Flexible packaging can play a good role in commodity display, small quantity distribution, easy to carry and other functions, the market is expanding rapidly. Packaging as an important means to ensure the long shelf life of products, its quality assurance can not be ignored. Choosing appropriate and effective test items is an important means to ensure product quality and reduce cost. No matter how good a product is, it is difficult to form a market if it is not recognized by consumers. In addition to product quality requirements, consumers also have requirements on packaging materials, packaging design, ease of use, portability, shelf life and product price. The demand of consumers directly affects the seller's requirements for the goods in the market, and the seller will use these requirements to restrict his suppliers. These requirements are conveyed layer by layer, involving all aspects of packaging materials from production to final consumption. Comprehensive analysis, in order to make the packaging meet the requirements of various aspects, the inspection to be carried out can be summarized into the following categories: preservation (protection), safety, processing adaptability, convenience, commodity and other detection of content quality.
This paper mainly introduces the testing requirements for the physical properties of packaging materials, including the inspection of the quality preservation (protection), processing adaptability and convenience.
Preservation of content quality
1. Barrier properties of materials
The barrier performance of materials directly affects the quality of commodities. Poor barrier properties of materials can lead to deterioration, invalidation and loss of use value. This kind of barrier includes water, steam, gas, light, fragrance, smell and so on, and whether the insulation performance is good.
Generally, transparent materials are the most commonly used materials for flexible packaging. If the contents are required to be protected from light, the light transmittance of the materials can be effectively reduced by vacuum aluminizing the materials, compounding the materials with metals, or adding specific light absorbents to the materials. The thermal insulation performance of flexible packaging materials is often not very concerned, because the volume of goods packaged with flexible packaging materials is generally small. If the storage temperature is required, the insulation box can be used to control the environmental temperature.
Generally speaking, the barrier performance of materials mainly refers to the testing of water vapor, gas (such as oxygen, nitrogen, carbon dioxide and other inorganic gases) and organic gases such as fragrance. Generally speaking, the barrier of materials to water vapor and conventional gases (especially oxygen) can directly affect the storage, sale and storage quality of the contents in a certain environment for a certain period of time. For example: in the specified storage environment, whether the product quality can be maintained within the specified shelf life. This is particularly important for food packaging and drug packaging, and because of the particularity of drug use, the barrier performance of drug packaging materials is often higher. Labthink began to develop barrier testing equipment in 2001. After 8 years of continuous exploration, Labthink series of air permeability and moisture permeability testing equipment has been formed. The test methods basically include various methods commonly used in the world. The developed series of air permeability test equipment include: VAC series gas permeameter using vacuum differential pressure method, perme series and toy series container membrane oxygen permeability tester using the principle of equal pressure method of oxygen sensor; tsy-t series of moisture permeability test equipment include: tsy-t1 and tsy-t3 (12 chamber test) moisture permeability tester using weight reduction method, perme series and tsy-w series using electrolytic analysis method Water vapor transmission tester for container film. At the same time, it also has the detection equipment of dynamic relative humidity measurement method, infrared verification method and electrolytic analysis method.

The organic gas barrier test is a higher level test in the barrier test. The aroma retention performance of packaging materials belongs to the category of organic gas barrier test. Generally, not all packaging materials need to be tested for organic gas barrier. Some experimental results show that the higher the barrier of the material to oxygen and water vapor, the better the barrier property to organic gas. In order to meet customers' requirements for organic matter penetration, Labthink blue light has launched the world's first perme or2 / 410 organic gas permeability test system, which well meets the material's testing requirements for organic barrier properties.

2. Mechanical protection
Mechanical protection is one of the basic testing items of packaging materials. The test data directly affect the packaging damage caused by external natural factors or human factors in the process of transportation and sales. Including impact, shaking, stacking strength detection.
The test of transport package is to test the protection performance of the package to the contents by analyzing different circulation environment, simulating each link, and finding out the main causes of package damage, so as to achieve the purpose of protecting products. This kind of testing needs to simulate the circulation environment, so as to detect the impact of environmental factors. For example, when the package is stored in the open air, it will be affected by rain, sunlight, insect damage and microorganism. However, these simulation tests need to be carried out in one or more simulated laboratory environments, and only one equipment can not meet the test requirements.
For the inner package or small package, the sealing performance of the package can be tested after a series of simulation tests (such as shaking test, drop test, pressure test, etc.).
3. Stability
The detection of material stability is also one of the basic testing items of packaging materials, and the purpose of testing is to ensure that the package is not damaged during transportation and storage. As we all know, commodities have to go through production, transportation, sales and other links, and the environment changes greatly. For example, products made in the tropics are sold to the temperate zone. The production is carried out in a high temperature and high humidity environment, but the ambient temperature and humidity are low and relatively dry when they are sold. Therefore, the stability of materials for environmental changes is very important. The common test item is the thermal dimensional stability of thin films. Generally, there are two heating methods for thin film samples: liquid bath and air bath. The liquid bath is divided into water bath and oil bath. The selection of heating mode should be considered according to the requirements of materials and the characteristics of materials.
Processing adaptability
1. Machinability
Tensile property is one of the most important and basic mechanical properties of materials. Almost all packaging materials should be tested for tensile properties. The tensile properties can be tested by tensile test. The tensile strength, elongation and other indicators of materials are very important for film suppliers and users. These indicators determine the specific parameters of the processing production line during the secondary processing of the film, have an impact on the processing speed of the processing line and the traction force of the equipment, and are also the basis for the material processor to judge the performance indicators of the processed products.
In fact, the test for measuring tear strength mainly measures the energy required for tear growth. The main measurement methods are trouser method and elemendorf tearing method, and the elemendorf tearing method for constant radius specimens is preferred. For film processors, too high or too small tear strength may be detrimental to the processing process. For consumers, the tear resistance of materials is a main index related to whether the package is easy to open.
In the actual packaging process, the friction force is often both drag force and resistance, so the friction coefficient must be effectively controlled to make it in an appropriate range. In general, the inner layer friction coefficient is small, while the outer layer friction coefficient is moderate. However, the friction coefficient of the inner layer should not be too small, otherwise it may lead to the instability of the stacking material during the bag making process, and the outer layer friction coefficient will cause too much resistance in the packaging process, which will lead to the tensile deformation of the material. If the friction coefficient of the outer layer is too small, it may cause the sliding of the driving mechanism, resulting in inaccurate tracking and cutting positioning of the electric eye. In the study of friction coefficient of materials, special attention should be paid to the influence of temperature on friction coefficient. The friction coefficient of the material may increase or decrease with the change of temperature, and it may also maintain certain data stability. Considering that the actual operating temperature of the production line is often not well controlled in the room temperature range, it is necessary not only to measure the friction coefficient of packaging materials at room temperature, but also to investigate the friction coefficient under the actual use environment temperature. In order to complete the variable temperature test, the ambient temperature of the laboratory can be changed (it is preferable when the required temperature is not different from the room temperature), or the automatic temperature function of the testing equipment can also be used.

Whether the thickness of the material is uniform or not also has an important influence on the performance of the material. If the thickness of a batch of films is not uniform, the tensile strength and barrier properties will be greatly affected. Material thickness uniformity has become one of the basic indicators of flexible packaging material manufacturing. Because of the compressibility of flexible packaging materials, mechanical thickness gauge has been widely used in the field of flexible packaging. Mechanical thickness gauge can be divided into point contact type and surface contact type. It is a kind of contact thickness measurement method. It is essentially different from non-contact thickness measurement method. It can apply certain pressure (point contact force or surface contact force) on the surface of the sample before thickness measurement, so as to avoid measuring those with certain compressibility, uneven surface, everywhere The phenomenon of inaccurate measurement may occur when the non-contact thickness gauge is used for materials with uneven thickness. The mechanical thickness gauge adopts the most traditional thickness measurement method, the measured data is stable and reliable, and has no selectivity to the test object.
2. Printing adaptability
Adhesion, wear resistance, printing accuracy and other indicators are mainly proposed for the characteristics of the printing industry. A product with good packaging quality should not only have good protection, but also have excellent printing quality. Packaging is the coat of a commodity, but also represents the image of a brand. If only good protection, but no high-quality printing, it is not a high-quality packaging. Promoting sales is one of the main functions of modern packaging, packaging has become an important means to improve the competitiveness of goods and promote sales. Excellent printing is the Stormtrooper to realize the marketing strategy of an enterprise. Without excellent printing, it is bound to achieve half the result with half the effort if you want to create a good brand and enterprise image.
3. Sealing and adhesion
Heat sealing bag making is the last procedure of the whole flexible packaging process. The heat sealing bag requires good heat sealing fastness and can withstand the post-processing of the bag without leakage. The sealing tightness is closely related to the correct selection of heat sealing material, heat sealing pressure, heat sealing temperature and time, and heat sealing method. The quality of heat sealing has a direct impact on the overall barrier of the package, because the seal is the most prone to leakage. As long as a package has leakage, no matter how good the barrier material is used. Similarly, in the actual use process, most of the packaging damage occurs in the heat sealing part, which is mainly due to insufficient heat sealing strength, improper heat sealing performance, improper heat sealing device and heat sealing conditions.
For composite materials and adhesives, the peeling and bonding properties of materials are very important, which should be paid attention to by the packers. By testing the peel strength of the material, the stability of its own characteristics of common packaging materials such as composite film can be ensured, so that it will not lead to the separation between layers and destroy the barrier performance when the strength is low.
Convenience
Generally speaking, flexible packaging parts are not directly used for logistics transportation, because flexible packaging materials are very soft materials. Although they can protect products from the impact of environmental changes, their mechanical properties and mechanical protection properties often fail to meet the requirements of logistics transportation. The common outer packing mainly has the carton, also has uses the metal box or the hard plastic box.
For the preservation of products after opening the packaging, there are more research and development in this area in recent years, but the popularity is low. Now it seems that plastic bottle is a popular packaging form which is easy to open and re seal. From the initial packaging of milk and mineral water, it has been widely used in fruit juice, beverage, beer, and some seasonings. The development prospect is very broad. The gradual withdrawal of pop-up cans from the beverage packaging market is related to its characteristics that it is not easy to keep after one-time opening. Plastic bottle packaging is popular because it is easy to carry and store after opening.
In the face of fierce market competition, product packaging can meet the protection, safety and machinability of content quality, and then pursue the cost minimization, which is as important as improving the production efficiency of enterprises, opening up the market and maintaining the brand image. Comprehensive quality inspection and selection of appropriate quality inspection equipment are the basis for reducing packaging cost and ensuring packaging quality.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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