Application of PTFE ultrafine powder in engineering plastics

2022-01-01   Pageview:318

Polytetrafluoroethylene (PTFE) ultrafine powder is a low molecular weight micron-level PTFE white ultrafine powder obtained by special methods, molecular weight is generally 10 000 ~ 30 000 (suspension grade PTFE molecular weight is up to millions). It not only maintains the excellent characteristics of PTFE, but also has many unique properties, such as high crystallinity, good dispersion, easy to mix with other materials evenly, so it is widely used in the blending modification of polymer materials to improve the lubricity, wear resistance, non-stick and flame retardancy of the substrate, so that the performance of the substrate is significantly improved.

 Polytetrafluoroethylene superfine powder characteristics

1, Cold and heat resistance, the use of a wide range of temperature, in -200 to 260 degrees, the nature of almost no change.

2, chemical inertness, almost all chemicals and solvents except alkali metals are stable.

3, non-stick, in all solid materials, surface energy is the smallest, with excellent non-stick and mold release.

4, Excellent flame retardancy and weathering performance, very low combustion heat, also will not form second degree of cargo. In outdoor use will not appear oxidation, surface pollution, discoloration and quality deterioration and other circumstances.

5, scratch resistance, choose the appropriate model, not deformed scratch and rub resistance performance is excellent.

Modified plastics with PTFE ultrafine powder is obtained through a special synthesis method of low molecular weight PTFE polymer ultrafine powder. It is suitable for adding to various engineering plastics, non-stick coatings, rolled steel coatings, powder coatings, inks, lubricants and greases.

The modification of engineering plastics by PTFE blending modifier is mainly focused on two aspects: anti-wear lubrication and anti-dripping flame retardant.

1. Abrasion reduction lubricant.

The surface friction coefficient of most engineering plastics is high, and external lubricants are required in sliding friction situations, which limits the application of engineering plastics in situations where external lubricants are not allowed. The surface energy of PTFE is very low and has excellent self-lubricating properties. By blending PTFE with engineering plastics, oil-free lubricating composites with low surface friction coefficient can be prepared.

The Teflon friction reducing lubricant used for engineering plastics modification is the ultra-fine powder of Teflon with molecular weight of 30,000~200,000 and average particle size less than 30 microns, also called Teflon micro powder. The properties of PTFE micro powder such as temperature range, weather resistance, chemical stability, self-lubrication and non-stick are exactly the same as those of high molecular weight PTFE resin. While maintaining the original performance, PTFE micro powder also has the advantages of good dispersion, easy to mix with other materials and other advantages, is an excellent performance modifier.

2. Anti-drip agent.

With the continuous expansion of engineering plastics applications, its products to PTFE anti-drip agent into three categories: pure powder type, emulsion type and core shell type.

(1) pure powder type.

Pure powder type anti-dripping agent is pure PTFE particles, by sintering the surface of the particles to improve the dispersion and fluidity of PTFE, when the anti-dripping agent and plastic for premixing, can show better dispersion performance and avoid early fibrosis.

The advantage of pure powder type anti-dripping agent is that the content of PTFE is 100%, no other impurities are introduced, and a relatively large amount can be added.

(2) Emulsion type.

Emulsion type anti-dripping agent is made by dispersing PTFE in water under the action of dispersant to make PTFE dispersion emulsion. Because the emulsion contains a lot of water, so the use of equipment and technology requirements are higher, affected by this, China’s domestic engineering plastics to change the surname manufacturers use less emulsion-type anti-dripping agent.

(3) Core-shell type.

Core-shell type anti-dripping agent is a layer of polymer wrapped around the outside of the PTFE particle, so that it has better dispersion in the process of mixing with the plastic resin. The external coating of the shell polymer is generally polyacrylonitrile, polystyrene and polymethyl methacrylate.

Compared with pure powder type and emulsion type anti-drip agent, core-shell anti-drip agent has the advantages of good dispersion, easy to use, no agglomeration at room temperature, easy storage, no crystal point on the surface of the product, and high surface finish. However, the outer coating polymer is an impurity for the final product, which will have a certain impact on the product performance.

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