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Home > MacroLetter > 12.1 - Spring 2008 > Multilayer Milk & Beverage Films
Multilayer Milk & Beverage Films
Continued from MacroLetter 12.1 - Spring 2008
Specific Width Calculations for Milk Packaging Machines
Milk packaging machines typically require a film width of 900mm. With different die sizes and varying blow-up ratios (BUR), the optimal film width can be achieved.
With a 350mm (14”) blown film die and a BUR of 1.64:1, the layflat width of the film (flattened bubble) will be 900mm. The flattened film may then be slit at the edges to produce two 900 mm wide films, which can be wound into rolls on two separate winders.
If the die diameter is 550mm (22”), a BUR of 2.1:1 is required to produce a film width equaling 1800 mm, which means two rolls of 900 mm wide film can be produced per winder.
Typical Milk Film Structures
This section provides example structures for milk film produced on 5- or 7-layer blown film lines.
| Layer |
Composition |
Thickness
(microns) |
| 1 |
PE Blend |
36 |
| 2 |
Tie |
6 |
| 3 |
EVOH-38 |
7 |
| 4 |
Tie |
6 |
| 5 |
PE Blend |
36 |
The first example is for 5-layer film produced on a 350mm (14”) diameter die, with a total thickness of 90 microns, a BUR of 1.64:1, and film width of 900mm.
| Layer |
Composition |
Thickness
(microns) |
| 1 |
LLDPE |
25 |
| 2 |
PE + White MB |
11 |
| 3 |
Tie |
6 |
| 4 |
EVOH-38 |
7 |
| 5 |
Tie |
6 |
| 6 |
PE + White MB |
11 |
| 7 |
LLDPE |
25 |
The second example is for a 7-layer film structure, produced on a 350mm (14”) diameter die, with a total thickness of 90 microns, a BUR of 1.64:1, and a film width equaling 900mm.
Layer Configurations for 7-Layer Films
For the production of 7-layer milk packaging films on Macro's BXL 7-layer lines there are many layer combinations that can be used to make up the film, some of which are indicated in the table below.
| Layer |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
| Structure 1 |
PA 6 |
Tie |
PA 6 |
EVOH |
PA 6 |
Tie |
LLDPE |
| Structure 2 |
PA 6/66 |
Tie |
PA 6/66 |
EVOH |
PA 6/66 |
Tie |
LLDPE |
| Structure 3 |
LDPE |
Tie |
PA 6 |
EVOH |
PA 6 |
Tie |
LLDPE |
| Structure 4 |
LLDPE |
LLDPE |
Tie |
EVOH |
Tie |
LLDPE |
VLDPE |
| Structure 5 |
LLDPE |
LLDPE |
PP (random
copolymer) |
PP (random
copolymer) |
PP (random
copolymer) |
LLDPE |
mLLDPE |
| Structure 6 |
PP (random
copolymer) |
LDPE |
LDPE/HDPE |
LDPE/HDPE |
LDPE/HDPE |
LDPE |
LLDPE |
Looking for More?
Macro offers blown film technology (5 – 9 layers) to process resins such as LLDPE, mLLDPE, plastomers, LDPE, tie, cPP, EVOH and Nylon to make barrier films for milk and beverage packaging. For more information regarding the production of these and other types of barrier films, please contact us. Macro helps its customers achieve their processing goals with a complete technology transfer, such as technical know-how to process resins, film property testing and new formulation development.
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