Polyethylene based laminated film structure with barrier properties
Laminated film structure comprising 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.
1. A laminated polyethylene based film structure having barrier properties, the laminated polyethylene based film structure comprising
(1) one oriented first film only oriented in the machine direction and comprising:
a) at least one layer A based on polyethylene polymer having a density of 890 to 980 kg/m 3 and
b) optionally at least one layer B, wherein layer B comprises: a high density polyethylene (HDPE) having a density of from 940 to 970 kg/m 3 , a medium density polyethylene (MDPE) having a density of from 925 to 940 kg/m 3 , or a linear low density polyethylene (LLDPE) having a density of from 910 to 950 kg/m 3 ,
wherein the oriented first film:
is only oriented in machine direction (MDO film) in a draw ratio of from 1:1.5 to 1:12,
has a film thickness after orientation of from 10 to 50 μm,
has one surface that is coated by a thin vapour deposited barrier ceramic or metal layer, such that the oriented first film has a coated surface, wherein the thin vapour deposited barrier ceramic or metal layer has a thickness of from 5 to 200 nm;
and
(2) a second film, wherein the second film comprises
c) a sealant layer C based on a polyethylene polymer, and
d) a high density polyethylene (HDPE) barrier layer D,
wherein the sealant layer C or barrier layer D is directly laminated onto the coated surface of the oriented first film; 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 of 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 of claim 1 , wherein the polyethylene polymer of layer A is a linear low density polyethylene (LLDPE) with an MFR 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 3 .
4. The laminated polyethylene based film structure of claim 3 , wherein the linear low density polyethylene (LLDPE) contains at least one or two C 3 -C 10 alpha-olefin comonomer(s), wherein the LLDPE is produced using a Ziegler-Natta catalyst.
5. The laminated polyethylene based film structure of claim 1 , wherein the oriented first film includes at least one layer B, and wherein the at least one layer B comprises a layer of a high density polyethylene (HDPE) having a density of from 940 up to 970 kg/m 3 .
6. The laminated polyethylene based film structure of 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 3 , a medium density polyethylene (MDPE) having a density of from 925 up to 940 kg/m 3 , or a linear low density polyethylene (LLDPE) having a density of from 910 up to 950 kg/m 3 .
7. The laminated polyethylene based film structure according to claim 6 , wherein the layer E is the same as the layer B.
8. The laminated polyethylene based film structure according to claim 6 , wherein the layer E is different than the layer B.
9. The laminated polyethylene based film structure of claim 1 , wherein the machine direction oriented first film has:
i) 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,
ii) a gloss (20°) according to ASTM D2457 for a film thickness of 25 μm of at least 30%, and
iii) a haze according to ASTM D1003 for a film thickness of 25 μm of below 30%.
10. The laminated polyethylene based film structure of claim 1 , wherein the coated surface of the oriented first film is coated with an aluminium, an AlOx coating, or a SiOx coating.
11. The laminated polyethylene based film structure of 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 3 /m 2 /1 day and a water vapour transmission rate (WVTR, ASTM F-1249; 37.8° C., 90% humidity) of below 5 g/m 2 /1 day.
12. A laminated article comprising the laminated polyethylene based film structure of claim 1 .
13. 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.