Auxiliaries for waterborne polyurethane
01Stabilizing additives
Stabilizing additives are substances that enhance the stability of waterborne polyurethane materials. Waterborne polyurethane materials, the major defect is its poor aging resistance, which hinders the use and development of the product, therefore, the exploration of aging resistance of waterborne polyurethane materials is throughout the research and development of waterborne polyurethane materials. Therefore, the problem of anti-aging of waterborne polyurethane materials must be treated correctly, in fact, it is necessary to pay attention to the research of waterborne polyurethane stabilizing additives.
02 Improvement of mechanical properties additives
This type of additives is to enhance the waterborne polyurethane material some specific physical properties of the substance. Waterborne polyurethane material itself is not any performance is so significant, the only additives will have the value of use.
03Processing performance improvement additives
Waterborne polyurethane materials have many characteristics of the material itself, such as viscosity, which makes processing more complicated, therefore, in the processing and use of waterborne polyurethane, it is more and more critical to improve the processing performance of the additives.
04Auxiliaries to improve surface properties and appearance
Waterborne polyurethane has antistatic agents with antistatic effects, whitening agents for coatings, and sliding agents.
05Flame retardant additives
Auxiliaries that make materials incombustible or prevent materials from burning.
06Auxiliaries to improve flow and rheological properties
Waterborne polyurethane materials have different requirements according to the differences in the applicable objects. Such as wood adhesive due to the porous nature of the material, the viscosity of the water-based polyurethane adhesive is required to be large enough to avoid the glue to penetrate into the internal structure of the wood and it is difficult to ensure the amount of sizing, at this time, it is necessary to add thickening agent.
Polyurethane adhesive manufacturing in addition to isocyanate and polyol basic raw materials, add a variety of additives is also very important. Additives can be selected production process, improve the adhesive sizing process, improve product quality and expand the scope of application.
Solvent
In order to adjust the viscosity of polyurethane adhesive, easy to process operation, in the preparation process of polyurethane adhesive or formulated for use, often use solvents. Organic solvents for polyurethane adhesives must be “urethane grade solvents”, which basically do not contain water, alcohols and other active hydrogen compounds. “Urethane grade solvent” is the isocyanate equivalent as the main indicator, that is, the consumption of 1 mol of NCO-based solvent required for the number of grams, the value must be greater than 2,500, less than 2,500 below is unqualified. Therefore, the purity of solvents used in polyurethane adhesives is higher than that of general industrial products.
Polyurethane adhesive solvents usually include ketones (milk methyl ethyl ketone, acetone), aromatic hydrocarbons (such as toluene〉, dimethyl formamide, tetrahydrofurfura, etc.. The choice of solvent can be based on the principle of solubilization of polyurethane molecules and solvents – that is, similar solubility parameters SP, similar polarity, and the solvent itself, such as the rate of volatilization and other factors to determine. Can use mixed solvents to improve solubility, adjust the volatilization rate to adapt to the requirements of different bonding processes.
Physical properties of solvents commonly used in polyurethane adhesives
Catalyst
The preparation of polyurethane resin there are mainly three kinds of reaction need catalyst: NCO/NCO, NCO/OH, NCO/H2O. the manufacture of polyurethane adhesive mainly need to use NCO/OH reaction catalyst and NCO/H2O reaction catalyst.
