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Application In Coatings
Function Principle Analysis And Application Example For Wet Method Sericite Mica In Coating |
In
the coating, add some wet method ultra fine sericite mica powder, may
shield the ultraviolet ray illumination, enhances weather resistance of
the coating, retards the chalking and color changes. With the
two-dimensional sheet structure of high aspect ratio, sericite mica can
enhances comprehensive machine capability of coating layer, such as the
waterproof, the anti- chap, staining resistance, acid resistance,
alkali resistance, the resistance for high temperature, performance of
heat-resistance and the anti ¨Ccorrosion.
I. Application principle of wet method sericite mica in coating
1. Wet method sericite mica has unique shield ultraviolet ray characteristic
a. Crystal polarized light effect
US'S H.S.Katz and other specialist thought that, the extinction
performance of inorganic filler is decided by different orientation of
mineral crystal, decided by absorption or reflective power to the
ultraviolet ray. The mineral structure of sericite mica is the
clinohedral system, it has three crystallographic axes A, B, C (see
Figure 2), the angle between A axis and C axis is 93¡ã, B axis is
vertical to A axis and C axis. The sericite mica has three main
refractive rates: Ng=1.588-1.615, Nm=1.582-1.611, Np=1.562-1.572. Light
position: Ng is parallel to B axis, it has has 3¡ãangle Nm between the A
axis and Nm. Np is parallel to C axis,. Indicatrix chart (chart 1
center): (Stands erect) by the Ng-Np surface, Nm-Ng (horizontal plane)
Nm-Np (longitudinal section) three ellipses sections compose, the Ng-Np
ellipse section has two optical axes, is called the plane of optic axis
(Ng-Np),Take Np (the c axis) as the even parting line, the included
angle 2V=15-30¡ãoptic angle of muscovite is 30-50¡ã.
Extinction degree of inorganic mineral is related at optic angle. The
bigger optic angle, the less the grey scale, the interference color is
higher. The smaller optic axis angle, the bigger the grey scale, the
extinction function is better. Therefore , to shielding ultraviolet
ray, the microwave function of the sericite mica mineral is better than
muscovite, more superior than other inorganic fillers.
Moreover, the effect of shields light is related with the order degree
of mineral arrangement, granulated, the fibrous mineral in spreads in
the film the arrangement disorder, the orientation at will. But the
laminated sericite mica have the high directing property in the film of
coating, is the parallel arrangement generally, overlaps up and down.
As the plane of optic axis (Ng-Np) of next two thin slices is
vertically mutually, the entire extinction will result. As slanting
junction, it will cause the interference color.
b. Interference effect of interlayer water molecular
In the sericite mica crystal the water of crystal is included, 2%
higher than muscovite mica. Index of refraction of crystal water is
1.33 but the index of refraction of aluminosilicate is 1.522-1.615, two
differences big, diffraction effect strong. In the structure of
sericite mica, the level space of intermediate deck is approximately 10
?, close with the wave length of ultraviolet ray and the microwave.
When the natural light passed through the sericite mica crystal,
because of the crystal polarized light vibration, will decomposes Ng,
the Np two bunches of polarized lights with different light speed,
again puts on the strata time to decompose again, causes Ng ' Np ' to
superpose in a plane of polarization, the polarized light energy
weakens gradually to the zero hour, then shields completely, appears
the extinction.
c. Adsorption properties test of sericite mica for ultraviolet ray
The coating of high performance hoped that the raw material can provide
good performance of weather resistance. Generally thought: the weather
resistance of fillers depend on power of the ultraviolet ray absorbed
energy, the more strongly the power of absorb, the greater contribution
to weather resistance. Presently, absorption spectrum to ultraviolet
ray of titanium oxide, kaolin as well as our wet method sericite mica
is indicated in chart 2:.
Determination chart of light adsorption rate¡ªtitanium dioxide, sericite mica and other fillers
Note:
1. Instrument: Lambda 900 UV/VIS/NIR Spectrometer;
2. Wave length of ultraviolet ray in: 190-370nm;
Graphic display that, the rutile titanium oxide powder absorb
ultraviolet ray wave trough at 88%, the standard sharp wet method
sericite mica absorb ultraviolet ray wave trough at 85%, wet method
sericite mica at 48%, calcined kaolin at 59%, but other mineral fillers
have basically no absorption function for ultraviolet ray.
The longer light wave energy only can cause the vibration of molecular
and the heat of surface. But the ultraviolet ray have the destructive
effect to chemical bond and so on C-H, C-C, C-Cl as well as has the
same key in the organic matter, thus causes the organic matter, the
high-molecular compound degrades into the small member. The ultraviolet
ray illumination can cause destruction of the pigment molecular
structure in the coating, the decomposition, degrades for other matter,
causes the color of paint to produce discoloration or the color change.
To use wet method sericite mica powder will protected C-H key of high
polymer material, thus to get up to the function to resist from color
change and detention chalking
2£®Laminated ¨Csheet shielding function of wet method sericite mica
Some minerals have the function of water resistance and the film
intensity in the coating, which is related to the mineral physical
shape, decreases progressively generally according to the following
order: laminated shape > is fibrous shape> columnarly shape>
granular shape. The sericite mica crystal is always the two-dimensional
sheet structure, also regardless of how small superfineness. Moreover
the sericite mica has the active hydroxyl groups, easily union and
connect with molecular chain unifies in the emulsoid, the solvent,
lines up in the parallel and overlaps up to down in the coating film,
causes to form one kind of compact level network structure, thus
enhanced greatly the comprehensive machine capability and the
impermeability
Chart3£ºElectronic microscope picture of wet method sericite mica
Chart4£ºPenetration way of water molecular in film of different structure
 II. Function confirmation of wet method sericite mica in coating
Wet method sericite mica is obtaining widespread utilization by its
unique physics and chemistry nature and application function as
following coatings:
architectural exterior coatings, anticorrosive paints, powder coatings,
fire-resistant paints, insulation coatings, road marking paints,
traffic paints, marine paints, radiation protective paints and special
functional paints ,
We are listing some application examples of wet method sericite in coatings as follows:
1. Improve weathering resistance of film by using the function of shielding ultraviolet ray
1). By putting different proportion, different specification of
sericite mica in exterior emulsion paints, artificial aging resistance
tests were made. Test formulation as table 1, test result as table 2.
Table1. Test formulation of sericite mica in exterior emulsion paints
Material name |
Specification or origin |
Quality |
Material name |
Specification or origin |
Quality |
Free ion water |
Own preparation |
200 |
Talc |
1000mesh |
60 |
Disperser |
DP512 (Deqian) |
3 |
Laundry blue |
Industry |
Moderate dose |
Defoamer |
080 (Deqian ) |
2 |
HEC |
Industry |
5 |
Propanediol |
Import |
10 |
Emusion |
ES322A |
360 |
Titanium dioxide |
R-930 |
160 |
Thickenner |
WT-105A(Deqian) |
10 |
Heavy CaCO3 |
800mesh |
100 |
PH regulator |
DATE(Deqian) |
1 |
Sericite mica |
uncertain |
50 |
Propylene glycol ether |
import |
20 |
Table 2 Performance test contrast of blank and adding different sericite mica powder
|
No addition |
GA-2 |
GA-4 |
Dry sericite |
ÒÁÀûʯ¾îÔÆĸ |
Time
|
|
|
|
|
|
|
400H
|
Appearance |
No blistering, no breaking off, no crack
|
Color change |
2 |
1 |
1 |
1 |
2 |
Chalking |
1 |
0 |
0 |
1 |
1 |
|
600H
|
Color change |
|
No blistering, no breaking off, no crack |
Blistering Breaking off |
|
Chalking |
|
|
|
|
|
Color change |
|
|
|
|
|
This experiment was carried on according to GB/T 1865 stipulations,
result judegement according to GB/T 1766. May see from the above test
data: addd the sericite mica in the exterior emulsion coating, can
enhance greatly whethering resistance of paint film. Comparing wet
method sericite mica, dry method sericite mica and illite sericite mica
have less much contribution to whethering resistance of paint film.
2). Adding wet method sericite mica in pure polyester powder coating .
Test formulation as table 3, test result as table 4.
Table 3. Test formulation-- Adding wet method sericite mica in pure polyester powder coating .
Seris |
Material |
1 |
2 |
Note |
1 |
CC8030 |
600 |
600 |
UCB or DSM( P5201) |
2 |
PT710 |
45 |
45 |
Vantico or China product TGIC |
3 |
PV88 |
10 |
10 |
Estron or China product GLP588 |
4 |
BaSO4 |
140 |
100 |
Guizhou of China |
5 |
Sericite mica |
0 |
40 |
Chuzhou Grea GA-5 |
6 |
TiO2 |
200 |
200 |
Dupond R-902 |
7 |
Benzoin |
2 |
5 |
Made in China |
|
In total |
1000 |
1000 |
|
Table4. Performance test-- Adding wet method sericite mica in pure polyester powder coating
Series No |
1 |
2 |
Remark |
Thickness of film (¦Ìm) |
60~70 |
60~70 |
GB/T1764-1979 |
Luster |
85 |
78 |
GB9754-1988 |
Impact (cm) |
50 |
50 |
GB1732-1993 |
Flection (cm) |
2 |
2 |
GB6742-1986 |
Wet heat resistance (1000h) |
Pass |
Pass |
GB/T1740-1979 |
(mm) |
6 |
6 |
GB9753-1988 |
Boiling water resitance (2h) |
Loss luster slightly |
Pass |
GB/T5237.4-2000 |
water resitance (1000h) |
Blistering slightly |
Pass |
GB/T1733-1993 |
Pencil hardness |
H |
2H |
GB6739-1996 |
Weathering resistance (1000h) |
Grade 3 |
Grade 1 |
Test As per GB/T1865-1997 , judegement as per B/T1766-1995
|
Note£ºCure condition 200¡æ 10min
May see from the above data: In pure polyester powder coating, add
sericite mica powder, not only may improve the appearance of paint
film, enhances the pencil hardness and the water resistance, moreover
improve greatly weathering resitance of paint film.
The concrete test data see Figure 5: The
data may know from Figure 5: does not add the sericte mica in the
formulation, artificial accelerated ageing test of coating, fcoating
film would have sudden change at 800 ~ 900 hours times , the gloss
drops sharply, after but adding the sericite mica, could inhibit
effectively the sudden change, enable the coating film still to
maintain higher rate of gloss retention, and increase anti-aging
performance of coating film.
2. Improve water-bleeding resistance of paint film by using mult-sheet hinder function of sericite mica .
In epoxy zinc rich primer, add different specification and proporation
of sericite mica to do experiment of regular items.
Specific experiment method see table 5 and table 6, Allocated
proportion of paint is A : B =10 : 1, test result see table 7.
Table 5
Group A test formulation
Series |
Material Name |
Specification or origin |
Quality |
1 |
60%601 epoxy resin |
Yuehua of China |
12 |
2 |
Anti-sediment agent |
Zhejiang Fenghong of Chian |
1 |
3 |
Thixotropic agent |
Import |
0.4 |
4 |
Dimethyl benezen |
Import |
8 |
5 |
Butyl alcohol |
Industry |
2.6 |
6 |
Zinc powder |
Hunan Changsha of China |
75 |
7 |
Sericite mica |
Uncertain |
5 |
Table 6£ºGroup A test formulation
Series |
Material Name |
Specification or origin |
Quality |
1 |
650 ancamide |
Wujin Dongfeng Chemical of China |
26 |
2 |
Dimethyl benezen |
Import |
37 |
3 |
Butyl alcohol |
Industry |
37 |
Note £º Dimethyl benezen : epoxy hexanone = 3:1
Table 7£ºPerformance test by adding different specification and proporation of sericite mica in In epoxy zinc rich primer
Kinds |
Blank |
GA-1 |
GA-2 |
Dry method sericite mica |
Illite sericite |
Performance |
|
|
|
|
|
Appearance of film |
Smoothly |
Smoothly |
Smoothly |
Smoothly |
Smoothly |
Storing properties (1 week) |
Good |
Good |
Good |
Precipitated slightly |
Expand |
Adhension(grade) |
1 |
1 |
1 |
1 |
1 |
Impact (kg.cm) |
50 |
50 |
50 |
50 |
50 |
Flexibility (mm) |
1 |
1 |
1 |
1 |
1 |
Water resistance (h) |
336 ¡ï |
336 ¡ï |
336 ¡ï |
336 ¡ï |
336 ¡ï |
Salt water resistance (h) |
312 |
512 |
560 |
348 |
365 |
Fog resistance ( h ) |
144 |
600 |
584 |
150 |
315 |
Note£º¡°¡ï¡°£º Refers to the water resistance to examine after 336h, the
model has not been bad, but stops experimenting
May see from the above test result: mult-sheet hinder function of
sericite mica .may obviously enhance the salt water resistance and fog
resistance of paint film, at the same time the fuction of wet method
silk mica must be better dry method sericite mica and the illite
sericite mica powder.
3.
Using good flatting properties of sericite mica, it can replace partly
high-cost flatting agent, so reduce cost of production for flat paint
and semi-flat paint.
The
silk mica has the certain flatting function, makes good use of this
point to be possible to replace the flatting agent use, reduces the
coating formula cost, enhances the market competitive power. Concrete
application example as follows
Test formulation and property test table (formulation only for reference)
Series No |
Materials |
1 |
2 |
3 |
4 |
1 |
P5127 |
300 |
300 |
300 |
250 |
2 |
663U |
300 |
300 |
300 |
350 |
3 |
PV88 |
10 |
10 |
10 |
10 |
4 |
BaSO4 |
150 |
100 |
50 |
170 |
5 |
TiO2 |
200 |
200 |
200 |
200 |
6 |
Mica |
0 |
50 |
100 |
0 |
7 |
benzoin |
5 |
5 |
5 |
5 |
8 |
Hydrogenated castor oil |
5 |
5 |
5 |
5 |
9 |
Flatting agent |
0 |
0 |
0 |
10 |
|
In total |
1000 |
1000 |
1000 |
1000 |
Condition of cure |
180¡¡¡¡15 min
|
Film thickness (micro meter) |
60¡ª70 |
60¡ª70 |
60¡ª70 |
60¡ª70 |
Gloss |
86 |
70 |
62 |
65 |
Battering ( cm ) |
50 |
50 |
50 |
50 |
From the above table, you may find that in formulation 3, 100 g of
sericite mica replace BaSO4, the gloss is lower than formulation 4 of
10 flatting agent. However, the cost of formulation 3 is much lower
than formulation 4 .
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