Raw Materials HNBR

# We sell plastic and rubber raw material # Raw Materials HNBR

Preparation of Raw Materials HNBR

There are three main methods for the preparation of HNBR: ethylene monoacrylonitrile copolymerization, NBR solution hydrogenation and NBR emulsion hydrogenation.

• Ethylene monoacrylonitrile copolymerization method

In the preparation of Raw Materials HNBR by copolymerization of acrylonitrile and ethylene, the reaction rate of each monomer in the copolymerization reaction varies greatly (rAN=0.04, rE=0.8), which is difficult to control, and the performance of the polymer is not very good, so this method is still at the stage of small pilot study.

• NBR emulsion hydrogenation

The emulsion hydrogenation method of NBR uses the thermal decomposition of p-methylsulfonyl hydrazide to produce diimide, which is an effective hydrogenation reductant. The process of preparing emulsion HNBR with diimide as a reductant was first published by WideMan in 1984, who found that NBR latex could directly generate Raw Materials HNBR under the action of oxidants such as hydrazine hydrate, oxygen or hydrogen peroxide, and metal ion initiators such as copper and iron. Parker et al. of GoodYear Rubber & Tire Company, USA, used the emulsion hydrogenation method to produce HNBR latex with the following formula (parts by mass): NBR latex, 100 g, CuSO4 5H2O: 0.008 g, sodium dodecyl sulfate: 0.15 g, defoamer, hydrazine hydrate: 15.6 g, H2O2: 16.66 g. The NBR latex, CuSO4 5H2O: 0.008 g, sodium dodecyl sulfate: 0.15 g, defoamer, hydrazine hydrate: 15.6 g, H2O2: 16.66 g were added to the reactor. HNBR was obtained by heating to 45-50℃, adding hydrazine hydrate, and then adding H2O2 and defoamer in the next 7h, and stirring at constant temperature for 1 h. Due to the high price of hydrogenated masterbatch (p-toluene sulfonyl hydrazide) and slow hydrogenation rate, this method is still in the small trial stage.

• NBR solution hydrogenation

The solution hydrogenation of NBR is carried out in NBR solution with the precious metals palladium, calcium and rhodium as catalysts and hydrogen gas.The content of acrylonitrile on the molecular chain of NBR determines its oil resistance.When hydrogenating NBR, only the double bond of the diene unit is selectively hydrogenated and reduced to saturated bonds, and the side chain eyeball group -C≡N of the acrylonitrile unit is not hydrogenated.This hydrogenation method mainly uses Two types of catalysts are used for this hydrogenation method, namely, non-homogeneous carrier catalysts and homogeneous coordination catalysts. The first non-homogeneous carrier catalyst is Pd/C catalyst with carbon carrier, which has high selectivity and hydrogenation rate up to 95.6%, but in the hydrogenation reaction, the diene rubber affinity with carbon black is easily adsorbed on the surface of carbon black, and the carbon black is easily coagulated into lumps during stirring, which will have adverse effects on the vulcanization characteristics of HNBR. The Pd/SiO2 catalysts with SiO2 as the carrier have been industrialized by Ruion, Japan. When these two carrier catalysts are used for hydrogenation of NBR, the residues of NBR catalyst or the additives used in the polymerization reaction may adhere to the surface of the carrier or remain in the micro-pores, which will cause a sharp decrease in catalyst activity and affect the reuse.

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