Compared with the glass and Tetra - pac, PP rigid package has a unique advantage, they can be used for non oxygen sensitive drinks package
, suitable for filling of cold and hot filling process.Drinking water, milk, fresh fruit juice with cold filling process, grain and raw materials and various flavor drinking water is generally USES the hot filling (up to 98 ℃) process.30% lower than that of PET, PP density and bottle manufacturing process is simple, so the packing cost is low.If cap and bottle are using PP raw materials, but also has the characteristics of easy recycling.
PP drawback is that toughness is low, prone to brittle fracture;PP Tg is quite high, low temperature resistant performance is poor, prone to stress cracking, surface resistance is big, easy to generate static electricity, low surface tension, polarity, printing after bad;PP in solvent such as toluene and ethyl acetate with high adsorption (dissolved), with its as a packaging material, which have thin = organic solvent residue are relatively high.Aimed at these shortcomings of PP, people have made many modification study on PP, PP performance improving.These studies include increasing the stiffness of PP for packaging reduction possible;To improve the toughness and decrease the PP city with low temperature limit;Lower processing temperature, improve the melt flow rate, improve the processing performance: smooth agent, reduce the friction factor, suitable for the requirements of automatic packaging production line;Adding antistatic agent, and improve the antistatic performance of the means of which two are generally add fertilizer and then melt blending, also has the copolymerization method of preparing high performance PP resin:
PP335NBNA IPEx developed, for example, high impact PP copolymer, and USES the plus into relevant to improve learning performance, the brand of the PP has good mechanical properties, processability, antistatic properties, injection molding processing, very suitable for fish used in rigid package, high stiffness and high bending strength.
High impact PP copolymer is cap special material (table 3-16).The 100 series of PP homopolymer has different
Melt flow rate, suitable for all kinds of processing technology, performance differences (table 3-17), 101 - SA09 join smooth agent, for example, used in the production of low friction factor of the flexible packaging film;100 - HR25 with high hardness, bending modulus, high heat resistance,
Antistatic and high melt flow rate, processing performance;100 - CA50 and nucleating agent modification, antistatic properties, melt flow rate is high, suitable for high speed machining.