Abstract: This article describes in detail the characteristics of the use of flexible packaging materials and packaging functions, and describes the requirements for the detection of conventional physical properties, the necessity of detection, and the precautions for detection. At the same time, Labthink's services and functions are also introduced.
Key words: polymer, flexible packaging, physical properties, chemical properties, packaging functions
The application of high-polymer materials has changed the shortcomings of bulky, complicated and single-function packaging in the past. Therefore, it has been widely used in the food, pharmaceutical and other industries. At the same time, due to the customizable polymer properties, the characteristics and design of the contents The intention of the person to design the structure of the packaging material becomes possible. According to statistics, at present, the domestic plastic packaging (including containers and tools) accounts for about 30% of food packaging, and it is gradually increasing, and its growth rate exceeds that of paper food packaging. In recent years, China has stepped up supervision of quality control of packaging materials. However, there are still some hidden dangers in the safety performance of food packaging. There are still many problems in the quality of food packaging. To this end, starting this year, China has begun mandatory product certification for food packaging/container products to enhance the quality assurance of plastic packaging.
1. Packaging function and testing requirements
The basic functions of modern packaging include three aspects: protection function, convenience function and promotion function. A product arrives at the hands of consumers from the completion of the packaging, and it has to go through handling, transportation, storage, display, etc. There are many factors that can damage the contents in each link. The protection function of the packaging is to prevent these Destructive factors Loss of product quality and quantity during the logistics process. The convenient functions of packaging include convenient loading, convenient transportation, convenient loading and unloading, convenient stacking, convenient opening, etc., and have certain requirements on the performance of the selected packaging materials. For example, in order to facilitate opening and use, materials are required to have suitable mechanical properties. The packaging promotion function is mainly achieved through packaging and decorating design and styling design, with reasonable and pleasant colors, patterns and styling, which depends to a large extent on the shape, color, texture, transparency, gloss and printing of the material. Adaptability and so on.
For food packaging, especially for flexible packaging, plastic films need certain physical and chemical properties under the premise that they can complete the above packaging functions. Physical properties generally include mechanical properties, thermal properties, optical properties, barrier properties, etc. Except for the barrier properties, they can be collectively referred to as conventional physical properties and can be detected using conventional testing equipment. The chemical performance indicators include evaporation residue, potassium permanganate consumption, heavy metal content, and residual organic solvent, which need to be detected by chemical reagents or meteorological chromatographs. This article focuses on the detection of conventional physical properties of materials.
2. Routine physical properties testing of packaging materials
The detection of conventional physical properties is the basis of quality assurance. The purpose of the test is to avoid the package from being damaged before the intended packaging effect is achieved. If the general physical properties of the packaging material are not tested properly, possible damage to the packaging will render the entire protective function of the packaging material ineffective. The use of any functional materials and materials with the best chemical properties is futile. Conventional physical property tests include the detection of mechanical properties, thermal properties, and optical properties of materials. In addition, according to the different applications of materials, there are also different requirements for the combustion properties, electrical properties, and media resistance of materials. Therefore, the testing items for materials It should be determined according to the specific packaging application.
For the majority of flexible packaging manufacturers, the testing requirements for the mechanical properties of materials are the strongest. Mechanical properties include tensile properties, bending properties, impact properties, shear properties, friction properties, heat sealing properties, etc. Any failure to meet the standards may lead to the breakdown of the package or the failure of the production line. For example, the heat seal performance of a material includes detecting the heat seal strength (Hot Tack) when the heat seal portion is still relatively hot (not yet cooled to ambient temperature) and the heat seal strength after the heat seal portion is cooled down (Ultimate). Strength). The heat-sealed bag is commonly used in daily chemical product packaging, food and drug packaging, etc. Most of the filling methods on the flexible packaging production line are to allow the product to fall from a certain height into the packaging bag, which will impact the bottom of the packaging bag if it is in the filling process. The bottom of the package cannot withstand the breaking force caused by the filling of the contents, and cracking of the bottom occurs, resulting in broken bags. In order to effectively control the breakage rate of the production line, we pay more attention to the heat seal strength of the material after the heat seal has not been completely cooled after heat sealing. This is the so-called Hot Tack of the material. However, due to the stacking of packaging materials in the storage and transportation process, if the contents are liquid or use modified atmosphere packaging, the heat seal strength of the packaging cannot withstand the external pressure during the storage and transportation process, and it will appear broken. Bag phenomenon, so there is a certain requirement for the heat seal strength of the material after the heat sealing part is cooled.
Thermal properties include thermal stability, linear expansion coefficient, thermal conductivity, low temperature test, etc. Among them, the flexible package related industries are most concerned about the thermal stability and low temperature test of materials. The heat shrinkability of the material is one of the thermal stability of the material, and this index later became an important detection index of the shrink film. Optical performance is also a very important indicator. When packaging light-sensitive foods, special attention must be paid to the detection of the optical properties of the material. The main test items are the light transmittance and haze of the material.
3. Test the influencing factors
Conventional physical testing projects can basically use the corresponding testing equipment to detect, but for the same indicator, there may be more than one detection method, and the test environment and the size of the sample and pretreatment will affect the test results. Taken together, the main factors affecting the test are: test environment, pretreatment, and test methods used.
The test environment will influence the test results. For example, different temperatures will cause significant changes in the coefficient of friction. Humidity will also affect the test results of some of the polymers, especially for polar polymers.
The pretreatment environment and the length of pretreatment will affect the test results. This is mainly due to the inconsistent manufacturing environment of the sample and the incomplete elimination of internal stress. The comparison test needs to be performed under the same pretreatment environment and pretreatment time. .
Different test methods, the test results are not comparable, so in the comparison of material properties must be carried out under the premise of the test method and a variety of test conditions (ambient temperature and humidity, test speed, etc.) are the same. For China's flexible packaging industry, the purchase of testing equipment that fully implements China's national standards is an effective way to improve the comparability of material data.
4. Labthink Blue Light Laboratory
Labthink Bluelight Labs provides routine physical testing of customer samples and displays Labthink Bluelight's conventional testing equipment. The laboratory is equipped with a series of routine performance testing equipment developed by Labthink and developed by Labthink, including mechanical performance testing equipment, thermal performance testing equipment, optical performance testing equipment, and a series of ink printing quality testing equipment, using these routines. The testing equipment can perform analysis and analysis of mechanical properties, thermal properties, optical properties and printing quality of inks, and give a comprehensive evaluation of material properties to help flexible packaging manufacturers to judge whether the material properties meet the requirements for use. With the help of the testing equipment in Languang's conventional laboratories, it is fully possible to meet the needs of the national standard for testing the physical properties of materials (except for the barrier index, the barrier index can be measured by the blue light barrier laboratory). Food packaging manufacturers and related suppliers provide comprehensive testing services through 3C certification.