碳氫化合物對含有二氧化矽填料之丁苯-天然共混橡膠性能之影響

自工業革命以來，人類生活大幅進步，卻也對自然環境造成極大的傷害，隨著近年來環保意識的抬頭，促使輪胎工業投入了大量資源在開發綠色(省油)輪胎。輪胎的性能常以所謂的魔術三角來評價，包括輪胎的滾動阻力(rolling resistance)、濕地抓地力(wet traction)及使用磨耗(wear)，然而這三種性能指標就如蹺蹺板一般，通常改善其中一項就會使其他變差，而綠能輪胎的指標是降低滾阻且不犧牲其他二者，這樣的進步主要是在胎面膠料中混摻二氧化矽奈米顆粒而達成。為了進一步改善綠色輪胎的性能，尤其是抓地力及省油性上，本研究探討在混摻了二氧化矽的胎面膠料中再添加碳氫化合物樹脂對其動態性質之影響。首先，我們測定三種碳氫化合物樹脂(由美商艾克森美孚提供)的溶解度參數，以了解這些碳氫化合物樹脂與胎面膠料中各種橡膠的親和性。接著，我們使用液相混合製程和固相混摻製程來驗證樹脂與不同橡膠的互溶程度。從液相混合製程中我們發現這三種樹脂只能夠和丁苯橡膠混溶，並且我們也從固相混摻製程中確認樹脂能混溶於天然橡膠及丁苯橡膠(25:75)的混摻系統中。由示差掃描量熱法及動態機械分析的結果，我們推測碳氫化合物樹脂對天然橡膠及丁苯橡膠(25:75)混摻系統的動態性質影響可分為兩種機制:其一是樹脂能提高系統的玻璃轉化溫度，進而提升輪胎的濕地抓地力，但也會增加滾動阻力。其二是我們從潘恩效應的實驗中發現碳氫化合物樹脂能有效的提升填料的分散性，進而增加濕地抓地力且減少滾動阻力。此二種機制對輪胎的濕地抓地力都有正向的貢獻，但對滾動阻力則有相反的影響。根據混摻有二氧化矽的胎面膠料的實驗結果，我們發現添加10phr以下的樹脂可以大幅提升濕抓力(30-40%)，但會使滾阻小幅增加(0-10%)，但若添加更多樹脂，則會使得滾阻大幅提升，對省油的要求有不利的影響。

關鍵字

綠能輪胎；天然橡膠；丁苯橡膠；碳氫化合物樹脂

並列摘要

Since the industrial revolution, human life has enjoyed great progress, but it has also caused great harm to the natural environment. With the rise of environmental awareness in recent years, the tire industry has invested a lot of resources in developing green (fuel-efficient) tires. The performance of tires is often characterized by the so-called magic triangle, including the rolling resistance, the wet traction and the wear. However, these three performance indicators are very difficult to improve at the same time. Improving one will usually make the other worse. However, the goal of green tire is to reduce the rolling resistance without sacrificing the other two. This magic progress is mainly achieved by mixing the silica nanoparticles into the tread compound. In order to further improve the performance of green tires, especially the grip and fuel economy, this study investigated the effect of the addition of hydrocarbon resin on the dynamic properties of the tread compound. First, we determined the solubility parameters of three hydrocarbon resins (supplied by ExxonMobil) to understand the affinity of these hydrocarbon resins with various rubbers in the tread compound. Next, we used a liquid phase mixing process and a solid phase mixing process to verify the miscibility of the resins with different rubbers. From the liquid phase mixing process, we found that these three resins can only be miscible with styrene-butadiene rubber, and we also confirmed from the solid phase mixing process that the resins are miscible with natural rubber and styrene-butadiene rubber (25:75). From the results of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), we speculate that the influence of hydrocarbon resins on the dynamic properties of natural rubber and styrene-butadiene rubber blending system can be attributed into two mechanisms. First, addition of the resins increase the system's glass transition temperature, which in turn improves the wet grip of the tire. However, this mechanism also increases rolling resistance of the compound. The second is that the hydrocarbon resin can improve the dispersibility of the fillers, thereby increasing the wet grip and reducing the rolling resistance. This argument is supported by the measurement of the Payne effect. These two mechanisms have positive contribution to the wet grip of the tire, but have opposite effects on the rolling resistance. According to the experimental results of the silica-filled tread compound, we found that adding 10 phr of resin can greatly improve the wet grip (30-40%), but will increase the rolling resistance slightly (0-10%). However, if more resin is added, the rolling resistance will be greatly increased, which will adversely affect the fuel saving requirements.