丁腈橡胶

Nitrile butadiene rubber is obtained from emulsion polymerization of butadiene and acrylonitrile. Nitrile rubber is mainly produced by low temperature emulsion polymerization. It has excellent oil resistance, high wear resistance, good heat resistance and strong adhesion. Its disadvantages are poor low temperature resistance, poor ozone resistance, poor insulation performance and slightly low elasticity. Nitrile rubber is mainly used to manufacture oil resistant rubber products. NBR is a synthetic rubber prepared by copolymerization of butadiene and acrylonitrile. It is a synthetic rubber with good oil resistance (especially alkane oil) and aging resistance. Acrylonitrile content (%) in nitrile rubber includes 42 ~ 46, 36 ~ 41, 31 ~ 35, 25 ~ 30 and 18 ~ 24. The higher the content of acrylonitrile, the better the oil resistance, but the cold resistance decreases accordingly. It can be used in air at 120 ℃ or oil at 150 ℃ for a long time. In addition, it also has good water resistance, air tightness and excellent bonding performance. It is widely used to make various oil resistant rubber products, a variety of oil resistant gaskets, gaskets, sleeves, flexible packaging, flexible hose, printing and dyeing rubber rollers, cable rubber materials, etc. it has become an essential elastic material in automobile, aviation, petroleum, copying and other industries.

基本信息

中文名

丁腈橡胶
外文名

Nitrile Butadiene Rubber

成分

丁二烯和丙烯腈
制作方法

低温乳液聚合法

目录	1基本简介 2性能 3NBR结构 4NBR性能	5主要用途 6质量指标 7并用 8发展分析	9制作加工 10粉末NBR 11配方设计 12划分标准

折叠编辑本段基本简介

折叠
性能

折叠

折叠
NBR性能

折叠基本性能

折叠一般性能

Nitrile rubber has good heat resistance. Its heat resistance is better than natural rubber, CIS butadiene rubber and styrene butadiene rubber. The long-term service temperature can reach 100C and 120c for 40 days.

① Ozone resistance is worse than Cr and better than Nr

② Through reinforcement, the rubber has better physical and mechanical properties and wear resistance

③ When the content of acrylonitrile butadiene rubber is 39%, the air tightness is equivalent to that of IIR rubber

④ Low temperature flexibility general

⑤ Excellent antistatic performance

⑥ The plasticization effect of polar lipids is better

⑦ It has good compatibility with polar substances, such as PVC, acrylic resin and nylon

⑥ Poor package, low self-adhesion and large heat generation in the mixing process

Excellent oil resistance

Nitrile rubber is one of the most representative rubbers with excellent comprehensive properties such as oil resistance, physical and mechanical properties and chemical resistance. Effective use of these properties can make it meet various applications. In general purpose rubber, NBR rubber has better resistance to benzene, petroleum based oil and non-polar solvent than NR, SBR, IIR and other non-polar rubber, and also better than polar Cr, but the performance of polar solvent and polar oil of nitrile rubber is not good enough. Figure 1-1 shows the position of nitrile rubber (NBR) and other rubbers in oil and heat resistant rubber materials.

Effect of ACN content on properties

With the increase of ACN content, the polarity of NBR increases, the chain flexibility decreases, the inter chain interaction increases, the double bond content in the molecular chain decreases and the saturation degree increases, which also leads to a series of performance changes, the oil resistance, air tightness and wear resistance are improved, while the processability and cold resistance are decreased. Therefore, NBR with appropriate ACN content should be selected according to the type and service condition of nitrile rubber sample [7]. Relationship between properties of nitrile rubber and ACN content.

折叠
质量指标

指标名称	NBR1704	NBR2707	NBR3604	NBR3606	N230S	N240S
结合丙烯腈的质量分数/%	17~20	27~30	36~40	36~40	33.5~36.5	24.5~27.5
挥发分/%≤	1.0	1.0	1.0	1.0	0.75	0.75
灰分/%≤	1.5	1.5	1.5	1.5	-	-
防老剂D/%≥	1.0	1.0	1.0	1.0	-	-
拉伸强度/MPa≥	24.5	27.5	29.4	29.4	20.1	18.7
永久变形/%≤	17	28	30	30	-	-
溶胀率/%≤	70	38	20	20	-	-

折叠
并用

Nitrile rubber has very strong polarity and generally has poor compatibility with other polymers, but it has good compatibility with highly polar polymers such as neoprene, modified phenolic resin and polyvinyl chloride, especially with polymers containing chlorine, and is often used in combination. In addition, in order to improve processability and service performance, nitrile rubber is often used together with non-polar rubber such as natural rubber, styrene butadiene rubber and CIS polybutadiene rubber. It should be pointed out that nitrile rubber is characterized by good oil resistance. When used with other polymers (except polyvinyl chloride), there is a trend to reduce oil resistance.

High performance hydrogenated nitrile rubber

With the development of automobile industry, strict requirements are put forward for the heat resistance, oil resistance and chemical corrosion resistance of sealing materials used in automobile fuel and lubrication system and engine, such as rubber. For a long time, nitrile rubber with good oil resistance has been used in the automotive industry. Due to its own defects, it can only be used below 120 ℃ for a long time; Moreover, due to poor ozone resistance, weather resistance and radiation resistance, it can not meet the sealing requirements of motor vehicles such as automobiles. Hydrogenated nitrile rubber (HNBR) is the hydrogenation product of nitrile rubber. It not only has good oil resistance, ozone resistance, wear resistance and chemical corrosion resistance, but also has good compression permanent deformation, heat resistance and low temperature resistance. It can be used to manufacture sealing products used under harsh conditions.

折叠
发展分析

折叠状况

Due to its excellent oil resistance, heat resistance and physical and mechanical properties, nitrile rubber has become the standard elastomer of oil resistant rubber products. It is widely used in the fields of automobile, aerospace, oil exploitation, petrochemical, textile, wire and cable, printing and food packaging. At present, the domestic production is insufficient, and the annual import volume is about 40000 tons. In 2001, the global total annual production capacity of nitrile rubber was about 650000 tons, distributed in 17 countries and regions. Among them, the annual output capacity of China's surrounding areas is about 270000 tons, accounting for 40% of the world's total annual output capacity. Except India, they are all China's main import sources. At present, China has 3 sets of installations: first, the former China Soviet Union introduced the high temperature intermittent emulsion polymerization technology, which has an annual capacity of about 4 thousand and 500 tons, and can produce 3 brands. The two is the nitrile rubber plant modified by PetroChina Jilin Chemical Company from 1 production lines imported from styrene butadiene rubber plant in Japan. It adopts multi pot series and low temperature emulsion polymerization process, with an annual output capacity of 10 thousand tons, which can produce 5 brands. The three is Lanzhou Chemical Company introduced from Japan 15 thousand tons annual low temperature emulsion polymerization device, can produce high, medium and low nitrile content of 9 grades of soft rubber. In 2002, the production capacity of nitrile rubber in China was 29500 tons, the output was 25000 tons, and the operating rate was about 85%.

The biggest use of nitrile rubber is to produce oil resistant rubber hose and flame retardant conveyor belt, and its consumption accounts for about 50% of the total consumption; The second is sealing products, about half of which are automobile sealing products; It is also used in wire and cable, adhesive, printing and luggage products. In addition, the blending modification of nitrile rubber with other materials has become a research hotspot. Blending products such as nitrile rubber / polyvinyl chloride, nitrile rubber / polypropylene, nitrile rubber / ethylene propylene rubber, nitrile rubber / polystyrene, nitrile rubber / chlorosulfonated polyethylene, nitrile rubber / polyamide and nitrile rubber / butyl rubber can be prepared by using dynamic vulcanization technology. Among them, nitrile rubber / polyvinyl chloride blend rubber is the most widely used and is mainly used in wire and cable industry. With the rapid development of communication industry, it has strong competitiveness in the field of submarine cable to ethylene propylene rubber / polypropylene. At present, there are nearly 10000 wire and cable enterprises in China, and the annual consumption of nitrile rubber / PVC is very large. In addition, the blend rubber can also be used for outer rubber of oil pipe and fuel pipe, automobile waterproof seals and molded parts, foaming insulation layer, rubber ring, protective coating, etc.

With the completion and operation of the new unit of Lanhua company in 2000, the annual output of nitrile rubber in China is increasing year by year, and the market share is also increasing. The domestic demand is also increasing rapidly, the increase of output still can not meet the rapidly growing demand, and a considerable amount of imports are still needed every year. In 2000, the domestic output was 8600 tons, the import was 34500 tons, and the consumption was 43100 tons. The market share of domestic products was about 19.8%; In 2001, the domestic output was 21900 tons, the import was 45600 tons, the consumption was 67500 tons, and the market share of domestic products was 32.4%; In 2002, the domestic output was 25000 tons, the import was 37100 tons, and the consumption was 62100 tons. The market share of domestic products was 40%. China's imported products mainly come from Japan, South Korea, Russia and Taiwan Province of China, with 10 varieties of imported brands. According to the statistics of China Petroleum and chemical association, from 1995 to 2002, the average annual consumption growth rate of nitrile rubber in China is about 12%. It is expected that the domestic demand will still maintain an average annual growth rate of about 8% from 2003 to 2005, and the domestic demand of nitrile rubber will reach 70000 tons in 2005. Not only in terms of quantity but also in terms of varieties, China can not meet the demand. Even if all three sets of devices operate at full load, they only account for about 40% of the total consumption, and the gap is greater in terms of varieties and brands. At present, China can only produce more than 10 varieties, and the demand reaches dozens of varieties. Therefore, the development of domestic nitrile rubber industry has a long way to go.

折叠
制作加工

折叠制作

Nitrile rubber was first studied in Germany in 1930 and made into butadiene and propylene in 1931

Nitrile copolymer was found to have excellent oil resistance, aging resistance and wear resistance. In 1937, it was put into industrial production by German i.g. faben company and came out under the trade name Bunan. In 1941, the United States also began mass production. Shortly after that, some countries began to produce nitrile rubber, and many countries in the world can produce various brands of nitrile rubber. In addition to excellent oil resistance, nitrile rubber also has the characteristics of aging resistance, wear resistance, low permeability and high cohesion, so its application fields are various. The proportion of nitrile rubber demand in total rubber demand varies with the specific situation of each country. Generally, the proportion of advanced industrial countries accounts for about 2.5 ~ 3.5%, and the proportion of developing countries is slightly lower.

Preparation method

（1） Raw materials

Butadiene and acrylonitrile are monomers for polymerization of nitrile rubber. Auxiliary raw materials for polymerization are as follows.

Polymerization initiator: inorganic peroxide (such as persulfate) is used for thermal polymerization; Cold polymerization uses redox initiators (such as the catalytic system in which hydrogen peroxide and divalent iron salt coexist). The degree of polymerization regulator is long-chain alkyl sulfuric acid, and the emulsifier is anionic surfactant, rosin acid soap and fatty acid soap. The electrolyte is potassium chloride, sodium phosphate and sodium sulfate. The polymerization terminators are hydroquinones, dimethyl dithiocarbamates, etc.

（2） Aggregate

Emulsion polymerization is widely used in NBR manufacture, and solution polymerization is also used. The introduction of the emulsion gathering method is as follows.

1. Formula and process conditions

The polymerization formula and process conditions are shown in table 7-2 and table 7-3.

2. Polymerization process

(1) The preparation of hydrocarbon phase, aqueous phase and additives will mix a certain proportion of butadiene and acrylonitrile evenly to make hydrocarbon phase. Sodium hydroxide, sodium pyrophosphate, triethanolamine and soft water are added into the emulsifier to make the aqueous phase. And prepare initiator for use. The hydrocarbon phase and water phase are mixed in a certain proportion and sent to the emulsification tank. After full emulsification under stirring, they are sent to the polymerization kettle.

(2) Polymerization: the initiator is directly added into the polymerization kettle, the polymerization reaction is carried out in the kettle at a certain temperature, and then the regulator is added in batches to adjust the molecular weight of rubber. When the polymerization reaction reaches the specified conversion, a terminator is added to terminate the reaction, and the slurry is unloaded into the intermediate storage tank.

(3) After degassing, the terminated slurry is sent to the degassing tower, where butadiene is flash evaporated under reduced pressure, and then heated and evaporated by steam

Note: the polymerization temperature is 13 ℃.

Free acrylonitrile is removed by vacuum. Butadiene is recycled after compression and pressure rise, and acrylonitrile is reused after recovery and treatment.

(4) postprocessing, after degassing, the pulp is added with antioxidant D. After filtration, the gel is filtered and gathered with salt water to form granular rubber. After washing, the water is removed by extrusion and dried by drying machine, and then finished rubber is obtained. The moisture content of the dried rubber shall be less than 1%, and the finished rubber generally weighs 25kg per package.

折叠加工

Plastic refining characteristics

Soft nitrile rubber with Mooney viscosity below 65 generally does not need to be plasticized, while hard nitrile rubber with Mooney viscosity of 90-120 has low plasticity and poor processing performance. It should be fully plasticized before processing. Generally speaking, it is difficult to plasticize because of its large toughness, intense shrinkage and large heat generation. The plasticizing of nitrile rubber should be thinned by a mixer, and the simplification temperature (preferably 30-40 degrees), the compilation distance (0.5 to l.oinm) and the capacity (about 1 / 2-1 / 3 of natural rubber) should be reduced as much as possible. Strengthening cooling effect (such as cold air circulation device) and segmented plastic smelting are adopted to improve the plastic smelting effect. Generally, high ACN nitrile rubber can meet the processing requirements, while low ACN content and ACN content nitrile rubber need segmented molding to achieve beam efficiency. The process conditions of segmented molding (taking xk360 open mill as an example) are generally: cat distance of 0.5 - 1.0mm and temperature of 40-5 (RC, capacity 10-5kg, plastic refining in sections, each period of 25min, medium parking for 3-4 hours, after three-stage plastic refining, the plasticity reaches about 0.3 Vickers. Powdered admixture is conducive to the plastic refining of nitrile like rubber, and the coarser the particles, the greater the effect (such as coarse particle carbonate clock, etc.) Therefore, when the film surface is not smooth after several times of plasticizing, powder can also be added to improve the plasticity of the rubber. When acetic plasticizers such as dibutyl phthalate and dioctyl phthalate are added during plasticizing, the plasticity can also be significantly improved. Plasticizers also promote the plasticizing effect of butanoladong rubber, including accelerator M and dibenzamide group Phenyl two sulfides and two benzoyl sulfides. When nitrile rubber is formed at high temperature, the gel will be formed, so it can not be used in the mixer.

Mixing characteristics of nitrile rubber

The processing characteristics of nitrile rubber largely depend on the content of ACN. The atmosphere group strengthens the intermolecular force, reduces the flexibility of molecular chain, and makes macromolecules easy to produce network structure or branched chain. These structural characteristics affect the mixing. The mixing energy consumption of nitrile rubber is high, and the mixture is difficult to disperse in the rubber, which may be related to the large intermolecular force.

The viscosity of nitrile rubber is higher than that of ordinary rubber. The Mooney viscosity of rubber with 26-40% acrylonitrile content is 90-120. The energy consumption of rubber processing is directly proportional to the viscosity of raw rubber. Nitrile rubber has a large heat generation during mixing, which is different from isoprene rubber and styrene butadiene rubber. This kind of rubber often has a structural effect when mixed under the action of high temperature and high mechanical stress. Therefore, it will be conductive under the conditions of heating up and prolonging mixing time When viscosity is increased, adding high activity and high carbon black structure, such as quick pressing furnace black, high wear resistant furnace black and super wear-resistant furnace black, the viscosity of rubber increases more, and the gel is formed, and the processing is difficult.

For low-speed mixing, the heat generation of rubber is low, so an internal mixer or mixer with a speed of 10-20r / min should be used for mixing, and the process conditions and operation methods such as small auxiliary distance, low-speed ratio and batch feeding should be used. For nitrile rubber, special process measures to reduce the rubber temperature are often adopted: carbon black and softener are added to the internal mixer at the same time, which can slow down the structural degree and prolong the scorching time, However, the dispersion of the compounding agent is slightly reduced. When the amount of carbon black is higher than 80 phr, it should be added in three times to reduce the degree of structure and improve the rubber properties. It is difficult to disperse sulfur in nitrile rubber. It is best to add it in the internal mixer at the initial stage, so that the dispersion can be increased by 10%, and the promoter is finally added in the open mixer.

(1) Open refining

Nitrile rubber has the following characteristics when it is opened:

1) Raw rubber is not easy to pack and edit. Adding powder after packing and editing is easy to take off the jurisdiction for the second time.

2) Due to the large cohesive energy of raw rubber, the powder is not easy to mix.

3) The mixing time is longer, about twice as long as that of natural rubber.

4) The heat generated is large, and the glue temperature is easy to rise.

According to these characteristics, the roll temperature of 40-45 ° C shall be maintained for nitrile rubber mixing, and the rubber loading capacity shall be low, which shall be 70% - 80% of that of ordinary synthetic rubber. The optimum separation distance is 3mm-4mm. The powder is added in batches. Generally, sulfur, zinc oxide, solid softener and plasticizer shall be added first. After the rubber is softened, antioxidant and active agent shall be added. Carbon black and liquid softener should be added in batches to avoid sticking auxiliary, and finally add accelerator. In order to avoid coke burning, the powder should be added and slightly turned over, i.e. removed for cooling, and finally thinned and turned over.

(2) Internal mixing

Mixing nitrile rubber with internal mixer can improve production efficiency and operation conditions, and the mixing effect is good. The mixing temperature of nitrile rubber must be strictly controlled and fully cooled, and the rubber discharge temperature shall not exceed 130c.

1. Plastic refining

Plasticity, also known as plasticity, is a idiom that represents the rheological properties of unvulcanized rubber (raw rubber and compound rubber), also known as plasticity. Plasticity refers to the deformation of rubber caused by external force. When the external force is removed, its deformation property is preserved. The plasticity of raw rubber is usually expressed by Williams method, and its value ranges from 0 to 1. The larger the value, the higher the plasticity.

2. Mixing

During the mixing of nitrile rubber, due to the large internal friction and heat generation, the mixing is the same as the plastic mixing. It is appropriate to use small roll distance and low roll temperature. It is difficult to disperse sulfur in nitrile rubber. People should be added at the initial stage of mixing, but the accelerator is still added at the end. The mixing process of nitrile rubber is as follows: roll temperature is 40-45r-, roll speed ratio is 1:1.1-1.2, roll spacing is 3-4mm, rubber loading capacity is 70% - 80% of ordinary synthetic rubber, and the feeding sequence is: raw rubber - sulfur - zinc oxide, stearic acid - 1 / 2 carbon black - 1 / 2 plasticizer - 1 / 2 carbon black - 1 / 2 plasticizer - accelerator - Rubber tamping and mixing - sheet discharging.

3. Press out

Nitrile rubber is prone to scorch when pressed out. If the surface of the extrudate is rough or layered peeling after vulcanization, it is mostly caused by scorch. Extrusion process of nitrile rubber: barrel and screw temperature 40-60 ℃, die temperature 80-90t, and head temperature 90-100. In order to prevent scorching and ensure the smooth surface of the extrudate, the extruder screw shall be cooled with water.

4.硫化

丁腈橡胶硫化曲线平坦，硫化速度比天然橡胶慢，工业上丁腈橡胶制品的硫化温度一般为149-171t，但有时为了提高产量，缩短硫化周期，也可采用204℃以上的硫化温度。丁腈橡胶采用80-10℃的低温硫化时，硫化胶的强力可达2MPa，但硫化胶耐水性能和耐热性能不好，如果发生欠硫，则压缩变形严重，耐油性能低劣，这一硫化工艺一般不采用。

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Green butadiene rubber knowledge

丁腈橡胶

基本信息

折叠编辑本段基本简介

折叠
性能

折叠

折叠
NBR性能

折叠基本性能

折叠一般性能

折叠
质量指标

折叠
并用

折叠
发展分析

折叠状况

折叠
制作加工

折叠制作

折叠加工

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case

Green butadiene rubber knowledge

丁腈橡胶

基本信息

折叠编辑本段基本简介

折叠 性能

折叠

折叠 NBR性能

折叠基本性能

折叠一般性能

折叠 质量指标

折叠 并用

折叠 发展分析

折叠状况

折叠 制作加工

折叠制作

折叠加工

contact us

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折叠
性能

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NBR性能

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质量指标

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并用

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发展分析

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制作加工