## 1 Introduction
The use of natural latex as a binder in paint has the potential to be rapidly degraded when used for exterior coverage [19, 20]. In addition, the content of several proteins in latex can cause allergic reactions in some people [21]. Natural latex can be applied directly or indirectly as a binder for emulsion paints. However, it should be noted that direct use of natural latex is not recommended. This is because raw natural rubber latex only contains dry rubber content (DRC) ranging from 20 to 40% [22]. The use of raw natural latex as a binder for emulsion paints has many disadvantages in terms of water resistance, thermal resistance, degradation by ultraviolet (UV), bacterial fungi, thin film coating, and weak bonding power to media and substrates [8, 19, 20, 23]. In addition, the protein content contained in raw natural rubber latex can cause allergies and other health problems [21]. The modifications needed to produce high-performance natural latex include adhesive properties, water resistance, and resistance to degradation, which can be applied to various media and meet specifications as an emulsion paint binder. Modifying natural latex can be performed in various ways, including prevulcanization of natural latex, monomer grafting in latex polymer chains (grafting), cyclization, depolymerization, deproteinization, hydrogenation, chlorination, epoxidation, polymerization, with a combination of natural materials, or by using latex with other polymers to improve the characteristics of natural latex. In addition, a combination of the previously mentioned methods can be used [24]. The concentration of latex and deproteinization of natural latex became the basic procedure before further modification of natural latex. Concentration and deproteinizationof natural latex are most commonly carried out by combining creaming and centrifugation methods. The combined combination of these processes produces natural latex with a DRC of up to 60% and can reduce protein by up to 90% [25; 26; 27]. Using natural rubber latex that has been concentrated (DRC up to 60%) and depolymerized, better known as liquid natural rubber (LNR), has a relatively poor performance when applied as an emulsion paint binder. The performance of LNR as an emulsion paint binder is still unable to compete with the use of PVAc binders in terms of water resistance and paint dry time. The film's properties formed from using LNR binders tend to be flexible with weak adhesive properties. This makes the LNR not good enough to adhere to the media and bind to the substrate [8; 22; 28]. Modifying natural latex by grafting or substituting monomers in polymer chains opens up new opportunities to apply latex as a binder for emulsion paints. The splicing aims to improve the adhesive properties of natural latex and its water resistance. Styrene monomer and methyl methacrylate (MMA) implanted in the LNR improved the performance of the LNR. The use of LNR as an emulsion paint binder produces paint resistance to wet scrub and abrasion, better known as washability resistance, which produces a value of four cycles. Meanwhile, LNR grafted with a combination of styrene monomer and MMA increased the washability resistance of the emulsion paint up to 6-8 cycles at the same binder concentration of 4%. It is quite promising that LNR grafted with styrene monomer or MMA can improve LNR performance. However, the optimal combination of Styrene and MMA grafted onto LNR resulted in a binder that did not meet or could not compete with the PVAc binder. This is based on the fact that LNR grafted with a combination of styrene and MMA only produces emulsion paint with a washability resistance of 6-8 cycles. In comparison, PVAc based emulsion paint produces a washability resistance of up to 10 cycles [8]. Based on the review and evaluation of several studies, grafting of natural latex styrene and MMA is possible to improve the mechanical properties, including the adhesive and cohesive properties of the formed films [8; 29; 30].