In recent years, with the development of the plastics industry, many friends have transformed from traditional plastic processing to plastic modification. The modified formula seems to be simple, but it hides mystery. This requires us to be cautious when choosing plastic additives. How to get higher performance, low cost and easy processing formula, today's small series will be from the following three aspects. You introduce the choice of additives.

Select additives according to purpose

The specific selection range of additives is as follows:

Toughening

Elastomers, thermoplastic elastomers, and rigid toughened materials are selected.

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Enhance

Glass fiber, carbon fiber, whisker and organic fiber are selected.

Flame retardant

Bromines (common bromine and environmentally friendly bromine), phosphorus, nitrogen, nitrogen/phosphorus composite intumescent flame retardants, antimony trioxide, and hydrated metal hydroxides.

Antistatic

Various antistatic agents.

Conductive

Carbon (carbon black, graphite, carbon fiber, carbon nanotube), metal fiber and metal powder, metal oxide.

magnetic

Ferrite magnetic powder, rare earth magnetic powder includes samarium cobalt, NdFeB (NdFeB), strontium iron nitrogen, aluminum nickel;

Thermal conduction

Metal fibers and metal powders, metal oxides, nitrides and carbides; carbon materials such as carbon black, carbon fibers, graphite and carbon nanotubes; semiconductor materials such as silicon, boron.

Heat resistant

Glass fiber, inorganic filler, heat resistant agent such as substituted maleimide and β crystal nucleating agent.

Transparent

The nucleating agent has the best effect on the sorbitol series of α crystal nucleating agent for PP.

Wear resistant

There are three major types of cobalt magnetic powders such as graphite, molybdenum disulfide and copper powder.

insulation

Calcined kaolin.

Barrier

Mica, montmorillonite, quartz, etc.

Additives are selective for resins

Red phosphorus flame retardant is effective for Pa, PBT and PET;

Nitrogen-based flame retardants are effective for oxygen-containing materials such as Pa, PBT, PET, etc.;

Glass fiber heat-resistant modification has a good effect on crystalline plastics and poor effect on amorphous plastics;

The carbon black is filled with a conductive plastic and has a good effect in the crystalline resin;

The nucleating agent works well for the copolymerized polypropylene.

Different shapes and effects

Auxiliary shape

The reinforcing effect of the fibrous auxiliary agent is good.

The degree of fiberization of the additive can be expressed by the aspect ratio. The larger the L/D, the better the reinforcement effect, which is why we add glass fiber to the vent.

The molten state is advantageous for maintaining the aspect ratio and reducing the probability of fiber breakage than the powder.

The spherical auxiliaries have good toughening effect and high brightness.

Barium sulphate is a typical spherical auxiliaries, so high-gloss PP is filled with barium sulfate, and a small degree of rigidity and toughness can also be used.

Auxiliary particle size

Effect of additive particle size on mechanical properties:

The smaller the particle size, the more beneficial the tensile strength and impact strength of the filler material.

Effect of additive particle size on flame retardancy:

The smaller the particle size of the flame retardant, the better the flame retardant effect. For example, the smaller the particle size of the hydrated metal oxide and the antimony trioxide, the less the amount of addition to achieve the same flame retardant effect.

Effect of additive particle size on color matching:

The smaller the particle size of the colorant, the higher the coloring power, the stronger the hiding power, and the more uniform the color. However, the particle size of the colorant is not as small as possible, there is a limit value, and the limit values ​​for different properties are different. For the coloring power, the ultimate particle size of the azo colorant was 0.1 μm, and the limit particle size of the anthraquinone colorant was 0.05 μm. For the hiding power, the limiting particle size of the colorant is about 0.05 μm.

Effect of additive particle size on conductivity:

Taking carbon black as an example, the smaller the particle size, the easier it is to form a network-like conductive path, and the same conductive effect is added to reduce the amount of carbon black added. However, like the coloring agent, the particle size also has a limit value, the particle size is too small to be gathered and difficult to disperse, and the effect is not good.

Surface treatment of additives

The compatibility of the auxiliary agent and the resin should be good, so as to ensure the dispersion of the auxiliary agent and the resin according to the expected structure, to ensure the completion of the design index, to ensure the long-lasting effect of the effect in the service life, resistance to extraction, migration resistance, and precipitation resistance.

In addition to a small amount of additives such as surfactants, good compatibility with the resin is the key to its efficacy and increased addition. Therefore, it is necessary to try to improve or improve the compatibility, such as surface activation treatment with a compatibilizer or a coupling agent.

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