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 –corrosion.

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°, 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°angle 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°optic angle of muscovite is 30-50°.
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—titanium dioxide, sericite mica and other fillers

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Application In Plastic

The sericite is an excellent filler which owns lots of functions. It has got wide application for its peculiar physicochemical property and fine quality-price ratio. Application fields: thermoplastic plastics (polythene，polypropylene, nylon, polyester,ABC etc), thermoset plastics( phenol formaldehyde resin,epoxy resin etc).
Sericite reinforcing Compression Molding Thermoplastic plastics
Mechanical Performance Comparative List

Polymer Volume Fraction Wraping Strength (N/mm) Wraping ModulusS (N/mm) Filler Polythene 0.5 119.2 29.3 GC1250 Polythene 0.5 109.5 29.2 GC800 Polythene 0.5 87.4 22.5 GB800 Polythene 0.5 142.5 35.4 Super Abrasion Resistance Carbon Black Polythene 0.5 117.3 27.3 Semi-Reinfocing Carbon Black Polystyrene 0.5 150.7 43.9 GC1250 Polystyrene 0.5 147.5 42.6 GC800 Polystyrene 0.5 151.9 43.7 Semi-Reinfocing Carbon Black Polystyrene 0.5 85.7 20.9 Precipitated Calcium Carbonate Polypropylene 0.5 159.1 36.6 GC1250 Polypropylene 0.5 152.0 35.8 GC800 Polypropylene 0.5 127.3 25.7 GB800 Polypropylene 0.5 182.4 37.3 Super Abrasion Resistance Carbon Black Polypropylene 0.5 95.2 20.9 Precipitated Calcium Carbonate

Sericite Reinforcing Plastics Performance：

Item \ Performance	Test Method	PA	PP	ABS	PA6
GC-1250	Ignition Residue	30	30	30	30
Tensile Strength（MPa）	GB1040-79	125	63	87	112
Breaking Extensibility（%）	GB1040-79	3.2	2.4	3.1	2.5
Bending Strength（MPa）	GB1042-79	183	95	107	210
Bending Elastic Modulus（MPa）	GB1042-79	5800	7500	8700	9300
Impact Strength(nick)（KJ/m2）	GB1043-79	11.3	10.2	9.3	8.7
Rockwell Hardness	GB3398-82	104	107	112	83
Thermal Distortion Temp.	GB1634-79	201	152	141	210
Molding Shrinking Ratio（%）	WJ433-65	0.79	1.12	1.23	0.5

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Application In Rubber

The sericite powder has various performances when it is used for the rubber products filler. The sericite powder can improve the rubber products strength, the reinforcing efficiency is similar to carbon black and white carbon black.

Main Functions In Rubber Products:
1. Improve the rubber products strength, the reinforcing efficiency reaches the white 　　 carbon black.
2. Improve the dimension stability, stress resistance, split stability, antiage, 　　　　　 antifissuration. Reinforce the tenacity and wearable resistance.
3. Acid and basic stability, fire resistance and anticorrosion etc.
4. Improve the heating resistance , decrease the coefficient of condensation and wraping 　 ratio; promote the gas decompose penetrability and thermal expansivity.
5. mprove the electrical performance of rubber products.
6. In light and colorized rubber products, it can replace 5-30% acidic white carbon 　　　 black, It avoids the accelerant default(sorption , easy chared), reduce the sulfurated time.

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Application In Welding Rod Industry

The sericite has fine synthetical performance, it will improve the welding rod quality of E4301,E4313. The applied efficiency is better than Sea-foam, white slimes and ljardite etc.
The sericite is layer-slicelike aluminosilicate, Molecular Formula is KAl2[Si3AlO10](OH,F) , fit to the welding rod industry.

Sericite Chemical Component:

Chemical Component	SiO2	AI2O3	K2O	H2O	S	P
Content(%)	50-60	25-30	7-11	≤5	≤0.03	≤0.03

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Application In Other Industries

1． Ceramic Industry

2． Paper Industry

3． Refractory

4. Constructional Material

5． Fine Chemical And Cosmetic Industry