Production status of BOPP film and application of

Production status of BOPP film and application of special materials in China

BOPP (biaxially oriented polypropylene) film has high strength, high gas resistance, good printing performance and tear resistance. It is the most consumed variety in PP film products and is also the most widely used. Due to the large profit space and rapid demand growth of BOPP film in previous years, BOPP film production lines in various parts of China have rushed into mass action since 2000, resulting in serious overcapacity, fierce market competition and benefit decline. Since 2003, the sales price of BOPP film in China has decreased by 23%, which has been oversupplied, and the profits of most production enterprises have declined. At present, China has introduced 152 biaxially oriented BOPP film production lines and 89 production enterprises

among them, a total of 73 production lines from Bruckner company of Germany were introduced, accounting for 48% of the total; Introduce 45 production lines from Mitsubishi Heavy Industries of Japan, accounting for 2916%; 16 lines of French DMT company were introduced, accounting for 1015%. The production lines introduced from the above three companies account for 90% of the total. With so many production lines put into operation, the competition is more intense, and the demand for domestic BOPP raw materials is also increasing year by year

according to the Research Report of British PC I film consulting company, from 2003 to 2005, China's new PP film production capacity accounted for 50% of the world's total planned new capacity in the same period, with an average annual growth rate of about 10%. In the next two years, China's BOPP film production capacity will increase from the current 1.8 million tons/year to 2million tons/year, and its share in the world's total production capacity will rise from 23% to 29%, surpassing Europe and ranking first in the world [1]

although BOPP film in China has developed rapidly, there is still a certain gap compared with foreign countries in terms of scale and variety. For example, ExxonMobil BOPP film has an annual output of more than 2million tons, nearly 40 varieties, and a wide range of applications. Domestic BOPP film has a single variety, small scale and high cost, so there are still a considerable number of BOPP film products imported from abroad. Although China's BOPP plants have also launched some new products in recent years, such as BOPP color printing positioning anti-counterfeiting cigarette packaging film, BOPP ultra-low temperature heat sealing cigarette strip packaging film, BOPP anti-wear flower cigarette packaging film launched by Jiangsu Zhongda Group, it is necessary to strengthen product innovation and gradually narrow the quality gap with foreign products. In this regard, industry experts believe that in addition to strengthening management, reducing costs and improving quality, enterprises should also strive to develop new products, develop and produce smoke film, extinction film, pearlescent film, aluminized film, antibacterial film and other multi-functional special films, and devote themselves to exploring foreign markets, which is a new challenge for resin and film production enterprises

1 production status and product consumption structure of BOPP film in China

1 1 overview of BOPP film production in China and major manufacturers

as of July 2004, the national BOPP production capacity has reached 1.8 million tons/year. At the initial stage, the BOPP equipment introduced is basically a single-layer extrusion production line, with a drawing speed of 120 ~ 180 meters/min, a width of 312 ~ 4 meters, and a single line production capacity of 3000 ~ 5000 tons/year. With the development of technology, all the imported equipment in recent years are 3-5-layer extrusion production lines, with the highest drawing speed of 400-500 meters/minute, width of 8-10 meters, and the maximum single line production capacity of 2.15 million tons/year, which is basically consistent with the international level. For example, the equipment introduced by Anhui Guofeng Film Co., Ltd. has a width of more than 10 meters and a stretching speed of more than 500 meters/minute. It is the most advanced BOPP film production device in the world today. China's BOPP film manufacturers are mainly concentrated in South and East China, while the northwest is almost blank. Zhejiang, Jiangsu and Guangdong have the largest production capacity, accounting for 70% of China's total production capacity. Among them, the production capacity of Zhejiang and Jiangsu provinces is 44.18 million tons/year and 42.14 million tons/year respectively, ranking first and second in the country respectively. The three major business groups of Honeywell have settled in Guangdong Province, China, with 41.134 million tons/year, ranking third. Jiangsu Jiangyin Zhongda New Materials International Trade Co., Ltd. has a BOPP film production capacity of 150000 tons/year, and its production scale ranks first among BOPP production enterprises in China. By 2004, there were more than 10 enterprises with a production capacity of more than 50000 tons/year, and some manufacturers with large production scale are shown in Table 1

Table 1 some manufacturers with large scale of BOPP film production in China 10000 tons/year

production capacity of manufacturers

Jiangsu Jiangyin Zhongda Group 15 0

Guangzhou Hongming group 1115

Guangdong Foshan Oriental Group 11 0

Zhongshan Yongning company 512

Anhui Guofeng company 413

Shunde degan group 410

Baoshuo middle class group 317

Yunnan Hongta Group 312

1.2 China's BOPP product consumption structure

BOPP can be divided into optical film, smoke film, electrical film, pearlescent film, etc. according to its purpose. Due to the rise in the price of raw materials in 2004, the cost of packaging products increased, making packaging film products flat or loss. Therefore, some manufacturers of biaxially stretched films adjust their product structure, focus on pollution-free and low noise, and develop special films, such as ultra-thin films, smoke films, electrical films, high stiffness films, high permeability films, pearlescent films, etc. In 2004, the output of BOPP film in China was 1.2 million tons, including 98.14 million tons of ordinary light film, accounting for about 82%; 8.14 million tons of smoke film, accounting for about 7%; 60000 tons of pearlescent film, accounting for about 5%; 2.14 million tons of electrical film, accounting for about 2%; Other membranes are 4.18 million tons, accounting for about 4%

2 can start from one production line. Production and application of BOPP special materials in China

2 1. Performance requirements for BOPP special resin

BOPP film can be divided into many categories according to performance and use. In general, the following requirements are for the performance of BOPP film special materials. 1) High molecular weight PP is used as raw material to produce BOPP film, but high molecular weight will make high-speed processing difficult. Generally speaking, the melt flow index of common membrane is required to be 2 ~ 3 G/10 minutes, and the melt flow index of capacitive membrane is required to be 3 ~ 4 g/10 minutes

2) in order to ensure the film-forming rate of raw materials, PP with low crystallinity must be selected as raw materials. Therefore, the isotacticity of PP resin should be controlled within 95% ~ 9615%

3) the less metal ion impurities in BOPP film, the higher its electrical insulation performance, so PP with very low ash content must be used as raw material. For the raw material of capacitance film, the ash content should be less than 50 ppm, preferably less than 35 ppm; The ash content of BOPP raw materials for the production of ordinary films and coextruded films should generally be less than 200 ppm, preferably less than 150 ppm

4) BOPP film requires high mechanical strength, so there are corresponding requirements for its raw materials. It is generally stipulated that the tensile strength of PP Homopolymer should be greater than 32Mpa, the bending modulus should be greater than 140MPa, and the impact strength of cantilever beam should be greater than 42 joules/meter. For random copolymers, the tensile strength should be greater than 30MPa, the bending modulus should be greater than 140MPa, and the cantilever impact strength should be greater than 30 joules/meter

5) when PP resin is used to produce ordinary film, the light transmittance of the film product should be greater than 90%, and the haze should be less than 115%. For coextrusion package cuts and cuts, the film and smoke film shall be packed after aging, and the light transmittance shall be greater than 75% - 80%, and the haze shall be less than 210% - 310%

6) when BOPP smoke film and pearlescent film are used as packaging materials, the heat sealing strength of the film is required to be greater than 20 N/mm, so three-layer coextrusion is used for film production, and the outer two layers are random copolymer PP raw materials with ethylene content of 3 m% ~ 5 M%

7) in order to reduce fish eyes, in addition to strictly controlling the indicators in the production of BOPP film, it is more important to strictly control the process parameters for the production of BOPP film special materials to avoid producing more gel particles. Qualified BOPP film products require that the particles with 012 ~ 017mm fish eye should be less than 300/m2, and the particles with 017 ~ 115 mm should be less than 5/m2

8) appropriate antioxidants and auxiliary antioxidants should be added to the special materials for BOPP film to make PP have good thermal stability. Some films with special requirements should also be added with additives that meet the requirements [2]

2. 2 situation of different kinds of BOPP film special materials

at present, there are three kinds of BOPP special resins used in the market. The first kind is polypropylene suitable for medium and low speed BOPP extrusion production lines; The second is polypropylene suitable for high-speed extrusion production line; The third kind of resin is polypropylene suitable for high straightness smoke film. See Table 2 for different types of BOPP film special materials

2. 2.1 medium and low speed BOPP film special material

based on the analysis of the current domestic market research results, almost all domestic continuous process PP devices are developing and producing BOPP film special material. From the perspective of market application, the products of Yanshan Petrochemical, Qilu Petrochemical and Shanghai Petrochemical with large output are relatively good in quality. At present, BOPP film resin produced in China mainly belongs to the first category of products. In 2004, BOPP films with line speed of 280 meters/minute and below basically used domestic raw materials, accounting for about 70% of the market demand. The brands with more materials are mainly: Yangzi Petrochemical F1002B (where B is the addition of opening agent), Qilu Petrochemical f680, T36F, Jinan Petrochemical T36F, Daqing T36F, Jiujiang Petrochemical T36F, etc

Table 2 special materials for BOPP film of different types

application raw material performance requirements main brands

medium and low speed products MFR requirements fluctuation range 011, isotacticity 95% ～ 96%, ash

controlled in hundreds of PPM

Yangzi Petrochemical F1002B, Qilu Petrochemical t680, T36F, Daqing Petrochemical, Fushun Petrochemical T38F,

Jiujiang petrochemical, Jingmen Petrochemical T36F, North China Petrochemical Company (Renqiu) li28f

high speed membrane meets the continuous membrane of high-speed production, Low ash content, slightly wider molecular weight distribution, Shanghai Petrochemical f280s

high straightness and isotacticity of smoke film, Singapore TPC fs300e3, American Arco 03zo, Formosa Yongjia 2020s, Egypt

Kesen pp4792, Basel hp521j, hp425j, Japan exiguang f300p

high transparency film, adding nucleating agent, Mitsui chemical 113, 132

electrical film has less impurities and low ash, The development of BOPP film special materials in China is generally improved on the basis of imported brands. The BOPP film special material T36F developed and produced by Qilu Petrochemical Company is one of the best BOPP special materials in China. It adopts the Spheripol technology of American HIMONT company, which is a liquid-phase bulk polymerization process. The product has been sold all over the country, and its overall performance is comparable to that of foreign products. T36F has a film-forming linear speed of 180 meters/minute and a film-forming rate of 97%. Guangzhou Petrochemical Company once used T36F produced by Qilu Petrochemical Company to produce 20 micron optical film, creating a record of 252 hours of continuous film, and the quality has reached the international standard [3]

t36f can produce light film, pearlescent film and double-sided vacuum aluminum plating with different thickness on high-speed and low-speed production lines according to the different requirements of users. Compared with imported raw material products, it has the advantages of small static electricity, low haze, small modulus, small tolerance and so on. At present, the annual output is about 40000 tons. See Table 3 for the main performance indexes of T36F

Table 3 Qilu Petrochemical BOPP (T36F) technical parameters

project quality index test method

melt flow rate (g/10 min) 2 ~ 315 GB/t 3682

isotacticity,% ≥ 95 GB/t 2412

elongation at break,% ≥ 500 GB/t 1040

powder ash,% ≤ 0103 GB/t 9345

tensile yield strength (MPA) ≥ 27 GB/t 1040

density (kg/m3) 900 ~ 919 0

cleanliness, Color particles (PCs./kg) 0 ~ 5