Modified phosphors and compositions thereof

Abstract

A modified phosphor is described comprising phosphor particles and at least one amphiphilic agent. Compositions comprising the modified phosphor and at least one polymer are also described.

1 . A modified phosphor comprising phosphor particles and at least one amphiphilic agent coated thereon, said modified phosphor being selected among phosphors which contain at least one element selected from the group consisting of the rare earth elements, zinc and manganese and having: an external quantum yield equal to or greater than 40% over at least an excitation wavelength comprised between 350 nm and 440 nm; an absorption equal to or less than 15% at a wavelength greater than 440 nm; and a maximum in the emission spectrum in a range of wavelengths comprised between 440 nm and 900 nm. 
     
     
         2 . A modified phosphor comprising particles of a phosphor with at least one amphiphilic agent on their surface. 
     
     
         3 . A modified phosphor according to  claim 1 , wherein the particles of the modified phosphor are dispersible in a polymer. 
     
     
         4 . The modified phosphor according to  claim 1 , wherein the phosphor is selected from the group consisting of the aluminates doped with at least one rare earth element and/or manganese, the europium-doped phosphates or halophosphates, the europium- and/or manganese-doped silicates, the cerium-doped rare earths borates or silicates, the rare earth oxysulphurs, the rare earths vanadates, the zinc compounds doped with maganese, zinc, silver and/or copper. 
     
     
         5 . The modified phosphor according to  claim 1 , wherein the phosphor is selected from the aluminates:
 of formula (Ia) or (Ib): A 1 MgAl 10 O 17 :Eu 2+  (Ia) or A 1 MgAl 10 O 17 :Eu 2+ ,Mn 2+  (Ib) wherein A 1  represents at least one of Ba, Sr, or Ca alone or in combination;   of formula (II) or (IIa) or (IIb): a(M 1-d M 1   d O).b(Mg 1-e M 2   e O).c(Al 2 O 3 ) (II); a(M 1-d Eu d O).b(Mg 1-e Mn e O).c(Al 2 O 3 ) (IIa); a(Ba 1-d M 1   d O).b(Mg 1-e M 2   e O).c(Al 2 O 3 ) (IIb) wherein
 M is at least one element selected from Ba, Sr and Ca; 
 M 1  denotes a rare earth, preferably at least one of Gd, Tb, Y, Yb, Eu, Nd or Dy, more preferably Eu; and 
 M 2  denotes at least one of Zn, Mn or Co, preferably Mn; and wherein a, b, c, d and e satisfy the following relationships: 0.25≦a≦2.00; 0<b≦2.00; 3.00≦c≦9.00; 0≦d≦0.40 and 0≦e≦0.60; and 
   corresponding to one of formula BaMgAl 10 O 17 ; Ba 0.9 Eu 0.1 MgAl 10 O 17 ; Ba 0.9 Eu 0.1 Mg 0.6 Mn 0.4 Al 10 O 17 ; Ba 0.9 Eu 0.1 Mg 0.8 Mn 0.2 Al 10 O 17 ; Ba 0.9 Eu 0.1 Mg 0.95 Mn 0.05 Al 10 O 17 ; BaMgAl 14 O 23 ; Ba 0.9 Eu 0.1 MgAl 14 O 23 ; or Ba 0.8 Eu 0.2 Mg 1.93 Mn 0.07 Al 16 O 27 .   
     
     
         6 . The modified phosphor according to  claim 1 , wherein the modified phosphor is in the form of particles, said particles having a mean diameter d 50  of at least 0.10 μm and of at most 1.00 μm. 
     
     
         7 . The modified phosphor according to  claim 1 , wherein the at least one amphiphilic agent is selected from the group consisting of the linear or branched, aliphatic or aromatic, acids having from 10 to 50 carbon atoms, optionally carrying functional groups, as well as their salts and derivatives. 
     
     
         8 . The modified phosphor according to  claim 1 , wherein the amphiphilic agent is selected from the group consisting of the linear or branched aliphatic carboxylic acids having from 10 to 40 carbon atoms and their salts. 
     
     
         9 . The modified phosphor according to  claim 1 , wherein the amphiphilic agent is stearic acid or isostearic and their isomers and salts thereof. 
     
     
         10 . The modified phosphor according to  claim 1 , wherein the at least one amphiphilic agent is least 0.1 wt % and at most 10.0 wt % with respect to the total weight of the phosphor particles. 
     
     
         11 . A process for the preparation of the modified phosphor of  claim 1 , the process comprising adding at least one amphiphilic agent to a composition of phosphor particles in a liquid medium; and removing the liquid medium. 
     
     
         12 . A composition comprising the modified phosphor of  claim 1  and at least one polymer. 
     
     
         13 . A composition according to  claim 12  wherein the particles of the modified phosphor are dispersed in the polymer. 
     
     
         14 . The composition according to  claim 12 , wherein the polymer is selected from the group consisting of the alpha-olefin homo- and copolymers, the polycondensation polymers such as polyamides, polyesters, polycarbonates, polyacrylates, and the halogenated polymers. 
     
     
         15 . The composition according to  claim 12 , wherein the polymer is a copolymer comprising copolymerized units of ethylene and of at least one carboxylic acid vinyl ester. 
     
     
         16 . The composition according to  claim 15  wherein the copolymer is crosslinked. 
     
     
         17 . The composition according to  claim 12 , wherein the modified phosphor is at least 0.05 wt % with respect to the total weight of the composition. 
     
     
         18 . The composition according to  claim 12 , wherein:
 the phosphor is selected from the group consisting of the aluminates doped with at least one rare earth element and/or manganese, the europium-doped phosphates or halophosphates, the europium- and/or manganese-doped silicates, the cerium-doped rare earths borates or silicates, the rare earth oxysulphurs, the rare earths vanadates, the zinc compounds doped with maganese, zinc, silver and/or copper;   the at least amphiphilic agent is stearic acid or isostearic and their isomers and salts thereof;   the polymer is a copolymer comprising copolymerized units of ethylene and of at least one carboxylic acid vinyl ester.   
     
     
         19 . A film comprising the composition of  claim 12 . 
     
     
         20 . The film according to  claim 19  with a thickness of 450 nm exhibiting a haze at 524 nm less than 35%, the haze being determined according to the following relationship: % haze 524 nm =total transmittance (%) 524 nm/diffuse transmittance 524 nm , the total transmittance and diffuse transmittance being recorded with a UV-VIS spectrometer over a range from 450 to 800 nm with a step of 1 nm. 
     
     
         21 . A film according to  claim 19  with a thickness of 450 nm exhibiting a total transmittance in the range 450-800 nm of more than 80%, the total transmittance being recorded with a UV-VIS spectrometer over a range from 450 to 800 nm with a step of 1 nm. 
     
     
         22 . A photovoltaic device comprising the composition of  claim 12 . 
     
     
         23 . A green-house comprising the composition of  claim 12 .