MULTI-LAYER FILM

Abstract

A multi-layer film for seal-peel applications, an article comprising said film and the use of said film a disclosed. The multi-layer film for seal-peel application comprising at least two layers, namely a cover layer and a seal layer, whereby the seal layer comprises between 25 and 80 wt. % of EVA and between 20 and 75 wt. % of LLDPE based on the total weight of the layer.

Claims

1. A multi-layer film for seal-peel application comprising at least two layers, namely a cover layer and a seal layer, whereby the seal layer comprises between 25 and 80 wt. % of EVA and between 20 and 75 wt. % of LLDPE based on the total weight of the seal layer.

2. The multi-layer film according to claim 1, wherein the LLDPE has a density between 0.850 and <0.945 g/cm.sup.3.

3. The multi-layer film according to claim 1, wherein the melt flow index of the LLDPE ranges from 0.3 to 15 g/10 min.

4. The multi-layer film according to claim 1, wherein the amount of LLDPE in the seal layer is between 20% and 75% by weight based on the total weight of the layer, by weight based on the total weight of the seal layer.

5. The multi-layer film according to claim 1, wherein the amount of EVA in the seal layer is between 25% and 80% by weight based on the total weight of the seal layer.

6. The multi-layer film according to claim 1, wherein the melt flow index of the EVA ranges from 1 to 35 g/10 min.

7. The multi-layer film according to claim 1, wherein the vinyl acetate content of the EVA is between 4 and 50 wt. %.

8. The multi-layer film according to claim 1, wherein the film comprises a first LDPE cover layer arranged on and in contact with the seal layer and a second cover layer of a blend of LLDPE and LDPE arranged on and in contact with the LDPE cover layer.

9. The multi-layer film according to claim 1, wherein the seal layer consists of between 25 and 80 wt. % of EVA and between 20 and 75 wt. % of LLDPE based on the total weight of the layer.

10. The multi-layer film according to claim 1, wherein when the EVA content of the seal layer is <50 wt. % the vinyl acetate content of the EVA is >20 wt. % or when the EVA content of the seal layer is >50 wt. % the vinyl acetate content of the EVA is <20 wt. %.

11. The multi-layer film according to claim 1, wherein the seal layer comprises only one LLDPE and/or not two or more different LLDPE's.

12. The multi-layer film according to claim 1, wherein seal layer is obtained by melt blending LLDPE and EVA at a temperature between 120 and 200 C.

13. The multi-layer film according to claim 1, wherein the film has a peel strength on PET of between 1 and 20 N/15 mm.

14. An article and/or packaging comprising the multi-layer film according to claim 1.

15. (canceled)

16. The multi-layer film according to claim 1, wherein the LLDPE has a density between 900 to 0.935 g/cm.sup.3, wherein the melt flow index of the LLDPE ranges from 1 to 10 g/10 min, wherein the amount of LLDPE in the seal layer is between 25% and 70% by weight based on the total weight of the seal layer, wherein the amount of EVA in the seal layer is between 30% and 75% by weight based on the total weight of the seal layer, wherein the melt flow index of the EVA ranges from 2 to 20 g/10 min, wherein the vinyl acetate content of the EVA is between 10 and 40 wt. %,

17. The multi-layer film according to claim 16, wherein the film comprises a first LDPE cover layer arranged on and in contact with the seal layer and a second cover layer of a blend of LLDPE and LDPE arranged on and in contact with the LDPE cover layer.

18. The multi-layer film according to claim 16, wherein the seal layer comprises only one LLDPE and/or not two or more different LLDPE's.

19. The multi-layer film according to claim 1, wherein the melt flow index of the LLDPE ranges from 2.5 to 3.5 g/10 min, wherein the amount of LLDPE in the seal layer is between 51 and 70% by weight based on the total weight of the seal layer, wherein the amount of EVA in the seal layer is between 30 and 49% by weight based on the total weight of the seal layer, wherein the melt flow index of the EVA ranges from 2 to 3 g/10 min or from 10 to 20 g/10 min, wherein the vinyl acetate content of the EVA is between 15 and 35 wt. %, and wherein the film has a peel strength on PET of between 1.5 and 15 N/15 mm.

Description

EXAMPLES

[0043] As shown in Table 1 below, the seal layer was compounded in a ZSK-26MC twin screw extruder from W&P. Maximum extrusion temperature was 170 and 160 C. for NT and LT conditions respectively. Similarly melt temperature was 175 C. and 162 C., screw speed was 300 rpm and 250 rpm again for NT and LT conditions respectively. Output was 15 kg/hour in both NT and LT conditions.

TABLE-US-00001 TABLE 1 Parameters UOM *NT *LT Feed (Zone 0) Temp C. 50 50 Zone 1 Temp C. 100 100 Zone 2 Temp C. 130 130 Zone 3 Temp C. 140 130 Zone 4 Temp C. 150 130 Zone 5 Temp C. 160 125 Zone 6 Temp C. 160 125 Zone 7 Temp C. 160 125 Zone 8 Temp C. 160 115 Zone 9 Temp C. 160 110 Zone 10 Temp C. 160 100 Die Temp C. 170 160 Screw speed rpm 300 250 Throughput kg/hr 15 15 Tmelt % 175 162

[0044] Normal temperature conditions (NT) and lower temperature conditions (LT) for the compounding are reported in Table 1 above.

[0045] Four different seal layers 1, 2, 3a and 3b were obtained with the compositions as presented in Table 2 below.

TABLE-US-00002 TABLE 2 EVA PE Compound EVA PE parameter No. Grade wt. % Grade wt. % MI Processing 1 ELVAX460 69 6318BE 31 2.65 NT 2 EVAFLEX 35 6318BE 65 7.2 NT EV250 3a EVAFLEX 44 6318BE 56 8.28 NT EV250 3b EVAFLEX 44 6318BE 56 8.28 LT EV250

[0046] As EVA, two Dupont grades ELVAX460 and EVAFLEX EV250 (Dupont-Mitsui) were used. As LLDPE SABIC grade 6318BE was used. Seal layer 3b has been produced using lower temperature (LT) compounding conditions as reported above in Table 1.

[0047] 3 layer films were produced on a Labtech, LF40000EX multilayer extrusion blow film machine as indicated below in Table 3, BUR was 2, die gap was 2.0, total thickness was 50 micron.

[0048] A second cover layer comprising 30 wt. % of low density polyethylene of SABIC grade 2201H0W and 70 wt. % of linear low density polyethylene of SABIC grade 6118NSF is arranged in contact with the first cover layer. A first cover layer of low density polyethylene of SABIC grade 2201H0W is arranged in contact with the seal layer.

[0049] The thicknesses of second cover layer, the first cover layer and the seal layer were 17.5 microns, 17.5 microns and 15 microns respectively. The extrusion temperatures for the second cover layer, the first cover layer and the seal layer were 210 C., 210 C. and 175 C., respectively.

TABLE-US-00003 TABLE 3 Layer information Profile Layer Pipe Adaptor Barrel 4 Barrel 3 Barrel 2 Barrel 1 (%) C. C. C. C. C. C. C. Second cover layer 35 210 210 210 210 210 190 170 First cover layer 35 210 210 210 210 210 190 170 Seal layer 30 210 175 175 175 175 175 125

[0050] After a corona treatment with a CTP-2000K Plasma generator provided on the 3 layer films, the 3 layers film above was laminated to a 15 micron biaxially oriented nylon film with an adhesive substance, namely Liofol LA2788, using a FM380 lamination machine from Simeile. The coating weight was 2.85 g/m2.

[0051] Table 4 shows the peel strength values in N/15 mm for different seal temperatures obtained with the 3 layer films above (see Table 3) with different seal layers 1, 2, 3a and 3b (see Table 2).

TABLE-US-00004 TABLE 4 peel strength values (N/15 mm) Seal temperature 80 C. 90 C. 110 C. 130 C. 150 C. Seal layer No. 1 1.99 1.76 6.43 8.11 10.86 Seal layer No. 2 0.79 3.68 4.50 3.50 4.92 Seal layer No. 3a 0.91 1.93 3.52 3.00 4.10 Seal layer No 3b 0.43 0.72 5.60 4.60 6.14

[0052] Peel strength has been measured according to ASTM F88 method C, after keeping under room temperature 72 hours, the film was sealed to a 250 micron PET film with a strip width of 15 mm by a HSG-C seal machine from Brugger. The standard testing condition was follow: dwell time was 1.5 second, pressure was 4 bar, width and length of sealing bar size was 10 mm*150 mm, sealing temperature was from 80 C. to 150 C., separation rate 200 mm/min.

TABLE-US-00005 TABLE 5 EVAs used VA content Grade Vendor MI (wt. %) density ELVAX460 Dupont 2.5 18 0.941 EVAFLEX Dupont-Mitsui 15 28 0.950 EV250