Sinopec has successfully developed domestic production technology of melt blown polypropylene.
However, in recent years, with improvement of meltblown technology and expansion of domestic market demand, problem of insufficient production capacity caused by technical limitations of traditional method of decomposition of special meltblown materials still seriously limits production of meltblown nonwovens.
After nearly 7 years of continuous research by R&D team, Yanshan Petrochemical has successfully produced metallocene polypropylene products, successfully filling gap in continuous production of metallocene polypropylene in country.
The melt blown material will have residual odor. Sinopec has taken lead in development of metallocene melt blown polypropylene, which can change situation when domestic high quality melt blown materials are controlled by foreign countries.
Sinopec Yanshan Petrochemical applied new technology of hydrogen modulation method to directly produce special materials by melt blown on PP equipment, and successfully tested it on its newly built melt blown fabric production line, successfully producing melt blown fabric. .
According to introduction, new hydrogen adjustment method technology simplifies production procedures and introduces large-scale production. The daily output of one set of equipment can reach 200-250 tons, which greatly improves production efficiency.
This technology has doubled production capacity of Yanshan Petrochemical's blown materials, fully revealing its special advantages in entire blown fabric production chain, not only ensuring self-sufficiency of raw materials, but also directly supplying to market.
Currently, meltblown production in my country can be divided into three types: hydrogen regulation method, peroxide decomposition method, and metallocene catalysis method.
01 Peroxide decomposition
First, low melt index base resin is produced, then organic peroxide is added to decompose polypropylene into low molecular weight segments in extrusion granulation process, so that melt mass flow rate (MFR) increases accordingly, is one method. commonly used in production of high melting point polypropylene at home and abroad, also known as controlled decomposition method.
02 Hydrogen adjustment method
Using a new catalyst system and an improved polymerization process known as Hydrogen Control Method.
During polymerization of propylene monomers, additional molecular weight regulators (hydrogen) are added to macromolecular chains of polypropylene to stop polymerization reaction and control growth of polypropylene molecular chains, thereby ensuring higher fluidity. This method is a hot spot of process research at home and abroad.
03 metalocene catalysis
It is a process using metallocene catalyst to produce polypropylene products, which can be widely used in spinning, curing, food packaging and other fields.
Comparison of pros and cons
The method of regulating hydrogen is to stop activity of reaction by increasing proportion of hydrogen gas. It uses starvation method without introduction of other impurities. The product has a great smell and is more environmentally friendly.
The material blown from melt by hydrogen modulation has better color and stability, and crystallization temperature and melting temperature are respectively lower, yield is larger, productivity is higher, and production time is shorter.
The controlled degradation method is a kind of swelling method. The free radicals generated by heating peroxide will preferentially attack high molecular weight molecular chains, so that overall molecular weight distribution is narrowed and product uniformity is good.
However, all types of organic peroxides currently in use have a strong, pungent odor. Remaining in product, they cause an unpleasant smell of product. At same time, low molecular weight aldehydes, various odorous substances such as ketones, quinones, esters, etc., cause odor defects and yellowing of color.
Compared to traditional catalytic systems, metallocene polypropylene products have more regular molecular chain segments, better product appearance, better clarity, and lower volatiles and deposits.
So, in general, hydrogen modulation method > metallocene catalysis method > peroxide decomposition method.
Please decide if following statements are true/false?
Click ? below to view answer
The melt-blown hydrogenated fabric is of high purity, high strength and no peculiar smell. The manufactured KN95 mask is more comfortable to wear and has good market prospects.
Answer: It must be a metallocene.
The most effective way to control residue is to control amount of peroxide added.
Answer: You should control time of stay.
The heating efficiency of filter should be lower than that of extruder, which can reduce holding time.
Answer: Think again.
The distance between holes should not be too large so that materials do not stick together at exit.
Answer: distance between holes doesn't really matter.
Source: Chain Plastic Network