Polypropylene sealing strip
10.5 Polypropylene sealing strip
Polypropylene sealing strip is the most widely used type of plastic sealing strip. Polypropylene sealing strips have the characteristics of good strength, stable electrical and chemical properties, good wear resistance, vibration resistance and moisture resistance, and light weight. The modified polypropylene sealing strip also has the characteristics of cold resistance, high temperature resistance, and good dimensional stability.
The use of polypropylene sealing strips is mainly for static sealing at the junction between two parts. Sealing of joints between various components such as pipelines, mechanical parts, and building components. It can prevent the leakage or immersion of internal and external media (such as liquid, gas, or dust), prevent mechanical vibration, insulation, etc., and achieve sealing.

(1) Raw material selection
The raw material used for the molding of polypropylene sealing strips is mainly polypropylene resin. Depending on the application environment conditions of the sealing strips, a certain proportion of auxiliary materials such as antioxidants, stabilizers, and fillers can also be added to the resin. The reference formula for the raw materials used for the formation of polypropylene sealing strips is as follows.
① Formula 1 (mass fraction)
100 parts polypropylene resin (PP), 40 parts talc powder, 5 parts chlorinated paraffin, and 1 part dibutyltin dilaurate-
② Formula 2 (mass fraction)
100 parts polypropylene resin (PP), 5 parts polyisobutylene (PIB), 15 parts zinc oxide, 15 parts antioxidant MBs, 0.3 parts antioxidant (264), 0.5 parts antioxidant (1010), 0.3 parts melamine, and 0.5 parts zinc stearate (ZnSt).

(2) Forming method
The extrusion molding method for polypropylene sealing strips is relatively simple. The raw materials used for sealing strip molding are measured according to the formula requirements, mixed together and evenly mixed, and then mixed and granulated by an extruder; After being plasticized and melted by an extruder, it is extruded by a molding mold, cooled and shaped by water, and then rolled up to complete the extrusion molding production of PP sealing strips. The production process sequence of PP sealing strips is as follows.
Measure various raw materials separately according to the formula requirements → mix them together and mix evenly → mix and granulate with an extruder → plasticize and melt the raw materials with an extruder → form the molding mold → cool and shape → pull → roll up

(3) Equipment conditions
① A mixer can be used in any structural form to mix and stir various raw materials evenly after measurement.
② The length to diameter ratio of the extruder screw for granulation is 20:1, and the compression ratio is 3:1.
③ The single screw extruder can be selected for PP resin plasticizing special plastic profiles. The screw diameter of the extruder is φ 45mm, aspect ratio ≥ 20:1.
④ The structure of the forming mold is similar to that of the packaging belt forming mold. The only difference is that the cross-sectional shape of the mold lip at the melt outlet needs to match the cross-sectional dimensions of the sealing strip. The structure of the cooling water tank and traction device is also the same as the auxiliary equipment in the packaging belt.

(4) Process temperature
The extrusion process temperature for PP sealing strip molding raw materials is 150-170 ℃ in the barrel feeding section, 170-200 ℃ in the plasticizing section, 200-210 ℃ in the homogenizing section, 200-210 ℃ in the molding mold temperature, and 20-40 ℃ in the cooling and shaping water tank.

Company:Wuhan Handern Machinery Co.,Ltd.
Add:No.61 Yinbo Road,Jinghe Street,Dongxihu,Wuhan,Hubei,China
Website：handern.en.alibaba.com
handern.1688.com
tel:8613986280012
WhatsApp: +8613986280012

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