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Application principle of dispersant

2020-09-12 09:16:12
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The function of dispersant is to use wetting dispersant to reduce the time and energy needed to complete the dispersion process, stabilize the dispersed pigment dispersion, modify the surface properties of pigment particles, and adjust the mobility of pigment particles

Shorten the dispersion time, improve the luster, improve the coloring power and covering power, improve the color development and color matching, prevent floating color, prevent flocculation, prevent sedimentation.

1. In fact, the gloss mainly depends on the light scattering from the coating surface (i.e. a certain flatness is enough). Of course, it needs the testing instrument to determine whether the coating is smooth enough, not only considering the number and shape of primary particles, but also considering their combination mode). When the particle size is less than 1 / 2 of the incident light (this value is uncertain), the gloss of the coating surface will be improved, In the same way, the covering power which depends on scattering to provide the main covering power will not increase (except for carbon black which mainly depends on absorbing light, organic pigments forget). Note: the incident light refers to the range of visible light, and it is not good to say that the leveling is good; but pay attention to the reduction of the original number of particles, which is to reduce the structural viscosity, but the increase of the specific surface will reduce the number of free resin, and it is not good to say whether there is a balance point, but the general powder coating leveling is not the finer the better.

2. Prevent floating color and blooming

3. Improve the tinting power notice that the higher the tinting power in the automatic color matching system, the better

4. Reduce viscosity and increase pigment loading

5. However, the higher the surface energy of the finer particles, the higher the adsorption strength of the dispersant is needed. However, the dispersant with too high adsorption strength may cause adverse effects on the film performance

6. In fact, the reason for increasing the storage stability is similar to the above. Once the stability strength of dispersant is not enough, the storage stability will become worse (of course, it is no problem from your picture). 7. Increase the color development, increase the color saturation. 8. Increase the transparency (organic pigment) or the hiding power (inorganic pigment)

Tego dispers, a wetting and dispersing agent of Nanjing Hanbao industrial raw materials Co., Ltd., helps the pigments to wet and stabilize, prevent floating color, blooming and pigment sedimentation, maintain stable pigment covering power and color strength during storage, and ensure maximum color yield and minimum grinding steps. Because these additives can reduce the viscosity and increase the maximum pigment concentration during dispersion, the coatings and pigment concentrates produced are more cost-effective. Tegodispers 757 W is recommended for the production of water-based pigment concentrate. For corrosion-resistant waterborne coatings, it is also the preferred product. Like tegodispers 750W and tegodispers 755w, it can meet the highest optical and rheological properties. Tegodispers 65x series is the market standard product without ethoxyalkylphenol for general color paste which is suitable for both solvent-based and water-based formula. Tegodispers 656, 670 and 685 are particularly suitable for modern solvent based formulations. In UV system, tegodispers 685 is suitable for all pigments and tegodispers 688 is suitable for matting powder. All tegodispers products are free of ethoxyalkylphenols.

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An excellent dispersant should meet the following requirements:

1. It has good dispersibility and prevents the filler particles from aggregating with each other;

2. It has good compatibility with resin and filler and good thermal stability;

3. It has good fluidity in forming process and does not cause color drift;

4. It does not affect the performance of the product; it is non-toxic and cheap.

The dosage of dispersant is generally 5% of the mass of masterbatch

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Fatty acids, aliphatic amides and esters

Stearamide can be used together with higher alcohols to improve the lubricity and thermal stability, the dosage (mass fraction, the same below) is 0.3% - 0.8%, and it can also be used as a lubricant for polyolefins; hexenyl bis stearamide, also known as ethylene bis stearamide (EBS), is a high melting point lubricant, the dosage is 0.5% - 2%; stearic acid monoglyceride (GMS), tristearate glyceride (HTG); oleic acid acyl ester dosage 2% ~ 0.5%; hydrocarbon paraffin solid, melting point 57 ~ 70 ℃, insoluble in water, soluble in organic solvents, poor dispersion, compatibility and thermal stability in the resin, the dosage is generally less than 0.5%.


Paraffin

Although paraffin is an external lubricant, it is a nonpolar straight chain hydrocarbon and can not wet the metal surface, that is to say, it can not prevent PVC and other resins from adhering to the metal wall. Only when it is used together with stearic acid and calcium stearate, can it play a synergistic effect.

Liquid paraffin: freezing point (- 15 ℃) - (- 35 ℃), in extrusion and injection molding processing, the compatibility with resin is poor, the addition amount is generally 0.3% - 0.5%, too much will make the processing performance worse.

Microcrystalline paraffin: obtained from petroleum refining process, it has large relative molecular weight and many isomers, melting point 65-90 ℃, good lubricity and thermal stability, but poor dispersibility, the dosage is generally 0.1% - 0.2%, it is best used with butyl stearate and higher fatty acid.

Metal soap

The metal salts of higher fatty acids, called metal soap, such as barium stearate (BST), are suitable for various plastics with the amount of about 0.5%; zinc stearate (znst) is suitable for polyolefin, ABS, etc., with the amount of 0.3%; calcium stearate (CAST) is suitable for general plastics with the amount of about 0.3%; and it is suitable for external lubrication 2% - 1.5%; other stearic acid soaps such as cadmium stearate (cdst), magnesium stearate (MgSt), copper stearate (cust).

Low molecular wax

Low molecular wax is a series of oligomers with different properties, which are made from polyethylene (homopolymer or copolymer), polypropylene, polystyrene or other polymer modified materials by pyrolysis and oxidation.

Its main products include homopolymer, oxidized homopolymer, ethylene acrylic acid copolymer, ethylene vinyl acetate copolymer and low molecular ionomer. Among them, polyethylene wax, whose chemical name is polyethylene glycol and English name is PEG (poly ethylene glycol) is the most commonly used

The average molecular weight of common polyethylene wax (polyethylene glycol) is 1500-4000, and its softening point is 102 ℃; the average molecular weight of other specifications of polyethylene wax is 10000-20000, and its softening point is 106 ℃; the long chain molecules of oxidized polyethylene wax have a certain amount of ester or soap groups, so the internal and external lubrication of PVC, PE, PP and ABS is relatively balanced, The effect is good and the transparency is good. Due to the variety of dispersants and the practical application environment, it is very important to choose the appropriate dispersant.

Polyethylene glycol 200 or 400 (molecular weight about 190-420) is a good dispersant / solubilizer / wetting agent / solvent for water-soluble dispersion system. Polyethylene glycol 200 or 400 is lipophilic, and can form stable dispersion system with dispersions with lower HLB value.

1、 Product performance

HPMA is a kind of polyelectrolyte with low molecular weight. Its relative molecular weight is 400-800. It is nontoxic, soluble in water, and has high chemical and thermal stability. Its decomposition temperature is above 330 ℃. At high temperature (< 350 ℃) and high pH, the solution limit effect is obvious. HPMA can be used in alkaline water or in combination with other drugs. HPMA still has good scale inhibition and dispersion effect on carbonate below 300 ℃, and the scale inhibition time can reach 100 h. Due to its excellent scale inhibition and high temperature resistance, HPMA has been widely used in the flash distillation unit of seawater desalination, neutralization and low pressure boiler, steam locomotive, crude oil dehydration, water and oil pipeline and industrial circulating cooling water. In addition, HPMA has a certain corrosion inhibition effect, and the compound effect with zinc salt is better.

HPMA can also be used as cement admixture.


2、 The quality index conforms to GB / T 10535-1997

Project indicators

Appearance: light yellow to brownish red transparent liquid

Solid content% ≥ 48.0

Bromine value mg / g ≤ 80.0

Average molecular weight ≥ 450

PH (1% aqueous solution) 2.0-3.0

Density (20 ℃) g / cm ≥ 1.18

3、 How to use it

HPMA is usually compounded with 1-15ppm organic phosphonate, which is used for circulating cooling water, oilfield water injection, crude oil dehydration and furnace treatment of low-pressure boiler. It has a good effect of inhibiting scale formation and stripping old scale, and the scale inhibition rate can reach 98%. When HPMA is combined with zinc salt, the corrosion of carbon steel can be effectively prevented.

4、 Safety and protection

HPMA is acidic. Avoid contact with skin and eyes. Rinse with plenty of water after contact.


 


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