CPP film
CPP film is a non - tensile, non - directional polypropylene film, comparing with polyethylene, CPP film have below characteristics:
(1) CPP film, with good moisture resistance, its Water Vapor permeability is lower than PE film.
(2) CPP film is more transparent than PE film, with good gloss, high stiffness, less friction with the contents, and can maintain transparency, so the shelf display effect of packaged goods is good.
(3) CPP film can be cooked at more than 100℃, and there are varieties that can be cooked at 135℃. CPP film’s heat resistance is higher than that of PE film.
(4) CPP film, with good performance of oil resistance, is good for packing the oily food products.
(5) CPP film has good thickness uniformity, its thickness error is 4%, which cannot be achieved by blow-moulding.
However, homopolymerized CPP film, with narrow heat sealing temperature range and big brittleness, is suitable for single-layer packaging film, while copolymerized CPP film has a balanced performance, is suitable to be used as the inner layer material of the laminated film. At present, the CPP film used in the industry are generally Copolymerized CPP one. We can make full use of the characteristics of various polypropylene by combination, which will make the performance of CPP film more comprehensive.
The standard of CPP is QB/T 1125-2000, which is the same as that of CPE . The physical properties of CPP is shown as below table 2-5.
Table 2-5 CPP’s physical properties
Items | CPP | ||
thickness≤40（μm） | |||
Tensile strength（MPa） | vertical | ≥40 | ≥35 |
horizontal | ≥30 | ≥25 | |
Elongation at break（%） | vertical | ≥500 | ≥350 |
horizontal | ≥600 | ≥450 | |
haze（%） | ≤8 | ≤5 | |
Friction coefficient （non-treated surface） | Motion μd | ≤0.35 | |
Motionlessness μs | |||
Wetting tension（mN/m） | ≥38 | ||
