Tea is one of the most distinctive and high-quality products in China, and its outer packaging is decorated with books and paintings, which enhances the added value of this special product. And the polyethylene film used for its inner packaging also requires special properties, mainly including no odor, opacity, and astringency.
The salivation film produced by ordinary film and LDPE has high transparency, no astringency on the surface of the film, and is not suitable for the requirements of tea inner packaging. Moreover, the film itself has a greasy odor, which is easily adsorbed by tea and can lead to tea flavor and spoilage. In response to the particularity of the film used for tea inner packaging, the 1C7A brand was ultimately selected through scientific screening of various spleen grade resins and appropriate adjustments to the salivation process
The salivation film produced by resin can meet the quality requirements of tea inner packaging.
- Selection of resin
In order to meet the requirements of product performance and processing technology, ordinary film grade resin adds some lubricants, smoothing agents, stabilizers and other additives to the synthetic resin. Most of these additives are lipid low molecular substances. After the resin is processed into a thin film, the additives will gradually migrate and precipitate towards the surface of the film, causing a greasy odor that is easily adsorbed by tea leaves on the surface of the film, resulting in tea flavor and deterioration. Similarly, due to the presence of additives in the resin, the film has good transparency and a smooth surface after film formation, which is not suitable for the special requirements of tea packaging films. However, 1C7A resin does not contain additives. After processing into a film, its surface has no oily odor, and the transparency of the film is poor. Its surface has a certain degree of astringency, making it suitable for the special requirements of tea inner packaging film. - Main equipment and technical parameters
(1) Extruder, screw diameter 90cm, L/D 30/1, maximum speed 120r/min.
(2) T-shaped machine head, with a width of 1200mm and a discharge gap of 0.04mm~1mm.
(3) Casting film cooling roller, with a diameter of 600mm and a length of 1400mm.
(4) The range of the B-ray thickness measuring device is 0-80um.
(5) Corona treatment device, with a power of 13kW.
(6) Dual station coiling device with a maximum coiling diameter of 500m - Process conditions and control parameters
(1) The screw speed is 50r/min
(2) The host current is 60A
(3) The extrusion back pressure is 0.12MPa
(4) The filter screen is 100 mesh with 3 layers
(5) The cooling roller temperature is 19 ℃
(6) The effect of corona treatment is that the surface wetting tension is ≥ 4 × 10-2N/m
(7) The opening scale of the mold lip is 0.05mm
(8) Film specifications: width 900mm, thickness (40×1) um
