Introduction of dispersants for plastics

Time:2022-11-28 09:04:51 / Popularity: / Source:

Dispersant is a surfactant with two opposite properties, lipophilicity and hydrophilicity in molecule. It can uniformly disperse solid particles of inorganic and organic pigments that are difficult to dissolve in liquids, at the same time prevent sedimentation and agglomeration of solid particles to form a stable suspension.

Product category

1. Fatty acids, fatty amides and esters

Stearamide can be used in combination with higher alcohols to improve lubricity and thermal stability. Dosage (mass fraction, same below) is 0.3%-0.8%, it can also be used as a slip agent for polyolefins; hexenyl bisstearic acid amide, also called ethylene bisstearic acid amide, is a kind of high melting point lubricant, dosage is 0.5% to 2%; stearic acid monoglyceride, tristearic acid glyceride; amount of oleic acid is 0.2%~0.5%; hydrocarbon paraffin wax solid, melting point is 57~70℃, insoluble in water, soluble in organic solvents, poor dispersibility, compatibility and thermal stability in resin, dosage is generally below 0.5%.
dispersants for plastics 

2. Paraffin wax

Although paraffin wax is an external lubricant, it is a non-polar straight-chain hydrocarbon and cannot wet metal surface, which means that it cannot prevent resins such as polyvinyl chloride from adhering to metal wall. Only when used together with stearic acid and calcium stearate, can it exert a synergistic effect.
Liquid paraffin: freezing point -15-35℃, it has poor compatibility with resin during extrusion and injection molding. Addition amount is generally 0.3%-0.5%. If it is too much, it will deteriorate processing performance.
Microcrystalline paraffin: It is obtained from petroleum refining process, its relative molecular mass is relatively large, and there are many isomers, melting point is 65-90℃, lubricity and thermal stability are good, but dispersibility is poor, dosage is generally 0.1 %-0.2%, best used together with butyl stearate and higher fatty acid.

3. Metal soaps

Metal salts of higher fatty acids are called metal soaps. For example, barium stearate is suitable for a variety of plastics, and dosage is about 0.5%; zinc stearate is suitable for polyolefins, ABS, etc., and dosage is 0.3%; calcium stearate is suitable for general-purpose plastics, used for external lubrication, dosage is 0.2%-1.5%; other stearic acid soaps such as cadmium stearate, magnesium stearate, copper stearate.

4. Low molecular wax

Low-molecular wax is a series of oligomers with different properties, which are made from various polyethylene (homopolymer or copolymer), polypropylene, polystyrene or other polymer modified materials, after cracking and oxidation. .
Its main products are: homopolymers, oxidized homopolymers, ethylene-acrylic acid copolymers, ethylene-vinyl acetate copolymers, and low-molecular-weight ionomers. Among them, polyethylene wax, chemical name of polyethylene wax is polyethylene glycol, and English name PEG (Poly Ethylene Glycol) is the most commonly used.

Product function

1. Improve gloss and increase leveling effect. Actual gloss is mainly determined by scattering of light on the surface of coating (that is, a certain level of flatness is enough;
2. Prevent floating color and blooming;
3. Improve tinting strength. Pay attention that tinting strength is not as high as possible in automatic tinting system;
4. Reduce viscosity and increase pigment loading;
5. This is the way to reduce flocculation, but the finer particles, the higher surface energy, and the higher adsorption strength of dispersant is needed, but dispersant with too high adsorption strength may cause disadvantages to performance of coating film;
6. Increase storage stability;
7. Increase color development and increase color saturation;
8. Increase transparency (organic pigments) or hiding power (inorganic pigments).

Product Principle

In production process of our coatings, pigment dispersion is a very important production link, which is directly related to storage, construction, appearance and performance of paint film, so reasonable selection of dispersants is a very important production link.
However, dispersion of coating slurry is not only related to dispersant, but also to formulation of coating and choice of raw materials. As name suggests, dispersant is to reasonably disperse various powders in solvent, and through a certain charge repulsion principle or polymer steric hindrance effect, various solids are stably suspended in solvent (or dispersion).

Purchase requirements

1. Good dispersion performance to prevent mutual aggregation of filler particles;
2. It has proper compatibility with resins and fillers, and has good thermal stability;
3. It has good fluidity during molding and does not cause color drift;
4. Does not affect performance of product, is non-toxic and inexpensive;
5. Amount of dispersant is generally 5% of mass of masterbatch.

Go To Top