辐照技术在橡胶行业中的应用

2019-1-31 9:30:11

Polymers comprise the main fraction among the materials concerning radiation processing. Rubber and tire are also a big part of polymer industry. In rubber and tire industries, radiation practices are focused on vulcanization(cross-linking), pre-vulcanization, and devulcanization (for recycling rubber based wastes). 

在有关辐照处理的材料中,聚合物是主要的组成部分。橡胶和轮胎也是聚合物行业的重要组成部分。在橡胶和轮胎行业中,辐照应用集中在硫化(交联)、预硫化和脱硫(橡胶回收)。


.3APPLICATION OF RADIATION VULCANIZATION IN RUBBER AND TIRES

辐照硫化在橡胶和轮胎中的应用

The application of radiation for the vulcanization and modification of rubber is a prospective technology in polymer processing. This research began in the middle of the 20th century, and many world-famous tire manufacturers had applied radiation vulcanization technology in their plants by the end of the 2oth century. At present, more than 93% of radial tire made in Japan are treated by low-energy accelerators for prevulcanization. In recent years, EB radiation vulcanization has become gradually recognized and accepted in the rubber and tire industry in China. Some tire manufacturer have already established production lines with the adoption of radiation vulcanization.

辐照在橡胶的硫化和改性中的应用是聚合物加工中的前瞻性技术。这项研究始于20世纪中叶,许多世界著名的轮胎制造商在20世纪末已将辐照硫化技术应用于其工厂。 目前,日本有超过93%的子午线轮胎是采用低能加速器进行预硫化处理制造出来的。近年来,EB辐照硫化已逐渐被中国橡胶和轮胎行业所认可和接受。一些轮胎制造已经建立起了采用辐照硫化的生产线。

The following is the introduction of the radiation vulcanization, the effect of radiation on the rubber, and the advantages of radiation vulcanization compared with chemical vulcanization. In addition, there is a summary of the application and development of EB irradiation in the rubber and tire industry at home and abroad. Modified offline irradiation equipment for the prevulcanization process and application examples of this technique is also described.

以下是对辐照硫化的介绍和辐照对橡胶的影响分析,以及辐照硫化与化学硫化相对比的优点介绍。此外,还概述了EB辐照在国内外橡胶和轮胎行业中的应用和发展,描述了用于预硫化过程中的改进后了的离线辐照设备和技术的应用实例。

EB radiation prevulcanization has many advantages, including reducing the cost and improving the performance of tires. This technology is certainly important for the manufacture of high-performance radial tires. It has an enormous potential market in the future.

EB辐照预硫化具有许多优点,包括降低成本和改善轮胎性能。这项技术对于制造高性能的子午线轮胎至关重要,它在未来拥有巨大的潜在市场。

3.3.1 Radiation vulcanization of rubber橡胶的辐照硫化 

3.3.1.1Radiation vulcanization and prevulcanization of rubber橡胶的辐照硫化和预硫化

Free radicals are formed when rubber macromolecules are subjected to high energy rays such as EB and X-ray at normal temperatures and pressures, causing cross-linking of main chains to form three-dimensional networks, and resulting in the same level of vulcanization compared with chemical vulcanization. The process is defined as radiation vulcanization. Radiation prevulcanization means a certain degree of weak cross-linking between main macromolecular chains by adjusting the irradiation parameters. 

当橡胶大分子在常温和常压下,经受高能射线如EB和X射线辐照时会形成自由基,使主链交联形成三维网络,达到与化学硫化相同的硫化水平。该过程定义为辐照硫化。辐照预硫化是指通过调节辐照参数,使橡胶材料在主要大分子链之间进行一定程度的弱交联。

一般情况下,在聚合物被辐照时,分子间同时发生交联反应和降解反应,简单理解就是:橡胶高分子在辐照过程中,一方面通过分子间的交联而形成网状大分子,使分子量不断增大;另一方面,随着剂量的不断增大,辐照会同时导致化学键断裂,使分子量在减少,两种现象同时进行。

所以,在一定辐照剂量范围内,分子间以交联反应为主导;若辐照剂量超过一定范围,则大部分的高分子又降解成小分子。因此,辐照剂量是确定橡胶预硫化工艺的关键参数。

3.3.1.2 Radiation effects on rubber辐照对橡胶的影响

The formation of cross-linked bonds and the degradation of polymer main chains happen simultaneously during the course of polymer irradiation. The radiation cross-linking G value of common rubber is called the cross-linking yield. The G value is an important index of rubber radiation cross-linking. Table 3.2 displays the G values of common rubber. The vast majority of alkene rubbers are cross-linkable. However, many factors, including the chemical structures of polymer main chains, polymer morphology, irradiation conditions and characteristics and the amount of accessory ingredients and sensitizers in rubber can significantly affect the formation of rubber cross-linking bonds.

在聚合物辐照过程中,交联键的形成和聚合物主链的降解同时发生。普通橡胶的辐照交联G值称为交联产率(G值是橡胶辐照交联的重要指标)。 表3.2显示了普通橡胶的G值:绝大多数烯烃橡胶是可交联的。 然而,许多因素,包括聚合物主链的化学结构,聚合物形态,辐照条件和特性以及橡胶中辅助成分和感光剂的量也都可显著影响橡胶交联键的形成。


Table 3.2 Radiation cross-linking G values of common rubber表3.2普通橡胶辐照交联G值

Type       

Type

Natural rubber

天然橡胶

Butadiene rubber

丁二烯橡胶

Nitrilebutadiene rubber丁腈橡胶

Butadiene styrene rubber

丁苯橡胶

Chloroprene rubber

氯丁橡胶

Ethylenepro pylene rubber

乙烯丙烯橡胶

Silicone rubber

硅橡胶

G value

G

1.3-1.8

2-5.8

1.4

3.8

9.6

1.8

2.2

3.3.1.3 Advantages of radiation vulcanization辐照硫化的优点

After radiation vulcanization, the tearing, aging and ozone resistance properties of rubber are improved. By radiation vulcanization, full vulcanization can be achieved rapidly at normal temperature and pressure with many advantages, including speed, flexible production, energy saving and low pollution. Once the setup parameters of radiation vulcanization are established, the EB can be evenly distributed throughout the sample, leading to a uniform crosslinking density and a single network structure. Radiation vulcanization can overcome the drawbacks of chemical vulcanization, including pollution, energy consumption, time consumption, and nonuniform vulcanization.

经辐照硫化后,橡胶的撕裂,老化和抗臭氧性能得到改善。通过辐照硫化,可以在常温常压下快速实现全硫化,具有速度快,生产灵活,节能,污染小等优点。一旦确立了辐照硫化的设置参数,通过电子束(EB)均匀地辐照到整个样品中,可使其形成均匀的交联密度和单一的网络结构。 辐照硫化可以克服化学硫化的缺点,包括污染、能耗、时间的消耗和不均匀的硫化。

3.3.1.4 Radiation vulcanization of common rubber in tire industry轮胎行业中普通橡胶的辐照硫化

A variety of rubber are used in the tire industry include natural rubber(NR), isoprene rubber(IR), butadien styrene rubber(SBR), butadiene rubber(BR), ethylene-propylene diene terpolymer(EPDM), butyl rubber(IIR), chlorinated IIR(CIIR), and brominated IIR(BIIR). Radiation vulcanization of these types of rubbers is introduced briefly in the following sections.

轮胎行业中使用的橡胶种类有很多,如天然橡胶(NR),异戊二烯橡胶(IR),丁二烯苯乙烯橡胶(SBR),丁二烯橡胶(BR),乙烯 - 丙烯二烯三元共聚物(EPDM),丁基橡胶(IIR) ,氯化IIR(CIIR)和溴化IIR(BIIR)。 在以下部分中简要介绍了辐照硫化对不同类型橡胶的影响。

3.3.1.4.1 Natural rubber and isoprene rubber 天然橡胶和异戊二烯橡胶

NR is widely used in all components of tires, with the largest consumption share in the tire industry , and it can be prevulcanized by EB and y-ray. Fig. 3.15 shows that the green strength of radiation-prevulcanized NR increases with absorbed dose. Figs. 3.16 and 3.17 indicate that the properties of NR do not change significantly before and after radiation prevulcanizaing.

天然橡胶(NR)广泛用于轮胎的所有部件,在轮胎行业中具有最大的消耗份额,它是可以通过电子束(EB)和Y射线来进行预硫化的。图3.15显示,辐照预硫化天然橡胶(NR)的生胶强度随着吸收剂量的增加而增加。图 3.16和3.17表明在辐照预硫化前后天然橡胶(NR)的性质没有显著变化。

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Table 3.3 shows the properties of radiation vulcanization and sulfur vulcanization for IR compound made according to the method of ASTM D3184(1995). The Young’s modulus and tan δ of both vulcanizates are similar, as shown in Figs. 3.18 and 3.19, while the tensile strength, elongation at break, and tensile strength at 100% of radiation vulcanizate are higher than the performance of sulfur vulcanizate. This indicates that radiation vulcanization can obtain vulcanizate with good properties.

表3.3显示了(依照ASTM D3184(1995)理论来制备的)异戊橡胶分别经辐照硫化和硫磺硫化后的发生的性能变化比较。两种方法硫化的橡胶的杨氏模量和tan值相似,如图3.18和3.19所示,辐照硫化橡胶的100%定伸应力,断裂伸长率和拉伸强度均高于经硫磺硫化的橡胶性能。 这表明辐照硫化可以获得具有更好性能的硫化材料。

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3.3.1.4.2 Styrene-butadiene rubber and butadiene rubber丁苯橡胶与顺丁橡胶 

SBR is a copolymer with styrene and cis-1, 4 butadiene, and is widely used in the tread of passenger car tires and carcass compounds. It has the largest consumption share of all synthetic rubbers. Cis-1,4 polybutadiene is the most important blended rubber in the tread formula, polymerized by cis-1, 4 butadiene. The wear Resistance of BR is also the best of the common rubbers. SBR and BR can be cross-linked by irradiation, and the degradation rate for both is close to zero when they are irradiated in vacuum. The mechanical properties of SBR compound measured according to ASTM D3185(2006) for rubbers vulcanized by irradiation and sulfur are shown in Table 3.4. The tensile strength, elongation at break, tensile strength at 100%, and hardness of radiation vulcanizate are superior to those of sulfur vulcanizate, and the dynamic properties of both are similar.

丁苯橡胶SBR是苯乙烯和顺式-1,4丁二烯的共聚物,广泛用于轿车轮胎胎面和胎体。 它占所有合成橡胶的最大消耗份额。 顺式-1,4聚丁二烯是胎面配方中最重要的混合橡胶,由顺式-1,4丁二烯聚合而成。 顺丁橡胶BR的耐磨性也是普通橡胶中最好的。 SBR和BR可以通过辐照进行交联,当它们在真空中被照射时,两者的降解率接近于零。

对于通过辐照和硫磺硫化的橡胶对比:根据ASTM D3185(2006)测量的丁苯橡胶的机械性能(见表3.4),辐照硫化胶的拉伸强度,断裂伸长率,100%定伸应力和硬度等性能优于硫磺硫化胶,此外,两种硫化胶的动态性能相似。

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3.3.1.4.3 Ethylene-propylene diene terpolymer三元乙丙橡胶

EPDM with unsaturated bond is produced by the terpolymerization of ethylene, propylene, and a small amount of alkadiene. This is applied in tire sidewalls and can be cross-linked by irradiation. As shown in Fig.3.20, the tensile strength of EPDM increases above that level, the tensile strength decrease to a larger extent. The elongation at break decreases with the increase of absorbed dose. Radiation cross-linking leads to an increase in the rigidity, and hence an increase in the tensile strength at 100% and Shore A hardness, as shown in Fig.3.21.

含不饱和键的三元乙丙橡胶是由乙烯、丙烯和少量非共轭二烯烃的共聚物。它被应用在轮胎胎侧,并且,可在辐照后发生交联反应。如图3.20所示,当辐照剂量高于某水平时,EPDM拉伸强度下降幅度较大。断裂伸长率随吸收剂量的增加而降低。辐照交联导致刚性增加,在100%定伸长率时拉伸应力增加,邵氏硬度增加(如图3.21所示)。

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3.3.1.4.4 Butyl rubber, brominated butyle rubber, and chlorinated butyl rubber丁基橡胶、溴化丁基橡胶、氯化丁基橡胶

IIR, BIIR, and CIIR are widely used in the inner liners of tires due to their excellent pressure tightness. The main chain of IIR is isobutene. IIR is a radiation-degradable rubber, and cannot be vulcanized by irradiation. The properties of BIIR and CIIR are similar to those of IIR, BIIR and CIIR rubbers and can be vulcanized by irradiation at a quite low absorbed dose, and they are degraded by irradiation with a higher absorbed dose. The mechanical properties of CIIR can be improved markedly when it is vulcanized by irradiation at 30 k Gy with the addition of polyfunctional monomers.

丁基橡胶IIR、溴化丁基橡胶BIIR和氯化丁基橡胶CIIR因其优异的密封性而被广泛应用于轮胎内衬层。其中IIR的主链是异丁烯,丁基橡胶IIR是一种辐照可降解橡胶,不能通过辐照进行硫化。BIIR和CIIR的性能与IIR、BIIR和CIIR橡胶相似,可以在较低的吸收剂量下辐照硫化,在较高的吸收剂量下辐照降解。

注:作品源于:(1)Radiation Technology for Advanced Materials:From Basic to Modern Applications 编者:Guozhong Wu, Maolin Zhai, Mozhen Wang(2)辐射化工产业发展研究http://www.shjxfz.com/new/sh/news_show.asp?id=74,版权归作者/译者所有。若有侵权,请于我们联系,将第一时间删除相关内容。