Peroxide blends for cross-linking ethylene vinyl acetate in an accelerated manner
The present invention relates to peroxide mixtures and in particular to peroxide mixtures that are suitable for the accelerated crosslinking of ethylene vinyl acetate.
1. A peroxide mixture comprising: 3-30 wt % of t-butyl-per-2-ethylhexanoate (TBPEH); and 70-97 wt % of tert-butylperoxy(2-ethylhexyl)carbonate (TBPEHC) based on the total weight of the peroxide mixture.
2. A method of crosslinking polymers comprising using the peroxide mixture of claim 1 to crosslink polymers.
3. The method of claim 2 , wherein the polymer is ethylene vinyl acetate.
4. The method of claim 2 , wherein the polymer is ethylene vinyl acetate;
crosslinking the ethylene vinyl acetate to form a film, and,
encapsulating a solar cell wafer with the film.
5. The method of claim 2 , wherein the crosslinking takes place at a temperature in the range of from 120° C. to 150° C.
6. A process for the production of a crosslinked polymer, comprising:
(i) mixing the peroxide mixture of claim 1 with a crosslinkable polymer;
(ii) shaping the mixture of crosslinkable polymer and peroxides; and,
(iii) increasing the temperature of the mixture in order to bring about crosslinking of the shaped polymer.
7. The process of claim 6 , wherein the peroxide mixture is added in the form of a masterbatch with an amount by weight of from 0.5 wt. % to 75 wt. % to the crosslinkable polymer, in particular to a crosslinkable ethylene vinyl acetate.
8. The process of claim 6 , wherein step (ii) is carried out in a shaping machine, in particular in a film extrusion system.
9. The process of claim 6 , wherein the amount of added peroxide mixture of claim 1 , based on the polymer, is from 0.1 to 5 wt. %.
10. A premixture comprising:
(a) the peroxide mixture of claim 1 ; and,
(b) a crosslinkable polymer.
11. The premixture of claim 10 , wherein the premixture is present in granulate or/and powder form.
12. The premixture of claim 10 in the form of a masterbatch, wherein the content of peroxides is from 0.5 wt.% to 75 wt.%, based on the total weight of the premixture.
13. The premixture of claim 10 , wherein the crosslinkable polymer is an ethylene vinyl acetate.
14. The process of claim 1 , wherein the crosslinkable polymer is a crosslinkable ethylene vinyl acetate.