01 Polyurethane The structure of polyurethane is formed by the reaction of polyisocyanates (e.g., diisocyanate OCN-R-NCO) and polyols (e.g., diol HO-R-OH), where urethane segments are repeating structural units. Polyurethane structures have structures similar to amide and ester groups; therefore, the chemical and physical properties of polyurethane are between those of polyamides and polyesters. Synthesis of Waterborne Polyurethane Waterborne polyurethane (WPU) is a binary colloidal system using water as a medium, including aqueous solutions, aqueous dispersions, and aqueous emulsions. Polyurethane particles are dispersed in a continuous aqueous phase, also known as waterborne PU or water-based PU. It has advantages such as being non-toxic, non-flammable, environmentally friendly, energy-saving, safe and reliable, not easily damaging the coated surface, and easy to operate and modify. Classification of Waterborne Polyurethanes Based on appearance, waterborne polyurethanes can be classified into polyurethane aqueous solutions (particle size <1nm), polyurethane dispersions (particle size 1nm～100nm), and polyurethane emulsions (particle size >100nm). Based on the charge properties of the hydrophilic groups, waterborne polyurethanes can be classified into anionic, cationic, and nonionic waterborne polyurethanes. Based on the synthetic monomers, waterborne polyurethanes can be classified into polyether-type, polyester-type, and polyether/polyester hybrid types. Based on product packaging, waterborne polyurethanes can be classified into single-component and two-component waterborne polyurethanes. 02 Raw Materials for the Synthesis of Waterborne Polyurethanes Polyisocyanates Polyisocyanates used in the synthesis of waterborne polyurethanes include two main categories: aromatic and aliphatic. Aromatic polyols mainly include TDI (toluene diisocyanate) and MDI (diphenylmethane diisocyanate); aliphatic polyols mainly include HDI (hexamethylene diisocyanate) and IPDI (isophorone diisocyanate). Oligomer polyols used in the synthesis of waterborne polyurethanes mainly include two categories: polyether type and polyester type. They constitute the soft segment of polyurethane. Chain extenders are commonly used in the synthesis of waterborne polyurethanes to adjust the molecular weight and the ratio of soft to hard segments. Chain extenders are mainly polyfunctional alcohols or amine compounds. Hydrophilic agents (hydrophilic chain extenders) are chain extenders that can introduce hydrophilic groups onto the main chain of waterborne polyurethane macromolecules. They are functional monomers used in the preparation of waterborne polyurethanes. These chain extenders contain carboxyl groups, sulfonic acid groups, or tertiary amine groups. Polyurethanes with these groups become water-soluble after neutralization and ionization. Neutralizing Agent (Salt-forming Agent) A neutralizing agent is a reagent that can form salts with carboxyl, sulfonic acid, or tert...

Acrylic resins are an indispensable and commonly used resin in water-based coatings. They are widely used in metal coatings, ABS and PC coatings, and glass coatings requiring hardness, especially solid acrylic resins. There are many types of solid acrylic resins. Some solid acrylic resins can be used to produce water-based paints, including the currently popular UV-cured coatings and high-solids coatings. With increasing environmental awareness, water-based coatings are bound to become the mainstream. Advantages of solid acrylic resins: Low storage and transportation costs, good safety. Most solid acrylic resins use methacrylates as the main monomer, and their weather resistance and chemical resistance are superior to acrylic monomers and styrene. They have good potential for promotion in exterior architectural coatings, containers, and automotive refinish paints. Because certain types of solid acrylic resins can be used as water-based UV-cured paints and high-solids coatings, adjusting the monomers can produce low-pollution and low-odor acrylic exterior architectural coatings. Solid acrylic resins contribute to the development of low-pollution coatings in the coating industry. Domestically produced solid acrylic resins are now in mass production, achieving similar performance to imported resins in certain aspects, such as dissolution speed and weather resistance, thus making a new contribution to the promotion of acrylic paints. Organosilicon-modified acrylic resins In addition, organosilicon-modified acrylic resins are also at the forefront of development, as they can be used in the automotive industry for elastic topcoats and interior and exterior wall paints. Organosilicon-modified acrylic coatings are high-performance coatings created by introducing organosilicon polymers into the acrylate structure through a reaction. Silyl chloride-acrylic resin coatings have good performance and excellent adhesion to non-ferrous metals and various plastics. Therefore, its applications are constantly being developed. To meet the latest requirements, users urgently need to develop single-component resin products with good coating application properties and the same performance as two-component products. Sinograce Chemicalhas served water-based coating customers for over 15 years, possessing experience in producing corresponding acrylic resin products to meet the needs of different substrates. For more product information and technical guidance, please contact us.

Sometimes, a slight ammonia smell is detected in water-based acrylic emulsions, which confuses many people: is this normal or is there a problem? First, we need to clarify that acrylic emulsions themselves do not produce an ammonia smell. However, during their production, ammonia-containing additives may be added to adjust their performance or improve their stability. These additives gradually volatilize during use, producing a slight ammonia smell. Therefore, under normal use, a slight ammonia smell in acrylic emulsions is normal. Waterborne acrylic resins are used in emulsion form in textile finishing agents, adhesives, varnishes and other related products. Follow us to learn more about chemical engineering.

I. Why Must Cigarette Packaging Printing Shift to Water-Based Acrylic Emulsions? Traditional solvent-based inks contain large amounts of volatile organic compounds (VOCs) such as benzene and ketones, which not only harm the health of operators but also easily leave residues on packaging, affecting tobacco safety. Water-based acrylic emulsions, using water as the dispersion medium, have extremely low or even zero VOC content, are non-toxic, odorless, and non-flammable, meeting industry standards such as the "VOC Limits in Tobacco Products and Materials," making them the preferred material for current green printing certification. Furthermore, modern cigarette packaging pursues high gloss, metallic feel, and vibrant colors. Through molecular structure design, water-based acrylic emulsions can achieve printing performance comparable to or even superior to solvent-based inks. II. Key Performance Requirements and Technical Adaptation Cigarette packaging printing mostly employs gravure or flexographic high-speed overprinting processes, placing stringent requirements on the ink's workability, stability, and film-forming properties. Water-based acrylic emulsions must meet the following core indicators: Excellent color development and high gloss The emulsion must possess good pigment wetting and dispersion capabilities to ensure color saturation and accurate reproduction. Some specialized emulsions can achieve a gloss level of over 80 at a 60° angle, giving cigarette packs a luxurious feel. Rapid drying and good leveling properties Under medium-to-high speed printing conditions (80–150 m/min), rapid moisture evaporation and uniform film formation are required to avoid defects such as bubbling and orange peel. Controlling the emulsion particle size to 0.1–0.2 μm helps improve drying speed and film density. Strong adhesion and abrasion resistance Finished cigarette packs undergo processes such as folding, creasing, and stacking. The ink must possess excellent adhesion and abrasion resistance to prevent ink splattering or delamination. Styrene-acrylic polymer emulsions excel in this regard. Good Compatibility with Ethanol Systems In actual printing, ethanol is often added to adjust drying speed and viscosity. The emulsion must have excellent alcohol solubility to avoid demulsification or flocculation. Some products can be diluted with ethanol in any proportion and have good reconstitution properties. Environmental Compliance and Safety Free of APEO, heavy metals, and carcinogenic aromatic amines, meeting food-grade packaging safety requirements, suitable for high-hygiene-standard fields such as tobacco, alcohol, and pharmaceuticals. III. Quality Control and Storage Management Testing Items: Each batch should be tested for key parameters such as solid content (48±1%), viscosity (800–2000 cps), pH value (7–9), and particle diameter (0.1–0.2μm). Storage Conditions: Sealed and protected from light, avoid freezing and high temperatures. Recommended storage temper...