With the development of China's packaging industry, China's packaging has developed from simple paper packaging to single-layer plastic film packaging, to the wide use of composite materials. The composite film can keep moisture, keep fragrance, beautiful, keep fresh, avoid light, prevent penetration, prolong shelf life and so on.
Experts of China Packaging Network pointed out that composite materials are two or more materials, which are combined by one or more composite processes to form a certain functional composite material. Generally, it can be divided into base layer, functional layer and heat seal layer. The base mainly plays the role of beauty, printing and moisture resistance. It has good thermal barrier properties such as PVA, LDPE, LDPE, LDPE, LDPE, etc.
The following China Packaging Network Editor on the composite flexible packaging material development, development and status quo for you to make a little brief.
1. LDPE, LLDPE resin and membrane
China's composite film began in the late 1970s. From the early 1980s to the mid-term, China began to introduce some extruders, film blowing machines and printing machines to produce simple two-layer or multi-layer composite materials. Such as extruded BOPP / PE, paper / PE, PP / PE; dry composite BOPP / PE, PET / PE, BOPP / Al / PE, PET / Al / PE, etc. In order to enhance the strength and stiffness, a certain proportion of LLDPE is often blended into LDPE resin and membrane. Mainly used in instant noodles, biscuits, mustard and other food packaging. General coating grade LDPE resins include: ic7a, l420, 19n430, 7500, etc.; blown LDPE resins include Q200, q281, f210-6, 0274, etc.; LLDPE resins include 218w, 218f, fd21h, etc.
2. CPP membrane and CPE membrane

From the late 1980s to the early 1990s, with the introduction of a new generation of flexible packaging equipment and tape casting equipment, the scope of packaging contents was further expanded. Some puffed food, cereal and other packaging bags required higher transparency, while boiling, high-temperature sterilization products were successively launched. The requirements for packaging materials were also correspondingly improved. The inner layer materials mainly composed of LDPE and LLDPE could not meet the requirements Requirements for the above products. The products produced by tape casting have good heat sealing property. CPP with oil resistance, transparency, aroma retention, special low moisture heat sealing and high temperature cooking properties has been widely used in packaging. On this basis, the development of aluminum plating CPP, because of its metal luster, beautiful, barrier performance is also rapidly used. The CPE film produced by tape casting is also being used because of its unidirectional easy tearing, low temperature heat sealing and good transparency.

3. MLLDPE resin
With the continuous development and change of packaging market, there are more and more special requirements for packaging. The metallocene polyethylene (mLLDPE) was polymerized by Dow Chemical Company in USA by metallocene catalysis. Such as apfinity, pop1880, 1881, 1840, 1450 and other resins. Then Exxon of the United States, Mitsui of Japan and Philips of the United States also successively produced mLLDPE. For example, Exxon's ex-ceed350d60, 350d65, Mitsui Petrochemical's e-volume sp0540, sp2520, Philips mpact d143, d139, etc. MLLDPE can be mixed with LDPE and LLDPE, and the mixing ratio can be from 20% to 70%. This kind of film has good tensile strength, impact strength, good transparency, good low temperature heat sealing and anti pollution properties. The composite materials with its inner layer are widely used in frozen and refrigerated food, shampoo, oil, vinegar, soy sauce, detergent, etc. It can solve the packaging speed, broken package, missing package and penetration of the above-mentioned products in the process of packaging production and transportation.
4. Cover film inner layer material
Jelly, juice, yogurt, fruit milk, soup and other liquid packaging cups, bottles, the main materials are HDPE, PP, PS, etc. The cover film of this package should not only consider the shelf life, but also the heat sealing strength between the cover film and the cup, as well as the convenience for consumers -- easy tearing. To achieve this particularity, the inner layer material can only form the interface bonding strength with the cup, but can not completely penetrate and fuse together. Modified EVA resin is generally used. For example, DuPont appeel53007. TOPCO l-3388 of Toyo, lotryl 20mA 08 of France, Japan HIRO.DINE Wt231, etc. Its structure can be: PET / PE / hm, BOPA / PE / hm, PET / VMPET / PE / hm, PET / Al / PE / hm, paper / PE / Al / PE / HM. For the requirement that the cover film and the bottom cup are firmly covered without tearing, the material of the bottom cup is generally required to be the same as that of the inner layer of the cover film, so that the two materials can be completely fused during heat sealing. For example, HDPE cup is made of LDPE or EAA; PP cup is made of CPP film; for PET bottle, we have found a kind of PET film which has been coated and modified as heat sealing layer to seal pesticide PET bottle, and satisfactory results have been obtained.
4. Coextrusion film
The film produced by single layer LDPE or LDPE blended with other resins has single performance, which can not meet the requirements of modern product development for packaging. Therefore, the comprehensive performance of coextrusion film produced by CO extrusion blowing film or co extrusion tape casting equipment is improved. For example, the mechanical strength, heat sealing performance, heat sealing temperature, barrier, opening, anti pollution and other comprehensive properties of the membrane are improved, and its processing cost is reduced, so it is widely used. For example, hot melt adhesive film of H-layer co extrusion blowing film: PE / hm, cable film PE / EAA, mLLDPE low temperature heat sealing film, EVA cover film, antistatic film and smooth film. H-layer co extruded CPP, unmodified PP / heat sealing PP, etc. Three layer, five layer structure of nylon coextrusion film, five layer, seven layer EVOH, PVDC high resistance diaphragm are also developing and widely used.
The development of the inner film of composite flexible packaging materials has developed from LDPE, LLDPE, CPP, mLLDPE to the mass use of coextrusion film, which basically realizes the function and individuation of packaging, and meets the requirements of quality assurance, processing performance, transportation and storage of packaging contents. With the continuous introduction of new materials and the improvement of inner film production technology and equipment, the inner film of composite flexible packaging materials will get rapid development and promote food.
5. Others
With the progress of society and the increasing demand of human beings, various functional and environmental protection packaging films are emerging. For example, the water-soluble polyvinyl alcohol film with environmental safety, complete degradation and good heat sealing performance is under development as well as as as a single-layer packaging material.
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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