Metallocene polyethylene(mPE) is a kind of polyethylene resin synthesised on the basis of metallocene catalysts, which is a very important technological innovation in the polyolefin industry in recent years. Product types mainly include metallocene low density high pressure polyethylene, metallocene high density low pressure polyethylene and metallocene linear low density polyethylene. Metallocene polyethylene has been widely used in multilayer co-extrusion blow moulding process by virtue of its unique physical properties and processing performance, and is favoured by domestic and foreign packaging and printing enterprises.
Properties of metallocene polyethylene
1. Metallocene polyethylene has better elongation at break than conventional polyethylene. Metallocene polyethylene has better impact strength due to its higher molecular weight and denser distribution than conventional polyethylene.
2. Lower heat sealing temperature and higher heat sealing strength.
3. Better transparency and lower haze value.
Metallocene polyethylene film applications
1. Food packaging
Metallocene polyethylene film can be laminated with BOPET, BOPP, BOPA and other films, especially suitable for packaging meat food, convenience food, frozen food and other products.
2. Agricultural products packaging
Blow-moulded metallocene polyethylene film made of different process formulations for water vapour barrier is good, while the oxygen permeability is high, this feature makes it particularly suitable for fresh fruit and vegetable packaging. In addition, metallocene polyethylene blown film has the characteristics of high strength, anti-fogging, anti-dripping, ageing resistance and good transparency.
3. Heavy bags
Heavy duty bags are mainly used for packaging plastic raw materials, fertilisers, feed, rice and grains. The emergence of metallocene polyethylene, heavy-duty bags can make the sealing performance, moisture resistance, waterproof performance, anti-aging performance is more superior, with high temperatures do not soften the deformation, the cold does not brittle broken rupture of the advantages.
The addition of metallocenes in film processing improves the tensile strength and quality of the film, but there are also some challenges in processing, such as the high viscosity of metallocenes affecting the processing fluidity and the phenomenon of melt breakage of the product in the extrusion process.
Reasons for melt fracture of metallocene polyethylene in film processing may include the following:
1. high viscosity: metallocene polyethylene has a high melt viscosity, which can lead to melt fracture during extrusion as the melt is subjected to high shear forces as it passes through the orifice die.
2. Inadequate temperature control: If the process temperature is too high or uneven, this may result in the material being over-melted in some areas while remaining partially cured in others, and this uneven melt state may lead to fracture of the melt surface.
3. Shear stress: In the extrusion process, the melt may be subjected to excessive shear stress at the muzzle die, especially if the muzzle die is not properly designed or the processing speed is too fast, this high shear stress may lead to melt fracture.
4. Additives or masterbatches: Additives or masterbatches added during processing that are not uniformly dispersed may also affect the flow characteristics of the melt, leading to melt fracture.
SILIKE PFAS-free PPA SILIMER 9300，Improved metallocene polyethylene melt fracture
SILIMER series products are PFAS-free polymer processing aids (PPA) which were researched and developed by Chengdu Silike. This series of products is Pure modified Copolysiloxane, with properties of polysiloxane and the polar effect of the modified group.
SILIMER-9300 is a silicone additive containing polar functional groups, used in PE, PP and other plastic and rubber products, can significantly improve processing and release, reduce die build-up and improve melt fracture problems, so that the product reduction is better.
At the same time, SILIMER 9300 has a special structure, good compatibility with the matrix resin, no precipitation, no impact on the appearance of the product and surface treatment. It is recommended to be diluted into a certain content masterbatch first, then used in polyolefin polymers, adding it in moderation can be very effective.
Add SILIMER 9300 to the process, the melting flow, processability, and lubricity of the resin can effectively improved as well as eliminate melt fracture, greater wear resistance, smaller friction coefficient, extend equipment cleaning cycle, shorten downtime, and higher output and a better products surface, a perfect choice to replace pure fluorine-based PPA.
Improvement of metallocene melt fracture.
Contact us Tel: +86-28-83625089 or via email: amy.wang@silike.cn.
website:www.siliketech.com to learn more.
Post time: Jul-31-2024
