JP5958312B2 - Setting method of laminated coating film specifications - Google Patents

Description

  The present invention relates to a laminated coating film in which a specific color is developed in a predetermined manner by a first base coating film that conceals a base and a second base coating film having visible light transmittance, and for the coating thereof. It relates to a method for setting specifications.

  In recent years, for objects to be coated such as automobiles that require high designability, for example, it is desired to obtain a coating color having high saturation and strong depth. In automobiles, two-coat one-bake or three-coat one-bake is used to paint the car body. The first base coating film is a metallic base layer that contains a pigment and a glittering material and conceals the base, and the second base coating film contains a pigment. The design is realized by using a color clear layer that contains and has visible light transmittance.

For example, in Patent Document 1, in a laminated coating film in which a colored base coating film and a transparent clear coating film are laminated on a metallic base coating film, color unevenness due to film thickness variation, occurrence of a frame phenomenon, and polishing It is described that the specifications of the laminated coating are set so as to suppress hue change due to repair and to obtain a sense of color and depth. Specifically, the lightness L ^* value of the metallic base coating film is set to 60 or less, the light transmittance at a wavelength of 400 nm to 700 nm of the colored base coating film is set to 30% to 50%, and the film thickness of the colored base coating film is set. The thickness is 5 μm or more and 20 μm or less, and the thickness of the clear coating film is 25 μm or more and 45 μm or less.

Japanese Patent No. 4727411

  By the way, when a specific color is developed in a predetermined manner by the first base coating film concealing the base and the second base coating film having visible light transmittance, the first base coating film and The hue of each second base coating film is determined, and the film thickness, pigment concentration, etc. of the second base coating film are set so that the intended color development is obtained.

  However, in order to determine the hues of the first base coating film and the second base coating film that match the color development intention, and to determine the film thickness and pigment concentration of the second base coating film, trials were performed with various coating conditions changed. It needs to be repeated, and it takes a lot of labor and cost and requires skilled skills. In particular, in actual coating, when the target film thickness is determined and the second base coating film is applied, the target film thickness does not necessarily become the target film thickness. There may be some deviation, and there may be cases where the desired coloring effect cannot be obtained due to this film thickness variation.

  Therefore, the present invention relates to a laminated coating film obtained by laminating a second base coating film on a first base coating film, and provides a method for easily setting specifications for developing a specific color in a predetermined manner.

  In order to solve the above-mentioned problems, the present invention is a color space on which the coating color of a laminated coating film changes exponentially with the colorant (pigment or dye) concentration and film thickness of the second base coating film as variables. A model represented by color coordinate values was set, and specifications for developing a specific color were set based on this model.

That is, a preferable method for setting the specifications of the laminated coating film presented here includes a first base coating film containing a pigment or a dye as a colorant and concealing the base, and a colorant laminated on the upper side of the first base coating film. In a laminated coating film which contains a pigment or a dye and has a visible light transmittance and a specific color is developed by the second base coating film, a method for setting specifications for the color development,
Setting a model that expresses the coating color of the laminated coating film as a color coordinate value N on a color space that changes exponentially with the colorant concentration X and the film thickness Y of the second base coating film as variables;
Setting an upper limit TH and a lower limit TL of target color coordinate values for causing the specific color to be developed by the laminated coating film;
Setting a target film thickness Yt during actual coating of the second base coating film and a film thickness variation rate Z based on the target film thickness Yt;
Based on the model, when the film thickness Y of the second base coating film is the lower limit value of the film thickness fluctuation range, the color coordinate value N becomes the lower limit TL of the target color coordinate value, and the second base coating film The first base corresponding to the film thickness variation rate Z under the condition that the color coordinate value N is the upper limit TH of the target color coordinate value when the film thickness Y is the upper limit value of the film thickness variation width. And a step of setting a color coordinate value B1 of the coating film and a colorant concentration X of the second base coating film.

For example, in the step of setting the model, the following coloring model formula (1) expressing the coating color of the laminated coating film as a color coordinate value N in a color space is set,
N = P− (P−B1) × exp (−AXY) (1)
(However, P is a color coordinate value that provides 100% concealment (complete concealment) in the color space, X is a colorant concentration (mass fraction) of the second base coating film, and Y is the second base coating film. The film thickness (μm) and A are obtained by substituting the measured N value, P value, B1 value, X value and Y value for the laminated coating film sample prepared using the colorant into the model equation (1). The coloring power of the above-mentioned coloring agent.)

  When the film thickness of the second base coating film is Yt (1 + Z), the color coordinate value N is the upper limit TH of the target color coordinate value, and the film thickness of the second base coating film is Yt (1-Z). Of the first base coating film according to the film thickness variation rate Z based on the model equation (1) under the condition that the color coordinate value N is the lower limit TL of the target color coordinate value. The color coordinate value B1 and the colorant concentration X of the second base coating film are set.

  According to the inventor's research, the color coordinate value N of the laminated coating film increases logarithmically as the film thickness Y of the second base coating film increases. Further, the logarithmic increase becomes gentler as the colorant concentration X of the second base coating film becomes lower, and becomes slower as the color coordinate value B1 of the first base coating film becomes higher.

  Therefore, the model equation (1) is negative so that the color coordinate value N of the laminated coating film increases logarithmically as the colorant concentration X and the film thickness Y of the second base coating film increase. An increase function of the color coordinate value N is approximated by an exponential function having the number “−AXY” as an index, and the logarithmic increase is set to be gentler as the color coordinate value B1 of the first base coating film is higher. doing.

Here, since the film thickness variation of the second base coating film is unavoidable in actual coating, the color coordinate value N of the obtained multilayer coating film has the upper limit TH of the target color coordinate value even if the film thickness variation occurs. It must be ensured that it does not exceed and does not fall below the lower limit TL of the target color coordinate value. That is, a film thickness ranging from the thickness Y _L for the lower limit TL is obtained until the film thickness T _H of the upper limit TH is obtained is permitted to the second base coating film.

On the other hand, of course, the more slowly logarithmically increasing color coordinate value N of the multilayer coating film, the difference between the thickness T _H having a thickness above the lower limit TL is obtained Y _L and the upper limit TH is obtained In other words, the film thickness variation rate Z allowed for the second base coating film increases.

  As described above, as the color coordinate value B1 of the first base coating film increases, the logarithmic increase in the color coordinate value N of the laminated coating film becomes gradual, and as the logarithmic increase increases, the second base coating film increases. Since the allowable film thickness fluctuation rate Z increases, the film thickness fluctuation rate Z of the second base coating film corresponds to the color coordinate value B1 of the first base coating film.

  Accordingly, given the P value, the upper and lower limits TH and TL of the target color coordinate value, and the film thickness variation rate Z of the second base coating film, the color coordinate value B1 of the first base coating film is obtained.

  When this point is seen in the model equation (1), when the upper limit TH, the lower limit TL, and the film thickness variation rate Z are given thereto, the following equations (2) and (3) are obtained.

TL = P− (P−B1) × exp {−AXY (1-Z)} (2)
TH = P− (P−B1) × exp {−AXY (1 + Z)} (3)

  When this simultaneous equation is solved for B1, the following equation (4) is obtained, and it is understood that the color coordinate value B1 of the first base coating film is obtained.

B1 = P-{(P-TL) ^{1 + Z} / (P-TH) ^1-Z } ^{1 / 2Z} (4)

  Further, given the P value, the upper limit TH and the lower limit TL of the target color coordinate value, the coloring power A of the colorant, the target film thickness Yt, and the film thickness variation rate Z, the colorant of the second base coating film A concentration X is obtained.

  That is, when the simultaneous equations of the equations (2) and (3) derived from the model equation (1) are solved for AXY, the following equation (5) is obtained, and the coloring power A of the colorant and the target are obtained as the values of AXY. It can be seen that when the film thickness Yt is given, the colorant concentration X of the second base coating film is obtained.

    AXY = (1 / 2Z) · ln {(P-TL) / (P-TH)} (5)

  The first base coating film is preferably a metallic base coating film containing the colorant and a glittering material.

  The second base coating film has a light transmittance of 55% or more for the specific color. The hue of the specific color is set to the median value of the Munsell hue ring. When the hue range of −25 or more and +25 or less when the hue range is displayed is defined as the hue range of the specific color, it is preferable that the average light transmittance in a wavelength region outside this hue range is 50% or less.

  According to the present invention, a first base coating film containing a pigment or dye as a colorant and concealing the underlayer, and a pigment or dye as a colorant laminated on the first base coating film and transmitting visible light. In the laminated coating film in which the specific color is developed in a predetermined manner by the second base coating film having the property, the specifications for the color development can be easily and efficiently set.

It is sectional drawing which shows the structure of a laminated coating film typically. It is a graph which shows the relationship between the film thickness in a 2nd base coating film independent, and a color coordinate value. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, and the color coordinate value N of a laminated coating film. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, and the color coordinate value N of the laminated coating film based on a model formula. It is a graph which shows the relationship between the upper limit TH and lower limit TL of a target color coordinate value, and a film thickness fluctuation range. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, and the L coordinate actual value of a laminated coating film. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, and the a coordinate actual value of a laminated coating film. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, and b coordinate measured value of a laminated coating film. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, and the conversion L coordinate value of a laminated coating film. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, and an AXY calculation value. It is a graph which shows the relationship between the film thickness of a 2nd base coating film, the measured value of L coordinate value, and a theoretical value. It is a graph which shows the relationship between the film thickness fluctuation rate of a 2nd base coating film, and L coordinate value B1, B2 of a 1st base coating film and a 2nd base coating film when the tolerance | permissible_range of a target color coordinate value is wide. . It is a graph which shows the relationship between the film thickness fluctuation rate of a 2nd base coating film, and L coordinate value B1, B2 of a 1st base coating film and a 2nd base coating film when the tolerance | permissible_range of a target color coordinate value is narrow. .

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

  FIG. 1 schematically shows an example of a laminated coating film 2 provided on the outer surface of a car body (steel plate) 1 of an automobile. The laminated coating film 2 is formed by laminating a first base coating film 4, a second base coating film 5, and a transparent clear coating film 6 in this order. The first base coating film 4 is a metallic base coating film containing a bright material 7 and a pigment 8 as a colorant. The second base coating film 5 contains a pigment 8 as a colorant. An electrodeposition coating film 3 is formed on the surface of the vehicle body 1 by cationic electrodeposition coating, and an intermediate coating film 9 is formed on the electrodeposition coating film 3, and the laminated coating film 9 is formed on the intermediate coating film 9. 2 is provided.

  This laminated coating film 2 includes a first base coating film 4 that hides the base (intermediate coating film 9), and a second base coating film that is directly laminated on the surface of the first base coating film 4 and has visible light transmittance. A specific color is developed by the film 5. The second base coating film 5 preferably has a light transmittance of a specific color of 55% or more and 70% or less. The hue of the specific color is set to the median value of the Munsell hue ring. When the hue range of −25 or more and +25 or less when the hue range is displayed at 50 is defined as the hue range of the specific color, the average light transmittance in a wavelength region outside this hue range is preferably 50% or less.

<Example of coloring mechanism>
The color development mechanism of the first base coating film 4 and the second base coating film 5 will be described in the case where red pigment 8 is used as a colorant and red is developed as a specific color.

  The light transmitted through the clear coating 6 enters the second base coating 5. For example, the second base coating film 5 has a function of transmitting as much red light as possible and a function of absorbing light of colors other than red as much as possible in order to achieve high saturation and high brightness. The main control factors for this are the type of pigment 8 and the amount (concentration, film thickness) of pigment 8. The wavelength characteristic of the light transmittance varies depending on the type of the pigment 8. When the amount of the pigment 8 increases, the transmittance of red light does not decrease so much, but the transmittance of light other than red decreases (light other than red is well absorbed).

  The light transmitted through the second base coating film 5 is reflected by the first base coating film 4. For example, the first base coating film 4 has a function of increasing the FF (flip-flop) in order to increase the sense of depth, and a function of reflecting red light and preventing reflection of light other than red as much as possible in order to increase the saturation. The main control factors for giving a sense of depth are the type of the glitter material 7 (the glitter material type, particle size or aspect ratio), the amount of the glitter material 7 (concentration, film thickness), and the orientation of the glitter material 7. The main control factors for increasing the saturation are the kind of pigment 8 and the amount (concentration, film thickness) of the pigment 8 as in the case of the second base coating film 5.

  The light reflected by the first base coating film 4 passes through the second base coating film 5 and further passes through the clear coating film 6 and goes out.

<Setting of coating specifications for laminated coating film>
1. Coloring model formula setting (construction)
The coloring power (coloring power) of the second base coating film 5 by the colorant can be expressed as follows.

    Coloring power of coating film = Coloring power per unit film thickness × film thickness Y

  “Coloring power per unit film thickness” can be expressed as “colorant coloring power A × colorant concentration X”. Therefore:

    Color strength of coating film = colorant coloring power A × colorant concentration X × film thickness Y

  Here, the coloring power A is a coloring power unique to the coloring agent. The colorant concentration X is the colorant concentration of the second base coating film 5 expressed in mass fraction. The film thickness Y is the film thickness of the second base coating film 5, and the unit is μm.

According to the research of the present inventor, as shown in FIG. 2, the color of the second base coating film 5 alone is, for example, the Lab color system (“L ^* a ^* b ^* color system” is referred to as “ The color coordinate value is 100% concealed as the film thickness Y increases when the colorant concentration X is constant (when viewed on the a-axis, which is one of the color coordinate axes of “Lab color system”). The color coordinate value P at which complete concealment is obtained increases logarithmically as an asymptote (naturally, the same is true when the colorant concentration Y is increased while the film thickness Y is constant). The logarithmic increase in the color coordinate value a accompanying the increase in the film thickness Y becomes steeper as the colorant concentration X increases.

  Therefore, the logarithmic increase characteristic of the color coordinate value a can be approximated by an exponential function with a negative number “−AXY” as an index.

  Here, for convenience of explanation, the Lab color system is represented by the a-axis (one-dimensional), but the principle is the same regardless of whether it is three-dimensional or other color systems such as XYZ and RGB. .

  In the case of a laminated coating film in which the second base coating film 5 is laminated on the first base coating film 4, the color coordinate value of the coating color (this is referred to as “color coordinate value N”) is expressed by the following equation: Further, the color coordinate value B2 of the second base coating film 5 alone is added to the color coordinate value B1 of the first base coating film 4 alone.

    Color coordinate value N = B1 + B2

  That is, in the laminated coating film, the base level of the color coordinate value N is increased by B1 due to the coloring power of the first base coating film 4. As a result, the logarithmic increase tendency of the color coordinate value N accompanying the increase in the film thickness Y of the second base coating film 5 is as shown in FIG. In the figure, B1 (α) is a case where the coating color of the first base coating film 4 is close to the coating color of the second base coating film 5 (a case where the amount of colorant in the first base coating film 4 is large), B1 (β) is a case where the coating color of the first base coating film 4 is far from the coating color of the second base coating film 5 (a case where the amount of colorant in the first base coating film 4 is small).

  Therefore, in the present invention, based on the increase characteristic of the color coordinate value N, the color coordinate value N is approximated by the following coloring model equation (1).

    N = B1 + B2 = P− (P−B1) × exp (−AXY) (1)

  Here, the coloring agent coloring power A is obtained by substituting the measured N value, P value, B1 value, X value, and Y value for the laminated coating film sample prepared using the coloring agent into the model equation (1). Can be obtained. This point will be described later.

  For reference, in the model formula (1), when P = 100, B1 = 20, and A = 10, the colorant concentration X is 1% (mass fraction 0.01), and 2 FIG. 4 shows the change characteristics depending on the film thickness Y of the color coordinate value N in each case of% (mass fraction 0.02) and 3% (mass fraction 0.03).

2. Setting the upper and lower limits of the target color coordinate value of the multilayer coating 2 Create various samples with different coating conditions, and measure the color coordinate values of the samples from which the multilayer coating conforming to the color development intention was obtained with a colorimeter Then, the upper limit TH and the lower limit TL of the target color coordinate value are set.

3. Based from the average value Y _A of the average value Y _A Toko actually measured film thickness when performing coating of the second base coating film setting 5 thickness variation rate Z second base coating film 5 in the fluctuation width [Delta] Y, setting the thickness variation rate Z = ΔY / _{Y a.} The film thickness variation rate Z is normally determined according to the coating method, and is substantially constant regardless of the target film thickness.

4). Setting of calculation formulas for color coordinate values B1 and B2 and colorant concentration X Even if the film thickness of the second base coating film 5 varies, the color coordinate value N of the obtained multilayer coating film 2 is the upper limit of the target color coordinate value. It is necessary not to exceed TH and not to fall below the lower limit TL. Therefore, as shown in FIG. 5, when the target film thickness of the second base coating film 5 is Yt, the color coordinate value N of the laminated coating film 2 is the target at the lower limit value Yt (1-Z) of the target film thickness Yt. It is assumed that the color coordinate value becomes the lower limit TL, and the upper limit value Yt (1 + Z) becomes the upper limit TH of the target color coordinate value. That is, when the upper limit TH, the lower limit TL, and the film thickness variation rate Z are given to the model formula (1), the following formulas (2) and (3) are obtained.

TL = P− (P−B1) × exp {−AXY (1-Z)} (2)
TH = P− (P−B1) × exp {−AXY (1 + Z)} (3)

  Solving the simultaneous equations of equations (2) and (3) with respect to B1, the following equation (4) is obtained, and the color coordinate value B1 of the first base coating film 4 is P value, TL value, TH value and Z value. Obtained from

(P-TL) / (P-B1) = exp {-AXY (1-Z)}
(P-TH) / (P-B1) = exp {-AXY (1 + Z)}
ln {(P-TL) / (P-B1)} =-AXY (1-Z)
ln {(P-TH) / (P-B1)} =-AXY (1 + Z)
(P-TL) ^{1 + Z} / (P-TH) ^1-Z = (P-B1) ^2Z
B1 = P-{(P-TL) ^{1 + Z} / (P-TH) ^1-Z } ^{1 / 2Z} (4)

  Solving the simultaneous equations of equations (2) and (3) with respect to AXY, the following equation (5) is obtained, and the following equation (5) is obtained, and the colorant concentration X of the second base coating film 5 is P value. , TL value, TH value, Z value, coloring power A of the colorant, and target film thickness Yt.

(P-TL) / (P-TH) = (P-B1) exp {-AXY (1-Z)} / (P-B1) exp {-AXY (1 + Z)}
= {Exp (AXYZ)} ²
AXY = (1 / 2Z) · ln {(P-TL) / (P-TH)} (5)

  The color coordinate value B2 of the second base coating film 5 can be expressed by the following equation (6) from the model equation (1).

    B2 = (P−B1) {1-exp (−AXY)} (6)

  As described above, in order to set the color coordinate values B1 and B2 and the colorant concentration X, it is necessary to obtain the color coordinate value P and the colorant coloring power A at which 100% concealment is obtained.

5. Determination of color coordinate value P and colorant coloring power A at which 100% concealment is obtained
[Measurement of color coordinate values]
On the first base coating film 4 having a pigment concentration of 1% was prepared by the same coating method Sample pigment concentration and film thickness formed by laminating a second base coating film 5 of the different Do that several. As the pigment for the first base coating film 4 and the second base coating film 5, red was adopted. The pigment concentration of the second base coating film 5 was two types of 1% and 2%, and the film thickness was changed in the range of 6 to 24 μm. Then, each value of L coordinate, a coordinate and b coordinate in the Lab color system of the coating color of the laminated coating film of each sample was measured with a spectrophotometer MA68II manufactured by X-Rite at a reflection angle of 15 °. The results are shown in Table 1 and FIGS.

  According to FIGS. 6 to 8, since the pigment used in the experiment has a characteristic that the degree of absorption of the L coordinate axis changes, the following description will be made by adopting the L coordinate value as the color coordinate value.

[Fitting of measured data to model formula]
The colorimeter detects and quantifies the amount of light absorbed by the sample from white light. Therefore, in order to fit the L coordinate value obtained by this colorimeter to the coloring model equation (1), a conversion of “L ← 100−L” is performed. The results are as shown in Table 2 and FIG.

  The graph of FIG. 9 was extrapolated linearly to obtain an L coordinate value P = 63 at which 100% concealment was obtained, and an L coordinate value B1 = 35 of the first base coating film 4.

  On the other hand, the following equation (7) is obtained from the model equation (1).

exp (-AXY) = (PL) / (P-B1)
AXY = −ln {(PL) / (P−B1)} (7)

  An AXY value was obtained by substituting P = 63, B1 = 35, and the converted color coordinate value L in Table 2 into Equation (7). The results are shown in Table 3 and FIG.

  According to FIG. 10, the AXY value increases linearly (substantially in proportion) with an increase in the film thickness of the second base coating film 5, and the AXY value represents the coloring power of the coating film. Recognize.

  In the following, for the sake of simplicity, the description will be continued only for the case of a pigment concentration of 2%. The AXY value in Table 3 is divided by the film thickness Y to be converted into a value AX per unit film thickness. The results are shown in Table 4.

  The AX value in Table 4 was divided by the pigment concentration X (mass fraction 0.02), and the average was obtained to obtain the pigment coloring power A = 4.342.

6). Comparison of Measured Value and Theoretical Value for L Coordinate Value Using P = 63, B1 = 35 and A = 4.342 obtained in 5 above, and pigment concentration X (mass fraction 0.02), model equation (1 ) To determine the L coordinate value (theoretical value) of the laminated coating film. The results are shown in Table 5 and FIG. Note that the L coordinate value (theoretical value) is converted again to “L ← 100−L” with respect to the calculated value based on the model equation (1) in order to correspond to the actually measured value.

  In FIG. 11, each plot shows an actual measurement value, and a characteristic line L shows a theoretical value. According to the figure, it can be seen that the theoretical values are in good agreement with the measured values.

7). Setting of B1, B2 and pigment concentration X according to film thickness variation rate Z The upper limit of the target L coordinate value of the laminated coating film 2 is set to TH = 45, the lower limit thereof is set to TL = 40, and the result of FIG. Based on this, assuming that P = 63 and A = 4.342, B1 with respect to the film thickness variation rate Z is obtained by the equation (4), and B2 with respect to the film thickness variation rate Z is obtained by the equations (5) and (6).

B1 = P-{(P-TL) ^{1 + Z} / (P-TH) ^1-Z } ^{1 / 2Z} (4)
AXY = (1 / 2Z) · ln {(P-TL) / (P-TH)} (5)
B2 = (P−B1) {1-exp (−AXY)} (6)

  The results are shown in FIG. When the target film thickness Yt of the second base coating film 5 is 12 μm and the film thickness variation is 12 ± 2 μm, the film thickness variation rate is Z = 0.167. In this case, when Z = 0.167, B1 = 21.16, B2 = 2.49, and AXY = 0.7209. Since A = 4.342 and the target film thickness Yt = 12 μm, the target pigment concentration X is 0.01387 (about 1.4%) in mass fraction.

  When the upper limit of the target L coordinate value of the laminated coating film 2 is set to TH = 43 and the lower limit thereof is set to TL = 40, the fluctuation characteristics of B1 and B2 with respect to the film thickness fluctuation rate Z are as shown in the graph of FIG. In this case, when the film thickness variation rate is Z = 0.167, B1 = 30.65, B2 = 10.90, and AXY = 0.4111. Since A = 4.342 and the target film thickness Yt = 12 μm, the target pigment concentration X in this case is 0.0078893 (about 0.8%) in mass fraction.

  As in the latter case, when the width between the upper limit TH and the lower limit TL of the target color coordinate value of the laminated coating film 2 is narrow, the requirement for limiting the coating color variation on the second base coating film 5 becomes severe. In this regard, according to the present invention, as described above, as the width between the upper limit TH and the lower limit TL becomes narrower, B1 of the first base coating film 4 becomes larger (the coating color becomes darker), and the second base coating is performed. Since B2 of the film 5 becomes small (the pigment concentration X becomes low and the coating color becomes light), the effect of being able to automatically meet the restriction request is obtained.

  As described above, the above embodiment is merely an example of the present invention, and depending on the type of pigment, the color of the a-axis or b-axis or the three-dimensional color coordinate value of the laminated coating film Specifications can be set, and the present invention can also be applied to other color systems such as XYZ and RGB. Moreover, also when employ | adopting dye as a coloring agent, the specification of a laminated coating film can be set according to the said embodiment.

  Moreover, although the said embodiment is a case which laminated | stacked the 2nd base coating film directly on the surface of the 1st base coating film, a transparent clear coating film intervenes between a 1st base coating film and a 2nd base coating film. Even in cases, the present invention is applicable.

1 Body (steel plate)
2 Laminated coating 3 Electrodeposition coating 4 First base coating (metallic base coating)
5 Second base coating 6 Clear coating 7 Bright material 8 Pigment 9 Intermediate coating

Claims (4)

A first base coating film containing a pigment or a dye as a colorant and concealing the underlayer, and a second base laminated on the upper side of the first base coating film and containing a pigment or a dye as a colorant and having visible light transmittance A method of setting specifications for the color development in a multilayer coating film designed to develop a specific color depending on the coating film,
Setting a model that expresses the coating color of the laminated coating film as a color coordinate value N on a color space that changes exponentially with the colorant concentration X and the film thickness Y of the second base coating film as variables;
Setting an upper limit TH and a lower limit TL of target color coordinate values for causing the specific color to be developed by the laminated coating film;
Setting a target film thickness Yt during actual coating of the second base coating film and a film thickness variation rate Z based on the target film thickness Yt;
Based on the model, when the film thickness Y of the second base coating film is the lower limit value of the film thickness fluctuation range, the color coordinate value N becomes the lower limit TL of the target color coordinate value, and the second base coating film The first base corresponding to the film thickness variation rate Z under the condition that the color coordinate value N is the upper limit TH of the target color coordinate value when the film thickness Y is the upper limit value of the film thickness variation width. A step of setting a color coordinate value B1 of the coating film and a colorant concentration X of the second base coating film. In claim 1,
In the step of setting the model, the following coloring model formula (1) expressing the coating color of the laminated coating film by the color coordinate value N in the color space is set:
N = P− (P−B1) × exp (−AXY) (1)
(Where P is a color coordinate value at which 100% concealment is obtained in the color space, X is the colorant concentration (mass fraction) of the second base coating film, and Y is the film thickness (μm of the second base coating film). ), A is the colorant obtained by substituting the measured N value, P value, B1 value, X value, and Y value for the laminated coating film sample prepared using the colorant into the model equation (1). The coloring power of
When the film thickness of the second base coating film is Yt (1 + Z), the color coordinate value N is the upper limit TH of the target color coordinate value, and the film thickness of the second base coating film is Yt (1-Z). Of the first base coating film according to the film thickness variation rate Z based on the model equation (1) under the condition that the color coordinate value N is the lower limit TL of the target color coordinate value. A method for setting the specifications of the laminated coating film, wherein the color coordinate value B1 and the colorant concentration X of the second base coating film are set. In claim 1 or claim 2,
The first base coating film is a metallic base coating film containing the colorant and brilliant material. In any one of Claim 1 thru | or 3,
The second base coating film has a light transmittance of 55% or more for the specific color. The hue of the specific color is set to the median value of the Munsell hue ring. When the hue range is -25 or more and +25 or less when the hue range is displayed as the hue range of the specific color, the average light transmittance in the wavelength region outside this hue range is 50% or less. The original setting method.

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