[China Packaging Network News] Soft plastic packaging stored in cold environments requires high cold resistance, that is, compared with the standard environmental conditions, the physical and mechanical strength of packaging materials such as impact resistance did not significantly deteriorate. If the soft plastic packaging has poor cold resistance, it will easily lead to the rupture of the finished product packaging in the low-temperature environment. Therefore, for the soft plastic packaging used in the low-temperature environment, the cold resistance is an extremely important physical and mechanical performance index. This article uses the FIT-01 film impact tester to test the anti-pendulum impact energy, and further describes how to verify the cold resistance of soft plastic packaging for users in related industries to ensure that soft plastic packaging is not easy to break in cold environments.
1, the meaning
Some items such as foods or medicines need to be stored in a low-temperature environment in order to ensure that they are not easily degraded or thawed. Sometimes the ambient temperature is required to reach minus 18 degrees Celsius, and this temperature threatens the quality of the contents, but endangers the external packaging materials. Performance may cause problems such as broken packaging and leakage. For example, when the frozen dumplings did not appear to burst at the production line, there was a rupture in the bags or seals after the frozen storage. The occurrence of the above quality problems is mostly related to the poor cold resistance of the packaging material, that is, the flexibility and impact resistance of the packaging material are deteriorated at a low temperature, resulting in an inability to withstand external impact.
Soft plastic packaging in the cold low temperature environment, physical and mechanical strength will be deteriorating, particularly vulnerable to brittle fracture, which is related to changes in the internal chemical structure of polymer materials at low temperatures. In order to improve the soft plastic packaging material is not easy to embrittlement at low temperature, you need to add additives such as toughening agents into its raw materials, but what is the cold resistance, whether it can withstand low temperature environment, should be verified by cold resistance test. Cold resistance is determined by comparing the impact resistance measured under standard ambient conditions with a temperature below minus 18°C. For example, the cold resistance is not less than a fixed percentage ratio (for example, the cold resistance of a BOPA/LDPE composite film needs to be not less than 60%) indicates that the physical and mechanical strength of the packaging material at a low temperature has not been significantly deteriorated. This article uses the FIT-01 film impact tester independently developed by Jinan Languang Electromechanical Technology Co., Ltd. to test the cold resistance of quick-freezing dumpling bags, providing technical references for related industries.
Figure 1 Frozen Food
2, the status quo
Most of the products that need to be stored under low temperature environment are made of soft plastic packaging, while the cold resistance of soft plastic packaging is mainly monitored by testing the anti-pendulum impact energy of packaging materials. At present, most of the soft plastic packaging materials used in low temperature environments in China are BOPA/LDPE, especially in the frozen food industry. The domestic cold resistance test methods for these materials refer to QB/T Bidirectionally Stretched Nylon (BOPA). / Low Density Polyethylene (LDPE) Composite Membrane, Bags, and the test method for anti-oscillating impact energy to be tested in cold resistance, please refer to GB 8809 "Plastic Film Anti-Pendulum Impact Test Method".
3, sample
A brand of dumplings packaging plastic bags.
4, testing equipment
In this paper, the Labthink blue light FIT-01 film impact tester was used to test the anti-pendulum impact energy under the standard environment and the sub-18°C environment. The cold resistance data of the sample was obtained through comparative calculation.
Figure 2 FIT-01 film impact tester
4.1 Test principle
The hemispherical punch of the thin film impact tester impacts at a certain speed and passes through the film sample to measure the energy consumed by the punch to evaluate the anti-pendulum impact ability of the film.
4.2 Application
(1) The equipment is professionally applied to the accurate determination of impact resistance of materials such as plastic films, sheets, composite films, and metal foils. It can also be used to test pendulum impact resistance of paper and paperboard, such as aluminum coated paper , Lele packaging aluminum plastic composite materials.
(2) The equipment meets a number of national and international standards: GB 8809-88, ASTM D3420, NF T54-116.
4.3 Equipment Parameters
l Impact energy is 1 J, 2 J, 3 J (expandable to 5 J) with a resolution of 0.001 J.
l The punch diameter is divided into two types: 25.4 mm, 19 mm and 12.7 mm. The rest of the non-standard sizes can be customized.
l The jaw diameter of the specimen on the device is 89 mm and 60 mm, respectively.
l The range is adjustable, and the electronic measurement can easily and accurately perform the test under various test conditions.
l The pneumatic clamping of the sample, the pneumatic release of the pendulum and the leveling assistance system effectively avoid systematic errors caused by human factors.
l The system automatically collects test data and visually displays the test results to the user.
l Support LystemTM laboratory data sharing system, unified management of test reports and test results.
5, the test process
(1) Take 10 pieces of 100 mm × 100 mm or 100 mm diameter specimens evenly in the width direction of the film, and place the specimens in a temperature of 23±2°C, 45% ~ 55%RH for at least 4 h, and Test in this environment.
(2) Test the center thickness of each sample, take the arithmetic average of the test results of the 10 samples, and record the sample thickness.
(3) Select the size of the punch according to the required impact resistance of the specimen, so that the reading is between 10% and 90% of the full scale of the instrument.
(4) Calibrate the instrument according to the rules of use of the instrument.
(5) Place the specimen flatly in the gripper to ensure that there is no wrinkling or excessive tension around the specimen. Ensure that the impact surface of the 10 specimens is consistent.
(6) Turn the pointer to the maximum scale, press the handle, quickly release the pendulum, make the pendulum impact the sample, record the reading displayed by the instrument.
(7) Cut 10 pieces of 100 mm × 100 mm or 100 mm diameter specimens evenly in the width direction of the film. Place the specimens in a temperature of -18°C for 2 h, and repeat steps (2) ~ (6). ) Continue to experiment.
(8) The anti-pendulum impact energy of the film measured after being placed in the -18°C environment is divided by the impact energy of the film against the pendulum measured under standard environmental conditions, ie, the cold resistance, in %.
Figure 3 sample test process
6, test results
The anti-pendulum impact energy of the film measured after being placed at -18°C was 1.400 J. The impact energy of the film against the pendulum measured under standard environmental conditions was 1.490 J, and the cold resistance was 94%.
7. Conclusion
Cold resistance is one of the important properties of soft plastic packaging used in low temperature environment. Soft plastic packaging with good cold resistance can effectively ensure that the finished product packaging is not easy to break under cold environment. In this paper, the cold resistance of quick-freezing dumplings was tested using the FIT-01 film impact tester. The test results are stable and the data is reliable, which can truly reflect the physical and mechanical strength of packaging materials at low temperatures. In addition to the testing equipment that can test the physical and mechanical strength of soft plastic packaging, Labthink also provides global customers with professional testing services and equipments such as barrier properties and hygienic chemical properties of soft plastic packaging. Learn more about Labthink's testing equipment With services, you can log in to view specific equipment information or to inquire. Jinan Languang Electromechanical Technology Co., Ltd. would like to take this opportunity to enhance the technical exchanges and cooperation with enterprises and institutions in the industry.