What does minimum film formation temperature mean?

Minimum Film Formation Temperature (MFT) is the lowest temperature at which the polymer particles in an emulsion are active enough to coalesce with each other to form a continuous film. In the process of forming a continuous film from a polymer emulsion, the polymer particles must form a close-packed arrangement. Thus, the conditions for the formation of a continuous film in addition to the emulsion needs to be well dispersed, but also the deformation of the polymer particles, that is, when the capillary pressure of water between the spherical particles to generate considerable pressure, the closer the spherical particles are lined up, the greater this pressure will be added. When the particles are in contact with each other, the pressure generated by the volatilization of water forces the particles to be extruded and deformed and bonded to each other to form a coating film.

Harder agent emulsion such as its polymer particles for most of the thermoplastic resin, then the lower the temperature, the greater the hardness, the more difficult to deform, so there is a minimum film-forming temperature of the problem. That is, below a specific temperature conditions, the emulsion of water evaporation, the polymer particles are still discrete state, and can not be fused together, and therefore the emulsion can not be evaporated because of the water to form a continuous uniform film; and above this specific temperature, in the evaporation of water, the polymer particles in the molecules will penetrate, diffusion, deformation, aggregation of the formation of a continuous transparent film. The lower limit of the temperature at which a film can be formed is called the minimum film-forming temperature.

The minimum film-forming temperature is an important indicator for polymer emulsions, and it is particularly important to use emulsions during the low-temperature season. Take appropriate measures to make the polymer emulsion has to meet the requirements of the use of the minimum film-forming temperature, such as the addition of plasticizers in the emulsion can make the polymer soften, so that the minimum film-forming temperature of the emulsion significantly lower, or the minimum film-forming temperature of the polymer emulsion of the use of additives, etc. higher. The minimum film-forming temperature is also an important indicator of paint construction. Generally speaking, the lower the minimum film-forming temperature, the better the workability.

The minimum film-forming temperature of the emulsion for the coating hardness, glass transition temperature and low-temperature coating performance has an important impact, the minimum film-forming temperature is high, the coating hardness is high, the gloss is high, but for the coating of the coating has a negative impact, the minimum film-forming temperature is too low, the corresponding glass transition temperature is low, high temperature conditions, the coating is easy to soften, there will be a certain degree of viscoelasticity, resulting in a reduction in the coating of the stain resistance properties.

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