Defoamer is one of the most difficult additives in waterborne wood coatings to control the balance between defoaming and leveling.The paint liquid will generate bubbles during the application due to agitation .If the bubbles present in the paint are not removed in time, the film will dry and form an unacceptable flaw.The paint also produces air bubbles during production, pumping and filling. Defoaming is a non-negligible factor in the formulation design process. The defoaming mechanism of the defoaming agent is to penetrate the foam film produced by the system by wetting and continuously spread on the film, so that the surface tension of the foam film is unbalanced and broken bubble.Generally speaking, the defoaming agent is divided into two types, a suds suppressor and a defoaming agent. The function of the suds suppressor is to inhibit the foaming of the waterborne wood coating under the action of an external force, and the defoaming agent is mainly on the surface of the foamed film. Rapidly spread, destroy the elastic membrane of the bubble, and make it rupture, but often the effect of the two combinations is better, otherwise at least one effective defoamer should be selected.Most antifoaming agents, especially silicone defoamers, will cause shrinkage of the wet paint film when the dosage is too large. Therefore, the amount of defoaming agent can be basically eliminated by the principle of eliminating bubbles, so that the defoaming effect cannot be excessively pursued. Side effects such as shrinkage holes. For waterborne wood lacquers, mineral oil defoamers are more tolerant than silicone defoamers, and adding a little more is not prone to severe shrinkage, which can be preferred. Sinograce Chemical produces water based additives, such as thickener, crosslinking agent, wetting agent.

The film-forming aids for waterborne wood coatings are generally alcohol ether type solvents. The most commonly used filming aids such as diethanol ethers, propylene glycol ethers and N-methylpyrrolidone have high and low boiling points.Water-based wood coatings in the summer construction, the water volatilization is faster, that is, the surface is relatively fast, some of the moisture may be enclosed in the coating film before drying, resulting in white coating or poor leveling.Therefore, it is possible to delay the drying speed of the coating film by adding a small amount of a suitable and suitable high boiling point solvent, to extend the opening time of the coating film, and to improve the workability and the appearance of the coating film. In winter, due to the lower temperature, the drying speed of waterborne wood coatings is slower, that is, the evaporation of water is slower, but the filming aids are relatively faster than water, and some may evaporate with water, so that waterborne wood coatings cannot The formation of a dense coating results in blushing and cracking of the coating of the aqueous wood coating.Therefore, when adding a film-forming auxiliary, it is necessary to consider overcoming the workability of the water-based wood coating in different seasons, and also considering the drying speed as much as possible. This is also the most difficult technical point of the water-based wood coating, especially the high Tg. Acrylic dispersion is more difficult to solve.Therefore, a variety of filming aids to match is the best choice. The film-forming auxiliaries have a problem of compatibility with the visit us sinograce chemical: https://www.sinogracechem.com Get a Quote Now :sales@sinogracechem.com Telephone               :+86 0551 63459511

Formulation design system for waterborne coatings - film forming AIDS The polymer constituting the emulsion or dispersion generally has a glass transition temperature higher than room temperature. In order for the emulsion particles to be well fused into a uniform paint film, it is necessary to reduce the minimum film formation temperature (MFFT) of the crystallization aid.Film forming agents are a kind of small molecular organic compounds, the film forming agents in the paint film will eventually gradually escape and volatilize most of the film forming agents is an important part of coating VOC, so the less film forming agents should be used, the better.The use of film-forming auxiliaries should give priority to compounds that are not within the VOC limits, but which are not too slow in volatility and have high film forming efficiencies.The amount of coalescent aid depends on the amount of emulsion or aqueous dispersion in the formulation and the glass transition temperature.The amount of the emulsion or water dispersion is large and the Tg of the polymer is high, and the amount of the film-forming auxiliary agent is also large. On the contrary, when the dosage is small, the formulation aid is first considered to account for about the emulsion or the aqueous dispersion. %-5%, or 5% to 15% of the emulsion or dispersion solids.However, for polymer emulsions with Tg over 35  C, it may be necessary to increase the amount of coalescent to ensure the reliability of low-temperature film formation. At this time, the amount of film-forming auxiliary should be gradually increased until low temperature (about 10   C or lower). The coating can form a uniform paint film without cracking or powdering, and find the minimum amount of filming aid.It is not advisable to use a filming aid in an amount of 15% or more of the emulsion or dispersion. It should be considered to replace other filming aids and try again.In addition to lowering the minimum film forming temperature and increasing the density of the film, the filming aid can improve the workability, increase the leveling of the paint, prolong the opening time, and improve the storage stability of the paint, especially the low temperature freeze resistance. Sinograce Chemical produces water based coating,Water-based glue, polyurethane coating visit us sinograce chemical: https://www.sinogracechem.com Get a Quote Now :sales@sinogracechem.com Telephone               :+86 0551 63459511

In the formulation of waterborne wood lacquer topcoats, the binder is a key component in forming the film and determining the properties of the film. The binder, ie the polymer emulsion, dispersion or hybrid, accounts for more than 80%, preferably more than 90%.Since the solid content of the emulsion, especially the aqueous dispersion is relatively low (the aqueous dispersion is generally 30% to 35%), the amount of the base material should be increased as much as possible in the formulation design so that the effective film-forming material content in the paint liquid is as large as possible. In this way, it is ensured that the painted paint is thicker and has a high fullness. Polymer emulsions generally have a higher solids fraction than aqueous dispersions. After the solid content of the water-based base material is increased to a certain extent, the viscosity is so fast that it can be thickened to the extent that the paint cannot be smoothly produced.Since the particles in the aqueous dispersion region are small, this phenomenon is more remarkable, and it is usually only a concentration of 35% or less.Because the emulsion particles are relatively large, the viscosity of the same solid is smaller, and generally a solid fraction of about 50% can be produced.When formulating the formula, this difference should be taken into account, that is, when using a water-dispersible lacquer, it is necessary to increase the amount of the dispersion as much as possible.Which emulsion or aqueous dispersion to use depends on the purpose of the waterborne wood lacquer.Outdoor water-based wood lacquers have harsh weathering conditions, and aliphatic polyurethane dispersions or acrylate emulsions should be preferred.The interior paint can be made of an aromatic polyurethane dispersion or an acrylate emulsion, which has a high glass transition temperature or can be crosslinked during the curing process to improve water resistance and ironing resistance. There are some pigments and fillers in the water-based wood paint solid paint. The amount of emulsion or water dispersion is correspondingly reduced, generally about 70%-80%, while the putty has more fillers, and The amount of emulsion or dispersion can even be as low as 50%. The types of resins that have been successfully applied to waterborne wood coatings are mainly waterborne alkyds, acrylic emulsions or dispersions, aqueous polyurethane dispersions and aqueous acrylic polyurethane dispersions. Sinograce Chemical produces water based coating,Water-based glue, polyurethane coating visit us sinograce chemical: https://www.sinogracechem.com Get a Quote Now :sales@sinogracechem.com Telephone               :+86 0551 63459511