Common problems and analysis when applying paint colour paste
I. Colour paste added to paint, colour floats on the surface
Reasons:
(1) The difference in surface tension between colour paste and paint is too large paint generally with anionic or ionic polyelectrolyte dispersant, while colour paste is generally mostly used non-ionic or with part of the anionic dispersant and make white pigment and coloured pigment surface adsorption of different wetting dispersant, with different surface tension.
(2) Colour paste and paint compatibility is not good emulsifier outside the emulsion particles and the surface active agent outside the face and filler particles are not compatible, resulting in the flocculation of pigments.
3) Mismatch between colour paste and paint hydrophilic and oleophilic balance values oleophilic substances have a small surface tension at their oleophilic end and float to the surface more easily.
(4) The influence of thickening agent some pseudoplasticity strong conjoining thickening agent and HLB value larger surfactant has a great affinity, make it in the pigment surface desorption, cause the pigment aggregation and flocculation, produce floating colour hair flower.
Solution: The best way to control floating colours is to choose suitable wetting and dispersing agents, adjust the surface properties of the particles and regulate their balance of movement. Such as coloured pigment flocculation, floating white, pigment flocculation floating colour, can use wetting and dispersing agent to alleviate flocculation, improve the surface properties of the particles to prevent or control floating colour, in the process of controlling floating colour several floating colour phenomenon can be mutually transformed, control floating colour. If the floating colour is the colour of the colour paste, it means that the HLB value of the paint is larger than the hydrophilic, and the base paint preparation process adds oleophilic low-polarity additives to reduce the HLB value of the paint; if the floating colour is white, it means that the HLB value of the paint is smaller and more oleophilic, and the base paint preparation process adds hydrophilic additives to increase the hydrophilic nature of the paint. Certain systems can be anti-floating colour in the coating film, adding anionic wetting and dispersing agents in the finished paint, adsorbed on the surface of the carbon black or organic violet pigment particles, improving the surface properties of the pigment particles and enhancing the polarity, these non-polar weakly polar particles have the same polarity as the white particles, with the same degree of adsorption flocculation as the polymer, and thus have comparable movement in the drying of the coating film, controlling the floating colour. A surfactant that strongly reduces surface tension, commonly a silicone surfactant, is selected so that it migrates to form a single molecular film on the surface as the film dries, balancing surface tension and controlling bloom; however, it is possible that floating colours may still be present. Add some additives that can produce thixotropic structures, such as kaolin, or silica, to form a network structure in the paint film, to prevent the separation of pigments, control the pigment flocculation, settlement and Benard spiral flow, to reduce the phenomenon of floating colour and flowering, thus preventing floating colour or flowering.
Second, the colour paint on the wall roller coating in the obvious roller marks
Causes:
1) Uneven thickness during painting operation
(2) Construction without wet joint
(3) compatibility problems
4）Insufficient amount of emulsion in the emulsion paint
5) Insufficient amount of emulsion in the emulsion paint
6) The wall is not constructed in one go
Solution: mainly for compatibility problems
1) Mechanical dispersion (colour paints) Colour paint colours can be shown under certain mechanical force dispersion.
2) Adding wetting agent (colour paint) After adding wetting agent, the colour becomes much darker, the finger study colour difference becomes smaller, and there is no obvious brush mark after brushing the board.
(3) adjust the paint formula (basic paint) to change the wetting and dispersing thickening system of paint to solve the compatibility problem of paint and colour paste.
Third, after the rain there are obvious rain marks on the surface of the colour paint
Reasons:
1) poor water resistance of base paint (emulsion hydrophilic too strong, excessive wetting agent or hydrophilic auxiliary dosage is too large) 2) the substrate contains too much water or environmental humidity is too large
3) Closure primer, not achieved the effect
4) The coating film is not completely dry before the water is flushed
5) Too much residual additives in the dark paint
Prevention methods:
1）Use surfactants as little as possible, use silicones as much as possible to reduce moisture absorption.
2) Use fluorine modified resins or additives to enhance water repellency and anti-fouling properties.
3) Use emulsions with good water resistance.
(4) Paint the surface with glossy varnish.
4、After the rain, the surface of the colour paint has obvious colour loss
Reasons:
1) Insufficient time for the paint film to dry, less than 2 hours after the construction of the rain.
2) The PVC concentration of the paint is too high, i.e. the emulsion is too low or the filling amount is too high.
3) Very poor water resistance of the paint film.
Solution:
1) Increase the content of the emulsion.
2) Choose an emulsion with good water resistance.
V. After a period of time, the wall surface is obviously faded (flowering)
Causes:
1) The emulsion content of the paint is low.
2）The water resistance of the paint is not good.
3) Improper choice of colour paste.
4) Dark colours will also show a lighter colour if the paint film is chalked.
5) Colour migration (migration to the inside).
6) Poor drying rate due to conditions such as sun and temperature of construction work.
7) Insufficient flatness, under the influence of lustre causing poor vision from a distance.
Solution:
1) Increase the emulsion content in the paint.
2) Choose a colour paste with good weather resistance.
3) Engineering conditions control.
VI. Unable to mix the required colour
Causes:
1）Inappropriate titanium white content (colours with poor coverage cannot be exhibited).
(2) Improper choice of colour paste (some colours cannot be replaced by other colour pastes).
3) Colour migration.
Solution:
1) Choose the right paint with the right titanium white content.
2) Choose a colour paste with good compatibility.
