# Properties of Emulsion Paint with Modified Natural Rubber Late/Polyvinyl Acetate Blend Binder
## 1 Introduction  
The current high growth rate of global natural rubber (NR) production is not commensurate with consumer needs. This causes the selling value of natural rubber latex products to fluctuate and decrease. In Indonesia, the low selling value of natural rubber products has caused many rubber plantations to turn into palm oil plantations. One of the causes of the imbalance between production and demand for natural rubber is the lack of development in using natural rubber in various ready-to-use (consumable) products. Currently, the use of natural rubber in ready-to-use products is still dominated by specific fields, especially in the safety, automotive, and piping industries [1, 2]. The natural rubber latex (NRL) processing industry is still not widely developed. NRL can be obtained from the bark layer of the _Heaven brasiliensis_ plant in the liquid phase and is milky white [3, 4]. NRL contains rubber hydrocarbon particles and non-rubber substances dispersed in the liquid phase of the serum. In general, NRL has better physical properties than synthetic latex, especially its elasticity, ease of deform, vibration damping, long service life, and ease to return to its original shape [5]. NRL's advantages allow it to be developed and utilized in various final products. One of them is as an emulsion paintbinder. Several previous researchers have investigated the use of NRL as an emulsion paint binder, such as the formulation and characteristics of emulsion paint using a mixture of NRL and PVAc binder [6]. This research shows that the mix of NRL/PVAc in emulsion paint can function well as a binder. The utilization of NRL as a final product must go through several stages to reduce the amount of soluble protein in latex. Protein is a non-rubber component that functions as a natural emulsifier layer. Proteins in processed rubber products can pose a risk of allergies in humans, bring in bacteria and reduce the quality of latex processed products [7]. In addition, the protein layer is also able to inhibit the process of chemical reactions in the NR molecule [8]. Deproteinization breaks down protein by breaking the protein chain and dissolves it in a specifically suitable solvent [9]. One of the commonly used NRL deproteination methods is incubation in a batch reactor containing high-ammonia natural rubber (HANR) latex mixed with 0.1% \(w/w\) urea as a decomposing agent, 1% \(w/w\) sodium dodecyl sulfate (SDS) as emulsifier and solvent (acetone or ethanol) 0.025% \(w/w\) as sample washing medium, at a temperature of 30 \({}^{\circ}\)C. Centrifugation is used to separate the latex cream from the soluble and solubilized proteins and other impurities. After being centrifuged three times with this method, the NRL product reduced the protein content to 0.012% \(w/w\) when a solvent was not included and fell below the detection limit when a polar solvent (such as ethanol or acetone) was added [9, 10]. NRL that is free from protein content will be easier to modify. The NRL modification aims to improve its characteristics and areas of use. Modification methods currently being developed include epoxidation, vulcanization, depolymerization, and monomer grafting. Good NRL characteristics allow the development of water-borne emulsion paint binders. The use of NRL for emulsion paint binders can be an alternative in minimizing the use of synthetic latex. A paint binder is a binding agent composed of polymer components suspended in a paint containing a solvent. Binder in paint serves to glue the paint on the surface of the painted media. Research on NRL modification as a binder for emulsion pains has been growing since 2003 [11, 12]. One of the modification methods for NRL is the depolymerization process into a liquid natural rubber (LNR) product which has a shorter polymer chain and is a liquid phase at room temperature [13, 14]. Modification of the molecular structure of the NRL can produce different properties and characteristics from the base material.