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New environmentally friendly wetting agents are used in architectural coatings
building coating formulators must constantly adapt to higher performance standards and stricter environmental standards, as well as cost pressures. Recently, global paint manufacturers are promoting the non-use of
APE
) in their building coating formulations. In addition, VOCs in today'
are
being gradually reduced or eliminated. All of these measures help make formulations more environmentally friendly and environmentally friendly, but at what cost do you need to achieve these properties? Concerns about environmental and permanent toxic materials have prompted consumers to seek new additives that should have the same or higher properties at the same price as traditional additives currently in use. A new environmentally friendly building coating wetting agent has been developed that can replace pure or modified alkyl phenol ethyl ester (
APEs
). This new
APE
-free surfactant provides excellent performance: it can effectively wet titanium dioxide pigments during grinding, improve the freezing and melting stability and viscosity stability of the preparation coating, can control the formation of foam well, has good scrub resistance, has improved fluidity and leveling, and does not add additional
VOCs
to the coating formulation.
background
lotions or latexes, pigments and additives (see figure
1
). Each material plays an important role in the overall performance of the final coating, so raw material selection is critical. Incorrect selection of any material can have a significant impact on the performance of the coating. For example, choosing the wrong paint base can lead to poor durability, too long drying time, or poor attachment to the substrate. Similarly, choosing an inappropriate wetting agent or surfactant can cause the pigment to disperse badly, leaving the paint film with no luster or an unpast look. For architectural coatings, surfactants are usually used to reduce the free energy of the surface or interface of the water phase, so that the pigment can be well moisturized and effectively ground, the substrate wet consistent and form a defect-free coating. The good wetting properties in these applications have been confirmed by the fact that the low dynamic surface stress values that occur during production and construction, and the quick migration of surfactants into the newly generated interface. Low dynamic surface stress enables all surfaces to be well moisturized and pigments to be effectively ground, which in turn leads to increased coverage and adhesion, reduced grinding times, and promoted color formation.
surfactant
is a chemical that can be adsorbed to the surface or system interface. Surfactants have characteristic molecular structures that contain water-like hydrophobic parts and oil-like pro-fat (hydrophobic) parts. Due to its sex structure, at low concentrations, surfactants gather at the air
/
interface, reducing surface and interface stress.
the traditional surfactant is connected to the tail of a hydrocarbon (hydrophobic part) on the head of the polar or ion type (hydrophobic part). In contrast, the double surfactant is in the same molecule with two hydrophobic ends and two hydrophobic ends. Half of a double surfactant consisting of a hydrophobic end and a hydrophobic end is connected to the isolation and then to the same part of the molecule to form a double surfactant structure (Figure
2
). Due to its unique molecular structure, dual surfactants usually have more active surfaces in order of magnitude than the corresponding traditional surfactants. Bis surfactants based on ethylene binary alcohols (
2,4,7,9-
-tetetymyl
-5-
-glycol
-4-7-
glycol and its ethylene
)
are widely used in building coatings to improve wetting and foam control
1
.
solvent-based coatings to water-based systems, additive manufacturers face challenges. Solvent-based systems typically have surface stresses in the range of
25
to
35 mN/m
, mostly due to solvents used in these systems. On the other hand, the surface stress value of a water-based coating is usually
50 mN/m
or higher, mainly due to the high surface stress value of
72 mN/m
. When applying a water-based system to a substrate with a surface of
35
to
45 mN/m
, the surface pressure of the coating must be reduced by
2
. As
3
, spontaneous wetting of the surface only occurs when the surface pressure of the liquid is lower than the surface energy of the substrate. To do this, surfactants or moisturizers are usually used in water-based coatings.
the process of
pigment dispersion is usually defined as the addition of three separate processes. The first process is to moisten the dry pigment to replace air or other impurities on the pigment surface. Once the outside of the pigment particles is fully moisturized, it can be ground so that large pigment aggregates and condensates become particles of their original size. The final step is to stabilize the dispersion and improve the stability of color and viscosity, as well as impact resistance and relaxation compatibility.
for water-based coatings, the dispersion process faces some challenges. For example, the high surface tension of water and the high interface tension between the continuous water phase and the pigment must be reduced to a low enough level to wet the pigment particles, as shown in figure
4
. To reduce surface and interface stress, use surfactants that moisten pigments. These additives, which are adsorbed to the pigment surface, reduce the interface stress and, in order to form dispersed and stable molecules, the pigment needs to further absorb the surfactant
3
. Grinding efficiency increases when surface and interface pressure is reduced. This results in shorter grinding times, lower energy required to form particles of the original size, lower grinding temperatures, and lower viscosity of the grinding slurry, which increases pigment addition.
traditional wetting agents are alkyl phenol ethyl esters (
). APEs
) with excellent ability to wet the outer surface of pigments. The trend to replace
materials
coatings is increasing due to increased understanding of the effects of the APEs on their property destruction of the endocrine system and adverse health effects. Due to its hydropability,
APEs
stable foam and cause water sensitivity to the final paint film. The use of these surfactants can also lead to the use of strong defrosting agents to control the formation of foam, which in turn can lead to defects in the final paint film. Choosing the right pigment wetting agent not only provides the most effective grinding and color formation, but also helps prevent foam generation during production and construction.
once the pigment aggregate is broken into particles of the original size, the particles must be stabilized to prevent regagging or flocculation. As
5
, this stability can usually be achieved by bit resistance or electrostation stabilization. Static stability is achieved through a double layer, which is formed by molecules adsorbed on the surface of particles. Bit resistance stability is achieved through the interaction of hydro-water chain segments of molecules adsorbed to the surface of particles in the
phase
. These stable hydrophobic segments usually come from surfactants containing alkyl phenol ethyl esters, mesothropolic sulfonates, or polymer molecules such as amine-in-the-mediocyclic acid copolymers. According to the formula, an additive can be used in both wetting and stabilizing processes. Pigment type, construction parameters and cost are all factors to consider when selecting a dispersant combination.
the development of new surfactants
additives used in architectural coatings are not only used to wet pigments and substrates, but also to help control foams. There are also improvements in durability, adhesion resistance, color formation, washability or scrub resistance, while also helping to reduce
VOCs
. A new
APE
-free surfactant has been developed to improve these properties in the most cost-effective manner, while keeping the
VOC
content of the final formulation to a minimum.
application
three types of coating formulations have been prepared to evaluate the performance of this new
APE
-free wetting agent. These recipes are below
1-3
. Based on this new surfactant (code-named
E2010
), two commercially available surfactants containing
APE
are named
E
low-foam surfactants (
LFAPE
) and hydrophobic modified
APE
(
HMAPE
). Use all of these additives according to the recommended usage in the starting formula. The physical properties of these surfactants to be tested are
4
.
these formulations are prepared in accordance with the procedures prescribed by the manufacturer and then applied with
3
mil scrapers. The viscosity is measured with a digital stomo viscosity meter after
24
hours of preparation of these coatings and two weeks after
50
degrees C is placed, as viscosity indicates the stability of the coating. A model for testing anti-adhesion is to apply the coating to the
Leneta
recorder with a
3
mil scraper, let the coating dry at room temperature for
24
hours, then place it face-to-face for
1
hours before pulling it apart.
use
BYK Gardner Spectro-Glide 45/0
gloss gauge measures gloss and pair ratios. For a cleansing test, color the paint with the recommended coloring paste and apply it to a
Leneta1B
recorder with a
3
mil scraper for
1
minutes. Rub the paint part for
30
seconds, then dry the recording paper for 24 hours
temperature
humidity. Once the coating is cured, the chroma between the areas that have been rubbed on the recording paper and the areas that have not been rubbed can be measured. The E
value
is below
1
can get a "pass" rating.
used
Leneta
the flow hook value with an antiflow gauge and test the leveling value with
Leneta
level test knife
ASTM D4062
.
's
Red Devil
samples on a paint mixer for
15
minutes for foam testing while recording the density of the coating. To calculate the percentage change in foam density, the difference between the density of the unstranded sample and the density of the stirred sample is measured.
model is
The D10
scrub resistance with a washing and abrasive tester.
, in order to determine the stability of freezing and thawing,
300g
paint samples were called into
8
oz. lined canisters. Place the jar in a
at
degrees C and freeze for
15
hours, then melt at room temperature for
4
hours. Then place the jar in
bath
25 degrees C for
2
hours. Finally, stir the paint and test the stomo viscosity. Repeat this procedure
5
until the viscosity can no longer be tested. The last cycle in which viscosity can be tested is the reported value.
results and discussions
some notable features
4
illustrate the ease of use of newly developed
APE
-free surfactants. The dumping temperature point is
0
C, and in cold environments, the E2010
much
much easier to handle.
the cloud
E2010 is also significantly higher than that of the other two tested surfactants. Finally, due to its composition,
E2010
meets the requirements of
40CFR
regulations, making it an ideal surfactant for building coating applications.
to ultra-
The evaluation of the
formulation of eggshell paint in VOC
shows excellent performance compared to two other surfactants containing
APE
, samples containing
E2010
. As an alternative to
LFAPE
or
HMAPE
surfactants, the resulting coatings show that the
E2010
has many advantages
(
Table 5
)
. These advantages include excellent gloss control, increased opacity and coloring strength, and improved color acceptability and viscosity stability of the after-coloring system.
E2010
also provide excellent scrub resistance and improve adhesion resistance. All formulations show excellent flow and leveling as well as considerable foam control.
Table 6
6
the internal use of surfactants to be tested