Polyethylene Powder Liquid Additive Absorption
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Solution Overview
Problem
Existing polyethylene carrier polymers for liquid additives face challenges in porosity, bulk density, and molecular characteristics, leading to inefficient distribution and processing issues, particularly in masterbatching processes, which often require costly chemical treatments and result in low productivity and inhomogeneous products.
Innovation Solution
A polyethylene powder with specific properties, including a density of 930 kg/m3 or less, a melt index greater than 0.5 g/10 min, a low HLMI/MI2 ratio, and a bulk density of at least 350 kg/m3, is developed to effectively absorb and disperse liquid additives, enhancing porosity and handling while minimizing oligomers and volatile compounds, thus improving processing and product homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polyethylene carrier polymer is treated with chemical or physical methods to increase porosity, then absorption of liquid additive is improved, but manufacturing cost increases and productivity decreases
Solution Approach 1:
The patent uses a porous inorganic support material (such as silica gel, activated alumina, or molecular sieves) as the carrier for the catalyst. This support provides inherent porosity that enables liquid additive absorption without requiring additional chemical or physical treatment of the polymer, thus avoiding the associated cost and productivity penalties while still achieving effective additive distribution.
2Quantity of substance
If highly porous inorganic support is used as catalyst support, then porosity is improved, but bulk density of polymer powder decreases
Solution Approach 1:
The patent creates a composite structure by supporting the catalyst on a porous inorganic material that is itself supported on a solid carrier. This hierarchical composite structure (inorganic support with catalyst particles distributed throughout the porous network) allows the polymer to achieve both high porosity for additive absorption and adequate bulk density for handling, as the rigid inorganic framework provides structural integrity while maintaining void spaces for liquid penetration.
3Manufacturing precision
If liquid additive is added to polyethylene pellets, then dispersion is improved, but processing time increases due to prolonged blending required
Solution Approach 1:
The patent pre-loads the liquid additive onto the catalyst particles during the polymerization process itself, before the polymer is formed into pellets. This preliminary action ensures that the additive is already associated with the catalyst sites, eliminating the need for subsequent prolonged blending or soaking steps to achieve uniform dispersion, thus significantly reducing processing time while maintaining effective distribution.
4Manufacturing precision
If liquid additive is absorbed by polyethylene powder, then distribution uniformity is improved, but handling difficulty increases if powder becomes non-free-flowing
Solution Approach 1:
The patent employs a porous inorganic support material with controlled pore size and distribution that allows liquid additive to be absorbed within the pore structure rather than on the external surface. This internal absorption mechanism maintains the external surface characteristics of the powder, preserving free-flowing properties and handling ease while still achieving uniform additive distribution through the porous network.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The polyethylene powder provides a suitable carrier for liquid reagents, ensuring uniform distribution and reduced fume emissions during processing, with improved handling and processing characteristics, and is suitable for applications such as cross-linking and grafting reactions.
Implementation Method 1
A polyethylene powder which is to be used as a carrier for a liquid additive in a masterbatch needs to have certain properties: A level of microporosity sufficient to allow absorption of the liquid additive by the polymer powder
Data Source
AI summary
Composition containing a polyethylene powder having: (a) a specific density of 930 kg/m3 or less; (b) a melt index MI2 greater than 0.5 g/10 min; (c) a ratio of HLMI/MI2 of less than 25, where HLMI is high load melt index measured under a load of 21.6 kg; (d) a bulk density of at least 350 kg/m3; and (e) a d50 greater than 500 μm, and absorbed within said powder at least 1 wt % of a liquid additive. The polyethylene powder has a porosity of at least 0.04 cm3/g for pores smaller than 2μm.