JP5038824B2 - Biaxially stretched laminated film for reflectors - Google Patents
Biaxially stretched laminated film for reflectors Download PDFInfo
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Description
本発明は、反射板用二軸延伸積層フィルムに関する。 The present invention relates to a biaxially stretched laminated film for a reflector.
液晶ディスプレイは、テレビ、パソコン携帯電話などのディスプレイに幅広く用いられているが、液晶自体は自発光しないため、裏側にバックライトと呼ばれる発光装置を設置しなければならない。バックライトには単に光を照射する機能の他に、画面全体を均一に明るくすることも求められ、エッジ型または直下型と呼ばれる構造をとることが一般的である。エッジ型、直下型どちらの場合でも、最下部には反射板が設けられており、これにより光のロスを少なくし、画面全体をより明るくする機能を付与している。この反射板には光の高い反射性および高い拡散性が要求される。 Liquid crystal displays are widely used in displays such as televisions and personal computers and mobile phones. However, since the liquid crystal itself does not emit light, a light emitting device called a backlight must be installed on the back side. In addition to the function of simply irradiating light, the backlight is also required to uniformly brighten the entire screen, and generally has a structure called an edge type or a direct type. In both the edge type and the direct type, a reflecting plate is provided at the lowermost part, thereby providing a function of reducing light loss and making the entire screen brighter. This reflector is required to have high light reflectivity and high diffusibility.
無機粒子等ポリエステルと非相溶の物質を含有させ、延伸によってポリエステルとの界面でボイドを形成したポリエステルフィルムは、反射率が高く反射板用フィルムとして適している。しかし、ボイドを多く含むフィルムは、単層であると強度が不足する傾向にあり、破断しやすく生産性に劣る。
ボイドを多く含むフィルムでありながら十分な強度を得るためには、反射層を支持するための支持層を設けた積層フィルムとすればよい。積層フィルムは延伸後、ロール状に巻き取り、保管および輸送されるが、反射板用フィルムが反射層と支持層の2層から構成される場合、ロール状の巻き癖が残る。巻き癖が残っていると、積層フィルムを裁断し、所定の形状に折り曲げる等の加工工程でのハンドリング性が劣り、反射板を組み込んだバックライトユニットの生産性が劣ることになる。 In order to obtain sufficient strength while being a film containing a lot of voids, a laminated film provided with a support layer for supporting the reflective layer may be used. The laminated film is rolled up, stored and transported after being stretched, but when the reflector film is composed of two layers, a reflective layer and a support layer, a roll-shaped curl remains. If the curl remains, the handling property in a processing step such as cutting the laminated film and bending it into a predetermined shape is inferior, and the productivity of the backlight unit incorporating the reflector is inferior.
本発明は、十分な反射性能を備え、安定して製膜することができ、巻き癖が付き難い、液晶表示装置の反射板として好適に用いることのできる、反射板用二軸延伸積層フィルムを提供することを課題とする。 The present invention provides a biaxially stretched laminated film for a reflector that has sufficient reflection performance, can be stably formed, is less likely to be curled, and can be suitably used as a reflector for a liquid crystal display device. The issue is to provide.
すなわち本発明は、ポリエステル84〜70重量%および該ポリエステルと非相溶な樹脂16〜30重量%からなる反射層と、この層と接するポリエステルからなる支持層との2層から構成され、反射層は微細なボイドを有し積層フィルム全体厚みの80〜95%の厚みを占め、
反射層のポリエステルと支持層のポリエステルがいずれもイソフタル酸成分を共重合成分として5〜15モル%含む共重合ポリエチレンテレフタレートであることを特徴とする、反射板用二軸延伸積層フィルムである。
That is, the present invention is composed of two layers , a reflective layer composed of 84 to 70% by weight of polyester and 16 to 30% by weight of a resin incompatible with the polyester, and a support layer composed of polyester in contact with this layer. accounted for 80-95% of the thickness of the laminated film total thickness has fine voids,
Any polyester of the polyester and the support layer of the reflective layer has a copolymerized polyethylene terephthalate der Rukoto containing 5 to 15 mol% of isophthalic acid component as a copolymer component, a biaxially oriented laminated film for reflecting plate.
本発明によれば、十分な反射性能を備え、安定して製膜することができ、巻き癖が付き難い、液晶表示装置の反射板として好適に用いることのできる、反射板用二軸延伸積層フィルムを提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, it has sufficient reflective performance, can form into a stable film, it is hard to have a curl, and can be used suitably as a reflecting plate of a liquid crystal display device, Biaxial stretching lamination | stacking for reflecting plates A film can be provided.
以下、本発明を詳細に説明する。
本発明の反射板用二軸延伸積層フィルムは、反射層として機能するポリエステル84〜70重量%および該ポリエステルと非相溶な樹脂16〜30重量%からなる反射層と、この反射層を支持するポリエステルからなる支持層とからなる。
Hereinafter, the present invention will be described in detail.
The biaxially stretched laminated film for a reflector of the present invention supports a reflective layer comprising 84 to 70% by weight of polyester functioning as a reflective layer and 16 to 30% by weight of a resin incompatible with the polyester, and the reflective layer. It consists of a support layer made of polyester.
反射層は、「ポリエステルと非相溶な樹脂」を16〜30重量%含有する。非相溶な樹脂の含有量が16重量%未満であると巻き癖がつきやすく、30重量%を超えると安定製膜が困難である。反射層における、「ポリエステルと非相溶な樹脂」の含有量は、好ましくは21〜30重量%であり、この範囲であるとさらに巻き癖が付き難く好ましい。 The reflective layer contains 16 to 30% by weight of “polyester-incompatible resin”. If the content of the incompatible resin is less than 16% by weight, curling tends to occur, and if it exceeds 30% by weight, stable film formation is difficult. The content of the “polyester-incompatible resin” in the reflective layer is preferably 21 to 30% by weight.
[反射層]
反射層はポリエステルと、該ポリエステルと非相溶な樹脂から構成される。反射層は、積層フィルム全体厚みの60〜95%の厚みを占める。反射層が積層フィルム全体厚みの60%未満であると反射率が不足し高い輝度が得られず、95%を超えると製膜が不安定となり生産性が劣る。
[Reflective layer]
The reflective layer is made of polyester and a resin incompatible with the polyester. The reflective layer occupies 60 to 95% of the total thickness of the laminated film. When the reflective layer is less than 60% of the total thickness of the laminated film, the reflectance is insufficient and high luminance cannot be obtained, and when it exceeds 95%, film formation becomes unstable and productivity is inferior.
[ポリエステル]
ポリエステルとしては、熱可塑性の芳香族ポリエステルを用いる。このポリエステルとして、例えば、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレンジカルボキシレートを用いることができる。
[polyester]
As the polyester, a thermoplastic aromatic polyester is used. As this polyester, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalene dicarboxylate can be used.
機械的特性からポリエチレンテレフタレートが好ましい。
ポリエチレンテレフタレートは、好ましくは共重合ポリエチレンテレフタレートであり、イソフタル酸、ナフタレンジカルボン酸といったジカルボン酸成分を共重合成分として含む共重合ポリエチレンテレフタレートが好ましい。
Polyethylene terephthalate is preferred because of its mechanical properties.
The polyethylene terephthalate is preferably a copolymerized polyethylene terephthalate, and a copolymerized polyethylene terephthalate containing a dicarboxylic acid component such as isophthalic acid or naphthalenedicarboxylic acid as a copolymerization component is preferable.
共重合成分のジカルボン酸の共重合割合は、好ましくは1〜20モル%、さらに好ましくは3〜18モル%、特に好ましくは5〜15モル%である。共重合割合がこの範囲にないと、フィルムの製膜中にフィルムが破れ易く製膜性に劣ったり、熱安定性に欠けたフィルムになる場合があり好ましくない。 The copolymerization ratio of the dicarboxylic acid as a copolymerization component is preferably 1 to 20 mol%, more preferably 3 to 18 mol%, and particularly preferably 5 to 15 mol%. If the copolymerization ratio is not within this range, the film is easily broken during film formation, and the film-forming property may be inferior or the film may lack heat stability.
[非相溶な樹脂]
ポリエステルと非相溶な樹脂としては、例えばポリオレフィン、ポリスチレンを用いることができる。具体的には、例えばポリ−3−メチルブテン−1、ポリ−4−メチルペンテン−1、ポリエチレン、ポリプロピレン、ポリビニル−t−ブタン、1,4−トランス−ポリ−2,3−ジメチルブタジエン、ポリビニルシクロヘキサン、ポリスチレン、ポリフルオロスチレン、セルロースアセテートセルロースプロピオネート、ポリクロロトリフルオロエチレンを用いることができ、特に好ましくはポリプロピレン、ポリメチルペンテンを用いる。なかでも、ポリプロピレン、ポリメチルペンテンは樹脂自体が高い透明度を持つため、光の吸収が抑えられ、その結果、高い反射率を得ることができ、最適に用いられる。
[Incompatible resin]
As the resin incompatible with the polyester, for example, polyolefin and polystyrene can be used. Specifically, for example, poly-3-methylbutene-1, poly-4-methylpentene-1, polyethylene, polypropylene, polyvinyl t-butane, 1,4-trans-poly-2,3-dimethylbutadiene, polyvinylcyclohexane , Polystyrene, polyfluorostyrene, cellulose acetate cellulose propionate, and polychlorotrifluoroethylene, and particularly preferably polypropylene and polymethylpentene. Among these, since polypropylene and polymethylpentene have high transparency, the absorption of light is suppressed, and as a result, a high reflectance can be obtained and used optimally.
反射層において、ポリエステルと非相溶な樹脂は、積層フィルムを延伸する際に、ポリエステルとの界面で剥離することになる。その結果、反射層には微細なボイドが多数形成される。 In the reflective layer, the resin incompatible with the polyester is peeled off at the interface with the polyester when the laminated film is stretched. As a result, many fine voids are formed in the reflective layer.
ポリオレフィンとしてポリプロピレンを用いる場合、良好な分散性と混練性を得る観点から、メルトフローレート1〜30g/10分(JIS K7210:99での測定)のものが好ましい。 When polypropylene is used as the polyolefin, those having a melt flow rate of 1 to 30 g / 10 min (measured in JIS K7210: 99) are preferable from the viewpoint of obtaining good dispersibility and kneadability.
ポリオレフィンとしてポリメチルペンテンを用いる場合、良好な分散性と混練性を得る観点から、メルトフローレート10〜250g/10分(ASTM D1238での測定)のものが好ましい。 When polymethylpentene is used as the polyolefin, those having a melt flow rate of 10 to 250 g / 10 min (measured by ASTM D1238) are preferable from the viewpoint of obtaining good dispersibility and kneadability.
[分散剤]
上記のポリエステルおよび該ポリエステルと非相溶な樹脂の組成物には、非相溶樹脂の分散性を改善するために、ポリアルキレングリコールを添加することが好ましい。ポリアルキレングリコールとしては、例えばポリエチレングリコールを用いることができる。非相溶樹脂の良好な分散性を得るために、ポリアルキレングリコールの配合量は、ポリエステルおよび該ポリエステルと非相溶な樹脂の組成物100重量部に対して、例えば0.1〜5重量部、好ましくは0.5〜2重量部である。
[Dispersant]
In order to improve the dispersibility of the incompatible resin, it is preferable to add polyalkylene glycol to the polyester and the composition of the resin incompatible with the polyester. As the polyalkylene glycol, for example, polyethylene glycol can be used. In order to obtain good dispersibility of the incompatible resin, the blending amount of the polyalkylene glycol is, for example, 0.1 to 5 parts by weight with respect to 100 parts by weight of the composition of the polyester and the resin incompatible with the polyester. The amount is preferably 0.5 to 2 parts by weight.
[支持層]
支持層のポリエステルとしては、熱可塑性の芳香族ポリエステルを用いることができる。このポリエステルとしては、反射層で挙げたものと同じポリエステルおよび共重合ポリエステルを用いることができる。また、良好な製膜性を得る観点から、支持層で用いるポリエステルまたは共重合ポリエステルは、反射層で用いるポリエステルまたは共重合ポリエステルと同じものであることが好ましい。
[Support layer]
As the polyester for the support layer, a thermoplastic aromatic polyester can be used. As this polyester, the same polyesters and copolymerized polyesters as mentioned in the reflective layer can be used. Further, from the viewpoint of obtaining good film formability, the polyester or copolymer polyester used in the support layer is preferably the same as the polyester or copolymer polyester used in the reflective layer.
[添加剤]
本発明の積層フィルムの表面を滑らせ、ハンドリング性を良好にするために滑剤を配合してもよい。滑剤としては、有機物、無機物いずれを用いてもよく、無機物の滑剤としては、例えば酸化チタン、硫酸バリウム、炭酸カルシウム、二酸化珪素、アルミナの粒子を挙げることができる。これらの粒子は、板状、球状いずれの形状をとる粒子であってもよい。分散性と滑り性の観点から、これらの粒子は、好ましくは平均粒径0.1〜5.0μm、さらに好ましくは0.2〜4.0μmのものを用いる。滑剤は、本発明の積層フィルムの少なくとも一方の表面を形成する層に配合することが好ましい。
[Additive]
You may mix | blend a lubricant in order to slide the surface of the laminated | multilayer film of this invention, and to make handling property favorable. As the lubricant, either an organic substance or an inorganic substance may be used, and examples of the inorganic lubricant include titanium oxide, barium sulfate, calcium carbonate, silicon dioxide, and alumina particles. These particles may be either plate-like or spherical. From the viewpoint of dispersibility and slipperiness, these particles preferably have an average particle size of 0.1 to 5.0 μm, more preferably 0.2 to 4.0 μm. The lubricant is preferably blended in a layer that forms at least one surface of the laminated film of the present invention.
本発明の積層フィルムには、蛍光増白剤を配合してもよい。蛍光増白剤を反射層に配合する場合、反射層を構成するポリエステル組成物100重量部あたり、例えば0.005〜0.2重量部、好ましくは0.01〜0.1重量部配合する。0.005重量部未満であると350nm付近の波長域の反射率が十分でないので添加する意味が乏しく好ましくなく、他方、0.2重量部を越えると蛍光増白剤の持つ特有の色が現れてしまうため好ましくない。 You may mix | blend a fluorescent whitening agent with the laminated | multilayer film of this invention. When the fluorescent whitening agent is blended in the reflective layer, for example, 0.005 to 0.2 parts by weight, preferably 0.01 to 0.1 parts by weight is blended per 100 parts by weight of the polyester composition constituting the reflective layer. If the amount is less than 0.005 parts by weight, the reflectance in the wavelength region near 350 nm is not sufficient, so the meaning of adding is not preferable. On the other hand, if the amount exceeds 0.2 parts by weight, the unique color of the fluorescent whitening agent appears. This is not preferable.
蛍光増白剤としては、例えばOB−1(イーストマン社製)、Uvitex−MD(チバガイギー社製)、JP−Conc(日本化学工業所製)を用いることができる。 As the fluorescent brightening agent, for example, OB-1 (manufactured by Eastman), Uvitex-MD (manufactured by Ciba Geigy), or JP-Conc (manufactured by Nippon Chemical Industry Co., Ltd.) can be used.
本発明の積層フィルムには、必要に応じてさらに性能を上げるために、酸化防止剤、紫外線吸収剤を添加してもよい。また、これらの剤を含む塗剤を積層フィルムに塗布してもよい。 To the laminated film of the present invention, an antioxidant and an ultraviolet absorber may be added as necessary to further improve the performance. Moreover, you may apply | coat the coating agent containing these agents to a laminated | multilayer film.
[製造方法]
以下、本発明の反射板用二軸延伸積層フィルムを製造する方法を説明する。なお、延伸は、逐次二軸延伸法でもよく、同時二軸延伸法でもよいが、ここでは逐次二軸延伸法による製造方法を説明する。
[Production method]
Hereinafter, a method for producing the biaxially stretched laminated film for a reflector of the present invention will be described. The stretching may be a sequential biaxial stretching method or a simultaneous biaxial stretching method. Here, a production method by the sequential biaxial stretching method will be described.
まず、ダイから溶融したポリエステルをフィードブロックを用いた同時多層押出し法により、未延伸積層シートを製造する。すなわち、反射層(A層)を構成するポリエステルと非相溶樹脂の溶融物と、支持層(B層)を構成するポリエステルの溶融物とを、フィードブロックを用いてA層/B層となるように積層し、ダイに展開して、キャスティングドラム上に押出す。この時、フィードブロックで積層されたA層とB層のポリマーは、積層された形態を維持している。 First, an unstretched laminated sheet is produced by simultaneous multilayer extrusion using a feed block of polyester melted from a die. That is, the polyester and incompatible resin melt constituting the reflective layer (A layer) and the polyester melt constituting the support layer (B layer) are formed into an A layer / B layer using a feed block. And then rolled onto a die and extruded onto a casting drum. At this time, the polymers of the A layer and the B layer laminated by the feed block maintain the laminated form.
溶融工程においては、フィルターとして線径15μm以下のステンレス鋼細線よりなる平均目開き10〜100μm、好ましくは平均目開き20〜50μmの不織布型フィルターを用い、溶融ポリマーを濾過することが好ましい。この濾過を行なうことにより、一般的には凝集して粗大凝集粒子となやすい粒子の凝集や外部からの異物を抑えて、粗大異物の少ないフィルムを得ることができる。 In the melting step, it is preferable to filter the molten polymer using a non-woven filter having an average opening of 10 to 100 μm, preferably an average opening of 20 to 50 μm, made of a fine stainless steel wire having a wire diameter of 15 μm or less. By performing this filtration, it is possible to obtain a film with few coarse foreign matters by suppressing the aggregation of particles that are generally likely to aggregate into coarse aggregate particles and foreign foreign matters.
ダイより押出された未延伸積層シートは、キャスティングドラム上で冷却固化され、未延伸積層フィルムとなる。この未延伸積層フィルムをロール加熱、赤外線加熱といった手段で加熱し、縦方向に延伸して縦延伸積層フィルムを得る。この延伸は2個以上のロールの周速差を利用して行うのが好ましい。延伸温度は共重合ポリエステルのガラス転移点(Tg)以上の温度、さらにはTg〜(Tg+70)℃の温度とするのが好ましい。延伸倍率は、縦方向については好ましくは2.2〜4.0倍、さらに好ましくは2.3〜3.9倍である。2.2倍未満とするとフィルムの厚み斑が悪くなり良好なフィルムが得られず好ましくなく、4.0倍を超えると製膜中に破断が発生し易くなり好ましくない。 The unstretched laminated sheet extruded from the die is cooled and solidified on a casting drum to form an unstretched laminated film. This unstretched laminated film is heated by means such as roll heating or infrared heating, and stretched in the longitudinal direction to obtain a longitudinally stretched laminated film. This stretching is preferably performed by utilizing the difference in peripheral speed between two or more rolls. The stretching temperature is preferably a temperature equal to or higher than the glass transition point (Tg) of the copolyester, and more preferably a temperature of Tg to (Tg + 70) ° C. The draw ratio is preferably 2.2 to 4.0 times, more preferably 2.3 to 3.9 times in the longitudinal direction. When the ratio is less than 2.2 times, the thickness unevenness of the film is deteriorated and a good film cannot be obtained. When the ratio exceeds 4.0 times, breakage is likely to occur during film formation.
縦延伸後の積層フィルムは、続いて、横延伸、熱固定、熱弛緩の処理を順次施して二軸延伸された積層フィルムとするが、これら処理は積層フィルムを走行させながら行う。横延伸の処理は共重合ポリエステルのガラス転移点(Tg)より高い温度から始める。そして一般的には(Tg+5)〜(Tg+70)℃の温度まで昇温しながら行う。横延伸過程での昇温は連続的でも段階的(逐次的)でもよいが通常逐次的に昇温する。例えばテンターの横延伸ゾーンをフィルム走行方向に沿って複数に分け、ゾーン毎に所定温度の加熱媒体を流すことで昇温する。横延伸の倍率は、好ましくは2.5〜4.5倍、さらに好ましくは2.8〜3.9倍である。2.5倍未満であると積層フィルムの厚み斑が悪くなり、良好な積層フィルムを得ることができず好ましくなく、他方、4.5倍を超えると製膜中に破断が発生し易くなり好ましくない。 The laminated film after the longitudinal stretching is subsequently subjected to the treatment of transverse stretching, heat setting, and thermal relaxation to form a biaxially stretched laminated film, and these treatments are performed while the laminated film is running. The transverse stretching process starts from a temperature higher than the glass transition point (Tg) of the copolyester. In general, the temperature is raised to a temperature of (Tg + 5) to (Tg + 70) ° C. Although the temperature rise in the transverse stretching process may be continuous or stepwise (sequential), the temperature is usually raised sequentially. For example, the transverse stretching zone of the tenter is divided into a plurality along the film running direction, and the temperature is raised by flowing a heating medium having a predetermined temperature for each zone. The magnification of the transverse stretching is preferably 2.5 to 4.5 times, more preferably 2.8 to 3.9 times. If the thickness is less than 2.5 times, the thickness unevenness of the laminated film is deteriorated, and a favorable laminated film cannot be obtained. On the other hand, if it exceeds 4.5 times, breakage is likely to occur during film formation. Absent.
横延伸後の積層フィルムは両端を把持したまま、支持層のポリエステルの(Tm−20)〜(Tm−100)℃で定幅または10%以下の幅減少下で熱処理して熱収縮率を低下させるのがよい。熱処理がこれより高い温度であるとフィルムの平面性が悪くなり、厚み斑が大きくなり好ましくない。また、熱処理温度がこれより低いと熱収縮率が大きくなることがあり好ましくない。熱固定後フィルム温度を常温に戻す過程で(Tm−20)〜(Tm−100)℃の領域での熱収縮量を調整するために、把持している積層フィルムの両端を切り落し、積層フィルムの縦方向の引き取り速度を調整し、縦方向に弛緩させることができる。弛緩させる手段としてはテンター出側のロール群の速度を調整する。弛緩させる割合として、テンターのフィルムライン速度に対してロール群の速度ダウンを行い、好ましくは0.1〜1.5%、さらに好ましくは0.2〜1.2%、特に好ましくは0.3〜1.0%の速度ダウンを実施してフィルムを弛緩(この値を「弛緩率」という)して、弛緩率をコントロールすることによって縦方向の熱収縮率を調整する。また、フィルム横方向は両端を切り落すまでの過程で幅減少させて、所望の熱収縮率を得ることもできる。 The laminated film after transverse stretching is heat-treated at a constant width or a width reduction of 10% or less from (Tm-20) to (Tm-100) ° C. of the polyester of the support layer while holding both ends, thereby reducing the heat shrinkage rate. It is good to let them. When the heat treatment is performed at a temperature higher than this, the flatness of the film is deteriorated, and the thickness unevenness is increased, which is not preferable. On the other hand, if the heat treatment temperature is lower than this, the heat shrinkage rate may increase, which is not preferable. In order to adjust the heat shrinkage in the region of (Tm-20) to (Tm-100) ° C. in the process of returning the film temperature to room temperature after heat setting, both ends of the laminated film being gripped are cut off, The take-up speed in the vertical direction can be adjusted and relaxed in the vertical direction. As a means for relaxing, the speed of the roll group on the tenter exit side is adjusted. As the rate of relaxation, the speed of the roll group is reduced with respect to the film line speed of the tenter, preferably 0.1 to 1.5%, more preferably 0.2 to 1.2%, particularly preferably 0.3. The film is relaxed by performing a speed reduction of ˜1.0% (this value is referred to as “relaxation rate”), and the longitudinal heat shrinkage rate is adjusted by controlling the relaxation rate. Further, the width of the film in the horizontal direction can be reduced in the process until both ends are cut off, so that a desired heat shrinkage rate can be obtained.
このようにして得られる本発明の二軸延伸積層フィルムは、85℃の熱収縮率が、直交する2方向ともに0.5%以下、さらに好ましくは0.4%以下、最も好ましくは0.3%以下とすることができる。 The biaxially stretched laminated film of the present invention thus obtained has a heat shrinkage rate of 85 ° C. of 0.5% or less, more preferably 0.4% or less, and most preferably 0.3% in two orthogonal directions. % Or less.
二軸延伸後の積層フィルムの厚みは、好ましくは25〜350μm、さらに好ましくは40〜320μm、特に好ましくは50〜300μmである。25μm未満であると反射率が低下して好ましくなく、他方、350μmを超えるとこれ以上厚くしても反射率の上昇が望めないことから好ましくない。 The thickness of the laminated film after biaxial stretching is preferably 25 to 350 μm, more preferably 40 to 320 μm, and particularly preferably 50 to 300 μm. If the thickness is less than 25 μm, the reflectance is lowered, which is not preferable. On the other hand, if the thickness exceeds 350 μm, the reflectance cannot be increased even if the thickness is further increased.
このようにして得られる本発明の二軸延伸積層フィルムは、その少なくとも一方の表面の反射率が波長400〜700nmの平均反射率でみて95%以上、さらに好ましくは96%以上、さらに好ましくは97%以上の反射率を備えることになる。95%未満であると十分な画面の輝度を得ることができないので好ましくない。 The biaxially stretched laminated film of the present invention thus obtained has a reflectivity of at least one surface of 95% or more, more preferably 96% or more, more preferably 97, in terms of an average reflectivity at a wavelength of 400 to 700 nm. % Reflectivity. If it is less than 95%, it is not preferable because sufficient screen brightness cannot be obtained.
以下、実施例により本発明を詳述する。なお、各特性値は以下の方法で測定した。
(1)フィルム総厚み
フィルムサンプルをエレクトリックマイクロメーター(アンリツ製 K−402B)にて、10点厚みを測定して平均値を求め、フィルム総厚みとした。
Hereinafter, the present invention will be described in detail by way of examples. Each characteristic value was measured by the following method.
(1) Total film thickness A film sample was measured with an electric micrometer (K-402B, manufactured by Anritsu Corporation), 10-point thickness was measured, and an average value was obtained to obtain a total film thickness.
(2)各層の厚み
サンプルを三角形に切り出し、包埋カプセルに固定後、エポキシ樹脂にて包埋した。そして、包埋されたサンプルをミクロトーム(ULTRACUT−S)で縦方向に平行な断面を50nm厚の薄膜切片にした後、透過型電子顕微鏡を用いて、加速電圧100kvにて観察撮影し、写真から各層の厚みを10点測定して平均を求め、各層の厚みとした。
(2) Thickness of each layer A sample was cut into a triangle, fixed in an embedded capsule, and then embedded in an epoxy resin. Then, after embedding the sample with a microtome (ULTRACUT-S) into a thin film section having a thickness of 50 nm in parallel with the microtome, the specimen was observed and photographed with a transmission electron microscope at an acceleration voltage of 100 kv. The thickness of each layer was measured at 10 points, and the average was obtained as the thickness of each layer.
(3)反射率
分光光度計(島津製作所製UV−3101PC)に積分球を取り付け、BaSO4白板を100%とした時の反射率を波長400〜700nmにわたって測定し、得られたチャートより2nm間隔で反射率を読み取った。フィルムの構成が一方の面が反射層(A層)、他方の面が支持層(B層)の場合、A層側から測定を行った。上記の範囲内で平均値を求めた。
(3) Reflectivity A spectrophotometer (UV-3101PC manufactured by Shimadzu Corporation) is attached with an integrating sphere, and the reflectance when the BaSO 4 white plate is 100% is measured over a wavelength range of 400 to 700 nm, and 2 nm intervals from the obtained chart. I read the reflectance. When the configuration of the film was a reflective layer (A layer) on one side and a support layer (B layer) on the other side, the measurement was performed from the A layer side. An average value was determined within the above range.
(4)延伸性
縦方向2.5〜3.4倍、横方向3.5〜3.7倍に延伸して製膜し、安定に製膜できるか観察した。下記基準で評価した。
○:1時間以上安定に製膜できる
×:1時間以内に切断が発生し、安定な製膜ができない
(4) Stretchability The film was stretched 2.5 to 3.4 times in the longitudinal direction and 3.5 to 3.7 times in the transverse direction to form a film, and it was observed whether it could be stably formed. Evaluation was made according to the following criteria.
○: Stable film formation over 1 hour ×: Cutting occurs within 1 hour and stable film formation is not possible
(5)巻き癖
フィルムを10mm幅×150mm長さの短冊状に切り出し、直径1インチの紙管に巻き付け、常温、相対湿度55%にて24時間保管した後解放し、上に凹になるように平板に置いた際に観察される浮き上りを測定して下記基準で評価した。なお、紙管への巻きつけは、反射層を内面側にして巻くもの3本、外面側にして巻くもの3本として、合計6サンプルについて測定し、浮き上りの大きい方から3サンプルの平均をとった。
×: 45mmを超える
△:30〜45mm
○:30mm未満
(5) Wraps Cut the film into a strip of 10mm width x 150mm length, wrap it around a paper tube with a diameter of 1 inch, store it at room temperature and relative humidity 55% for 24 hours, release it, and make it concave The lift observed when placed on a flat plate was measured and evaluated according to the following criteria. In addition, as for the winding around the paper tube, a total of 6 samples were measured as three items wound with the reflection layer on the inner surface side and three items wound on the outer surface side, and the average of the three samples from the one with the largest lift was measured. I took it.
×: Over 45 mm Δ: 30-45 mm
○: Less than 30 mm
(6)ポリエステル組成物の固有粘度
オルトクロロフェノール溶媒に加熱溶解させ25℃で測定した。
(6) Intrinsic viscosity of the polyester composition The polyester composition was heated and dissolved in an orthochlorophenol solvent and measured at 25 ° C.
(7)微粒子の平均粒子径
HORIBA製LA−750パーティクルサイズアナライザー(Particle Size Analyzer)を用いて測定した。50マスパーセントに相当する粒子径を読み取り、この値を平均粒子径とした。なお、各粒子の粒子断面が円形でない場合には、粒子の長径と短径との平均をその粒子の粒子径とした。
(7) Average particle diameter of fine particles The average particle diameter was measured using an LA-750 particle size analyzer (Particle Size Analyzer) manufactured by HORIBA. The particle diameter corresponding to 50 mass percent was read, and this value was taken as the average particle diameter. In addition, when the particle cross section of each particle was not circular, the average of the major axis and minor axis of the particle was taken as the particle diameter of the particle.
[参考例1〜5、実施例4〜8、10〜12、14]
テレフタル酸ジメチル132重量部、イソフタル酸ジメチル18重量部(ポリエステルの酸成分に対して12モル%)、エチレングリコール96重量部、ジエチレングリコール3.0重量部、酢酸マンガン0.05重量部、酢酸リチウム0.012重量部を撹拌機、精留塔及び留出コンデンサーを備えた反応器に仕込み、撹拌しながら150〜235℃に徐々に昇温しつつ、反応の結果生成するメタノールを系外に留出させながら、エステル交換反応を行った。その後、リン酸トリメチル0.03重量部を添加し、エステル交換反応を終了させた。その後反応生成物に二酸化ゲルマニウム0.04重量部を添加し、撹拌装置、窒素導入口、減圧口、蒸留装置を備えた反応容器に移し、ついで撹拌しながら290℃まで昇温し、30Pa以下の高真空で重縮合反応を行った。固有粘度0.70dl/gの共重合ポリエステル組成物を得た。
[ Reference Examples 1-5, Examples 4-8, 10-12, 14]
132 parts by weight of dimethyl terephthalate, 18 parts by weight of dimethyl isophthalate (12 mol% based on the acid component of the polyester), 96 parts by weight of ethylene glycol, 3.0 parts by weight of diethylene glycol, 0.05 part by weight of manganese acetate, 0 parts of lithium acetate .012 parts by weight are charged into a reactor equipped with a stirrer, a rectifying column, and a distillation condenser, and methanol generated as a result of the reaction is distilled out of the system while gradually raising the temperature to 150 to 235 ° C. while stirring. The ester exchange reaction was carried out. Thereafter, 0.03 part by weight of trimethyl phosphate was added to complete the transesterification reaction. Thereafter, 0.04 part by weight of germanium dioxide was added to the reaction product, transferred to a reaction vessel equipped with a stirrer, a nitrogen inlet, a vacuum port, and a distillation device, then heated to 290 ° C. with stirring, and 30 Pa or less. The polycondensation reaction was performed under high vacuum. A copolyester composition having an intrinsic viscosity of 0.70 dl / g was obtained.
この共重合ポリエステル組成物を用い表1に示す無機粒子、非相溶樹脂を添加、それぞれ285℃に加熱された2台の押出機に供給し、反射層ポリマー、支持層ポリマーがA/Bとなるような2層フィードブロック装置を使用して合流させ、その積層状態を保持したままダイスよりシート状に成形した。なお、非相溶樹脂を添加する層には、その分散剤として分子量4000のポリエチレングリコールを1重量%添加した。さらにこのシートを表面温度25℃の冷却ドラムで冷却固化した未延伸フィルムを90℃にて長手方向(縦方向)に3.0倍延伸し、25℃のロール群で冷却した。続いて、縦延伸したフィルムの両端をクリップで保持しながらテンターに導き120℃に加熱された雰囲気中で長手に垂直な方向(横方向)に3.7倍延伸した。その後テンター内で210℃に加熱された雰囲気中で熱固定を行い、横方向に2%の幅入れを行い、縦方向に1.0%弛緩、室温まで冷やして反射板用二軸延伸積層フィルムを得た。得られたフィルムの層厚構成、反射板基材としての物性は表1の通りであった。 Using this copolymerized polyester composition, inorganic particles and incompatible resin shown in Table 1 were added and supplied to two extruders each heated to 285 ° C., and the reflective layer polymer and the support layer polymer were A / B. The two-layer feed block device was used to join, and the sheet was formed into a sheet from a die while maintaining the laminated state. In addition, 1% by weight of polyethylene glycol having a molecular weight of 4000 was added as a dispersant to the layer to which the incompatible resin was added. Further, an unstretched film obtained by cooling and solidifying the sheet with a cooling drum having a surface temperature of 25 ° C. was stretched 3.0 times in the longitudinal direction (longitudinal direction) at 90 ° C. and cooled by a roll group at 25 ° C. Subsequently, while holding both ends of the longitudinally stretched film with clips, the film was led to a tenter and stretched 3.7 times in a direction perpendicular to the longitudinal direction (lateral direction) in an atmosphere heated to 120 ° C. Then, heat setting in an atmosphere heated to 210 ° C in a tenter, 2% width in the horizontal direction, 1.0% relaxation in the vertical direction, cooling to room temperature, biaxially stretched laminated film for reflector Got. Table 1 shows the layer thickness constitution of the obtained film and the physical properties as a reflector base material.
[比較例6〜11]
テレフタル酸ジメチル100重量部とエチレングリコール70重量部との混合物に、酢酸マンガン四水和物0.032重量部を撹拌機、精留塔及びメタノール留出コンデンサーを設けた反応器に仕込み、撹拌しながら140℃から240℃まで徐々に昇温しつつ、反応の結果生成するメタノールを系外に留出させながら、エステル交換反応を行った。その後、リン酸トリメチル0.02重量部を添加し、エステル交換反応を終了させた。その後反応生成物に三酸化二アンチモン0.037重量部を添加して、撹拌装置、窒素導入口、減圧口、蒸留装置を備えた反応容器に移し、ついで撹拌しながら300℃まで昇温し、30Pa以下の高真空で重縮合反応を行った。固有粘度0.65dl/gのポリエステル組成物を得た。
[ Comparative Examples 6 to 11 ]
A mixture of 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol was charged with 0.032 parts by weight of manganese acetate tetrahydrate in a reactor equipped with a stirrer, rectification column and methanol distillation condenser, and stirred. While the temperature was gradually raised from 140 ° C. to 240 ° C., the transesterification reaction was carried out while distilling out the methanol produced as a result of the reaction. Thereafter, 0.02 part by weight of trimethyl phosphate was added to complete the transesterification reaction. Thereafter, 0.037 parts by weight of antimony trioxide is added to the reaction product, transferred to a reaction vessel equipped with a stirrer, a nitrogen inlet, a vacuum port, and a distillation device, and then heated to 300 ° C. while stirring. The polycondensation reaction was performed at a high vacuum of 30 Pa or less. A polyester composition having an intrinsic viscosity of 0.65 dl / g was obtained.
このポリエステル組成物を用い表1に示す無機粒子、非相溶樹脂を添加、それぞれ285℃に加熱された2台の押出機に供給し、反射層ポリマー、支持層ポリマーがA/Bとなるような2層フィードブロック装置を使用して合流させ、その積層状態を保持したままダイスよりシート状に成形した。なお、非相溶樹脂を添加する層には、その分散剤として分子量4000のポリエチレングリコールを1重量%添加した。さらにこのシートを表面温度25℃の冷却ドラムで冷却固化した未延伸フィルムを95℃にて長手方向(縦方向)に3.0倍延伸し、25℃のロール群で冷却した。続いて、縦延伸したフィルムの両端をクリップで保持しながらテンターに導き130℃に加熱された雰囲気中で長手に垂直な方向(横方向)に3.7倍延伸した。その後テンター内で220℃に加熱された雰囲気中で熱固定を行い、横方向に2%の幅入れを行い、縦方向に1.0%弛緩、室温まで冷やして反射板用二軸延伸積層フィルムを得た。得られたフィルムの層厚構成、反射板基材としての物性は表1の通りであった。 Using this polyester composition, the inorganic particles and incompatible resin shown in Table 1 are added and supplied to two extruders each heated to 285 ° C. so that the reflection layer polymer and the support layer polymer become A / B. A two-layer feed block device was used to join together, and the laminated state was maintained to form a sheet from a die. In addition, 1% by weight of polyethylene glycol having a molecular weight of 4000 was added as a dispersant to the layer to which the incompatible resin was added. Further, an unstretched film obtained by cooling and solidifying this sheet with a cooling drum having a surface temperature of 25 ° C. was stretched 3.0 times in the longitudinal direction (longitudinal direction) at 95 ° C., and cooled with a roll group at 25 ° C. Subsequently, while holding both ends of the longitudinally stretched film with clips, the film was drawn to a tenter and stretched 3.7 times in a direction perpendicular to the longitudinal direction (lateral direction) in an atmosphere heated to 130 ° C. Then, heat setting in an atmosphere heated to 220 ° C. in a tenter, 2% width in the horizontal direction, 1.0% relaxation in the vertical direction, cooling to room temperature, biaxially stretched laminated film for reflector Got. Table 1 shows the layer thickness constitution of the obtained film and the physical properties as a reflector base material.
[比較例1〜5]
実施例1と同様にポリマーを重合し、無機粒子、非相溶樹脂の添加量、および層厚構成を表1に示す通りとする他は実施例1と同様にして反射板用二軸延伸積層フィルムを得た。
[Comparative Examples 1-5]
Biaxially stretched laminate for reflector as in Example 1, except that polymer is polymerized in the same manner as in Example 1 and the addition amount of inorganic particles and incompatible resin and the layer thickness are as shown in Table 1. A film was obtained.
本発明の反射板用二軸延伸積層フィルムは、液晶表示装置の反射板として好適に用いることができる。 The biaxially stretched laminated film for a reflector of the present invention can be suitably used as a reflector for a liquid crystal display device.
Claims (2)
反射層のポリエステルと支持層のポリエステルがいずれもイソフタル酸成分を共重合成分として5〜15モル%含む共重合ポリエチレンテレフタレートであることを特徴とする、反射板用二軸延伸積層フィルム。 It consists of two layers: a reflective layer consisting of 84 to 70% by weight of polyester and 16 to 30% by weight of a resin incompatible with the polyester, and a support layer made of polyester in contact with this layer. The reflective layer has fine voids. Occupied 80 to 95% of the total thickness of the laminated film ,
Polyester with any polyester support layer also characterized copolymerized polyethylene terephthalate der Rukoto containing 5 to 15 mol% of isophthalic acid component as a copolymer component, a biaxially stretched laminated film reflector for the reflection layer.
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