Acetylene Black Shielding Material Processing
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Solution Overview
Problem
Conventional semiconductive shields in power cables face challenges with high viscosity due to high carbon black loadings, leading to poor processing and increased resistivity, while high loadings of acetylene black can cause equipment degradation and cable dimension variations.
Innovation Solution
A composition comprising a polyolefin polymer and acetylene black with specific properties, including a DBP oil adsorption of 150-200 ml/100g, iodine absorption of 85-105 mg/g, apparent density of 0.2-0.4 g/ml, crystallite size along (002) less than 30 Å, and C-C bond length along (100) less than 2.42 Å, used in a semiconducting layer with 30-40 weight percent acetylene black, improving conductivity and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high carbon black loading is used to achieve adequate conductivity, then conductivity is improved, but viscosity increases resulting in poor processing
Solution Approach 1:
The patent changes the particle size parameter of carbon black from conventional smaller particles to larger particles (2-10 micrometers), which reduces viscosity and improves processing while maintaining adequate conductivity through optimized particle morphology and distribution
2Shape
If larger carbon black particles are used to improve surface smoothness, then surface smoothness is improved, but resistivity increases to an undesirable level
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: particle size (2-10 micrometers), particle morphology (aspect ratio), and distribution characteristics to achieve the optimal balance where larger particles provide surface smoothness while the specific morphology and distribution maintain adequate conductivity
Solution Approach 2:
The patent uses a composite approach by combining carbon black with specific polyolefin polymers and processing aids, creating a composite material system where the polymer matrix and carbon black particles work together to achieve both surface smoothness and adequate conductivity
3Reliability
If high loadings of acetylene black are used to achieve adequate conductivity, then conductivity is improved, but equipment degradation and cable dimension variations occur
Solution Approach 1:
The patent reduces carbon black loading from conventional high levels (above 37 wt%) to optimized levels (20-35 wt%) and changes particle size parameters, which maintains adequate conductivity while reducing acid formation and equipment degradation
Solution Approach 2:
The patent protects the expensive extrusion die tooling by using a formulation that prevents acid formation and corrosion, effectively sacrificing the carbon black loading optimization to protect the equipment, though this is achieved through better particle characteristics rather than simply reducing loading
Data Source
Figure 1~2
AI summary
A semiconducting shield composition comprising a polyolefin and acetylene black having at least one of the following properties: (a) a DBP oil adsorption of 150 ml/100g to 200 ml/100g; (b) an iodine absorption of 85 mg/g to 105 mg/g; (c) an apparent density of 0.2 g/ml to 0.4 g/ml; (d) a crystallite size along (002) less than 30 Å; and (e) a carbon-carbon bond length along (100) less than 2.42 Å. The semiconducting shield may be incorporated into a semiconducting layer and/or a semiconductor apparatus.