Developing Evaluation Methods of Indoor Air Quality for Information Processing Devices in Information Working Environments

最近，污染物（VOC、颗粒、臭氧等）在室内环境中，从各种打印机发出的辐射已经成为一个严重的问题。本研究将商品化的喷墨打印机（IP）、单色激光打印机（MLP）和彩色激光打印机（CLP）分别安装在由两个洁净室组成的测试室内，对它们的颗粒排放进行了表征，并提出了有效的对策。测量了其发射率、发射粒子的粒径分布和荷电特性。此外，通过将它们引入扩散干燥器中，然后比较其上游和下游的尺寸分布来检查它们的稳定性。结果，在打印模式下，IP的颗粒排放率为每张纸10^6个颗粒，而MKP和CLP的颗粒排放率为每张纸10^7个颗粒。这些颗粒主要小于100nm，表明它们不是直接来自调色剂和主墨雾。此外，稳定性测试显示，在打印模式下发射的颗粒由非挥发性残留物和水组成。也就是说，从IP中夹带被指定为“卫星”并且比主墨雾更细的墨雾，以产生尺寸为约30 nm的固体染料颗粒。对于MLP和CLP，通过在定影步骤中加热覆盖有调色剂的纸张，水和苯乙烯蒸汽从纸张中散发出来，然后成核成纳米颗粒（尺寸约35 nm）。所形成的颗粒逐渐收缩为可能主要由苯乙烯聚合物组成的稳定残余物。因此，这些研究结果证实，不仅要采取针对纳米颗粒排放的对策，而且要进行监管。

Recently, contaminants (VOCs, particles, ozone, etc.) emitted from various printers have become a serious issue in indoor environments. In this study, the particle emission from them was mainly characterized to obtain the effective countenneasures against it. A commercialized ink-jet printer (IP), monochrome laser one (MLP) or color laser one (CLP) was installed in a test chamber composed of dual clean booths. The emission rate, size distribution and charge one of particles emitted from it were measured. Further, their stability was checked by introducing them into a diffusion dryer followed by the comparison of their size distributions upstream and downstream of it. As a result, the particle emission rate from IP was in the order of 10^6 particles per sheet at the printing mode, while that from MKP and CLP was in the order of 10^7 at both printing and paper feed modes. These particles were dominanily less than 100nm, indicating that they were not directly derived from toner and main ink mists. Further, the stability tests revealed that the particles emitted at the printing mode are composed of nonvolatile residues and water. That is, ink mists, which are designated as "satellite" and finer than main ones, are entrained from the IP to result in solid dye particles of about 30 nm in size. For MLP and CLP, water and stryrene vapor are emitted from paper sheets covered with toner by heating them at the fixation step, and then are nucleated into nano-particlcs (about 35 nm in size). The formed particles gradually shrink to be stable residues that might be mainly composed of styrene polymer. Therefore, these findings confirmed that not only the countermeasures against the nano-particle emission but its regulation should be undertaken.