Effect of Packaging Material Translucency on Product Shelf Life

First, the impact of light transmittance of packaging materials on the product

For the packaged products, the probability of direct exposure to sunlight is very small, but the items are exposed to sunlight and fluorescent light in the window display, on the counter, and on the shelves after the packaging. Because UVA has the ability to penetrate glass, fluorescent lamps can also emit ultraviolet light, so the impact of light on the shelf life of packaging products can not be ignored. It is understood that in the case of the same ambient temperature, humidity, and oxygen concentration in the packaging bag, the light transmittance of the packaging bag material has a great influence on the shelf life of the product.

Second, the light transmittance of packaging materials and precautions

Taking WGT-S transmittance/haze meter as an example, take AL/PE, PET/PE, PA/PE, OPP/PP/PE and other film samples, the size is 50mm×50mm.

1. Insert the power plug of the instrument into the socket, taking care to ensure that the grounding wire is valid. Then turn off the three protective covers of the instrument.

2. Turn on the power to warm up. Two windows display two decimal places. Ready indicates yellow light. Soon, the “ready” light indicates “P” on the left reading window of green light, “H” appears on the right, and a call sounds. . At this time, press the test switch in the case of blank sample, the instrument will display "P100.00", "H0.00", if "P100.0", "H0.00" is not displayed, ie P<100, H>0.00, Note that the light source is not warmed up sufficiently, and the power can be turned off and then on again. This is repeated 1-2 times. The instrument is warmed up for a few minutes under “P100” and “H0.00”. Press the “TEST” switch and the microcomputer collects the data of the instrument itself. , "P", "H" and call again, can be measured.

3, the film is clamped between the magnetic clamp slightly flat, and then can be installed on the sample stage test (the placement of the clamp should pay attention to the film side close to the integration ball), press the test button, the indicator light turns red, soon The numerical values ​​of the light transmittance and haze are displayed on the indicator screen. The former shows the unit of 0.1% and the latter is 0.01%. At this point, the indicator light turns to green light. When retesting is required, the sample may not be taken. Press the test button again to obtain multiple measurements, and then use the arithmetic mean value as the measurement result to improve the measurement accuracy. Replacing Samples Repeating TEST continuously measures the results of the same batch of samples.

The light transmittance of AL/PE composites is very small, and the average light transmittance is less than 0.9%. The light transmittances of PET/PE and PA/PE are very similar. The transmittance of PA/PE is in the wavelength range of 280 nm<λ<306 nm. Larger than PET/PE, the difference is smaller in other wavelength ranges. The transmittance of OPP/PP/PE materials in the wavelength range of 250nm<λ<290nm is much greater than that of PET/PE and PA/PE, and is much smaller than that of PET/PE and PA/PE in the wavelength range of 300nm<λ<900nm. .

4, through a large number of experiments can be drawn: different materials in the same wavelength range within the different light transmittance; different wavelength range within the same material light transmittance is also very different. According to relevant data, the deterioration of products is due to the fact that the product is sensitive to light waves within a certain range. For example, light waves in the wavelength range of 200-260 nm are the main factors for the deterioration of Tianjin Hemp Flower. Therefore, for twists, it is preferable to choose packaging materials that have a barrier effect to short wavelength light.

Third, the light transmittance of packaging materials to improve the methods and trends

Packaging materials can be controlled for light transmission by changing the amount of plastic nucleating agent (transparent agent). Dibenzylidene sorbitol (DBS) and di-(p-methyl)benzyl sorbitol (DTS) are different grades of plastic nucleating agents for the modification and processing of plastic products. They are extruded after adding plastics. , injection molding or blow molding, can get high transparency, high rigidity, high heat temperature of the sheet, film, plastic containers, beverage bottles, packaging materials.

For example, DBS is used in various grades of PP and PE products. When the amount is 0.2% to 0.5%, the haze of PP sheet decreases by 60%, and the LLDPE blown film and sheet haze decrease by 61% and 74%. Improve the transparency of plastic products. DTS is more effective than DBS in the transparency of plastic products.

According to relevant information, the new transparent agents developed in recent years, such as women's mouth EC-4, NE-4, NE-5, NE-6, and Millad 3988, provide comprehensive improvements in terms of transparency and food clarity. Performance. In the EU countries and the United States, the production of transparent agents grows at an annual rate of 8% to 10%, which is much higher than the 5% growth rate of general plastic additives. The Milad3988 product developed by Milliken Chemical Company in the United States in recent years has been said to represent a new level of development of the world's transparent agent, which can effectively improve the transparency of PP and will not impart odor to the product. It can be used in any processing technology.

In short, manufacturers need to fully understand the transparency of packaging materials to guide the choice of transparent agent types and dosage; the use of manufacturers need to master the transparency of packaging materials, according to different interior products, the length of sales, etc., select the packaging materials , to ensure the shelf life of the product.