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    Home > Coatings News > Paints and Coatings Market > General knowledge of coating: dispersion effect of pigment and evaluation of color paste in automobile coating production

    General knowledge of coating: dispersion effect of pigment and evaluation of color paste in automobile coating production

    • Last Update: 2020-04-03
    • Source: Internet
    • Author: User
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    The main points are as follows: 1

    The evaluation methods of pigment dispersion are fineness board and white wash, the other methods are spray coating and observation of color phase migration

    Fineness board is the most commonly used method to control the degree of pigment grinding in the coating production process, which is generally used in production to determine whether the pigment grinding has met the requirements

    This method is fast and convenient

    For pigment dispersion, fineness control is the most basic requirement

    If the grinding fails to meet the fineness requirements, the performance of the paint film may not meet the requirements

    In addition, for some requirements, the fineness should be controlled within Paint knowledge how about Akzo Nobel Powder Coating Recommended introduction: powder coating is a kind of coating with different form from general coating, which is in powder form

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    Since the introduction of this technology, powder coating has been able to continue to maintain the Paint Home News: first, the evaluation method of excellent pigment dispersion effect the commonly used test and evaluation methods of pigment dispersion are fineness board and white wash, the other methods are spray coating and observation of color phase migration

    Fineness board is the most commonly used method to control the degree of pigment grinding in the coating production process, which is generally used in production to determine whether the pigment grinding has met the requirements

    This method is fast and convenient

    For pigment dispersion, fineness control is the most basic requirement

    If the grinding fails to meet the fineness requirements, the performance of the paint film may not meet the requirements

    In addition, the fineness plate is not suitable for some grinding that requires the fineness to be controlled at nanometer level

    White dilution is a common experimental method to evaluate the dispersion state of colored pigments, especially for evaluating the dispersion state of color paste

    After the color paste and white paint are mixed, finger rub test shall be carried out during construction to observe the floating color and blooming of paint film

    What should be noted here is the dispersion stability of the white base paint itself

    The dispersion of titanium dioxide is easier than other colored pigments, but it does not mean that no dispersant is needed

    Although it seems that the appearance of the final white paint will not be greatly affected by the use of dispersants sometimes, when the poorly dispersed white paint is added to the color paste, a very serious phenomenon of floating color and blooming will occur

    Therefore, in order to judge the dispersion state of the colored pigment, it is necessary to ensure the dispersion stability of the pigment itself

    Compared with other construction methods, spray coating has the characteristics of no need of any machinery and equipment and easy operation

    Not only that, the method has high practicability for evaluating pigment dispersion, because of the very low shear force in the method

    Coating is a complex mixture with many different components

    Under the condition of low shear, the components in the coating tend to separate from each other, so under the condition of high shear, the coating is prone to sedimentation, water, floating color and other defects

    In the high shear state, the components in the coating are fully mixed evenly, thus reducing the occurrence of various defects

    The results show that when the same coating is applied in different ways, the gloss, haze, transparency and other properties of the spray coating film are much better than that of the spray coating film

    On the other hand, when the film obtained by spraying has a good performance, the actual construction has a higher safety factor

    2、 The evaluation methods of pigment dispersion mentioned above are all suitable for color paste

    In addition, there are other requirements to be met

    (1) Fluidity: the pigment concentrate slurry shall have good rheological property, namely fluidity, which can be pumped for batching and metering

    (2) Reproducibility: the production of pigment concentrate must have reproducibility, and the change of coloring power shall not exceed 2%

    (3) Storage stability: the pigment concentrate must be stored stably, that is, there is no sedimentation, seepage and flocculation

    They should also show no viscosity increase or tendency to dry out

    (4) Applicability: pigment concentrate must be easily added to different base material systems without granulation, even with a relatively low shear

    There should be no or only a little floating color or hair in the finished product drawing

    The film performance of the finished drawing shall not be reduced

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