Multimodal HDPE Masterbatch for Pigment Dispersion and Sag Resistance

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Solution Overview

Problem

The challenge in pipe manufacturing lies in achieving good dispersion of pigments in polyethylene compositions, particularly with high pigment loadings, which increases viscosity, and the issue of sagging during pipe conversion due to differences in molecular weights between carrier polymers and base resins, affecting processability and mechanical properties.

Innovation Solution

A multimodal high-density polyethylene (HDPE) carrier polymer with a specific molecular weight distribution is used in the masterbatch, ensuring better dispersion and reduced sagging by maintaining low shear viscosity while maintaining high shear viscosity, thus improving filler wetting and mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high pigment loading is used in the masterbatch, then color intensity and UV stabilization are improved, but viscosity increases substantially making dispersion difficult

Engineering Contradiction:

Improvepigment loadingVSAvoiddispersion difficulty

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent changes the molecular weight distribution parameters of the carrier polymer from unimodal to multimodal, creating a broader MWD that enables high pigment loading (40-50 wt%) while maintaining manageable viscosity for dispersion. The specific parameter change is the molecular weight distribution shape, which allows the system to accommodate high pigment concentrations without excessive viscosity increase.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If unimodal carrier polymer with high MFR is used, then viscosity is reduced improving dispersion, but sagging increases during pipe conversion

Engineering Contradiction:

Improveviscosity controlVSAvoidsagging

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite molecular weight distribution by combining multiple polymer components with different molecular weights (multimodal MWD). This composite structure provides dual functionality: the lower molecular weight portion reduces viscosity for good dispersion, while the higher molecular weight portion provides sag resistance during pipe conversion, eliminating the need to choose between the two opposing requirements.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If carrier polymer with lower molecular weight is used, then dispersion is improved, but sagging resistance decreases

Engineering Contradiction:

Improvedispersion qualityVSAvoidsagging resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent segments the molecular weight distribution into multiple distinct portions (multimodal), where each segment performs a specific function. The lower molecular weight segment (first mode) provides good dispersion and filler wetting, while the higher molecular weight segment (second mode) provides sag resistance. This segmentation allows both functions to coexist without compromising either property.

Inventive Principle:

Principle #1Segmentation

4Object-affected harmful factors

If high melt viscosity is used to prevent sagging, then sagging is reduced, but processability and production rate decrease

Engineering Contradiction:

Improvesagging preventionVSAvoidproduction rate

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent creates a dynamic viscosity profile through multimodal MWD that adapts to different processing conditions. At low shear rates (during pipe formation), the higher molecular weight portion dominates providing high viscosity for sag prevention. At high shear rates (during extrusion and mixing), the viscosity decreases appropriately, maintaining good processability and production rate. This dynamic behavior eliminates the trade-off between sag prevention and productivity.

Inventive Principle:

Principle #15Dynamics

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 use of multimodal HDPE carrier polymers in masterbatches achieves well-dispersed pigments and improved mechanical properties, reducing sagging and maintaining processability, making the polymer composition suitable for various applications including pressure pipes.

Implementation Method 1

The carrier polymer is a multimodal polyethylene polymer... ensuring better dispersion and reduced sagging by maintaining low shear viscosity while maintaining high shear viscosity

Methodology Applied

Scientific EffectViscosity control through molecular weight distribution:

Implementation Method 2

reducing sagging by maintaining low shear viscosity while maintaining high shear viscosity

Methodology Applied

Scientific EffectViscosity control through molecular weight distribution:

Implementation Method 3

improving filler wetting and mechanical properties

Methodology Applied

Scientific EffectWetting: Wetting

Data Source

PatentEP3090011B2Polymer composition comprising carbon black and a carrier polymer for the carbon black

Publication Date: 2022.06.08 ABU DHABI POLYMERS CO LTD BOROUGE

Figure 1

AI summary

A masterbatch (MB) comprising, preferably consisting of, (I) 20-50 wt% pigment based on the total amount of the masterbatch (100 wt%); (II) at least 40 wt% of at least one carrier polymer which is a multimodal high density polyethylene (HDPE) polymer having an MFR2 of 1 to 20 g/ min, a density of 940 to 965 kg/m 3 (pref 950 to 960) and a Mw/Mn of 5.5 to 20; and (IV) optionally further additives.