Understand the significance of microorganisms in coatings

The repeated outbreaks of the new crown epidemic have greatly educated human beings that they must further improve their understanding
of microorganisms.
Microbes are everywhere, they are found in every part of the human organism, on every surface, on everything used in daily life, and in the air
.

There are also traces of them in our food products coatingol.
com
more or less paint online.
In nature, they are found in soil and water bodies
.
They exist in a variety of ecosystems, trillions in number, with thousands of different types
.
Its activity depends on the environment related to chemical and physical factors such as organic matter, oxygen pressure, tidality, acidity, alkalinity, temperature, etc
.

In soil, microbes are the source
of a range of simple and complex tasks.
The completion of such tasks creates a normal balance
of basic elements and organic matter.
This balance, in turn, brings nutrients to the soil
.
In terrestrial environments, they are responsible for disposing of dead organisms, where carcasses and dead plants decay, ferment and metamorphosis to fertilize
the soil.
This ability to destroy complex organisms also becomes a threat
to humanity.

Water is the source of
life.
Humans and microorganisms cannot reproduce without water
.
This basic fact
is noticed from the growth of clay on the surface of the water in stagnant ponds, from fruits, bread, meat and other foods that can mold even in the refrigerator at temperatures of 5°C or even lower, from champagne or wine to acidity, etc.

Microbiological problems encountered in the coatings industry must also be of particular concern
.

Any watery organic matter is a potential problem
of microbial contamination and destruction.
The life course of microorganisms takes place in an aqueous medium, where water is the cornerstone of
their existence.
As long as water is present, microorganisms can survive
even if there are other negative factors in the environment.
Without water, microorganisms
cannot exist.

In order to understand the significance of microorganisms in coatings, it should be assumed that microorganisms are microscopic chemical factors
that can carry out many different processes.
They work day and night, causing loss of viscosity, spoilage, gassing, demulsification and other undesirable physical and chemical changes
.

The amount of moisture present in a commodity will determine whether it will be infected by bacteria or mold, and the water content of 15%~35% will help mold growth, and reaching more than 35% will be conducive to the reproduction
of bacteria.
It is often assumed that free water, i.
e.
unbound water, is a prerequisite
for bacterial reproduction.
When it comes to emulsions, a very low percentage of water is sufficient to allow and encourage the reproduction of microorganisms, because it is the tide at a certain point, not the total water content of the entire system, that determines the conditions
that can cause reproduction.

The factors that affect the growth of microorganisms are the presence or absence of nutrients, temperature, oxygen and pH
.
Individually or in combination, these factors determine which bacteria or mold will survive in a particular environment and at
what rate.

Even the thinnest food sources can be exploited
by microorganisms.
In practical terms, that is, if you want to protect a system from defacement, you must protect its whole, not just the imaginary vulnerable parts
.
For example, in the production process of water-based paint, cellulose thickener is a source of nutrition, and it is necessary to add a biocide such as 0.
1% or more when its water-soluble slurry is used, and when further using the slurry to mix the paint, it is necessary to add CIT+MIT biocide such as 0.
3% or more
to the paint mixing material.

Temperature determines the rate
at which microorganisms grow.
In the freezing range, most bacteria and molds stop growing and actually enter a dormant period, but many continue to actively reproduce
.
Most bacteria are killed when exposed to high temperatures for a long time
.
However, there is a class of bacteria called affectionate bacteria that can survive for a considerable time at 70 ° C
.
The temperature of 25~37 °C is most suitable for most bacteria, and 22~30 °C is beneficial to most molds; It can be seen that in the summer when the outdoor high temperature is above 35°C, it is easy to multiply bacteria and mold in the water-based paint cans stored indoors, resulting in yellowing, blackening, mold and odor
of the lacquer.

Oxygen has a limited effect
on microbial growth.
Most bacteria and molds survive aerobically and are called aerobic bacteria
.
During the sleep phase, the demand for oxygen is close to zero
.
Microorganisms in active growth demand more aerobic, which is a biological law
.
Therefore, for canned water-based coatings, if the can be filled with nitrogen and then capped after canning, its shelf life can be extended longer
.

Another type of bacteria is called anaerobic bacteria, which live anaerobically and can live deep in liquids without dissolved oxygen, or in
sealed containers where oxygen has been depleted.
There is also a class of bacteria that is somewhere between
aerobic and anaerobic.
These so-called microaerobic bacteria require very small amounts of oxygen
.
Many of them continue their lives even in the absence of oxygen
.

The pH range of the coating system also plays a
role in the growth of bacteria and mold.
Most of the most common microorganisms are most vigorous
at pH 7.
But they can tolerate a much wider
pH range.
For example, there is a main mold that discolors exterior wall paint, which can grow
in the range of pH3~10.
The same is true of bacteria, which, of course, may not grow optimally at the two extremes of the pH range, but they do survive and multiply
in small quantities.
The pH value of latex paint is generally controlled at 8-10, so it is prone to the risk of microbial growth; The pH value of silicate inorganic coatings is generally as high as 11-12, the growth of microorganisms is greatly inhibited, and the risk of odor and mildew is relatively low
.