# Properties of Emulsion Paint with Modified Natural Rubber Late/Polyvinyl Acetate Blend Binder
## 3 Results and Discussion  
### Washability Resistance Properties of Emulsion Paints  
Washability is the level of resistance of emulsion paint to water. This parameter is one of the feasibility and quality parameters of emulsion paint. The greater the washability resistance, the better the quality of the emulsion paint. This study shows that the binder with a mixture of modified NRL has better washability resistance properties than NRL without modification. Figure 2 presents a graph of the effect of the ratio of the LNR/PVAc binder mixture on the washability resistance. It is seen that the higher the LNR content in the emulsion paint binder, the lower the washability resistance properties. This shows that increasing the LNR content of the emulsion paint binder mixture can reduce the adhesive power of the paint. However, NRL modified to LNR resulted in better adhesion of emulsion paint than NRL without modification. LNR has a shorter carbon chain and lower molecular weight, so it usually has a fairly strong adhesion [15]. Figure 2 also shows that the washability resistance decreased up to 87%. However, for 2% LNR/PVA binder samples containing 15% and 35% LNR, there was an increase of 12 and 9 times, respectively. This is due to the enhancement of the adhesion properties of the LNR components by shortening the polymer chains. LNR also shows good compatibility with PVAc, producing binders with higher adhesion. The sample with the lowest washability resistance was found in emulsion paint with an LNR content of 100%, without PVAc. This indicates that the adhesion property of LNR is still lower than that of PVAc. Figure 3 shows a decrease in the washability resistance properties and the increase in the NRL-g-(MMA-co-St) levels in the emulsion paint binder. This means that the adhesion properties of NRL-g-(MMA-co-St) are still lower than those of PVAc. However, NRL-g-(MMA-co-St) had better adhesion properties than either unmodified NRL or LNR. The washability resistance of LNR is much lower than that of NRL-g-(MMA-co-St) at the same composition of binder mixture and binder content of emulsion paint. This is because NRL-g-(MMA-co-St) has a better affinity between particles and water resistance than LNR [16]. The low adhesion property of NRL-g-(MMA-co-St) compared to PVAc is because NRL-g-(MMA-co-St), which coats emulsion paints, oxidizes faster than PVAc. The oxidation process in the emulsion paint layer will not stop until the binder layer dries [17]. A suitable emulsion paint binder must also pay attention to the material's oxidation ability, chemical resistance, and mechanical properties [18]. Emulsion paint with a binder NRL-g-(MMA-co-St) has resistance to more extreme temperatures. This is due to grafted styrene and MMA monomers in the rubber polymer chain. Styrene and MMA monomers bonded to rubber components can increase the rubber latex's elasticity, tensile strength, and durability [16]. Figure 3: Washability resistance of emulsion paints with NRL-g-(MMA-co-St)/PVAc binder mixture. Figure 2: Washability resistance of emulsion paints with LNR/PVAc mixed binder. The washability resistance of emulsion paint decreases with increasing NRL-g-(MMA-co-St) levels in the binder, up to 40%. Sample A15 showed the best properties, namely the ratio of NRL to the monomer of 80:20 and the ratio of the mixture of NRL-g-(MMA-co-St)/PVAc of 15:85. This shows that the more MMA and St bonded to the NRL, will decrease the elasticity and adhesion of the NRL. Materials mixed with NRL-g-(MMA-co-St) at the suitable composition will lower the surface tension, thereby increasing the adhesion properties of the mixture [16]. Figure 4 shows the tendency of washability resistance properties from the influence of the LNR-g-(MMA-co-St)/PVAc ratio. Increasing LNR-g-(MMA-co-St) levels in PVAc showed a decrease in washability resistance. This shows that LNR-g-(MMA-co-St) does not perform better than NRL-g-(MMA-co-St) as an emulsion paint binder.