From raw materials to finished products, an indispensable tool for the quality management of the entire coating process-laser particle size analyzer

The coating industry is a typical "surface engineering".
We see that the bright and beautiful appearance of automobiles, the white walls of offices, black and white appliances, etc.
are all kinds of coatings at play
.
"Paint Technology" defines paint like this: paint is a material that can be coated on the surface of an object with different construction techniques to form a solid film that is firmly adhered, has a certain strength, and is continuous
.
The film formed in this way is generally called coating film, also called paint film or coating coating online coatingol.
com
.
Coatings generally consist of four parts: film-forming substances (resin, emulsion), pigments, additives, and solvents
.
In the entire production process of coatings, it is first necessary to pay attention to the particle size distribution of the raw material pigments in order to control the cost and ensure the stability of the process
.
If rough raw materials are purchased, higher grinding energy consumption will be required in subsequent processing, and at the same time it will also bring about adjustments in the production process
.
Secondly, during the grinding process, the particle size reduction process should also be monitored to prevent over-grinding or under-grinding
.
Finally, when the finished product is tested at the factory, a particle size analyzer is still needed to determine the rationality of the distribution of solid particles to ensure the quality and stability of the coating
.
Therefore, from raw materials to finished products, the laser particle size analyzer is an indispensable tool for the quality management of the entire coating process
.

Three particle size testing links in a typical coating production process

Since the laser particle size analyzer is so important to the coatings industry, let's take the powder coating as an example to see what effect the particle size has on the quality of the coating?

01 Affect the powdering rate of powder coatings

The adhesion force during powder coating spraying mainly comes from the Coulomb force of electrostatic charge
.
The chargeability of the powder is proportional to the square of the particle size
.
The increase in the amount of charge increases the powdering rate, and if the powder is too fine, the chargeability decreases, and the powdering rate decreases
.
Generally speaking, the larger the particle size, the better the chargeability, but the growth rate of the particle's gravity with the increase of the particle size is greater than the growth rate of the Coulomb force
.
That is to say, when the particles are large enough, the gravity will be much larger than the Coulomb force, which will result in poor powder loading rate and coating effect
.
Therefore, the particle size of the powder coating particles in an ideal state should be controlled as far as possible between 10μm-70μm
.

02 Affect the appearance and leveling of powder coatings

In use, the powder coating is adsorbed on the workpiece and heated to form a high-viscosity fluid state, and then gradually level and solidify
.
The smaller the particle size of the coating, the better the leveling of the coating film, and the smoother and smoother the appearance
.
The particle size of the coating is directly proportional to the leveling time
.
Uneven particle size distribution of powder coatings or too coarse particles will seriously affect the appearance and leveling
.

The leveling effect of powder coating with uniform particle size distribution is obvious

03 Affect the thickness of the coating

The average particle size of traditional powder coatings is generally controlled at 30-50 microns, and the coating thickness is generally between 60-100 microns
.
Different types of workpieces require different coating thicknesses
.
At the same time, the thickness of the coating also greatly affects the area that can be coated by a unit weight of powder coating
.
Therefore, the particle size distribution of powder coatings can be said to be an important parameter that directly affects coating performance and economy
.

04 Affect the storage performance and stability of the coating

The finer the particles, the easier it is to absorb moisture, agglomerate, and decrease the stability.
It is easy to cause clogging of the spray gun and poor powder ejection during use
.
Therefore, the powder coating has a critical particle size, larger than this particle size, the powder is not easy to agglomerate, otherwise it is easy to agglomerate
.
The particle size of the coating product should not be lower than the critical particle size, otherwise the storage and use stability of the product will become very poor
.

05 Affect the recovery rate of powder coatings

Powder coatings have recycling problems in the production and use process.
Generally, the recovery rate of ultra-fine powders with a particle size of less than 10μm is low.
When the particle size is greater than 10μm, the recovery rate of powder coatings increases rapidly, and the recovery rate of powder increases with The increase in particle size increases
.

In the actual production process, the national/industry standards for powder coatings are mainly based on laser particle size analyzers, and dry methods are recommended
.
The current detection standards for active pigments are generally the determination of pigment sieve residue, sieving method, scraper fineness method, etc.
However, some companies/units have widely used laser particle size for R&D and quality control, which is simple to operate, fast, accurate, and reproducible.
Instrument
.

LS 13320 series laser particle size analyzer

The LS13320 series of laser particle size analyzers produced by Beckman Coulter in the United States not only meets and surpasses the requirements for laser particle size analyzers in relevant coating standards, but has been widely recognized and applied in the coating field
.

Compared with ordinary laser particle size analyzers, LS13320 can easily achieve "high resolution", "high accuracy" and "high sensitivity" by virtue of its characteristic XD array detector + PIDS patented technology
.
Help customers discover the subtle differences in the particle size distribution of various powder particles, and ensure the authenticity of the sub-micron particle detection results
.

In addition, the patented technology of LS13320 tornado dry method does not require an air compressor, and automatically adjusts the sampling speed, so that the powder coating that meets the Gaussian distribution can get an excellent dispersion effect, ensuring that the morphology of the original particles will not be damaged, and the authenticity of the particle size distribution test
.

The above content is mainly based on powder coatings as an example, explaining the application of laser particle size analyzer in the coating field
.
If your product is water-based or oil-based paint, don't worry, Beckman Coulter can still provide you with an excellent particle size testing solution, and the purchase cost of the instrument is lower than the dry equipment described above
.
This is the wet wet laser particle size analyzer with ULM configuration through the liquid sample stage
.

Beckman Coulter Wet Laser Particle Sizer Universal Liquid Sample Station

The particle size and particle size distribution of water-dispersed resins have become one of the main indicators that should be tested when synthesizing this type of resin.

Test practice of Beckman Coulter particle size analyzer for water-based coatings

In summary, the quality inspection and technology veterans of the coating industry, please don't hesitate whether the laboratory needs a laser particle size analyzer! What kind of particle size analyzer is required? You can contact our Beckman Coulter application engineers to help you choose