Development Of Special Material For Hot Filling Propylene/butyl Copolymer Polypropylene

With the growth of the domestic fast-moving consumer goods market,the demand for hot-filling bottles for beverages such as juice and milk tea continues to rise.Common hot-fill bottles are mostly PET products,and their temperature resistance is lower than70°C.The production cost of PET products that have been shaped by heat treatment is high and the production is difficult.Propylene/1-butylene copolymer has higher heat distortion temperature,better transparency and lower n-hexane precipitation,so it is more suitable for hot filling field.At present,the domestic hot filling special materials include Zhongyuan Petrochemical ethylene/propylene copolymer B10 and Shanghai Petrochemical propylene/butylene copolymer E980BHF.The annual output is 3,000 tons and 10,000 tons respectively,and the annual demand is 30,000 tons,which cannot meet the market demand of 30,000 tons/yearBased on the investigation of the domestic canned beverage market,this paper comprehensively considers the performance requirements of the hot-filling process and the injection-stretch-blowing process for the special material,and formulates the key technical indicators of the special material for propylene/butylene copolymerization.Relying on the 550,000-ton/year Innovene gas-phase polymerization unit of Dushanzi Petrochemical,the polypropylene resin PB13HF for hot filling was developed.Through the results,performance analysis and nucleating agent modification,the performance was finally optimized.The specific research is as follows:(1)The key technical indicators of the special material for propylene/1-butylene copolymerization are formulated.The specific requirements are:melt mass flow rate MFR=8～12.0 g/10 min,tensile yield strength≥28.0 MPa,and impact strength of simply supported beam at room temperature≥4.0 k J/m~2,flexural modulus≥1100 MPa,load deformation temperature>72.0℃.On the Innovene gas phase process plant,a total of340 tons of PB13HF were produced.(2)The microstructure and macroscopic properties of the trial-produced PB13HF were analyzed,and compared with the similar materials E980BHF and B10 in the market.The flexural modulus of PB13HF is 1012 MPa,the impact strength of simply supported beam at room temperature is 3.4 k J/m~2,and the thermal deformation temperature under load is 62.0°C,all of which do not meet the pre-required index requirements,and have a big gap with similar materials E980BHF and B10.Microstructure analysis found that the crystallization temperature of PB13HF was low,the rate was slow,and the final spherulite size was large,which affected the mechanical properties of the resin.(3)Study the influence of nucleating agent types on the structure and properties of PB13HF,and finally complete the optimization of properties.Among them,nucleating agent A can improve the rigidity and toughness of PB13HF at the same time.When the addition amount of nucleating agent A is 0.06 wt%,the grains are refined to a great extent.The flexural modulus of PB13HF reaches 1184 MPa,and the impact strength reaches 4.6k J/m~2,the thermal deformation temperature under load is 87.0℃,which meets the index requirements.Using nucleating agent A with an addition amount of 0.06 wt%as the final modified formula,the performance optimization of PB13HF was completed,and 409 t of qualified products were finally produced.The product has high forming rate and low preform haze,which can meet the needs of the market in the field of hot filling.