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What is hydrogenated nitrile gum?

Hydrogenated nitrile butadiene adhesive is a highly saturated elastomer obtained by special hydrotreating of nitrile butadiene adhesive. Hydrogenated nitrile butadiene rubber has good oil resistance (good resistance to fuel oil, lubricating oil and aromatic solvent); And because of its highly saturated structure, so that it has good heat resistance, excellent chemical corrosion resistance (freon, acid, alkali with good resistance), excellent ozone resistance, high compression permanent deformation resistance; At the same time, hydrogenated nitrile butadiene rubber also has high strength, high tearing performance, excellent wear resistance and other characteristics.

Characteristics of hydrogenated nitrile butadiene adhesive

1. Although hydrogenated nitrile butadiene adhesive is saturated by hydrogenation, it has tensile crystallization and thus high strength.

2. Good heat and ozone resistance, weather aging resistance and chemical acid and alkali resistance.

3. Good resistance to swelling of alkaline liquids (including oils containing corrosive additives).

4. Good mechanical properties and high wear resistance, even in the temperature rise conditions still maintain a comparable level.

5. Remarkable wear resistance under extremely harmful conditions.

6. Excellent tensile strength.

7. Excellent compressive deformation resistance.

Preparation method of hydrogenated nitrile butadiene adhesive

There are three main preparation methods: ethylene - acrylonitrile copolymerization, NBR solution hydrogenation and NBR emulsion hydrogenation.

1. The copolymerization method

Ethylene - acrylonitrile copolymerization method, acrylonitrile - ethylene copolymerization method, because the reaction rate of each monomer in the copolymerization reaction is very different, it is difficult to control, and the performance of the polymer is not very good, this method is still in the stage of preliminary study.

2. Emulsion hydrogenation

Diimide can be obtained by thermal decomposition of p-methyl sulfonyl hydrazide, which is an effective hydrogenation reducing agent. NBR latex can directly generate HNBR under the action of oxidants such as hydrazine hydrate, oxygen or hydrogen peroxide and metal ion initiators such as copper and iron.

3. Hydrogenation of solution

Solution hydrogenation is carried out by hydrogen in hydrogenated nitrile solution with precious metals palladium, calcium and rhodium as catalysts. NBR molecular chain acrylonitrile content determines its oil resistance. When hydrogenating NBR, only the double bond of diene unit is hydrogenated selectively to reduce the saturated bond, but the side chain of acrylonitrile unit -- C≡N is not hydrogenated. Two catalysts are mainly used in this hydrogenation process, which are heterogeneous support catalyst and homogeneous matching site catalyst. When these two support catalysts hydrogenate NBR, the residue of NBR catalyst or the auxiliaries used in the polymerization reaction may adhere to the surface of the support or remain in the micropores, resulting in a sharp decline in the activity of the catalyst and affecting its reuse.

There are three kinds of uniformly matched catalysts: palladium catalyst, rhodium catalyst and iridium catalyst. Palladium catalyst is stable to water and air, convenient storage and transportation, and can be recycled repeatedly, but the activity and selectivity are poor. Iridium catalyst hydrogenated NBR has very high activity and selectivity, which has become one of the hot spots in the development of HNBR.

The difference between nitrile butadiene adhesive and hydrogenated nitrile butadiene adhesive

1. The first process of nitrile butadiene and acrylonitrile by emulsion polymerization; And hydrogenated nitrile butadiene rubber is processed on the basis of nitrile butadiene rubber, a highly saturated elastomer obtained from nitrile butadiene rubber after special hydroprocessing.

2. Heat resistance, conventional nitrile rubber use temperature is 100℃, special formula can be used at 120℃; The conventional use temperature of hydrogenated nitrile butadiene rubber is 150℃, which can be made higher, depending on the formula and raw rubber.

3. Although the oil resistance, heat resistance and wear resistance of nitrile butadiene rubber are good, hydrogenated nitrile butadiene rubber has better heat resistance, cold resistance and wear resistance, higher tensile strength and better comprehensive performance than nitrile butadiene rubber, but the price is also more expensive than nitrile butadiene rubber O-ring.

Application collar of hydrogenated nitrile butadiene adhesive

1. The automobile industry

Good dynamic performance under high temperature, used for automobile synchronous belt and exhaust pipe.

2. Oil extraction

Cyanogroup good oil resistance, resistance to various media.

3. Aerospace

High temperature resistance, 150℃ under the aviation kerosene, gasoline environment can be used for more than 1000 hours.

1. National defense industry

2. 

5. Battery diaphragm

Dispersing agent for conductive agent, positive and negative bonding material, instead of PVDF.