Polyethylene based laminated film structure with barrier properties

Abstract

Laminated film structure including at least one first film having a thin ceramic or metal coating, being laminated to a second film and whereby the laminated film structure is based on polyethylene only, i.e. polymers other than polyethylene are substantially absent and whereby the laminated film structure has good barrier properties.

Claims

1. A laminated polyethylene based film structure having barrier properties, the laminated polyethylene based film structure comprising (1) one oriented first film comprising: a) at least one layer A based on a polyethylene polymer having a density of from 890 to 980 kg/m.sup.3, and b) at least one layer B, wherein layer B comprises: a high density polyethylene (HDPE) having a density of from 940 to 970 kg/m.sup.3, a medium density polyethylene (MDPE) having a density of from 925 to 940 kg/m.sup.3, or a linear low density polyethylene (LLDPE) having a density of 910 up to 950 kg/m.sup.3, wherein the oriented first film: is at least oriented in machine direction (MDO film) in a draw ratio of from 1:1.5 to 1:12 and has a film thickness after orientation of from 10 to 50 μm, and has one surface that is coated by a thin vapor deposited barrier ceramic or metal layer, such that the oriented first film has a coated surface having a thickness of from 5 nanometers (nm) to 200 nm; and (2) a second film laminated onto the coated surface of the oriented first film, wherein the second film comprises c) at least one sealant layer C based on a polyethylene polymer, and d) optionally a high density polyethylene (HDPE) barrier layer D, and wherein polymers other than ethylene based polymers are substantially absent from the laminated polyethylene based film structure.

2. The laminated polyethylene based film structure according to claim 1, wherein the polyethylene polymer of layer A is selected from the group consisting of a high density polyethylene (HDPE), a medium density polyethylene (MDPE), a linear low density polyethylene (LLDPE), a blend of a linear low density polyethylene (LLDPE) with a high pressure low density polyethylene (LDPE), and a blend of an ethylene based plastomer with a high pressure low density polyethylene (LDPE).

3. The laminated polyethylene based film structure according to claim 1, wherein the polyethylene polymer of layer A is a linear low density polyethylene (LLDPE) with an MFR.sub.2 (190° C., 2.16 kg, ISO 1133) in the range of from 0.01 to 20 g/10 min and a density in the range of from 910 to 950 kg/m.sup.3.

4. The laminated polyethylene based film structure according to claim 3, wherein the linear low density polyethylene (LLDPE) contains at least one or two C.sub.3-C.sub.10 alpha-olefin comonomer(s), wherein the LLDPE is produced using a Ziegler-Natta catalyst.

5. The laminated polyethylene based film structure according to claim 1, the at least one layer B comprises a layer of a high density polyethylene (HDPE) having a density of from 940 to 970 kg/m.sup.3.

6. The laminated polyethylene based film structure according to claim 1, wherein the oriented first film further comprises an additional layer E, wherein the layer E comprises a high density polyethylene (HDPE) having a density of from 940 to 970 kg/m.sup.3, a medium density polyethylene (MDPE) having a density of from 925 to 940 kg/m.sup.3, or a linear low density polyethylene (LLDPE) having a density of from 910 to 950 kg/m.sup.3.

7. The laminated polyethylene based film structure according to claim 6, wherein the oriented first film: is an unblocked film having the structure E/A/B, or is a blocked film having the structure E/A/BL/BL/A/B or E/A/A/A/BL/BL/A/A/A/B, wherein BL is a blocking layer comprising a blend of a LLDPE as used in layer A and an ethylene based plastomer with a density below 915 kg/m.sup.3.

8. The laminated polyethylene based film structure according to claim 6, wherein the layer E is the same as the layer B.

9. The laminated polyethylene based film structure according to claim 6, wherein the layer E is different than the layer B.

10. The laminated polyethylene based film structure according to claim 1, wherein the oriented first film is only oriented in machine direction.

11. The laminated polyethylene based film structure according to claim 10, wherein the machine direction oriented first film has i) a tensile modulus (according to ISO 527-3) in machine direction measured on a 25 μm MDO film at room temperature of at least 800 MPa, ii) a tensile modulus (according to ISO 527-1 and 527-3) in machine direction measured on a 25 μm MDO film at 70° C. of at least 100 MPa, iii) a ratio of i) to ii) of below 10, iv) a gloss(20°) according to ASTM D2457 for a film thickness of 25 μm of at least 30%, and v) a haze according to ASTM D1003 for a film thickness of 25 μm of below 30%.

12. The laminated polyethylene based film structure according to claim 1, wherein the coated surface of the oriented first film is coated with an aluminum coating, an AlOx coating, or a SiOx coating.

13. The laminated polyethylene based film structure according to claim 1, wherein the laminated polyethylene based film structure shows an oxygen transmission rate (OTR; ASTM F-1927; 23° C., 50% RH) of lower than 50 cm.sup.3/m.sup.2/1 day and a water vapor transmission rate (WVTR, ASTM F-1249; 37.8° C., 90% humidity) of below 5 g/m.sup.2/1 day.

14. A laminated article comprising the laminated polyethylene based film structure of claim 1.

15. A method of use of the laminated polyethylene based film structure of claim 1, the method comprising using the laminated polyethylene based film for producing vertical or horizontal form fill seal packaging, pouches, sacks, or bags.

Description

EXAMPLES

(1) The following film structures have been prepared:

Inventive Examples

(2) Coated first film:

(3) IE 1: PE-AlOx

(4) IE 2: PE-Al

(5) IE 3: PE-SiOx

(6) Laminated structure:

(7) IE 4: PE-SiOx/PE

Comparative Example

(8) CE 1: 12 μm PET/70 μm PE benchmark

(9) Commercially available standard 12 μm PET/70 μm PE laminate was used.

(10) Film Preparation

(11) First film of IE1, IE2, IE3 was coextruded on a 5-layer Alpine co-extrusion line with die diameter 400 mm, at a blow up ratio (BUR) of 1:2.7, frost line height 3D and Die gap 1.5 mm.

(12) The formed films had a thickness of 110 μm (blocked film).

(13) The composition of the 5 layers can be seen in Table 1:

(14) TABLE-US-00001 Layer A B C D E Borshape FX1001 wt % 98.5 98.5 98.5 80.0 Hostalen 7740 F2 wt % 96.5  — — — — Queo 8201 wt % — — — — 20   Polybatch ® AMF 705 HF wt % 0.5 — — — — POLYBATCH ® CE-505-E wt % 1.5  1.5  1.5  1.5 — Polybatch ® AB 35 VT wt % 1.5 — — — — Borshape FX1001: bimodal Ziegler Natta produced terpolymer (C2/C4/C6) Grade BorShape™ (provided by Borealis AG). FX1001 has MFR.sub.5 of 0.85 g/10 min, density of 931 kg/m.sup.3. Hostalen 7740 F2: high density polyethylene provided by LyondellBasell, MFR.sub.5 of 1.8 g/10 min, density of 948 kg/m.sup.3. Queo™ 8201: ethylene based octene plastomer, MFR (190/2.16) of 1.1 g/10 min, unimodal, density 882 kg/m′, produced in a solution polymerization process using a metallocene catalyst provided by Borealis AG). It contains processing stabilizers. Polybatch® AMF 705 HF: processing agent provided by A. Schulman. Polybatch® CE-505-E: is a 5% erucamide slip concentrate based in polyethylene provided by A. Schulman. Polybatch® AB 35 VT: anti-blocking and slip agent masterbatch provided by A. Schulman

(15) 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 115° C., annealing and cooling was done at 110° down to 40° C.

(16) The film 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 ratio. Stretching is carried out with the respective draw ratios to reach the desired thickness. (draw ratios and final thickness of MDO films are given in Table 2) After exiting the stretching machine the film is fed into a conventional film winder where the film is slit to its desired width and wound to form reels.

(17) The properties of the MDO film are also given in Table 2:

(18) TABLE-US-00002 TABLE 2 first film - oriented in machine direction First film Primary film thickness [μm] 110 Draw ratio 4.5 Final film thickness [μm] 25 Parameter Unit Tensile test MD/TD Tensile modulus MPa 860/1110 Tensile test 70° C. MD Tensile modulus MPa 232 ratio 3.7 Optics Gloss (20°) % 136 Haze % 4

(19) Coating with Barrier Layer

(20) The first film was coated with barrier layers (AlOx, Al, SiOx) at AMAT (Applied Materials, Inc.) to yield the films of IE1, IE2 and IE3

(21) The OTR and WVTR were measured on these coated first films using Mocon equipment. Te results are summarized in Table 3.

(22) TABLE-US-00003 TABLE 3 OTR and WVTR of coated first film IE1 IE2 IE3 PE-10 nmAlOx PE-40 nmAl PE-10 nmSiOx WVTR; 37.8° C., 5.6 1.7 3.1 90% RH (g/m2-day) O2; 23° C., 50% RH 966 395 543 (cc/m2-day)
Preparation of Laminate

(23) The lamination step was done on a commercially available Nordmeccanica lamination machine. As adhesive between the layers a commercially available two component solvent-based polyurethane adhesive from H.B. Fuller was used.

(24) As second film a commercially available standard 70 μm PE film was used (the same as is part of the laminate of CE1).

(25) IE 4: 25 μm PE-10 nmSiOx/70 μm PE

Comparative Example CE1

(26) 12 μm PET-layer/70 μm PE benchmark

(27) The OTR and WVTR were measured on these laminates using Mocon equipment. The results are summarized in Table 4.

(28) TABLE-US-00004 TABLE 4 OTR and WVTR of laminate CE1 IE4 PET/PE PE- benchmark SiOx/PE WVTR; 37.8° C., 90% RH 4.5 2.1 (g/m2-day) O2; 23° C., 50% RH 106 18.3 (cc/m2-day)