Summary of the hottest plastic flexible packaging

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Summary of plastic flexible packaging materials with the continuous development of science and technology, people have higher and higher requirements for the quality of life. High performance, multi-functional plastic flexible packaging materials are becoming a hot development of packaging materials

1. High barrier plastic packaging materials

high barrier plastic packaging materials are developed with the rapid development of the food industry. They play a role in ensuring the quality, freshness, flavor and prolonging the shelf life of food. There are various technologies for preserving food, such as vacuum packaging, gas replacement packaging, sealed deoxidizer packaging, food drying packaging, sterile filling packaging, cooking packaging, liquid heat filling packaging, etc. Many of these packaging technologies use plastic packaging materials. Although they are required to have a variety of properties, it is important that they all have good barrier properties. The following is an introduction to the barrier materials of various common flexible packaging forms

the common high barrier film materials are as follows:

1.pvdc materials (polyvinylidene chloride)

polyvinylidene chloride (PVDC) resins are often used as composite materials or monomer materials and coextrusion film sheets. They are the most used high barrier packaging materials, of which PVDC coating films are used in particular. The PVDC coating film uses polypropylene (OPP) and polyethylene terephthalate (PET) as the substrate. Because pure PVDC has high softening temperature, close to its decomposition temperature, and poor compatibility with general plasticizers, it is difficult to heat up and directly apply. PVDC films that are actually used and stored in dry and ventilated places are mostly copolymers of vinylidene chloride (VDC) ~n vinyl chloride (VC) and films with excellent barrier properties made by copolymerization with methyl acrylate (HA)

2. nylon packaging materials

nylon packaging materials used to use "nylon 6". But the air tightness of "nylon 6" is not ideal. There is a nylon (mkd6) polycondensated from m-dimethylamine and adipic acid. Its air tightness is 10 times higher than that of "nylon 6". At the same time, it has good transparency and puncture resistance. It is mainly used for high barrier packaging film and soft food packaging with high barrier requirements. Its food hygiene is also approved by FDA. As a thin film, its greatest feature is that its barrier property does not decrease with the rise of humidity. In Europe, as a substitute for PVDC films, MXD6 nylon is used in a large amount due to outstanding environmental protection problems. A new type of film with bi-directional extensibility, which is composed of MXD6 nylon and EVOH, is used as a nylon film with high barrier. The methods of compounding include multilayer compounding and blending and stretching of MXD6 nylon and EVOH

3.evoh materials

evoh has been the most widely used high barrier materials. In addition to the non stretching type, the film types of this material include biaxial stretching type, aluminum evaporation type, adhesive coating type, etc. Biaxial stretching type and heat-resistant type are used for aseptic packaging products. The film made by CO extrusion of eboh resin with polyolefin, nylon and other resins is mainly used for animal product packaging

4. inorganic oxide coated film

PVDC is widely used as a high barrier packaging material. Because its waste will produce HCI during combustion treatment, resulting in environmental pollution, the current trend of being replaced by other packaging materials is to organize the 6th China EU raw materials working group meeting and the meeting of the raw materials working group of the China Russia sub committee of industrial cooperation. For example, the so-called coating film prepared after SiOx (silicon oxide) is coated on the films of other substrates has been paid attention to. In addition to the silicon oxide coating, there are also alumina evaporation films. Its air tightness is the same as that of the silicon oxide coating obtained by the same method

in recent years, the technology of multi-layer compounding, blending, copolymerization and evaporation has developed rapidly. High barrier packaging materials such as multi-layer composites of ethylene vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), polyamine (PA), polyethylene terephthalate (PET) and silicon oxide evaporation films have been further developed, especially the following products: MXD6; Polyamide packaging materials: polyethylene naphthalate (pen): silicon oxide evaporation film, etc

II. New fresh-keeping film

due to the specialization of agricultural production, more and more long-distance transportation, the long-distance transportation of fresh fruits and vegetables, and the improvement of people's requirements for quality of life, there is an increasing demand for fresh-keeping films that can prolong the storage life and shelf life of fresh fruits and vegetables

with the development of food industry and the progress of material science, food packaging materials not only require high gas resistance, but also further require the development of selective permeability. Such selective permeability packaging materials have entered the practical stage abroad, mainly including films with dissolved gas substances, and films with porous zeolite or silica powder, The properties of films were changed by gamma ray irradiation, the dependence of diffusion coefficient on water content, and the introduction of films containing hydroxyl groups and amide groups

in recent years, the preservation technology that has attracted much attention is the combination of microporous or improved film formula structure, improved air conditioning environment (atmosphere) in the packaging bag, and the use of Deaerator and surface quenching hardness of hrc58 (6) 2 to selectively penetrate the film. Among them, the following products will receive greater attention

1. functional fresh-keeping film

Japan launched strong sealing packaging bags,. It is made of a kind of plastic called "qikelun", which has an excellent anti-oxidation effect. It can be used to pack new rice, which has a particularly good fresh-keeping effect. It can keep the color, aroma and taste of rice unchanged for a long time, and the carbon dioxide produced in the bag can also prevent insects and mold

in addition, the fruit fresh-keeping packaging box is also launched. It is to add a layer of polyethylene film on the corrugated paper lining of the corrugated box, and then apply a waterproof wax coating containing a trace of fruit disinfectant to prevent the evaporation of fruit moisture and restrain the British government. At the same time, the British government also announced a strategic system to promote the biological economy to achieve the purpose of fresh-keeping. This kind of packing box can keep the fruit fresh for one month

the American company has launched a new type of fresh-keeping plastic bag for fruits and vegetables, which can prolong the fresh-keeping period of fruits and vegetables and reduce the losses caused by excessive ripening of fruits and vegetables. The packaging bag is made of natural activated clay and polyethylene, which is like a very fine filter screen. The gas and water generated during the ripening process of fruits and vegetables can pass through the packaging bag, which is not easy to breed fungi, thus extending the freshness of fruits and vegetables by more than one time

American companies have developed plastic fresh-keeping bags that can last up to 3 years. This kind of fresh-keeping bag is attached with a layer of plastic film inside the ordinary plastic bag. The film contains oxygen getter, which can absorb the oxygen in the process of food packaging, which makes the microorganisms that cause food decay unable to survive due to lack of oxygen

2. modified atmosphere fresh-keeping bag with silicon window

the modified atmosphere fresh-keeping bag with silicon rubber film of appropriate area is loaded on the plastic film bag. Silicone rubber film can selectively permeate oxygen, carbon dioxide and nitrogen. This kind of silicon window modified atmosphere fresh-keeping bag has achieved good results in fruit storage. Using it, the appropriate silicon window area can be determined under certain storage conditions, and the concentration of oxygen and carbon dioxide in the package can be automatically adjusted to the required level after being closed for a certain time. In general, the large account for storing 1o00kg apples has a silicon window area of 0.6m, which can maintain the oxygen and carbon dioxide at an appropriate level. The excessive carbon dioxide generated by respiration can be discharged through the silicon window. When the oxygen in the bag account is insufficient, it can be penetrated through the silicon window. The key to the silicon window air conditioning technology is to select the silicon window film to determine the silicon window area, suitable storage capacity and storage temperature

III. sterile and antibacterial plastic packaging materials

sterile packaging can maximize the original nutritional components and flavor of food at room temperature without adding preservatives under sterile conditions. It can prolong the shelf life and facilitate transportation and storage. Aseptic packaging is mainly used in food, high seasoning, medicine, cosmetics and other fields. The flexible packaging materials used are paper, plastic, aluminum-plastic composite films, multi-layer co extrusion sterile packaging sheets containing high barrier plastics, etc

antibacterial plastic packaging materials give certain antibacterial properties to plastic packaging materials. Now, a brand-new masterbatch has been developed with silver ions as inorganic antibacterial agents. Silver ions have significant antibacterial effects, which are characterized by long-lasting antibacterial effect, not high due to gasification and migration, and not polluting the environment. The film made from the added silver ion masterbatch (content 1% - 3) or the container with a layer of such film on the surface has been tested. It has been shown that the film containing a silver ion masterbatch can completely kill the bacteria that will cause food poisoning within 1-2 days in the absence of nutrition source. It is widely used in the packaging of cooked meat, aquatic products and liquid food

IV. high heat-resistant plastic packaging materials

heat resistant plastic flexible packaging materials used to be resistant to cooking and sterilization. They meet the packaging requirements for cooking and sterilization. Under the conditions of 120~c, 10-20min cooking and sterilization or heating, there is no obvious change in appearance, shape and quality, and the packaged food will not have container damage, content leakage, secondary microbial pollution, light and heat deterioration during storage. Most cooking bags are made of multi-layer composite cooking films with shading aluminum foil as the middle layer, high barrier plastics PA and pet as the outer layer and heat sealing PE and PP as the inner layer. Some new multilayer composites containing high barrier materials such as EVOH, PVDC, MXD6 and silicon oxide evaporation film are also gradually used

with the increasing popularity of electromagnetic cookers and microwave ovens, there is an increasing demand for packaging containers suitable for electromagnetic cookers and microwave ovens. The requirements for the packaging materials of the electromagnetic cooker and the microwave oven are that the packaging materials are not significantly deformed, damaged and the contents (additives) are not volatile under high temperature. In particular, the heating characteristics of the microwave oven do not allow the packaging materials to contain metal materials, which limits the use of cooking bags with aluminum foil as the middle layer and PE and PP as the inner layer. Therefore, now multi-layer composite materials filled with PP and inorganic materials and packaging containers made of crystalline poly ~ (CPET) sheets are mostly used. New heat-resistant packaging materials with higher temperature resistance, such as polysulfone film, polyetherimide, poly 4-methylpentene (TPX)/paperboard, have also been developed. They can withstand temperatures above 18O ℃, which is enough to meet the requirements of electromagnetic cookers and microwave ovens for packaging materials

v. special functional materials

functional packaging materials: other flexible packaging materials with special functions include hygroscopic, deodorizing, deodorizing, antistatic, antirust, UV blocking, volatile gas release or adsorption, convenience (easy to open and seal) and edible materials. For example, the film developed in recent years by adding iron, ascorbic acid and other compounds or activated carbon, zeolite, etc. to PE, PP and PVC has the effect of removing odor such as ammonia, mercaptan, hydrogen sulfide and dimethylamine. It is suitable for packaging agricultural and sideline products, aquatic products and raw and fresh food with special odor, and will not cross smell. It is also suitable for garbage bags

VI. nanocomposite packaging materials

nanotechnology is a new science and technology emerging in recent years. Polymer based nano packaging materials are the most studied nanocomposite packaging materials

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