Interview: "Some challenges remain"
从溶剂型涂料过渡到水性涂料-仍然存在一些挑战
Interview by Damir Gagro
Although water-borne epoxy performance has advanced significantly over the past 40 years, there are some challenges that remain when transitioning from solvent- to water-borne coatings, says Daniel J. Weinmann, market development manager at Westlake Epoxy.
Westlake环氧树脂公司市场开发经理Daniel J. Weinmann表示,尽管水性环氧树脂的性能在过去40年里有了显著的进步,但从溶剂型涂料过渡到水性涂料仍然存在一些挑战.
What are the remaining challenges in the transition from solvent- to waterborne coatings?
从溶剂型涂料过渡到水性涂料还存在哪些挑战?
Daniel J. Weinmann: Over the past few decades, waterborne epoxy coatings have significantly improved their capability to deliver epoxy performance in real world applications. For commercial coating formulations, the solvent content in waterborne epoxy coatings has dropped from 150 g/L VOC to less than 50 g/L VOC: in some cases, even approaching zero VOC levels. Even at ultra-low solvent content, these waterborne epoxy formulations provide superior adhesion, higher chemical resistance, and excellent corrosion resistance. Although waterborne epoxy performance has advanced significantly over the past 40 years, there are some challenges that remain when transitioning from solvent- to waterborne coatings. These challenges fall into two primary categories: formulation development and application properties.
Daniel J. Weinmann:在过去的几十年里,水性环氧涂料在实际应用中显著提高了环氧性能.商业涂料配方里,水性环氧涂料中的溶剂含量已从150 g/L VOC下降到50 g/L VOC以下:在某些情况下,甚至接近零VOC水平.
即使在超低溶剂含量,这些水性环氧树脂配方提供优越的附着力,更高的耐化学性和优异的耐腐蚀性.尽管水性环氧树脂的性能在过去的40年里有了显著的进步,但从溶剂型涂料过渡到水性涂料仍然存在一些挑战.这些挑战主要分为两类:配方研发和应用特性.
In formulation development, the main challenges are robustness, cost and component stability. Waterborne epoxy coatings typically require multiple additives to overcome specific hurdles related to the presence of water as the carrier; specifically, high interfacial tension (requires wetting and dispersing agents, flow and levelling agents) and the potential for accelerated corrosion (flash rust inhibitors). The choice of additives and their use level is critical to develop a coating formulation that has acceptable component stability, good application properties and superior film performance. Optimizing the additives in these formulations may increase the time (and costs) needed for coatings development.
在配方开发中,主要的挑战是稳健性、成本和成分稳定性.
水性环氧涂料通常需要多种添加剂来克服与水作为载体存在相关的特定障碍;具体来说,高界面张力(需要润湿和分散剂,流动和平整剂)和加速腐蚀的潜力(闪速防锈剂).添加剂的选择及其使用水平对于开发具有可接受的成分稳定性、良好的应用性能和优越的薄膜性能的涂料配方至关重要.优化这些配方中的添加剂可能会增加涂料开发所需的时间(和成本).
Regarding application properties, waterborne epoxy coatings are challenged when the end-use requires application at lower temperatures and higher relative humidity. Under these conditions, the reactivity and drying of the two-part epoxy/amine system slow down significantly, and the high relative humidity makes it more difficult for the water to evaporate from the coatings film. Some ways to address this issue are to use heaters to warm the substrate or to use warm air flow to drive the release of water from the coating film.
在应用性能方面,当最终使用要求在较低的温度和较高的相对湿度下应用时,水性环氧涂料受到了挑战.在此条件下,双组分环氧/胺体系的反应性和干燥速度明显减缓,较高的相对湿度使得水分更难从涂层中蒸发.解决这个问题的一些方法是使用加热器来加热底材或使用暖空气流动来驱动涂层膜中的水的释放.
Are there any developments that could expand the areas of application of water-based coatings?
有什么发展可以扩大水性涂料的应用领域吗?
Weinmann: To protect the environment, improve worker safety and provide longer service life, coatings manufacturers are developing waterborne epoxy systems that deliver higher performance, faster return to service and superior film formation without any added co-solvents. With ultra-low VOC epoxy systems, formulators can take their waterborne epoxy coatings all the way towards zero solvent emissions. Another development area is to explore ways to reduce the cost of waterborne epoxy coatings. These options include formulating acrylic/epoxy hybrid coatings for institutional applications; as well as, selecting waterborne amine hardeners that offer lower use levels. For example, “Epikure Curing Agent 8530-W-75” has a use level of only 24 PHR (parts per hundred weight resin).
Weinmann:为了保护环境,提高工人的安全,并提供更长的使用寿命,涂料制造商正在开发水性环氧树脂系统,提供更高的性能, 无需添加任何辅助溶剂的更快的恢复服务和优越的成膜.采用超低VOC环氧体系,配方商可以将水性环氧涂料一直推向零溶剂排放.
另一个发展领域是探索降低水性环氧涂料成本的方法.比如选择配制丙烯酸/环氧混合涂料;以及,选择用量较低的水性胺固化剂.例如,“Epikure 8530-W-75”的用量重量比为24 PHR(树脂重量比).
Another option to reduce cost is to select a more economical epoxy dispersion, or a liquid epoxy resin emulsion. When choosing to reduce cost, the resultant performance may be somewhat reduced. However, for light duty or medium duty applications, these lower cost options can still meet the minimum performance requirements depending on the service environment.
降低成本的另一种选择是选择更经济的环氧分散体,或液体环氧树脂乳液.当选择降低成本时,所产生的性能可能会有所降低.然而,对于轻负荷或中等负荷的应用.取决于服务环境.这些经济型选项仍然可以满足最低性能要求,
What is R&D in water-based coatings currently focusing on?
目前水性涂料的研发重点是什么?
Weinmann: Our goal is to help the coatings industry make a successful transition to solvent-free, waterborne coatings; and by working together, we can achieve this vision with our customers. The developments mentioned above are fully commercial so now, our R&D groups are focused on developing waterborne epoxy coatings for more challenging applications. The global R&D labs are working to improve lower temperature cure, to increase product stability and to develop new waterborne epoxy dispersions and amine hardeners that are easier to formulate, as well as, to improve adhesion to ultra-smooth steel, wood, and other difficult substrates. For improved performance, there are initiatives to develop very high corrosion resistance and higher chemical resistance, waterborne epoxy systems.
Weinmann:我们的目标是帮助涂料行业成功过渡到无溶剂、水性涂料;通过共同努力,我们可以与客户实现这一愿景.上述研发已经完全商业化,所以现在,我们的研发团队专注于开发水性环氧涂料,以应对更具挑战性的应用.
全球研发实验室正致力于改善低温固化,提高产品稳定性,开发更容易配制的新型水性环氧分散体和胺硬化剂,以及提高对超光滑钢材、木材和其他难处理底材的附着力.为了提高性能,有开发非常高的耐腐蚀性和更高的耐化学性,水性环氧树脂系统的举措.
More information about expoxy resins are included in our refenrce book "Epoxy resins" in the European Coatings Webshop
关于环氧树脂的更多信息可参考欧洲涂料协会出版的’环氧树脂”一书
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