Cross laminating film for hollow board production line
DATE：2021/4/7 9:18:47 / READ： / SOURCE：This station
Cross laminating film for hollow board production line
Hollow board production line www.handern.comCross composite film is a new type of heavy packaging material. There are two ways to make cross composite films. One is to make single or coextrusion films, which are cut at 45 ° angle with the orientation direction after uniaxial stretching, and then cross composite films. Because the weak orientation part (or non orientation part) of each layer is covered with the strong orientation part of another layer, the composite film becomes firm in all directions, thus improving the strength characteristics of the composite film. The materials that can make the composite film are LDPE, HDPE, PP, PA and pet, while PE and PP are the main ones. The other direction is the composite film composed of inner, middle and outer layers, in which the inner layer is HDPE, oriented by transverse stretching after film forming, the outer layer is LDPE (or HDPE, or the mixture of HDPE and LDPE), oriented by longitudinal stretching after film forming, and the middle layer is eva, As an adhesive layer, the three layers become a cross composite film after lamination. This composite film has both the inner layer of transverse tension and the outer layer of longitudinal tension. As a result, the longitudinal and transverse tensile strength is greatly improved. The film of the middle adhesive layer and the oriented film enter into the compound roll vertically at 90 ° and the inner and outer layers enter into the compound roll at 180 ° respectively. It can be cross compounded with compound adhesive or hot melt compounding. EVA is hot melt adhesive, which is made by pressure melting and pressing. HDPE inner layer, mi0.04g/10min, density above 0.96g/cm3, melting point 131c, transverse tensile orientation at 120c, thickness 0.03 ~ 0.05 mm.EVA raw material MFR:0.5 ~0 g / 10 min, VA content 10% - 15%, density 0. 93 g / cm. The MFR of LDPE was 0.3 ~ 1.0g/10min. There are two main types of fresh-keeping, one is PVC, Because a lot of plasticizers are used in PVC fresh-keeping film, in Europe and the United States, even non-toxic plasticizers are required to transfer less than 10mng / DM to food. Moreover, PVC is difficult to process, and its moisture resistance is not as good as polyolefin. In addition to PVC, PVDC is also an excellent material for fresh-keeping film, but its price is relatively expensive. The other kind of plasticizer used in large quantity is polymer light film, which is used for the production of polyolefin fresh-keeping film According to hydrocarbon tree, it is less used. The resin is LDPE, EVA (MRF 0.3 ~ 0.6g/10min, VA content < 25%) and LLDPE. In order to make the policy shares have a certain degree of self-adhesive, we can add about 0.5% - 1% of vegetable oil: soybean oil, cotton oil, polypropylene and other materials in the polymer resin. In order to prevent water drops, we can add them from the source. Hollow board production line www.handern.com
The forming equipment requirements of cross composite film are as follows: first, the forming equipment of inner layer film: it is required to have efficient cooling effect and strict control of processing temperature, the transverse stretching temperature of film is 125 ~ 150C, and the blowing ratio is more than 5 times. Second, the molding equipment of outer and inner layer film: it is composed of two extruders for extruding EVA (middle layer) and LDPE (outer layer) respectively. After extrusion, the inner layer film is quenched, and then heated to 100 ~ 130c. After longitudinal stretching, it is thermally bonded with the inner and outer layers, and then heat-treated at 70c to eliminate internal stress. After cooling, it is rolled into cross composite film. Hollow board production line www.handern.com
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