MULTI-LAYER FILM

Abstract

The present invention concerns a multi-layer film comprising at least five layers, with two outer layers, two intermediate layers and one core layer, wherein the core layer comprises an ethylene copolymer having a density between 0.910 g/cm3 and 0.925 g/cm3, the intermediate layers comprise an ethylene copolymer comprising 1-octene and having a density between >0.915 g/cm3 and 0.925 g/cm.sup.3, wherein further the first outer layer comprises between 65 wt. % and 93 wt. % of a first ethylene copolymer comprising 1-octene and having a density between >0.915 g/cm3 and 0.925 g/cm.sup.3 and between 7 wt. % and 35 wt. % of a second ethylene copolymer having a density between >0.925 g/cm.sup.3 and 0.945 g/cm3 based on the total weight of polymers of the layer, wherein further the second outer layer comprises between 35 wt. % and 65 wt. % of a first ethylene copolymer comprising 1-octene and having a density between >0.915 g/cm.sup.3 and 0.925 g/cm.sup.3 and between 35 wt. % and 65 wt. % of a second ethylene copolymer having a density between 0.850 g/cm.sup.3 and <0.915 g/cm.sup.3 based on the total weight of the polymers of the layer.

Claims

1. Multi-layer film comprising at least five layers, with two outer layers, two intermediate layers and one core layer, wherein the core layer comprises an ethylene copolymer having a density between >0.910 g/cm.sup.3 and 0.925 g/cm.sup.3, wherein the intermediate layers comprise an ethylene copolymer comprising 1-octene and having a density between 0.910 g/cm.sup.3 and 0.925 g/cm.sup.3, wherein the first outer layer comprises either a polyethylene with a density between 0.915 g/cm.sup.3 and 0.935 g/cm.sup.3, or between 65 wt. % and 93 wt. % of a first ethylene copolymer comprising 1-octene and having a density between >0.915 g/cm.sup.3 and 0.925 g/cm.sup.3 and between 7 wt. % and 35 wt. % of a second ethylene copolymer having a density between >0.925 g/cm.sup.3 and 0.945 g/cm.sup.3, based on the total weight of polymers of the first outer layer, wherein the second outer layer comprises between 35 wt. % and 65 wt. % of a first ethylene copolymer comprising 1-octene and having a density between 0.910 g/cm.sup.3 and between 35 wt. % and 65 wt. % of a second ethylene copolymer having a density between 0.850 g/cm.sup.3 and <0.915 g/cm.sup.3, based on the total weight of the polymers of the second outer layer, and wherein each of the five layers comprises only polyolefins as polymers.

2. The multi-layer film according to claim 1, wherein the first outer layer comprises between 70 wt. % and <93 wt. % of the first ethylene copolymer comprising 1-octene and between >7 wt. % and 30 wt. % of the second ethylene copolymer based on the total weight of polymers of the first outer layer, and/or wherein the second outer layer comprises between 40 wt. % and 60 wt. % of the first ethylene copolymer comprising 1-octene and between 40 wt. % and 60 wt. % of the second ethylene copolymer based on the total weight of the polymers of the layer-second outer layer, and/or wherein the core layer comprises between 90 wt. % and 100 wt. % of the ethylene copolymer based on the total weight of the polymers of the core layer, and/or wherein each intermediate layer comprises between 90 wt. % and 100 wt. % of the ethylene copolymer based on the total weight of the polymers of the intermediate layer.

3. The multi-layer film according to claim 1, wherein the multi-layer film consists of five layers, and/or wherein the first outer layer and the second outer layer comprise the same first ethylene copolymer, and/or wherein the melt flow rate of the ethylene copolymer of the core layer is lower than the melt flow rate of the ethylene copolymer(s) of each of the intermediate layers, and/or wherein the multi-layer film comprises no polypropylene, and/or wherein the five layers are adjacent to each other.

4. The multi-layer film according to claim 1, wherein the ethylene copolymer of the core layer comprises 1-hexene or 1-octene.

5. The multi-layer film according to claim 1, wherein the second ethylene copolymer of the first outer layer comprises 1-hexene or 1-octene.

6. The multi-layer film according to claim 1, wherein the second ethylene copolymer of the second outer layer comprises 1-hexene or 1-octene.

7. The multi-layer film according to claim 1, wherein the density of the ethylene copolymer of the core layer is between 0.913 and 0.923 g/cm.sup.3, and/or the melt flow rate of the ethylene copolymer of the core layer is between 0.2 and 2.5 g/10 min.

8. The multi-layer film according to claim 1, wherein the density of the ethylene copolymer of the intermediate layer is between 916 g/cm.sup.3 and 0.923 g/cm.sup.3, and/or the melt flow rate of the ethylene copolymer of the intermediate layer is between 0.2 and 2.5 g/10 min.

9. The multi-layer film according to claim 1, wherein the density of the first ethylene copolymer of the first outer layer is between 916 g/cm.sup.3 and 0.923 g/cm.sup.3, and/or the melt flow rate of the ethylene copolymer of the intermediate layer is between 0.2 and 2.5 g/10 min.

10. The multi-layer film according to claim 1, wherein the density of the first ethylene copolymer of the second outer layer is between 916 g/cm.sup.3 and 0.923 g/cm.sup.3, and/or the melt flow rate of the first ethylene copolymer of the second outer layer is between 1 and 4 g/10 min.

11. The multi-layer film according to claim 1, wherein the density of the second ethylene copolymer of the first outer layer is between 0.930 g/cm.sup.3 and 0.940 g/cm.sup.3, and/or the melt flow rate of the ethylene copolymer of the second ethylene copolymer of the first outer layer is between 1 and 4 g/10 min.

12. The multi-layer film according to claim 1, wherein the density of the second ethylene copolymer of the second outer layer is between 0.855 g/cm.sup.3 and 0.910 g/cm.sup.3, and/or the melt flow rate of the ethylene copolymer of the second ethylene copolymer of the first second outer layer is between 0.2 and 2.5 g/10 min.

13. The multi-layer film according to claim 1, wherein the thickness of each outer layer represents between 10% and 20% of a total film thickness, and/or the thickness of each intermediate layer represents between 15% and 25% of the total film thickness, and/or the thickness of the core layer represents between 25% and 35% of the total film thickness.

14. Silage comprising the multi-layer film according to claim 1.

15. (canceled)

16. The multi-layer film of claim 1, comprising at least five layers, wherein the density of the intermediate layers between >0.915 g/cm.sup.3 and 0.925 g/cm.sup.3, wherein the polyethylene of the first outer layer is a low density polyethylene with a density between 0.915 g/cm.sup.3 and 0.935 g/cm.sup.3, wherein the first ethylene copolymer of the second outer layer has a density between >0.915 g/cm.sup.3 and 0.925 g/cm.sup.3, and wherein the multi-layer film comprises only polyolefins as polymers.

17. The multi-layer film of claim 1, comprising at least five layers, wherein the density of the intermediate layers between >0.915 g/cm.sup.3 and 0.925 g/cm.sup.3, wherein the first outer layer comprises between 65 wt. % and 93 wt. % of a first ethylene copolymer comprising 1-octene and having a density between >0.915 g/cm.sup.3 and 0.925 g/cm.sup.3 and between 7 wt. % and 35 wt. % of a second ethylene copolymer having a density between >0.925 g/cm.sup.3 and 0.945 g/cm.sup.3, based on the total weight of polymers of the first outer layer, and wherein the multi-layer film comprises only polyolefins as polymers.

18. Multi-layer film according to claim 1, wherein the first outer layer comprises between >75 wt. % and <90 wt. % of the first ethylene copolymer comprising 1-octene and between >10 wt. % and <25 wt. % of the second ethylene copolymer, based on the total weight of polymers of the first outer layer, and/or wherein the second outer layer comprises between >40 wt. % and <60 wt. % of the first ethylene copolymer comprising 1-octene and between >40 wt. % and <60 wt. % of the second ethylene copolymer, based on the total weight of the polymers of the second outer layer.

19. Multi-layer film according to claim 1, wherein the melt flow rate of the ethylene copolymer of the core layer is lower than the melt flow rate of the ethylene copolymer(s) of each of the intermediate layers.

20. The multi-layer film according to claim 1, wherein the multi-layer film comprises no polypropylene.

21. The multi-layer film according to claim 1, wherein the density of the ethylene copolymer of the core layer is between >0.915 and <0.923 g/cm.sup.3, and the melt flow rate of the ethylene copolymer of the core layer is between 0.5 and 1.5 g/10 min, wherein the density of the ethylene copolymer of the intermediate layer is between >0.916 g/cm.sup.3 and <0.923 g/cm.sup.3, and the melt flow rate of the ethylene copolymer of the intermediate layer is between 0.5 and 1.5 g/10 min, wherein the density of the first ethylene copolymer of the first outer layer is between >0.916 g/cm.sup.3 and <0.923 g/cm.sup.3, and the melt flow rate of the ethylene copolymer of the intermediate layer is 0.5 and 1.5 g/10 min, wherein the density of the second ethylene copolymer of the first outer layer is between >0.930 g/cm.sup.3 and <0.940 g/cm.sup.3, and the melt flow rate of the second ethylene copolymer of the first outer layer is between 2.4 and <3.5 g/10 min, wherein the density of the first ethylene copolymer of the second outer layer is between >0.916 g/cm.sup.3 and <0.923 g/cm.sup.3, and wherein the melt flow rate of the first ethylene copolymer of the second outer layer is between 2.5 and 3.5 g/10 min, and wherein the density of the second ethylene copolymer of the second outer layer is between >0.860 g/cm.sup.3 and <0.890 g/cm.sup.3, and the melt flow rate of the second ethylene copolymer of the second outer layer is between 0.5 and 1.5 g/10 min.

Description

EXAMPLES

[0053] Films according to the invention have been produced on a 5-layer co-extrusion blown line as described below.

Line Descriptions and Process Settings:

[0054]

TABLE-US-00001 Five extruders five layers Target thickness 25 m; BUR 2.5 Die gap = 2.4 mm; 550 mm Dual ring Double flow air ring. Contactless type. Air cooling temperature 15 C. Ring 52% of total power IBC 60% power Line speed 61 m/min Output 352 kg/h

[0055] The extruder settings, extruder temperature profiles and die temperature profile were thereby as described below (see Tables 1, 2 and 3).

TABLE-US-00002 TABLE 1 Extruder settings Pressure IN Pressure OUT Melt Speed rpm Torque % Bar Bar C. Extr. A 54.3 19 83 63 215 Extr. B 55.2 54 182 134 217 Extr. C 23 41 138 97 213 Extr. D 58 49 170 120 214 Extr. E 87.6 44 165 112 213

TABLE-US-00003 TABLE 2 Temperature profiles (C.) Extruder Extruder Extruder A Extruder B C Extruder D E Zone 1 40 40 40 40 40 Zone 2 210 210 210 210 210 Zone 3 210 210 210 210 210 Zone 4 210 210 210 210 210 Zone 5 210 Filter 1 210 210 210 210 210 Filter 2 210 210 210 210 210 Filter 3 210 210 210 210 210

TABLE-US-00004 TABLE 3 Die temperature profile (C. ) zone zone zone zone zone zone zone zone zone Zone zone Zone zone A1 A2 A3 B C D E F G I H L M 215 215 215 210 210 210 210 210 210 210 210 210 210

[0056] The layer compositions of the multi-layer films according the invention (samples A1 and A2) are as described below (see Table 4).

TABLE-US-00005 TABLE 4 Muli-laver films according to the sample A1 sample A2 film extruder (composition of (composition of thickness (%) laver layer in wt. %) layer in wt. %) 10% A 100% LDPE 100% LDPE 25% B 100% SUPEER 8115 100% SUPEER 8115 30% C 100% SUPEER 8115 100% SUPEER 8115 25% D 100% SUPEER 8115 100% SUPEER 8115 10% E 70% COHERE 8570 + 50% COHERE 8570 + 30% SUPEER 8115 50% SUPEER 8115 LDPE 2501 is commercialy available from SABIC and is an LDPE with a density of 0.925 g/cm3 and an MFR of 0.75 g/10 min. SUPEER 8115 is commercialy available from SABIC and is a copolymer of ethylene and 1-octene with a density of 0.915 g/cm3 and an MFR of 1.1 g/10 min. COHERE 8570 is commercialy available from SABIC and is a copolymer of ethylene and 1-octene with a density of 0.868 g/cm3 and an MFR of 5 g/10 min

[0057] A comparative example of a silage film has been produced on a 5-layer co-extrusion blown line as described below.

Line Descriptions and Process Settings:

[0058]

TABLE-US-00006 Five extruders five layers Target thickness 25 m; BUR 2.4 Die gap = 2.4 mm; 400 mm Air cooling temperature 15 C. Ring 51% of total power IBC 46% power Line speed 55 m/min Output 240 kg/h

[0059] The extruder settings, extruder temperature profiles and die temperature profile were thereby as described below (see Tables 5, 6 and 7).

TABLE-US-00007 TABLE 5 Extruder settings Kg/h Kg/h % Speed rpm Torque % Pressure Bar Melt C. Extr. A 36 15 40 14 196 221 Extr. B 47 20 53 21 196 219 Extr. C 73 30 22 45 224 218 Extr. D 48 20 53 20 181 216 Extr. E 36 15 42 13 180 223

TABLE-US-00008 TABLE 6 Temperature profiles (C.) Extruder Extruder A Extruder B C Extruder D Extruder E Zone 1 40 40 40 44 40 Zone 2 199 186 210 187 198 Zone 3 210 210 210 210 210 Zone 4 210 210 210 210 210 Zone 5 210 210 210 210 210 Zone 6 210 210 210 210 210 Zone 7 210 210 210 210 210 Zone 8 210 210

TABLE-US-00009 TABLE 7 Die temperature profile (C.) zone 1 zone 2 zone 3 zone 4 zone 5 zone 6 210 210 210 210 220 220

[0060] The composition of the multi-layer films according to comparative example (A3) with respect to polymers is as described below (Table 8).

TABLE-US-00010 TABLE 8 Comparative example film thickness extruder/ (%) layer sample A3 15% A 91% Escorene Ultra FL 00218 + 9% PIB 20% B 75% Exceed 2018 HA + 16% Enable 2703 HH + 9% PIB 30% C 75% Exceed 2018 HA + 16% Enable 2703 HH + 9% PIB 20% D 75% Exceed 2018 HA + 16% Enable 2703 HH + 9% PIB 15% E 93% Exceed 1018 HA + 7% PIB

[0061] PIB is a polyisobutylene TAC100 masterbatch commercially available from A. SCHULMAN Inc.

[0062] Exceed 2018 HA is commercially available from ExxonMobil and is a copolymer of ethylene and 1-hexene with a density of 0.918 g/cm3 and an MFR of 2 g/10 min.

[0063] Exceed 1018 HA is commercially available from ExxonMobil and is a copolymer of ethylene and 1-hexene with a density of 0.918 g/cm3 and an MFR of 1 g/10 min.

[0064] Enable 2703 HH is commercially available from ExxonMobil and is a copolymer of ethylene and 1-hexene with a density of 0.927 g/cm3 and an MFR of 0.3 g/10 min.

[0065] Escorene Ultra FL 00218 is commercially available from ExxonMobil and is a copolymer of ethylene and vinyl-acetate with a density of 0.940 g/cm3 and an MFR of 1.7 g/10 min.

[0066] Based on measurements complying with ASTM D5458, one can see that the average peel cling force is higher for multi-layer films according to the invention (samples A1 and A2) compared to the comparative example A3 both in unstretched state (0% pre-stretch) and at 100% pre-stretch (see values reported below, Table 9).

TABLE-US-00011 TABLE 9 TABLE OF ADHESION MEASUREMENTS Unit sample A1 sample A2 sample A3 Thickness average m 24 26 23 Thickness st. dev. m 1 1 1 Peelcling ASTM D5458 23 C./50% RH/pre stretch 0% Peel cling force average N 3.57 3.10 3.00 Peel cling force st. dev. N 0.12 0.14 0.20 Peel cling average N/mm 0.15 0.13 0.12 Peel cling st. dev. N/mm 0.01 0.01 0.01 Number of specimens 5 5 3 Peelcling ASTM D5458 23 C./50% RH/pre stretch 100% Peel cling force average N 2.89 2.24 2.21 Peel cling force st. dev. N 0.10 0.11 0.19 Peel cling average N/mm 0.12 0.09 0.09 Peel cling st. dev. N/mm 0.00 0.00 0.01 Number of specimens 5 5 3