The development of bimodal film resin 7000F

I. Introduction
Bimodal polyethylene molecular weight distribution curves is the two peaks of polyethylene resin, compared with ordinary polyethylene bimodal polyethylene also has excellent mechanical strength and excellent processing performance --- some of them to ensure the high molecular weight The physical and mechanical strength, low molecular weight part of the grease in the resin to improve the processing of products. Such bimodal polyethylene blow molding process through, not only the processing generally better than a single peak molecular weight distribution of polyolefins and easier processing, high yield, low energy consumption; and because of reduction in melt flow disruption, the mechanical properties of the product more stable.

Bimodal resin film of high strength products with high mechanical strength, stiffness and good processing performance (in speed), the requirements can be processed into shock, vibration resistance of large and high mechanical strength of inflatable tubular film, suitable for production of ultra- thin films, shopping bags, waste bags, heavy duty bags, food and sundries and luxury goods packaging, preservation, film, films produced by the proposed paper, and has strong tensile resistance. domestic demand for such products at present mainly rely on imports each year to spend a lot of foreign exchange, in this case, the development of a market gap, plastic processing industry much-needed high-strength, high stiffness, ultra thin polyethylene resin, capture the market, to meet the needs of users, meaning it is extremely significant.

Second, the development process
According to the needs of our customers, on the domestic market to investigate a wide range, visits, learned that Japan's plastics processing industry, high-strength resin film product has a strong interest in a large domestic demand. Therefore, we have organized Research and trial production and on the peaks of high strength resin film production conditions and product quality indicators made many improvements, so that two peaks of high strength resin film product development success.

1, the bimodal resin products of high strength properties of film index
On the development of new products, the product of a scientific basis for development of physical parameters is a very important task to develop the basic physical parameters is reasonable, will directly affect the use of the product performance and technological level will also affect the product trial smooth production work carried out. polyethylene products for different uses have different performance requirements, but the most important thing is to meet the downstream user or processing industry products standards, and we passed on the foreign and domestic other types of similar products device similar products analysis, and extensive consultation with users, with Japan's Mitsui Oil of the data provided on the product's performance indicators and operating conditions of the two peaks re-examine the design of high-strength resin film quality indicators.

2, two peaks of high strength resin film products on the synthesis of
We have adopted a slurry polymerization process, raw materials ethylene and comonomer (propylene or butene -1) with hexane as solvent in the polymerization reactor through the catalyst, polymerization occurs to produce high density polyethylene (referred to as HDPE) products, and bimodal polyethylene resin with high strength film is made up of three basic physical properties of the resin melt flow rate --- (MFR), density (D), molecular weight distribution (NNI) of the decision, these properties are polymerization reactor operating conditions to control the other good additives in the formulation of the resin during processing and use of the basic guarantee of stability.

2.1 Production
Molecular weight distribution resin polymerization reactor by changing the connection of two way control. Polymerization still has three connections: parallel A, B and series produced in parallel. Parallel A, B in parallel produced the width of narrow molecular weight distribution and secondary products , in series production of a wide molecular weight distribution of products. Therefore, the bimodal high density polyethylene resin produced in series production.

The first production of the high MFR polymer reactor slurry of polyethylene, the flash again after the second polymerization reactor by adding ethylene and comonomer, under the control of the hydrogen concentration, re-growth and chain transfer, production of lower MFR polyethylene slurry, and then flash, and removal of unreacted hydrogen and ethylene, and then by separation, drying, filling plus additives, granulation, mixing only after the final product.

2.2 the two reaction temperature of polymerization reactor
Promote the reaction temperature is one of the engines, the reaction temperature on the reaction speed of the level plays an important role, but also affects the growth of molecular chains, thus affecting the molecular structure. Bimodal high density polyethylene product is by no means simple mixing of two molecular weight polyethylene, but its special molecular structure of the decision, the production of this structure with the two autoclave reaction temperature and reaction between the two reactor has a lot to the temperature gradient, so determine a reasonable reaction temperature is very important. According to series production, to determine the two reactor temperature. reposted elsewhere in the Research Papers Download http://www.hi138.com 2.3 catalyst concentration of the two reactor
Polymerizer concentration of catalyst is not only used to control the speed of response, more important for regulating the molecular weight. The higher the catalyst concentration, reaction speed of the faster growth process chain also Zhongbao together the faster the smaller the molecular weight also , we can ensure that some low molecular weight and the proportion of high molecular weight, so that the behavior of products with a bimodal distribution, but only one of its necessary conditions.

2.4 The two reactor feed ratio of ethylene
Two reactor of ethylene feed ratio is a very important parameter, which is to determine the proportion of high and low molecular weight and molecular weight distribution of some of the main parameters of the state, the processing performance of the products have a great impact, not only to design a perfectly reasonable, and To control is very stable. Choose a good feed ratio is a difficult thing, that is to have a theoretical analysis, but also a practical test of actual production experience with devices, small aggregates through multiple tests, before deciding the final two reactor ethylene feed ratio.

2.5 the two melt flow rate of slurry reactor (MFR) of
Melt flow rate is an indirect characterization of molecular weight, melt flow rate is larger, the smaller molecular weight, melt flow rate the smaller the molecular weight. In addition, grades in series, the first polymer melt flow rate of reactor size of the molecular weight distribution of products have a greater impact, and the second melt flow rate polymerization reactor the size of the products have a greater impact strength, so the two selected reactor slurry melt flow rate is reasonable, in determining whether the product has a bimodal feature of great significance, is a very important control indicator. According to different uses and characteristics of the product to determine the melt flow rate of the two reactor (MFR).

Third, evaluation of product processing
Using RZ-200 catalyst Mitsui trial production of bimodal high-strength resin for high strength and stiffness of membrane micro-film materials, plastic processing by several manufacturers and the Japanese Mitsui Petrochemical processing application tests, test results are as follows:
1, the test manufacturer's test results indicate that two peaks of high intensity physical properties of resin films are entirely meet the design requirements.

2, two peaks of high strength resin film product has a high impact strength, mechanical strength and stiffness and other characteristics, has good processing performance. Processed using the resin film, good film, to be strong on paper, feel good. in a stable condition, the stability of its bubble-type, film thickness uniformity, good transparency, tensile properties and tear strength, particularly its excellent print performance and sealing performance. The property index over the domestic product similar products, similar products meet international standards.

IV Conclusion
Bimodal resin with high strength film, inspection and processing by testing a number of indicators show that two peaks of high intensity grade resin film is an excellent micro-thin film resin, can replace imported HDPE7000F resin, while the design and production process , give full consideration to the domestic production status, so our bimodal resin material of high strength film processing equipment more suited to domestic conditions.

1, two peaks of high intensity HDPE film resin products in the device, the performance index of products fully meet the design values. The results indicated: two peaks of high strength resin membrane properties of three basic indicators: melt flow rate ( MFR), density (D), molecular weight distribution (NNI) is designed to be accurate, aggregation design is reasonable operating conditions.

2, the bimodal resin products of high strength film processing tests showed that the film blowing, high strength, high temperature performance, product appearance, all reached the requirements of the fish eye.

3, the trial production period in the case of stable quality of raw materials, the use of the RZ200 catalysts high activity and good hydrogen response characteristics of the slurry during the trial production of the melt flow rate control stability, and product melt flow rate of particles also controls the target range.

4, two peaks of high strength resin film of the quality products of other performance indicators, such as tensile strength, elongation at break of the product and other indicators have reached the specified value.

5, using a new catalyst RZ-200 successful production of bimodal high-strength resin film products, an increase of the plastic varieties I plant to broaden the market for polyethylene resin, with significant social and economic benefits.

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