Vinyl Acetate Monomer

Polyvinyl acetate emulsion (PVAc), commonly known as white latex, are widely used as a key polymer adhesive due to their ability to be directly modified with a variety of additives, excellent mechanical strength, and resistance to adhesive defects. Furthermore, their environmental friendliness as a water-based adhesive makes them particularly attractive. However, due to different synthesis processes, white latexes also have some drawbacks, such as limited water and heat resistance, generally high viscosity, and high solids content, which increase their cost.   1. Effect of Polyvinyl Alcohol on Emulsion Viscosity Experiments were conducted using fully alcoholyzed PVA1799 and partially alcoholyzed PVA1788. The viscosity of the emulsion prepared with PVA1788 was 3.8 Pa·s, while that of the emulsion prepared with PVA1799 was 3.0 Pa·s. This is primarily due to the grafting effect of the tertiary hydrogen atoms -CH(OCOCH3)- in PVA1788. In addition, different polyvinyl alcohol production methods result in different distributions of residual acetate groups within the molecule, resulting in different viscosities in the resulting polyvinyl acetate emulsions. PVA1788 was selected for this experiment.   2. Effect of Initiator on Emulsion Viscosity and Solids Content Generally, at a specific temperature for polymerization, if you start with very little initiator, both viscosity and solids increase as you add more initiator. The viscosity peaks at 4.2 Pa·s when the initiator is 0.6% of the total monomer, resulting in a 36% solids content. If you keep adding initiator past that point, the emulsion gets less viscous, but the solids stay about the same. During emulsion polymerization, the pH of the medium directly affects the decomposition rate of the initiator. The pH of the emulsion polymerization system is required to be around 6. Due to the presence of a small amount of Acetic Acid Vinyl Ester Monomer and the sulfate groups generated during initiator decomposition, the pH of the system drops to 4-5. Therefore, an appropriate amount of sodium bicarbonate is used to adjust the pH.   3. Effect of Emulsifier Amount on Emulsion Viscosity With other conditions unchanged, the emulsifier dosage was varied. The results are shown in Figure 1. Too little emulsifier results in poor emulsion stability and easy demulsification. Emulsion viscosity increases with increasing emulsifier dosage, reaching its maximum viscosity at 0.15% of the total monomer content. When the emulsifier dosage exceeds the optimal value, the emulsion particles increase in number, their size decreases, and the viscosity decreases.   4. Effect of Reaction Temperature on Emulsion Viscosity and Solids Content Experiments show that when you keep the reactant ratios, addition method, and stirring the same, changing the reaction temperature really does change how thick the polyvinyl acetate emulsion is and how much solid stuff is in it. The results are shown in Table 2. This is because polymerization is endothermic, so higher reaction temperatures favor the reaction. However, when the reaction temperature reaches 80°C, exceeding the boiling point of vinyl acetate monomer (72°C), it increases reflux and consumes energy. Low temperatures also slow the reaction, leading to incomplete reaction and low emulsion viscosity.   5. Effect of Monomer Purity on Emulsion Viscosity and Solids Content Due to storage and transportation requirements, polymerization inhibitors are often added to vinyl acetate before shipment to maintain its stability. To facilitate polymerization, the vinyl acetate was distilled before the experiment. The results are shown in Table 3. Table 3 shows that the properties of vinyl acetate directly affect the emulsion viscosity and solids content. Distillation of the monomer significantly increases the viscosity of the polyvinyl acetate.   6. Conclusions The traits of Vinyl Acetate Monomer (VAM) and polyvinyl alcohol change how thick the emulsion is and how much solid stuff is in it. The viscosity and solid content of an emulsion are affected by the reaction temperature, the amount of reactants, and how you add monomers, emulsifiers, and initiators during the emulsification procedure. We got a milky white polyvinyl acetate emulsion with some great qualities. It has a viscosity of 5.8 Pa•s, a solid content of 42%, a pH between 6 and 8, and a blue tint. The best part is, we achieved this by keeping the reaction temperature at 75 ℃ and carefully adding the emulsifier (0.15%) and initiator (0.6%) drop by drop in batches, based on the total monomer amount.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

Vinyl acetate is a colorless flammable liquid with a strong odor. Its vapor is irritating to the eyes. It is insoluble in water but soluble in most organic solvents. Vinyl acetate monomer(VAM) is flammable and reacts rapidly with chlorine, bromine, and ozone. There are two production process routes for vinyl acetate monomer: the ethylene method and the acetylene method. The acetylene method can be divided into a liquid phase method and a gas phase method, and the ethylene method can also be divided into a liquid phase method and a gas phase method.   Acetylene gas phase method: desulfurized and dephosphinated calcium carbide acetylene and acetic acid are used as raw materials, the catalyst is zinc acetate-activated carbon (15:100), and a promoter is added. The reaction temperature is 170~200℃, the pressure is atmospheric pressure, and the space velocity is 200~400/h. Reaction results: acetic acid single-pass conversion rate is 25~40%, acetylene single-pass conversion rate is 12~16%. The selectivity of VAM is 92~96% for acetylene and 95~98% for acetic acid. The total yield of VAM is 97~98% for acetic acid and 92~96% for acetylene.   The catalysts for the ethylene gas phase process are mainly Pd-Au, Pd-Pt and Pd-Cd supported catalysts, and the carriers are mainly silica gel and alumina. The two main factors affecting the catalyst are the coordination ability of Pd and the ability of acetic acid or acetate to oxidize Pd(0) to Pd(II). The single-pass conversion rate of ethylene in this process is 8~10%, the single-pass conversion rate of acetic acid is 8~20%, and the VAM ( CW 40-600 & ECO VAE 1608) selectivity based on ethylene is 90~94%.   In the past few years, the acetylene process has been gradually replaced by the ethylene process due to the high cost of raw materials. However, with the continuous rise in oil prices, the acetylene process has regained economic vitality, especially the acetylene process using natural gas as raw material. At present, the acetylene process still occupies an important position in China. The ethylene gas phase process occupies a dominant position in the market due to its good processability and economic performance. At present, the ethylene production technology in China accounts for more than 55% of the total national production capacity.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

VAM stands for Vinyl Acetate Monomer. It is a key raw material used in the production of various polymers and copolymers. Vinyl acetate monomer is a clear liquid with a distinct odor. It is primarily derived from the reaction between acetylene and acetic acid.   VAM is widely used in the manufacturing of polyvinyl acetate emulsions, which find applications in adhesives, paints, coatings, and textiles. The copolymerization of VAM with other monomers, such as ethylene, creates ethylene-vinyl acetate (EVA) copolymers, which have excellent flexibility, adhesion properties, and low-temperature resistance. EVA is extensively used in various industries, including footwear, packaging, wire and cable insulation, and solar cell encapsulation, among others.   The versatility of VAM as a building block for different polymers and copolymers makes it a crucial material in the chemical industry. Its unique properties, such as good adhesion, film-forming capability, and chemical resistance, contribute to the wide range of applications it offers.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA,PVA 098-08 & PVA 1099) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.