The hottest new trend of convenience food packagin

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New trend of "convenience food" packaging (1)

barrier packaging materials barrier packaging materials refer to packaging materials with good barrier properties. Check whether the friction moving parts should be filled with lubricating oil. Usually, barrier refers to the barrier ability of packaging materials to non-polar gases such as oxygen and water vapor

the oxygen barrier performance of packaging materials has a great impact on the storage period of processed food. When choosing packaging materials, they are often expected to have high oxygen resistance, that is, the so-called high barrier packaging materials are used. The gas barrier of packaging materials is usually characterized by the air permeability of packaging materials, that is, under the condition of 0.1 MPa (1 atmospheric pressure) gas pressure difference on both sides of the packaging materials, the milliliters of gas passing through in 24 hours per square meter. The greater the air permeability, the worse the barrier; On the contrary, the smaller the air permeability, the better the barrier. As for the distinction between high barrier, medium barrier and low barrier, there is no strict definition so far. From a practical point of view, some people call a film with a thickness of 2.5 wires (0.025 mm) whose air permeability is less than 5 cubic centimeters (square meters.24h..0.1mpa) as a high barrier packaging material; The air permeability between cubic centimeter (square meter.24h..0.1mpa) is called barrier packaging material; Those with air permeability greater than 200 cubic centimeters (square meters.24h..0.1mpa) are called low barrier packaging materials. The moisture permeability of packaging materials also has a significant impact on the quality of packaged food. Controlling the moisture in food within a certain range is often not only the need to maintain the flavor of food, but also the existence of moisture, which often contributes to the reproduction of bacteria and accelerates the deterioration of food. Many foods need to be stored in a dry state. Packaging materials are required to have good performance of blocking water vapor, which can effectively prevent the water vapor in the air from entering the food. The barrier of packaging materials to water vapor is usually described by the moisture permeability of packaging materials, that is, the grams of water vapor per square meter and 24 hours are characterized. A film with a thickness of 2.5 wires (0.025 mm) and a penetrant of less than 5g/(square meter.24 hours) is called a high barrier (high moisture resistance) packaging material, and a packaging material with a moisture permeability of between g/(square meter.24 hours) is called a barrier (moisture resistance) packaging material; Those with moisture permeability greater than 20g/(M2.24h) are called low barrier (low moisture resistance) packaging materials

there are two kinds of barrier packaging materials commonly used for convenience food, one is the composite packaging material containing aluminum foil and inorganic coating, and the other is the full plastic barrier composite packaging material. Traditional aluminum-plastic composite packaging materials contain aluminum foil, which is the most barrier packaging materials in common use. Its oxygen and moisture permeability are close to zero, and it can prevent the transmission of visible light and ultraviolet light. In addition to preventing the entry of oxygen and water vapor outside the food packaging container and the harm of oxygen and water vapor to food, it can also prevent the deterioration of photosensitive components of food caused by the action of visible light and ultraviolet light, which has extremely excellent protection for the packaged food. Moreover, when the heat sealing layer adopts high-temperature resin, such as polypropylene, the composite material based on aluminum foil has digestibility, Therefore, it has a wide market in the packaging of convenience food. So far, it is widely used in cooking packaging, vacuum packaging, gas replacement packaging and other fields

in order to solve the problem that the barrier performance is greatly reduced due to the fracture of aluminum foil, people have successfully studied vacuum aluminum plating (also known as vacuum aluminum spraying) on the surface of plastic film, mainly on the surface of PET film and BOPP film, to manufacture composite soft packaging materials with aluminum coating. This material has the performance of blocking oxygen, water vapor and light transmission close to that of composite materials containing aluminum foil, Moreover, when it is folded, it is not easy to produce cracks, and its inherent high barrier property can still be maintained. The composite material with vacuum aluminized coating also has better gloss than the composite material with aluminum foil, and through the coloring of the aluminized base film, it can obtain a variety of colors such as golden yellow, silver white, bright red, etc., to meet the needs of decoration. In addition, because the thickness of the aluminum coating is significantly lower than that of the aluminum foil, the use of aluminum base film instead of aluminum foil to produce high barrier composite packaging materials also has the characteristics of saving materials

in order to manufacture highly transparent composite packaging materials with the same barrier property as composite packaging materials containing aluminum foil, people have developed a base film containing evaporated aluminum oxide or silicon oxide layer (using physical or chemical methods, plating a layer of dense silicon oxide or aluminum oxide on the surface of PET film). The composite film made of this base film has extremely high oxygen resistance, moisture resistance, oxygen permeability The moisture permeability is equivalent to that of the aluminum-plastic composite film containing aluminum foil. At the same time, it also has a high degree of transparency. The packaged goods can be clearly seen through the packaging, which has a good display effect on the goods. In addition, because the composite material does not contain aluminum layer and has excellent microwave permeability, it can be well used in microwave food popularity that aluminum composite packaging materials cannot be used, and it will be further expanded in packaging

all plastic barrier composite packaging materials include high barrier all plastic composite packaging materials and barrier all plastic composite packaging materials. Industrialized high barrier all plastic barrier composite packaging materials. The commonly used barrier resins include polyvinylidene chloride (PVDC), ethylene vinyl acid copolymer (EVOH), aromatic nylon MXD6, etc. they can not only produce transparent high barrier packaging materials, but also are thermoplastics. The required composite packaging materials can be directly produced from plastic pellets by coextrusion. 3. When there is no experiment for a long time, Implement cleaner production. Because of their thermoformability, they can be deep drawn and processed into containers of the desired shape

polyvinylidene chloride is a variety with outstanding advantages and disadvantages. It is the only polymer commonly used in the packaging field that has a high barrier to oxygen and water vapor at the same time. Although its molding performance is worse than that of common thermoplastic, under specific molding conditions, it can not only produce single-layer flat film and tube film, but also produce multi-layer coextrusion composite film by coextrusion, High barrier packaging materials containing PVDC coating with relatively low cost can also be prepared by lotion (or solution) coating. Therefore, PVDC was once regarded as the most promising barrier material. However, the environmental adaptability of PVDC is extremely poor. Waste packaging can not be recycled through melting granulation, and it is not easy to decompose. When burned, toxic and harmful substances such as hydrogen chloride and dioxin will be produced. If there is no major breakthrough in the disposal technology of packaging waste, the application prospect of PVDC in packaging is not optimistic

ethylene vinyl alcohol copolymer has the same high oxygen resistance as polyvinylidene chloride. Although its ability to block water vapor is poor, it can be compounded with polyolefins such as polyethylene to produce composite materials with high water vapor barrier. Its molding performance is very excellent. It can be molded and processed by conventional thermoplastic processing technology and equipment, and its environmental adaptability is excellent. It can be recycled by melting granulation, and heat energy can be recovered by incineration. When incineration, only carbon dioxide and water are produced without any substances harmful to human health and the natural environment. Therefore, as soon as it comes out, It is considered to be one of the most promising packaging materials. However, due to its high price, its application is greatly limited. Although the progress of coextrusion process and equipment in recent years has reduced the barrier layer of 1. Quality in composite materials to 5%-15% of the total thickness, creating better conditions for the promotion and application of ethylene vinyl alcohol copolymer packaging materials, its application is still limited to those occasions with high added value and its packaging materials are not competent. The large-scale application of ethylene vinyl alcohol copolymers is still due to the substantial reduction in its cost

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