Application of the hottest biaxial tensile nylon f

Application of biaxially stretched nylon film (BOPA) in the field of packaging

Abstract: the requirements of packaging materials and the characteristics, application and processing technology of the "up" or "down" switch (BOPA) on the machine table of biaxially stretched nylon film are introduced, and the domestic current situation is briefly summarized. Key words: nylon membrane; packing; Biaxial tension

0 preface packaging is an important part of commodity economy and an important field of plastic application. With the continuous development of packaging industry, technological progress and the increasing improvement of people's living standards, people have higher and higher requirements for the quality of life. With the increase of trade with foreign countries, packaging is more and more subject to high and strict requirements, mainly including high strength, good toughness, low density, excellent oil and chemical resistance, easy molding, high barrier to oxygen, carbon dioxide and other gases, low cost, no pollution to the contents, and compliance with the requirements of environmental protection. Biaxially Stretched Nylon film has the characteristics of high strength and good barrier, and occupies a high position in the field of packaging (especially in the field of food packaging). 1. The principle of selecting plastics for packaging there are many kinds of plastics that can be used for packaging. How can we choose the most suitable materials? Generally, there are the following principles: 1.1 under the environmental conditions of packaging, storage and transportation, plastic materials shall be selected according to the requirements of protection function. The application of carbon fiber composite technology provides the best choice for automobile lightweight. The protection function of packaging materials for commodities is its most basic function. Therefore, plastic packaging materials must have corresponding characteristics: sufficient mechanical properties (such as tensile strength, impact strength, rigidity, toughness, etc.); Good dimensional stability; Good temperature resistance, oil resistance and acid resistance are the alkali and organic solvent resistance of its stiffness based on the deformation caused by its load; Preserve fragrance, freshness and taste; It has good barrier to O2, N2, CO2 and moisture, and is resistant to ultraviolet rays. 1.2 requirements of the items in the package on the shape of plastic packaging products. The items in the packaging products have different shapes. When selecting the packaging materials, we should pay full attention to the shape characteristics of the plastic, which can meet the requirements of the molding process and packaging assembly line, which is not only convenient for transportation, storage, but also convenient for use. 1.3 the display of packaged goods requires plastic materials. Plastic packaging film has a great impact on the display effect of goods and improving customers' desire to buy goods, especially on the packaging of consumer goods. The film is required to have large light transmittance (transparency), low haze, excellent antistatic and printability, so as to decorate the surface of packaging products and improve the competitiveness of goods in the market. 1.4 requirements for cleaning and hygiene on plastic materials. The materials for packaging goods should not contain substances toxic and harmful to human body, and strictly restrict the transfer of additives and pigments in packaging materials to internal goods, which is particularly important for food packaging. 2 characteristics and forming methods of biaxially stretched nylon film (BOPA) 2.1 compared with other films, nylon film has the following outstanding advantages: (1) compared with PE and PP, it has high puncture strength, and its cracking resistance, impact resistance and tensile strength are the best among packaging films. (2) Compared with barrier materials such as EVOH and PVDC, it has the advantages of cost saving and meeting environmental protection requirements, and its oil resistance and gas barrier ability are very strong. Its barrier to O2 and CO2 is about 100 times higher than that of low-density polyethylene, so it is an ideal raw material for food preservation and fragrance preservation. (3) Excellent flexibility, wide temperature resistance range (- ℃), especially suitable for frozen packaging, cooking packaging and vacuum packaging. (4) Good transparency, non-toxic and harmless. 2.2 introduction to biaxial stretching process biaxial stretching refers to the stretching of the extruded sheet in both vertical and horizontal directions under certain temperature conditions and mechanical force, so as to orient the polymer molecules to improve the strength and transparency of the film. Nylon materials suitable for biaxial stretching include nylon 6 and nylon 66. Generally, nylon 6 is the main packaging material. There are two kinds of biaxial drawing process: two-step drawing and synchronous drawing. Among them, synchronous drawing is more technical and has greater significance in industrial production. Two step stretching is also called secondary stretching. Generally, while adding padding, longitudinal stretching is carried out first, and then both sides of the film are clamped with film clips. Transverse stretching is carried out in the stenter, and heat setting is carried out in the stenter after stretching. The advantages of this stretching method are that the product performance is easy to control and the operation is more convenient. After stretching, the necessary heat treatment and cooling treatment can be completed in the same horizontal drawing machine. The production speed is high, up to 350 meters/minute. However, this method will damage the longitudinal orientation of molecules during transverse stretching and heat treatment, so it is difficult to make reinforced films. In addition, because the heat treatment is carried out in the horizontal drawing machine, it is also difficult to make films with zero longitudinal heat shrinkage. At the same time, biaxial stretching method (also known as one-time stretching method or synchronous biaxial stretching) is a method that extrudes plastic sheets in the same stretching machine, and completes longitudinal, transverse stretching, cold and heat treatment to make films at the same time. The plastic film with extremely stable size and smooth surface can be obtained by stretching in this way. This film is superior to the two-step method in terms of mechanical properties and printing properties. After biaxial stretching, due to the orientation of macromolecular chains, the crystallinity increases, its mechanical photon properties are improved, and its barrier to gas is further improved. Comparison of physical properties of untended and Biaxially Stretched Nylon 6 films test methods unit results untended biaxially stretched density gradient method 1.13 1.14 breaking strength astm-882 -1 MD 60--90 220--250 TD 60--90 220--250 breaking elongation astm-882% MD 300--400 90--120 TD 300--400 90--120 impact strength drop impact test method (n.m/mm) 160 100 oxygen permeability astmd-1434 cm3 (m2.24h0.1mpa) -1155 moisture permeability jisi-0208 g. (m2.24h) -1 80--100 20--30 haze astmd-1003% 184 actual use temperature ℃ - further improve water holding capacity and mechanical strength 30 - 3 application of biaxially stretched nylon film in packaging field although biaxially stretched nylon film has many excellent characteristics, it has disadvantages such as poor thermal performance and strong moisture absorption, In practical applications, biaxially stretched nylon film (BOPA) and other plastics (such as PE, PP, pet, aluminum foil, etc.) are generally made into composite films and then used to obtain a reasonable performance/price ratio. Among them, the most representative product is bopa/ldpe composite film. The role of LDPE in the composite film is to improve the heat sealing performance of BOPA film, avoid direct contact with internal items with more water, maintain the barrier performance of BOPA, and reduce the cost at the same time. The performance indicators of bopa/ldpe composite film are shown in the table below: performance indicators of bopa/ldpe composite film and bag project test method indicators class A and class B tensile breaking force/n (longitudinal and transverse) gb13022, sample 15 μ M ≥ 40 ≥ 30 elongation at break/(longitudinal and transverse)/% gb13022 ≥ 35 ≥ 30 right angle tear force (longitudinal and transverse)/n gb/t1130 ≥ 3.5 ≥ 3.0 interlayer peel force/n gb8808 ≥ 2.5 ≥ 2.0 sealing peel force (bag)/n zby28004 ≥ 20 ≥ 15 pendulum impact energy/n gb8809> 0.8> 0.6 oxygen permeability/(ml.m-2) (24h0.1mpa) gb1038 ≤ 50 ≤ 50 water vapor transmission/(g · m-2) 24h gb1038 ≤ 12 ≤ 15 heat resistance sealed into 40 ℃ saturated salt water 80 ℃, 30s no significant deformation, delamination and sealing cracking cold resistance% gb8809 ≥ 60 ≥ 60 oil resistance% gb13022 ≥ 30 ≥ 30 pressure resistance/bag no penetration, no cracking drop resistance/bag no penetration, no cracking

bopa/ldpe composite film bag in food packaging: it can be used for ordinary boiled food packaging (can withstand 80-100 ℃, boiling minutes), vacuum packaging, deoxygenation packaging, gas replacement packaging, etc., mainly used for refined rice, frozen vegetables Packaging of grilled fish slices, beef jerky, ham, soy sauce, fluid soup, etc; Non food: electronic components, integrated circuit wires, cosmetics, lotion, shampoo, etc. BOPA can also be compounded with CPP to form bopa/cpp composite film, which is used as a high-temperature cooking bag (121-135 ℃, boiling for minutes) to package rice and meatballs; Pet/aluminum foil/bopa/cpp can be boiled at 120-135 ℃ for minutes, and has high barrier and shading properties. It can be used for the packaging of coffee, mustard mustard, roast chicken, soy sauce, ribs and other foods. 4 current situation and Prospect of biaxially stretched nylon film (BOPA) at present, China has many composite film production lines, with an annual consumption of nearly 15000 tons of BOPA, which mainly depends on imports. Guangdong Foshan Dongfang packaging materials Co., Ltd. has two production lines, and the output is far from meeting the demand. This year, several production lines in China have signed import contracts, among which Cangzhou Dongsu Group invested heavily to introduce the world's most advanced synchronous stretching production line, with a design annual output of 4500 tons, which is planned to be put into production in September 2005. It is expected that the domestic output will reach 20000 tons in 2006, and the domestic demand will also increase. With the continuous improvement of people's living standards, processed food and sales methods will become more and more popular, and the demand for high-performance composite films will grow at a faster rate. Therefore, biaxially stretched nylon film will have a good development prospect. Reprinted from: flexible packaging