Synthesis and performance impact of membrane-assisted PUD (3)

combined with Figure 3 analysis, with the increase of DMPA content, the MFT of compound lotion showed a decreasing trend. When the DMPA content is increased from 4% to 8%, the MFT of the compound lotion is reduced from 31.2 to 29.0 degrees C, which helps to improve the film-forming capacity. However, when the amount of DMPA added greater than 5% on the film-aid effect is not obvious, the film resistance may have adverse effects, so 5% is appropriate.
2.1.4 Effect of film-assisted PUD addition on MFT
Preferably formula parameters are: n (-NCO)/n (-OH) =1.3, m (soft segment)/m (hard segment) 55/45, synthetic PUD and PA0 are re-matched in proportion to different solids, MFT data of compound emulsion are tested, and the effect law of the addition of assisted film PUD on the compound emulsion MFT is examined, and the test results are shown in Figure 4.. As can be seen from Figure 4, the amount of added helper film PUD has a significant effect on the compound emulsion MFT. When the PUD/PA0 mass ratio is increased from 0/100 to 25/75, the MFT of the compound emulsion is reduced from 66 to 4.5 degrees C, which can form a continuous transparent coating film under the condition of 5 degrees C, and when the puD dosing continues to increase, the decline of the compound lotion MFT tends to be flat.This is because when the PUD addition is less, the high MFT PA0 in the compound lotion dominates, at this time PA0 is continuous phase, the film-forming PUD is the dispersion phase, the film temperature is higher, when the PUD addition gradually close to 25%, The compounding system has turned in reverse, PA0 is distributed in the continuous phase formed by the soft resin PUD, and then melts to form a continuous transparent coating film, when the amount of puD continues to increase, the MFT of the compound lotion gradually close to the MFT value of puD, so the downward trend slows down.2.2 Performance TestThe film-assisted film PUD and PA0, synthesized with the parameters of the polymer emulsion of the preferred formula, were combined with PA0 by solid ratio of 25/75 to determine its coating performance and compared with the coating performance of the pure PA0 emulsion after it was added as a membrane additive, the results of which are listed in Table 7.. Table 7 shows that the film-aid PUD prepared in this paper can replace the film-forming additive-assisted PA0 film, can greatly reduce the VOC of water-based coating, although slightly reduce the hardness and water resistance of the coating film, but the compound emulsion coating film can still meet the requirements of water-based wood coating, the total volatile organic compound content (TVOC) in the product is less than 30 g/L. To meet the technical standards of HJ 2537-2014 for environmental marking products promulgated and implemented by the State in July 2014, the volatile organic compound (VOC) content of water-based wood coatings is required to be 80 g/L.3 ConclusionUsing the pre-meso-synthetic PUD, the effect law of soft segment/hard segment ratio, n(-NCO)/n(-OH), DMPA content on the compounding system MFT was studied, and then the effect law of the added amount of assisted membrane PUD on the compounding system MFT was studied, and the effect law of the compounding system MFT was studied, and the effect law of the soft segment/hard segment was obtained: when the soft segment/hard segment was 55/45, n (-NCO)/n (-OH) , w (DMPA) - 5% of the conditions prepared by the film-assisted PUD, according to the solid percentage m (PUD)/m (PA0) - 25/75 prepared water-based wood coating can be prepared without film additives at 5 degrees C to form a continuous transparent coating film, compared with the PA0 preparation of the coating, the system VOC content reduced to 30g/L, successfully prepared excellent performance of ultra-low VOC water-based wood coating..