JP4297565B2 - Anisotropic film and method for producing the same - Google Patents

Description

(式中、Ｘ ¹ 〜Ｘ ⁴ は、それぞれ独立に炭素数１〜３０のアルキル基から選ばれるが、これらのアルキル基中の窒素原子と結合していないメチレン基は、二価の炭化水素基又は酸素原子で置換されていてもよい。ただし、これらの構造の中で酸素原子が連続して２個以上結合した構造は含まれない。)
また本発明によれば、ＤＮＡを含む樹脂基体を、３０℃以上の温水又は水蒸気中において、ＤＮＡの二重螺旋鎖を維持した状態で一定方向に５倍以上延伸することを特徴とする上記異方性フィルムの製造方法が提供される。
【０００５】
【発明の実施の形態】
以下、本発明について詳細に説明する。
本発明の異方性フィルムは、ＤＮＡを含み、ＤＮＡの二重螺旋鎖が維持された、特定の屈折率異方性を有する一軸異方性フィルムである。即ち、一軸延伸された異方性フィルムである。
本発明の異方性フィルムに含まれるＤＮＡは、各種の生物等から得られ特に限定されないが、容易に大量のＤＮＡが得られる点から、例えば、鮭や鰊等の魚類の白子から得られるＤＮＡ等が好適である。
本発明の異方性フィルムにおいて、ＤＮＡの含有割合は、少なすぎる場合、たとえ高倍率延伸されたものであってもＤＮＡ由来の異方性がほとんど発揮されない恐れがあるので、また、一方含有割合が１００重量％に近い場合、製造時の高倍率延伸が困難になる恐れがあるので、ＤＮＡの含有割合は、好ましくは１０〜９０重量％、特に、２０〜８０重量％の範囲が望ましい。
【０００６】
本発明の異方性フィルムは、ＤＮＡの他に、各種樹脂、各種有機化合物等を含有していても良い。
好ましくは、製造時の高倍率延伸が容易であり、屈折率異方性を高くするために、下記式(１)で示されるアンモニウム化合物を含み、このアンモニウム化合物と、上記ＤＮＡとが塩を形成した、ポリイオン複合体を含むことが望ましい。更には、このポリイオン複合体を主たる成分とすることが好ましく、特にフィルム中に９０重量％以上含有されることが望ましい。
【０００７】
【化２】

式中、Ｘ¹〜Ｘ⁴は、それぞれ独立に炭素数１〜３０のアルキル基から選ばれるが、これらのアルキル基中の窒素原子と結合していないメチレン基は、二価の炭化水素基又は酸素原子で置換されていてもよい。ただし、これらの構造の中で酸素原子が連続して２個以上結合した構造は含まれない。
二価の炭化水素基としては、好ましくは炭素数３〜２０、特に好ましくは炭素数５〜１５のものが使用できる。具体的には、特に限定されないが、パラフェニレン基、１，４−シクロヘキシレン基等が挙げられる。アルキル基中の二価の炭化水素基の数は、１〜５個が好ましく、１〜３個が特に好ましい。
【０００８】
上記アンモニウム化合物の分子構造によっては、フィルム製造時の延伸の難易が微妙に異なる場合があるので、上記アンモニウム化合物を含有させる場合には、その種類を適宜選択して使用することが好ましい。好ましいアンモニウム化合物としては、式(１)におけるＸ¹〜Ｘ⁴のうち少なくとも１つの基が酸素原子を含むことが好ましく、式(１)におけるＸ¹〜Ｘ⁴のうち少なくとも１つの基が酸素原子を２個以上含むことがさらに好ましく、式(１)におけるＸ¹〜Ｘ⁴のうち少なくとも１つの基が酸素原子を３個以上、８個以下含むことが特に好ましい。また、Ｘ¹〜Ｘ⁴のうち少なくとも１つの基の炭素数が、４以上、３０以下が好ましく、８以上、３０以下がさらに好ましく、１２以上、３０以下が特に好ましい。
上記酸素原子を含むアンモニウム化合物の酸素原子周辺の分子構造は適宜選択できるが、一般には酸素原子の一方にメチル基、他方にメチレン基、若しくは両側にメチレン基が結合している構造が好ましく、酸素原子の両側にメチレン基が結合している構造がさらに好ましく、酸素原子の両側にエチレン基が結合している構造が特に好ましい。このような好ましいアンモニウム化合物としては、例えば、下記構造式(1)〜(7)で示される化合物等が挙げられる。
【０００９】
【化３】

【００１０】
本発明の異方性フィルムは、更に、ＤＮＡに吸着する化合物等を含んでいても良い。ＤＮＡに吸着する化合物とは、ＤＮＡの塩基対層間に挿入される性質、若しくはＤＮＡの主溝又は副溝に吸着する性質を有する化合物を意味する。例えば、ある種の抗生物質、抗腫瘍剤、ＤＮＡ標識用色素として知られる化合物、ある種の変異原性物質として知られる化合物等が挙げられる。具体的には、ブレオマイシン、アクチノマイシンＤ、エチジウムブロマイド、白金化合物等が挙げられる。
ＤＮＡに吸着する化合物が含有される場合の含有割合は、該化合物とＤＮＡそれぞれの種類、あるいは本発明の異方性フィルムの用途によって適宜変更できるが、一般に、ＤＮＡに吸着する化合物が多すぎると、ＤＮＡの二重螺旋構造が壊れて等方的なフィルムとなる恐れがある。従って、ＤＮＡに吸着する化合物を含有させる場合の割合は、フィルム中のＤＮＡの１塩基対当たり、好ましくは０．００００１〜０．７個、特に好ましくは０．０００１〜０．３個、更に好ましくは０．０００５〜０．１個の割合で吸着する量が望ましい。
このようなＤＮＡに吸着する化合物は、後述する製造方法において、延伸後のフィルムに吸収させても、延伸前のフィルムに吸収させても、また予めフィルム材料となる樹脂基体に混合しておいても良いが、化合物の種類や含有割合によって、製造時の高倍率延伸が困難になる場合は、延伸後にフィルムに吸収させて含有させることが好ましい。
【００１１】
本発明の異方性フィルムは、波長５００ｎｍにおけるフィルム面内の屈折率異方性が、０．００５以上である必要があり、好ましくは、０．００５〜０．７、特に好ましくは０．００８〜０．７である。このような屈折率異方性は、一般に高延伸による高配向によって高くすることができるが、上述した従来報告されているフィルムでは、このような高い屈折率異方性は得られていない。０．００５以上の屈折率異方性を得るためには、後述する製造方法において、樹脂基体を５倍以上一軸延伸する必要がある。
上記屈折率異方性は、異方性フィルムの膜面内においてＤＮＡ二重螺旋鎖の配向方向に平行にその電場が振動する直線偏光に対する屈折率(Ｂ１)と、異方性フィルムの膜面内において該配向方向に垂直にその電場が振動する直線偏光に対する屈折率(Ｂ２)に対して、次の式により求めたものである。
屈折率異方性＝｜Ｂ１−Ｂ２｜、(ここで、｜ ｜は、絶対値を表す。)
【００１２】
本発明の異方性フィルムの膜厚は、一般にピンホールがなく、均一なフィルムを形成するという観点からは厚い方が良く、高配向度とするためにはよく延伸して薄い方が有利である。好ましい膜厚は用いるフィルムの成分により異なるが、通常、０．０５〜５００μｍが好ましく、０．１〜３００μｍがさらに好ましく、１〜２００μｍが特に好ましい。
本発明の異方性フィルムは、例えば、液晶用の位相差フィルム、偏光ビームスプリッタ等に特に有用である。
【００１３】
本発明の異方性フィルムの製造方法は、ＤＮＡを含む樹脂基体を、特定温度以上の温水又は水蒸気中において、ＤＮＡの二重螺旋鎖を維持した状態で一定方向に特定倍率以上延伸する方法である。
【００１４】
ＤＮＡを含む樹脂基体は、上記本発明の異方性フィルムを形成する成分を、例えば、溶媒に溶解し、支持体上にキャストしてフィルムを形成する方法等により得ることができる。要するに、樹脂基体は、通常、膜状として形成し、延伸処理されていない状態のものを意味する。この際、ＤＮＡの二重螺旋鎖が保持された状態である必要がある。
【００１５】
本発明の製造方法において、上記樹脂基体を延伸する際の環境条件は、温水中または水蒸気中であることが必要である。延伸時の最適な温度は、フィルムの組成によって異なるが、ＤＮＡの二重螺旋鎖を保持して５倍以上の延伸を可能とするために３０℃以上が必要である。通常は、３０〜１５０℃が好ましく、３０〜１００℃がさらに好ましく、４０〜８０℃が特に好ましい。
上記温水又は水蒸気には、水以外に他の物質を少量含むことができる。このような物質としては、用いる樹脂基体と反応したり、樹脂基体を分解したり、樹脂基体中のＤＮＡとキレートを形成し、延伸を難しくする作用がなく、水に少量溶解する又は水蒸気中に混合できることが可能なものであれば良い。例えば、アルコール等の水と相溶する溶媒；糖類等の水に溶解する有機化合物；塩化ナトリウム等の水に溶解する無機塩等が挙げられる。このような物質の最適な濃度は、用いる樹脂基体の組成、延伸温度、目的等によって適宜選択することができる。
【００１６】
樹脂基体を延伸する際の延伸倍率は、一定方向に５倍以上とする必要があり、６倍以上が好ましく、７倍以上がさらに好ましく、７．５倍以上が特に好ましい。なお、樹脂基体を例えば５倍に延伸するとは、樹脂基体を一定方向に延伸した際に、樹脂基体の延伸方向の長さが５倍になることを意味する。
延伸後に得られたフィルムを乾燥して使用する場合、乾燥時に収縮が起こる場合がある。このような収縮を抑制するには、フィルムを伸ばしたままで固定して乾燥させる方法が採用できる。
【００１７】
【実施例】
以下、本発明の実施例を示すが、本発明はこれらによって限定されるものではない。なお、本発明における屈折率異方性とは、上述した、屈折率異方性＝｜Ｂ１−Ｂ２｜により求めた値である。
【００１８】
実施例１
＜ＤＮＡ含有樹脂基体としてのキャストフィルムの作製＞
ジャーナル・オブ・アメリカン・ケミカル・ソサイエティ(Journal of American Chemical Society)、第１１８巻、４４号、１０６７９頁〜１０６７９頁(１９９６年)記載の材料、方法に従い作製した。
即ち、鮭の精子由来ＤＮＡ Ｎａ塩(シグマ社製)５０．０ｍｇを２０ｍｌの水に溶解した。氷冷撹拌下、Ｎ、Ｎ、Ｎ−トリメチル−Ｎ−(３、６、９、１２−テトラオキサドコシル)アンモニウムブロマイド１ｇを水２００ｍｌに溶解させた溶液を加え、白色繊維状のポリイオン複合体の沈澱を得た。濾過により沈澱１．４ｇを回収し、乾燥した。
得られたポリイオン複合体２５０ｍｇをクロロホルム／エタノール(４：１)１０ｇに溶解した。この溶液を樹脂プレート上に滴下し、溶媒飽和蒸気下に静置し室温でゆっくりと溶媒を蒸発させた。約２４時間後、樹脂プレートから剥がし、無色透明のキャストフィルムを得た。
【００１９】
＜異方性フィルムの作製＞
上記で得られたキャストフィルムを、４０℃の温水中において一定方向に延伸し、荷重をかけた状態で風乾し、延伸フィルムを作製した。乾燥後の延伸フィルムの長さを測定したところ、初期のキャストフィルムを８倍に延伸した長さを有していた。
更に、得られた延伸フィルムの屈折率異方性を、［鶴田、応用光学II、倍風館(１９９１)］５章１９２項に記載のセナルモン法により測定した。波長５００ｎｍにおけるレターデーションを測定し、触針式膜厚測定装置により測定した膜厚で除することにより屈折率異方性を求めた。その結果、屈折率異方性は０．００９であり、得られた延伸フィルムが異方性フィルムであることがわかった。また、得られた延伸フィルムをエチジウムブロマイドの水溶液に２４時間浸したところ、フィルムが赤色に変色し、エチジウムブロマイドが延伸フィルム内のＤＮＡに由来する二重螺旋鎖中の核酸塩基対にインターカレートしたことを確認した。
【００２０】
比較例１
実施例１と同様に得られたキャストフィルムを、２０℃の水中において一定方向に延伸し、荷重をかけた状態で風乾し、延伸フィルムを作製した。乾燥後の延伸フィルムの長さを測定したところ、初期のキャストフィルムを４倍に延伸した長さを有していた。
得られた延伸フィルムについて、実施例１と同様に屈折率異方性を測定した。その結果、屈折率異方性は０．００４であった。また、実施例１と同様にエチジウムブロマイドをインターカレートすることができた。
尚、得られた延伸フィルムを同一条件で更に延伸しようとしたところ、破断してしまった。
【００２１】
【発明の効果】
本発明の異方性フィルムは、高い屈折率異方性を有し、高度に配向したフィルムである。このフィルムを用いたフィルム光学素子は、極薄軽量であり、かつ性能が高いので、工業的利用価値が高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film having anisotropy useful in the field of optoelectronic technology or the like and a method for producing the same.
[0002]
[Prior art]
Highly anisotropic films have many uses in the fields of optical materials and electronic materials. In general, depending on the type of optical or electrical anisotropy required, the type of molecules to be aligned and the required degree of alignment are slightly different. However, high orientation generally tends to be preferred in any case. This is because optical or electrical anisotropy in the film, for example, refractive index anisotropy, dichroism, carrier mobility, and the like are significantly affected by the orientation of molecules constituting the film. Therefore, it is desirable to use a highly oriented film for each molecule that needs to be oriented depending on the type of anisotropy.
On the other hand, dioxyribonucleic acid (hereinafter abbreviated as DNA) has a so-called double helix structure, and each base pair is aligned substantially perpendicular to the molecular chain. Accordingly, if a film material can be prepared by arranging DNA molecular chains in one direction, each base pair is highly oriented in the film, and various optical or electrical anisotropies appear. It has already been reported by Okabata et al. That a film made of a polyion complex of DNA and a certain kind of ammonium compound can be produced, and that a film made of an oriented DNA molecular chain can be produced by stretching it [Journal of • American of the Chemical Society, 118, 44, 10679 (1996)].
However, in the stretching method in the above report, the limit of the stretching ratio in a state where the double helical strand of DNA is maintained is at most about 3.3 times, and a high-strength stretched film containing DNA and a method for producing the same are still known. Absent. Such a high-stretched film can be expected to have high anisotropy and can be widely used as an optical material.
[0003]
[Problems to be solved by the invention]
The objective of this invention is providing the anisotropic film with high refractive index anisotropy containing DNA, and its manufacturing method.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention can stretch at a high magnification by stretching a resin substrate containing DNA as a main component in a specific temperature range in the presence of water. In addition, the present inventors have found that high optical anisotropy is exhibited in that case, and have reached the present invention.
That is, according to the present invention, a uniaxial anisotropy film containing DNA and maintaining a double helix of DNA, the refractive index anisotropy in the film plane at a wavelength of 500 nm is 0.005 or more. Ah is, and the film is an anisotropic film characterized in that the polyion complex with ammonium compound having a structure represented by the DNA and the formula (1) as a main ingredient.
[Chemical formula 2]

(In the formula, X ^{1 to} X ⁴ are each independently selected from alkyl groups having 1 to 30 carbon atoms, and the methylene group not bonded to the nitrogen atom in these alkyl groups is a divalent hydrocarbon group. Alternatively, it may be substituted with an oxygen atom, provided that these structures do not include a structure in which two or more oxygen atoms are continuously bonded.)
Further, according to the present invention, the resin substrate containing DNA is stretched 5 times or more in a certain direction in warm water or steam at 30 ° C. or higher while maintaining a double helical chain of DNA. A method for producing an anisotropic film is provided.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The anisotropic film of the present invention is a uniaxial anisotropic film having a specific refractive index anisotropy containing DNA and maintaining a double helical strand of DNA. That is, it is a uniaxially stretched anisotropic film.
The DNA contained in the anisotropic film of the present invention is not particularly limited and can be obtained from various organisms, but from the point that a large amount of DNA can be easily obtained, for example, DNA obtained from fish larvae such as salmon and carp Etc. are suitable.
In the anisotropic film of the present invention, if the content ratio of DNA is too small, there is a possibility that the anisotropy derived from DNA is hardly exhibited even if it is stretched at a high magnification. When the ratio is close to 100% by weight, it may be difficult to stretch at a high magnification during production. Therefore, the DNA content is preferably 10 to 90% by weight, particularly 20 to 80% by weight.
[0006]
The anisotropic film of the present invention may contain various resins and various organic compounds in addition to DNA.
Preferably, it contains an ammonium compound represented by the following formula (1) in order to facilitate high-stretching during production and increase the refractive index anisotropy, and this ammonium compound and the DNA form a salt. It is desirable to include a polyion complex. Furthermore, it is preferable to use this polyion complex as a main component, and it is particularly desirable that the polyion complex is contained in the film in an amount of 90% by weight or more.
[0007]
[Chemical formula 2]

In the formula, X ^{1 to} X ⁴ are each independently selected from alkyl groups having 1 to 30 carbon atoms, and the methylene group not bonded to the nitrogen atom in these alkyl groups is a divalent hydrocarbon group or It may be substituted with an oxygen atom. However, a structure in which two or more oxygen atoms are continuously bonded is not included in these structures.
As the divalent hydrocarbon group, those having 3 to 20 carbon atoms, particularly preferably those having 5 to 15 carbon atoms can be used. Specific examples include, but are not limited to, a paraphenylene group and a 1,4-cyclohexylene group. The number of divalent hydrocarbon groups in the alkyl group is preferably 1 to 5, particularly preferably 1 to 3.
[0008]
Depending on the molecular structure of the ammonium compound, the difficulty of stretching during film production may be slightly different. Therefore, when the ammonium compound is contained, it is preferable to select and use the type appropriately. Preferred ammonium compound preferably contains at least one group is an oxygen atom of X ¹ to X ⁴ in the formula (1), at least one group is an oxygen atom of X ¹ to X ⁴ in the formula (1) Is more preferable, and it is particularly preferable that at least one group among X ^{1 to} X ⁴ in the formula (1) includes 3 or more and 8 or less oxygen atoms. The number of carbon atoms of at least one group of X ¹ to X ⁴ is 4 or more, preferably 30 or less, 8 or more, more preferably 30 or less, 12 or more, particularly preferably 30 or less.
The molecular structure around the oxygen atom of the ammonium compound containing the oxygen atom can be selected as appropriate, but in general, a structure in which a methyl group is bonded to one oxygen atom, a methylene group to the other, or a methylene group bonded to both sides is preferable. A structure in which methylene groups are bonded to both sides of the atom is more preferable, and a structure in which ethylene groups are bonded to both sides of the oxygen atom is particularly preferable. Examples of such preferred ammonium compounds include compounds represented by the following structural formulas (1) to (7).
[0009]
[Chemical 3]

[0010]
The anisotropic film of the present invention may further contain a compound that adsorbs to DNA. The compound that adsorbs to DNA means a compound that has the property of being inserted between DNA base pair layers, or the property of adsorbing in the main groove or sub groove of DNA. Examples include certain antibiotics, antitumor agents, compounds known as DNA labeling dyes, compounds known as certain mutagenic substances, and the like. Specific examples include bleomycin, actinomycin D, ethidium bromide, platinum compounds, and the like.
The content ratio when a compound that adsorbs to DNA is contained can be appropriately changed depending on the type of the compound and DNA, or the use of the anisotropic film of the present invention. There is a risk that the double helix structure of DNA is broken and an isotropic film is formed. Therefore, the ratio in the case of containing a compound that adsorbs to DNA is preferably 0.00001 to 0.7, particularly preferably 0.0001 to 0.3, more preferably, per 1 base pair of DNA in the film. The amount adsorbed at a rate of 0.0005 to 0.1 is desirable.
Such a compound that adsorbs to DNA may be absorbed in a film after stretching, absorbed in a film before stretching, or mixed in advance with a resin substrate as a film material in the production method described later. However, depending on the type and content ratio of the compound, when high-strength stretching during production becomes difficult, the film is preferably absorbed and contained after stretching.
[0011]
In the anisotropic film of the present invention, the in-plane refractive index anisotropy at a wavelength of 500 nm needs to be 0.005 or more, preferably 0.005 to 0.7, particularly preferably 0.008. ~ 0.7. Such refractive index anisotropy can generally be increased by high orientation by high stretching, but such a high refractive index anisotropy is not obtained in the above-described conventionally reported films. In order to obtain a refractive index anisotropy of 0.005 or more, it is necessary to uniaxially stretch the resin substrate 5 times or more in the production method described later.
The refractive index anisotropy includes the refractive index (B1) for linearly polarized light whose electric field vibrates in parallel with the orientation direction of the DNA double helix in the film surface of the anisotropic film, and the film surface of the anisotropic film. The refractive index (B2) for linearly polarized light whose electric field oscillates perpendicularly to the orientation direction is obtained by the following equation.
Refractive index anisotropy = | B1-B2 |, where || represents an absolute value.
[0012]
The film thickness of the anisotropic film of the present invention is generally thicker from the viewpoint of forming a uniform film without pinholes, and in order to obtain a high degree of orientation, it is advantageous to stretch and thin. is there. Although a preferable film thickness changes with the components of the film to be used, it is usually preferably 0.05 to 500 μm, more preferably 0.1 to 300 μm, and particularly preferably 1 to 200 μm.
The anisotropic film of the present invention is particularly useful for, for example, a retardation film for liquid crystal, a polarizing beam splitter, and the like.
[0013]
The method for producing an anisotropic film of the present invention is a method in which a resin substrate containing DNA is stretched in a certain direction at a specific magnification or more in warm water or water vapor at a specific temperature or higher while maintaining a double helical strand of DNA. is there.
[0014]
The resin substrate containing DNA can be obtained by, for example, a method of forming the film by dissolving the components forming the anisotropic film of the present invention in a solvent and casting the solution on a support. In short, the resin substrate usually means a film formed in a film shape and not stretched. At this time, it is necessary that the double helix strand of DNA is maintained.
[0015]
In the production method of the present invention, the environmental condition for stretching the resin substrate needs to be in warm water or steam. The optimum temperature at the time of stretching varies depending on the composition of the film, but 30 ° C. or higher is necessary in order to retain the double helical strand of DNA and enable stretching of 5 times or more. Usually, 30 to 150 ° C is preferable, 30 to 100 ° C is more preferable, and 40 to 80 ° C is particularly preferable.
The warm water or water vapor can contain a small amount of other substances besides water. Such substances do not react with the resin substrate used, decompose the resin substrate, form a chelate with the DNA in the resin substrate, make stretching difficult, dissolve in a small amount in water, or in water vapor Any material that can be mixed is acceptable. For example, a solvent that is compatible with water such as alcohol; an organic compound that dissolves in water such as sugar; an inorganic salt that dissolves in water such as sodium chloride; The optimum concentration of such a substance can be appropriately selected depending on the composition of the resin substrate used, the stretching temperature, the purpose, and the like.
[0016]
The draw ratio at the time of drawing the resin substrate needs to be 5 times or more in a fixed direction, preferably 6 times or more, more preferably 7 times or more, and particularly preferably 7.5 times or more. In addition, extending | stretching a resin base | substrate 5 times means that the length of the extending | stretching direction of a resin base | substrate will be 5 times when extending | stretching a resin base | substrate in a fixed direction.
When the film obtained after stretching is dried and used, shrinkage may occur during drying. In order to suppress such shrinkage, a method in which the film is fixed and dried while being stretched can be employed.
[0017]
【Example】
Examples of the present invention will be described below, but the present invention is not limited thereto. The refractive index anisotropy in the present invention is a value obtained by the above-described refractive index anisotropy = | B1-B2 |.
[0018]
Example 1
<Production of cast film as DNA-containing resin substrate>
It was prepared according to the materials and methods described in Journal of American Chemical Society, Vol. 118, No. 44, pages 10679-10679 (1996).
That is, 50.0 mg of DNA Na salt derived from salmon sperm (manufactured by Sigma) was dissolved in 20 ml of water. Under ice-cooling stirring, a solution of 1 g of N, N, N-trimethyl-N- (3,6,9,12-tetraoxadocosyl) ammonium bromide dissolved in 200 ml of water was added to form a white fibrous polyion complex. A precipitate was obtained. 1.4g of precipitate was collected by filtration and dried.
250 mg of the obtained polyion complex was dissolved in 10 g of chloroform / ethanol (4: 1). This solution was dropped on a resin plate, allowed to stand under solvent saturated vapor, and the solvent was slowly evaporated at room temperature. After about 24 hours, the film was peeled off from the resin plate to obtain a colorless and transparent cast film.
[0019]
<Production of anisotropic film>
The cast film obtained above was stretched in a certain direction in warm water at 40 ° C., and air-dried under a load, to prepare a stretched film. When the length of the stretched film after drying was measured, it had a length obtained by stretching the initial cast film by 8 times.
Furthermore, the refractive index anisotropy of the obtained stretched film was measured by the Senarmon method described in Chapter 5 192 of [Tsuruta, Applied Optics II, Shufukan (1991)]. Refractive index anisotropy was determined by measuring retardation at a wavelength of 500 nm and dividing by the film thickness measured by a stylus type film thickness measuring device. As a result, the refractive index anisotropy was 0.009, and it was found that the obtained stretched film was an anisotropic film. Moreover, when the obtained stretched film was immersed in an aqueous solution of ethidium bromide for 24 hours, the film turned red, and ethidium bromide was intercalated into nucleobase pairs in the double helix derived from DNA in the stretched film. I confirmed that.
[0020]
Comparative Example 1
The cast film obtained in the same manner as in Example 1 was stretched in a certain direction in water at 20 ° C., and air-dried under a load, to prepare a stretched film. When the length of the stretched film after drying was measured, it had a length obtained by stretching the initial cast film four times.
The obtained stretched film was measured for refractive index anisotropy in the same manner as in Example 1. As a result, the refractive index anisotropy was 0.004. Moreover, ethidium bromide could be intercalated as in Example 1.
When the obtained stretched film was further stretched under the same conditions, it was broken.
[0021]
【The invention's effect】
The anisotropic film of the present invention is a highly oriented film having high refractive index anisotropy. A film optical element using this film is extremely thin and light and has high performance, and therefore has high industrial utility value.

Claims (3)

Comprises deoxyribonucleic acid, a film of uniaxial anisotropy double helix strand of deoxyribonucleic acid is maintained state, and are the refractive index anisotropy of 0.005 or more film plane at a wavelength of 500 nm, and the film An anisotropic film comprising a polyion complex of dioxyribonucleic acid and an ammonium compound having a structure represented by formula (1) as a main component .

(In the formula, X ^{1 to} X ⁴ are each independently selected from alkyl groups having 1 to 30 carbon atoms, and the methylene group not bonded to the nitrogen atom in these alkyl groups is a divalent hydrocarbon group. Alternatively, it may be substituted with an oxygen atom, provided that these structures do not include a structure in which two or more oxygen atoms are continuously bonded.) The anisotropic film according to claim 1 , wherein the film contains a compound that adsorbs to dioxyribonucleic acid.   3. The resin substrate containing dioxyribonucleic acid is stretched 5 times or more in a certain direction in a hot water or water vapor at 30 ° C. or higher while maintaining a double helical chain of dioxyribonucleic acid. A method for producing an anisotropic film.