CN100460953C - High brightness light-diffusion sheet for back-light unit of liquid crystal display and method for manufacturing thereof - Google Patents

High brightness light-diffusion sheet for back-light unit of liquid crystal display and method for manufacturing thereof Download PDF

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CN100460953C
CN100460953C CNB2006101608359A CN200610160835A CN100460953C CN 100460953 C CN100460953 C CN 100460953C CN B2006101608359 A CNB2006101608359 A CN B2006101608359A CN 200610160835 A CN200610160835 A CN 200610160835A CN 100460953 C CN100460953 C CN 100460953C
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light
light diffusing
diffusing board
adhesive resin
diffusion particles
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CN101071222A (en
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金光源
李洪秀
李振雨
宋志善
崔容準
边京我
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Bao Xin new material (Suzhou) Co., Ltd.
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SANGBO CORP
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
    • G02B5/0226—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures having particles on the surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
    • G02B5/0231—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures the surface having microprismatic or micropyramidal shape
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
    • G02B5/0242—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of dispersed particles
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
    • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0051—Diffusing sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2300/00—Characterised by the use of unspecified polymers

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  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Nonlinear Science (AREA)
  • Dispersion Chemistry (AREA)
  • Materials Engineering (AREA)
  • Mathematical Physics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

Provided is a high-brightness light-diffusing panel used for the backlight unit of the liquid crystal display device and the making method. The high-brightness light-diffusing panel includes a cardinal plate, a light-diffusing layer and a back coating, the light-diffusing layer is formed at one surface of the cardinal plate and is made of one kind of compound, the compound includes light-diffusing granule, dissolvent and a first cementing agent colophony, the light-diffusing granule is provided with a specific gravity of 1.0 to 1.2 g/cm3 and a particle-size variation coefficient of no more than 15 percent, the particle-size variation coefficient is represented by the equation ''variation coefficient is equal to ( standard deviation is divided by mean value) is multiplied by 100'', the specific gravity of the dissolvent is 0.82 to 1.0 g/cm3 and the boiling point is 130 to 140 degree, and is used to regulate the rate of deposition of the light-diffusing granule, the difference value between the refractive index of the first cementing agent resin and the refractive index of the light-diffusing granule is no more than 0.01, the back coating is formed at the other surface of the cardinal plate, which includes tiny pearl whose friction coefficient is no more than 0.36(MIU) and the second cementing resin whose tensional modulus of elasticity is no more than 300MPa. The high-brightness light-diffusing panel increases the brightness, and reduces the scratch generated at the backing side of the light-diffusing panel and eliminates the adhesion.

Description

The light diffusing board of liquid crystal display backlight unit and manufacture method thereof
Technical field
The present invention relates to the high-luminance light diffusing panel and the manufacture method thereof of liquid crystal display backlight unit, more specifically relate to the high-luminance light diffusing panel and the manufacture method thereof that are used to prevent birefringence and adhesion and reduce the liquid crystal display backlight unit that scratches on it.
Background technology
Recently, LCD (LCD) has been used for the display of notebook, the large-sized monitor and the television indicator of desk-top computer gradually.Demand to the back light unit of the large scale that forms the LCD light source and high brightness increases.
Fig. 1 illustrates the example of the back light unit that has mainly adopted.As shown in Figure 1, back light unit comprises the light guide plate (LGP) 120 of use cathode fluorescent lamp (being specially cold-cathode fluorescence lamp (CCFL)) as light source 100.Back light unit also comprises light diffusing board 130 on the light-emitting area that is stacked on light guide plate 120 in the following sequence, prismatic lens 140 and 150 and screening glass 160.Reflecting plate 110 is stacked on the another side of the light guide plate opposite with light-emitting area 120.
The light diffusing board 130 of back light unit is used for diffused light, only launch by the light source 100 at a side surface that is positioned at light diffusing board 130 or the back side, light diffusing board is distributed in the whole surface and the refract light of screen, thereby light is converted to the even light in directive back light unit front.
Light diffusing board 130 comprises optical diffusion layer, substrate and back coating.The composition that forms optical diffusion layer comprises adhesive resin, rigidizer, antistatic agent, light diffusion particles and solvent.Collaborative optical transmission rate and the diffusion rate of improving of light diffusion particles and adhesive resin.For this light diffusion particles, can use various organic and inorganic particles.Using under the situation of organic granular as light diffusion particles, with an organic solvent, for example ethanol, acetone, methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), ethyl acetate or toluene.The proportion of this organic solvent and general light diffusion particles have very big-difference.For this reason, the dispersiveness of light diffusion particles in organic solvent reduces.In addition, precipitate in the stand-by period that light diffusion particles is comprised in manufacture process.Thus, described particle skewness in optical diffusion layer.In addition, above-mentioned solvent has low boiling.Therefore, being difficult to obtain levelability forms sediment.Thus, described particle skewness in optical diffusion layer.In addition, above-mentioned solvent has low boiling.Therefore, be difficult to obtain flow leveling, cause during the dry run that optical diffusion layer carries out after being coated with membrane process smooth.
The back coating of light diffusing board 130 is positioned at the position of direct contact lamp source, and it requires that the heat that light source produces is had stability.Therefore, back coating must have the skin hardness of superelevation.Therefore, scratch because the friction between back coating and the light guide plate 120 causes producing on back coating, friction is to be caused by the vibration that produces in the light guide plate modulated process that carries out in the position of adjacent back coating.
Summary of the invention
So, produced the present invention at the problems referred to above, the purpose of this invention is to provide a kind of high-luminance light diffusing panel that is used for liquid crystal display backlight unit, it prevents owing to birefringence reduces brightness, reduces the scuffing that produces and eliminate adhesion on the light diffusing board back side.
Another object of the present invention provides the method that a kind of manufacturing is used for the high-luminance light diffusing panel of liquid crystal display backlight unit, and this method increases brightness, reduces the scuffing that produces and eliminate adhesion on the light diffusing board back side.
According to an aspect of the present invention, can realize above-mentioned and other purpose by the high-luminance light diffusing panel that is provided for liquid crystal display backlight unit, described light diffusing board comprises:
Substrate;
Be formed on a lip-deep optical diffusion layer of substrate, wherein said optical diffusion layer is made by a kind of composition, and described composition comprises light diffusion particles, solvent and first adhesive resin, and described light diffusion particles has 1.0-1.2g/cm 3Proportion and be no more than 15% change in particle size coefficient, described change in particle size coefficient represents that by following formula described solvent has 0.82-1.0g/cm 3Proportion and 130-140 ℃ boiling point, be used for regulating the rate of deposition of light diffusion particles, the refractive index of described first adhesive resin and the refractive index difference of light diffusion particles are no more than 0.01,
[expression formula]
Variation factor=(standard deviation ÷ mean value) * 100; With
Be formed on another lip-deep back coating of substrate, wherein said back coating comprises that friction factor is no more than the microballon of 0.36 (MIU) and second adhesive resin that tensional modulus of elasticity is not more than 300MPa.
Solid matter content in the described composition can be 38-42%.
Described solvent can be the mixed solution that comprises butyl acetate and dimethylbenzene.
Described mixed solution can comprise the butyl acetate of dimethylbenzene/100 weight portions of 20-150 weight portion.
Described composition can comprise first adhesive resin of light diffusion particles/100 weight portions of 40-140 weight portion.
Described light diffusion particles can comprise two kinds of particles with different average-sizes.
Described solvent can have 0.86-1.0g/cm 3Proportion.
Described microballon can be made by nylon based or silicon base compound.
In addition, second adhesive resin can be the curable urethane acrylate resin of UV, described urethane acrylate resin can be three (2-acrylyl oxy-ethyl) isocyanates-2-acrylic acid, (1-methyl ethylidene) two (4, the inferior phenoxy group-2 of 1-, 1-ethylenedioxy-2,1-second two bases) terpolymer of ester and 1-hydroxyl-cyclohexyl-phenyl ketone.
According to another aspect of the present invention, the method of the high-luminance light diffusing panel that a kind of manufacturing is used for liquid crystal display backlight unit is provided, comprise preparation optical diffusion layer solution, described optical diffusion layer solution comprises light diffusion particles, solvent and first adhesive resin, described light diffusion particles has and is no more than 15% change in particle size coefficient, described change in particle size coefficient represents that by above expression formula the proportion of described solvent is 0.82-1.0g/cm 3Optical diffusion layer solution is coated on the surface of the substrate of making by polyethylene terephthalate (PET), and dry coated solution; With form back coating, described back coating comprises that friction factor is no more than the microballon of 0.36 (MIU) and at another lip-deep second adhesive resin of pet substrate.
In described preparation of compositions, light diffusion particles can comprise two kinds of particles with different average-sizes.
Description of drawings
According to detailed description below in conjunction with accompanying drawing, above and other objects of the present invention, character and other advantage will be more readily understood, wherein:
Fig. 1 is the schematic, exploded perspective view of traditional LCD back light unit;
Fig. 2 is the sectional view according to the light diffusing board of one embodiment of the invention;
Fig. 3 A is the figure of explanation according to the surface state of light diffusing board after friction test of comparing embodiment 1 manufacturing;
Fig. 3 B is the figure of explanation according to the surface state of light diffusing board after friction test of the embodiment of the invention 4 manufacturings;
Fig. 4 is the synoptic diagram of explanation according to the brightness measurement zone of the light diffusing board of another embodiment of the invention;
Fig. 5 is the figure of explanation according to the abrasion resistance test findings of the light diffusing board of the embodiment of the invention 4 and comparing embodiment 1 manufacturing; With
Fig. 6 is the decomposition diagram of liquid crystal display backlight unit, has applied the light diffusing board according to another embodiment of the invention thereon.
The Reference numeral table
100,600: light source 110,610: reflecting plate
120,620: light guide plate
130,630: light diffusing board
140,150; Prismatic lens 160: screening glass
200: optical diffusion layer 210: substrate
220: back coating
Embodiment
Describe the preferred embodiments of the invention in detail referring now to accompanying drawing.
Although for illustration purpose discloses the preferred embodiments of the invention, it should be appreciated by those skilled in the art that and to carry out various changes, interpolation and replacement.Scope and spirit of the present invention are not limited to described embodiment.In the accompanying drawings, for clearer explanation the present invention, amplified the size or the thickness in various films or zone.
Fig. 2 is the sectional view according to the light diffusing board of one embodiment of the invention.With reference to figure 2, light diffusing board of the present invention comprises substrate 210, be coated in substrate 210 upper surface optical diffusion layer 200 and be stacked on the back coating 220 of the lower surface of substrate 210.
Optical diffusion layer 200 is used for diffusion or refraction from the light of LCD back light unit, thus equably with light diffusion to whole screen surface.As mentioned above, optical diffusion layer 200 contains a kind of composition, comprises first adhesive resin, rigidizer, light diffusion particles, antistatic agent, spreading agent and solvent.
Thereby described solvent is dissolving first adhesive resin, rigidizer, light diffusion particles, antistatic agent and spreading agent makes their mixed uniformly materials.Particularly, described solvent should be given first adhesive resin and light diffusion particles with polymolecularity, makes light diffusion particles can be dispersed in first adhesive resin.In the manufacturing of high-luminance light diffusing panel according to the present invention, described solvent should prevent that also light diffusion particles from precipitating in first adhesive resin, thereby prevents that light diffusion particles from disperseing inhomogeneous in first adhesive resin.Therefore, described solvent can have 0.82-1.0g/cm 3Proportion.Preferably, described solvent has 0.86-1.0g/cm 3Proportion and 130-140 ℃ boiling point.
When the proportion of described solvent is lower than 0.82g/cm 3The time, the dispersiveness of light diffusion particles reduces, thereby light diffusion particles is deposited in the described solvent in described process.Therefore, described solution must stir once more.On the other hand, the proportion when described solvent is higher than 1.0g/cm 3The time, it is heavier than first adhesive resin that described solvent becomes, and therefore can be enriched in the below of first adhesive resin, thus dry back stain occurs on optical diffusion layer 200.The mixed solution that can use butyl acetate and dimethylbenzene is as solvent.Yet described solvent is not limited to this potpourri, but can use proportion to be 0.82-1.0g/cm 3Various materials as solvent.Preferably, the dimethylbenzene with the 20-150 weight portion mixes with the butyl acetate of 100 weight portions.When the amount of dimethylbenzene during less than 20 weight portions, the surface tension of mixed solution increases and stay droplet after coating.On the other hand, when the amount of dimethylbenzene during,, thereby can not carry out dry run reposefully because the boiling point of dimethylbenzene is high relatively greater than 150 weight portions.Residual dimethylbenzene also can produce stain.In addition, when the boiling point of described solvent was 130-140 ℃, the optical diffusion layer 200 that is coated on the substrate 210 showed good levelability after dry run.When the boiling point of described solvent during less than 130 ℃, described solvent may be evaporated before the optical diffusion layer 200 that is coated with guarantees the levelability of expectation.On the other hand, when the boiling point of described solvent during greater than 140 ℃, substrate 210 warpages also apply load to dry run, thus the production process loss.
According to the present invention, light diffusion particles has 1.0-1.2g/cm 3Proportion and be no more than 15% change in particle size coefficient.
Described light diffusion particles can comprise acryl particles; alkylene particle or organic granular; wherein said acryl particles is by methyl methacrylate; Jia Jibingxisuanyizhi; isobutyl methacrylate; n-BMA; the positive butyl ester of methacrylic acid methyl; acrylic acid; methacrylic acid; its multipolymer or its terpolymer are made; described alkylene particle is by tygon; polystyrene or polypropylene are made; described organic granular is multilayer and multi component particle for example, and it obtains by the multipolymer of formation acryloyl and alkylene or the layer monomer different with multipolymer or layer of homopolymer with coating of homopolymer pellets.Preferably, light diffusion particles is made by polymethylmethacrylate (PMMA).In addition, for light diffusion particles, can use to show particle slightly different with the refractive index of first adhesive resin or that equate.
Described variation factor is defined as expression formula " variation factor=(standard deviation ÷ mean value) * 100 ".Usually, standard deviation is through being commonly used to represent dispersion degree.In the present invention, use variation factor to substitute standard deviation with mean variation, described variation factor can be used for controlling the distribution of light diffusion particles and with the distribution applications controlled in required process, and do not consider mean value.Can see that from the above-mentioned definition of variation factor variation factor is approaching more zero, the deviation between the particle is more little.In the present invention, use variation factor to be no more than 15% light diffusion particles and maximize the light peptizaiton.That is to say, when the variation factor of light diffusion particles greater than 15% the time, since the wide particle diameter of light diffusion particles distribute cause light diffusion particles with multilayer but not the form of individual layer pile up, even the average-size that the coating thickness of optical diffusion layer 200 equals light diffusion particles in the initial application process of optical diffusion layer 200 also is like this.As a result, descending appears in the light diffusion effect.
Light diffusion particles can be two kinds of particles with different average-sizes.In this case, the particle with big average-size applies one deck on a surface of substrate 210, have the particles filled gap that is limited between the coated larger particles of less average-size.This structure has been improved the diffusion of light rate that incides substrate 210 back sides.
For example, when light diffusion particles comprised the particle of two kinds of different average-sizes of 20 μ m and 10 μ m, if the variation factor of two kinds of particles all is no more than 15%, then size distribution narrowed down.Therefore, in this case,, obtain uniform light orientation when the light that incides substrate 210 back sides during by diffusion.The result is the rectilinearity of the light that helps propagating forward.This is to make that the particle of average-size with 20 μ m is stacked with form of single sheet because the average particle size distribution of light diffusion particles is narrow, and the particle with average-size of 10 μ m fill up the gap between the stacked large-size particle.Therefore, realize improvement to the diffusion of light rate that incides substrate 210 back sides.
As mentioned above, for even distribution granule in the gap that between bulky grain, is limited, except regulating particle grain size distribution, be necessary to increase the solid matter content in the mixed solution.Preferably, the solid matter content in the mixed solution is 38-42%.When the solid matter content in the mixed solution less than 38% the time, the excess stickiness of mixed solution reduces.As a result, the optical diffusion layer 200 of coating is difficult to the thickness evenness that obtains expecting, therefore the brightness uniformity that obtains expecting that is difficult to.When the solid matter content in the mixed solution greater than 42% the time, the excess stickiness of composition increases.For this reason, after finishing coating procedure, may stay droplet, thereby produce stain.At this, solid matter content is meant the percentages of ingredients of other except solvent in the composition.
In addition, preferably, the proportion of light diffusion particles is 1.0-1.2g/cm 3This restriction is to consider with the relation of the proportion of used solvent and definite.When the proportion of light diffusion particles less than 1.0g/cm 3The time, its proportion can cause the diffusion rate of light diffusion particles in the solvent to reduce less than the proportion of solvent for use.In this case, also be difficult to control the thickness distribution of the optical diffusion layer 200 of coating.On the other hand, the proportion when light diffusion particles surpasses 1.2g/cm 3The time, the rate of deposition of light diffusion particles in solvent raises undesirably.As a result, in coating procedure, must constantly repeat to stir solvent, so the production process loss.
For rectilinearity that improves the light that shines the light diffusing board front and the brightness that improves light diffusing board thus, preferably the refractive index with light diffusion particles is adjusted to the refractive index that is similar to first adhesive resin.More preferably, the refringence between the light diffusion particles and first adhesive resin is no more than 0.01.When the refringence between the light diffusion particles and first adhesive resin was no more than 0.01, the brightness of the light that sends from the light diffusing board front increased.
The dry thickness of first adhesive resin is equivalent to the 50-75% of light diffusion particles average-size.When the dry thickness of first adhesive resin less than the light diffusion particles average-size 50% the time, first adhesive resin layer is difficult to firmly support optical diffusion layer.On the other hand, when the dry thickness of first adhesive resin surpass the light diffusion particles average-size 75% the time, the light diffusion effect reduces.
The light transmission of light diffusion particles and diffusion rate depend on the content of the light diffusion particles that comprises in first adhesive resin.In order to obtain high light transmission and diffusion rate, the content of the light diffusion particles that comprises in first adhesive resin is preferably first adhesive resin of 40-140 weight portion/100 weight portions.When the content of light diffusion particles during less than 40 weight portions, the light diffusion effect that is caused by light scattering reduces.On the other hand, when the content of light diffusion particles during greater than 140 weight portions, light transmission reduces.
Advantageously, first adhesive resin in the composition of optical diffusion layer 200 has the high adhesion force to substrate 210.In addition, first adhesive resin should have the compatibility with light diffusion particles.
Use acryl resin as first adhesive resin.Preferably, acryl resin has about 1.49 refractive index, makes the refractive index difference of winning between adhesive resin and the light diffusion particles be no more than 0.01.For example, under the situation that light diffusion particles is made by PMMA, light diffusion particles has identical refractive index with acryl resin, and promptly 1.49, the light straight line that incides light diffusing board from the LCD back light unit passes the whole surface of lcd screen, thereby improves brightness.
In order to increase the performance of first adhesive resin, for example thermotolerance, abrasion resistance and stickability can add rigidizer in the composition of optical diffusion layer 200.
The spreading agent that comprises in the composition of optical diffusion layer 200 plays the effect that kept the uniform state of composition before composition being coated on the substrate 210.Do not limit the kind of spreading agent.
Substrate 210 of the present invention is transparent support things.Substrate 210 is made by at least a material that is selected from following material: polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), Polyethylene Naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyene propyl ester (polyallylate), polyimide, polycarbonate (PC), Triafol T (TAC) and cellulose acetate propionate (CAP).Preferably, substrate 210 is made by PET.Substrate 210 must have and the tack of the first adhesive resin excellence, being no less than 90% transmissivity and not causing the uniform outer surface smoothness of luminance deviation the light that incides substrate 210 back sides.Preferably, the thickness of substrate 210 is 50-250 μ m.When the thickness of substrate 210 during less than 50 μ m, substrate 210 is difficult to handle in manufacture process.On the other hand, when the thickness of substrate 210 during greater than 250 μ m, substrate 210 has the structure that can not satisfy the nearest thin profile trend of LCD module.
Place the back coating 220 of the bottom surface of substrate 210 to comprise that friction factor is no more than the microballon of 0.36 (MIU) and second adhesive resin that tensional modulus of elasticity is no more than 300MPa.At this, MIU is by the mean value of the friction factor (no unit) of KES measurement, does not have unit.Because back coating 220 contacts are positioned at the element at the light diffusing board back side, for example therefore light guide plate in the process of regulating light guide plate, rubs between back coating 220 and light guide plate inevitably.This friction causes the scuffing on the light guide plate.Usually, light guide plate is made by acryl resin, and its friction factor is 0.37-0.38 (MIU).Therefore, the friction factor microballon that is no more than 0.36 (MIU) prevents the scuffing on light guide plate.Described microballon is made by the material that friction factor is no more than 0.36 (MIU), for example methyl Si powder or nylon powder, and the powder of PA-12 for example, but be not limited thereto.Elasticity is methyl Si powder or the intrinsic character of nylon powder, prevents from thus owing to the friction of described microballon and light guide plate to produce on described microballon to scratch.
As mentioned above, on the interface between back coating 220 and the light guide plate, rub inevitably.Because the tensional modulus of elasticity of second adhesive resin is no more than 300MPa,, therefore can prevent the scuffing on the back coating 220 less than the tensional modulus of elasticity of the 900-1000MPa that is layered in the acryl resin on the typical light guide plate.That is to say,, can prevent the scuffing on back coating 220 and the light guide plate simultaneously according to the present invention.
Second adhesive resin can be made by the material that any tensional modulus of elasticity is no more than 300MPa.For example, second adhesive resin can be made by the curable urethane acrylate resin of UV, preferably by three (2-acrylyl oxy-ethyl) isocyanates-2-acrylic acid, (1-methyl ethylidene) two (4, the inferior phenoxy group-2 of 1-, 1-ethylenedioxy-2,1-second two bases) terpolymer of ester and 1-hydroxyl-cyclohexyl-phenyl ketone is made.Described terpolymer can be block polymer or random copolymers.The glass transition temperature of described terpolymer (Tg) is about 52 ℃, and number-average molecular weight is about 4500.
Back coating 220 provides the release for light diffusing board, thus the processibility when increasing assembling or reassemblying back light unit.In addition, back coating 220 prevents because the scuffing that causes with the friction of light guide plate, and back coating 220 comprises the diffusion particle that is used for large scale screen LCD.At this, release is meant the characteristic that prevents adhesion, and adhesion is meant light diffusing board and for example integration of light guide plate of adjacent light diffusing panel structure arranged.For release is provided, be necessary to make described microballon to give prominence to and reduce the friction factor of described microballon from the surface portion of back coating 220.Preferably, described microballon is from the outstanding 3-5 μ m in the surface of back coating 220.Described microballon reduces the contact area between light diffusing board and the light guide plate, thereby the contact between light diffusing board and the light guide plate is minimized.
Described microballon can be realized by the content of nonvolatile element the mixing coating solution of regulating bonding agent and particle from the outstanding of back coating 220 surfaces.That is to say, by regulating the fixedly number of spreading rod (bar coater) of solid matter content.Because the thickness of back coating 220 is uniformly before drying, and after drying the thickness of adhesive phase reduce and particle grain size constant, thereby described microballon can be from the outstanding about 3 μ m in the surface of back coating 220.
When described microballon from the thickness of the surperficial outshot of back coating 220 during less than 3 μ m, the adhesion of back coating 220 and light guide plate may appear.On the other hand, during greater than 5 μ m, may on light guide plate, produce scuffing from the thickness of the surperficial outshot of back coating 220 when described microballon.
Dust or contaminating impurity that back coating 220 can be manufactured occurs during back light unit.In order to prevent the pollution of above-mentioned back coating 220, back coating 220 can further comprise antistatic agent.Antistatic agent is not limited to certain material, but can use any this area product commonly used.
Fig. 6 is the decomposition diagram of liquid crystal display backlight unit, has applied the light diffusing board according to another embodiment of the invention on it.With reference to figure 6, three layers multilayered light diffuser plates 630 are stacked on the light emission surface of light guide plate 620, light guide plate 620 uses cold-cathode fluorescence lamp as light source 600.Cremasteric reflex plate 610 on another surface of light guide plate 620, this surface is opposite with the light emission surface of light guide plate 620.Although diagram has three layers according to the multilayered light diffuser plate 630 of this embodiment, multilayered light diffuser plate 630 can have two-layer or four layers.The conventional prism sheet that the rectilinearity of raising light increases its brightness is very expensive, therefore increases production cost.Yet the overlapped multilayered light diffuser plate of the present invention of light diffusion particles layer reduces production costs when the rectilinearity that improves light increases its brightness.
Hereinafter, the method for making the high-luminance light diffusing panel of liquid crystal display backlight unit according to the preferred embodiment of the invention is described.
Described method comprises:
(S1) preparation comprises the optical diffusion layer solution of light diffusion particles, first adhesive resin and solvent, described light diffusion particles has and is no more than 15% change in particle size coefficient, described change in particle size coefficient is represented by following formula, and described solvent has 0.82-1.0g/cm 3Proportion,
[expression formula]
Variation factor=(standard deviation ÷ mean value) * 100;
(S2) optical diffusion layer solution is coated on the surface of the substrate of making by polyethylene terephthalate (PET), and dry coated solution; With
(S3) form back coating, described back coating comprise friction factor be no more than 0.36 (MIU) for microballon with at another lip-deep second adhesive resin of pet substrate.In step S1, described light diffusion particles can comprise two kinds of particles with different average-sizes.
In step S1, when the proportion of solvent less than 0.82g/cm 3The time, the dispersiveness of light diffusion particles reduces in the solvent, so light diffusion particles is deposited in the described solvent during the course.Therefore, described solution must stir once more.On the other hand, when the proportion of described solvent greater than 1.0g/cm 3The time, it is heavier than first adhesive resin that described solvent becomes, and therefore after coating, can be enriched in first adhesive resin below.As a result, after drying stain can appear.The mixed solution that can use butyl acetate and dimethylbenzene is as being solvent.But solvent is not limited thereto, and has 0.82-1.0g/cm 3The various materials of proportion all can be used as solvent.Under the situation of ratio of solvent reclosing dipped beam diffusion particle proportion, light diffusion particles is evenly distributed in the solvent during can be from the course of dissolution to the coating procedure.Therefore, in this case, in a period of time, there is not the problem of light diffusion particles precipitation.Under situation along with the passage light diffusion particles precipitation that applies the time, back more production batch in the light diffusion particles amount of distributing just few more.As a result, although haze value reduces, light diffusion efficient reduces a lot.On the other hand, more early produce batch in the light diffusion particles amount of distributing just many more, make to be difficult in each batch light diffusion particles is arranged in one deck.In addition, the serious haze value deviation of local appearance in each batch.
After this, light diffusion particles is dropped in the solvent.At this, regulate the size of light diffusion particles, make the change in particle size coefficient of light diffusion particles be no more than 15%.The size adjustment of light diffusion particles can be undertaken by various filtrators, and filtrator is made by cotton, nylon, porosint, metal fibre etc.In order to improve filtration efficiency, can use the method that produces pressure reduction across filtrator, or use the centrifuging principle.In addition, can use the ultrafiltration that utilizes collodion membrane or viscose paper.Can be in addition in solvent, drop into other and input light diffusion particles and have the light diffusion particles of particle diameter mean value difference.The further feature of light diffusion particles is basic identical or similar with the feature of above-mentioned light diffusing board, therefore omits detailed description.
First adhesive resin is dissolved in the optical diffusion layer solution.First adhesive resin must have to the high adhesion of substrate 210 and with the compatibility of light diffusion particles.In addition, the light diffusion particles that contains the 40-140 weight portion in per 100 weight portions, first adhesive resin.
Do not limit the material of first adhesive resin.Preferably, use with the roughly the same acryl resin of the refractive index of PMMA as first adhesive resin.
For thermotolerance, abrasion resistance and the stickability that improves first adhesive resin, can in the composition of optical diffusion layer, add rigidizer.
After this, in order to prepare the optical diffusion layer solution of the light diffusion particles that wherein evenly distributes, can use conventional stirrer.At this, mix or dispersion process was carried out under 100-300rpm 1 hour, make light diffusion particles be dispersed in the solution, subsequently solution froth breaking foam 30 minutes under about 50-100rpm.In above-mentioned mixing condition, application mix speed makes light diffusion particles be dispersed in the solution and makes solution effectively eliminate foam.When mixing velocity is too high, produce a large amount of bubbles in the solution.On the other hand, cross when low, prolong the required time of manufacture process, and reduce the throughput rate of light diffusing board when mixing velocity.
After this,, optical diffusion layer solution is coated to a surface of the substrate of making by polyethylene terephthalate (PET) at step S2, and subsequent drying.
At this, substrate is made by PET, and it has high-fire resistance and processibility.In addition, described substrate can be selected from following a kind of material and makes: polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), Polyethylene Naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyene propyl ester (polyallylate), polyimide, polycarbonate (PC), Triafol T (TAC) and cellulose acetate propionate (CAP)., as long as above-mentioned substance has high-fire resistance and processibility.
The thickness of described pet substrate is 50-250 μ m.Describe the further feature of substrate above, thereby omitted detailed description.
After this, optical diffusion layer solution is coated on the pet substrate.At this, can use various painting methods, for example spin-coating method, silk screen cover are coated with (screen mask coating) and rod is coated with (bar coating) method.Preferably, use suitable large-scale production and quantity-produced rod to be coated with method.When using rod to be coated with method, the thickness of optical diffusion layer solution with about 20 μ m can be coated on the pet substrate.Afterwards, the dry pet substrate that applies optical diffusion layer solution.At this, can mode alone or in combination use various drying means, for example heated air seasoning, infrared (IR) seasoning and ultraviolet (UV) seasoning.After above-mentioned dry run, the solvent composition evaporation in the optical diffusion layer solution of coating, thus form optical diffusion layer.
At last, in step S3, another the lip-deep back coating that is formed on pet substrate comprises that friction factor is no more than the microballon and second adhesive resin of 0.36 (MIU).
Because friction factor is no more than 0.36 (MIU), thereby described microballon can have release, and can prevent since with for example scuffing on the light diffusing board that causes of light guide plate friction of other element that is positioned at the light diffusing board back side.More than describe the further feature of described microballon, thereby omitted detailed description.
The friction factor of described microballon is more little, and then the advantage of described microballon is many more.Preferably, the friction factor of described microballon is no more than 0.36 (MIU).For example, described microballon can be made by the material that friction factor is no more than 0.36 (MIU), for example methyl Si powder or nylon powder, and PA-12 powder for example, but be not limited thereto.That is to say that described microballon can be made by any materials, as long as the average friction coefficient of material is no more than 0.36 (MIU).
In order to dissolve the described microballon and second adhesive resin, second adhesive resin and microballon are dropped into solvent.Described solvent is not limited to predetermined substance, but can use any this area material commonly used, for example methyl ethyl ketone and toluene.
For second adhesive resin, can use any material that release, resistance to marring and tensional modulus of elasticity are no more than 300MPa that has.Second adhesive resin is preferably made by the curable urethane acrylate resin of UV, more preferably by three (2-acrylyl oxy-ethyl) isocyanates-2-acrylic acid, (1-methyl ethylidene) two (4, the inferior phenoxy group-2 of 1-, 1-ethylenedioxy-2,1-second two bases) terpolymer of ester and 1-hydroxyl-cyclohexyl-phenyl ketone is made.
In addition, can in solvent, add antistatic agent.Antistatic agent is not limited to predetermined substance, but can use this area product commonly used.
After this, in order to form back coating, should make the solvent that comprises the microballon and second adhesive resin through mixed process.Can use the mixed method identical to carry out mixed process with mixed light diffusing layer solution among the step S1.
After this, on another surface of pet substrate, described substrate has the optical diffusion layer that forms in step S1, and subsequent drying with the solvent coating that evenly is mixed with the microballon and second adhesive resin.Use with step S1 in the identical drying means of dry optical diffusion layer solution.
Hereinafter, be described in more detail the present invention based on following examples.Yet, should not think that the present invention is limited by the description of embodiment.
Embodiment 1
Preparing optical diffusion layer solution through the following steps, is 1.49 acryl resin, 5g as the polyisocyanate of rigidizer and 75g by polymethylmethacrylate (PMMA with the 100g refractive index; By Japanese SokenChemical ﹠amp; Engineering Co., Ltd. produces) (proportion is 0.878g/cm with containing 112g butyl acetate and 48g dimethylbenzene for the particle made 3And boiling point is 133.29 ℃) solvent prepare mixed solution, the particle that described polymethylmethacrylate is made as light diffusion particles and refractive index be 1.49, proportion is 1.19g/cm 3, be of a size of 20 μ m, the change in particle size coefficient was 7%, makes mixed solution experience dispersion process 1 hour under 1.000rpm with the homogeneous stirrer, with about 2 hours of mixed solution froth breaking foam.Use rod to be coated with machine optical diffusion layer solution is coated on the surface of pet substrate that thickness is 125 μ m, dry then.Thus, obtain being coated with on it PET plate that thickness is the optical diffusion layer of 20 μ m.After this, preparation back coating solution is as follows: with the 100g glass transition temperature is that about 52 ℃ and tensional modulus of elasticity are that the curable urethane acrylate resin of the UV of 250MPa is (by Natoko Paint Co., Ltd., " SB-243 " produces), 5g is that the microballon that the methyl silicon of 0.32 (MIU) is made is dissolved in the mixed solution that contains 50g toluene and 50g methyl ethyl ketone as the non-ionic surfactant of antistatic agent and 2g by friction factor.Use rod be coated with machine with the back coating solution coat on another surface of the PET plate with optical diffusion layer, then in air oven in 100 ℃ dry 30 seconds down.Subsequently, use radiation intensity to be 600mJ/cm 2Harden coating on the PET plate of UV line.Thereby, making light diffusing board, it comprises and has the back coating that thickness is the outstanding microballon of 4 μ m.
Embodiment 2
Prepare optical diffusion layer solution through the following steps: with the 100g refractive index is 1.49 unsaturated polyester resin, 5g as the polyisocyanate of rigidizer and 75g by polymethylmethacrylate (PMMA; SokenChemical ﹠amp by Japan; Engineering Co., Ltd. produces) (proportion is 0.879g/cm with containing 65g butyl acetate and 16g dimethylbenzene for the particle made 3And boiling point is 131.86 ℃) solvent prepare mixed solution, the particle that described polymethylmethacrylate is made as light diffusion particles and refractive index be 1.49, proportion is 1.19g/cm 3, be of a size of 10 μ m, the change in particle size coefficient was 7%, makes mixed solution experience dispersion process 1 hour under 1.000rpm with the homogeneous stirrer, with about 2 hours of mixed solution froth breaking foam.Use rod to be coated with machine optical diffusion layer solution is coated on the surface of pet substrate that thickness is 125 μ m, dry then.Thus, obtain being coated with on it PET plate that thickness is the optical diffusion layer of 20 μ m.After this, preparation back coating solution is as follows: with the 100g tensional modulus of elasticity is that the curable urethane acrylate resin of the UV of 250MPa is (by Natoko Paint Co., Ltd., " SB-243 " produces), 5g is that the microballon that the methyl silicon of 0.34 (MIU) is made is dissolved in the mixed solution that contains 50g toluene and 50g methyl ethyl ketone as the non-ionic surfactant of antistatic agent and 2g by friction factor.Use rod to be coated with machine and back coating solution is coated on another surface of the PET plate with optical diffusion layer, following dry 30 seconds in 100 ℃ in air oven then.Subsequently, use radiation intensity to be 600mJ/cm 2Harden coating on the PET plate of UV line.Thereby, making light diffusing board, it comprises and has the back coating that thickness is the outstanding microballon of 4 μ m.
Embodiment 3
Contain 90g butyl acetate and 60g dimethylbenzene (proportion is 0.876g/cm except using 3And boiling point is 134.7 ℃) solvent prepare outside the mixed solution, use with embodiment 1 in identical mode make light diffusing board.
Embodiment 4
Prepare optical diffusion layer solution through the following steps: with the 100g refractive index is 1.49 acryl resin, 5g as the polyisocyanate of rigidizer and 126g by polymethylmethacrylate (PMMA; SokenChemical ﹠amp by Japan; Engineering Co., Ltd. produces) particle made and 14g be by polymethylmethacrylate (PMMA; Soken Chemical ﹠amp by Japan; Engineering Co., Ltd. produces) (proportion is 0.878g/cm with containing 162g butyl acetate and 69g dimethylbenzene for the particle made 3And boiling point is 133.29 ℃) solvent prepare mixed solution, the refractive index of the particle that described 126g is made by polymethylmethacrylate is 1.49, proportion is 1.19g/cm 3, be of a size of 20 μ m, the change in particle size coefficient is 7%, the refractive index of the particle that described 14g is made by polymethylmethacrylate is 1.49, proportion is 1.19g/cm 3, be of a size of 10 μ m, the change in particle size coefficient was 9.5%, makes mixed solution experience dispersion process 1 hour under 1.000rpm with the homogeneous stirrer, with about 2 hours of mixed solution froth breaking foam.Use rod to be coated with machine optical diffusion layer solution is coated on the surface of pet substrate that thickness is 125 μ m, dry then.Thus, obtain being coated with on it PET plate that thickness is the optical diffusion layer of 20 μ m.After this, preparation back coating solution is as follows: with the 100g glass transition temperature is that about 52 ℃ and tensional modulus of elasticity are that the curable urethane acrylate resin of the UV of 250MPa is (by Natoko Paint Co., Ltd., " SB-243 " produces), 5g is that the microballon that the methyl silicon of 0.32 (MIU) is made is dissolved in the mixed solution that contains 50g toluene and 50g methyl ethyl ketone as the non-ionic surfactant of antistatic agent and 2g by friction factor.Use rod to be coated with machine and back coating solution is coated on another surface of the PET plate with optical diffusion layer, following dry 30 seconds in 100 ℃ in air oven then.Subsequently, use radiation intensity to be 600mJ/cm 2Harden coating on the PET plate of UV line.Thereby, making light diffusing board, it comprises and has the back coating that thickness is the outstanding microballon of 4 μ m.
Comparing embodiment 1
Prepare optical diffusion layer solution through the following steps; With the 100g refractive index is that the curable urethane acrylate resin of 1.47 UV, 75g are by polymethylmethacrylate (PMMA; Soken Chemical ﹠amp by Japan; Engineering Co., Ltd. produces) particle and the 128g that make be used as the methyl ethyl ketone (MEK) of solvent (proportion be 0.802g/cm 3And boiling point is 79.6 ℃) mix and to prepare mixed solution, the refractive index of the described particle of being made by polymethylmethacrylate is 1.49, be of a size of 20 μ m, the change in particle size coefficient is 35%, make mixed solution under 1.000rpm, experience dispersion process 1 hour with the homogeneous stirrer, with about 2 hours of mixed solution froth breaking foam.Use rod to be coated with machine optical diffusion layer solution is coated on the surface of pet substrate that thickness is 125 μ m, dry then.Thus, obtain being coated with on it PET plate that thickness is the optical diffusion layer of 20 μ m.After this, preparation back coating solution is as follows: be about 88 ℃ thermoset acrylics adhesive resin (the AEKYUNG CHEMICAL by Korea S makes), 3g as the non-ionic surfactant of antistatic agent and 2g with the 100g glass transition temperature be that the microballon that the PMMA of 0.38 (MIU) makes is dissolved in the 70g toluene by friction factor.Use rod to be coated with machine and back coating solution is coated on another surface of the PET plate with optical diffusion layer, following dry 30 seconds in the air oven then in 100 ℃.Thereby, making light diffusing board, it comprises and has the back coating that thickness is the outstanding microballon of 5 μ m.
Experimental example 1
By the following method assessment the foregoing description 1-4 and the light diffusing board of comparing embodiment 1.
(1) resistance to marring
Observe scuffing on the light diffusing board by the friction test of the light guide plate that is in contact with it.At this, use the Shinto Scientific Co. of Japan, the character of surface test unit " HEIDON-14DR " that Ltd. makes.Test condition is set at: reciprocating speed is that 4500mm/min, reciprocal distance are that 15mm, reciprocal time are 2000 and to apply weight be 50g.By the macroscopic evaluation result.
Fig. 3 A is the figure that illustrates according to the surface state after the light diffusing board friction test of comparing embodiment 1 manufacturing, and Fig. 3 B is the figure that illustrates according to the surface state after the light diffusing board friction test of embodiments of the invention 4 manufacturings.With reference to figure 3A and 3B, can see, when light diffusing board contacts with light guide plate generation frictional property, form minority on the light diffusing board of the present invention and scratch, because the friction factor of microballon is little.Can also see,, therefore reduce scratching because the elasticity of second bonding agent guarantees the transportable distance of microballon.
(2) abrasion resistance assessment
In order to use the abrasion resistance (use CS-17 emery wheel and load be 1kg) of Taibo abrasion test instrument measurement, prepare the dish type sample of each light diffusing board according to each back coating of the light diffusing board of embodiment 4 and comparing embodiment 1 manufacturing.Emery wheel is installed on the sample, then rotation.Thereby wearing and tearing sample.Measure the weight of wearing and tearing sample then.The test findings of the light diffusing board that Fig. 5 obtains.
Fig. 5 is the figure of explanation according to the abrasion resistance test findings of the light diffusing board of embodiments of the invention 4 and comparing embodiment 1 manufacturing.With reference to figure 5, the ratio that is lowered into of the minimizing of the light diffusing board sample size of making according to comparing embodiment 1 and the rpm of emery wheel.On the other hand, the minimizing of the light diffusing board sample size of making according to embodiments of the invention 4 reaches about 300 just near zero up to emery wheel rpm, and the minimizing of light diffusing board sample size all keeps very little value from reaching at 1000 o'clock up to emery wheel rpm at this moment.In addition, according to visual check, second adhesive resin of the light diffusing board of making according to comparing embodiment 1 is peeled off.On the other hand, any part of second adhesive resin of the light diffusing board sample of making according to embodiment 4 is not peeled off.Thus, think that light diffusing board of the present invention has good abrasion resistance.
(3) brightness assessment
Use is measured by the BM7 equipment that TOPCON CORPORATION makes, and to take measurement of an angle be 1 °.9 zones altogether of measuring light diffusing panel.With 9 measured zone numberings.Fig. 4 is the synoptic diagram of explanation according to the brightness measurement zone of the light diffusing board of another embodiment of the invention.Table 1 illustrates the brightness in 9 zones of each light diffusing board made according to embodiment 1-4 and comparing embodiment 1 that uses that the said equipment measures.
Table 1
1 2 3 4 5 6 7 8 9 Mean flow rate Increment rate (%)
Embodiment 1 3737 3246 3293 3258 3521 3425 3178 3206 3078 3327 1.2
Embodiment 2 3713 3218 3265 3238 3509 3389 3154 3178 3086 3306 0.5
Embodiment 3 3792 3281 3325 3313 3569 3433 3214 3262 3142 3370 2.5
Embodiment 4 3836 3309 3345 3317 3593 3485 3269 3305 3178 3404 3.5
Comparing embodiment 1 3689 3198 3242 3214 3493 3401 3126 3166 3066 3288 0.0
As shown in table 1, measure the brightness of the regional 1-9 of the light diffusing board of making according to comparing embodiment 1, and calculate mean flow rate.Subsequently, calculate the mean flow rate of each light diffusing board of making according to embodiment 1-4, and compare with the mean flow rate of the light diffusing board of making according to comparing embodiment 1.Thereby calculating is according to the increment rate of the mean flow rate of each light diffusing board of embodiment 1-4 manufacturing.That is to say that the mean flow rate of the light diffusing board that will make according to comparing embodiment 1 is as reference brightness.Reference table 1 can be seen, the brightness increment rate of the light diffusing board of making according to embodiment 1-4 is respectively 1.2%, 0.5%, 2.5% and 3.5%.
Can confirm from The above results, with because multilayer is arranged the low traditional light diffusing board of brightness that the birefringence of microballon causes relatively, light diffusing board of the present invention realized improving brightness according to the microballon of monolayer alignment, eliminate adhesion and reduce because the scuffing that produces thereon with the friction of the contiguous light guide plate in the light diffusing board back side.
It is evident that from top description, the invention provides the high-luminance light diffusing panel and the manufacture method thereof of liquid crystal display backlight unit, described light diffusing board increases brightness, reduces scuffing and elimination adhesion that the light diffusing board back side produces.
Although for illustration purpose discloses the preferred embodiments of the invention, it will be understood by those skilled in the art that under the situation that does not depart from the scope and spirit of the present invention in the claims, can carry out various changes, interpolation and replacement.

Claims (12)

1. light diffusing board that is used for liquid crystal display backlight unit comprises:
Substrate;
Optical diffusion layer is formed on the surface of substrate, and wherein optical diffusion layer is made by a kind of composition, and described composition comprises light diffusion particles, solvent and first adhesive resin, and described light diffusion particles has 1.0-1.2g/cm 3Proportion and be no more than 15% change in particle size coefficient, described change in particle size coefficient represents that by following formula described solvent has 0.82-1.0g/cm 3Proportion and 130-140 ℃ boiling point, be used for regulating the rate of deposition of light diffusion particles, the refractive index of described first adhesive resin and the refractive index difference of light diffusion particles are no more than 0.01,
[expression formula]
Variation factor=(standard deviation ÷ mean value) * 100; With
Back coating is formed on another surface of substrate, and wherein back coating comprises that friction factor MIU is no more than second adhesive resin that 0.36 microballon and tensional modulus of elasticity are not more than 300MPa.
2. according to the light diffusing board of claim 1, the solid matter content in the wherein said composition is 38-42%.
3. according to the light diffusing board of claim 1, wherein said solvent is the mixed solution that contains butyl acetate and dimethylbenzene.
4. according to the light diffusing board of claim 3, wherein said mixed solution comprises the butyl acetate of dimethylbenzene/100 weight portions of 20-150 weight portion.
5. according to the light diffusing board of claim 1, wherein said composition comprises first adhesive resin of light diffusion particles/100 weight portions of 40-140 weight portion.
6. according to the light diffusing board of claim 1, wherein said light diffusion particles comprises two kinds of particles with different average-sizes.
7. according to the light diffusing board of claim 1, the proportion of wherein said solvent is 0.86-1.0g/cm 3
8. according to the light diffusing board of claim 1, wherein said microballon is made by methyl Si powder or nylon powder.
9. according to the light diffusing board of claim 1, wherein said second adhesive resin is the urethane acrylate resin of ultraviolet-curing.
10. according to the light diffusing board of claim 9, the urethane acrylate resin of wherein said ultraviolet-curing is three (2-acrylyl oxy-ethyl) isocyanates-2-acrylic acid, (1-methyl ethylidene) two (4, the inferior phenoxy group-2 of 1-, 1-ethylenedioxy-2,1-second two bases) terpolymer of ester and 1-hydroxyl-cyclohexyl-phenyl ketone.
11. a manufacturing is used for the method for the light diffusing board of liquid crystal display backlight unit, comprising:
Preparation optical diffusion layer solution, described optical diffusion layer solution comprises light diffusion particles, solvent and first adhesive resin, described light diffusion particles has and is no more than 15% change in particle size coefficient, described change in particle size coefficient represents that by following formula the proportion of described solvent is 0.82-1.0g/cm 3,
[expression formula]
Variation factor=(standard deviation ÷ mean value) * 100;
Optical diffusion layer solution is coated on the surface of the substrate of making by polyethylene terephthalate, and dry coated solution; With
Form back coating, described back coating comprises that friction factor MIU is no more than 0.36 microballon and at another lip-deep second adhesive resin of polyethylene terephthalate substrate.
12. according to the method for claim 11, wherein said light diffusion particles comprises two kinds of particles with different average-sizes.
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