1. A process for preparing a bead of a flame-retardant expandable vinyl aromatic polymer, the process comprising:
polymerizing a vinyl aromatic monomer in aqueous suspension, and
adding an expanding agent before, during, or after the polymerizing,
wherein the process is carried out with a system consisting of water the vinyl aromatic monomer, a peroxide initiator, an amide, a flame-retardant, and optionally the expanding agent;
wherein the amide has formula (I):
R1CONHCH2\u2014CH2NHCOR2\u2003\u2003(I);
wherein R1 and R2 are each independently an (iso)alkyl radical CH3(CH2)n, a C6-C12 aromatic radical, or a C7-C25 alkylaromatic radical; if either or both of R1 and R2 is an (iso)alkyl radical CH3(CH2)n, each n is independently from 10 to 20;
wherein the flame-retardant is a brominated additive optionally with a synergic agent comprising a C\u2014C or C\u2014O\u2014O\u2014C thermolabile bond, wherein the brominated additive has a bromine content higher than 30% by weight;
wherein the bead is capable of producing an expanded article with a reduced thermal conductivity; and
wherein the peroxide initiator is active at a temperature higher than 80\xb0 C.
2. The process of claim 1, wherein a content of the amide is 5 to 5,000 ppm, with respect to a weight of the vinyl aromatic monomer.
3. The process of claim 1, wherein the amide is N,N\u2032-ethylene-bis-stearamide.
4. The process of claim 1, wherein the expanding agent is at least one expanding agent selected from the group consisting of an aliphatic or cyclo-aliphatic hydrocarbon having from 3 to 6 carbon atoms; a halogenated derivative of an aliphatic hydrocarbon having from 1 to 3 carbon atoms; carbon dioxide; and ethyl alcohol.
5. The process of claim 1, wherein a content of the expanding agent is from 1 to 10% by weight, with respect to a weight of the vinyl aromatic monomer.
6. The process of claim 1, wherein the flame-retardant is an aliphatic, cyclo-aliphatic, brominated aromatic compound with a bromine content higher than 30% by weight.
7. The process of claim 1, wherein a content of the flame-retardant is from 0.1 to 3% by weight, with respect to a weight of the vinyl aromatic monomer.
8. The process of claim 1, wherein the flame-retardant is the brominated additive with the synergic agent comprising a C\u2014C or C\u2014O\u2014O\u2014C thermolabile bond.
9. The process of claim 8, wherein a content of the synergic agent is from 0.01% to 1% by weight, with respect to a weight of the vinyl aromatic monomer.
10. The process of claim 1, wherein the vinyl aromatic monomer is styrene or a mixture of styrene comprising up to 25% by weight of \u03b1-methylstyrene.
11. The process of claim 1, wherein, in formula (I):
R1, R2, or both are an (iso)alkyl radical CH3(CH2)n, and
each n is independently from 16 to 18.
12. The process of claim 1, wherein the bead is capable of producing an expanded article with a density of from 5 to 50 gL and a thermal conductivity of from 25 to 50 mWmK.
13. The process of claim 2, wherein the content of the amide is from 10 to 500 ppm, with respect to a weight of the vinyl aromatic monomer.
14. The process of claim 1, wherein the vinyl aromatic monomer comprises a monomer of formula (II):
wherein
R is hydrogen or a methyl group,
n is an integer of from zero to 5, and
each Y, if Y is present, is independently a halogen or an alkyl or alkoxyl radical having from 1 to 4 carbon atoms.
15. The process of claim 1, wherein adding the expanding agent is during the polymerizing.
16. A process for preparing a bead of a flame-retardant expandable vinyl aromatic polymer, the process comprising:
polymerizing a vinyl aromatic monomer in aqueous suspension, and
adding an expanding agent before, during, or after the polymerizing,
wherein the process is carried out with a system consisting of water, the vinyl aromatic monomer, a peroxide initiator, an amide, a flame-retardant, and optionally the expanding agent;
wherein the amide has formula (I):
R1CONHCH2\u2014CH2NHCOR2\u2003\u2003(I);
wherein R1 and R2 are each independently an (iso)alkyl radical CH3(CH2)n, a C6-C12 aromatic radical, or a C7-C25 alkylaromatic radical; if either or both of R1 and R2 is an (iso)alkyl radical CH3(CH2)n, each n is independently from 10 to 20;
wherein the flame-retardant is a brominated additive with a synergic agent comprising a C\u2014C or C\u2014O\u2014O\u2014C thermolabile bond, wherein the brominated additive has a bromine content higher than 30% by weight;
wherein the bead is capable of producing an expanded article with a reduced thermal conductivity; and
wherein the peroxide initiator is active at a temperature higher than 80\xb0 C.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An organic electroluminescent display apparatus, comprising:
red organic electroluminescent devices;
green organic electroluminescent devices; and
blue organic electroluminescent devices,
each of the electroluminescent devices serving as a pixel and having a pair of electrodes, a hole transport layer, and an emission layer,
wherein:
the emission layer of each of the green organic electroluminescent devices has a delayed fluorescent material;
each of the green organic electroluminescent devices has a microcavity between the pair of electrodes; and
the hole transport layers of the green organic electroluminescent devices and the blue organic electroluminescent devices are provided so that the layers have the same thickness and are common to the devices.
2. The organic electroluminescent display apparatus according to claim 1, wherein a layer having a largest thickness out of the layers interposed between the pair of electrodes of each of the green organic electroluminescent devices comprises the emission layer.