The English name of PFA is: Polyfluoroalkoxy, which is similar to PFAFEPPTFE in chemical properties, but FEP can only be used below 200 degrees, and PTFE cannot be injected.

Specific gravity: 2.13-2.167g/cm3

Molding shrinkage: 3.1-7.7%

Molding temperature: 350-400 ℃

Features and main uses of PFA:

PFA is commonly known as meltable PTFE, and various properties are the crown of fluorine plastics. Widely used in the semiconductor industry, as well as medical, chemical anti-corrosion, automotive and other fields.

Material properties:

1. It is a copolymer of a small amount of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene. The melt cohesiveness is enhanced, the solution viscosity is reduced, and the performance is unchanged compared with PTFE. This kind of resin can be directly processed into products by ordinary thermoplastic molding methods.

2, long-term use temperature -80 -- 260 degrees, has excellent chemical resistance, corrosion resistance to all chemicals, friction coefficient in the lowest plastic, there are good electrical properties, its electrical insulation is not affected by temperature, "plastic king" said.

3, its chemical resistance is similar to polytetrafluoroethylene, better than vinylidene fluoride.

4, its creep resistance and compression strength are better than PTFE, high tensile strength, elongation up to 100-300%. Good dielectric properties, excellent radiation resistance.

5, non-toxic: with physiological inertia, can be implanted in the human body.

Level V0:

1, suitable for the production of corrosion-resistant parts, wear parts, seals, insulation parts and medical equipment parts.

2, high temperature wire, cable insulation, anti-corrosion equipment, sealing materials, pump valve bushing, and chemical containers.

　　PFA GranulesForming performance

1, crystalline material, moisture absorption is small. It can be processed into products by common thermoplastic processing methods.

2, poor fluidity, easy to decompose, decomposition of corrosive gas. It is advisable to strictly control the molding temperature not to exceed 475 degrees, the mold should be heated to 150-200 degrees, and the resistance of the gating system to the material flow should be small.

3. Translucent pellets, injection molding, extrusion molding. The molding temperature is 350-400 degrees, and more than 475 degrees is easy to cause discoloration or bubbles. And note that demoulding will be more difficult.

PFA particles are a kind of very important new fluorine-containing resin. Its chemical stability, physical and mechanical properties, electrical insulation properties, lubricity, non-tackiness, aging resistance, non-flammability and thermal stability are very excellent. Similar to PTFE, its high temperature mechanical strength is about 2 times higher than PTFE. In addition, it can be processed by extrusion, blow molding, injection molding and other general thermoplastic molding processes. This is because the PFA composition contains 1wt%-10wt% of perfluoropropyl vinyl ether (PPVE), which significantly improves the flexibility of the polymer chain of PFA, reduces the crystallinity of PFA, and makes PFA have good thermoplasticity. The melt viscosity of 109 poise is reduced to about 104-106 poise, which overcomes the disadvantage of difficult processing of polytetrafluoroethylene.

At present, there are four main manufacturers in the world: DuPont, Daikin, AsahiGlass and Dyneon. In 2002, the global consumption was about 5kt/a, 80% of which was used in semiconductor manufacturing industry.

PFA particle polymerization process:

In a 1L stainless steel autoclave, vacuum was applied to remove O2 and stirring was started. After adding 800ml of perfluoro-N-methylmorpholine (PFNMM), 0.38g of ethane chain transfer agent and 20ml of PPVE, the temperature was raised to 60 ° C., the stirring speed was 1000r/min, TFE was passed until 0.5MPa, and then 10 ml of FC-ll3 solution of diperfluoropropionyl peroxide was injected by pump to start the polymerization reaction. During the polymerization, TFE was continuously added, maintaining the pot pressure between 0.5 and 0.6MPa; the initiator solution was continuously injected at a rate of 0.5 ml/min. After completion of the polymerization, the polymer slurry was cooled, vented and discharged. After volatilizing most of the solvent at room temperature, it was heated to 150 ° C. and the residual solvent was driven off by air to obtain 14.3g of resin. The PFA was analyzed to have a melt viscosity of 2.55x 10 poise and a PPVE content of 4.44wt%.

After the PFA particles are synthesized, a post-treatment process of unstable end groups is required to convert the unstable end groups into stable end groups to prepare high-purity PFA. The unstable end groups can be converted into two types of stable end groups:-CONH2,-CF3, and accordingly, there are two methods for treating the unstable end groups:(1)NH3 and ammonium salt treatment of PFA;(2) fluorine gas treatment of PFA.

This article comes from:www.tflpfa.com

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