(19)
(11)EP 3 070 109 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
05.12.2018 Bulletin 2018/49

(21)Application number: 16152914.4

(22)Date of filing:  27.01.2016
(51)International Patent Classification (IPC): 
C08F 220/18(2006.01)
C09D 133/08(2006.01)
C08F 222/10(2006.01)

(54)

MULTILAYER POLYMER COMPOSITE FOR ENCAPSULATING QUANTUM DOTS

MEHRSCHICHTIGER POLYMERVERBUNDSTOFF ZUR EINKAPSELUNG VON QUANTENPUNKTEN

COMPOSITE DE POLYMÈRE MULTICOUCHE POUR ENCAPSULER DES POINTS QUANTIQUES


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 16.03.2015 US 201562133512 P

(43)Date of publication of application:
21.09.2016 Bulletin 2016/38

(73)Proprietors:
  • Rohm and Haas Electronic Materials LLC
    Marlborough, MA 01752 (US)
  • Rohm And Haas Electronic Materials Korea Ltd.
    Chungcheongnam-do 331-980 (KR)
  • Dow Global Technologies LLC
    Midland, MI 48674 (US)

(72)Inventors:
  • BAI, Zhifeng
    Midland, MI Michigan 48674 (US)
  • JOO, Jaebum
    Marlborough, MA Massachusetts 01752 (US)
  • SUNG, In-Kyung
    331-980 Cheonan (KR)
  • TAYLOR, James C
    Marlborough, MA Massachusetts 01752 (US)

(74)Representative: Houghton, Mark Phillip et al
Patent Outsourcing Limited 1 King Street
Bakewell, Derbyshire DE45 1DZ
Bakewell, Derbyshire DE45 1DZ (GB)


(56)References cited: : 
WO-A1-2014/028677
US-A1- 2014 264 193
WO-A1-2015/013225
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    FIELD OF THE INVENTION



    [0001] The present invention relates to a process for preparing a multilayer assembly comprising an outer layer on each side of a polymer composite containing quantum dots.

    BACKGROUND OF THE INVENTION



    [0002] Semiconductor quantum dots (QD) provide optical absorption and emission (photoluminescence PL or electroluminescence EL) behaviors that are significantly different from those of bulk materials. As the particle size decreases, effective energy bandgap (Eg), or available energy levels, increases and creates a blue shifted PL spectrum. This spectrum tunability by the particle size dependent quantum confinement effect within the same material is a critical advantage over conventional bulk semiconductors. Because of their unique optical properties, QD have been of great interest in many display and lighting applications. Most QD have inorganic shells with a larger bandgap material to confine electron and hole pairs within the core region and prevent any surface charge states. The outer shells are then capped by organic ligands to reduce trap states of the shell that can lead to reduced quantum yield (QY). Organic ligands help QD to disperse in organic/aqueous solvents. Typical organic ligands surrounding QD have relatively long alkyl chains which provide high solubility in non-polar solvents or monomers. Unfortunately, QD are very susceptible to photo-oxidation during light absorption/conversion process. Also, moisture can have similar impacts when ligands are not compatible. QD typically are encapsulated in a polymer matrix to protect them from adverse effects of water and oxygen. For example, US2010/0084629 discloses a variety of polymers as encapsulants. However, this reference does not disclose the polymer compositions described herein.

    SUMMARY OF THE INVENTION



    [0003] The present invention provides a multilayer assembly comprising an outer layer on each side of a polymer composite, the polymer composite comprising quantum dots and polymerized units of a compound of formula (I) having one (meth)acrylate ester substituent and a compound of formula (I) having two (meth)acrylate ester substituents in a weight ratio from 100:1 to 1:5, respectively,

    wherein R1 is hydrogen or methyl and R2 is a C6-C20 aliphatic polycyclic substituent.

    DETAILED DESCRIPTION OF THE INVENTION



    [0004] Percentages are weight percentages (wt%) and temperatures are in °C, unless specified otherwise. Operations were performed at room temperature (20-25 °C), unless specified otherwise. Boiling points are measured at atmospheric pressure (ca. 101 kPa). The term "(meth)acrylate" means acrylate or methacrylate. Quantum dots are well known in the art, see, e.g., US2012/0113672 and WO2015/013225.

    [0005] The polymer composite is part of a multilayer assembly which also comprises an outer layer on each side of the polymer composite. Preferably, the outer layer is an oxygen barrier which also inhibits passage of moisture. Preferably, the outer layer comprises a polymer film, preferably one comprising polyethylene terephthalate (PET), polyaryletherketones, polyimides, polyolefins, polycarbonate, polymethyl methacrylate (PMMA), polystyrene, or a combination thereof. Preferably, the outer layer further comprises oxides or nitrides, preferably silicon oxides, titanium dioxide, aluminum oxide, silicon nitrides or a combination thereof. Preferably the oxides or nitrides are coated on the surface of the polymer film facing the QD layer. Preferably, each outer layer comprises a polymer film having a thickness from 25 to 150 microns (preferably 50 to 100 microns) and an oxide/nitride layer having a thickness from 10 to 100 nm (preferably 30 to 70 nm). In some preferred embodiments of the invention, the outer layer comprises at least two polymer film layers and/or at least two oxide/nitride layers; different layers may be of differing composition. Preferably, the outer layers have a very low oxygen transmission rate (OTR, < 10-1 cc/m2/day) and low water vapor transmission rate (WVTR, < 10-2 g/m2/day). Preferably, the polymer film in the outer layers has a Tg from 60 to 200°C; preferably at least 90°C, preferably at least 100°C.

    [0006] Preferably, the thickness of the polymer composite is from 10 to 500 microns, preferably at least 20 microns, preferably at least 30 microns, preferably at least 40 microns; preferably no greater than 400 microns, preferably no greater than 300 microns, preferably no greater than 200 microns, preferably no greater than 150 microns. Preferably, the thickness of each outer layer is from 20 to 100 microns, preferably from 25 to 75 microns

    [0007] Preferably, the polymer composite is prepared by free radical polymerization of the resin prepared by mixing monomers, QD and other optional additives. Preferably, the resin is coated on a first outer layer prior to curing by typical methods, e.g., spin coating, slot die coating, gravure, ink jet and spray coating. Preferably, curing is initiated by exposing the resin to ultraviolet light or heat, preferably ultraviolet light, preferably in the UVA range.

    [0008] Preferably, R2 is a C7-C17 aliphatic polycyclic substituent, preferably R2 is a C8-C15 aliphatic polycyclic substituent. Preferably, R2 is a bridged polycyclic substituent; preferably a bicyclic, tricyclic or tetracyclic substituent; preferably a bicyclic or tricyclic substituent. Preferably, R2 is a saturated aliphatic substituent. Preferred structures for R2 include, e.g., adamantanes, bicyclo[2,2,1]alkanes, bicyclo[2,2,2]alkanes, bicyclo[2,1,1]alkanes and tricyclodecanes (e.g., tricyclo[5,2,1,02,6]decane); these structures may be substituted with alkyl, alkoxy groups, hydroxy groups or (meth)acrylate esters (i.e., the compound of formula (I) may have at least two (meth)acrylate ester substituents; preferably no more than two); preferably alkyl and alkoxy groups have from one to six carbon atoms, preferably one to four. Tricyclodecanes and bicyclo[2,2,1]alkanes are especially preferred, particularly tricyclo[5,2,1,02,6]decane, dimethanol dimethacrylate and isobornyl acrylate. The inner layer comprises polymerized units of a compound of formula (I) having one (meth)acrylate ester substituent and a compound of formula (I) having two (meth)acrylate ester substituents in a weight ratio from 10:1 to 1:2, respectively.

    [0009] Preferably, the polymer composite comprises from 0.01 to 5 wt% of quantum dots, preferably at least 0.03 wt%, preferably at least 0.05 wt%; preferably no more than 4 wt%, preferably no more than 3 wt%, preferably no more than 2 wt%. Preferably, quantum dots comprise CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs or a combination thereof.

    [0010] Preferably, ligands surrounding the inorganic part of quantum dots have non-polar components. Preferred ligands include, for example, .trioctyl phosphine oxide, dodecanethiol and fatty acid salts (e.g., stearate salts, oleic acid salts).

    [0011] Other additives which may be incorporated into the polymer composite include uv stabilizers, antioxidants, scattering agents to improve light extraction, and thickeners to increase viscosity (e.g., urethane acrylate oligomers). Preferred thickeners include urethane acrylates, cellulose ethers, cellulose acrylic esters, polystyrene polymers, polystyrene block copolymers, acrylic resin and polyolefin elastomers.. Preferably, polystyrene, acrylic and polyolefin thickeners have Mw from 50,000 to 400,000; preferably from 100,000 to 200,000. Preferably, cellulose ethers have Mw from 1,000 to 100,000.

    [0012] Urethane acrylate oligomers can be polyester type, polyether type, polybutadiene type, or polycarprolactone type. They can have difunctional, trifunctional, hexafunctional reactivities. Viscosities of oligomers can range from 1000 to 200,000 mPa-s (1000 to 200,000 cPs) at 50C. For non-polar ligand QDs, polybutadiene types are preferred.

    [0013] Preferably, the first inner layer comprises from 1 to 60 wt% urethane acrylates, preferably at least 5 wt%, preferably at least 10 wt%; preferably no more than 50 wt%, preferably no more than 40 wt%.

    [0014] Preferred forms for the polymer composite include, e.g., films, beads, strips, rods, cubes and plates. The polymer composite is useful in many applications, including, e.g., displays, lighting and medical applications. Preferred display applications include public information displays, signage, televisions, monitors, mobile phones, tablets, laptops, automotive dashboards and watches.

    EXAMPLES


    SAMPLE PREPARATION FOR EXAMPLES



    [0015] All samples were prepared by lamination of the resin formulations between two i-Component PET barrier films. Approximately 2mL of resin was dispensed on the bottom film and the top has applied with a gap coating bar with gap setup (0.25 - 0.30 mm (10mil - 12mil)) based on desired film thickness. Samples were cured in a Fusion UV F300S curing system with UVA 400mJ/cm2, unless otherwise noted. Film thicknesses were determined by measurement of the cured films with a micrometer and then subtracting out the barrier film thickness. Photoluminescent Quantum Yield (PLQY), peak emission wavelength (PWL) and full-width half-max of the emission peak (FWHM) were measured with a Hamamatsu C9920-02G integrating sphere. Edge ingress was determined by image analysis of 2.54 cm x 2.54 cm (1"x1") samples aged on a bare backlight unit.

    EXAMPLE 1: Comparison of linear aliphatic monomers to cycloaliphatic monomers



    [0016] Curing condition: UVA 400mJ/cm2 x 4times
     Formulation AFormulation BFormulation CFormulation D
    Nanoco CFQD1 quantum dot 0.7 0.7 0.7 0.7
    Lauryl acrylate 35.8 0 0 0
    Isobornyl acrylate 0 35.8 32.7 29.6
    Tricyclodecane dimethanol diacrylate 0 0 5 10
    IRGACURE I-819 2.5 2.5 2.5 2.5
    Trimethylolpropane tris(3-mercaptopropionate 4 4 4 4
    Trimethylolpropane triacrylate 14 14 14 14
    CN996 oligomer 42 42 40.1 38.2
    BaSO4 1 1 1 1

    1. Cadmium-free quantum dots as described in US7588828



    [0017] CN996 oligomer is an aliphatic urethane acrylate oligomer, from Sartomer America.]

    Coating thickness:



    [0018] 
    FilmIDQD display film thickness mm
    FormulationA 0.117
    FormulationB 0.110
    FormulationC 0.135
    FormulationD 0.121

    Edge ingress damage after 1000Cd/m2 blue BLU



    [0019] 
     24Hr96hous120hr168hr336hr
    FomulationA 0.764417 1.276159   1.727667 2.248431
    FomulationB 0 0.336642   0.414909 0.46959
    FormulationC 0   0.333269 0.382147 0.435117
    FormulationD 0   0.26699 0.294882 0.427014

    EXAMPLE 2: Examples of resin with antioxidant (IRGAFOS 168) and light stabilizer (TINUVIN 5100)



    [0020] 
     123
    Nanoco CFQD quantum dot 0.14 0.14 0.14
    Isobornyl acrylate 46.61 46.11 45.11
    Tricyclodecane dimethanol diacrylate 30 30 30
    IRGACURE I-819 1.5 1.5 1.5
    IRGAFOS 168 0 0.5 0
    TINUVIN 5100 0 0 1.5
    BR-641D oligomer 17 17 17
    TIPURE 706 TiO2 particle 7.5 7.5 7.5


    [0021] BR-641D oligomer is a polybutadiene urethane acrylate oligomer, from Dymax.]
    TIPURE 706 is available from Dupont.

    [0022] Curing: 400mJ/cm2. Single pass
    IDavg (µm)
    1 60
    2 72
    3 58
     PLQYQY stdevPWLFWHM
    1 37.77 1.86 517.95 57.76
    2 42.77 1.17 518.20 56.55
    3 42.53 0.65 519.68 55.07

    EXAMPLE 3:



    [0023] Example of resin prepared with polymer viscosity modifier (KRATON G1650)
     Formulation AFormulation B
    Nanoco CFQD™ quantum dot 0.2 0.2
    Isobornyl acrylate 68.5 58.7
    Tricyclodecane dimethanol diacrylate 20 30
    IRGACURE I-819 1.5 1.5
    KRATON G1650 7.8 7.6
    Zoco 101 ZnO particle 2 2


    [0024] Zoco101 is available from Zochem.
    IDavg (µm)
    Formulation A 39
    Formulation B 22
     PLQYPWLFWHM
    Formulation A 41.4 638.9 59.6
    Formulation B 40.5 648.3 61.4

    EXAMPLE 4:



    [0025] Examples of resin prepared with various ratios of cycloaliphatic monomers
     1234
    Nanoco CFQD quantum dot 0.05 0.05 0.05 0.05
    Isobornyl acrylate 60.7 50.7 40.7 30.7
    Tricyclodecane dimethanol diacrylate 20 30 40 50
    IRGACUREI-819 1.5 1.5 1.5 1.5
    BR-641D Oligomer 17 17 17 17
    TIPURE 706 TiO2 particle 0.75 0.75 0.75 0.75
    IDavg (µm)
    1 132
    2 133
    3 107
    4 123
    Sample IDAVG QYSTDEV QYAVG PLAVG FWHMAVG PL REDAVG FWHM RED
    1 60.40 1.14 519.03 56.72 634.19 63.19
    2 51.43 0.31 519.70 55.45 643.86 63.90
    3 47.33 0.87 515.20 61.46 640.14 61.53
    4 45.13 0.25 529.94 70.81 642.13 64.27

    Edge Ingress damage (mm) after storage in 60°C/90% Relative Humidity



    [0026] 
     72hr168hr336hr
    1 1.72 3.17 5.77
    2 1.49 2.33 3.78
    3 0.86 1.50 2.41
    4 0.64 1.10 1.78

    EXAMPLE 5:



    [0027] Examples of resin prepared with small loadings of linear aliphatic monomers as compatibilizing additives
     79
    Nanoco CFQD™ quantum dot 0.04 0.04
    Isobornyl acrylate 53.71 49.73
    Lauryl methacrylate 0 3.96
    Tricyclodecane dimethanol diacrylate 19 19
    IRGACUREI-819 1.5 1.5
    BR-641D Oligomer 25 25
    TIPURE 706 TiO2 particle 0.75 0.75
    IDavg (µm)
    7 53
    9 45
     PLQYQY stdevPWLFWHM
    7 32.9 0.44 637.7 66.6
    9 36.9 0.55 637.4 64.1

    EXAMPLE 6: Examples of resin prepared with two different quantum dot mixtures.



    [0028] 
     1
    Nanoco CFQD™ green quantum dot 0.28
    Nanoco CFQD™ red quantum dot 0.07
    Isobornyl acrylate 40.525
    Tricyclodecane dimethanol diacrylate 30
    IRGACURE I-819 15
    KRATON G1652 9.125
    TINUVIN 123 1.5
    Zoco 101 ZnO particle 3.5
    IDavg (µm)
    1 104


    [0029] The cured film was placed between the light guide plate and prism film/brightness enhancement film of blue LED based backlight unit (BLU). BLU spectrum was measured using GL Spectis spectroradiometer. Color coordinate of final spectrum and color gamut coverage were calculated based on the BLU spectrum and an available color filter dataset.
     CIExCIEyCIEz
    BLU white 0.251 0.239 0.510
    Panel blue 0.157 0.057 0.786
    Panel green 0.246 0.694 0.060
    Panel red 0.677 0.312 0.011
    Panel white 0.262 0.276 0.461
     Color gamut coverage (vs.sRGB)
    % area 138
    % overlap 100


    [0030] Wavelength dependent emission spectrum normalized by the maximum peak intensity.
    wavelengthblue LED BLUblue LED BLU + film
    400 0.001799541 -0.001718333
    405 0.005268541 0.000577671
    410 0.016890786 0.007631886
    415 0.04931601 0.028007319
    420 0.122586966 0.081087041
    425 0.265607892 0.199143175
    430 0.511079238 0.430434011
    435 0.833891183 0.774125936
    440 1 0.991670706
    445 0.864842533 0.898225587
    450 0.57331293 0.61091274
    455 0.339906003 0.363499942
    460 0.199517423 0.211355149
    465 0.11107564 0.117340634
    470 0.063158431 0.069497716
    475 0.037262744 0.047296871
    480 0.021987463 0.037964307
    485 0.012910007 0.038338101
    490 0.007966666 0.046298448
    495 0.005238596 0.061020953
    500 0.003220408 0.084885063
    505 0.002313958 0.120505083
    510 0.001915676 0.168584908
    515 0.001401463 0.225699285
    520 0.000859068 0.285145182
    525 0.000923902 0.335413153
    530 0.00049007 0.362652675
    535 0.00069194 0.36050481
    540 0.00045016 0.335668494
    545 0.000403799 0.293595319
    550 7.34827E-05 0.244397867
    555 0.000133896 0.194297165
    560 3.49273E-05 0.151623188
    565 -1.87684E-05 0.11996641
    570 -4.49488E-05 0.096343986
    575 7.58107E-05 0.078691345
    580 7.31695E-05 0.06614026
    585 -0.000314182 0.057090482
    590 -0.000335826 0.052079524
    595 7.39134E-05 0.051888975
    600 -0.000278013 0.05624342
    605 -0.000346791 0.066283223
    610 -0.000459618 0.083073783
    615 -0.000457154 0.106960422
    620 -0.000748242 0.13759379
    625 -0.000716673 0.175583563
    630 -0.000522994 0.215143612
    635 -0.000838996 0.249540865
    640 -0.000543793 0.274591557
    645 -0.000512196 0.286686784
    650 -0.000598369 0.287997624
    655 -0.000886423 0.279322187
    660 -0.000449722 0.261573281
    665 -0.000750665 0.238296318
    670 -0.00101099 0.210964628
    675 -0.001141071 0.183288842
    680 -0.001147285 0.157807348
    685 -0.001269858 0.136076083
    690 -0.001727023 0.116518628
    695 -0.00166393 0.098685064
    700 -0.001698529 0.0847294
    705 -0.001551849 0.070714339
    710 -0.00270767 0.057980488
    715 -0.003036792 0.046570789
    720 -0.004571635 0.036315994
    725 -0.009056433 0.02743212
    730 -0.009250231 0.017445023
    735 -0.0078037 0.010043558
    740 -0.007486296 0.00546386
    745 -0.007656289 0.004965795
    750 -0.00738996 0.00555811



    Claims

    1. A multilayer assembly comprising an outer layer on each side of a polymer composite, the polymer composite comprising quantum dots and polymerized units of a compound of formula (I) having one (meth)acrylate ester substituent and a compound of formula (I) having two (meth)acrylate ester substituents in a weight ratio from 100:1 to 1:5, respectively,

    wherein R1 is hydrogen or methyl and R2 is a C6-C20 aliphatic polycyclic substituent.
     
    2. The multilayer assembly of claim 1 in which R2 is a bridged polycyclic substituent.
     
    3. The multilayer assembly of claim 2 in which R2 is a C7-C17 bridged polycyclic substituent.
     
    4. The multilayer assembly of claim 3 in which R2 has a bicyclo[2,2,1]alkane or tricyclodecane ring system.
     
    5. The multilayer assembly of claim 4 in which the quantum dots comprise CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs or a combination thereof.
     
    6. The multilayer assembly of claim 5 further comprising a urethane acrylate, a cellulose ether, a cellulose acrylic ester, a polystyrene polymer, a polystyrene block copolymer, an acrylic resin or a polyolefin elastomer.
     
    7. The multilayer assembly of claim 5 further comprising a scattering agent.
     
    8. The multilayer assembly of claim 7 further comprising an antioxidant or UV light stabilizer.
     
    9. The multilayer assembly of claim 5 which is a film.
     


    Ansprüche

    1. Eine mehrschichtige Anordnung, beinhaltend eine äußere Schicht auf jeder Seite eines Polymerverbundstoffs, wobei der Polymerverbundstoff Quantenpunkte und polymerisierte Einheiten einer Verbindung der Formel (I) mit einem (Meth)acrylatestersubstituenten und einer Verbindung der Formel (I) mit zwei (Meth)acrylatestersubstituenten in einem Gewichtsverhältnis von jeweils 100 : 1 bis 1 : 5 beinhaltet,

    wobei R1 Wasserstoff oder Methyl ist und R2 ein aliphatischer polycyclischer C6-C20-Substituent ist.
     
    2. Mehrschichtige Anordnung gemäß Anspruch 1, wobei R2 ein verbrückter polycyclischer Substituent ist.
     
    3. Mehrschichtige Anordnung gemäß Anspruch 2, wobei R2 ein verbrückter polycyclischer C7-C17-Substituent ist.
     
    4. Mehrschichtige Anordnung gemäß Anspruch 3, wobei R2 ein Bicyclo[2,2,1]alkan- oder Tricyclodecan-Ringsystem aufweist.
     
    5. Mehrschichtige Anordnung gemäß Anspruch 4, wobei die Quantenpunkte CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs oder eine Kombination davon beinhalten.
     
    6. Mehrschichtige Anordnung gemäß Anspruch 5, ferner beinhaltend ein Urethanacrylat, einen Celluloseether, einen Celluloseacrylester, ein Polystyrolpolymer, ein Polystyrolblockcopolymer, ein Acrylharz oder ein Polyolefinelastomer.
     
    7. Mehrschichtige Anordnung gemäß Anspruch 5, ferner beinhaltend ein Streumittel.
     
    8. Mehrschichtige Anordnung gemäß Anspruch 7, ferner beinhaltend ein Antioxidationsmittel oder einen UV-Licht-Stabilisator.
     
    9. Mehrschichtige Anordnung gemäß Anspruch 5, bei der es sich um eine Folie handelt.
     


    Revendications

    1. Un ensemble multicouche comprenant une couche externe sur chaque côté d'un composite à base de polymères, le composite à base de polymères comprenant des points quantiques et des unités polymérisées d'un composé de formule (I) ayant un substituant ester de (méth)acrylate et un composé de formule (I) ayant deux substituants ester de (méth)acrylate dans un rapport en poids allant de 100/1 à 1/5, respectivement,

    où R1 est l'hydrogène ou un méthyle et R2 est un substituant polycyclique aliphatique en C6 à C20.
     
    2. L'ensemble multicouche de la revendication 1 dans lequel R2 est un substituant polycyclique ponté.
     
    3. L'ensemble multicouche de la revendication 2 dans lequel R2 est un substituant polycyclique ponté en C7 à C17.
     
    4. L'ensemble multicouche de la revendication 3 dans lequel R2 a un système de cycle bicyclo[2,2,1]alcane ou tricyclodécane.
     
    5. L'ensemble multicouche de la revendication 4 dans lequel les points quantiques comprennent du CdS, du CdSe, du CdTe, du ZnS, du ZnSe, du ZnTe, du HgS, du HgSe, du HgTe, du GaN, du GaP, du GaAs, du InP, du InAs ou une combinaison de ceux-ci.
     
    6. L'ensemble multicouche de la revendication 5 comprenant en sus un acrylate d'uréthane, un éther de cellulose, un ester acrylique de cellulose, un polymère polystyrène, un copolymère séquencé polystyrène, une résine acrylique ou un élastomère de polyoléfine.
     
    7. L'ensemble multicouche de la revendication 5 comprenant en sus un agent de diffusion.
     
    8. L'ensemble multicouche de la revendication 7 comprenant en sus un antioxydant ou un stabilisateur à la lumière ultraviolette.
     
    9. L'ensemble multicouche de la revendication 5 qui est un film.
     






    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description