Introduction of Dispersant for Plastics

June 15, 2018

 

Dispersant is an interfacial active agent with both hydrophilic and hydrophilic properties. The solid particles of inorganic and organic pigments which are difficult to dissolve in liquid can be uniformly dispersed. At the same time, the settling and condensation of solid particles can be prevented and the medicament required for the formation of stable suspensions can be formed.

 

Product Classification:

 

1, Fatty acids, Aliphatic amides and Esters

 

The use of stearamide and higher alcohols can improve lubricity and thermal stability. The amount of stearamide (mass fraction,similarly hereinafter, 0.3%- 0.8%) can also be used as a sliding agent for polyolefin; hexenyl bis-stearamide, also known as ethylbis-stearamide, is a high melting point lubricant. The dosage is 0.5% to 2%; monoglycerol stearate, glycerol tristearate; oleic acid 0.2%-0.5%; solid hydrocarbon paraffin, melting point 57-70 ℃, insoluble in water, soluble in organic solvents. Its dispersibility, thermal stability and compatibility in resins is poor and the dosage is below 0.5%.

 

2, Paraffin

 

Although paraffin is an external lubricant, it is a nonpolar straight chain hydrocarbon and cannot wet the metal surface, that is, it cannot prevent the adhesion of PVC and other resins to the metal wall. Only when the paraffin is combined with stearic acid and calcium stearate can the synergistic effect be brought into play.

 

Liquid paraffin: freezing point -35 ~ -15 ℃, when applied to extrusion and injection molding, the compatibility with resin is poor, the addition amount is generally 0.3% -0.5%, when excessive, the processing performance becomes worse.

 

Microcrystalline wax: obtained from petroleum refining process, with relatively large molecular weight and many isomers with melting point of 65-90 ℃, good lubricity and thermal stability, but poor dispersibility. The dosage is generally 0.1% to 0.2%, preferably used together with butyl stearate and high fatty acid .

 

3, Metal Soap

 

The metal salts of high fatty acids, called metal soaps, such as barium stearate for a variety of plastics, are about 0.5%; zinc stearate is suitable for polyolefin, ABS and so on, with dosage of 0.3%; calcium stearate is suitable for general plastics, external lubrication, 0.2%-1.5%, and other stearic acid soap include cadmium stearate, magnesium stearate, and copper stearate.

 

4, low molecular wax

 

Low-molecular-weight wax is a series of oligomers with different properties, which are made of polyethylene (homopolymers or copolymers), polypropylene, polystyrene or other polymer modifiers as raw materials through cracking and oxidation.

 

Its main products are: homopolymer, oxidized homopolymer, ethylene-acrylic copolymer, ethylene-vinyl acetate copolymer, low molecular ionomer, etc. The chemical name of polyethylene wax is polyethylene glycol, and the English name is usually PEGG (Poly Ethylene Glycoll).

 

Product function:

 

1. To improve the gloss and increase the gloss of leveling effect, which is mainly determined by the scattering of light on the surface of the coating (that is, a certain degree of smoothness);

 

2, Prevent floating color hair flowers;

 

3, Improve the coloring force. But the coloring force is not necessarily as high as in the automatic toning system.

 

4, Reduce viscosity and increase pigment loading;

 

5, Reduce flocculation is like this, but the finer, the particles are, the higher, the surface energy  is. the higher adsorption strength of dispersant is needed. But the higher the adsorption intensity is, the more disadvantageous the coating performance may be.

 

6, Increase the stability of storage;

 

7, Increase color spread, increase color saturation

 

8, Increase transparency (organic pigments) or shading power (inorganic pigments).

 

Purchase requirements:

 

1, Good dispersion property to prevent filler particles from aggregating each other;

 

2, Suitable compatibility with resin and filler, and good thermal stability;

 

3, Good fluidity of molding process, not causing color drift;

 

4, Not affectting the performance of the products, non-toxic, cheap;

 

5, The amount of dispersant is generally 5% the mass of master batch.

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