Synthesis and performance impact of membrane-assisted PUD (2)

visible from Figure 1, the MFT of the compound lotion decreases with the decrease of n (-NCO)/n (-OH). When n(-NCO)/n(-OH) is reduced from 1.9 to 1.3, the MFT of the compound emulsion is reduced from 35.8 to 30.9 degrees C, which helps to improve the film-forming capacity. This is because with the increase of n (-NCO)/n(-OH), the residual - NCO-based content of polyurethane pre-polymer increased, the molecular chain of the arbond bond unit increased, rigid arbond bond structure increased is not conducive to the molecular chain of free diffusion movement and latex particle deformation, so the film-assisted decline. In addition, PUD particle size with n (-NCO)/n (-OH) decreased, small particle size PUD is easier to fill in the high Tg particle gap, is conducive to the improvement of membrane capacity, and when n (-NCO)/n (-OH) is too low, pre-adhesive viscosity is not conducive to PUD preparation, therefore, n (-NCO)/n (-OH) selection 1.3 is appropriate.2.1.2 The effect of soft/hard segment mass ratio on the performance of the film aidfixed n (-NCO)/n (-OH) s 1.3, w (DMPA) s 5%, according to the method described in 1.2 synthesis solid content is about 38 % PUD;To explore the law of the effect of soft/hard segment ratio on PUD film-assisted film performance, the corresponding MFT is shown in Figure 2 at solid segment m (PUD)/m (PA0) and 15/85 complex.by table 3, with the increase of the soft segment ratio, PUD appearance gradually become transparent, the average particle size gradually decreased, viscosity increased trend. This is due to the increase of the ratio of soft and hard segments, the content of NCO in the pre-cluster decreases, the cross-linking structure of the arbond bond generated by the reaction with water or ethyl diamine in the dispersion stage decreases, and the hydrogen bond action decreases, which is conducive to emulsification dispersion. In addition, with the increase in the content of the soft segment, the molecular chain segment becomes softer, easily cut into smaller particles under the high shearing effect, so the particle size gradually becomes smaller and the appearance becomes better. However, the smaller the particle size, the greater the number of particles, the more particles than the surface area, correspondingly, the surface of the particle hydration layer volume increased, and thus the viscosity increased.visible from Table 4, PUD film-assisted film capacity is enhanced with the increase of the ratio of soft and hard segments.combined with Figure 2 analysis, with the increase of soft/hard segment mass ratio, the MFT of compound emulsion showed a decreasing trend. When the soft/hard segment mass ratio is increased from 45/55 to 55/45, the MFT of the compound emulsion is reduced from 32.5 to 29.9 degrees C, which helps to improve the film-forming capacity. This is because with the increase of the proportion of soft and hard segment polyurethane molecular chain polyether chain content, polyether molecular chain softness is better, is conducive to the free diffusion movement of the chain segment and latex particle deformation fusion, so help membrane performance to improve.Second, the PA main chain is composed of C-C single bond, the molecular chain polarity is small, and the polarity of the polyether molecular chain is relatively small, according to the principle of "similar compatibness", the increase of the soft segment ratio is conducive to improving the compatible between PUD and PA0, and thus improve the performance of PUD's assisted membrane; However, when the proportion of soft segments is too high, the preparation of the film n-PUD on the hardness of the compound coating film decreased significantly. Therefore, the soft/hard segment quality ratio of 55/45 is appropriate.
2.1.3 DMPA addition on the effect of film-assisted performance on the . Fixed n (-NCO)/n (-OH) =1.3, soft/hard segment=55/45, synthesis of PUD with a solid content of approximately 38% according to the method described in 1.2; The effect of quantity on puD-assisted film performance is measured at different soft/hard segment ratios, as shown in Figure 3 of MFT corresponding to solid proportion m (PUD)/m (PA0) and 15/85 re-matching.by Table 5, with the increase of DMPA content, PUD appearance gradually become transparent, the average particle size gradually decreased, viscosity showed an increasing trend. This is due to the increase in DMPA content, the more hydroffin on the molecular chain segment, the stronger the affinity to water, conducive to emulsification dispersion, in addition, with the DMPA content increased, under the high shearing effect is easy to be cut into smaller particles, so the particle size gradually become smaller, better appearance. However, the smaller the particle size, the greater the number of particles, the more particles than the surface area, correspondingly, the surface of the particle hydration layer volume increased, and thus the viscosity increased.. As can be known from Table 6, with the increase of DMPA content, puD film-aiding effect is more significant.
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