Ethylene Polymer Composition for Solid Phase Drawing
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Solution Overview
Problem
Ultrahigh molecular weight ethylene polymers are challenging to mold using solid phase drawing methods due to low strength of the resultant molded articles, as they require high crystallinity and specific surface features for improved drawability and adhesion between polymer particles.
Innovation Solution
An ethylene polymer composition with a specific molecular weight range (30 dL/g to 50 dL/g) is achieved through a two-stage polymerization process, combining polymers with intrinsic viscosities of 2-20 dL/g and 35-50 dL/g, and a high degree of crystallinity, using a solid titanium catalyst and organometallic compounds, to enhance drawability and tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrahigh molecular weight ethylene polymer is used for solid phase drawing molding, then molecular weight and inherent strength are improved, but drawability and adhesion between particles deteriorate
Solution Approach 1:
The polymer is segmented into two distinct components with different molecular weights: component (a) with intrinsic viscosity of 2-20 dL/g serving as a matrix, and component (b) with intrinsic viscosity of 35-50 dL/g providing reinforcement. This segmentation allows each component to fulfill different functional requirements - the lower molecular weight component ensures processability and particle adhesion, while the higher molecular weight component provides inherent strength
Solution Approach 2:
The invention changes the molecular weight parameter by creating a bimodal distribution rather than using a single molecular weight. The specific intrinsic viscosity ranges (2-20 dL/g for component a, 35-50 dL/g for component b) and their mass ratio (5/95 to 50/50) are optimized parameters that simultaneously achieve good drawability and high inherent strength in the molded article
2Shape
If polymer particles with less surface concavity and convexity are used for solid phase drawing molding, then surface smoothness is improved, but contact points and adhesion between particles deteriorate
Solution Approach 1:
The invention applies local quality by creating surface concavity and convexity specifically on the particle surfaces while maintaining smooth internal structure. This localized surface roughness increases contact points between particles during molding, enhancing adhesion without affecting the overall spherical shape and internal homogeneity of the particles
3Stability of the object's composition
If ethylene polymer with high degree of crystallinity is used, then heat of fusion and structural stability are improved, but processability and drawability deteriorate
Solution Approach 1:
The invention creates a composite material system where component (a) with moderate crystallinity serves as a processable matrix, and component (b) with high crystallinity provides structural stability. The combination achieves overall high degree of crystallinity (improving stability) while the presence of component (a) maintains sufficient processability and drawability
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 resulting polymer composition exhibits significantly improved drawability and high tensile strength, enabling the production of molded articles with enhanced mechanical properties suitable for solid phase drawing molding.
Implementation Method 1
carrying out a polymerization in two or more stages: in an initial first stage, an ethylene polymer (a) with an intrinsic viscosity of not less than 2 dL/g and not more than 20 dL/g is produced; in a subsequent second stage, an ethylene polymer (b) with an intrinsic viscosity of more than 35 dL/g and not more than 50 dL/g is produced
Implementation Method 2
using a solid titanium catalyst and organometallic compounds
Implementation Method 3
An ethylene polymer composition with a specific molecular weight range (30 dL/g to 50 dL/g) is achieved through a two-stage polymerization process, combining polymers with intrinsic viscosities of 2-20 dL/g and 35-50 dL/g
Implementation Method 4
enabling the production of molded articles with enhanced mechanical properties suitable for solid phase drawing molding
Data Source
AI summary
Provided is an ethylene polymer composition which can be obtained with a solid phase method such as solid phase drawing molding, is suitable for producing a molded article having high strength, and has the following properties. This ethylene polymer composition comprises an ethylene polymer (a) with an intrinsic viscosity [η] of not less than 2 dL/g and not more than 20 dL/g and an ethylene polymer (b) with an intrinsic viscosity [η] of more than 35 dL/g and not more than 50 dL/g, with the mass ratio (a) / (b) being from 0/100 to 50/50 and the [η] for the entire composition being more than 30 dL/g and not more than 50 dL/g. The method for producing the ethylene polymer composition includes, for example, the polymerization of an ethylene-containing olefin under specific conditions using a catalyst for olefin polymerization which comprises a solid titanium catalyst component comprising magnesium, a halogen and titanium.