Conductive PBT-PET Composition for Electrostatic Paint Adhesion
Solution Overview
Problem
Existing compositions comprising polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) are not suitable for electrostatic painting due to insufficient paint adhesion, despite being made electrically conductive with additives like carbon black or carbon nanotubes.
Innovation Solution
A method for preparing a composition with specific ratios of PBT and PET, combined with a filler like talc and an electrically conductive additive, achieving a melt viscosity of 160-400 Pa·s and a volume resistivity of ≤10^5 Ω·cm, allowing for effective electrostatic painting with good adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrically conductive additives such as carbon black or carbon nanotubes are added to PBT and PET compositions, then electrical conductivity is improved, but paint adhesion deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of conductive additives (0.1-5.0 wt% carbon black or 0.01-1.0 wt% carbon nanotubes) and adjusting processing parameters (melt temperature 200-300°C, shear rate 100-500 s⁻¹) to achieve optimal balance between conductivity and paint adhesion. This resolves the contradiction by finding the precise parameter window where both requirements are satisfied simultaneously.
Solution Approach 2:
The patent uses composite materials by combining PBT and PET in specific ratios (PBT 30-70 wt%, PET 30-70 wt%) with conductive additives and optional fillers to create a multi-component system where the polyester matrix provides paint adhesion while the conductive additives provide electrical conductivity, resolving the contradiction through material composition design.
2Reliability
If the composition is made electrically conductive with additives, then electrostatic painting capability is improved, but mechanical properties deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the concentration of conductive additives within specific ranges (0.1-5.0 wt% for carbon black, 0.01-1.0 wt% for carbon nanotubes) and optimizing processing conditions (melt temperature 200-300°C, shear rate 100-500 s⁻¹) to maintain mechanical integrity while achieving sufficient electrostatic painting capability.
Solution Approach 2:
The patent uses composite materials design where PBT and PET form a strong matrix structure that maintains mechanical properties, while dispersed conductive additives provide electrostatic painting capability without compromising the overall mechanical strength of the composition.
3Reliability
If conductive additives are added to achieve volume resistivity ≤10^5 Ω·cm, then electrostatic painting suitability is improved, but melt viscosity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration of conductive additives and controlling processing conditions (melt temperature 200-300°C, shear rate 100-500 s⁻¹) to achieve the required volume resistivity (≤10^5 Ω·cm) while maintaining acceptable melt viscosity for manufacturing processes.
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 method results in a composition that can be electrostatically painted with improved adhesion, maintaining sufficient mechanical properties and paintability while optimizing the use of conductive additives.
Implementation Method 1
Plastics can be made electrically conductive by adding an electrically conductive additive such as metals, electrically conductive carbon black, carbon fibers and carbon nanotubes
Implementation Method 2
Electrostatic painting is a process in which paint is projected towards a electrically conductive piece by for example spraying method
Data Source
AI summary
This invention relates to a method for preparing a composition having a melt viscosity of between 160 Pas and 400 Pas, as determined according to ISO-11443-2014 at 270 °C and a shear rate of 265 1/s, and a volume resistivity of at most 105 Ohm. cm, measured according to ASTM D257 on an injection molded test sample of 3 mm thickness and a diameter of 50 mm and coated with a gold layer on an upper and lower surface and, as well as the composition itself and painted parts comprising the composition.