Mineral filled polyethylene for inner liners
View Patent ↗Inner liners of foam insulated refrigerators and freezers are made of mineral filled bimodal polyethylene.
1. Inner liners of foam insulated refrigerators and freezers, comprising mineral filled bimodal polyethylene, wherein the content of the mineral filler is from 20 wt % to 60 wt %, relative to the weight of the bimodal polyethylene.
2. Inner liners according to claim 1 , wherein the bimodal polyethylene has a weight average molecular weight M w of from 90,000 to 450,000 g/mol, a molecular weight distribution M w /M n of from 5 to 40, a melt flow rate MFR 2 of from 0.05 to 4.0 g/10 mm, a melt flow rate MFR 21 of from 7 to 200 g/10 mm, a flow ratio FFR 21/2 of from 40 to 180, and a density of from 912 to 960 kg/m 3 .
3. Inner liners according to claim 1 , wherein the bimodal polyethylene comprises (in) from 30 to 70 wt %, based on the weight of the bimodal polyethylene, of a low molecular weight component having a MFR 2 of from 10 to 1,000 g/10 min, and a density higher than 930 kg/m 3 , and (ii) from 70 to 30 wt %, based on the weight of the bimodal polyethylene, of a high molecular weight component which is a polyethylene copolymer having such a molecular weight and comonomer content that at a given split of the components, the bimodal polyethylene has the desired melt index and density.
4. Inner liners according to claim 3 , wherein the low molecular weight component is a polyethylene homopolymer having a melt flow rate MFR 2 of from 100 to 500 g/10 min, and a density higher than 965 kg/m 3 .
5. Inner liners according to claim 3 , wherein the low molecular weight component is a polyethylene copolymer having a MFR 2 of from 10 to 1000 g/10 min.
6. Inner liners according to claim 3 or claim 5 , wherein the C 3 -C 8 alpha-olefin as the comonomer.
7. Inner liners according to claim 6 , wherein the C 3 -C 8 alpha-olefin comonomer is present in an amount of 0.5 wt % to 20 wt %, based on the weight of the bimodal polyethylene.
8. Inner liners according to claim 3 or claim 5 , wherein the polyethylene copolymer comprises 1-butene as the comonomer.
9. Inner liners according to claim 1 , wherein the mineral filler comprises at least one selected from the group consisting of kaolin, wollastonite, magnesium hydroxide, chalk, different clays, talcum, silica, barium sulphate, mica and mixtures thereof.
10. Inner liners according to claim 1 , wherein the mineral filler comprises talcum or chalk.
11. Inner liners according to claim 1 , wherein the content of mineral fillers is 30 to 50 wt %, based on the weight of the mineral filled bimodal polyethylene.