ACS Omega
http://pubs.acs.org/journal/acsodf
Article
period of time and is thus hydrolyzed. Therefore, a retention analysis of AKD at the papermaking wet end was essential to determine how to better control the internal sizing of the fi nal paper product and how to prevent AKD hydrolysis and subsequent deposit formation. Several quantitative or qualitative methods have been proposed for use in AKD retention analysis. For instance, Dart, 16 Yano et al., 17 and Asakura et al. 18 used a gas chromatography/mass spectroscopy (GC/MS) method to investigate the AKD retention determination. Similarly, Zule and Dolenc 19 used solvent extraction and GC methods for AKD analysis. GC/MS is a good analytical tool, but it would be expensive for regular quantitative analysis in a paper mill. The use of radioactive AKD has been explored by Lindström and Söderberg 6,7,20 and Lee and Luner. 13 However, this method requires radioactively tagged AKD and is thus not applicable in the industrial context. Near-infrared (NIR) or infrared (IR) spectroscopy can be used for the qualitative analysis, but it is limited in its utility for the quantitative analysis of AKD. 21,22 Jaycock and Roberts 23 and Min and Shin 24 con fi rmed that ultraviolet/visible (UV/vis) spectroscopy could be used for the qualitative and quantitative analyses of AKD. However, a more thorough investigation is required to determine its suitability for the AKD retention analysis. Furthermore, both the optimal retention level of AKD and the factors a ff ecting the emulsion stability of AKD must be investigated to solve the above- described problems associated with AKD use in papermaking processes. Accordingly, we have investigated a UV/vis spectrometry- based method for the quantitative analysis of AKD in the papermaking process and also used this for the AKD retention analysis. Based on this method, seven major factors in the papermaking wet end were evaluated to fi nd the most practical methods to increase AKD retention and prevent the production of substandard paper products. These factors included retention aid dosage, fi xing agent dosage, AKD type, fi xing agent type, fi ller types, fi ller dosage, and pulp type. Finally, we carried out mill trials on a paper machine to determine the ability of the two most important factors that we had identi fi ed, i.e., the types of fi xing agent and AKD, to enhance AKD retention and waxy spot reduction. 2. RESULTS AND DISCUSSION 2.1. Quantitative Analysis of AKD Retention Using UV/Vis Spectrometry. The e ff ect of the reaction time between AKD and 4-dimethyl aminopyridine (DMAP) in chloroform solution was examined, while the ratio AKD/ DMAP was kept constant at 1:120. Figure 1 shows that there is a rapid reaction between AKD and DMAP at a constant 1:120 ratio of AKD/DMAP and that the reaction is complete after 90 min. Thus, 90 min was con fi rmed as the su ffi cient reaction time for AKD and DMAP. Next, varying the AKD/DMAP ratio with a constant reaction time of 120 min showed that the reaction progressed until the ratio was 120:1 (Figure 2). The next experiment showed that 10 min of extraction completed AKD extraction (Figure 3). The turbidity of AKD emulsion decreased rapidly as the extraction proceeded, indicating that the AKD emulsion was dissolved by the extraction solvent, resulting in complete solubilization within 30 min. Moreover, the data in Table 1 show that the presence of other stock components such as pulps and fi llers had no
Figure 1. Relationship between reaction time and UV/vis absorbance.
Figure 2. Relationship between DMAP/AKD ratio and UV/vis absorbance.
Figure 3. Relationship between extraction time and UV/vis absorbance.
Table 1. UV/Vis Absorbance (450 nm) of Various Extraction Conditions
additional white water component
+AKD 100 ppm +AKD 0% 1.320
Hw-BKP 0.1% BCTMP 0.1%
1.317 1.308 1.309 1.316
0.002 0.001 0.003 0.001
GCC 0.1% PCC 0.1%
11228
https://dx.doi.org/10.1021/acsomega.0c01374 ACS Omega 2020, 5, 11227 − 11234
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