Summary of the invention
The present invention is directed to prior art light diffusion plate for straight-down-type backlight LCD above shortcomings, a kind of light diffusion plate for straight-down-type backlight LCD is provided, even warpage takes place under heating condition, can stipulate that also its bending direction is protruding in the back light direction, partly contacting between other assemblies with backlight of can preventing from simultaneously to cause owing to warpage produces scuffing, do not have the light diffusing sheet of brightness disproportionation.
The technical scheme that the present invention solves the problems of the technologies described above is as follows: a kind of light diffusion plate for straight-down-type backlight LCD comprises first laminate, second laminate and three ply board, and described second laminate is arranged between described first laminate and the three ply board; Described first laminate comprises the first kind resin of 100 mass parts, the light diffusing agent of 0.5 mass parts~5 mass parts and the ultraviolet light absorber of 0.01 mass parts~10 mass parts; Described second laminate comprises the first kind resin of 100 mass parts and the light diffusing agent of second resinoid and 0.5 mass parts~5 mass parts; Described three ply board comprises second resinoid of 100 mass parts, the light diffusing agent of 0.5 mass parts~5 mass parts and the ultraviolet light absorber of 0.01 mass parts~10 mass parts; The described second resinoid thermal expansivity is greater than the described first resinoid thermal expansivity.
The invention has the beneficial effects as follows: light diffusing sheet of the present invention is the multilayer board that is made by two kinds of different resins of thermal expansivity, wherein this multiple-plate skin is made of the low thermal coefficient of expansion resin, internal layer is made of the high thermal expansion coefficient resin, the middle layer is made of with the resin combination that certain proportion mixes these two kinds of resins, and with by skin to the internal layer direction, thermal expansivity forms by ascending mode is laminated.Because under the influence of the heat of light source etc.,, can stipulate that it protrudes to high thermal expansion coefficient layer direction, the light source direction that promptly supports or opposes protrusion when light diffusing sheet because the internal stress that the difference of each layer thermal expansivity produces makes when this kind light diffusing sheet produces warpage.Described light diffusing sheet demonstrates good light diffusing and light fastness simultaneously.
Described second laminate is a single layer structure, and first kind resin and the mixed thermal expansivity of second resinoid are greater than the described first resinoid thermal expansivity, and less than the described second resinoid thermal expansivity in described second laminate.
Further, described second laminate is to comprise two-layer at least sandwich construction, every layer in the described sandwich construction includes first kind resin, second resinoid and light diffusing agent, the first kind resin and the second resinoid weight ratio reduce on the direction of three ply board gradually along described first laminate in described each layer, and first kind resin and the mixed thermal expansivity of second resinoid increase on the direction of three ply board gradually along described first laminate in described each layer.
Further, the described first resinoid thermal expansivity is 5 * 10
-5M/m ℃~8 * 10
-5M/m ℃, the described second resinoid thermal expansivity is 10 * 10
-5M/m ℃~13 * 10
-5M/m ℃.
Further, described first kind resin comprises one or more in polystyrene, polychlorostyrene, poly-halogenated styrenes class, polyvinyl toluene and the polyoxyethylene alkylphenyl vinyl resins.
Further, described second resinoid comprises one or more in polymethylmethacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, polycyclohexyl methacrylate, polymethylacrylic acid octadecane ester, polymethacrylate, polymethyl acrylate, polyethyl acrylate, butyl polyacrylate, polyacrylic acid cyclohexyl, polyacrylic acid phenyl ester, polypropylene acid benzyl ester and the polyacrylate resinoid.
Further, described light diffusing agent exists with atomic form, comprises in type siloxane polymer particle, acrylic polymers particle, calcium carbonate particle, barium sulphate particle, Titanium particles, silicon oxide particle, talcum particle, white carbon particle, mica particle, glass particle, aluminum hydroxide particles, magnesia particle, zinc paste particle and the polystyrene resins particle one or more.
Further, described ultraviolet light absorber comprises that benzophenone series ultraviolet light absorber, triazine are that ultraviolet light absorber, benzotriazole are that ultraviolet light absorber and cyclic imide base ester are one or more in the ultraviolet light absorber.
Further, when described light diffusing sheet is installed on the direct down type backlight LCD, the front side of described light diffusing sheet be described first laminate towards the liquid crystal panel setting, the back side of described light diffusing sheet is that described three ply board is towards the back light setting.
Further, the thickness of described light diffusing sheet is 0.3 millimeter~4 millimeters.
Embodiment
Below in conjunction with accompanying drawing principle of the present invention and feature are described, institute gives an actual example and only is used to explain the present invention, is not to be used to limit scope of the present invention.
Fig. 1 is the structural representation of light diffusion plate for straight-down-type backlight LCD first embodiment of the present invention.As shown in Figure 1, described light diffusing sheet comprises first laminate 101, second laminate 102 and the three ply board 103, and described second laminate 102 is arranged between described first laminate 101 and the three ply board 103.Described first laminate 101 comprises the first kind resin of 100 mass parts, the light diffusing agent of 0.5 mass parts~5 mass parts and the ultraviolet light absorber of 0.01 mass parts~10 mass parts.Described second laminate 102 comprises the first kind resin of 100 mass parts and the light diffusing agent of second resinoid and 0.5 mass parts~5 mass parts.Described three ply board 103 comprises second resinoid of 100 mass parts, the light diffusing agent of 0.5 mass parts~5 mass parts and the ultraviolet light absorber of 0.01 mass parts~10 mass parts, and the described second resinoid thermal expansivity is greater than the described first resinoid thermal expansivity.The thickness of described light diffusing sheet is 0.3 millimeter~4 millimeters.
In described first laminate 101 with main body composition in its prescription promptly the first resinoid addition be benchmark (100 mass parts), other compositions are that light diffusing agent and ultraviolet light absorber are object of reference with the first resinoid content in the prescription, represent with its number percent that accounts for first kind resin quality, be respectively the light diffusing agent of 0.5 mass parts~5 mass parts and the ultraviolet light absorber of 0.01 mass parts~10 mass parts.
In described second laminate 102 with its prescription in the main body composition be that first kind resin and second resinoid total addition are benchmark (100 mass parts), other compositions are that light diffusing agent is an object of reference with the first kind resin and the second resinoid total content in the prescription, represent with its number percent that accounts for the first kind resin and the second resinoid gross mass, be respectively the light diffusing agent of 0.5 mass parts~5 mass parts.In described second laminate 102, the described first kind resin and second resinoid can mix by arbitrary proportion, as long as guarantee all to contain, preferably, the described first kind resin and the second resinoid mass ratio are 1: 4~4: 1.
In the described three ply board 103 with main body composition in its prescription promptly the second resinoid addition be benchmark (100 mass parts), other compositions are that light diffusing agent and ultraviolet light absorber are object of reference with the second resinoid content in the prescription, represent with its number percent that accounts for the second resinoid quality, be respectively the light diffusing agent of 0.5 mass parts~5 mass parts and the ultraviolet light absorber of 0.01 mass parts~10 mass parts.
The described first resinoid thermal expansivity is 5 * 10
-5M/m ℃~8 * 10
-5M/m ℃, described first kind resin comprises one or more in polystyrene, polychlorostyrene, poly-halogenated styrenes class, polyvinyl toluene and the polyoxyethylene alkylphenyl vinyl resins.
The described second resinoid thermal expansivity is 10 * 10-5m/m ℃~13 * 10-5m/m ℃, and described second resinoid comprises one or more in polymethylmethacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, polycyclohexyl methacrylate, polymethylacrylic acid octadecane ester, polymethacrylate, polymethyl acrylate, polyethyl acrylate, butyl polyacrylate, polyacrylic acid cyclohexyl, polyacrylic acid phenyl ester, polypropylene acid benzyl ester and the polyacrylate resinoid.
Thermal expansivity in the present embodiment is meant according to ASTM D-696 measures the value that gets.For to obtain good effect, the difference of the thermal expansivity of described first laminate 101 and three ply board 103 is preferably 1 * 10 in the present embodiment
-5M/m ℃ or higher, more preferably 3 * 10
-5M/m ℃ or higher.In addition, from preventing to differ because of coefficient of thermal expansion the aspect consideration of this lamination structure generation slight crack that causes described light diffusing sheet too greatly, the coefficient of thermal expansion differences of described first laminate 101 and three ply board 103 is preferably 10 * 10
-5M/m ℃ or lower.
In order to satisfy the requirement of light diffusion, need in the resin of each laminate of described light diffusing sheet, add a certain amount of light diffusing agent, can increase the light diffusing of light diffusing sheet inside.As light diffusing agent, can use known particulate, be preferably partial cross-linked type siloxane polymer particle, acrylic polymers particle or the lime carbonate of 1 micron~10 microns of particle diameters.These diffusants can only use a kind of, also can use multiple.In addition, as other diffusant, can also and with inorganic fine particles such as barium sulphate, titanium dioxide, monox, talcum, white carbon, mica, glass, aluminium hydroxide, magnesium oxide, zinc paste and to these inorganic particulates apply surface treatment with fatty acid etc. and must material, the organic filler crosslinked or the high molecular weight styrene resin particle is such, but the above-mentioned preferred not enough light diffusing agent general assembly (TW) of diffusant as other 50%.
In addition, be provided with concavo-convexly by the surface that comprises first laminate 101 and three ply board 103 at described light diffusing sheet, then can give the exterior light diffusivity, and can reduce the consumption of light diffusing agent, also can increase the transmittance of light diffusing sheet.Simultaneously, the setting of concave-convex surface also can have good scratch resistance performance.Three ply board 103 mainly is to be the resin formation of principal ingredient with the polymethylacrylic acid in the light diffusing sheet in the present embodiment, has therefore well solved with projection and has produced friction and the problem of generation scuffing.
Owing to the effects such as resin variation, brightness reduction and color and luster variation that can cause light diffusing sheet from the light of back light, in order to improve photostability so preferably in described first laminate 101 and three ply board 103, mixing ultraviolet light absorber.Described ultraviolet light absorber comprises that benzophenone series ultraviolet light absorber, triazine are that ultraviolet light absorber, benzotriazole are that ultraviolet light absorber and cyclic imide base ester are one or more in the ultraviolet light absorber.
Described benzophenone series ultraviolet light absorber comprises 2; the 4-dihydroxy benaophenonel; 2-hydroxyl-4-methoxy benzophenone; 2-hydroxyl-4-octyloxy benzophenone; 2-hydroxyl-4-benzyloxy benzophenone; 2-hydroxyl-4-methoxyl-5-sulfonic acid benzophenone; 2-hydroxyl-4-methoxyl-5-sulfonic acid Trihydride benzophenone; 2; 2 '-dihydroxy-4-methoxyl benzophenone; 2; 2 '; 4; 4 '-tetrahydroxybenzophenone; 2; 2 '-dihydroxy-4; 4 '-dimethoxy-benzophenone; 2; 2 '-dihydroxy-4,4 '-dimethoxy-benzophenone-5-sodium sulfonate; two (5-benzoyl-4-hydroxyl-2-methoxyphenyl) methane; in 2-hydroxyl-4-dodecyl benzophenone and 2-hydroxyl-4-methoxyl-the 2 '-carboxyl benzophenone one or more.
Described triazine is that ultraviolet light absorber is 2-(4,6-diphenyl-1,3,5-triazines-2-the yl)-own oxygen base of 5-phenol.
Described benzotriazole is that ultraviolet light absorber comprises 2-(2-hydroxy-5-methyl base phenyl) benzotriazole; 2-(2-hydroxyl-uncle's 5-octyl phenyl) benzotriazole; 2-(2-hydroxyl-3; 5-two picryl phenyl) phenyl benzotriazole; 2-(the 2-hydroxyl-3-tert-butyl group-5-aminomethyl phenyl)-5-chlorobenzotriazole; 2; [4-(1 for 2 '-di-2-ethylhexylphosphine oxide; 1; 3; the 3-tetramethyl butyl)-6-(2H-benzotriazole-2-yl) phenol]; 2-(2-hydroxyl-3; the 5-di-tert-butyl-phenyl) benzotriazole; 2-(2-hydroxyl-3; the 5-di-tert-butyl-phenyl)-5-chlorobenzene third triazole; 2-(2-hydroxyl-3; the 5-di-tert-pentyl-phenyl) benzotriazole; 2-(2-hydroxyl-uncle's 5-octyl phenyl) benzotriazole; 2-(2-hydroxyl-5-tert-butyl-phenyl) benzotriazole; 2-(2-hydroxyl-4-octyloxyphenyl) benzotriazole; 2; 2 '-di-2-ethylhexylphosphine oxide (4-picryl-6-benzotriazole base phenyl); 2; 2 '-TOPOT 2,2 (1; 3-benzoxazine-4-ketone) and 2-[2-hydroxyl-3-(3; 4; 5,6-tetrahydrobenzene diformyl methyl)-and the 5-aminomethyl phenyl] in the benzotriazole one or more.
Described cyclic imide base ester is that ultraviolet light absorber comprises 2,2 '-TOPOT 2,2 (3,1-benzoxazine-4-ketone), 2,2 '-(4,4 '-diphenylene) two (3,1-benzoxazine-4-ketone) and 2, in 2 '-(2, the 6-naphthylene) two (3,1-benzoxazine-4-ketone) one or more.
When described light diffusing sheet is installed on the direct down type backlight LCD, the front side of described light diffusing sheet be described first laminate 101 towards the liquid crystal panel setting, the back side of described light diffusing sheet is that described three ply board 103 is towards the back light setting.
Fig. 2 is the structural representation of light diffusion plate for straight-down-type backlight LCD second embodiment of the present invention.As shown in Figure 2, be with Fig. 1 difference, described second laminate 102 comprise B1 layer, B2 layer ... the Bn layer, wherein, n 〉=2.Every layer in the described sandwich construction includes first kind resin, second resinoid and light diffusing agent, described B1 layer, B2 layer ... in the Bn layer first kind resin and the second resinoid weight ratio be respectively x1, x2 ... xn, wherein, x1>x2 ...>xn>0, and n 〉=2.Described B1 layer, B2 layer ... in the Bn layer first kind resin mix with second resinoid back thermal expansivity be respectively b1, b2 ... bn, b1<b2 ...<bn, wherein, n 〉=2, b1 is greater than the described first resinoid thermal expansivity, and bn is less than the described second resinoid thermal expansivity.Lamination order on the direction of described light diffusing sheet along liquid crystal panel towards back light be followed successively by first laminate 101, B1 layer, B2 layer ... Bn layer, three ply board 103.
The method for making of described light diffusing sheet can be the method for knowing altogether, and for example then method, solvent are followed method, method, cast polymerization method and surface coated method or the like are followed in polymerization for co-extrusion modling method, applying method, heating.
Light diffusing sheet of the present invention preferably passes through many extruder co-extrusion modlings of employing.After the resin of each laminate is weighed according to a certain ratio, by extruder fully mixing under molten condition separately, enter runner separately and in die head, converge, laminated for the molten resin plate after the one re-uses the roller set cooling curing, promptly finish this multilayer composite sheet.Use this method can make this multilayer board once-forming, avoided the compound production process of multiple tracks, consume to reduce to produce.In addition, owing to be that once-forming directly is composited, therefore layer is also more firm with combining of layer, and being difficult for influences use because of internal stress generation tomography and crack.
The light diffusing sheet that obtains thus is the tabular of 0.3 millimeter~4 millimeters of thickness with resin combination by extrusion molding.By directly its size that cuts into appointment being made light diffusing sheet of the present invention.The preferred thickness of described light diffusing sheet is 0.5 millimeter~3 millimeters, when 0.5 millimeter of thickness less than, is difficult to guarantee as the intensity of backlight with diffuser plate; When thickness surpasses 3 millimeters,, therefore be difficult to corresponding with maximization, slimming because diffuser plate weight becomes big.Wherein, described light diffusing sheet more preferably thickness be 1.0 millimeters~2.5 millimeters.
With eight embodiment and three comparative examples light diffusing sheet of the present invention is described in further detail below, described light diffusing sheet is by the be shaped laminated resin plate of 3 layers of formation obtaining of above-mentioned coextrusion.The light diffusing sheet that makes is carried out the mensuration of following performance parameter:
(1) thermal expansivity test
Test with the ASTM D-696 standard of being determined as.
(2) total light transmittance
With JIS K7136 is that standard is tested.
(3) mist degree
With JIS K7136 is that standard is tested.
(4) scratch resistance
Use having in the direct down type backlight cold-cathode tube LCD TV backlight of market sale, take out anti-warpage projection (by fire-retardant polycarbonate make, most advanced and sophisticated R=1mm), under the state of the load that applies 1000g described three ply board 103 surperficial reciprocating frictions 20 times.
(5) warp direction test
The light diffusing sheet that will expose 168 hours under 85 ℃ of 95%RH atmosphere is as for the 5300Cd/cm that has that equally spaced is arranged with 6 with 2.5cm is set
2On 46 inches straight back light units down of the cold-cathode tube of luminous energy, making picture part be in plumbness, is that backlight side is assembled in the position apart from cold-cathode tube 30mm with described three ply board 103.And then, the interval of 1.0mm is set on the outside of light diffusing sheet (side opposite with backlight side), utilize the thickness 1.5mm glass capsulation, the maintenance that have diameter 5mm hole 1 of central portion.Measure the glass of this moment and the distance (initial value) of diffuser plate.Cold-cathode tube is lit a lamp continuously, and the availability dial indicator is measured variation through the light diffusing sheet after 5 hours with the unit of 0.1mm, and record warpage maximal value, and protruding information slip to backlight side just is being shown, is being shown protruding information slip to glass side negative.
(6) anti-UV stability
Use with the acceleration light fastness test machine of metal halide light, use the optical filtering machine to see through wavelength region may: 295~350nm, operation mode as light source: Continuous irradiation, UV illumination: 77mW/cm2, the BP temperature: 60 ℃, humidity: 50%RH in the groove, spraying: do not have.Test period: 24 hours, the thin slice of use model thickness 2mm.Use beam split type colour meter, come the model after the fast light test is estimated with the Δ E that sees through light.
[embodiment 1]
At first, be 6 * 10 at thermal expansivity
-5Mix type siloxane polymer particle 1.5 mass parts and benzotriazole ultraviolet light absorber 5 mass parts in m/m ℃ polystyrene resin 100 mass parts, and drop in described first laminate, the 101 usefulness extruders as organic class light diffusing agent; Secondly, be 12 * 10 at thermal expansivity
-5Mix monox 2 mass parts and benzotriazole ultraviolet light absorber 5 mass parts in m/m ℃ plexiglass 100 mass parts, and drop in the described three ply board 103 usefulness extruders as the mineral-type light diffusing agent; At last, in the above-mentioned plexiglass of above-mentioned polystyrene resin that is respectively 50 mass parts and 50 mass parts, mix the above-mentioned type siloxane polymer particle of 3 mass parts and the above-mentioned monox of 1 mass parts, and drop in described second laminate, the 102 usefulness extruders, after carrying out fusion, get final product by the coextrusion shaping.The thickness of first laminate 101 described in the light diffusing sheet that makes is 0.5 millimeter, and the thickness of second laminate 102 is that 1 millimeter, the thickness of three ply board 103 are 0.5 millimeter, and the thickness of described light diffusing sheet is 2 millimeters.And, make described first laminate 101 and three ply board 103 surfaces have shaggy ridge design by the hot transfer printing of concavo-convex roller surface configuration.
For the light diffusing sheet that embodiment 1 makes, estimate total light transmittance, mist degree, surperficial scratch resistance, warp direction, anti-UV stability etc. by aforesaid method, its evaluation result is as shown in table 1.
[embodiment 2~8]
Thickness at described light diffusing sheet remains unchanged, under the prerequisite that each resin ratio and adjuvant addition remain unchanged in described first laminate 101, second laminate 102 and the three ply board 103, change the thickness of described first laminate 101, second laminate 102 and three ply board 103, change into respectively: embodiment 2 is for the thickness of described first laminate 101 is 0.3 millimeter, and the thickness of second laminate 102 is that 1 millimeter, the thickness of three ply board 103 are 0.7 millimeter; Embodiment 3 is for the thickness of described first laminate 101 is 0.2 millimeter, and the thickness of second laminate 102 is that 1.3 millimeters, the thickness of three ply board 103 are 0.5 millimeter; Embodiment 4 is for the thickness of described first laminate 101 is 0.1 millimeter, and the thickness of second laminate 102 is that 1.7 millimeters, the thickness of three ply board 103 are 0.2 millimeter; Embodiment 5 is for the thickness of described first laminate 101 is 0.3 millimeter, and the thickness of second laminate 102 is that 1.6 millimeters, the thickness of three ply board 103 are 0.1 millimeter; Embodiment 6 is for the thickness of described first laminate 101 is 0.6 millimeter, and the thickness of second laminate 102 is that 1.1 millimeters, the thickness of three ply board 103 are 0.3 millimeter; Embodiment 7 is for the thickness of described first laminate 101 is 0.7 millimeter, and the thickness of second laminate 102 is that 0.6 millimeter, the thickness of three ply board 103 are 0.7 millimeter; Embodiment 8 is for the thickness of described first laminate 101 is 0.5 millimeter, and the thickness of second laminate 102 is that 0.6 millimeter, the thickness of three ply board 103 are 0.9 millimeter.Method is similarly to Example 1 made light diffusing sheet, carries out the evaluation of each performance parameter, and its evaluation result is as shown in table 1.
[comparative example 1]
At thermal expansivity is 6 * 10
-5Mix type siloxane polymer particle 4 mass parts and benzotriazole ultraviolet light absorber 5 mass parts in m/m ℃ polystyrene resin 100 mass parts as organic class light diffusing agent, drop in described first laminate, the 101 usefulness extruders, carry out extrusion molding after the fusion, the thickness of the light diffusing sheet that makes is 2 millimeters, and by the hot transfer printing of concavo-convex roller surface configuration, make this light diffusing sheet both side surface have shaggy ridge design, the evaluation result of its each performance parameter is as shown in table 1.
[comparative example 2]
In the above-mentioned plexiglass of above-mentioned polystyrene resin that is respectively 50 mass parts and 50 mass parts, mix type siloxane polymer particle 4 mass parts and benzotriazole ultraviolet light absorber 5 mass parts as organic class light diffusing agent, drop in described second laminate, the 102 usefulness extruders, carry out extrusion molding after the fusion, the thickness of the light diffusing sheet that makes is 2 millimeters, and by the hot transfer printing of concavo-convex roller surface configuration, make this light diffusing sheet both side surface have shaggy ridge design, the evaluation result of its each performance parameter is as shown in table 1.
[comparative example 3]
At thermal expansivity is 12 * 10
-5Mix type siloxane polymer particle 4 mass parts and benzotriazole ultraviolet light absorber 5 mass parts in m/m ℃ plexiglass 100 mass parts as organic class light diffusing agent, drop in the described three ply board 103 usefulness extruders, carry out extrusion molding after the fusion, the thickness of the light diffusing sheet that makes is 2 millimeters, and by the hot transfer printing of concavo-convex roller surface configuration, make this light diffusing sheet both side surface have shaggy ridge design, the evaluation result of its each performance parameter is as shown in table 1.
Table one: the evaluation result of the performance parameter of eight embodiment and three comparative examples
|
Warp direction |
Scratch resistance |
Total light transmittance |
Mist degree |
Anti-UV |
Embodiment 1 |
??+ |
??◎ |
??◎ |
??○ |
??◎ |
Embodiment 2 |
??+ |
??◎ |
??◎ |
??○ |
??◎ |
Embodiment 3 |
??+ |
??◎ |
??◎ |
??◎ |
??◎ |
Embodiment 4 |
??+ |
??◎ |
??◎ |
??◎ |
??◎ |
Embodiment 5 |
??+ |
??◎ |
??◎ |
??◎ |
??◎ |
Embodiment 6 |
??+ |
??◎ |
??◎ |
??○ |
??◎ |
Embodiment 7 |
??+ |
??◎ |
??○ |
??△ |
??◎ |
Embodiment 8 |
??+ |
??◎ |
??○ |
??△ |
??◎ |
|
Warp direction |
Scratch resistance |
Total light transmittance |
Mist degree |
Anti-UV |
Comparative example 1 |
??- |
??△ |
??◎ |
??◎ |
??◎ |
Comparative example 2 |
??- |
??○ |
??◎ |
??◎ |
??◎ |
Comparative example 3 |
- |
??◎ |
??◎ |
??◎ |
??◎ |
Annotate: 1, warp direction refers to that light diffusing sheet is protruding to be just "+" to the back light direction, protruding to glass for bearing "-"; 2, the performance of " ◎ " expression light diffusing sheet performance functional, " △ " expression light diffusing sheet outstanding, " zero " expression light diffusing sheet is poor.
From the result of table 1 as can be seen, by the resin bed of stacked different heat expansion coefficient, the internal stress of resin bed can make light diffusing sheet to protruding direction warpage to back light, thereby has reached purpose of the present invention.
Light diffusing sheet of the present invention is the multilayer board that is made by two kinds of different resins of thermal expansivity, wherein this multiple-plate skin is made of the low thermal coefficient of expansion resin, internal layer is made of the high thermal expansion coefficient resin, the middle layer is made of with the resin combination that certain proportion mixes these two kinds of resins, and with by skin to the internal layer direction, thermal expansivity forms by ascending mode is laminated.Because under the influence of the heat of light source etc.,, can stipulate that it protrudes to high thermal expansion coefficient layer direction, the light source direction that promptly supports or opposes protrusion when light diffusing sheet because the internal stress that the difference of each layer thermal expansivity produces makes when this kind light diffusing sheet produces warpage.Described light diffusing sheet demonstrates good light diffusing and light fastness simultaneously.
The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.