CN101961940A

CN101961940A - Optical sheet for direct type liquid crystal display device and backlight unit

Info

Publication number: CN101961940A
Application number: CN2010102858856A
Authority: CN
Inventors: 长村惠弌
Original assignee: Jiro Enterprise Planning K K
Current assignee: Ewa Co., Ltd.
Priority date: 2009-06-04
Filing date: 2010-06-04
Publication date: 2011-02-02
Anticipated expiration: 2030-06-04
Also published as: CN101961940B; TWI434766B; KR101167231B1; JP2010282023A; TW201107136A; KR20100130969A

Abstract

The invention provides an optical sheet for a direct type liquid crystal display device capable of reducing the cost and being manufactured at good production rate and meanwhile being endued with high adhesiveness prevention and optical function. The optical sheet for the direct type liquid crystal display device comprises a transparent base material layer and an optical layer laminated on the surface side of the base material layer. The base material layer uses a double-axle tension polyester film containing filler and the average diameter of the filler is 70nm-200nm. The content of the filler is preferably 0.01wt%-1wt%. In addition, the filler is an inorganic particle such as silicon dioxide or an organic particle such as an acrylic resin. Preferably, the tension multiplying powder of the double-axle tension polyester film along the length direction is 2.5-4.5 times and the tension multiplying powder along the width direction is 3-5 times.

Description

Full run-down type liquid crystal display optical sheet and back light unit

Technical field

The present invention relates to the full run-down type liquid crystal display optical sheet and possess the back light unit that its full run-down type liquid crystal indicator is used.

Background technology

For LCD, its luminous mode backlight is popularized, the back light unit of side equipment edge illumination type, full run-down type etc. below liquid crystal layer.Particularly,, consider, preferably use the Staight downward type backlight unit from the inhomogeneity viewpoint that keeps the brightness whole as the back light unit that big view display is used.This Staight downward type backlight unit 50 possesses backlight 52, the various optical sheets that are equipped on backlight 52 face side that have as a plurality of lamps 51 of light source basically shown in Fig. 6 (a).As this optical sheet, for example be equivalent to be equipped on backlight 52 face side light diffusing sheet 53, be equipped on the prismatic lens 54 etc. of the face side of light diffusing sheet 53.

The function of this Staight downward type backlight unit 50 is washed bright, at first inject light diffusing sheet 53, spread, penetrate from light diffusing sheet 53 surfaces by light diffusing sheet 53 from backlight 52 light that send.Then, inject prismatic lens 54, show that in normal direction the light of the distribution at peak penetrates as basic by the 54a of prism portion that is formed at prismatic lens 54 surfaces from the light that light diffusing sheet 53 penetrates.

Like this, spread by light diffusing sheet 53,, show that in normal direction ground, peak reflects substantially, further to whole illumination of the liquid crystal layer (not shown) of face side in addition by prismatic lens 54 from backlight 52 light that penetrate.What illustrated is; though it is not shown; but with the adhesion of the liquid crystal panel of the protection of the mitigation of the optically focused characteristic of above-mentioned prismatic lens 54, the 54a of prism portion or polarizer etc. and prismatic lens 54 prevent to be purpose, further set optical sheet in the face side of prismatic lens 54.

As the light diffusing sheet 53 that possesses in the above-mentioned back light unit 50, general as Fig. 6 (b) shown in, use has transparent substrate layer 55, in binding agent 58, be dispersed with the light diffusion layer 56 of light diffusing agent 59, in binding agent 60, be dispersed with the bead coating-type that prevents adhesion layer 57 of bead 61 light diffusing sheet (for example with reference to the spy open flat 7-5305 communique, the spy opens 2000-89007 communique etc.).In addition, replace the coating bead, also use with have the light diffusing sheet of the mould of concaveconvex shape at the pattern pressing type of this concaveconvex shape of surface transfer of transparent substrate layer (for example with reference to the spy open the 2006-47608 communique, the spy opens 2006-335028 communique etc.).The light diffusing sheet of these types realizes carrying out light diffusion function by the fine concaveconvex shape on surface.

This light diffusing sheet 53 is generally made by the following: carry out from the T die head to fusion thermoplastic resin carry out the step of extrusion molding, then this extrusion molding body stretched and forms the operation of base material film at film length direction and film width, carry out then preventing that with what in binding agent, be dispersed with bead adhesion layer is with the composition operation stacked at the back side of base material film and will be dispersed with the surperficial stacked operation of the light diffusion layer usefulness composition of light diffusing agent at base material film in binding agent.In this gimmick, prepare in advance and prevent adhesion layer composition and light diffusion layer composition, in the production line different with the film formed production line of base material, these compositions are stacked gradually in base material film (owing to comprising that the film formed production line of base material and the stacked production line of stretching process are separately, so be called the off-line layered manner).But in the manufacture method of the light diffusing sheet of the so a plurality of production lines of needs, manufacturing cost increases, and in addition, it is miscellaneous that manufacturing process becomes, and therefore produces rough sledding aspect productivity ratio, operating efficiency.

[technical literature formerly]

[patent documentation]

[patent gazette 1]: the spy opens flat 7-5305 communique

[patent gazette 2]: the spy opens the 2000-89007 communique

[patent gazette 3]: the spy opens the 2006-47608 communique

[patent gazette 4]: the spy opens the 2006-335028 communique

Summary of the invention

The problem that invention will solve

The present invention makes in view of these rough sledding, the back light unit that purpose is to provide a kind of full run-down type liquid crystal display optical sheet and possesses it, while described optical sheet can suppress that cost, productivity ratio made, be endowed simultaneously height well prevent adhesiveness and optical function.

Be used to solve the means of problem

The invention of making in order to solve above-mentioned problem is the full run-down type liquid crystal display optical sheet, its be possess transparent substrate layer, at the full run-down type liquid crystal display optical sheet of the stacked optical layers of the face side of this substrate layer, it is characterized in that:

As above-mentioned substrate layer, use the biaxially oriented polyester film that contains filler,

The average grain diameter of this filler is 70nm～200nm.

According to this full run-down type liquid crystal display optical sheet, substrate layer as optical sheet, use contains the biaxially oriented polyester film of filler, filler particles reaches on the polyester based resin face at substrate layer that exists around it and gives prominence to thus, and this ledge is for the adhesion function of bringing into play at other stacked layer of the rear side of substrate layer highly that prevents.Therefore, this full run-down type liquid crystal display optical sheet is not in addition stacked to be prevented adhesion layer and has the adhesion function of preventing, thus, do not need to carry out the stacked operation at the off-line that carries out (off line) all the time, the reduction of manufacturing cost and the efficient activity of manufacturing process become possibility.In addition, particularly for the large-area optical sheet that in the big picture of full run-down type liquid crystal indicator, uses, can realize the significantly reduction of manufacturing cost and the simplification of manufacturing process.

As the filler that in substrate layer, contains of this full run-down type liquid crystal display optical sheet,, can obtain the transparency that prevents adhesion function and excellence of height by using the filler of average grain diameter 70nm～200nm.Promptly, by contain average grain diameter in substrate layer is filler more than the 70nm, the ledge that forms specified altitude on the face of substrate layer becomes possibility, can not be provided with and prevent that adhesion layer ground from effectively presenting for the adhesion function that prevents at other stacked layer of the rear side of substrate layer.It is a filler below the 200nm by contain average grain diameter in substrate layer on the other hand, can provide performance such preventing adhesion function, have an optical sheet of the excellent transparency simultaneously.In addition, like this, be the filler below the 200nm, can prevent the reduction of mechanical strength of the hot strength etc. of optical sheet by using average grain diameter.

The preferred 0.01 quality % of the content of the above-mentioned filler in the substrate layer～1 quality %.By using filler with such content, the performance height prevent adhesion function in, the mechanical strength that obtains the excellent transparency and hot strength etc. becomes possibility.That is, be more than the 0.01 quality % by the content that makes the filler in the substrate layer, can on the face of substrate layer, form most ledges, therefore can present fully and prevent adhesion function.On the other hand, be below the 1 quality % by the content that makes the filler in the substrate layer, while bring into play preventing adhesion function, the transparency is remained on the reduction that excellent level, while suppress the mechanical strength of optical sheet effectively becoming possibility of height.

Above-mentioned filler can be selected from the group of being made up of silica, aluminium oxide, titanium dioxide, calcium carbonate, kaolin, barium sulfate, acrylic resin, melmac, organic siliconresin and crosslinked polystyrene.As the filler that contains in the substrate layer; use these inorganic particles or organic fine particles; can make the ledge that on the face of substrate layer, forms have to a certain degree intensity thus, therefore can present effectively for the adhesion function that prevents at other stacked layer of the rear side of substrate layer.In addition, by these filler compositions that use has above-mentioned average grain diameter, can keep the high transparent of substrate layer.And then as the filler composition that contains in substrate layer, by using the inorganic constituents of silica, aluminium oxide, titanium dioxide, calcium carbonate, kaolin or barium sulfate, hear resistance and the resistance to water of strengthening substrate layer become possibility.

Preferred 2.5 times～4.5 times of the stretching ratio of the length direction of the biaxially oriented polyester film that uses as substrate layer, preferred 3 times～5 times of the stretching ratio of width.Be set in more than 2.5 times, and the stretching ratio of width be set in more than 3 times by the stretching ratio with the length direction of biaxially oriented polyester film, filler particles and the polyester based resin composition that exists on every side thereof are outstanding fully on the face of substrate layer.And this ledge contacts with the surface of other layer of the rear side that is laminated in optical sheet, can prevent the adhesion of substrate layer and other layer thus effectively.In addition, be set in below 4.5 times and the stretching ratio of width is set in below 5 times by stretching ratio the length direction of biaxially oriented polyester film, can prevent adhesion function simultaneously what obtain height, keeping of the inhibition of the excessive filming of film and mechanical strength becomes possibility.

Length direction and the F5 value of width, the preferably 80MPa～120MPa of the biaxially oriented polyester film that uses as substrate layer.Be set in by F5 value in the scope of value of afore mentioned rules the length direction of biaxially oriented polyester film and width, the distortion that tension force in the time of can suppressing processing of films causes, simultaneously prevent the generation of the fold that ripple is tabular, with filler particles and the face of the substrate layer beyond the ledge that causes of the polyester based resin that exists on every side maintain level and smooth state, make the adhesion function optimization that prevents that realizes by this ledge become possibility.What illustrated is, " the F5 value " among the application is meant under 25 ℃ the stress of this direction when giving 5% stretcher strain as the film of object.

The confficient of static friction of the biaxially oriented polyester film that uses as substrate layer is preferably 0.3～0.6, the coefficient of kinetic friction is preferably 0.3～0.5, by the confficient of static friction that makes biaxially oriented polyester film is more than 0.3 and to make the coefficient of kinetic friction be more than 0.3, substrate layer that the protuberance branch that forms on the face of substrate layer by filler particles etc. causes and the friction of other layer fully become big, thus, can bring into play the adhesion function that prevents effectively for other layer of substrate layer.In addition, by the confficient of static friction that makes biaxially oriented polyester film is below 0.6 and to make the coefficient of kinetic friction be below 0.5, while can obtain bringing into play the face that prevents the substrate layer beyond adhesion function, the above-mentioned ledge of height and thereon other stacked layer the abundant driving fit of face, stable structure.

The average thick I of arithmetic average roughness (Suan Intraoperative of the biaxially oriented polyester film that uses as substrate layer) (Ra) be 0.04 μ m～0.25 μ m.By the arithmetic average roughness (Ra) that makes biaxially oriented polyester film is more than the 0.04 μ m, and filler particles and the polyester based resin composition that exists on every side thereof are outstanding fully on the face of substrate layer, realize the excellent adhesion function that prevents.In addition, be below the 0.25 μ m by the arithmetic average roughness (Ra) that makes biaxially oriented polyester film, while can bring into play preventing adhesion function, moderately keeping substrate layer and the adaptation of other stacked layer thereon of height.

In addition, the maximal roughness (maximum thick I) of the biaxially oriented polyester film that uses as substrate layer (Ry) is preferably 0.4 μ m～0.8 μ m, and 10 mean roughness (10 average thick I) (Rz) are preferably 0.3 μ m～0.6 μ m.Be the value in the above-mentioned scope by maximal roughness (Ry) or 10 mean roughness (Rz) that make biaxially oriented polyester film, prevent adhesion function, the while that can obtain excellence are moderately kept the adaptation of substrate layer and other layer.

The optical layers of this full run-down type liquid crystal display optical sheet can have light diffusing agent and its binding agent.By possessing the optical sheet of the optical layers that contains this light diffusing agent and its binding agent, can make optically focused, improve to the optical function of the refraction of normal direction side, diffusion etc.In addition, above-mentioned optical layers also can contain and has refrangible fine concaveconvex shape, by possessing the optical sheet of the optical layers with so fine concaveconvex shape, can make the control facilitation of light diffusing when improving light diffusing.In addition owing to do not need to form in addition optical layers, therefore make optical sheet more filming become possibility.

Therefore, the back light unit that the full run-down type liquid crystal indicator of introducing face side is used in that the light that sends from lamp is disperseed, if possess this optical sheet, the biaxially oriented polyester film that contains the filler of average grain diameter by use with regulation, can keep the transparency on one side, suppress the back side of substrate layer and the adhesion of other layer on one side effectively, the reduction of manufacturing cost and the efficient activity of manufacturing process become possibility simultaneously.In addition, this optical sheet is by possessing the optical layers that contains light diffusing agent and its binding agent, can bring into play optically focused, to the optical function of the excellence of the refraction of normal direction side, diffusion etc.

The effect of invention

As above illustrated, according to full run-down type liquid crystal display optical sheet of the present invention, because filler particles and the polyester based resin that exists on every side thereof are outstanding on the face of substrate layer, this ledge is for the adhesion function that prevents at stacked other layer performance height of the rear side of optical sheet, therefore do not need the stacked operation that prevents adhesion layer of the off-line that all the time carries out, the reduction of manufacturing cost and the efficient activity of manufacturing process become possibility.In addition,,, can obtain the adhesion function that prevents of height, obtain the excellent transparency simultaneously, in addition, can prevent the reduction of mechanical strength by using the filler of average grain diameter as 70nm～200nm as the filler that in substrate layer, contains.

Description of drawings:

The schematic cross sectional views of the full run-down type liquid crystal display optical sheet that Fig. 1 relates to for an embodiment of the invention.

Fig. 2 is the flow chart of the manufacture method of the full run-down type liquid crystal display optical sheet of demonstration Fig. 1.

Fig. 3 is the schematic diagram of the manufacturing thing of each step of the manufacture method of demonstration Fig. 2.

Fig. 4 is for showing the schematic representation of apparatus of the manufacture method be used to implement Fig. 2.

The schematic cross sectional views of the full run-down type liquid crystal display optical sheet that Fig. 5 relates to for the embodiment different with Fig. 1;

Fig. 6 (a) is for showing the perspective schematic view of general Staight downward type backlight unit, (b) for showing the schematic cross sectional views of general light diffusing sheet in the past.

The explanation of symbol:

1 optical sheet

2 substrate layers

3 optical layers

4 polyester based resins

5 fillers

6 light diffusing agents

7 binding agents

The mixture of 8 polyester based resins 4 and filler 5

9 base material film squeeze-ups

10 contain the optical layers composition of light diffusing agent 6 and binding agent 7

11 optical sheets

12 fine concaveconvex shapes

The 20T die head

21 a pair of compression rollers

22 stretching devices

23 coating disks

The 24a pick-up roll

24b adjusts roller

The 24c applicator roll

The 24d backing roll;

50 back light units

51 lamps

52 is backlight

53 light diffusing sheets

54 prismatic lenses

54a prism portion

55 substrate layers

56 light diffusion layers

57 prevent adhesion layer

58 binding agents

59 light diffusing agents

60 binding agents

61 beads

The specific embodiment

Following one side suitably is elaborated to embodiments of the present invention on one side with reference to accompanying drawing.

The optical sheet 1 that full run-down type liquid crystal indicator shown in Figure 1 is used mainly has transparent substrate layer 2, reaches in the stacked optical layers 3 of the face side of this substrate layer.

Transparent substrate layer 2 is served as reasons, and to contain average grain diameter be the biaxially oriented polyester film that the polyester based resin 4 of the filler 5 of 70nm～200nm constitutes.On the face of substrate layer 2, be formed with the particle of most fillers 5 and the ledge of polyester based resin on every side 4 thereof.

Constitute the polyester based resin 4 of substrate layer 2, light is seen through, therefore require the transparency.As this polyester based resin 4, as long as just there is no particular limitation to have the transparency, for example can enumerate: terephthalic acid (TPA), M-phthalic acid, phthalic acid, 2, the 5-naphthalenedicarboxylic acid, 2, the 6-naphthalenedicarboxylic acid, 1, the 4-naphthalenedicarboxylic acid, 1, the 5-naphthalenedicarboxylic acid, the diphenyl carboxylic acid, the biphenoxyl ethane dicarboxylic acids, the diphenyl sulfone carboxylic acid, the anthracene dioctyl phthalate, 1,3-pentamethylene dicarboxylic acids, 1, the 3-cyclohexane dicarboxylic acid, 1, the 4-cyclohexane dicarboxylic acid, six hydrogen terephthalic acid (TPA)s, six hydrogen M-phthalic acids, malonic acid, dimethyl malonic acid, butanedioic acid, 3,3-diethyl butanedioic acid, glutaric acid, 2, the 2-dimethylated pentanedioic acid, adipic acid, 2-methyl adipic acid, trimethyladipic acid, pimelic acid, azelaic acid, dimeric dibasic acid, decanedioic acid, suberic acid, at least a in the dicarboxylic acids of dodecanedicarboxylic acid etc.; With ethylene glycol, propane diols, hexamethylene glycol, dimethyltrimethylene glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, ten aklylene glycols, 1, ammediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexylene glycol, 2, homopolymers or copolymer that at least a bunching in the glycol of two (4-hydroxy phenyl) propane of 2-, two (4-hydroxy phenyl) sulfone etc. forms, or with this homopolymers, copolymer blended material more than 2 kinds.Wherein, preferably clear excellence, PETG that intensity is high, polybutylene terephthalate (PBT), poly-2,6-(ethylene naphthalate), preferred especially PETG.PETG can pass through for example following generation, promptly, dimethyl terephthalate (DMT) and ethylene glycol are packed in the reactor, improving internal temperature at leisure carries out ester exchange reaction on one side on one side, then reaction product is moved on in the polymer reactor, under high-temperature vacuum, carry out polymerisation.

Filler 5 as substrate layer 2 is contained as long as average grain diameter is that 70nm～200nm just has no particular limits, can use known inorganic particles, organic fine particles.Preferred example as filler 5, can enumerate silica, aluminium oxide, titanium dioxide, calcium carbonate, kaolin, barium sulfate, acrylic resin, melmac, organic siliconresin, crosslinked polystyrene, because by using these specific fillers 5, making ledge on the face that is formed at substrate layer 2 have to be used to bring into play to prevent adhesion function fully and the intensity of necessary degree, therefore can suppress of the adhesion of other layer effectively for substrate layer 2.In addition, have these fillers 5 of the average grain diameter of regulation by use, can keep necessary high transparent as optical sheet.And, use the inorganic particles of silica, aluminium oxide, titanium dioxide, calcium carbonate, kaolin, barium sulfate as filler 5, can strengthen the hear resistance, resistance to water, impact strength, hot strength of substrate layer etc. thus.

The average grain diameter of filler 5 is 70nm～200nm.The polyester based resin 4 of the filler 5 that contains the particle diameter with such scope is carried out biaxial stretch-formed and forms substrate layer 2, and the particle of filler 5 is outstanding on the face of substrate layer 2 with the polyester based resin 4 that exists around it thus, forms most ledges.The ledge of such majority is brought into play the function that prevents in the adhesion (stickup) of the layer of stacked other of the rear side of substrate layer 2 effectively.That is, be more than the 70nm by the average grain diameter that makes the filler 5 that in substrate layer 2, contains, form the ledge of appropriateness height, prevent effectively and the stickup of other layer that raising prevents adhesion function.In addition; by the average grain diameter that makes the filler 5 that contains in substrate layer 2 is below the 200nm; can form the ledge of the abundant size that realizes preventing adhesion function on one side; guarantee the transparency of the excellence of substrate layer 2 on one side; prevent the reduction of matrix (matrix) function that polyester based resin 4 causes simultaneously, highly keep the mechanical strength of the hot strength etc. of optical sheet integral body.And, be below the above-mentioned higher limit by the average grain diameter that makes the filler 5 that in substrate layer 2, contains, for the rear side of substrate layer 2 the damage of stacked other layer be suppressed.The average grain diameter of filler 5 can and then be preferably 100nm～150nm.

The content of the filler 5 in the substrate layer 2; as long as guarantee substrate layer 2 the transparency, realize the desired adhesiving effect that prevents, just have no particular limits preferred 0.01 quality %～1 quality %; further preferred 0.05 quality %～0.8 quality %, most preferably 0.08 quality %～0.4 quality %.By the content that makes the filler 5 in the substrate layer 2 is more than the 0.01 quality %, can make that the particle of filler 5 and polyester based resin on every side 4 thereof cause ledge on the face of substrate layer 2, form mostly, therefore prevent that fully presenting of adhesion function from becoming possibility.In addition, be below the 1 quality % by the content that makes the filler 5 in the substrate layer 2, can balance reach well height prevent adhesion function, as the keeping of the desired transparency of optical sheet, and the maintenance of high mechanical strength.

Preferred 2.5 times～4.5 times of the stretching ratio of the length direction of the biaxially oriented polyester film that uses as substrate layer 2, preferred 3 times～5 times of the stretching ratio of width.Be set in more than 2.5 times and the stretching ratio of width is set in more than 3 times by stretching ratio, most local outstanding on 2 of substrate layers after the stretching of filler 5 and the polyester based resin 4 that exists on every side thereof with sufficient size with the length direction of biaxially oriented polyester film.This most ledge contacts with surface at other stacked layer of the rear side of optical sheet, prevents the excessive driving fit of substrate layer and other layer thus, realizes preventing adhesiving effect.And then, be set in below 4.5 times and the stretching ratio of width is set in below 5 times by stretching ratio the length direction of biaxially oriented polyester film, what can present height prevents adhesiving effect, prevent simultaneously the surplus that the filming of film causes ledge formation and follow the reduction of its mechanical strength.

The length direction of the biaxially oriented polyester film that uses as substrate layer 2 and the preferred 80MPa～120MPa of F5 value of width, further preferred 90MPa～110MPa.The F5 value of length direction and width is obtained as following value: i.e. the sample that cuts out for the central portion from substrate layer 2 (biaxially oriented polyester film), method based on the JIS-Z1702 regulation, use cupping machine, under 23 ℃, the room temperature of 65%RH, speed with draw speed 300mm/ minute, when length direction or width stretching, the stress that the sample of mensuration specific elongation rate 5% applies, the value that gets divided by the sectional area of sample.Under the situation of F5 value less than 80MPa of the length direction of biaxially oriented polyester film, add easy deformation when being expert at the direction load tension man-hour in the demoulding of film.In addition, under the situation of F5 value less than 80MPa of the width of biaxially oriented polyester film, the hardness of film (コシ) reduces, and produces the continuous tabular fold of ripple at direction of travel easily.The length direction by making biaxially oriented polyester film and the F5 value of width then can prevent these rough sledding for more than the 80MPa.In addition, by distortion, the fold that prevents film like this, the face of the substrate layer 2 beyond the ledge that be produced by filler 5 and polyester based resin 4 of existing around it can be remained level and smooth state, make by what this ledge was realized and prevent the adhesion function optimization.On the other hand, the length direction by making biaxially oriented polyester film and the F5 value of width can suitably keep flexibility, processability, the durability of film below the 120MPa or below the 110MPa.

The confficient of static friction of the biaxially oriented polyester film that uses as substrate layer 2 is preferred 0.3～0.6, the coefficient of kinetic friction preferred 0.3～0.5.The confficient of static friction of biaxially oriented polyester film and the coefficient of kinetic friction are measured based on the method for JIS-K7125 regulation.Confficient of static friction by making biaxially oriented polyester film is more than 0.3 and make the coefficient of kinetic friction more than 0.3, because the ledge of the majority of the filler 5 that forms on the face of substrate layer 2 and the polyester based resin 4 that exists on every side thereof, substrate layer becomes fully big with the friction of other stacked layer thereon.Its result brings into play the adhesion of other layer for basic unit effectively.In addition, confficient of static friction by making biaxially oriented polyester film is below 0.6 and make the coefficient of kinetic friction below 0.5, give full play to the adhesiving effect that prevents of above-mentioned ledge generation, the face of the substrate layer beyond these ledges of while contacts reliably with the face of other stacked thereon layer, obtains stable laminate structure.And then the coefficient of kinetic friction by making biaxially oriented polyester film can add the generation that prevents fold, damage man-hour at film below 0.5, suppresses presenting of uneven optical characteristics.

The arithmetic average roughness (Ra) of the biaxially oriented polyester film that uses as substrate layer 2 is preferably 0.04 μ m～0.25 μ m, more preferably 0.05 μ m～0.15 μ m.More than arithmetic average roughness (Ra) the 0.04 μ m that makes biaxially oriented polyester film, the polyester based resin 4 of filler 5 and existence on every side thereof with highly outstanding fully, can prevent for the adhesion at other stacked layer of the rear side of substrate layer 2 on the face of substrate layer 2 effectively.In addition, below arithmetic average roughness (Ra) the 0.25 μ m that makes biaxially oriented polyester film, can bring into play the adhesiving effect that prevents that the ledge of filler 5 grades produces fully, simultaneously the face of the substrate layer beyond these ledges and the adaptation of the face of other stacked layer thereon be maintained suitable level.

And then the maximal roughness (Ry) of the biaxially oriented polyester film that uses as substrate layer 2 is preferably 0.4 μ m～0.8 μ m.In addition, 10 mean roughness (Rz) of the biaxially oriented polyester film that uses as substrate layer 2 are preferably 0.3 μ m～0.6 μ m.Be the value in the above-mentioned scope by maximal roughness (Ry) and 10 mean roughness (Rz) that make biaxially oriented polyester film, on the face of substrate layer 2, loose some ground and of filler 5 and the polyester based resin 4 that exists on every side thereof with highly outstanding fully, can obtain the adhesiving effect that prevents of height, simultaneously the adaptation between substrate layer and other layer be maintained suitable level.

The thickness of substrate layer 2 (average thickness) has no particular limits, and for example is 10 μ m～500 μ m, preferred 35 μ m～250 μ m, preferred especially 50 μ m～188 μ m.If that the thickness of substrate layer 2 less than above-mentioned scope, then is easy to generate when coating is used to form the resin combination of optical layers 3 is curling, handle the rough sledding of the difficulty that becomes etc.Otherwise if the thickness of substrate layer 2 surpasses above-mentioned scope, then the brightness of liquid crystal indicator reduces, and the thickness of back light unit becomes big in addition, and is also opposite with the requirement of the slimming of liquid crystal indicator.

Possess a plurality of light diffusing agent 6 that sets substantially equably on the surface of substrate layer 2 and the binding agent 7 of this a plurality of light diffusing agent 6 in the stacked optical layers 3 of the face side of substrate layer.This a plurality of light diffusing agent covers for 6 bonded doses 7.Make by a plurality of light diffusing agent 6 that is contained in the optical layers 3 like this to see through optical layers 2 from dorsal part and spread equably, make optically focused simultaneously, improve to the optical function of the refraction of normal direction etc. to the light of table side.In addition, be formed uniformly substantially on the surface of optical layers 3 by a plurality of light diffusing agent 6 fine concavo-convex.Pass through refraction action like this, light is spread more well at the fine concavo-convex lens of the surface of optical sheet 1 formation.What illustrated is that there is no particular limitation for the average thickness of optical layers 3, for example, is about 1 μ m～30 μ m.

Light diffusing agent 6 roughly is divided into inorganic filler and organic filler for having the particle of the character that makes the light diffusion.As inorganic filler, can use for example silica, aluminium hydroxide, aluminium oxide, zinc oxide, barium sulphide, magnesium silicate or their mixture.As the material of organic filler, can use for example acrylic resin, acrylonitrile resin, polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile, polyamide etc.Wherein, the acrylic resin that preferably clear is high, preferred especially polymethyl methacrylate (PMMA).

Shape as light diffusing agent 6 has no particular limits, and can exemplify for example spherical, spindle shape, needle-like, shaft-like, cubic, tabular, flakey, fibrous etc., wherein, and the spherical bead of preferred light diffusivity excellence.

As the lower limit of the average grain diameter of light diffusing agent 6, preferred 1 μ m, preferred especially 2 μ m, more preferably 5 μ m.On the other hand, as the upper limit of the average grain diameter of light diffusing agent 6, preferred 50 μ m, preferred especially 20 μ m, more preferably 15 μ m.If the average grain diameter of light diffusing agent 6 is less than above-mentioned scope, then the concavo-convex of optical layers 3 surfaces that probably forms by light diffusing agent 6 diminishes, do not satisfy as the necessary light diffusing of light diffusing sheet.Otherwise if the average grain diameter of light diffusing agent 6 surpasses above-mentioned scope, then the thickness of optical sheet 1 increases and the uniform difficulty that becomes that spreads.

As the use level of light diffusing agent 6 lower limit of (solid as 100 parts of the substrate polymers in the polymer composition of the formation material of binding agent 7 divides the use level that converts relatively), preferred 10 parts, preferred especially 20 parts, more preferably 50 parts, the upper limit as this use level, preferred 500 parts, preferred especially 300 parts, more preferably 200 parts.This be because: if the use level of light diffusing agent 6 less than above-mentioned scope, then light diffusing becomes insufficient, on the other hand, if the use level of light diffusing agent 6 surpasses above-mentioned scope, then the effect of fixed light diffusant 6 reduces.What illustrated is, on the what is called that the face side of prismatic lens sets with under the situation of light diffusing sheet owing to do not need high light diffusing, therefore as the use level of light diffusing agent 6, preferred 10 parts～40 parts, preferred especially 10 parts～30 parts.

Binding agent 7 forms by making the polymer composition that contains substrate polymer carry out crosslinking curing.Light diffusing agent 6 is fixing with essentially identical density configuration by this binding agent 7 on the surface of substrate layer 2.What illustrated is, for the polymer composition that is used to form binding agent 7, except substrate polymer, also can suitably cooperate for example small inorganic filler, curing agent, plasticizer, dispersant, various levelling agent, ultra-violet absorber, antioxidant, viscosity modification agent, lubricant, light stabilizer etc.

As above-mentioned substrate polymer, have no particular limits, can enumerate for example acrylic resin, polyurethane, polyester, fluorine resin, silicon-type resin, polyamidoimide, epoxy resin, ultraviolet curing resin etc., mixing more than a kind or 2 kinds of these polymer can be used.Particularly, as above-mentioned substrate polymer, preferred processability height, can easily form the polyalcohol of optical layers 3 by the means of coating etc.In addition,, consider preferably clear, preferred especially water white transparency from the radioparent viewpoint that improves light for the substrate polymer that is used for binding agent 7 self.

As above-mentioned polyalcohol, can enumerate the unsaturated monomer that for example will contain hydroxyl the monomer component polymerization and polyalcohol, the PEPA that under the condition of hydroxyl surplus, obtains etc., can be separately or mix more than 2 kinds and use with them.

As the unsaturated monomer of hydroxyl, for example can enumerate (a), acrylic acid 2-hydroxyl ethyl ester, acrylic acid 2-hydroxypropyl acrylate, methacrylic acid 2-hydroxyl ethyl ester, methacrylic acid 2-hydroxypropyl acrylate, allyl alcohol, homoallylic alcohol, cinnamyl alcohol, the unsaturated monomer of the hydroxyl of crotonyl alcohol etc.; (b) for example by ethylene glycol, oxirane, propane diols, expoxy propane, butanediol, epoxy butane, 1, the 2 yuan of alcohol of two (methylol) cyclohexanes of 4-, phenyl glycidyl ether, glycidyl decylate, プラ Network セ Le FM-1 (by ダイセ Le chemical industry Co., Ltd. system) etc. or epoxide, the unsaturated monomer of the hydroxyl that obtains with the reaction of for example unsaturated carboxylic acid of acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid etc. etc.The polymerization of selecting of carrying out more than a kind or 2 kinds can be made polyalcohol from the unsaturated monomer of these hydroxyls.

In addition, above-mentioned polyalcohol also can be made with the polymerization of unsaturated monomers that is selected from above-mentioned (a) and hydroxyl (b) by being selected from the following ethylenically unsaturated monomer more than a kind or 2 kinds: ethyl acrylate, the acrylic acid n-propyl, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, EHA, EMA, n propyl methacrylate, isopropyl methacrylate, n-BMA, the metering system tert-butyl acrylate, ethylhexyl methacrylate, GMA, cyclohexyl methacrylate, styrene, vinyltoluene, the 1-methyl styrene, acrylic acid, methacrylic acid, acrylonitrile, vinylacetate, propionate, stearic acid vinyl ester, allyl acetate, diallyl adipate, the itaconic acid diallyl, diethyl maleate, vinyl chloride, vinylidene chloride, acrylamide, N hydroxymethyl acrylamide, N-butoxymethyl acrylamide, diacetone acrylamide, ethene, propylene, isoprene etc.

To contain hydroxyl unsaturated monomer the monomer component polymerization and the number-average molecular weight of the polyalcohol that obtains is 1000～500000, preferred 5000～100000.In addition, its hydroxyl value is 5～300, and is preferred 10～200, more preferably 20～150.

The PEPA that under the condition of hydroxyl surplus, obtains, can be with (c) ethylene glycol for example, diethylene glycol (DEG), propane diols, DPG, 1, the 3-butanediol, 1, the 4-butanediol, 1, the 5-pentanediol, neopentyl glycol, hexamethylene glycol, the decamethylene glycol, 2,2,4-trimethyl-1, the 3-pentanediol, trimethylolpropane, hexanetriol, glycerine, pentaerythrite, cyclohexane diol, hydrogenated bisphenol A, two (methylol) cyclohexane, hydroquinones two (hydroxyethyl ether), three (ethoxy) isocyanuric acid ester, the polyalcohol of benzene dimethanol etc. is with (d) maleic acid for example, fumaric acid, butanedioic acid, adipic acid, decanedioic acid, azelaic acid, trimellitic acid, terephthalic acid (TPA), phthalic acid, the polyacid of M-phthalic acid etc. is at propane diols, hexylene glycol, polyethylene glycol, under the condition more than the carboxyl number of the above-mentioned polyacid of hydroxyl value in the polyalcohol of trimethylolpropane etc. the reaction and make.

The number-average molecular weight of the PEPA that obtains under the condition of this hydroxyl surplus is 500～300000, preferred 2000～100000.In addition, this hydroxyl value is 5～300, and is preferred 10～200, more preferably 20～150.

As polyalcohol, preferably above-mentioned PEPA and the above-mentioned monomer component that contains the unsaturated monomer of hydroxyl are carried out polymerization and obtain and have the acrylic compounds polyalcohol of (methyl) acryloyl unit etc. as the substrate polymer of this polymer composition.As the weatherability height of the binding agent 7 of substrate polymer, can suppress the flavescence of optical layers 3 etc. with this PEPA or acrylic compounds polyalcohol.What illustrated is, can use any one in the pure and mild acrylic compounds polyalcohol of this polyester polyols, also can use both.

What illustrated is, if the number of the hydroxyl in above-mentioned PEPA and the acrylic compounds polyalcohol is that per 1 molecule is more than 2, then have no particular limits, if but the hydroxyl value in the solid branch is below 10, the then crosslinked minimizing of counting, the tunicle rerum natura of solvent resistance, resistance to water, hear resistance, case hardness etc. has the tendency of reduction.

Can in the polymer composition that forms binding agent 7, contain small inorganic filler.By contain small inorganic filler in binding agent 7, the hear resistance of optical layers 3 and then optical sheet 1 improves like this.Inorganic matter as constituting this small inorganic filler has no particular limits, preferred inorganic oxide.This inorganic oxide is defined as metallic element has mainly constituted the network of 3 dimensions via the key with oxygen atom various oxygen metal compound.As the metallic element that constitutes inorganic oxide, preference more preferably is selected from the element of the periodic table of elements the 3rd family～the 5th family as being selected from the element of the periodic table of elements the 2nd family～the 6th family.Be preferably selected from the element of Si, Al, Ti and Zr especially, hear resistance improve effect and uniformly dispersed aspect, the most preferred metal element is that the colloidal silica of Si is as small inorganic filler.The shape of small inorganic filler can be the grain shape arbitrarily of spherical, needle-like, tabular, flakey, broken shape etc. in addition, has no particular limits.

As the lower limit of the average grain diameter of small inorganic filler, preferred 5nm, preferred especially 10nm.On the other hand, as the upper limit of the average grain diameter of small inorganic filler, preferred 50nm, preferred especially 25nm.This be because: during less than above-mentioned scope, the surface of small inorganic filler can uprise, and is easy to generate cohesion etc. in the average grain diameter of small inorganic filler, otherwise, if average grain diameter surpasses above-mentioned scope, then gonorrhoea takes place in the influence because of the short wavelength, can not keep the transparency of optical sheet 1 fully.

As the lower limit of the use level (the only use level of inorganic matter composition) of 100 parts of the relative substrate polymers of small inorganic filler, divide in solid and to convert, preferred 5 parts, preferred especially 50 parts.On the other hand, as the upper limit of the above-mentioned use level of small inorganic filler, preferred 500 parts, more preferably 200 parts, preferred especially 100 parts.This be because: if the addition of small inorganic filler is less than above-mentioned scope, the hear resistance that then probably can not present optical sheet 1 fully, otherwise if use level surpasses above-mentioned scope, then probably the become light transmittance of difficulty, optical layers 3 of the cooperation in polymer composition reduces.

As above-mentioned small inorganic filler, can use the filler that is fixed with organic polymer in its surface.Like this by using the fixing small inorganic filler of organic polymer, seek in the binding agent 7 dispersiveness, with the raising of the compatibility of binding agent 7.For this organic polymer, have no particular limits about having or not of its molecular weight, shape, composition, functional group etc., can use organic polymer arbitrarily.In addition for the shape of organic polymer, can use the straight chain shape, divide the organic polymer of the arbitrary shape of dendritic, cross-linked structure etc.

As the concrete resin that constitutes above-mentioned organic polymer, can enumerate for example polyolefin of (methyl) acrylic resin, polystyrene, polyvinyl acetate, polyethylene, polypropylene etc., the polyester of polyvinyl chloride, polyvinylidene chloride, PETG etc. and their copolymer, by the functional group of amino, epoxy radicals, hydroxyl, carboxyl etc. partial modification resin etc.Wherein, the organic polymer that contains (methyl) acrylic compounds unit of (methyl) acrylic resin, (methyl) acrylic acid (ester)-phenylethylene resin series, (methyl) acrylic acid (ester)-polyester based resin etc. is had tunicle as material that must composition form ability, preferably.On the other hand, preferably have the resin with the substrate polymer compatibility of above-mentioned polymer composition, therefore, the resin of most preferably identical composition with the substrate polymer that contains in the polymer composition.

What illustrated is that small inorganic filler also can include organic polymer in particulate.Like this, can be to give the pliability and the toughness of appropriateness as the inorganic matter of the nuclear of small inorganic filler.

Above-mentioned organic polymer can use the polymer that contains alkoxyl, and the every 1g of small inorganic filler that preferably is fixed with organic polymer as its content is 0.01mmol～50mmol.By this alkoxyl, can make with the compatibility that constitutes the matrix resin of binding agent 7, the dispersiveness in binding agent 7 and improve.

Above-mentioned alkoxyl is represented the RO base with the metallic element bonding that forms the particulate skeleton, and this R is for also can substituted alkyl, the RO base in the particulate can be identical also can difference.As the concrete example of R, can enumerate methyl, ethyl, n-pro-pyl, isopropyl, normal-butyl etc.The preferred use and the identical metal alkoxide of metal that constitutes small inorganic filler.At small inorganic filler is under the situation of colloidal silica, preferably uses the alkoxyl of silicon as metal.

Containing ratio for the organic polymer in the small inorganic filler that is fixed with organic polymer has no particular limits, and is that benchmark is 0.5 quality %～50 quality % with small inorganic filler preferably.

As the above-mentioned organic polymer that is fixed in the small inorganic filler, use has the polymer of hydroxyl, in constituting the polymer composition of binding agent 7, can contain at least a kind that is selected from polyfunctional isocyanate's compound, melamine compound and the amino resin that has more than 2 with the functional group of hydroxyl reaction.Thus, the matrix resin of small inorganic filler and binding agent 7 is by cross-linked structure and bonding, and storage stability, stain resistance, flexible, weatherability, storage stability etc. become good, and the tunicle that obtains has gloss.

As above-mentioned substrate polymer, preferably has the polyalcohol of cycloalkyl.Like this, import cycloalkyl in the polyalcohol as the substrate polymer that constitutes binding agent 7, the hydrophobicity of the water repellency of binding agent 7, resistance to water etc. improves thus, and the resistance to bend(ing) of the optical sheet 1 under the hot and humid condition, dimensional stability etc. improve.In addition, the key property of filming of the weatherability of optical layers 3, hardness, the richness of filming, solvent resistance etc. improves.In addition, compatibility and the uniformly dispersed of small inorganic filler with the small inorganic filler that is fixed with organic polymer on the surface becomes better.

As above-mentioned cycloalkyl, have no particular limits, can enumerate for example cyclobutyl, cyclopenta, cyclohexyl, suberyl, ring octyl group, ring nonyl, ring decyl, ring undecyl, cyclo-dodecyl, ring tridecyl, ring myristyl, cyclopentadecane base, ring cetyl, ring heptadecyl, ring octadecyl etc.

Polyalcohol with above-mentioned cycloalkyl obtains by the polymerism unsaturated monomer copolymerization that will have cycloalkyl.Polymerism unsaturated monomer with this cycloalkyl is meant the polymerism unsaturated monomer that has at least 1 cycloalkyl in molecule.As this polymerism unsaturated monomer, have no particular limits, for example can enumerate (methyl) cyclohexyl acrylate, (methyl) acrylic acid methyl cyclohexane ester, (methyl) acrylic acid tert-butyl group cyclohexyl, (methyl) acrylic acid cyclo-dodecyl ester etc.

In addition, can in polymer composition, contain isocyanates as curing agent.By contain isocyanate curing agent in polymer composition, form further firm cross-linked structure like this, the tunicle rerum natura of optical layers 3 further improves.As this isocyanates, can use and the same material of above-mentioned polyfunctional isocyanate's compound.Wherein, preferably prevent the fatty family isocyanates of its colour changed into yellow of tunicle.

Particularly using under the situation of polyalcohol as substrate polymer, as the curing agent that in polymer composition, cooperates, any mixing more than a kind or 2 kinds in hexamethylene diisocyanate, IPDI and the XDI can be used.If use these curing agent, because the curing reaction speed of polymer composition increases, even therefore use the cation of the dispersion stabilization that helps small inorganic filler be material as antistatic agent, also compensating cation is the reduction of the curing reaction speed that causes of antistatic agent fully.In addition, the raising of the curing reaction speed of this polymer composition helps small inorganic filler uniformly dispersed in binding agent.Its result, optical sheet 1 can further suppress bending, the flavescence that heat, ultraviolet ray etc. cause.

And, can be in polymer composition mixing antistatic agent.Polymer composition by mixing antistatic agent forms binding agent 7 like this, presents anti-static effect thus in optical sheet 1, can prevent to attract dust or with the charged rough sledding that produces that overlaps the difficulty that becomes etc. of prismatic lens etc. because of static.If in addition antistatic agent is coated the surface, then produce being clamminess of surface, dirt, but like this by mixing in polymer composition, this drawback reduces.As this antistatic agent, there is no particular limitation, for example can using, the anion of alkyl sulfate, alkylphosphonic etc. is an antistatic agent, the cation of tertiary amine salt, imidazolinium compounds etc. is an antistatic agent, the nonionic of polyethylene glycol system, polyoxyethylene sorbitan monostearate, glycollyl amine etc. is an antistatic agent, the macromolecular antistatic agent of polyacrylic acid etc. etc.Wherein, the preferred bigger cation of anti-static effect is an antistatic agent, realizes anti-static effect with a spot of interpolation.

Also easy adhesive linkage (bottom) (not shown) can be set between substrate layer 2 and optical layers 3.The not special restriction of average thickness being provided with under the situation of easy adhesive linkage for example can be about 1 μ m～30 μ m.By so easy adhesive linkage is set, as making via the substrate layer 2 of easy adhesive linkage and the reliable structure of joint of optical layers 3, obtaining more stable stepped construction becomes possibility.Resin as constituting easy adhesive linkage preferably uses acrylic resin, polyurethane series resin, polyester based resin, and rubber is resin etc.

As the example of the acrylic resin that constitutes easy adhesive linkage, can enumerate acrylic acid, methacrylic acid, the derivative that reaches with them is the resin of composition.Specifically, can enumerate acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, butyl acrylate, acrylic acid-2-ethyl caproite, acrylamide, acrylonitrile, hydroxy acrylate etc. with can with the copolymer of the monomer (for example styrene, divinylbenzene etc.) of their copolymerization.

Constitute the polyurethane series resin of easy adhesive linkage, for have the resin of amino-formate bond on main chain, the reaction by polyisocyanates and polyalcohol obtains usually.As the example of polyisocyanates, can enumerate TDI, MDI, NDI, TODI, HDI, IPDI etc.In addition, as the example of polyalcohol, can enumerate ethylene glycol, propane diols, glycerine, hexanetriol etc.In addition, also can use resin by making chain elongation agent and the polyether polyols with reduced unsaturation reaction that obtains by polyisocyanates and polyalcohol that molecular weight has been increased.

As the polyester based resin that constitutes easy adhesive linkage, for have the resin of ester bond on main chain, the reaction by polycarboxylic acid and polyalcohol obtains usually.As polycarboxylic example, can enumerate fumaric acid, itaconic acid, adipic acid, decanedioic acid, terephthalic acid (TPA), M-phthalic acid.As the example of polyalcohol, can enumerate above-mentioned about polyurethane series resin and illustrative resin.

The rubber that constitutes easy adhesive linkage is that the typical example of resin is the diene series synthetic rubber.As the elastomeric example of diene series, can enumerate copolymer, styrene-butadiene-acrylonitrile copolymer, its polymers of styrene-butadiene-divinylbenzene, hycar, polychlorostyrene dibutene of polybutadiene, styrene-butadiene etc.

As shown in Figure 2, the full run-down type liquid crystal display optical sheet 1 of Fig. 1 can form operation (STP1), stretching process (STP2) and optical layers formation operation (STP3) by base material film and make.

Base material film in the manufacture method of the optical sheet 1 of Fig. 2 forms operation (STP1), be following operation: by using the well-known extrusion moulding of T die head, as shown in Figure 3, forming the bar-shape body that is made of the polyester based resin 4 that contains filler 5 substantially equably is base material film squeeze-up 9.As the well-known extrusion moulding that uses the T die head, can enumerate for example felt wrapped roll method, chill roll method.

The extrusion molding apparatus that base material film forms the part of operation (STP1) by occupying schematic diagram shown in Figure 4 obtains implementing.This extrusion molding apparatus mainly possesses extruder and T die head 20, a pair of compression roller 21, coiling machine etc.Can use single shaft extruder or biaxial extruder as extruder.As T die head 20, can use the well-known type of for example burnt tail shape die head, branch pipe die head, hanger-style die etc.A pair of compression roller 21 is in abutting connection with parallel the setting in ground, and extruder and T die head 20 are that sheet ground constitutes can be in the roll gap (nip) of a pair of compression roller 21 mixture 8 of the polyester based resin 4 of molten condition and filler 5 be extruded.This a pair of compression roller 21 is provided with the temperature control device, surface temperature control can be constituted on the temperature ground that is suitable for extrusion molding most.As compression roller 21, the preferred metallic elastic roller that comprises metallic roll and covered elastomeric flexible roller from the teeth outwards that uses.Use the extrusion molding apparatus of this structure, at first the polyester based resin 4 of molten condition and the mixture 8 of filler 5 are supplied with T die head 20, extrude this mixture 8 by extruder and T die head 20, push, form base material film squeeze-up 9 thus with a pair of compression roller 21.What illustrated is, the melt temperature of the polyester based resin of extruding from T die head 20 4 is considered the fusing point etc. of employed polyester based resin and suitably selected.

In the polyester based resin 4 that constitutes base material film squeeze-up 9, filler 5 disperses substantially equably, and still, for the surface of base material film squeeze-up 9, polyester based resin 4, filler 5 are outstanding hardly, form the face of substantially flat.There is no particular limitation for the thickness of base material film squeeze-up 9, but recently suitably set according to the structure of employed T die head, the stretching carried out afterwards, can be about 40 μ m～2000 μ m.

Stretching process in the manufacture method of optical sheet 1 (STP2) is following operation: as shown in Figure 3, to form the base material film squeeze-up 9 that forms in the operation at above-mentioned base material film and stretch, and form as stretched film thus, be the substrate layer 2 of biaxially oriented polyester film in film length direction and film width.

This stretching process (STP2) can carry out under the softening temperature of the polyester based resin 4 that constitutes base material film squeeze-up 9 and the temperature that is fit between the melt temperature.Draw ratio in the stretching process can be adjusted according to the thickness of desired substrate layer 2 (biaxially oriented polyester film), but the stretching ratio of preferred length direction is 2.5 times～4.5 times, and the stretching ratio of width is 3 times～5 times.The thickness of the substrate layer 2 that has stretched is compared this draw ratio (amassing) with the thickness of base material film squeeze-up 9 the value of inverse is also thin.The preferred thickness of substrate layer 2 as mentioned above.The stretching ratio of the length direction by making biaxially oriented polyester film is more than 2.5 times and the stretching ratio of width is more than 3 times, and the filler 5 that contains in the inside of base material film squeeze-up 9 follows the place of the majority on polyester based resin 4 face at substrate layer that exists around it outstanding.And the protuberance of the majority that is formed by filler 5 etc. disperses other the surface of layer on some ground and the rear side that is laminated in optical sheet to contact, and prevents the adhesion of substrate layer and other layer thus effectively.In addition, the stretching ratio of the length direction by making biaxially oriented polyester film is below 4.5 times and the stretching ratio of width is below 5 times, by filler 5 and the ledge of the polyester based resin 4 that exists on every side, obtain the adhesion function that prevents of height, the while can prevent the reduction of the mechanical strength that the excessive filming outstanding, film of the surplus of filler 5 grades causes.

The biaxial stretch-formed device 22 of the well-known structure of stretching process (STP2) by having a part that occupies schematic diagram shown in Figure 4 is implemented.This biaxial stretch-formed device 22 mainly possesses heating extension section, heat treatment portion etc.Can adopt the well-known method of using the biaxial stretch-formed method of periosteum, the biaxial stretch-formed method of flat film etc. as biaxial stretch-formed method.In addition, biaxial stretch-formed method can be also that stretching with the stretching of film length direction and film width separates and the biaxial stretch-formed one by one method of carrying out, biaxial stretch-formed method when also can be the stretching of the stretching of carrying out the film length direction simultaneously and film width.According to biaxial stretch-formed method one by one, can obtain the stretched film that flatness and dimensional stability are good, uneven thickness is few.On the other hand, according to biaxial stretch-formed method of while, can obtain the good stretched film of in-plane equilibrium.

As biaxial stretch-formed one by one method, for example, the warmed-up roller group of base material film squeeze-up 9 guiding can be stretched in the film length direction, then control the two ends of this film, the stenter that has been heated of guiding on one side with anchor clamps on one side, stretch at the film width.As the method for biaxial stretch-formed method of while, for example, with anchor clamps control the two ends of base material film squeeze-up 9 on one side, the stenter that on one side its guiding has been heated stretches at the film width, meanwhile, by accelerating the anchor clamps speed of travel, can carry out the stretching of film length direction.Generally speaking, for these stretching things, in order to give plane stability, dimensional stability and heat-treat.

It is following operation that optical layers in the manufacture method of the optical sheet 1 of Fig. 2 forms operation (STP3): as shown in Figure 3, be that the biaxially oriented polyester film that forms in the above-mentioned stretching process is on the surface of substrate layer 2, use well-known roller coating technology, stacked contain a plurality of light diffusing agent 6, with the optical layers of the binding agent 7 of this light diffusing agent 6 with composition 10, then carry out drying, form optical layers 3 thus, finish optical sheet 1.

The roll coater of the well-known structure of the roller coat of stacked step (STP3) by having a part that occupies schematic diagram shown in Figure 4 is implemented.This roll coater mainly possesses coating tray 23, pick-up roll 24a, adjusts roller 24b, applicator roll 24c and backing roll 24d.Can use the direction of rotation of applicator roll and identical direct roller coating machine or the direction of rotation of applicator roll and the opposite reverse coater of direct of travel of coated article of direct of travel of coated article.The optical layers that coating tray 23 usefulness contain the binding agent 7 of a plurality of light diffusing agent 6 and this light diffusing agent 6 fills with composition 10, by the rotation of pick-up roll 24a, from coating tray 23 optical layers is accepted with composition 10.The optical layers that contains light diffusing agent 6 and binding agent 7 like this is attached to the outer peripheral face of pick-up roll 24a with component 10, is handed off to applicator roll 24c.During this time, adjust roller 24b and adjust the amount of the optical layers of the outer peripheral face that is attached to pick-up roll 24a with composition 10.Be attached with the applicator roll 24c of optical layers with composition 10, by direction identical or rightabout rotation with the transport direction of substrate layer 2, propping up the substrate layer 2 upper strata laminated optical layers compositions 10 that are held between applicator roll 24c and the backing roll 24d, then carry out drying, form optical sheet 1 as the duplexer of substrate layer 2 and optical layers 3.

The optical layers that optical layers forms in the operation (STP3) is used the stacked of composition 10, also can replace using the method for above-mentioned roll coater, adopt the well-known coating process that uses rod to be coated with machine, doctor knife coater, spin coater, gravure coating machine, flow coater, flush coater, serigraphy etc.

Also can form operation (STP3) before in optical layers at stretching process (STP2) afterwards, the operation that forms above-mentioned easy adhesive linkage (bottom) is set on the surface of substrate layer 2.Method and device as under the situation that forms easy adhesive linkage can use the method and apparatus identical with the formation of optical layers 2.Also can be in being used to form the coating fluid of easy adhesive linkage, resinous principle 100 mass parts cooperate for example curing agent of the amount about 1 mass parts～5 mass parts (for example, polyisocyanates is that resin, carbodiimides are resin etc.) relatively.

Can form between the operation (STP3) in stretching process (STP2) and optical layers, or form operation (STP3) afterwards, carry out with given size the substrate layer 2 that obtains or the cutting operation of optical sheet 1 cutting in optical layers.After forming operation (STP3), carry out cutter's preface, can make desired optical sheet expeditiously in optical layers, can suppress that batching of optical sheet cause curl, the generation of peeling off etc. of optical layers.

Up to the present as above illustratedly, full run-down type liquid crystal display optical sheet according to present embodiment, the particle of filler is outstanding on the face of substrate layer with the polyester based resin that exists around it, form most ledges, realize effectively for preventing to adhere to (tightly being adhered together) function at other stacked layer of the rear side of substrate layer.In addition, according to this optical sheet, can balance reach well height prevent adhesion function, as the keeping of the desired transparency of optical sheet, and the maintenance of high mechanical strength.And then, owing to do not need to form in addition the operation that prevents adhesion layer, therefore can reach the reduction of the manufacturing cost that employed optical sheet is relevant in the full run-down type liquid crystal indicator with king-sized display area, the efficient activity of manufacturing process for optical sheet.In addition, as Fig. 2～shown in Figure 4, make the full run-down type liquid crystal display optical sheet with a continuous production line, the simplification of manufacturing process and high speed become possibility thus.

The full run-down type liquid crystal display optical sheet 11 of Fig. 5 is the related optical sheet of the embodiment different with Fig. 1, forms on its surface to have refrangible fine concaveconvex shape 12.In this optical sheet 11, the part with fine concaveconvex shape 12 plays a role as optical layers.The composition of the substrate layer 2 of optical sheet 11 constitutes, and is same with the optical sheet 1 of above-mentioned embodiment.

As long as the light diffusing of optical layers 3 equal extent in 12 realizations of fine concaveconvex shape and the above-mentioned embodiment, just have no particular limits, for example, can make the average out to 0.05 μ m～1 μ m of the height (apart from the height of the higher position, the end of two recesses of adjacency) of each protuberance.

Manufacture method as optical sheet 11 has no particular limits, and for example can use following method.Promptly, can be set forth in above-mentioned stretching process (film length direction and film width biaxial stretch-formed one by one or simultaneously biaxial stretch-formed) before, (a) be implemented in the sheet mould of counter-rotating shape on surface, the mixture of stacked polyester based resin and filler, peel off the method for the operation of this sheet mould with optical sheet; (b) be implemented in the method for the injection moulding operation of the molten mixture that injects injection polyester based resin and filler in the mould of counter-rotating shape on surface with optical sheet; (c) implement mixture to the polyester based resin that forms sheet and filler heat once more, and above-mentioned same mould and metallic plate between, exert pressure the method for the operation of transfer printing shape; (d) in the roll gap with the roller die of the counter-rotating shape on the molten mixture of polyester based resin and the filler surface by having optical sheet at side face and other roller, the method for the operation of the above-mentioned shape of transfer printing.

Full run-down type liquid crystal display optical sheet according to present embodiment, same with the optical sheet of above-mentioned embodiment, by the particle of filler and the ledge of the polyester based resin that exists on every side, realize the adhesion function that prevents of substrate layer and other layer effectively, can keep the high transparency and mechanical strength simultaneously.And then, owing to do not need to form in addition the operation that prevents adhesion layer, therefore can reach the reduction of manufacturing cost, the efficient activity of manufacturing process etc. for optical sheet.In addition, by possessing the optical sheet of optical layers, can seek the raising of light diffusing, the facilitation of control with so fine concaveconvex shape.

Full run-down type liquid crystal display optical sheet of the present invention is not limited to these embodiments.For example, also can have the optical layers of fine concaveconvex shape other formation the in the surface of substrate layer.Material as the optical layers of the fine concaveconvex shape of having of so other formation can use to have the radioparent synthetic resin of light.As such synthetic resin, can enumerate for example polyester based resin of PETG, PEN etc.; The cellulose-based resin of biacetyl cellulose, triacetyl cellulose etc.; Polycarbonate-based resin; The acrylic resin of polymethyl methacrylate etc.; The phenylethylene resin series of polystyrene, acrylonitrile styrene copolymer etc.; The olefin-based resin of polyethylene, polypropylene, polyolefin, ethylene propylene copolymer etc. with ring-type or norbornane structure; Vinyl chloride-based resin; The acid amides of nylon, aromatic polyamide etc. is a resin; Imines is a resin; Sulfone is a resin; Polyether sulfone is a resin; Polyether-ether-ketone is a resin; Polyphenylene sulfide is a resin; The ethenol system resin; The vinylidene chloride resin; Vinyl butyral (PVC ニ Le Block チラ one Le) is a resin; The acrylic ester resin; Polyformaldehyde is a resin; Epoxy is a resin etc.

In addition, as surperficial stacked optical layers, except above-mentioned, also for example can use (i) to have the micro-lens sheet that comprises a plurality of hemispheric lenticular microlens arrays on the surface at substrate layer; The prismatic lens that (ii) has the prism portion of a plurality of triangle columns with ribbon on the surface; Lenticular lens (the レ Application チキユラ one レ Application ズ) sheet that (iii) has a plurality of half-terete cylindrical lenses with ribbon on the surface; The (iv) Fresnel lens of only arranging from the teeth outwards etc. according to the curvature of lens.For these optical layers, also can on substrate layer, carry out stacked according to well-known coating process.

The manufacture method of full run-down type liquid crystal display optical sheet is not limited to utilize 1 continuous process line method.Also can consider the sharing etc. of flexibility, manufacturing installation, human resources of production process, with base material film form operation, stretching process, and optical layers form operation and implement as separately production line.

Full run-down type liquid crystal display optical sheet of the present invention, in the back light unit that the liquid crystal indicator of televimonitor etc. is used, not only as near the following diffusion sheet of setting backlight but also as other the last diffusion sheet use of top of optical sheet that is arranged at prismatic lens etc.That is, because full run-down type liquid crystal display optical sheet of the present invention has the excellent adhesion function that prevents, therefore preferred conduct is arranged near the following diffusion sheet on the even surface backlight to be used.And, owing to such prevent that adhesion function from not hindering and be applicable to down diffusion sheet purposes in addition, therefore this full run-down type liquid crystal display optical sheet is not only used as diffusion sheet down but also as last diffusion sheet, can keep the transparency of excellence and mechanical strength thus, seek the efficient activity of manufacturing efficient of back light unit integral body and the reduction of manufacturing cost simultaneously.

Embodiment

Below be described in detail the present invention based on embodiment, cut the not explanation of being defined property of the present invention based on the note of present embodiment.

(1) prevents adhesiveness

Being situated between on each polyester film is overlapped with the acrylic compounds plate fully by water, with its under the environmental test condition (70 ℃ * RH95%) placed 24 hours down.After the placement, attempt peeling off of polyester film and acrylic compounds plate, the easiness of peeling off is judged based on following benchmark.

Extremely easily peeled off ... ◎ (extremely good)

Peeled off ground easily ... zero (well)

Resistance is arranged a little, but peeled off ... △ (bad slightly)

Resistance is big, is not easy to peel off ... * (bad)

(2) confficient of static friction and the coefficient of kinetic friction

For each polyester film, use sliding test machine (slip tester), measure the confficient of static friction and the coefficient of kinetic friction according to the ASTM-D1894-08 specification.

(3) arithmetic average roughness (Ra)

For each polyester film, obtain arithmetic average roughness (Ra) based on JIS B0601-2001.

(4) maximal roughness (Ry)

For each polyester film, obtain maximal roughness (Ry) based on JIS B0601-2001.

(5) ten mean roughness (Rz)

For each polyester film, obtain 10 mean roughness (Rz) based on JIS B0601-2001.

(6) full light transmittance

For the optical sheet that is laminated with optical layers, based on JIS K7105-1981, by the full light transmittance of the triumphant mensuration of mist degree analyzer by スガ testing machine Co., Ltd. system.

(embodiment 1)

The molten mixture of the colloidal silica 0.1 quality % of PETG (hereinafter referred to as " PET ") 99.9 quality %, average grain diameter 120nm is supplied with the T die head, carry out extrusion molding, form PET film squeeze-up, this PET film squeeze-up with in 3 times in film length direction, stretch one by one with the multiplying power 4 times of film widths, is obtained the substrate layer that average thickness is 188 μ m (biaxially oriented polyester film) thus.For this biaxially oriented polyester film, prevent adhesiveness, confficient of static friction, the coefficient of kinetic friction, arithmetic average roughness (Ra), maximal roughness (Ry) and 10 mean roughness (Rz) according to said method mensuration.And then, on the surface of this biaxially oriented polyester film, coating contains the conjugate solutions of polyurethane series resin (" the バイロ Application 3900 " of Japan's weaving (strain)) 100 mass parts and modified polyisocyanate (" the コロネ-ト L " of Japanese polyurethane industry (strain)) 5 mass parts, make its drying, form the easy adhesive linkage (bottom) of thickness 10 μ m thus.Then, at " PUVA-1033 " of colloidal silica 50 mass parts, curing agent (Japanese polyurethane industry (strain) " コロネ-ト HX ") 5 mass parts and light stabilizer (Da mound chemistry (strain) that contains with the PEPA resin glue complex " the バイロ Application 200 " of (Japan weaving (strain)) 100 mass parts, the average grain diameter 20nm that are substrate polymer) in the polymer composition of 5 mass parts, 50 parts of the acrylic resin beads (ponding changes into " MBX-15 " of product industry (strain)) of mixing average grain diameter 15 μ m are made coating liquid.This coating liquid is coated on the surface of above-mentioned easy adhesive linkage, it is solidified, form the optical layers of thickness 20 μ m thus, obtain optical sheet.For this optical sheet, measure full light transmittance according to said method.The measurement result of their rerum natura is listed in table 1.

(embodiment 2)

Except the average grain diameter of the colloidal silica that will use as the material composition that is used to form PET film squeeze-up became 80nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(embodiment 3)

Except the average grain diameter of the colloidal silica that will use as the material composition that is used to form PET film squeeze-up became 170nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(embodiment 4)

Except the quantitative change of the colloidal silica that will use as the material composition that is used to form PET film squeeze-up was 0.005 quality %, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in the table 1.

(embodiment 5)

Except the quantitative change of the colloidal silica that will use as the material composition that is used to form PET film squeeze-up was 2.0 quality %, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(comparative example 1)

Obtain the polyester film of average thickness 188 μ m except the stretching of not carrying out film length direction and film width, used as the substrate layer, all the other form substrate layer and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(comparative example 2)

Except the average grain diameter of the colloidal silica that will use as the material composition that is used to form PET film squeeze-up became 40nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(comparative example 3)

Except the average grain diameter of the colloidal silica that will use as the material composition that is used to form PET film squeeze-up became 300nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(embodiment 6)

Except the molten mixture of polymethyl methacrylate (hereinafter referred to as " PMMA ") the particle 0.1 quality % that uses PETG 99.9 quality %, average grain diameter 120nm as the raw material that is used for PET film squeeze-up, all the other similarly to Example 1, form substrate layer (biaxially oriented polyester film) and optical sheet, measure above-mentioned various rerum natura.Measurement result one is listed in table 1.

(embodiment 7)

Except the average grain diameter of the PMMA particle that will use as the material composition that is used to form PET film squeeze-up became 80nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 6, measure each above-mentioned rerum natura.Its measurement result one is listed in table 1.

(embodiment 8)

Except the average grain diameter of the PMMA particle that will use as the material composition that is used to form PET film squeeze-up became 170nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 6, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(embodiment 9)

Except the quantitative change of the PMMA particle that will use as the material composition that is used to form PET film squeeze-up was 0.005 quality %, all the other were identical with embodiment 6, form substrate layer (biaxially oriented polyester film) and optical sheet, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(embodiment 10)

Except the quantitative change of the PMMA particle that will use as the material composition that is used to form PET film squeeze-up was 2.0 quality %, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 6, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(comparative example 4)

Obtain the polyester film of average thickness 188 μ m except the stretching of not carrying out film length direction and film width, used as the substrate layer, all the other form substrate layer and optical sheet similarly to Example 6, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(comparative example 5)

Except the average grain diameter of the PMMA particle that will use as the material composition that is used to form PET film squeeze-up became 40nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

(comparative example 6)

Except the average grain diameter of the PMMA particle that will use as the material composition that is used to form PET film squeeze-up became 300nm, all the other formed substrate layer (biaxially oriented polyester film) and optical sheet similarly to Example 1, measure each above-mentioned rerum natura.Measurement result one is listed in table 1.

[table 1]

Annotate 1, annotate 2: in these comparative examples, though prevent good adhesion, by electron microscope observation the time, the result observes fine damage on the surface of the acrylic compounds plate that is used to test.

Known to the result of table 1, the value that contains average grain diameter is the biaxially oriented polyester film of the embodiment 1～10 of interior inorganic filler of the scope of 70nm～200nm or organic filler, with do not carry out the polyester film of biaxial stretch-formed comparative example 1 and 4 and contain the comparative example 2 of filler of value and 5 biaxially oriented polyester film is compared with above-mentioned extraneous average grain diameter, present the adhesiveness that prevents of remarkable excellence.In addition, comparative example 3 and 6 polyester film by the big particle diameter of filler, demonstrate the high adhesiveness that prevents, but by electron microscope observation the time, the Local observations of the majority on the surface of stacked in test acrylic compounds plate is to fine damage.

And then as can be known, use the embodiment 1 and 6 of the value of average grain diameter as inorganic filler in the scope of the 120nm of 100nm～150nm or organic filler, with the embodiment 2 of the filler that contains value with this extraneous average grain diameter and 3 or

embodiment

7 and 8 compare, bring into play the better adhesiving effect that prevents.In addition we know, use amount is the inorganic filler of 0.1 interior quality % of the scope of 0.01 quality %～1 quality % or the embodiment 1 and 6 of organic filler, with the embodiment 4 of the filler that contains this extraneous amount and 5 or

embodiment

9 and 10 compare, same as described above, demonstrate the better adhesiving effect that prevents.

Utilizability on the industry

Directly play the type liquid crystal display optical sheet according to this, can effectively prevent from becoming possibility with the adhesion of other layer that is laminated in rear side, the simultaneously reduction of manufacturing cost and the efficient activity of manufacturing operation. Therefore, particularly for the large-area optical sheet of the big picture that is used for straight lower type liquid crystal display device, owing to can realize the significantly reduction of manufacturing cost and the simplification of making operation, therefore industrial is useful.

Claims

1. full run-down type liquid crystal display optical sheet, its be possess transparent substrate layer, at the full run-down type liquid crystal indicator of the stacked optical layers of the face side of this substrate layer, it is characterized in that,

The average grain diameter of this filler is 70nm～200nm.

2. full run-down type liquid crystal display optical sheet according to claim 1, wherein, the content of above-mentioned filler is 0.01 quality %～1 quality %.

3. full run-down type liquid crystal display optical sheet according to claim 1, wherein, above-mentioned filler is selected from silica, aluminium oxide, titanium dioxide, calcium carbonate, kaolin, barium sulfate, acrylic resin, melmac, organic siliconresin and crosslinked polystyrene.

4. full run-down type liquid crystal display optical sheet according to claim 1, wherein, the stretching ratio of the length direction of above-mentioned biaxially oriented polyester film is 2.5 times～4.5 times, the stretching ratio of width is 3 times～5 times.

5. full run-down type liquid crystal display optical sheet according to claim 1, wherein, the F5 value of the length direction of above-mentioned biaxially oriented polyester film and width is 80MPa～120MPa.

6. full run-down type liquid crystal display optical sheet according to claim 1, wherein, the confficient of static friction of above-mentioned biaxially oriented polyester film is 0.3～0.6, the coefficient of kinetic friction is 0.3～0.5.

7. full run-down type liquid crystal display optical sheet according to claim 1, wherein, the arithmetic average roughness of above-mentioned biaxially oriented polyester film (Ra) is 0.04 μ m～0.25 μ m.

8. full run-down type liquid crystal display optical sheet according to claim 1, wherein, the maximal roughness of above-mentioned biaxially oriented polyester film (Ry) is 0.4 μ m～0.8 μ m.

9. full run-down type liquid crystal display optical sheet according to claim 1, wherein, 10 mean roughness (Rz) of above-mentioned biaxially oriented polyester film are 0.3 μ m～0.6 μ m.

10. full run-down type liquid crystal display optical sheet according to claim 1, wherein, above-mentioned optical layers has light diffusing agent and its binding agent.

11. full run-down type liquid crystal display optical sheet according to claim 1, wherein, above-mentioned optical layers has fine concaveconvex shape, and described fine concaveconvex shape has refractiveness.

12. the back light unit that the full run-down type liquid crystal indicator is used, it is the back light unit that the full run-down type liquid crystal indicator that makes the light that sends from lamp disperse to import face side is used, it is characterized in that,

It possesses the described full run-down type liquid crystal display optical sheet of claim 1.