加速老化后粘合剂对汽车坐垫革顶层涂饰性能的影响

Effect of binder selection on topcoat property retention after accelerated weathering

在购买新车过程中，皮革座椅的选择被视为一种不能用低价替代品代替的高端选择。为了保持优质地位．对皮革座椅的舒适性、关观性和耐久性寄予了较高的期望。陶氏化学公司开发了一种丙烯酸类顶层粘合剂。当其与传统的聚氨酯分散液（PUD）粘合剂结合使用时可以显示优良性能。然而，当前顶层涂层的座椅材料在经受一系列加速老化条件处理后不能保持其性能要求。本文对比了全成品汽车装饰用皮革在经过一系列加速老化条件（热、水解和几种氙灯老化）下性能的变化情况。对较宽范围内的PUD化学成分以及化学反应的类型进行考察，判断丙烯酸类顶层粘合剂和每一种材料混合用作标准家具革筛选配方所产生的影响。对每种加速老化条件处理前后的样品进行颜色、光泽和耐折性的评估。分析数据表明：使用石英过滤器的氙孤方法处理的样品其性能最低，且测试时间与性能成比例下降。同样地．一种类似于氙弧方法处理但借助辅助灯和过滤器等设备的处理结果表明其可导致相同的破坏，但此结果需要相当长的时间处理后才可获得。置于水解和干热条件下样品产生的变化最小。这些数据也证明可以根据不同的老化条件选择PUD粘合剂。不考虑某一特殊类别PUD粘合剂的优点和缺点，PUD-丙烯酸类粘合剂的调节效果较强。这表明当2种化学品一同用于皮革家具顶层涂饰时，在加速老化条件处理后可以产生协同效应。

Within the new car purchasing process, the selection of leather seating fs viewed as a premium upgrade over less-expensive alternative options. In keeping with this premium status, leather seating carries with it high expectations for comfort, appearance, and durability. To meet these expectations, Dow Leather Solutions has developed an acrylic topcoat binder with an exceptional balance of performance properties when combined with conventional poly- urethane dispersion （PUD） binders. When considering state of the art topcoat systems, however, a continuing unmet need involves retention of properties after seating materials are subjected to a range of accelerated weathering conditions. This paper compares the performance of fully finished automotive upholstery leathers after they are subjected to a range of accelerated weathering conditions including heat, hydrolysis, and several xenon-arc chamber conditions. A broad range of PUI） chemistries and blends of chemistry types were tested, along with an examination of the effect of blending each of these with an acrylic topcoat binder in a standardized upholstery screening formulation. In order to assess performance, measurement of color, gloss, and flexibility were conducted before and after exposure to each accelerated weathering condition. An examination of the data showed that xenon arc methods using quartz filters resulted in the lowest performance with performance dropping proportionally to the length of the test. An analogous xenon-arc method involving use of an auxiliary lantern and filters was found to result in comparable sample damage, but only after much longer exposure duration. Exposure to hydrolysis and dry heat conditions produced the fewest changes in the samples. The data made evident that certain classes of PUD binders were preferred depending on the weathering specification being considered. Regardless of the various strengths and weaknesses of a particular class of PUD, a strong moderating effect was noted in many PUD-acrylic blend systems. This indicates that the two chemistries produce a measurable synergistic effect when used together in leather upholstery topcoats subjected to accelerated weathering conditions.