Current problems with waterborne polyurethane adhesives: (1) Low solid content: At present, the solid content of water-based polyurethane (WPU) can reach 45%. Fewer systems lead to higher drying and transportation costs. Increasing the solid content leads to an increase in the viscosity of the system, which makes emulsification and dispersion difficult. Reduced emulsion stability. (2) Slow drying and curing speed: The specific heat capacity and latent heat of evaporation of water are high, so the volatilization and drying of water are slow, resulting in long curing time of the adhesive, increasing energy consumption, and reducing production efficiency. (3) Poor wetting performance: The surface tension of water is three times greater than that of ordinary solvents. Using water as a solvent has poor wetting ability on low-energy surfaces. (4) Poor initial adhesion performance: The unmodified water-based polyurethane adhesive has a lower initial viscosity than the modified one, and has a greater impact on construction. (5) Poor water resistance and heat resistance: Most water-based polyurethane adhesives are linear thermoplastics, and their molecular chains contain hydrophilic groups, which results in poor water resistance and heat resistance. (6) Poor storage stability: The storage stability becomes worse as the solid content of the water-based polyurethane adhesive system increases and the degree of cross-linking increases. Sinograce Chemical is professional in the field of polyurethane coating, the quality is worthy of guarantee, the technology is worthy of trust. visit us sinograce chemical: https://www.sinogracechem.com Get a Quote Now :sales@sinogracechem.com Telephone               :+86 0551 63459511

Water based polyurethane resin refers to a binary colloidal system in which a polyurethane resin is dissolved or dispersed in water.Water-based polyurethane resin has the advantages of easy to use, stable performance, strong adhesion, excellent gloss, good heat resistance, etc. It can be suitable for various printing methods, especially suitable for screen printing, plastic packaging and composite films. The water-based polyurethane used in the ink industry requires good gloss, high bonding strength to materials, and good blocking resistance at a certain temperature.According to these performance requirements, there are the following requirements for the structural characteristics, functionality, synthetic formula, and process of polyurethane:(1) Select appropriate polyacids and polyols to synthesize polyester polyols with temperature resistance;(2) the introduction of polar groups with strong adhesion to the material;(3) Selecting suitable raw materials to improve the crystallinity of polyurethane;(4) Use coupling agents and other auxiliaries to improve the moisture and heat resistance of water-based polyurethane adhesives for inks. At present, water-based polyurethane inks have been commercialized, can meet a variety of performance requirements, and are receiving increasing attention.The application of water-based polyurethane inks is mainly flexographic printing and gravure printing. Water-based polyurethane inks widely used abroad have good environmental protection, stable ink properties, high viscosity, strong tinting power, and high fastness. need. Sinograce chemical produces polyurethane resin for various polyurethane coatings, such as water-based glue and water-based polyurethane waterproof coating visit us sinograce chemical: https://www.sinogracechem.com Get a Quote Now :sales@sinogracechem.com Telephone               :+86 0551 63459511

Waterborne paint testing and standards:hardness Hardness is one of the most important physical properties of a coating. Coating hardness reflects the coating's ability to resist constant dents, scratches, scribes, and penetrations caused by a hard object. Testing the hardness of materials with different methods will give different results because the testing methods are for different amounts of materials, and each method has its own scale to determine the hardness characteristics of the material. Due to different emphasis, there is no absolute scale that can unify the hardness measured by different methods, but the results obtained by one method are comparable. The commonly used hardness test method for wood coatings is the pencil hardness method. The hardness side measured by pencil hardness test focuses on the coating's resistance to dents, scratches, and scratches. Although some people think that the technical content of pencil hardness is very low, but because it is simple and practical and can be directly measured on wood, the pencil hardness method is still widely used in the coating industry. Before the preparation of the sample, the wood should be polished, smoothed and cleaned. The dry thickness of the coating should be between 25 and 40 μm. It should be dried for 7 days after painting. The film thickness and long drying time affect the hardness test results. The set of pencils used for the test consisted of the hardest 9H to the softest 6B. Commonly used are 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, and 6B. F is the intermediate hardness, etc., "H," means "Hardness", "B" stands for "Blackness" The hardness of a pencil is determined by the ratio of graphite and clay used in the manufacture of lead cores. The darker, the softer; the more clay, the harder the lead core made. The hardness number of the pencil is used to indicate the hardness of the paint film. Test the pencil first to remove the wooden rod to expose a lead of about 3mm in length. The pencil should be ground vertically on the sandpaper to make a flat surface, and the edges should be sharp. Hold the pencil so that it is 45 degrees from the paint surface to be tested. Corner, apply pressure, and continuously draw the pencil lead on the paint surface. Each hardness pencil is measured 5 times on the sample, each time with a new sharp-lead lead, find the pencil number that scratched or scratched the paint at least 2 out of 5 times, and then use a soft The number one pencil test, if you get no more than one sting or scratch, the latter number is set as the hardness of the coating. In order to eliminate the deviation caused by uneven force and angle of holding the pencil, various pencil hardness testers have been put on the market. The range of pencil hardness grades has a wide range, which cannot reflect the small hardness difference between paint lacquers, that is, the actual soft hardness of paint films with the same pencil hardness may be significantly different. However, the pe...

Spraying construction paint film than brush paint film more flat. Spray with water-based wood paint should be added on the basis of the original paint 5% ~ 30% of the tap water dilute after use, for the viscosity of the paint water should also increase, the diluted paint after its coating a 4 cup viscosity should be around 18 ~ 20s. Dilute mix well should be static at least 20 minutes, until the bubbles into the basic disappearance of coating. Before spraying the paint must be more than 200 mesh filter, so as not to bring impurities, affecting the quality of paint film. Water - based paint can be used ordinary spray machine or high - pressure airless spray machine construction. Pay attention to not too fine atomization, but also to prevent bad atomization. The amount of paint should not be too large, not spray too thick, wet film thickness around 50um is good, or easy to produce flow hang, orange peel and other ills. Water-based paint spraying common mistake is a construction too thick, if you want to increase the film thickness, it is appropriate to use multiple spraying method. When spraying on the vertical surface, the spray gun should be slightly at an Angle to the construction surface. Avoid excessive spraying on the vertical surface to avoid sagging. The two paints must be sanded with more than 400# sandpaper. The compressed air is blown off and cleaned with a damp cloth, which increases the adhesion between the two paint films. Sinograce chemical industry co., LTD. Specializes in producing waterborne coatings, waterborne wood lacquer, etc. To learn more, please click here visit us sinograce chemical: https://www.sinogracechem.com Get a Quote Now :sales@sinogracechem.com Telephone :+86 0551 63459511