201229587 六、發明說明： 【發明所屬之技術領域】 本發明涉及在液晶顯示裝置(Liquid Crystal Display)中使用的導光板與 包含該導光板的背光單元組件。 【先前技術】 心著工業社會發展為高度的資訊化時代，作制於顯示及傳遞各種資 訊的介質，t子顯示裝置的重要性越發增加。特別是，液晶顯示裝置(LCD) 的情況下，是作為液晶與半導體技術複合之技術集中的裝置而具有薄、輕、 消耗功率低的優點’ S此-直對其結構及製造技術進行研究開發，並在各 種領域中使用。 這樣的液晶顯示(LCD)裝置，由於液晶自身不能發光，因此在裝置的背 面另外設置光源來構現顏色及畫面。 作為上述發光裝置，廣泛使用有背光單元(BLU)，隨著最近液晶顯示裝 置的厚度變薄的趨勢’代替以往的冷陰極螢光燈(CCFL，㈣Cath〇de F1腦scent Lamp)而使用發光二極體(LED, Llght細㈣Di〇de)的情況急劇 增加。另外’ LED(LightEm論gDiGde)具有不使脉銀、色斜現優秀的 優點。 在側面分佈有LED的邊_ BLU，比在背光單·赫分佈有哪 的直下型’在絲神及產品厚度上具有伽，其顧細日益擴大。 在邊緣型BLU巾使雜娜在側面產生的光源制前面的導光板。在 光源上產生的光從導絲的側面人射到導光板_部，而從前面射出。在 這種方式巾，由於穿過導光板的光的路錄長，從而光損失增加，因此為 了防止出現這種現象，而主要使崎射率高的聚甲基丙雜甲酯(pMMA， Pdymethyimethacry㈣系列的材料。但是，聚甲基丙稀酸甲醋在結構上對 水分脆弱’應用了聚甲基丙驗㈣的導光板具有在高溫、高㈣環境下 彎曲及尺寸的穩定性下降的問題。 201229587 【發明内容】 本發明的目的在於，提供一種導光板，其為了克服對水分脆弱的聚^ 基丙烯酸fg旨的結構性缺點’而導人内吸收率優秀的樹脂來提高彎曲穩定 性及尺寸穩定性。 作為本發_優選的第丨實施例提供—種導光板，該導光板具有：基 材層，以及底層，其設置在上述基材層的一面，水分吸收率比基材層低。 根據上述實施例的基材層可以由聚甲基丙烯酸甲酯樹脂來製造。 根據上述實施例的底層可以由從聚碳酸酯樹脂、聚苯乙烯樹脂、丙烯 酸樹脂、烯烴類樹脂、它們的共聚物及它們混合物中選擇的樹脂來製造。 根據上述實施例的底層可以包含01〜10重量％的玻璃纖維。 根據上述實施例的玻璃纖維可以具有在一個方向上很長的形狀，並具 有方向性。 根據上述實施例的底層的厚度可以是iyoogm。 根據上述實施例的導光板可以具有：結構層，其是在沒有形成有底層 的基材層的一面上排列有多個立體結構的層。 根據上述實施例的結構層可以由紫外線硬化性樹脂或熱硬化性樹脂來 製造。 ‘ 根據上述實施例的結構層的立體結構的高度可以是25〜3〇〇μιη。 根據上述實施例的結構層的立體結構的節距可以是100〜500μπι。 作為本發明的另一優選的第2實施例，提供一種背光單元組件，該背 光單元組件具有上述導光板。 根據本發明，將水分吸收率不同的樹脂及具有方向性的玻璃纖維導入 到導光板中’從而即使在高溫.高濕的環境下也能夠提高導光板整體的彎曲 及尺寸穩定性。特別是，在底層導入玻璃纖維而使入射到側面的光向前面 散亂，從而能夠防止亮度下降。 【實施方式】 以下對本發明進行詳細說明。 本發明涉及如下所述的導光板，該導光板包含：基材層；以及底層， 201229587 其設置在上述基材層的_面，水分吸收率比基材層低，特別是，該導光板 可以在底層包含玻璃纖維。 本發明的導光板的特徵在於，為了解決作為導光板材料的聚甲基丙烯 酸甲酯一般在高溫高濕的環境下彎曲穩定性及尺寸穩定性下降的缺點，將 内吸收率優秀的樹脂及玻璃纖維導入到導光板中。 基材層能夠由聚甲基丙烯酸曱酯樹脂製造，為了解決聚甲基丙烯酸甲 酯樹脂對咼溫尚濕環境脆弱的缺點，能夠在基材層的至少一面形成水分吸 收率比基材層低的底層。 底層能夠由從聚碳酸酯樹脂、聚苯乙稀樹脂、丙埽酸樹脂、稀烴類樹 脂、或它們的共聚物及混合物中選擇的樹脂來製造，上述烯烴類樹脂可以 是迴圈烯烴聚合物(COP)或迴圈烯烴共聚物(coc)。基材層的聚甲基丙烯酸 曱西曰的水分吸收率為0.03% ’在底層中使用的樹脂的水分吸收率可以小於 0.03%。 另外，底層的厚度可以是1〜300μιη，該厚度在背光單元中可以根據LED 燈的位置而改變。從LED燈中出來的光穿過基材層而形成光路徑，如果底 層的厚度小於Ιμηι，則底層的水分吸收功能下降，如果底層的厚度超過 300μπι ’則當光通過底層而穿過時，有可能會產生光損失。 另外’可以在底層中含有玻璃纖維，上述玻璃纖維使光從導光板的下 部向上部散射，起到能夠防止由熱或水分引起的導光板的彎曲和尺寸變形 現象的作用。 上述玻璃纖維的含量可以是0.1〜10%重量份，如果小於0.1%重量份， 則防止彎曲和尺寸變形現象的效果不是很好，如果超過10%重量份，則由 玻璃纖維引起的光的散射程度嚴重，從而減少從前面射出的光量，而帶來 降低亮度的結果。 另外，玻璃纖維具有在一個方向上很長的形狀，可以具有方向性。具 體地說’玻璃纖維可以是圓柱、多角柱形狀’在擠壓時玻璃纖維能夠向擠 壓方向排列，此時玻璃纖維能夠以對光源垂直的方式排列(第2圖）。 為了形成如上所述的底層，可以在先形成基材層之後，再塗佈形成上 述底層的樹脂來製造，也可以通過對基材層與在對基材層和後述的結構層 進行壓出成型時形成底層的樹脂一起進行共擠壓來製造。 201229587 玻璃纖維在與形絲層的_旨勝之後，通職壓而以晶片形狀製 造，之後能触紐層進行共醜，而能夠在基材層的—面與底層樹脂混 合來進行塗佈。 作為如上所述形成底層的樹脂，可以從甲基丙烯酸甲酯-苯乙烯共聚 物、聚碳酸醋樹脂、聚苯乙烯樹脂、丙烯酸樹脂、稀麵樹脂、它們的共 聚物及混合物中選擇^ 〃 結構層可以形成在基材層上沒有形成有底層的一面上，在結構層上排 列有多個立體結構。另外，結構層能夠由紫外線硬化性樹脂或熱硬化性樹 脂來製造。 在本發明的導光板中’在結構層上排列的立體結構的形狀，雖然優選 為以通過峰__直方向的巾心線絲轉稱的結構，但是並不限定於 此另外’立體結構可以是南度為25μπι〜3〇〇μιη、節距為·卿〜叫的 結構。在導光板巾’從側面出發的光以導光板肋㈣賴來穿過，並從 導光板的前面射出，但是與在下面具有燈的直下型相比，具有光的散射大、 不能從^面射“損失的光量相職多的雜。在光射㈣方向上存在的 圖案提高光的直進性而增加亮度，因此具有上述所規定的高度及節距的立 體結構具有基於圖案而增加直進性的優點。 如上所述的結構層可以是通過與基材層進行共擠壓而形t即、可以 通過使構成基材層及結構層__基體樹驗過花紋輥關時進行共擠 壓而形成。 具體地說’如第1圖所示’基材層10及結構層30，能夠以沒有層與層 2的區分的方式而由-種樹脂來簡單地製造。擠_溫度賴會根據基 體樹脂而不同’但是優選為在20(rc〜勤。cjl進行擠愿。此時，上述基體樹 脂主要能夠使用聚甲基丙烯酸甲酯樹脂。 在將如上所述製造的導光板應用在背光單元組件上時，能夠實現即使 在高溫高濕的環境下也結構性地穩定的背光單元組件。 1以二Ϊ據實施例進"步詳細說明本發明，但是本㈣的範圍並不限 疋於下述的實施例。 <實施例1> 作為基材層利用聚甲基丙稀酸㈣樹脂、作為底層·甲基丙稀酸甲 201229587 醋-苯乙烯共聚物來進行了共擠壓。將導光板製造為：使基材層的厚度為 3mm、使底層的厚度為ι〇〇μιηβ此時，對於甲基丙烯酸甲酯_苯乙烯共聚物， 使用了甲基丙烯酸甲酯的重量比例為75的共聚物。 <實施例2> 除了對於曱基丙烯酸甲醋-苯乙烯共聚物，使用曱基丙烯酸甲酯的重量 比例為60的共聚物以外，以與實施例1相同的方法來製造導光板。 <實施例3> 除了對於甲基丙烯酸甲酯-苯乙烯共聚物，使用甲基丙烯酸.甲酯的重量 比例為30的共聚物以外，以與實施例1相同的方法來製造導光板。 <實施例4> 除了使底層的厚度為200μιη以外，以與實施例1相同的方法來製造導 光板。 <實施例5> 除了使底層的厚度為300μιη以外，以與實施例1相同的方法來製造導 光板。 <實施例6> 作為基材層利用聚甲基丙烯酸甲酯樹脂、作為底層利用聚碳酸酯樹脂 來進行共擠壓而製造導光板。使基材層的厚度為3mm、使底層的厚度為 ΙΟΟμιη ° <實施例7> 除了作為底層利用聚苯乙烯樹脂以外，以與實施例6相同的方法來製 造導光板。 <實施例8>至<實施例14> 在根據記載於表2的玻璃纖維含量來形成底層時，除了對甲基丙烯酸 甲酿·苯乙烯共聚物和玻璃纖維進行共擠壓以外，以與實施例丨至實施例7 相同的方法來分別製造導光板。 <比較例1> 雖然是以與上述實施例1相同的方法來製造導光板，但是是以沒有層 與層之間的區分的方式，都利用聚甲基丙烯酸甲酯樹脂來製造。 <比較例2> 201229587 雖然以與上述實施例7相同的方法來製造導光板，但是是以沒有層與 層之間的區分的方式，都利用聚甲基丙烯酸甲酯樹脂來製造。 >、 以如下所述的方法，對在上述實施例及比較例中準備的導光板實施 物理量評價，其結果如表2所示。 (1) 水分吸收率 通過ASTMD570測試方法來測量實施例及比較例中的導光板。在烤箱 中，以5〇t乾燥24小時而測量重量之後，在23。(：的水分中浸潰一天。以 乾燥後的重量與浸潰在水分後的重量的比來來測量水分吸收率。 (2) 彎曲變形量的測量（彎曲發生程度） 將實施例及比較例中的導光板，在50〇c、80%RH、96hf下保管而測量 了彎曲發生程度。利用Solartron公司的位移測量儀來測量彎曲發生程度， 如表1所示，將彎曲發生程度分成5階段來區分。 【表1】 彎曲發生級別 彎曲發生量 0 〇以上0.5mm以下 1 0.5mm以上2.0mm以下 2 2.0mm以上4.0mm以下 3 4.0mm以上6.0mm以下 4 6.0mm以上 將實施例及比較例中的導光板安裝在42寸液晶顯示面板用背光單元 上’使用亮度計(TOPCON公司’ BM-7)來進行測量，在測量任意的17個地 點上的壳度之後，求出了平均值。亮度是在每次測量時變化，因此使比較 例1的亮度為100來比較了相對值。 【表2】 區分 玻璃纖維含量 (重量％) 水分吸收率 (%) 彎曲發生程度 亮度(cd/m2) 實施例1 0.28 3 100 實施例2 0.26 3 99 實施例3 2 98 實施例4 0.27 2 99 201229587 實施例5 實施作ΓΓ 實施#ji" 實施斤11 實施例 實施例13 實施例14 比較例1 比較例2 5 5 6 7 4 3 0.26 023 020 027 025 023 026 025 022 0Λ9 030 030201229587 VI. Description of the Invention: TECHNICAL FIELD The present invention relates to a light guide plate used in a liquid crystal display device and a backlight unit assembly including the same. [Prior Art] With the development of industrial society as a highly information-based era, the importance of t-sub-display devices is increasing as a medium for displaying and transmitting various information. In particular, in the case of a liquid crystal display device (LCD), it is a device that is a combination of liquid crystal and semiconductor technology, and has the advantages of being thin, light, and low in power consumption. S-this research and development of its structure and manufacturing technology And used in various fields. In such a liquid crystal display (LCD) device, since the liquid crystal itself cannot emit light, a light source is additionally provided on the back surface of the device to construct a color and a picture. As the light-emitting device, a backlight unit (BLU) is widely used, and the trend of thinning the thickness of the liquid crystal display device has recently been used to replace the conventional cold cathode fluorescent lamp (CCFL, (C) Cath〇de F1 brain scent lamp). The situation of the polar body (LED, Llght fine (4) Di〇de) has increased dramatically. In addition, LED (LightEm on gDiGde) has the advantage of not making the pulse silver and color appear excellent. The side _ BLU in which the LED is distributed on the side has a gamma in the thickness of the silk god and the product thickness than the direct type in the backlight single-hertz distribution, and the detail is increasing. The light guide plate on the front side of the light source produced by the edge type BLU towel on the side. Light generated on the light source is emitted from the side of the guide wire to the light guide plate portion, and is emitted from the front side. In this manner, since the path of the light passing through the light guide plate is long, the light loss is increased, and therefore, in order to prevent this phenomenon, the polymethylmethacrylate (pMMA, Pdymethyimethacry (4) which has a high saturation rate is mainly used. A series of materials. However, polymethyl methacrylate methyl vinegar is structurally weak to moisture. The light guide plate using polymethyl acrylate (4) has a problem of bending under high temperature and high (IV) environment and dimensional stability. SUMMARY OF THE INVENTION An object of the present invention is to provide a light guide plate which improves the bending stability and size by introducing a resin having excellent internal absorption rate in order to overcome the structural disadvantage of the weak acrylic polymer fg. Stability As a preferred embodiment of the present invention, there is provided a light guide plate having a base material layer and a bottom layer disposed on one surface of the base material layer to have a lower moisture absorption rate than the base material layer. The substrate layer according to the above embodiment may be made of a polymethyl methacrylate resin. The underlayer according to the above embodiment may be derived from polycarbonate resin, polystyrene resin, C The resin is selected from the group consisting of an olefin resin, an olefin resin, a copolymer thereof, and a mixture thereof. The primer layer according to the above embodiment may contain from 01 to 10% by weight of glass fibers. The glass fiber according to the above embodiment may have one The shape in the direction is very long and has directionality. The thickness of the underlayer according to the above embodiment may be iyoogm. The light guide plate according to the above embodiment may have a structural layer which is one side of the substrate layer on which the underlayer is not formed. A layer having a plurality of three-dimensional structures arranged thereon. The structural layer according to the above embodiment may be made of an ultraviolet curable resin or a thermosetting resin. The height of the three-dimensional structure of the structural layer according to the above embodiment may be 25 to 3 〇. The pitch of the three-dimensional structure of the structural layer according to the above embodiment may be 100 to 500 μm. As another preferred second embodiment of the present invention, there is provided a backlight unit assembly having the above-described light guide plate. According to the present invention, a resin having a different moisture absorption rate and a glass fiber having directionality are introduced into the guide In the board, it is possible to improve the bending and dimensional stability of the entire light guide plate even in a high-temperature and high-humidity environment. In particular, the glass fiber is introduced into the bottom layer to disperse the light incident on the side surface, thereby preventing the brightness. [Embodiment] The present invention will be described in detail below. The present invention relates to a light guide plate comprising: a base material layer; and a bottom layer, 201229587, which is disposed on the surface of the base material layer, and has a moisture absorption rate. It is lower than the substrate layer, and in particular, the light guide plate may contain glass fibers in the underlayer. The light guide plate of the present invention is characterized in that polymethyl methacrylate as a material of the light guide plate is generally bent in a high temperature and high humidity environment. A disadvantage of reduced stability and dimensional stability, the resin and glass fiber having excellent internal absorption rate are introduced into the light guide plate. The base material layer can be made of polymethyl methacrylate resin, in order to solve the problem of polymethyl methacrylate resin The disadvantage of being fragile in a warm environment is that a bottom layer having a lower moisture absorption rate than the substrate layer can be formed on at least one side of the substrate layer. The bottom layer can be produced from a resin selected from a polycarbonate resin, a polystyrene resin, a propionate resin, a dilute hydrocarbon resin, or a copolymer and a mixture thereof, and the above olefin resin can be a loop olefin polymer. (COP) or loop olefin copolymer (coc). The water absorption rate of the polymethacrylic acid lanthanum oxime of the base material layer is 0.03%. The water absorption rate of the resin used in the underlayer may be less than 0.03%. Further, the thickness of the underlayer may be 1 to 300 μm, which may vary depending on the position of the LED lamp in the backlight unit. The light coming out of the LED lamp passes through the substrate layer to form a light path. If the thickness of the underlayer is less than Ιμηι, the moisture absorption function of the underlayer is lowered. If the thickness of the underlayer exceeds 300 μm, then when light passes through the bottom layer, it is possible Will produce light loss. Further, glass fibers may be contained in the underlayer, and the glass fibers scatter light from the lower portion of the light guide plate to the upper portion of the light guide plate, thereby preventing the bending and dimensional deformation of the light guide plate caused by heat or moisture. The content of the above glass fiber may be 0.1 to 10% by weight, and if it is less than 0.1% by weight, the effect of preventing bending and dimensional deformation is not very good, and if it exceeds 10% by weight, scattering of light by glass fiber The degree is severe, thereby reducing the amount of light emitted from the front, resulting in a decrease in brightness. In addition, the glass fiber has a shape that is long in one direction and can have directionality. Specifically, the glass fiber may be in the shape of a cylinder or a polygonal column. The glass fibers can be aligned in the extrusion direction at the time of extrusion, and the glass fibers can be arranged perpendicular to the light source (Fig. 2). In order to form the underlayer as described above, it may be produced by first forming a base material layer and then coating the resin forming the underlayer, or by extruding the base material layer and the base material layer and a structural layer described later. When the resin forming the underlayer is co-extruded together, it is manufactured. 201229587 After the glass fiber is used in the shape of the wire, it is manufactured in the shape of a wafer by the pressure of the film, and then the touch layer can be ugly, and the substrate layer can be coated with the underlying resin. As the resin forming the underlayer as described above, it is possible to select a structure from a methyl methacrylate-styrene copolymer, a polycarbonate resin, a polystyrene resin, an acrylic resin, a resin, a copolymer thereof, and a mixture thereof. The layer may be formed on one side of the substrate layer where the underlayer is not formed, and a plurality of three-dimensional structures are arranged on the structural layer. Further, the structural layer can be produced from an ultraviolet curable resin or a thermosetting resin. In the light guide plate of the present invention, the shape of the three-dimensional structure arranged on the structural layer is preferably a structure in which the wire is twisted by the peak of the peak __, but is not limited thereto. It is a structure in which the degree is 25μπι~3〇〇μιη, and the pitch is qing~~. The light from the side of the light guide plate is traversed by the light guide plate rib (4) and is emitted from the front surface of the light guide plate, but has a large scattering of light compared to the direct type having a lamp underneath. Shooting "the amount of light lost is a lot of miscellaneous. The pattern existing in the direction of the light (four) increases the straightness of the light and increases the brightness, so the three-dimensional structure having the height and pitch specified above has a straightforwardness based on the pattern. Advantages: The structural layer as described above may be formed by co-extrusion with the substrate layer, that is, by co-extrusion when the constituent substrate layer and the structural layer __the base tree are inspected when the pattern roll is closed. Specifically, as shown in Fig. 1, the base material layer 10 and the structural layer 30 can be easily produced from a resin without a layer and a layer 2. The extrusion temperature is based on the matrix resin. The difference is 'but preferably squeezing at 20 (rc ~ di. cjl. At this time, the above-mentioned base resin can mainly use polymethyl methacrylate resin. The light guide plate manufactured as described above is applied to the backlight unit assembly. When able A backlight unit assembly that is structurally stable even in a high-temperature and high-humidity environment. 1 The present invention will be described in detail in accordance with the embodiments, but the scope of the present invention is not limited to the following embodiments. <Example 1> As a base material layer, co-extrusion was carried out using a polymethyl methic acid (tetra) resin as a bottom layer·methyl methacrylate 201229587 vinegar-styrene copolymer. The light guide plate was manufactured as follows: The thickness of the base material layer was 3 mm, and the thickness of the underlayer was ι〇〇μηη. In this case, a copolymer of methyl methacrylate having a weight ratio of 75 was used for the methyl methacrylate-styrene copolymer. (Example 2) A light guide plate was produced in the same manner as in Example 1 except that the copolymer of methyl methacrylate-styrene copolymer was used in a weight ratio of methyl methacrylate of 60. Example 3> A light guide plate was produced in the same manner as in Example 1 except that a copolymer having a weight ratio of methacrylic acid methyl ester of 30 was used for the methyl methacrylate-styrene copolymer. 4> In addition to making the bottom A light guide plate was produced in the same manner as in Example 1 except that the thickness of the layer was 200 μm. <Example 5> A light guide plate was produced in the same manner as in Example 1 except that the thickness of the underlayer was 300 μm. Example 6> A light guide plate was produced by using a polymethyl methacrylate resin as a base material layer and a polycarbonate resin as a base layer, and the thickness of the base material layer was 3 mm, and the thickness of the base layer was ΙΟΟμιη °. <Example 7> A light guide plate was produced in the same manner as in Example 6 except that the polystyrene resin was used as the underlayer. <Example 8> to <Example 14> The glass according to Table 2 was used. When the fiber content was used to form the underlayer, the light guide plate was separately produced in the same manner as in Example 7 except that the methacrylic styrene styrene copolymer and the glass fiber were co-extruded. <Comparative Example 1> Although the light guide plate was produced in the same manner as in the above-described Example 1, it was produced by using a polymethyl methacrylate resin so as not to distinguish between layers. <Comparative Example 2> 201229587 Although the light guide plate was produced in the same manner as in the above-described Example 7, it was produced by using a polymethyl methacrylate resin so as not to distinguish between the layers. > The physical quantity of the light guide plate prepared in the above examples and comparative examples was evaluated by the following method, and the results are shown in Table 2. (1) Water absorption rate The light guide plates in the examples and the comparative examples were measured by the ASTM D570 test method. After measuring the weight in an oven at 5 Torr for 24 hours, at 23. The moisture absorption rate was measured by the ratio of the weight after drying to the weight after immersion in water. (2) Measurement of the amount of bending deformation (degree of occurrence of bending) In the examples and comparative examples The light guide plate was stored at 50 ° C, 80% RH, and 96 hf to measure the degree of occurrence of bending. The degree of bending was measured by a displacement gauge of Solartron, and as shown in Table 1, the degree of occurrence of bending was divided into five stages. [Table 1] Bending occurrence level bending occurrence amount 0 〇 or more 0.5 mm or less 1 0.5 mm or more and 2.0 mm or less 2 2.0 mm or more and 4.0 mm or less 3 4.0 mm or more and 6.0 mm or less 4 6.0 mm or more in the examples and comparative examples The light guide plate was mounted on a backlight unit for a 42-inch liquid crystal display panel using a luminance meter (TOPCON's BM-7) for measurement. After measuring the shell degree at any of the 17 locations, the average value was obtained. It was changed at each measurement, so the relative value was compared by setting the brightness of Comparative Example 1 to 100. [Table 2] Distinguishing the glass fiber content (% by weight) Moisture absorption rate (%) The degree of occurrence of bending (cd/m2) real Example 1 0.28 3 100 Example 2 0.26 3 99 Example 3 2 98 Example 4 0.27 2 99 201229587 Example 5 Implementation ΓΓ Implementation #ji" Implementation 斤11 Example Example 13 Example 14 Comparative Example 1 Comparative Example 2 5 5 6 7 4 3 0.26 023 020 027 025 023 026 025 022 0Λ9 030 030
如上述表1所示，可知在底層利用了水分吸收率低的丙烯酸系列的并 聚物的實施例’其導光板整體的水分吸收率低，彎曲發生程度減少。另外 可以在亮度方面上也能夠獲得同等級別的效果。 但是，用聚甲基丙烯酸甲酯樹脂來製造導光板整體的比較例1的導光 板，表現出水分吸收率和彎曲發生程度相對地高。 另外，可以確認到通過添加的玻璃纖維而使導光板對彎曲更穩定。 其結果，可知在將水分吸收率低的樹脂導入到導光板中時，在高溫高 濕的環境下’導光板整體的彎曲及尺寸穩定性提高了。 【圖式簡單說明】 圖1是本發明一實施例之導光板的縱剖面圖；以及 圖2是示出本發明一實施例之導光板上的玻璃纖維及排列形狀的圖。 【主要元件符號說明】 10 基材層 20 底層 30 結構層 40 光源 50 玻璃纖維 9As shown in the above Table 1, it is understood that the embodiment of the acrylic acid-based copolymer having a low moisture absorption rate in the bottom layer has a low moisture absorption rate of the entire light guide plate and a reduced degree of occurrence of warpage. In addition, the same level of effect can be obtained in terms of brightness. However, the light guide plate of Comparative Example 1 in which the entire light guide plate was produced using a polymethyl methacrylate resin showed a relatively high moisture absorption rate and a degree of occurrence of warpage. In addition, it was confirmed that the light guide plate was more stably bent by the added glass fibers. As a result, it has been found that when a resin having a low moisture absorption rate is introduced into the light guide plate, the bending and dimensional stability of the entire light guide plate are improved in an environment of high temperature and high humidity. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a longitudinal sectional view of a light guide plate according to an embodiment of the present invention; and Fig. 2 is a view showing a glass fiber and an arrangement shape of a light guide plate according to an embodiment of the present invention. [Main component symbol description] 10 Substrate layer 20 Bottom layer 30 Structure layer 40 Light source 50 Glass fiber 9