POLYETHYLENE SEALANT FILM WITH LOW FRICTION CONTAINING RECYCLED POLYMER

Abstract

The invention relates to a polyethylene sealant film comprising an outer layer O, a core layer C and an inner layer I, wherein the core layer C is made of a core layer composition comprising a component AC, which is a recycled low density ethylene polymer in an amount of at least 50 wt. %, based on the total weight of the core layer composition, and a slip agent; and the inner layer I is made of an inner layer composition comprising a component AI, which is a linear low density ethylene polymer having a density of from 910 to 925 kg/m.sup.3 and an MFR.sub.2 of from 0.5 to 2.0 g/10 min. determined according to ISO 1133. The invention further relates to a laminated polyethylene film and article comprising this polyethylene sealant film. The invention further relates to the use of the laminated polyethylene film and/or the polyethylene sealant film for packaging of an article.

Claims

1. A polyethylene sealant film comprising an outer layer O, a core layer C and an inner layer I, wherein a) the core layer C is made of a core layer composition comprising a component AC, which is a recycled low density ethylene polymer in an amount of at least 50 wt. %, based on the total weight of the core layer composition, and a slip agent; and b) the inner layer I is made of an inner layer composition comprising a component AI, which is a linear low density ethylene polymer having a density of from 910 to 925 kg/m.sup.3 and an MFR.sub.2 of from 0.5 to 2.0 g/10 min, determined according to ISO 1133.

2. The polyethylene sealant film according to claim 1, wherein the component AI is an ethylene copolymer having a density of from 916 to 920 kg/m.sup.3 and an MFR.sub.2 of from 1.2 to 1.8 g/10 min, determined according to ISO 1133.

3. The polyethylene sealant film according to claim 1, wherein the inner layer composition further comprises a component BI, which is an ethylene-based plastomer.

4. The polyethylene sealant film according to claim 1, wherein the inner layer composition comprises a slip agent in an amount of from 50 to 5000 ppm, and/or an anti-block agent in an amount of from 50 to 5000 ppm, each being based on the total weight of the inner layer composition.

5. The polyethylene sealant film according to claim 1, wherein the slip agent comprises a compound selected from the group consisting of fatty acid amides, such as erucamide, oleamide or stearamide, and combinations thereof; and/or the anti-block agent comprises a compound selected from the group consisting of inorganic compounds such as talc, kaolin, cristobalite, natural silica and synthetic silica, diatomaceous earth, mica, calcium carbonate, calcium sulfate, magnesium carbonate, magnesium sulfate, and feldspars, and combinations thereof.

6. The polyethylene sealant film according to claim 1, wherein the component AC has an MFR.sub.2 of from 0.25 to 1.0 g/10 min, determined according to ISO 1133, and/or a density of from 910 to 940 kg/m.sup.3.

7. The polyethylene sealant film according to claim 1, wherein the core layer composition further comprises a component BC, which is a linear low density ethylene polymer having an MFR.sub.5 of from 0.5 to 5 g/10 min, determined according to ISO 1133, and a density of from 920 to 940 kg/m.sup.3.

8. The polyethylene sealant film according to claim 1, wherein the core layer composition comprises from 50 to 5000 ppm of the slip agent, based on the total weight of the core layer composition.

9. The polyethylene sealant film according to claim 1, wherein the inner layer composition comprises from 20 to 60 wt. % of the component AI, and optionally from 40 to 80 wt. % of the component BI, each being based on the total weight of the inner layer composition.

10. The polyethylene sealant film according to claim 1, wherein the outer layer O is made of an outer layer composition, which is different from the inner layer composition.

11. The polyethylene sealant film according to claim 1, wherein the polyethylene sealant film has a dynamic coefficient of friction after 7 days of up to 0.30, determined according to ASTM D1894, and/or a seal initiation temperature (5 N) of less than 90 C., determined according to ASTM F 2029; ASTM F 88.

12. A laminated polyethylene film comprising the polyethylene sealant film according to claim 1 and a substrate film.

13. The laminated polyethylene film according to claim 12, wherein the laminated polyethylene film has a dynamic coefficient of friction after 4 days of up to 0.30, determined according to ASTM D1894.

14. An article comprising the polyethylene sealant film according to claim 1.

15. A method of using the polyethylene sealant film according to claim 1, comprising packaging an article using the polyethylene sealant film.

16. The polyethylene sealant film according to claim 2, wherein the component AI is a multimodal ethylene terpolymer having a density of from 916 to 920 kg/m.sup.3 and an MFR.sub.2 of from 1.2 to 1.8 g/10 min, determined according to ISO 1133.

17. The polyethylene sealant film according to claim 3, wherein the component BI is a copolymer of ethylene and a C3 to C10 alpha-olefin having an MFR.sub.2 of from 0.5 to 2.0 g/10 min, determined according to ISO 1133, and/or a density of from 880 to 912 kg/m.sup.3.

18. The polyethylene sealant film according to claim 7, wherein the component BC is a multimodal ethylene terpolymer.

19. The polyethylene sealant film according to claim 7, wherein the component BC is present in an amount of from 10 to 50 wt %, based on the total weight of the core layer composition.

20. The polyethylene sealant film according to claim 9, wherein the inner layer composition further comprises from 100 to 3000 ppm of the slip agent and from 200 to 4000 ppm of the anti-block agent, each being based on the total weight of the inner layer composition.

Description

EXAMPLES

Sealant Films

[0212] Two comparative examples (CE1 and CE2) and two inventive examples (IE1 and IE2) have been prepared as sealant films with a thickness of 60 m. The details of the films are summarized in Table 1, whereas the key properties of the polymers used are listed in Table 2. The external layers each make up 20% and the core layer makes up 60% of the total film thickness.

TABLE-US-00001 TABLE 1 Sealant film formulations (in wt. %). Outer layer O Core layer C Inner layer I Example 20% 60% 20% CE1 80% FK1828 30% FX1002 80% FX1001 20% FT6236 70% NAV101 20% FK1820 CE2 80% FK1828 100% NAV 101 80% FX1001 20% FT6236 20% FK1820 IE1 90% FK1820 29% FX1002 38% FK1828 10% FT5236 70% NAV101 60% 0201FX 1% slip agent 1% slip agent 1% AB IE2 90% FK1820 29% FX1002 38% FK1828 10% FT5236 70% CWT 100 LG 60% 0201FX 1% slip agent 1% slip agent 1% AB AB = Amide antiblock agent Polybatch FSU-105-E; Slip agent: 5% erucamide slip concentrate based in polyethylene, Polybatch CE505E (A. Schulman)

TABLE-US-00002 TABLE 2 Characteristics of the polymers used. Melting Resin MFR Density point name Producer Type (g/10 min) (kg/m.sup.3) ( C.) Anteo Borouge bimodal 1.5 918 122 FK1820 LLDPE terpolymer Anteo Borouge bimodal 1.5 918 122 FK1828 LLDPE terpolymer LDPE Borealis/ tubular LDPE 0.75 923 112 FT5236 Borouge LDPE Borealis/ tubular LDPE 2 923 110 FT6236 Borouge Borshape Borealis bimodal ethylene 0.9* 931 127 FX1001 terpolymer Borshape Borealis bimodal ethylene 2* 937 128 FX1002 terpolymer NAV 101 Borealis LDPE post- 0.5 920 122 consumer recyclate CWT 100 Borealis LDPE post- 0.6 925-929 100-140 LG consumer recyclate Queo Borealis Ethylene- 1.1 902 95 0201FX based octene-1 plastomer MFR = MFR.sub.2 (190 C./2.16 kg) except for * MFR = MFR.sub.5 (190 C./5 kg).

[0213] Processibility and film properties were evaluated on large scale blown film equipment. The 3-layer blown films were produced using an Alpine-make blown film line, the films having an O/C/I structure with the layers as shown in Table 1. Performance of the films was analyzed from 60-m blown films produced at the below process operating conditions with die-gap of 1.8 mm, lower neck-height and blow up ratio of 2.2:1. The blown film line had the following properties as follows in Table 3.

TABLE-US-00003 TABLE 3 Blown film line parameters. Die diameters 300 mm Die gap 1.8 mm Blow up ratio (BUR) 2.2:1 Bubble cooling internal bubble cooling (IBC) Cooling air temperature 22 C. Corona treatment outside layer 48 dyne/cm

[0214] The temperature profiles of the blown film extruders line i.e., the temperatures used for different locations of the blown film lines were as follows in Table 4.

TABLE-US-00004 TABLE 4 Blown film extruders production temperatures in C. Post Post Extruder Extruder Extruder Extruder Extruder Extruder Extruder Extruder Layer zone 1 zone 2 zone 3 zone 4 zone 5 zone 6 zone 7 zone 8 CE1 Outer layer (O) 190 190 190 190 190 200 200 Core layer (C) 40 200 200 200 200 210 210 210 Inner layer (I) 190 190 190 190 190 200 200 CE2 Outer layer (O) 190 190 190 190 190 200 200 Core layer (C) 40 200 200 200 200 210 210 210 Inner layer (I) 190 190 190 190 190 200 200 IE1 Outer layer (O) 190 190 190 190 190 200 200 Core layer (C) 40 200 200 200 200 210 210 210 Inner layer (I) 190 190 190 190 190 200 200 IE2 Outer layer (O) 190 190 190 190 190 200 200 Core layer (C) 40 190 190 190 190 210 210 210 Inner layer (I) 200 200 200 200 200 210 210

[0215] The films were evaluated for their properties by measuring the coefficient of friction and the seal initiation temperature (5 N). The results are summarized in Table 5. Accordingly, all parameters were improved in the inventive examples when compared to the comparative examples.

TABLE-US-00005 TABLE 5 Sealant film properties. Properties CE1 CE2 IE1 IE2 dynamic CoF 0.64 0.79 0.1 0.11 1 day static CoF 0.69 0.83 0.14 0.15 1 day dynamic CoF 0.51 0.58 0.1 0.11 7 days static CoF 0.56 0.62 0.15 0.16 7 days Seal initiation 96 95 80 79 temperature ( C.)

Laminates

[0216] After extrusion, the films were laminated to a 21.5 m MDO PE films. The films were laminated at Henkel Corporation using adhesive LA7825 and hardener LA6230 (both supplied by Henkel), mixed at a 2:1 ratio. Lamination was done on a solvent-less laminator at a running speed of 150 m/min with an adhesive content of 1.8 g/m.sup.2. The corona treatment intensity on the carrier web was 2.5 KW and on the secondary web 1.5 KW. Laminated films (Table 6, wherein e.g. CE1 is a laminated film comprising the CE1 sealant film etc.) with a thickness of about 80-90 m were prepared. Properties of the laminates were evaluated and are depicted below.

TABLE-US-00006 TABLE 6 Laminate properties. Properties CE1 CE2 IE1 IE2 dynamic CoF > 0.30 0.31 0.26 0.23 96 h inside- inside static CoF > 0.34 0.33 0.28 0.22 96 h inside- inside dynamic CoF > 1.18 1.24 0.10 0.15 96 h outside- outside static CoF > 1.26 1.38 0.15 0.25 96 h outside- outside

MDO Film Details:

[0217] During the MDO, the primary PE film from the blown-film line, the composition of which is shown in Table 7, is heated to an orientation temperature and the heating is preferably performed utilizing multiple heated rollers. The heated film is fed into a slow drawing roll with a nip roller, which has the same rolling speed as the heated rollers. The film then enters a fast drawing roll and uniaxially stretched for 5 to 7 times faster than the slow draw roll, which effectively orients the film on a continuous basis. The oriented film is annealed by holding the film at an elevated temperature for a period of time to allow for stress relaxation. Stretching was carried out using a monodirectional stretching machine manufactured by Hosokawa Alpine AG in Augsburg/Germany. The unit consists of preheating, drawing, annealing, and cooling sections, with each set at specific temperatures to optimize the performance of the unit and produce films with the desired properties. The heating was at 105 C., the stretching was done at 117 C., annealing and cooling was done at 110 C. down to 40 C. The primary film, made of LLDPE FX1002 and HDPEs MB5568 or FB5600 (all polymers can be purchased from Borealis and/or Borouge) obtained from blown film extrusion was pulled into the orientation machine, then stretched between two sets of nip rollers, where the second pair runs at higher speed than the first pair, resulting in the desired draw ration. Stretching is carried out with the respective draw ratios to reach the desired thickness of 21.5 microns.

TABLE-US-00007 TABLE 7 Composition of primary film (before stretching). Film Layer distribution (wt %) 15 10 50 10 15 FX1002 70 100 70 MB5568 or 100 30 30 100 FB5600

[0218] For all extruders, zone 1-5 were heated at 180 C., and the screen changer at 195 C.

Basic properties of the primary MDO-PE film:
Film thickness: 140 m
Draw ratio: 1:6.5
Final stretched film thickness: 21.5 m

[0219] Accordingly, the improved parameters of the films are reflected downstream to the respective inventive laminates produced with the films of the invention.