The hottest metal OPP film will replace the metal

Metal plated OPP film will replace metal sheet

for a long time, people have believed that aluminum foil is an ideal barrier layer for laminated packaging film structure requiring low moisture vapor and oxygen transmission. In fact, the wet vapor transmission rate (MVTR) and oxygen transmission rate (OTR) of flat aluminum foil are close to zero. Because of these properties, it has traditionally been used in paper/polyethylene/sheet metal/polyethylene (PPFP) structures. At the same time, the outer paper can be printed and coated to improve its appearance

commonly packaged in PPFP structure in food include ingredient powder, seasoning, soup, rice, toast, stuffing, dry cheese, nutrition/energy drinks and candy. These foods require that the packaging not only ensure that they are not degraded, but also have good puncture resistance, because many foods have sharp edges and corners. In the highly competitive market, cost saving is also an important aspect to be considered

options other than aluminum foil

however, today's development of metal plating technology provides processors and end users with another option other than sheet metal. Metallized polypropylene (MOPP) film now allows processors and end users to develop "sheet free" packaging, which has the advantages of stronger barrier, beauty, puncture resistance and economy compared with aluminum foil structure. The new metal plated OPP product of Toray plastics USA is an ultra-thin 45 gauge film called pcf-2. This film is made with proprietary technology and requires government policy support. It may be the thinnest MOPP available in the packaging industry at present

thin films is that they can be made in a larger area per pound of film. When the thickness is 45 gauge, the ultra-thin MOPP film can produce 68200 square inches/pound per pound compared with 36000 square inches/pound for the ordinary 0.000285 inch metal sheet and 41100 square inches/pound for the popular 0.00025 inch metal sheet. Although the output of thin films per pound is higher - more than 65% of the thinnest aluminum sheet, their wet vapor transmittance (MVTR) and oxygen permeability (OTR) are still very low. The typical MVTR at 100 ° F and 90% relative humidity (RH) is only 0.01 g/100 in2/day, and the OTR at 73 ° F and 0% RH is 1.5 ml/100 in2/day

bonding

a common problem faced by processors is the delamination of the traditional PPFP structure after repeated treatment, which often occurs in food packaging in the retail environment. However, the new MOPP film that can be used now can help overcome this problem. Compared with PP treated by conventional corona, it can provide better metal adhesion and stronger bonding strength between non-metallic lamination and extrusion lamination or coating. The metal adhesion strength of the new MOPP film exceeds 400g/in, and delamination is generally impossible. Figure 3 shows the comparison between the metal adhesion strength of this film and that of general laminated MOPP

the new metallized film not only provides better metal adhesion than the traditional PPFP structure, but also has better adhesion than the non-metallic surface of extruded lamination and coated film. For example, the adhesion strength of the non-metallic surface of the new MOPP film is tested by using a layer of extruded coated low-density polyethylene (LDPE) with continuous price increase of copper foil. The measured adhesive strength is 477g/in, which is almost 30% higher than 369g/in of traditional MOPP structure. Compared with PPFP structure, the new MOPP films can also provide better puncture resistance, although they are very thin

flexibility

the initial properties of the new MOPP film have advantages over the traditional PPFP structure. After repeated operation and treatment, its advantages will even become more obvious. Unlike the pinholes formed only a few minutes after the metal sheet is bent, the MOPP film can maintain its barrier property after repeated bending. In order to simulate the real environment that this type of repetitive deflection may encounter, Toray plastics USA tested new ultra-thin MOPP films and samples of traditional PPFP structures sampled with gelbo tester

gelbo tester is composed of two mandrels with a diameter of 90 mm that can fix the sample. One is movable and the other is fixed. The relative distance at the beginning of each cycle is 180 mm. Bend the tested sample by repeatedly twisting and rolling the film, usually 45 cycles per minute. According to the samples tested, the severe intensity and number of test strokes will vary. Determine whether there are pinholes by coloring the entire twisted film with white as the background color with colored rosin

by performing this test, Toray's new MOPP film can withstand repeated "twisting" and "rolling" cycles without pinholes and loss of barrier in recent years for at least 16 cycles. The traditional PPFP structure can't bear it after 7 cycles, and repeated distortion will make the situation deteriorate rapidly

another important advantage of the new MOPP film is that it can maintain its beautiful appearance for a long time even under the condition of exceeding the normal processing intensity. Aluminum foil can't recover creases and wrinkles, and it can't recover after any deformation, which makes the food packaging look very old. On the other hand, the new MOPP film packaging has flexibility and can recover any deformation caused by processing and operation, so it can maintain its original shape and charm no matter how many times it has been processed by customers or store employees

the limitation of aluminum cost

in terms of economy, the new MOPP film has more advantages than the traditional PPFP structure, because food manufacturers can produce more packaging with the same weight of film, Another reason is the consideration of aluminum price. The growth rate of aluminum and aluminum alloy costs is higher than that of polypropylene. In addition, the high demand for aluminum materials in the U.S. market to continue to further improve the production process of waterborne and solvent-free synthetic leather will make its price higher. As a result, the price gap between aluminum and polypropylene will widen

in order to reduce the cost of traditional PPFP structure, processors resort to finer specification sheet metal. However, this is not very helpful for the initial barrier property of the substrate, and even makes pinholes easier to appear in the normal processing process. On the other hand, the short-term and long-term barrier properties of the new MOPP film will not increase with the increase of thickness. In fact, the new 45 gauge film has the same barrier property as the 80 gauge MOPP film

compared with the traditional PPFP structure, the emerging MOPP film in this industry represents an important technological progress, which can provide all the above advantages

source: packaging Digest China