Polyamide Powder Coating with Polypropylene Glycol to Prevent Fish Eyes
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Solution Overview
Problem
Polyamide-based powder coatings often suffer from defects such as pitting, fish eyes, and pigment flight during the powder coating process, leading to unsightly and potentially corrosive surfaces, especially when using metallic or pearlescent pigments.
Innovation Solution
A polyamide powder composition containing 50-99.99% polyamide powder, 0.01-0.5% polypropylene glycol, and 0.1-10% pigments, where polypropylene glycol is added by dry mixing to prevent pigment flight and surface defects, allowing for a smooth, defect-free coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyamide powder is used for coating, then abrasion resistance and corrosion resistance are improved, but surface defects such as fish eyes and pitting occur
Solution Approach 1:
The invention changes the chemical composition parameters of the polyamide powder by incorporating specific additives (polypropylene glycol and silicon dioxide) to modify the melting and flow behavior of the polymer, thereby eliminating surface defects while preserving corrosion resistance
Solution Approach 2:
The invention creates a composite powder material combining polyamide with polypropylene glycol and silicon dioxide, where each component contributes specific properties: polyamide provides corrosion resistance, polypropylene glycol improves flow and prevents fish eyes, and silicon dioxide prevents pitting and enhances surface quality
2Illumination intensity
If metallic or pearlescent pigments are added to achieve aesthetic appearance, then coating aesthetics are improved, but pigment flight and fish eyes increase
Solution Approach 1:
The invention introduces polypropylene glycol as an intermediary substance that mediates between the pigment particles and the polyamide matrix, improving pigment distribution and preventing fish eyes caused by poor compatibility between pigments and polyamide
Solution Approach 2:
The invention modifies the rheological parameters of the melting powder through additive incorporation, enabling better pigment suspension and distribution during the coating process, thereby preventing pigment flight and improving coating uniformity
3Ease of manufacture
If powder coating process is used, then ease of implementation is improved, but pitting and fish eyes occur on coating surface
Solution Approach 1:
The invention modifies the thermal and flow parameters of the powder coating material by incorporating specific additives, enabling the powder to melt and flow more uniformly during the coating process, thereby preventing surface defects while maintaining process simplicity
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 composition effectively prevents the formation of fish eyes and craters, ensuring a smooth, high-quality coating with improved pigment distribution and retention, maintaining the abrasion and corrosion resistance properties of polyamide coatings.
Implementation Method 1
said composition being obtained by dry mixing of polyamide and polypropylene glycol
Implementation Method 2
the powder thus charged is projected onto the object to be covered connected to zero potential. According to another form of electrostatic powdering, the object connected to zero potential is dipped in a fluidized bed of charged powder. Inside the fluidized bed is powder with which we want to cover the object. This powder is in the form of small solid particles, that is to say of size between 0.01 and 1 mm, of any shape, which are in a state of fluidization inside the bed in the presence of air. or any other gas. In the fluidized bed there are electrodes to charge the powder by corona effect or a device to charge it by triboelectric effect. The powder-coated object is then placed at a sufficient temperature, for example in an oven, to ensure coating by fusion of the powder causing film formation.
Implementation Method 3
charging the powder with static electricity and putting it in contact with the object to be covered connected to zero potential. For example, the powder is injected into an electrostatic gun which will charge the said powder by Corona effect (also called corona effect), by triboelectrification or by a combination of the two.
Implementation Method 4
the powder is injected into an electrostatic gun which will charge the said powder by Corona effect (also called corona effect)
Implementation Method 5
by triboelectrification or by a combination of the two
Implementation Method 6
A second type of process consists of preheating the object to be covered to a temperature higher than the melting temperature of the powder. Once hot, the object is immediately immersed in a fluidized bed of powder, the powder melts on contact with the hot object and forms a film.
Data Source
AI summary
The present invention relates to a coating composition in the form of a loose powder including the following by weight: 50% to 99.99% of polyamide powder, and 0.01% to 0.5% of polypropylene glycol, out of the total weight of the composition. The present invention relates in particular to a coating composition in the form of a powder including the following by weight: 50% to 99.9% of polyamide powder, 0.01% to 10% of at least one pigment and 0.01% to 0.5% of polypropylene glycol, out of the total weight of the composition. The present invention relates in particular to the use of said composition in methods for coating objects, in particular metal, by means of stuccoing.