部と円錐部の肉厚比の低下と数々の努力が試されてきた。しかし、我々はバルーン作製を研究する過程、特にバルーンの破壊特性を詳細に検討した際において、従来の技術で作製されたバルーンは円筒部から円錐部への遷移部近傍から破壊をきたす場合が多いということに気づいた。その原因を更に調査した結果、従来の技術によって作製されたバルーンは円筒部から円錐部への遷移部近傍及び円錐部に分子配向ムラが存在することが判った。
【０００６】
上述したように、拡張用カテーテルバルーンは二軸延伸によって加工作製される。延伸は高分子材料を軟化点以上の温度で引っ張り、分子を配向させ、強度を増すプロセスである。延伸においては、材料のどの部分にも均一な温度と応力及び延伸量が維持されることが不可欠である。温度に関しては材料が十分に軟化されていない状態で延伸すると応力が不均一となり延伸ムラが生じ、温度が高すぎると延伸時の配向緩和の温度依存性が大きくなり、わずかな温度ムラが配向ムラとなる。応力、延伸量に関してはテンターなどを用いるフィルム延伸ではフィルム材料内で一様な応力、延伸量が加えられるが、型内で延伸をおこなう際には型内の形状により材料に加えられる応力、延伸量が一定ではないため材料全体が一様な延伸状態になることは難しい。バルーンの場合は円筒部と円錐部からなる型内で延伸ブローするので、円筒部と円錐部では延伸の程度が異なり延伸ムラが生じやすいことは明白である。バルーン部分は高分子材料を高度に延伸することによって高強度に作製されるが、延伸による配向がそろっていないと当然その部分の強度は低下するのでバルーンとして耐圧性を上げるために厚肉となっていた。従って、均一な延伸を行いバルーンの部位による配向ムラを無くしてやることにより成型品としての強度を上げ、また強度が上昇した分だけ薄肉化することが可能である。
【０００７】
また上述したように、バルーン円錐部の肉厚を薄くすることは重要であると考えられているが、そのためには特開平２−４３８７の如く予めチューブを予備的に加工しておくような操作が必要であったり、また特開平４−２３１０３０の如くバルーン円筒部を積層化するような煩雑な操作が必要であった。。
【０００８】
本発明はバルーン円筒部、円錐部の配向ムラを無くした、より一層耐圧性が向上した、バルーン部が薄肉化されたカテーテルバルーン及びその製造方法を提供するものである。さらに本発明は、バルーン円筒部と円錐部の肉厚の差を小さくしたカテーテルバルーン及びカテーテルバルーンの容易な製造方法を提供するものである。
【０００９】
【課題を解決するための手段】
本発明は、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の円筒部と円錐部の肉厚の比が円筒部を形成される前のチューブとの比より比較的小で、両方又は一方の、円筒部から円錐部にかけて延伸ムラ、配向ムラの少ない事を特徴とするカテーテルバルーン、特に主延伸方向（円周方向）への分子配向のムラが円筒部、円筒部と円錐部の境界近傍部、円錐部で比較的小である事を特徴とする拡張用カテーテルバルーンを提供することにより上記目的を達成するものである。
【００１０】
即ち、本発明の第１は、延伸加工が可能な高分子材料から形成され、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての円周方向の主屈折率がそのバルーンを形成する材料の固有屈折率より常に大きく、且つ円周方向の複屈折率が常に０より大きいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１１】
本発明の第２は、延伸加工が可能な高分子材料から形成され、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての円周方向の配向係数が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に１／３より大きいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１２】
本発明の第３は、延伸加工が可能な高分子材料から形成され、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての円周方向の配向度が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に０より大きいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１３】
本発明の第４は、延伸加工が可能な高分子材料から形成され、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての膜厚方向の配向係数が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に１／３より小さいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１４】
本発明の第５は、延伸加工が可能な高分子材料から形成され、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての膜厚方向への配向度が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に０より小さいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１５】
本発明の第６は、延伸加工が可能な負の屈折率を持つ高分子材料から形成され、円筒部との両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけて円周方向の主屈折率がそのバルーンを形成する材料の固有屈折率より常に小さく、且つ円周方向の複屈折率が常に０より小さいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１６】
本発明の第７は、延伸加工が可能な高分子材料からなるチューブ状パリソンを二次転移温度以上で型内で円周方向に延伸しバルーンの形成を開始すると同時に、チューブ状パリソンに軸方向にかかっている応力の変化に応じて型の外部分のチューブの両側または外側を軸方向にバルーンと反対側へ移動させて得られる、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての円周方向の主屈折率がそのバルーンを形成する材料の固有屈折率より常に大きく、且つ円周方向の複屈折率が常に０より大きいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１７】
本発明の第８は、延伸加工が可能な高分子材料からなるチューブ状パリソンを二次転移温度以上で型内で円周方向に延伸しバルーンの形成を開始すると同時に、チューブ状パリソンに軸方向にかかっている応力の変化に応じて型の外部分のチューブの両側または外側を軸方向にバルーンと反対側へ移動させて得られる、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての円周方向の配向係数が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に１／３より大きいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１８】
本発明の第９は、延伸加工が可能な高分子材料からなるチューブ状パリソンを二次転移温度以上で型内で円周方向に延伸しバルーンの形成を開始すると同時に、チューブ状パリソンに軸方向にかかっている応力の変化に応じて型の外部分のチューブの両側または外側を軸方向にバルーンと反対側へ移動させて得られる、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての円周方向の配向度が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に０より大きいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００１９】
本発明の第１０は、延伸加工が可能な高分子材料からなるチューブ状パリソンを二次転移温度以上で型内で円周方向に延伸しバルーンの形成を開始すると同時に、チューブ状パリソンに軸方向にかかっている応力の変化に応じて型の外部分のチューブの両側または外側を軸方向にバルーンと反対側へ移動させて得られる、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての膜厚方向の配向係数が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に１／３より小さいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００２０】
本発明の第１１は、延伸加工が可能な高分子材料からなるチューブ状パリソンを二次転移温度以上で型内で円周方向に延伸しバルーンの形成を開始すると同時に、チューブ状パリソンに軸方向にかかっている応力の変化に応じて型の外部分のチューブの両側または外側を軸方向にバルーンと反対側へ移動させて得られる、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけての膜厚方向への配向度が円筒部、円筒部と円錐部の境界近傍部、円錐部で常に０より小さいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００２１】
本発明の第１２は、延伸加工が可能な負の屈折率を持つ高分子材料からなるチューブ状パリソンを二次転移温度以上で型内で円周方向に延伸しバルーンの形成を開始すると同時に、チューブ状パリソンに軸方向にかかっている応力の変化に応じて型の外部分のチューブの両側または外側を軸方向にバルーンと反対側へ移動させて得られる、円筒部との両端に外側に向かい径小に傾斜する円錐部分を有するカテーテルバルーンであって、両方又は一方の、円筒部から円錐部にかけて円周方向の主屈折率がそのバルーンを形成する材料の固有屈折率より常に小さく、且つ円周方向の複屈折率が常に０より小さいことを特徴とする拡張用カテーテルバルーンを内容とする。
【００２２】
本発明の第１３は、延伸加工が可能な高分子材料からなるチューブ状パリソンを型内に配置し二次転移温度以上で圧力気体を吹き込みカテーテルバルーンを成形するに際し、チューブ状パリソンが円周方向へ延伸しバルーンの形成を開始すると同時にチューブ状パリソンの軸方向にかかっている応力の変化を検知し、該応力の変化に応じて型の外部分のチューブの両側または片側を軸方向にバルーンと反対側へ移動させる操作を行うことを特徴とする拡張用カテーテルバルーンの製造方法を内容とする。
【００２３】
本発明のカテーテルバルーンは、例えば図１に示す如き装置を用いて製造される。即ち、バルーンに成形されるのに適切な材質、直径、肉厚であるチューブ１を型２内に導入し、チューブ状パリソン３を型２内に配置し、空気、窒素等の圧力気体８をパリソン内に導入してブロー成形する際に、バルーンが型内で膨張を開始するのと同時にチューブ状パリソン３の軸方向の応力変化をフォースゲージの如き検知手段４で検知し、固定部５、６でチューブ１を保持したまま軸方向で且つバルーンと反対側へスライドテーブル７上を移動させることによりチューブ１を移動させて製造される。この場合、ブロー成形の前にチューブ１の軸方向へ延伸を加えておくと、より好ましい結果が得られる。
本発明の好ましい実施状態においては、バルーン円筒部から円錐部までほぼ一定の延伸状態であるバルーンが得られる。特に円筒部の円錐部近傍における十分に延伸されにくい部分の延伸が的確に行われて配向ムラが無くなる。また、本発明のバルーンの円錐部の肉厚は、ブロー成形の際にチューブを軸方向へ移動させる操作を加えない場合に比べて薄くなり、円筒部の肉厚との比も比較的小となる。
【００２４】
拡張用カテーテルに用いるバルーン部分は、拡張時にかけられる内圧に対して十分な強度を与えるため延伸加工によって作られる。高分子材料は延伸により力学的性質、光学的性質、熱的、電気的性質の異方性が出現する。このような物理的性質の異方性は、延伸による結晶、非結晶相内に介在する高分子鎖の配向によって支配される。したがって、分子配向の評価は異方性の評価によって行うことが可能である。
【００２５】
バルーン部の素材としては延伸加工が可能な高分子材料なら制限されず選択でき、例えばポリエチレン、ポリプロピレン、ポリエステル、ポリウレタン、ポリアミド、ポリエチレンテレフタレート、ポリスチレン、ポリビニルアルコール、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリイミド、ポリアセチレン、ポリサルフォン等の高分子材料とその共重合体、混合体が適用可能である。それらは下記のような種々の評価法をその材料の特徴に則して用いることにより、材料中の分子配向として延伸の状態が評価可能である。
【００２６】
一般に延伸した高分子は各種分光学的手法によって配向状態を評価される。具体的には顕微偏光分光光度計や屈折計を用いる複屈折の測定法、広角Ｘ線回折、小角Ｘ線散乱、変更蛍光法、レーザーラマン散乱法による配向評価があるが、これらの配向の特徴は配向係数、配向度によって表現される。配向係数は下記（ａ）の如く、延伸方向に対する分子鎖、結晶主軸の配向（全分子配向）の方向余弦の２乗平均値であり、これより下記（ｂ）の如く、配向度が求められる。分子鎖および結晶が延伸方向に完全に配向した場合は、下記（ｃ）の如くとなる。配向に方向性が無い場合は下記（ｄ）の如くである。延伸方向に完全に垂直に配向した場合は、下記（ｅ）の如くである。すなわち配向係数が１／３より大きく、配向度が０より大きい場合は延伸方向に配向が存在し、配向係数が１／３より小さく、配向度が０より小さい場合は延伸方向と垂直な配向が存在することを示している。
【００２７】
【数１】
高分子膜の理想的な延伸においては、延伸方向と平行に分子鎖、結晶主軸が配向するため常に延伸方向の配向係数は１／３より大きく、配向度が０より大きくなり、且つ、膜厚方向は延伸方向とそれに平行な分子配向と垂直になるために常に配向係数が１／３より小さく、配向度が０より小さくなる。
【００２９】
また、本明細書中では屈折率の測定より分子配向を評価しているので、延伸と屈折率の関係をもう少し詳しく述べると、物質の屈折率は分子の分極に起源し、たいていの分子は分極していることから光学的に異方性である。物質中に分子が方向性を示さずにランダムに分布している場合は、どの方向の分極率も等しくなり単一の屈折率が示されるが、延伸などの操作により分子および分子鎖、結晶主軸が配向すると光学的異方性が出現する。高分子膜の延伸、特に２軸延伸においては長さ、幅、厚さ方向に振動する光の屈折率が異なりそれぞれ３方向の主屈折率とされる。その場合、延伸方向と平行に分子鎖、結晶主軸が配向するため常に延伸方向の主屈折率がその材料の固有屈折率よりも大きくなり、複屈折率が０より大きくなる。
【００３０】
バルーン用素材としては、先述したように延伸可能な高分子材料とその共重合体、混合体が適用可能であるが、例えばポリスチレンやポリメチルメタクリレート及びその共重合体、混合体のように分子の配向方向と光軸が垂直になる場合、即ち負の屈折率を持つ素材は屈折率の評価は正の屈折率を持つ素材と反対となることに注意しなければならない。
【００３１】
本明細書中では顕微偏光分光光度計を用い、バルーンの円周方向、軸方向、膜厚方向のそれぞれの主屈折率、複屈折率を測定し、コンバーテック１９９４年９月、ｐ．７８〜８１、コンバーテック１９９４年１０月、ｐ．６３〜６７、コンバーテック１９９４年１２月、ｐ．４４〜４７、コンバーテック１９９５年１月、ｐ．４〜８、コンバーテック１９９５年２月、ｐ．３３〜３５に記載された方法によってバルーンの各方向の配向係数、配向度を求めて評価指標とした。
【００３２】
以下に本発明を実施例に基づいて更に詳細に説明するが、本発明はこれらのみに限定されるものではない。
【００３３】
【実施例】
実施例１
バルーンに成形されるのに適切な直径、肉厚である架橋したポリエチレン製チューブを内径２．５mmφの型内に配置し、１１５℃に加熱し、軸方向へ１．５倍延伸した後、チューブ内へ加圧窒素（６kg/cm2）を導入しチューブが円周方向へ延伸されるのをフォースゲージを用いて検知し、同時にチューブの両端をすばやく軸方向にバルーンの反対方向へ向けて４００mm/secの速度で移動させ、外径２．５mmのバルーンを成形した（バルーンＡ）。
【００３４】
比較例１
チューブの両端を軸方向にバルーンの反対方向にむけて移動させる操作を施さない以外は、実施例１と同様の方法で外径２．５mmのバルーン（バルーンＢ）を成形した。
【００３５】
比較例２、３
市販の公称外径２．５mmのポリエチレン製カテーテルバルーン（バルーンＣ）、市販のポリエチレンテレフタレート（ＰＥＴ）製のカテーテルバルーン（バルーンＤ）を比較対象とした。
【００３６】
上記バルーンＡ〜Ｄの肉厚、主屈折率、配向係数及び配向度を測定した。尚、図３に肉厚、主屈折率などを測定したバルーンの部所を示す。ａはバルーンの円筒部中央、ｂはバルーン円筒部と円錐部との境界から円筒部側へ０．５ｍｍの部位、ｃはバルーン円筒部と円錐部との境界から円錐部側へ０．５ｍｍの部位、ｄはバルーン円錐部中央である。
【００３７】
（１）バルーンの肉厚
本発明のバルーンＡ、比較例１のバルーンＢの、図３に示したａ〜ｄの各測定点での肉厚を測定した。結果は下記のとおりである。
【００３８】
【表１】
円錐部中央であるｄ点でのバルーンＡの肉厚はバルーンＢと比較して小さくなっており、シャフト部周囲に折りたたんだ場合はバルーンＡはバルーンＢより折りたたみ易く、折りたたんだ円錐部の断面もバルーンＡの方が小であった。
【００４０】
（２）主屈折率、配向係数、配向度
バルーンＡ〜Ｄについて、図２に示すように、円周方向（ｎｘ）、軸方向（ｎｙ）、厚さ方向（ｎｚ）の主屈折率、分子配向係数、分子配向度を図３に示す各測定部所での測定した。測定結果を計算結果として示す。
測定方法は顕微偏光分光光度計を用いてバルーン部分のレターデーションを測定、バルーン円周方向、軸方向、厚さ方向の主屈折率、分子配向係数、分子配向度を計算した。計算にはポリエチレンの固有屈折率として１．５１０、固有複屈折として０．０４９を、ＰＥＴの固有屈折率として１．６７４、固有複屈折として０．２１７を使用した。
【００４１】
【表２】
【表３】
【表４】
【表５】
これらの表から判るように、本発明のバルーンＡは比較バルーンＢ、Ｃ、Ｄと比べてバルーンの各部分で円周方向、軸方向、厚さ方向の主屈折率、配向係数、配向度の変動が少なく、延伸ムラが少ない。
特に、比較バルーンＢ、Ｃ、Ｄではバルーンの円筒部と円錐部の境界近傍で主屈折率、配向係数、配向度の値の変動が激しく、延伸にムラがあることがわかる。
【００４６】
また、比較バルーンＢ、Ｃ、Ｄでは円筒部と円錐部の境界付近で分子配向が見られない箇所がある他、円錐部中央ｄでは配向がほとんどみられない。屈折率については、本発明のバルーンＡはどの測定箇所においても常に円周方向の屈折率が固有屈折よりも大きく円周方向の配向が常に存在することがわかる。
更に、比較バルーンＢ、Ｃ、Ｄでは円周方向の屈折率が固有屈折率と同じ、つまり他方向と比べた円周方向の分子配向がみられないか、または円周方向の屈折率が固有屈折率より小さく、円周方向の分子配向より他方向の方が配向されている。
【００４７】
具体的に示すと、バルーンＡは各測定部所ａ、ｂ、ｃ、ｄのどの点においても円周方向の主屈折率が固有屈折率１．５１０より大きい値を示し且つ円周方向＞軸方向＞厚さ方向の関係を示しているが、比較バルーンＢ、Ｃ、Ｄにおいては上記関係を満たさず、また、測定部所ｄにおいて円周方向の主屈折率がバルーンＢ、Ｃは両方とも１．５１０と固有屈折率１．５１０よりも大きくない。バルーンＤにおいては測定点ｄにおいて円周方向の主屈折率が１．６４３とＰＥＴの固有屈折率１．６７４より小さい。
【００４８】
また、バルーンＡの円筒部と円錐部の境界近傍（測定部所ｂ点、ｃ点）の屈折率に注目すると、バルーンＡのｂ、ｃ点での円周方向、軸方向、厚さ方向の主屈折率はそれぞれ上記表２から抜粋した表６に示すようにｂ点、ｃ点で差が少なく、延伸状態がバルーンの円筒部と円錐部の境界近傍で均等であることが示されている。
【００４９】
【表６】
円周方向の複屈折率について示す。複屈折率（Δ）は延伸方向に平行な主屈折率（ｎ‖）と延伸方向に垂直な主屈折率（ｎ⊥）の差で表される。
Δ＝ｎ‖−ｎ⊥
それで、円周方向の複屈折率を求める場合、円周方向に垂直な主屈折率（ｎ⊥）として寄与の大きいと考えられる、軸方向（ｎｙ）、厚さ方向（ｎｚ）のうち値の大きい方を垂直成分の主屈折率として計算する方法と、軸方向、厚さ方向の平均を垂直成分にとる方法がある。
Δ＝ｎｘ−ｎｙ
Δ＝ｎｘ−ｎｚ
Δ＝ｎｘ−（ｎｙ＋ｎｚ）／２
これらのいずれの計算方法においても、本発明のバルーンＡにおける円周方向の複屈折率は、どの部所においても常に０より大きいことが表から読みとることができる。
【００５１】
バルーンＡと比べて、比較バルーンＢのｂ、ｃ点での円周方向、軸方向、厚さ方向の主屈折率は、それぞれ上記表３から抜粋した表７に示すように軸方向、厚さ方向の主屈折率の値の変動が大きく、バルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００５２】
【表７】
バルーンＡと比べて、比較バルーンＣのｂ、ｃ点での円周方向、軸方向、厚さ方向の主屈折率は、それぞれ上記表４から抜粋した表８に示すように円周方向、軸方向の主屈折率の値の変動が大きく、バルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００５４】
【表８】
バルーンＡと比べて、比較バルーンＤのｂ、ｃ点での円周方向、軸方向、厚さ方向の主屈折率は、それぞれ上記表５から抜粋した表９に示すように円周方向、軸方向、厚さ方向全ての主屈折率の値の変動が大きく、バルーンの円筒部と円錐部の境界近傍で一様な延伸状態では無いことが示されている。
【００５６】
【表９】
配向係数に関しても、本発明のバルーンＡは、円周方向、軸方向、厚さ方向の配向係数が比較バルーンＢ、Ｃ、Ｄと比べてバルーンの各部分で円周方向、軸方向、厚さ方向の配向係数の変動が少なく、延伸ムラが少ないことが示されている。
【００５８】
表２に示されているように、バルーンＡは各測定部所ａ、ｂ、ｃ、ｄのどの点においても配向係数の大きさが、円周方向＞軸方向＞厚さ方向の順になっており、配向が延伸を行った方向、すなわち円周方向、軸方向に存在し、主延伸方向である円周方向の配向がいちばん大きいことが示されている。また、各測定部所ａからｄでの配向係数の大きさは円周方向が０．４７６〜０．５９９と１／３より大きく、軸方向が０．３３３〜０．３５４、厚さ方向が０．０２７〜０．１９０と１／３より小さくなっており、また測定点間での差が小さくバルーン円筒部から円錐部にかけて延伸状態が一様であることが示されている。さらにバルーンの円筒部と円錐部の境界近傍（測定部所ｂ点、ｃ点）の配向係数に注目するとバルーンＡのｂ、ｃ点での円周方向、軸方向、厚さ方向の配向係数は、それぞれ上記表２から抜粋した表１０に示すようにｂ点、ｃ点で差が少なく、バルーンの円筒部と円錐部の境界近傍で延伸状態が均等であることが示されている。
【００５９】
【表１０】
バルーンＡと比べて、比較バルーンＢは測定部所ｄにおいて配向係数の大きさが厚さ方向＞円周方向＞軸方向となり、円周方向、軸方向の延伸がおこなわれていないことが示されており、各測定部所ａからｄの配向係数の大きさも円周方向が０．３３３〜０．５９９、軸方向が０．２９３〜０．３７４、厚さ方向が０．０６８〜０．３５４と測定点間での差がバルーンＡと比べて大きく、バルーン円筒部から円錐部にかけての延伸状態が一様でないことが示されている。また、バルーンＢのｂ、ｃ点での円周方向、軸方向、厚さ方向の配向係数はそれぞれ上記表３から抜粋した表１１に示すように軸方向、厚さ方向の配向係数の値の変動が大きく、バルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００６１】
【表１１】
バルーンＡと比べて、比較バルーンＣは測定部所ｄにおいて配向係数の大きさが厚さ方向＞円周方向＞軸方向となり、しかもそれぞれの値が０．３３３に近いことからどの方向に対してもほとんど延伸がおこなわれていないことが示されている。また、バルーンＣのｂ、ｃ点での円周方向、軸方向、厚さ方向の分子配向係数はそれぞれ上記表４から抜粋した表１１に示されるように円周方向、軸方向の分子配向係数の変動が大きく、バルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００６３】
【表１２】
バルーンＡと比べて、比較バルーンＤは測定部所ｄにおいて配向係数の大きさが厚さ方向＞円周方向＞軸方向となり、円周方向、軸方向の延伸がおこなわれていないことが示されており、各測定部所ａからｄの配向係数の大きさも円周方向が０．３０６〜０．４７６、軸方向が０．２７３〜０．４２５、厚さ方向が０．０９８〜０．４２１と測定点間での差がバルーンＡと比べて大きく、バルーン円筒部から円錐部にかけての延伸状態が一様でないことが示されている。また、バルーンＤのｂ、ｃ点での円周方向、軸方向、厚さ方向の配向係数はそれぞれ上記表５から抜粋した表１３に示されるように円周方向、軸方向、厚さ方向全ての配向係数の変動が大きく、バルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００６５】
【表１３】
配向度に関しても、本発明のバルーンＡは、円周方向、軸方向、厚さ方向の配向度が比較バルーンＢ、Ｃ、Ｄと比べてバルーンの各部分で円周方向、軸方向、厚さ方向の配向度の変動が少なく、延伸ムラが少ないことが示されている。具体的に示すと、バルーンＡは各測定部所ａ、ｂ、ｃ、ｄのどの点においても円周方向の分子配向度の値が０より大きくなっており、配向が延伸を行った方向すなわち円周方向に存在することが示されている。また、各測定部所ａからｄでの配向度の大きさは円周方向が０．２１４〜０．３９８、軸方向が０．０００〜０．０３１、厚さ方向が−０．４５９〜−０．２１４と測定点間での差が小さく、かつ円周方向の配向度が常に０より大きく、軸方向の配向度が常に０に近く、厚さ方向の配向度が常に０より小さいことからバルーン円筒部から円錐部にかけて延伸状態が一様であることが示されている。さらにバルーンの円筒部と円錐部の境界近傍（測定部所ｂ点、ｃ点）の配向度に注目するとバルーンＡのｂ、ｃ点での円周方向、軸方向、厚さ方向の配向度はそれぞれ上記表２から抜粋した表１４に示すようにｂ点、ｃ点で各方向の分子配向度に差が少なく、バルーンの円筒部と円錐部の境界近傍で延伸状態が均等であることが示されている。
【００６７】
【表１４】
バルーンＡと比べて、比較バルーンＢは測定部所ｄにおいて円周方向の配向度が０であり円周方向の延伸がおこなわれていないことが示されており、各測定部所ａからｄの配向度の大きさも円周方向が０．０００〜０．３９８、軸方向が−０．０６１〜０．０６１、厚さ方向が−０．３９８〜０．０３１と測定点間での差がバルーンＡと比べ大きく、バルーン円筒部から円錐部にかけての延伸状態が一様でないことが示されている。また、バルーンＢのｂ、ｃ点での円周方向、軸方向、厚さ方向の配向度はそれぞれ上記表３から抜粋した表１５に示されるように軸方向、厚さ方向の配向度の値の変動が大きくバルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００６９】
【表１５】
バルーンＡと比べて、比較バルーンＣは測定部所ｄにおいて円周方向の配向度が０であり円周方向の延伸がおこなわれていないことが示されており、各測定部所ａからｄの配向度の大きさも円周方向が０．０００〜０．３０６、軸方向が−０．０３１〜０．０９２、厚さ方向が−０．３３７〜０．０３１と測定部所間での差がバルーンＡと比べて大きく、バルーン円筒部から円錐部にかけての延伸状態が一様でないことが示されている。また、バルーンＣのｂ、ｃ点での円周方向、軸方向、厚さ方向の配向度はそれぞれ上記表４から抜粋した表１６に示されるように軸方向、厚さ方向の分子配向度の値の変動が大きくバルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００７１】
【表１６】
バルーンＡと比べて、比較バルーンＤは測定点ｄにおいて円周方向の配向度が０より小さく、円周方向の延伸がおこなわれていないことが示されており、各測定部所ａからｄの配向度の大きさも円周方向が−０．０４１〜０．２１４、軸方向が−０．０９０〜０．１３８、厚さ方向が−０．３５３〜０．１３１と測定点間での差がバルーンＡと比べて大きく、バルーン円筒部から円錐部にかけての延伸状態が一様でないことが示されている。また、バルーンＤのｂ、ｃ点での円周方向、軸方向、厚さ方向の配向度はそれぞれ上記表５から抜粋した表１７に示されるように円周方向、軸方向、厚さ方向全ての配向度の値の変動が大きくバルーンの円筒部と円錐部の境界近傍で一様な延伸状態ではないことが示されている。
【００７３】
【表１７】
（３）膜強度
本発明のバルーンＡ、比較バルーンＢ、Ｃの破壊試験を実施した。そのデータとそれから求めた膜強度を表１８に示す。破壊試験はカテーテル内部に３７℃生理食塩水を徐々に導入していくのと同時に、バルーン部の外径と内圧をバルーン部が破壊するまで測定した。バルーンが破壊する圧力を本明細書中では破壊圧力とする。円筒状の物に内部から圧が加わる場合は円周方向に加わる応力は軸方向に加わる応力の２倍であり、試験したバルーンは全て円周方向に引っ張られて破壊されていた。バルーン管壁の強度は下記に示すように公知の薄肉円管の円周方向の応力方程式：ｆ＝ｐｄ／２ｔから求めた。膨張による管壁厚の変化は無いものとして計算した。
ｆは管壁の円周方向の強度
ｐは加えられた内圧
ｄは直径
ｔは管壁厚
【００７５】
【表１８】
表１８から明かなように、バルーンＡの破壊圧力、膜強度は共に比較バルーンＢ、Ｃを上回った。比較バルーンＢの破壊は、円筒部、円錐部の境界近傍で始まるものが多かった。
【００７７】
【発明の効果】
本発明のカテーテル用バルーンは、円筒部とその両端に外側に向かい径小に傾斜する円錐部分を持つ円筒部を有するカテーテル用バルーンであって、両方又は一方の円筒部と円錐部の肉厚の比が円筒部を形成される前のチューブとの比より比較的小で、両方又は一方の円筒部から円錐部にかけて延伸ムラ、配向ムラの少ないことが特徴である。特に、円筒部の円錐部近傍における十分に延伸されにくい部分の延伸が的確に行われて配向ムラが無くなるので、成型品としての強度が向上し、また強度が向上した分だけ薄肉化されたバルーンを提供することが可能である。
本発明のバルーンは、ブロー成形の際にチューブを軸方向へバルーンの反対方向に移動させることにより得られ、従来方法、即ち、予めチューブを予備的に加工しておくような操作が必要であったり、バルーン円筒部を積層化するような煩雑な操作が必要な方法に比べ、容易にバルーン円筒部と円錐部の肉厚をコントロールすることが可能である。
【図面の簡単な説明】
【図１】 本発明のバルーン製造装置を示す概略図である。
【図２】 バルーンの円周方向（ｎｘ）、軸方向（ｎｙ）、厚さ方向（ｎｚ）の主屈折率を示す図である。
【図３】 図３はバルーンの主屈折率等の測定部位を示す図である。
【符号の説明】
１ チューブ
２ 型
３ パリソン
４ 検知手段
５、６ 固定部
７ スライドテーブル
８ 圧力気体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catheter used in an operation for an expansion operation and a manufacturing method thereof, and more particularly to a vasodilation catheter.
[0002]
[Prior art]
Dilatation catheters are used for angioplasty treatments for stenotic or occluded blood vessels. In this treatment, the balloon part of the catheter must be inserted into the stenotic site via the patient's artery, so that the balloon part has a small cross section (low profile), and the catheter tip including the balloon part is a blood vessel. It is required to have excellent followability, that is, high flexibility and low friction with the guide wire. In order to satisfy both of these requirements, the thinning of the balloon portion has been studied. As shown in Japanese Patent Publication No. 63-26655 and Japanese Patent Publication No. 3-63908, a balloon molding method used for a conventional vasodilator catheter for the purpose of reducing the thickness of the balloon is obtained by changing the balloon raw material parison to a secondary transition temperature or higher. In FIG. 1, a high-strength balloon stretched in the axial direction and then blow-molded in a mold to be stretched in the circumferential direction and secondarily stretched was obtained.
[0003]
In general, when forming a balloon, it is inevitable that the thickness of the conical portion of the balloon obtained by the above-described method becomes thicker than the thickness of the cylindrical portion as the distance from the cylindrical portion increases. For this reason, when the balloon is deflated for insertion into the blood vessel and folded around the shaft, it is difficult to fold because the thickness of the cone is thick, or the section of the folded cone is more than the cross section of the nearby catheter. In some cases, the size of the balloon became larger and a protrusion was formed at the end of the balloon. Therefore, the ability of the catheter to pass through the blood vessel and the ability to break through the stenosis are reduced, and there is also a risk that the inserted blood vessel and other tissues are damaged.
[0004]
In order to solve these problems, a method of manufacturing a balloon in which a portion considered to form a conical portion of a parison is selectively thinned in advance and the thickness of the conical portion is controlled to be thin (Japanese Patent Laid-Open No. 2387 / 4-176473), and a balloon (Japanese Patent Laid-Open No. 4-231070) in which a balloon cylindrical portion is multilayered and a conical portion is thinned has been proposed.
[0005]
[Problems to be solved by the invention]
In order to produce the balloon portion of the medical catheter as described above, many efforts have been made to increase the strength, reduce the thickness, decrease the thickness ratio of the cylindrical portion and the conical portion, and so on. However, in the process of studying balloon fabrication, especially when examining the fracture characteristics of balloons in detail, balloons fabricated with conventional technology often break from the vicinity of the transition from the cylindrical part to the conical part. I realized that. As a result of further investigation of the cause, it was found that the balloon produced by the conventional technique has uneven molecular orientation in the vicinity of the transition portion from the cylindrical portion to the conical portion and in the conical portion.
[0006]
As described above, the dilatation catheter balloon is fabricated by biaxial stretching. Stretching is a process in which a polymer material is pulled at a temperature above the softening point to orient the molecules and increase the strength. In stretching, it is essential that a uniform temperature, stress, and amount of stretching be maintained in any part of the material. Regarding the temperature, if the material is stretched in a state where it has not been sufficiently softened, the stress becomes non-uniform and stretching unevenness occurs.If the temperature is too high, the temperature dependence of orientation relaxation during stretching increases, and slight temperature unevenness causes uneven orientation. It becomes. With regard to stress and stretching amount, film stretching using a tenter or the like applies a uniform stress and stretching amount within the film material, but when stretching in the mold, the stress and stretching applied to the material due to the shape in the mold Since the amount is not constant, it is difficult for the entire material to be in a uniform stretched state. In the case of a balloon, since it is stretched and blown in a mold composed of a cylindrical part and a conical part, it is clear that the degree of stretching differs between the cylindrical part and the conical part, and uneven stretching tends to occur. The balloon part is made with high strength by highly stretching the polymer material, but if the orientation by stretching is not aligned, the strength of that part naturally decreases, so it becomes thick to increase the pressure resistance as a balloon. It was. Therefore, the strength as a molded product can be increased by uniformly stretching and eliminating the orientation unevenness due to the balloon portion, and the thickness can be reduced by the amount of the increased strength.
[0007]
Further, as described above, it is considered important to reduce the thickness of the balloon cone, but for this purpose, an operation in which the tube is preliminarily processed as disclosed in Japanese Patent Laid-Open No. 2-4387. Or a complicated operation of stacking the balloon cylindrical portion as disclosed in JP-A-4-231030. .
[0008]
The present invention provides a catheter balloon in which the unevenness in orientation of the balloon cylindrical portion and the cone portion is eliminated, the pressure resistance is further improved, and the balloon portion is thinned, and a method for manufacturing the same. Furthermore, the present invention provides a catheter balloon in which the difference in wall thickness between the balloon cylindrical portion and the cone portion is reduced, and an easy manufacturing method of the catheter balloon.
[0009]
[Means for Solving the Problems]
The present invention relates to a catheter balloon having a cylindrical portion and conical portions inclined at a small diameter toward the outside at both ends thereof, before the ratio of the thickness of both or one cylindrical portion and the conical portion is formed into the cylindrical portion. Molecular orientation in the main stretching direction (circumferential direction), especially in the catheter balloon, characterized in that it is relatively smaller than the tube ratio, and both or one of them has little stretching unevenness and uneven orientation from the cylindrical part to the conical part. The above object is achieved by providing a dilatation catheter balloon characterized in that the non-uniformity is relatively small in the cylindrical portion, in the vicinity of the boundary between the cylindrical portion and the conical portion, and in the conical portion.
[0010]
That is, the first of the present invention is Stretching is possible A catheter balloon formed of a polymer material and having a cylindrical portion and conical portions inclined at a small diameter toward the outside at both ends of the cylindrical portion, the main refractive index in the circumferential direction from both the cylindrical portion to the conical portion It is intended to include a dilatation catheter balloon characterized in that is always greater than the intrinsic refractive index of the material forming the balloon and the circumferential birefringence is always greater than zero.
[0011]
The second of the present invention is Stretching is possible A catheter balloon formed of a polymer material and having a cylindrical portion and conical portions inclined at a small diameter toward the outside at both ends thereof, and the circumferential orientation coefficient from the cylindrical portion to the conical portion of either or one of them is The contents of the catheter balloon for dilatation are characterized in that it is always larger than 1/3 at the cylindrical part, the vicinity of the boundary between the cylindrical part and the conical part, and the conical part.
[0012]
The third aspect of the present invention is Stretching is possible A catheter balloon formed of a polymer material and having a cylindrical portion and conical portions inclined at a small diameter toward the outside at both ends thereof, the degree of circumferential orientation from both the cylindrical portion to the conical portion is The contents of the catheter balloon for expansion are characterized by being always greater than zero at the cylindrical portion, near the boundary between the cylindrical portion and the conical portion, and at the conical portion.
[0013]
The fourth aspect of the present invention is Stretching is possible A catheter balloon which is formed of a polymer material and has a cylindrical portion and conical portions inclined at a small diameter toward the outside at both ends thereof, and both or one of them has an orientation coefficient in the film thickness direction from the cylindrical portion to the conical portion. The content of the catheter balloon for expansion is characterized by being always smaller than 1/3 at the cylindrical portion, the vicinity of the boundary between the cylindrical portion and the conical portion, and the conical portion.
[0014]
The fifth aspect of the present invention is Stretching is possible A catheter balloon formed of a polymer material and having a cylindrical portion and conical portions inclined at a small diameter toward the outside at both ends thereof, and the degree of orientation in the film thickness direction from the cylindrical portion to the conical portion of both or one The content of the catheter balloon is a cylindrical portion, a portion near the boundary between the cylindrical portion and the conical portion, and a conical portion that is always smaller than 0.
[0015]
The sixth of the present invention is Stretching is possible A catheter balloon formed of a polymer material having a negative refractive index and having a conical portion that is inclined outwardly with a small diameter at both ends of the cylindrical portion, and the circumference of both or one of the cylindrical portion from the cylindrical portion to the conical portion The dilatation catheter balloon is characterized in that the principal refractive index in the direction is always smaller than the intrinsic refractive index of the material forming the balloon and the birefringence in the circumferential direction is always smaller than zero.
[0016]
The seventh of the present invention is Stretching is possible The tube-shaped parison made of a polymer material is stretched in the circumferential direction in the mold at a temperature equal to or higher than the second-order transition temperature, and at the same time, the formation of the balloon is started. A catheter balloon having a cylindrical portion and conical portions which are inclined toward the outside toward the outside at both ends thereof, obtained by moving both sides or the outside of the outer tube in the axial direction opposite to the balloon. An extension characterized in that the principal refractive index in the circumferential direction from the cylindrical part to the conical part is always larger than the intrinsic refractive index of the material forming the balloon, and the birefringence in the circumferential direction is always greater than zero. Contains catheter balloon.
[0017]
The eighth of the present invention is Stretching is possible The tube-shaped parison made of a polymer material is stretched in the circumferential direction in the mold at a temperature equal to or higher than the second-order transition temperature, and at the same time, the formation of the balloon is started. A catheter balloon having a cylindrical portion and conical portions which are inclined toward the outside toward the outside at both ends thereof, obtained by moving both sides or the outside of the outer tube in the axial direction opposite to the balloon. The dilatation catheter balloon is characterized in that the orientation coefficient in the circumferential direction from the cylindrical portion to the conical portion is always greater than 1/3 at the cylindrical portion, the vicinity of the boundary between the cylindrical portion and the conical portion, and the conical portion. To do.
[0018]
The ninth of the present invention is Stretching is possible The tube-shaped parison made of a polymer material is stretched in the circumferential direction in the mold at a temperature equal to or higher than the second-order transition temperature, and at the same time, the formation of the balloon is started. A catheter balloon having a cylindrical portion and conical portions which are inclined toward the outside toward the outside at both ends thereof, obtained by moving both sides or the outside of the outer tube in the axial direction opposite to the balloon. The expandable catheter balloon is characterized in that the degree of orientation in the circumferential direction from the cylindrical portion to the conical portion is always greater than 0 in the cylindrical portion, the vicinity of the boundary between the cylindrical portion and the conical portion, and the conical portion.
[0019]
The tenth aspect of the present invention is Stretching is possible The tube-shaped parison made of a polymer material is stretched in the circumferential direction in the mold at a temperature equal to or higher than the second-order transition temperature, and at the same time, the formation of the balloon is started. A catheter balloon having a cylindrical portion and conical portions which are inclined toward the outside toward the outside at both ends thereof, obtained by moving both sides or the outside of the outer tube in the axial direction opposite to the balloon. The dilatation catheter balloon is characterized in that the orientation coefficient in the film thickness direction from the cylindrical portion to the conical portion is always smaller than 1/3 at the cylindrical portion, near the boundary between the cylindrical portion and the conical portion, and at the conical portion. To do.
[0020]
The eleventh aspect of the present invention is Stretching is possible The tube-shaped parison made of a polymer material is stretched in the circumferential direction in the mold at a temperature equal to or higher than the second-order transition temperature, and at the same time, the formation of the balloon is started. A catheter balloon having a cylindrical portion and conical portions which are inclined toward the outside toward the outside at both ends thereof, obtained by moving both sides or the outside of the outer tube in the axial direction opposite to the balloon. The dilatation catheter balloon is characterized in that the degree of orientation in the film thickness direction from the cylindrical portion to the conical portion is always smaller than 0 in the cylindrical portion, in the vicinity of the boundary between the cylindrical portion and the conical portion, and in the conical portion. .
[0021]
The twelfth aspect of the present invention is Stretching is possible A tube-shaped parison made of a polymer material having a negative refractive index is stretched in the mold in the circumferential direction above the second-order transition temperature to start balloon formation. At the same time, the stress applied to the tube-shaped parison in the axial direction is reduced. A catheter balloon having a conical portion that is inclined toward the outside toward the outside at both ends of the cylindrical portion, obtained by axially moving both sides or the outside of the tube of the outer portion of the mold in accordance with the change in the axial direction. The main refractive index in the circumferential direction is always smaller than the intrinsic refractive index of the material forming the balloon, and the birefringence in the circumferential direction is always smaller than 0, both or one from the cylindrical portion to the conical portion. A dilatation catheter balloon characterized by:
[0022]
The thirteenth aspect of the present invention is Stretching is possible When forming a catheter balloon by placing a tubular parison made of a polymer material in the mold and blowing a pressure gas above the second-order transition temperature, the tubular parison stretches in the circumferential direction and starts forming the balloon at the same time. Detecting a change in stress applied in the axial direction of the parison, and performing an operation of moving both sides or one side of the external tube of the mold in the axial direction to the opposite side of the balloon in accordance with the change in the stress. The manufacturing method of the catheter balloon for expansion | swelling to make is content.
[0023]
The catheter balloon of the present invention is manufactured using, for example, an apparatus as shown in FIG. That is, a tube 1 having a material, diameter, and thickness suitable for forming into a balloon is introduced into the mold 2, the
In a preferred embodiment of the present invention, a balloon is obtained that is in a substantially constant stretched state from the balloon cylinder to the cone. In particular, the portion of the cylindrical portion in the vicinity of the conical portion that is not sufficiently stretched is accurately stretched to eliminate alignment unevenness. In addition, the thickness of the conical portion of the balloon of the present invention is smaller than that in the case where the operation of moving the tube in the axial direction is not performed during blow molding, and the ratio to the thickness of the cylindrical portion is relatively small. Become.
[0024]
The balloon portion used for the dilatation catheter is made by stretching to give sufficient strength against the internal pressure applied during dilatation. The polymer material exhibits anisotropy in mechanical properties, optical properties, thermal properties, and electrical properties due to stretching. Such anisotropy of physical properties is governed by the orientation of polymer chains intervening in the crystalline and amorphous phases due to stretching. Therefore, the molecular orientation can be evaluated by evaluating the anisotropy.
[0025]
The material of the balloon part can be selected without limitation as long as it is a polymer material that can be stretched. For example, polyethylene, polypropylene, polyester, polyurethane, polyamide, polyethylene terephthalate, polystyrene, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyimide, Polymer materials such as polyacetylene and polysulfone, and copolymers and mixtures thereof are applicable. They can evaluate the stretched state as the molecular orientation in the material by using the following various evaluation methods in accordance with the characteristics of the material.
[0026]
In general, a stretched polymer is evaluated for orientation by various spectroscopic techniques. Specifically, there are orientation evaluation by birefringence measurement method using micro-polarization spectrophotometer or refractometer, wide-angle X-ray diffraction, small-angle X-ray scattering, modified fluorescence method, laser Raman scattering method. Is expressed by the orientation coefficient and the degree of orientation. The orientation coefficient is the mean square value of the direction cosines of the orientation of the molecular chain and crystal main axis (total molecular orientation) with respect to the stretching direction as shown in (a) below, and the degree of orientation can be obtained from this as shown in (b) below. . When the molecular chain and the crystal are completely oriented in the stretching direction, the result is as shown in (c) below. When the orientation has no directionality, it is as shown in (d) below. When it is oriented completely perpendicular to the stretching direction, it is as shown in (e) below. That is, when the orientation coefficient is greater than 1/3 and the degree of orientation is greater than 0, orientation exists in the stretching direction, and when the orientation coefficient is less than 1/3 and the orientation degree is less than 0, the orientation perpendicular to the stretching direction is present. Indicates that it exists.
[0027]
[Expression 1]
In ideal stretching of a polymer film, molecular chains and crystal main axes are oriented in parallel to the stretching direction, so that the orientation coefficient in the stretching direction is always greater than 1/3, the degree of orientation is greater than 0, and the film thickness Since the direction is perpendicular to the stretching direction and the molecular orientation parallel thereto, the orientation coefficient is always smaller than 1/3 and the degree of orientation is smaller than zero.
[0029]
In this specification, since molecular orientation is evaluated by measuring refractive index, the relationship between stretching and refractive index will be described in more detail. The refractive index of a substance originates from the polarization of the molecule, and most molecules are polarized. Therefore, it is optically anisotropic. When molecules in a material are randomly distributed without showing directionality, polarizabilities in all directions are equal and a single refractive index is shown. When the is oriented, optical anisotropy appears. In the stretching of the polymer film, particularly biaxial stretching, the refractive index of light oscillating in the length, width, and thickness directions is different, and the main refractive index is set in three directions. In that case, since the molecular chain and the crystal main axis are oriented parallel to the stretching direction, the main refractive index in the stretching direction is always larger than the intrinsic refractive index of the material, and the birefringence is larger than zero.
[0030]
As the balloon material, as described above, a stretchable polymer material, a copolymer, and a mixture thereof can be applied. For example, polystyrene, polymethyl methacrylate, a copolymer, and a mixture thereof can be used. It should be noted that when the orientation direction and the optical axis are perpendicular, that is, a material having a negative refractive index is opposite to a material having a positive refractive index.
[0031]
In this specification, a micro-polarization spectrophotometer was used to measure the main refractive index and birefringence of the balloon in the circumferential direction, axial direction, and film thickness direction. 78-81, Convertec October 1994, p. 63-67, Convertec December 1994, p. 44-47, Convertec January 1995, p. 4-8, Convertec February 1995, p. The orientation coefficient and orientation degree of each direction of the balloon were obtained by the method described in 33 to 35 and used as evaluation indices.
[0032]
Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
[0033]
【Example】
Example 1
A cross-linked polyethylene tube having a diameter and thickness suitable for forming into a balloon is placed in a mold having an inner diameter of 2.5 mmφ, heated to 115 ° C., and stretched 1.5 times in the axial direction. Pressurized nitrogen (6kg / cm 2 ) Is detected using a force gauge, and at the same time, both ends of the tube are quickly moved axially in the opposite direction of the balloon at a speed of 400 mm / sec. A 2.5 mm balloon was formed (balloon A).
[0034]
Comparative Example 1
A balloon (balloon B) having an outer diameter of 2.5 mm was formed in the same manner as in Example 1 except that the operation of moving both ends of the tube in the axial direction toward the opposite direction of the balloon was not performed.
[0035]
Comparative Examples 2 and 3
A commercially available polyethylene catheter balloon (balloon C) having a nominal outer diameter of 2.5 mm and a commercially available catheter balloon (balloon D) made of polyethylene terephthalate (PET) were used for comparison.
[0036]
The balloons A to D were measured for thickness, main refractive index, orientation coefficient, and orientation degree. FIG. 3 shows portions of the balloon where the wall thickness, main refractive index, etc. were measured. a is the center of the cylindrical part of the balloon, b is a part 0.5 mm from the boundary between the balloon cylindrical part and the conical part to the cylindrical part side, c is 0.5 mm from the boundary between the balloon cylindrical part and the conical part to the conical part side The part, d is the center of the balloon cone.
[0037]
(1) Balloon thickness
The thickness of the balloon A of the present invention and the balloon B of Comparative Example 1 was measured at each of the measurement points a to d shown in FIG. The results are as follows.
[0038]
[Table 1]
The wall thickness of the balloon A at the point d, which is the center of the cone portion, is smaller than that of the balloon B. When the balloon A is folded around the shaft portion, the balloon A is easier to fold than the balloon B. Balloon A was smaller.
[0040]
(2) Main refractive index, orientation coefficient, orientation degree
For the balloons A to D, as shown in FIG. 2, the main refractive index, molecular orientation coefficient, and molecular orientation degree in the circumferential direction (nx), axial direction (ny), and thickness direction (nz) are shown in FIG. Measurements were taken at the measurement site. A measurement result is shown as a calculation result.
As a measuring method, the retardation of the balloon portion was measured using a micro-polarization spectrophotometer, and the main refractive index, molecular orientation coefficient, and molecular orientation degree in the balloon circumferential direction, axial direction, and thickness direction were calculated. The calculation used 1.510 as the intrinsic refractive index of polyethylene, 0.049 as the intrinsic birefringence, 1.675 as the intrinsic refractive index of PET, and 0.217 as the intrinsic birefringence.
[0041]
[Table 2]
[Table 3]
[Table 4]
[Table 5]
As can be seen from these tables, the balloon A of the present invention has a main refractive index, an orientation coefficient, and an orientation degree in the circumferential direction, the axial direction, and the thickness direction in each part of the balloon as compared with the comparative balloons B, C, and D. Fluctuation is small and stretching unevenness is small.
In particular, it can be seen that in comparative balloons B, C, and D, the main refractive index, the orientation coefficient, and the orientation degree fluctuate greatly near the boundary between the cylindrical portion and the conical portion of the balloon, and the stretching is uneven.
[0046]
In comparison balloons B, C, and D, there is a portion where no molecular orientation is observed near the boundary between the cylindrical portion and the conical portion, and almost no orientation is observed at the central portion d of the conical portion. Regarding the refractive index, it can be seen that the balloon A of the present invention always has a circumferential refractive index larger than the intrinsic refraction at any measurement location, and always has a circumferential orientation.
Further, in comparative balloons B, C, and D, the refractive index in the circumferential direction is the same as the intrinsic refractive index, that is, there is no molecular orientation in the circumferential direction compared to other directions, or the refractive index in the circumferential direction is unique. It is smaller than the refractive index and is oriented in the other direction rather than the molecular orientation in the circumferential direction.
[0047]
Specifically, the balloon A shows a value in which the main refractive index in the circumferential direction is larger than the intrinsic refractive index 1.510 at any of the measurement points a, b, c, and d, and the circumferential direction> axis Direction> thickness direction relationship is shown, but the comparison balloons B, C, and D do not satisfy the above relationship, and the main refractive index in the circumferential direction at the measurement point d is both balloons B and C. It is not greater than 1.510 and the intrinsic refractive index 1.510. In the balloon D, the main refractive index in the circumferential direction at the measurement point d is 1.463, which is smaller than the intrinsic refractive index of PET 1.673.
[0048]
When attention is paid to the refractive index in the vicinity of the boundary between the cylindrical part and the conical part of the balloon A (measurement points b and c), the circumferential direction, the axial direction, and the thickness direction at the points b and c of the balloon A As shown in Table 6 excerpted from Table 2 above, the main refractive index has little difference at points b and c, indicating that the stretched state is uniform near the boundary between the cylindrical portion and the conical portion of the balloon. .
[0049]
[Table 6]
The birefringence in the circumferential direction will be described. The birefringence (Δ) is represented by the difference between the main refractive index (n‖) parallel to the stretching direction and the main refractive index (n⊥) perpendicular to the stretching direction.
Δ = n‖−n⊥
Therefore, when obtaining the birefringence index in the circumferential direction, the value of the axial direction (ny) or the thickness direction (nz) is considered to have a large contribution as the main refractive index (n⊥) perpendicular to the circumferential direction. There are a method of calculating the larger one as the main component refractive index of the vertical component and a method of taking the average in the axial direction and the thickness direction as the vertical component.
Δ = nx−ny
Δ = nx−nz
Δ = nx− (ny + nz) / 2
In any of these calculation methods, it can be read from the table that the birefringence index in the circumferential direction in the balloon A of the present invention is always greater than 0 at any part.
[0051]
Compared with the balloon A, the principal refractive indexes in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the comparative balloon B are respectively the axial direction and thickness as shown in Table 7 extracted from Table 3 above. The variation in the value of the main refractive index in the direction is large, indicating that the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0052]
[Table 7]
Compared with the balloon A, the principal refractive indexes in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the comparative balloon C are shown in Table 8 extracted from Table 4 above. The variation in the value of the main refractive index in the direction is large, indicating that the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0054]
[Table 8]
Compared to the balloon A, the principal refractive indexes in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the comparative balloon D are shown in Table 9 extracted from Table 5 above. The fluctuations in the values of the main refractive index in all directions and in the thickness direction are large, indicating that the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0056]
[Table 9]
Regarding the orientation coefficient, the balloon A of the present invention has an orientation coefficient in the circumferential direction, the axial direction, and the thickness direction in the circumferential direction, the axial direction, and the thickness in each part of the balloon as compared with the comparative balloons B, C, and D. It is shown that there is little fluctuation in the orientation coefficient in the direction and there is little stretching unevenness.
[0058]
As shown in Table 2, the size of the orientation coefficient of the balloon A is in the order of circumferential direction> axial direction> thickness direction at any of the measurement points a, b, c, d. It is shown that the orientation is present in the direction of stretching, that is, the circumferential direction and the axial direction, and the orientation in the circumferential direction, which is the main stretching direction, is the largest. In addition, the size of the orientation coefficient at each measurement point a to d is 0.476 to 0.599 in the circumferential direction, which is larger than 1/3, the axial direction is 0.333 to 0.354, and the thickness direction is It is 0.027 to 0.190, which is smaller than 1/3, and the difference between the measurement points is small, indicating that the stretched state is uniform from the balloon cylindrical portion to the conical portion. Further, when attention is paid to the orientation coefficient in the vicinity of the boundary between the cylindrical portion and the conical portion of the balloon (measurement points b and c), the orientation factors in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the balloon A are as follows. As shown in Table 10 extracted from Table 2 above, there is little difference between the points b and c, indicating that the stretched state is uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0059]
[Table 10]
Compared to the balloon A, the comparative balloon B has a thickness direction> circumferential direction> axial direction at the measurement part d, and it is shown that the circumferential direction and the axial direction are not stretched. The orientation coefficients of the measurement points a to d are 0.333 to 0.599 in the circumferential direction, 0.293 to 0.374 in the axial direction, and 0.068 to 0.354 in the thickness direction. And the difference between the measurement points is larger than that of the balloon A, indicating that the stretched state from the balloon cylindrical portion to the conical portion is not uniform. Further, the orientation coefficients in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the balloon B are the values of the orientation coefficients in the axial direction and the thickness direction, respectively, as shown in Table 11 extracted from Table 3 above. It is shown that the fluctuation is large and the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0061]
[Table 11]
Compared with the balloon A, the comparative balloon C has a thickness direction> circumferential direction> axial direction at the measurement point d, and the respective values are close to 0.333. It is also shown that almost no stretching has been performed. Further, the molecular orientation coefficients in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the balloon C are respectively shown in Table 11 extracted from Table 4 above. It is shown that there is a large variation in the angle, and the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0063]
[Table 12]
Compared to the balloon A, the comparative balloon D has a size of the orientation coefficient in the thickness direction> circumferential direction> axial direction in the measurement part d, and it is shown that the circumferential direction and the axial direction are not stretched. The orientation coefficients of the measurement points a to d are also 0.306 to 0.476 in the circumferential direction, 0.273 to 0.425 in the axial direction, and 0.098 to 0.421 in the thickness direction. And the difference between the measurement points is larger than that of the balloon A, indicating that the stretched state from the balloon cylindrical portion to the conical portion is not uniform. Further, the orientation coefficients in the circumferential direction, the axial direction, and the thickness direction at points b and c of the balloon D are all shown in Table 13 extracted from Table 5 above. The variation in the orientation coefficient is large, indicating that the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0065]
[Table 13]
Regarding the degree of orientation, the balloon A of the present invention has a degree of orientation in the circumferential direction, the axial direction, and the thickness direction in each part of the balloon as compared with the comparative balloons B, C, and D. It is shown that there is little variation in the degree of orientation in the direction, and there is little stretching unevenness. Specifically, in the balloon A, the value of the degree of molecular orientation in the circumferential direction is greater than 0 at any point of each measurement location a, b, c, d, and the orientation is the direction in which the orientation has been performed, It is shown to exist in the circumferential direction. Further, the degree of orientation at each measurement site a to d is 0.214 to 0.398 in the circumferential direction, 0.000 to 0.031 in the axial direction, and −0.459 to − in the thickness direction. The difference between 0.214 and the measurement point is small, the degree of orientation in the circumferential direction is always greater than 0, the degree of orientation in the axial direction is always close to 0, and the degree of orientation in the thickness direction is always less than 0. It is shown that the stretched state is uniform from the balloon cylindrical part to the conical part. Further, when attention is paid to the degree of orientation in the vicinity of the boundary between the cylindrical portion and the conical portion of the balloon (measurement points b and c), the degrees of orientation in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the balloon A are as follows. As shown in Table 14 extracted from Table 2 above, there is little difference in the degree of molecular orientation in each direction at points b and c, indicating that the stretched state is uniform in the vicinity of the boundary between the cylindrical portion and the conical portion of the balloon. Has been.
[0067]
[Table 14]
Compared to balloon A, comparative balloon B shows that the degree of orientation in the circumferential direction is 0 at the measurement location d and that no circumferential stretching has been performed. The degree of orientation is 0.000 to 0.398 in the circumferential direction, -0.061 to 0.061 in the axial direction, and -0.398 to 0.031 in the thickness direction. It is larger than A and shows that the stretched state from the balloon cylindrical portion to the conical portion is not uniform. In addition, the degrees of orientation in the circumferential direction, the axial direction, and the thickness direction at points b and c of the balloon B are values of the degree of orientation in the axial direction and the thickness direction as shown in Table 15 extracted from Table 3 above. It is shown that there is a large variation in the distance between the cylindrical portion and the conical portion of the balloon and that the stretched state is not uniform.
[0069]
[Table 15]
Compared to the balloon A, the comparative balloon C shows that the degree of orientation in the circumferential direction is 0 at the measurement point d and the circumferential direction is not stretched. The degree of orientation is 0.000 to 0.306 in the circumferential direction, -0.031 to 0.092 in the axial direction, and -0.337 to 0.031 in the thickness direction. It is larger than the balloon A, and it is shown that the stretched state from the balloon cylindrical portion to the cone portion is not uniform. Further, the degrees of orientation in the circumferential direction, the axial direction, and the thickness direction at points b and c of the balloon C are shown in Table 16 extracted from Table 4 above, respectively. It is shown that the fluctuation of the value is large and the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0071]
[Table 16]
Compared to the balloon A, the comparative balloon D has a degree of orientation in the circumferential direction smaller than 0 at the measurement point d, and it is shown that the stretching in the circumferential direction is not performed. The degree of orientation is -0.041 to 0.214 in the circumferential direction, -0.090 to 0.138 in the axial direction, and -0.353 to 0.131 in the thickness direction. It is larger than the balloon A, and it is shown that the stretched state from the balloon cylindrical portion to the cone portion is not uniform. Further, the degrees of orientation in the circumferential direction, the axial direction, and the thickness direction at the points b and c of the balloon D are all in the circumferential direction, the axial direction, and the thickness direction as shown in Table 17 extracted from Table 5 above. It has been shown that the degree of orientation value fluctuates greatly and the stretched state is not uniform near the boundary between the cylindrical portion and the conical portion of the balloon.
[0073]
[Table 17]
(3) Film strength
Destructive testing was performed on the balloon A of the present invention and the comparative balloons B and C. The data and the film strength determined from the data are shown in Table 18. In the destructive test, 37 ° C. physiological saline was gradually introduced into the catheter, and at the same time, the outer diameter and the internal pressure of the balloon were measured until the balloon was broken. The pressure at which the balloon breaks is referred to as the breaking pressure in this specification. When pressure was applied to the cylindrical object from the inside, the stress applied in the circumferential direction was twice the stress applied in the axial direction, and all the balloons tested were pulled and broken in the circumferential direction. The strength of the balloon tube wall was obtained from the stress equation in the circumferential direction of a known thin circular tube: f = pd / 2t as shown below. Calculation was made assuming that there was no change in tube wall thickness due to expansion.
f is the circumferential strength of the tube wall
p is the applied internal pressure
d is the diameter
t is the tube wall thickness
[0075]
[Table 18]
As is clear from Table 18, the breaking pressure and film strength of the balloon A both exceeded the comparative balloons B and C. The destruction of the comparative balloon B often started near the boundary between the cylindrical portion and the conical portion.
[0077]
【The invention's effect】
The catheter balloon of the present invention is a catheter balloon having a cylindrical portion and a cylindrical portion having conical portions that are inclined toward the outside toward the outside at both ends thereof, and the thickness of both or one cylindrical portion and the conical portion is The ratio is relatively smaller than that of the tube before the cylindrical portion is formed, and there is little stretching unevenness and alignment unevenness from both or one cylindrical portion to the conical portion. In particular, the portion that is difficult to be stretched in the vicinity of the conical portion of the cylindrical portion is accurately stretched to eliminate orientation unevenness, so that the strength as a molded product is improved and the balloon is thinned by the amount of the improved strength. Can be provided.
The balloon of the present invention is obtained by moving the tube in the axial direction in the opposite direction of the balloon during blow molding, and requires a conventional method, that is, an operation in which the tube is preliminarily processed in advance. It is possible to easily control the thickness of the balloon cylindrical portion and the conical portion as compared with a method that requires a complicated operation such as stacking the balloon cylindrical portions.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a balloon manufacturing apparatus of the present invention.
FIG. 2 is a diagram showing main refractive indexes in a circumferential direction (nx), an axial direction (ny), and a thickness direction (nz) of a balloon.
FIG. 3 is a diagram showing measurement sites such as a main refractive index of a balloon.
[Explanation of symbols]
1 tube
Type 2
3 Parisons
4 detection means
5, 6 Fixed part
7 Slide table
8 Pressure gas
Claims (19)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21958095A JP3766122B2 (en) | 1995-08-04 | 1995-08-04 | Catheter balloon and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21958095A JP3766122B2 (en) | 1995-08-04 | 1995-08-04 | Catheter balloon and manufacturing method thereof |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2005198438A Division JP2005305187A (en) | 2005-07-07 | 2005-07-07 | Catheter balloon and its manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0938195A JPH0938195A (en) | 1997-02-10 |
| JP3766122B2 true JP3766122B2 (en) | 2006-04-12 |
Family
ID=16737761
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21958095A Expired - Lifetime JP3766122B2 (en) | 1995-08-04 | 1995-08-04 | Catheter balloon and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3766122B2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2232250C (en) * | 1997-05-14 | 2007-06-26 | Navius Corporation | Balloon for a dilation catheter and method for manufacturing a balloon |
| JP2000217924A (en) * | 1999-02-01 | 2000-08-08 | Kanegafuchi Chem Ind Co Ltd | Extended body for extended catheter and its manufacture |
| JP2000279507A (en) * | 1999-03-30 | 2000-10-10 | Nippon Zeon Co Ltd | Balloon catheter with low-temperature blow-molded balloon |
| JP4922498B2 (en) * | 2001-05-11 | 2012-04-25 | 株式会社カネカ | Balloon parison |
| US20050187615A1 (en) * | 2004-02-23 | 2005-08-25 | Williams Michael S. | Polymeric endoprostheses with enhanced strength and flexibility and methods of manufacture |
| CA2847148C (en) * | 2011-09-29 | 2017-01-03 | Terumo Kabushiki Kaisha | Catheter balloon and balloon catheter |
| JPWO2022239356A1 (en) * | 2021-05-10 | 2022-11-17 |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4963313A (en) * | 1987-11-30 | 1990-10-16 | Boston Scientific Corporation | Balloon catheter |
| JP2555298B2 (en) * | 1990-11-10 | 1996-11-20 | テルモ株式会社 | CATHETER BALLOON, CATHETER BALLOON MANUFACTURING METHOD, AND BALLOON CATHETER |
-
1995
- 1995-08-04 JP JP21958095A patent/JP3766122B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0938195A (en) | 1997-02-10 |
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