Calculation method and manufacturing method for paint composition

Abstract

To provide a calculation method and manufacturing method for paint that can perform computer color matching regardless of the type of color measurement device.SOLUTION: The calculation method of the present invention comprises a process of converting the direct-reading method of tristimulus values to the spectral colorimetry method, which is used for computer color matching.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a calculation method (particularly a method for calculating spectral reflectance) and a method for manufacturing a paint composition.

Background Art

[0002] Paint manufacturers adjust the color of paint compositions to achieve a target paint color. Customers who use them manage the paint compositions based on the color difference measured with a color difference meter. The color difference meters are roughly classified into two types: a tristimulus value direct-reading color measuring device that directly measures three stimulus values that are the basis of color, by the stimulus value direct-reading method, and a spectral color measuring device that measures spectral reflectance (transmittance) and calculates the three stimulus values therefrom by calculation. Paint manufacturers and customers use one of these devices.

[0003] It is well known that the value of the measured color difference changes depending on the color difference meter. In recent years, as the demand for color adjustment accuracy has increased, the difference in the color difference value due to the difference in color difference meters cannot usually be ignored. For this reason, paint manufacturers perform color adjustment using the color difference meter specified by the customer.

[0004] Here, as a color adjustment method by paint manufacturers, computer color matching (CCM) using a computer is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Computer color matching is performed using spectral reflection data indicating the relationship between wavelength and spectral reflectance. In a spectral colorimeter, when measuring color difference, the color difference is measured from the spectral reflectance at each wavelength. Therefore, if the color difference is measured, the spectral reflection data used for computer color matching can be obtained. However, in a tristimulus value direct-reading colorimeter, spectral reflection data is not obtained when measuring color difference.

[0007] From this, when managing the color difference of a paint composition using a tristimulus value direct-reading colorimeter (for example, when a paint manufacturer adjusts to the customer), since spectral reflection data is not obtained, there has been a problem that computer color matching cannot be performed.

[0008] Therefore, an object of the present invention is to provide a calculation method and a method for manufacturing a paint that can perform computer color matching regardless of the type of colorimeter.

Means for Solving the Problems

[0009] The gist configuration of the present invention is as follows. (1) A step of converting the tristimulus value direct-reading method into a spectral colorimetry method, A calculation method characterized by being used for computer color matching using a computer.

[0010] (2) A first acquisition step of acquiring first spectral reflection data of a first paint film obtained from a paint composition composed of primary color pigments using a spectral colorimeter, wherein the first spectral reflection data is data indicating the relationship between wavelength and spectral reflectance, A second acquisition step of acquiring the color values of the primary color pigments of the color of a second paint film obtained from a paint composition composed of primary color pigments using a tristimulus value direct-reading colorimeter, A first calculation step of calculating a provisional blending of primary color pigments such that the color value measured using the spectral colorimeter corresponds to the color value acquired in the second acquisition step using the first spectral reflection data acquired in the first acquisition step by a first calculation unit. A second calculation step of calculating second spectral reflectance data of each primary color colorant of the color of the coating film obtained using the provisional formulation using the first spectral reflectance data obtained in the first acquisition step, wherein the second spectral reflectance data is data indicating the relationship between wavelength and spectral reflectance; and a spectral reflectance calculation method characterized by including the above.

[0011] (3) Further including a coefficient calculation step of calculating an absorption coefficient K and a scattering coefficient S of each primary color colorant based on the first spectral reflectance data obtained in the first acquisition step. In the first calculation step, the provisional formulation of the primary color colorant is calculated using the absorption coefficient K and the scattering coefficient S calculated in the coefficient calculation step, and the spectral reflectance calculation method according to (2) above.

[0012] (4) The second calculation step Based on the provisional formulation calculated in the first calculation step and the absorption coefficient K and the scattering coefficient S of each primary color colorant calculated in the coefficient calculation step, a coefficient ratio calculation step of calculating a coefficient ratio K / S corresponding to the provisional formulation; and a second spectral reflectance calculation step of calculating the second spectral reflectance data from the calculated coefficient ratio K / S, and the spectral reflectance calculation method according to (3) above.

[0013] (5) In the first calculation step, the calculation is performed using a mathematical optimization method or a brute force search method, and the spectral reflectance calculation method according to any one of (2) to (4) above.

[0014] (6) The first coating film and the second coating film are the same coating film, and the spectral reflectance calculation method according to any one of (2) to (5) above.

[0015] (7) The first coating film and the second coating film are different coating films, and the spectral reflectance calculation method according to any one of (2) to (5) above, wherein the color difference ΔE between the first coating film and the second coating film is 2 or less.

[0016] ​​ (8) The method for calculating the spectral reflectance according to any one of (2) to (7) above, wherein the number of types of the first coating film is 10 or more.

[0017] (9) A method for manufacturing a coating composition, which calculates a formulation suitable for obtaining a coating composition having a desired coating property by computer color matching using a computer, and obtains a coating composition using the calculated formulation, A first acquisition step of acquiring first spectral reflection data of a first coating film obtained from a coating composition composed of primary color colorants using a spectrophotometric color measuring device, wherein the first spectral reflection data is data showing the relationship between wavelength and spectral reflectance; A second acquisition step of acquiring color values of each primary color colorant of the color of a second coating film obtained from a coating composition composed of primary color colorants using a tristimulus value direct reading type color measuring device; A first calculation step of calculating a provisional formulation of primary color colorants such that the color value measured using the spectrophotometric color measuring device corresponds to the color value obtained in the second acquisition step by using the first spectral reflection data acquired in the first acquisition step by a first calculation unit; A second calculation step of calculating second spectral reflection data of each primary color colorant of the color of a coating film obtained using the provisional formulation by using the first spectral reflection data acquired in the first acquisition step by a second calculation unit, wherein the second spectral reflection data is data showing the relationship between wavelength and spectral reflectance, and including: In the computer color matching, the method for manufacturing a coating composition is characterized in that the second spectral reflection data calculated in the second calculation step is used. [Advantages of the Invention]

[0018] According to the present invention, it is possible to provide a calculation method and a method for manufacturing a coating material capable of performing computer color matching regardless of the type of color measuring device. [Brief Description of the Drawings]

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be exemplified and described in detail with reference to the drawings.

[0021] <Calculation Method> The calculation method according to an embodiment of the present invention includes a step of converting the tristimulus value direct reading method into a spectrophotometric colorimetry method, and is used for computer color matching using a computer. According to the calculation method of the present embodiment, even when management is performed by the tristimulus value direct reading method, it can be converted into a spectrophotometric colorimetry method to obtain spectral reflectance data, so that computer color matching can be executed.

[0022] The tristimulus value direct reading method can use a tristimulus value direct reading type colorimeter, and the spectrophotometric colorimetry method can use a spectrophotometric colorimetry method.

[0023] <Method for Calculating Spectral Reflectance> Next, a method for calculating spectral reflectance according to an embodiment of the present invention will be exemplified and described. FIG. 1 is a flowchart of a method for calculating spectral reflectance according to an embodiment of the present invention.

[0024] As shown in FIG. 1, in the method for calculating the spectral reflectance of the present embodiment, first, using a spectrophotometric colorimeter, first spectral reflection data of a first coating film obtained from a paint composition composed of primary color pigments is acquired (first acquisition step: S101). FIG. 2 is a diagram for explaining colorimetry in the case of a spectrophotometric colorimeter. In FIG. 2, a coated board having three types of first coating films (see the left diagram in FIG. 2) respectively obtained from a paint composition composed of three types of primary color pigments (from the top: black pigment, yellow pigment, blue pigment) is exemplified. According to colorimetry using a spectrophotometric colorimeter (see the middle diagram in FIG. 2), first spectral reflection data (see the right diagram in FIG. 2), which is data showing the relationship between wavelength and spectral reflectance, can be obtained. Such first spectral reflection data is acquired for each primary color pigment. FIG. 3 (upper diagram) shows an example of the first spectral reflection data. As also exemplified in FIG. 3, the first spectral reflection data may be data of a single primary color pigment, or may be data of a mixture of a primary color pigment with a white pigment or a black pigment.

[0025] Next, using a tristimulus value direct-reading colorimeter, color values of each primary color pigment of the color of a second coating film obtained from a paint composition composed of primary color pigments are acquired (second acquisition step: S102). FIG. 4 is a diagram for explaining colorimetry in the case of a tristimulus value direct-reading colorimeter. In FIG. 4, a coated board having a second coating film (see the left diagram in FIG. 4) obtained from a paint composition composed of one type of primary color pigment (green pigment) is exemplified. In colorimetry using a tristimulus value direct-reading colorimeter (see the middle diagram in FIG. 4), spectral reflection data cannot be obtained (see the right diagram in FIG. 4).

[0026] Here, the first coating film (used in the first acquisition step) and the second coating film (used in the second acquisition step) are preferably the same coating film. This is because the reproducibility of the spectral reflectance can be improved.

[0027] Alternatively, the first coating film and the second coating film are different coating films, and it is also preferable that the color difference ΔE between the first coating film and the second coating film is 2 or less. This is because by making the coating films have as close colors as possible, the accuracy of calculating the provisional formulation described later can be improved.

[0028] Also, it is preferable that the number of types of the first coating film is 10 or more. This is because the accuracy of the calculation of the provisional formulation described later can be improved.

[0029] Next, the first calculation unit calculates a provisional formulation of the primary color colorants such that the color value measured using the spectroscopic colorimeter corresponds to the color value obtained in the second acquisition step, using the first spectroscopic reflection data acquired in the first acquisition step (first calculation step: S103). The first calculation unit can be an arbitrary known computer or the like.

[0030] As shown in FIG. 3, by acquiring the first spectroscopic reflection data, color values (for example, L * a * b * values and XYZ values) can be calculated. As a more specific process, prior to the first calculation step (S103), after the first acquisition step (S101), based on the first spectroscopic reflection data acquired in the first acquisition step (S101), it is preferable to further include a coefficient calculation step of calculating the absorption coefficient K and the scattering coefficient S of each primary color colorant. Thereby, the above-described calculation becomes possible. The coefficient calculation step may be performed before or after the second acquisition step (S102). The coefficient calculation step can be executed, for example, by calculation based on the Kubelka-Munk theory.

[0031] FIG. 5 is a diagram for explaining the calculation of the provisional formulation of the primary color colorants. In the first calculation step (S103), for example, a provisional formulation of the primary color colorants corresponding to the color value (of the green colorant) obtained in the second acquisition step (S102) is calculated based on the first spectroscopic reflection data in the case of the spectroscopic colorimeter. That is, in this example, based on the first spectroscopic reflection data in the case of the spectroscopic colorimeter (see FIG. 3), it is calculated that the provisional formulation corresponding to the color value of the green colorant in the tristimulus value direct-reading colorimeter is 7% of the black colorant, 55% of the yellow colorant, and 38% of the blue colorant (see FIG. 5. In FIG. 5, the blending amount (colorant blending ratio) is schematically shown by the vertical width of each color.).

[0032] As a specific calculation, in the first calculation step (S103), it is preferable to calculate the provisional blending of the primary color colorants using the absorption coefficient K and the scattering coefficient S calculated in the coefficient calculation step. Although this calculation is not particularly limited, it can be executed using a mathematical optimization method.

[0033] Also, in the first calculation step (S103), it is preferable to perform the calculation using a mathematical optimization method or a brute-force search method.

[0034] Next, the second calculation unit calculates the second spectral reflectance data of each primary color colorant of the color of the coating film obtained using the provisional blending, using the first spectral reflectance data obtained in the first acquisition step (S101) (second calculation step: S104). The second spectral reflectance data is also data showing the relationship between the wavelength and the spectral reflectance. The second calculation unit can be an arbitrary known computer or the like.

[0035] That is, since the provisional blending calculated in the first calculation step (S103) is for the case of a spectral colorimeter, by using the first spectral reflectance data obtained in the first acquisition step (S101) (in this example, by using the first spectral reflectance data of the black colorant, yellow colorant, and blue colorant constituting the provisional blending), the second spectral reflectance data of each primary color colorant (in this example, the green colorant by the provisional blending of the black colorant, yellow colorant, and blue colorant) of the color of the coating film obtained using the provisional blending can be calculated (see the right figure in FIG. 5).

[0036] The second spectral reflectance data obtained in this way can be regarded as the spectral reflectance data of each primary color colorant measured using a tristimulus value direct-reading colorimeter. Thereby, for example, regarding the coating film obtained from a paint composition in which each primary color colorant is mixed, it becomes possible to calculate the blending and color when using a tristimulus value direct-reading colorimeter.

[0037] As a specific calculation, the second calculation step (S104) includes a coefficient ratio calculation step of calculating a coefficient ratio K / S corresponding to the provisional formulation based on the provisional formulation calculated in the first calculation step (S103) and the absorption coefficient K and scattering coefficient S of each primary color colorant calculated in the coefficient calculation step, and a second spectral reflectance data calculation step of calculating second spectral reflectance data from the calculated coefficient ratio K / S, which is preferable.

[0038] The coefficient ratio calculation step can be executed by calculation using, for example, Duncan's color mixing formula. Further, the second spectral reflectance data calculation step can be executed by calculation based on, for example, the Kubelka-Munk theory.

[0039] As described above, according to the method for calculating the spectral reflectance of the present embodiment, even when management is performed by the tristimulus value direct reading method, the spectral reflectance data (second spectral reflectance data) in the tristimulus value direct reading method is calculated, and the spectral reflectance data can be regarded as the spectral reflectance data of each primary color colorant measured using a tristimulus value direct reading type color measuring device. Therefore, by using the spectral reflectance data, computer color matching can be executed regardless of the type of color measuring device.

[0040] FIG. 6 is a diagram for explaining a method for calculating the spectral reflectance according to an embodiment of the present invention. In the example of FIG. 6, regarding the second coating film, not only the color values are obtained using a tristimulus value direct reading type color measuring device, but also the color values are obtained in advance by a spectral type color measuring device. This may be performed before the first calculation step. Then, in the first calculation step, when calculating the provisional formulation, the provisional formulation is a mixture obtained by adding a black colorant and / or a white colorant (only) to the primary color colorant (green colorant in this example) corresponding to the color value obtained by the spectral type color measuring device obtained in advance. In this example, it is 1% black colorant, 1% white colorant, and 98% green colorant. According to this method, since the reproducibility of the color values using the provisional formulation in the case of the spectral type color measuring device is more reliable, more accurate second spectral reflectance data can be obtained. Thereby, the accuracy of computer color matching can also be improved.

[0041] <Method for Manufacturing a Paint Composition> Next, a method for manufacturing a paint according to an embodiment of the present invention will be exemplified and described. The method for manufacturing a paint composition according to an embodiment of the present invention is a method for manufacturing a paint composition, which calculates a formulation suitable for obtaining a paint composition having a desired paint property by computer color matching using a computer, and obtains a paint using the calculated formulation.

[0042] In the method for manufacturing a paint composition of the present embodiment, first, using a spectrophotometric colorimeter, first spectral reflection data of a first paint film obtained from a paint composition composed of primary color colorants is acquired. Since this step is the same as the "first acquisition step" in the embodiment of the method for calculating spectral reflectance, a repeated description will be omitted.

[0043] Next, using a tristimulus value direct-reading colorimeter, color values of each primary color colorant of the color of a second paint film obtained from a paint composition composed of primary color colorants are acquired. Since this step is the same as the "second acquisition step" in the embodiment of the method for calculating spectral reflectance, a repeated description will be omitted.

[0044] Next, the first calculation unit calculates a provisional formulation of the primary color colorants such that the color values measured using the spectrophotometric colorimeter using the first spectral reflection data acquired in the first acquisition step correspond to the color values acquired in the second acquisition step. Since this step is the same as the "first calculation step" in the embodiment of the method for calculating spectral reflectance, a repeated description will be omitted.

[0045] Next, the second calculation unit calculates second spectral reflection data of each primary color colorant of the color of the paint film obtained using the provisional formulation using the first spectral reflection data acquired in the first acquisition step. Since this step is the same as the "second calculation step" in the embodiment of the method for calculating spectral reflectance, a repeated description will be omitted.

[0046] Next, in computer color matching, the second spectral reflection data calculated in the second calculation step is used. According to the method for manufacturing the coating composition of the present embodiment, even when management is performed by the tristimulus value direct reading method, similar to that described in the embodiment of the method for calculating the spectral reflectance, spectral reflectance data (second spectral reflectance data) by the tristimulus value direct reading method is calculated, and the spectral reflectance data can be regarded as the spectral reflectance data of each primary colorant measured using a tristimulus value direct reading type colorimeter. Therefore, by using the spectral reflectance data, computer color matching can be performed regardless of the type of colorimeter.

[0047] In this specification, the color value is, for example, L * a * b * value in the color space of L * value, a * value, b * value (JIS Z8781-4 (2013)), X-Y-Z color system, R-G-B color system, Yxy color system, Hunter L-a-b color system, L * -C * -h * color systems such as color systems based on the color system can be used. The color value can be measured using a known color measurement method. As an example, when using CM-512m3 commercially available from Konica Minolta Co., Ltd. and setting the light receiving part perpendicular to the coating film to 0°, the L * value, a * value, b * value can be measured. Alternatively, it can be measured using X-Rite MA68II (manufactured by X-Rite). The measurement angle can be appropriately adjusted according to the purpose or the device to be used. Any other arbitrary index can be used. Further, for example, reflection spectrum data, an arbitrary index such as an index with the reflection spectrum intensity every 5 nm from 380 nm to 780 nm regarded as the color, can also be used.

[0048] In another aspect, instead of calculating the provisional color mixture of the primary colors, the first calculation step (S103) may be performed by adding a correction function. That is, in another aspect, the first calculation step is performed by the first calculation unit using the first spectral reflectance data acquired in the first acquisition step, such that the color value measured using the spectral colorimeter corresponds to the color value acquired in the second acquisition step. A correction function is added to the first spectral reflectance data and calculated. That is, the correction function is a function indicating the difference between the second spectral reflectance data and the first spectral reflectance data. By adding the correction function to the first spectral reflectance data, the second spectral reflectance data is obtained. And, in another aspect, the second calculation step is a step of calculating, by the second calculation unit, the second spectral reflectance data of each primary color of the color of the coating film obtained using the correction function, using the first spectral reflectance data acquired in the first acquisition step. The second spectral reflectance data is data indicating the relationship between the wavelength and the spectral reflectance.

Example

[0049] [[(A) Preliminary preparation]] First, the method for preparing the colorants used in the examples will be described. <(a1) Preparation example of white colorant> 55 parts by mass of polyester resin (A) as a resin, 12 parts by mass of Super Bekamin L-155-70 as a crosslinking agent, 8 parts by mass of T-SOL 150 as organic solvent 1, 7 parts by mass of cyclohexanone as organic solvent 2, and 18 parts by mass of Taypeak CR-97 as a white pigment were mixed, and using a sand mill (dispersion medium: glass beads), dispersion was carried out until the maximum particle diameter of the pigment coarse particles became 10 μm or less, and a white colorant was prepared.

[0050] <(a2) Preparation example of other colorants> Except for changing each material type and amount as shown in Table 1 below, black and green colorants were prepared in the same manner as the preparation example of the white colorant. The formulations of the respective colorants are shown in Table 1.

[0051]

Table 1

[0052] <(a3) Coating film preparation method> <Preparation example of coating composition W for calculation> 100 parts by mass of the white colorant and 3 parts by mass of Disparon OX-70 as a surface conditioner were added, and they were uniformly mixed using a disperser to prepare a coating composition W for calculation.

[0053] <Preparation examples of other coating compositions for calculation> Except for changing the types and amounts of each material as shown in Table 2 below, they were prepared in the same manner as the preparation example of the coating composition W for calculation to obtain coating compositions K, G for calculation, and mixed coating composition W-K, W-G for calculation. The formulations of the respective coating compositions for calculation are shown in Table 2.

[0054]

Table 2

[0055] Method for preparing polyester resin (A) Into a reaction vessel equipped with a thermometer, a condenser and a stirrer, 155 parts by mass of neopentyl glycol, 222 parts by mass of 1,6-hexanediol, 50 parts by mass of trimethylolpropane, 441 parts by mass of isophthalic acid, 132 parts by mass of adipic acid and 26 parts by mass of xylene were mixed, and the temperature was gradually raised to 230 °C in a nitrogen stream, and while distilling off the generated water, the esterification reaction was carried out until the dehydration amount reached 126 parts by mass and the reactant reached a predetermined viscosity. Then, after lowering the temperature of the reaction vessel to 50 °C, 90 parts by mass of xylene, 379 parts by mass of T-SOL 150 and 87 parts by mass of propylene glycol monomethyl ether acetate were mixed to prepare a coating film-forming resin (A) (polyester resin; solid content concentration: 60% by mass, number average molecular weight: 3,000, hydroxyl value: 55 mgKOH / g).

[0056] Details of the materials used in the preparation of the coating composition are as follows. · Crosslinking agent: Super Bekamin L-155-70 (manufactured by DIC Corporation), butylated melamine resin; Solids concentration: 70% by mass · Surface conditioner: Disparon OX-70 (manufactured by Kusumoto Chemicals, Ltd.), acrylic-based surface conditioner; Solids concentration: 30% by mass · White pigment: Taypeak CR-97 (manufactured by Ishihara Sangyo Co., Ltd.), titanium dioxide · Black pigment: Black 6350 (manufactured by Asahi Kasei Chemicals Corporation), chromium iron oxide · Green pigment: Lionol Green 6YKP-N (manufactured by Toyo Color Co., Ltd.), brominated copper phthalocyanine · Yellow pigment: Tarox Synthetic Iron Oxide HY-100 (manufactured by Titanium Industry Co., Ltd.), yellow iron oxide · Red pigment: Toda Color KN-V (manufactured by Toda Pigment Co., Ltd.), ferric oxide · Organic solvent 1: T-SOL 150 (manufactured by JXTG Energy Corporation), aromatic solvent · Organic solvent 2: Cyclohexanone (manufactured by Shoei Chemical Industry Co., Ltd.), ketone solvent

[0057] <Method for preparing coating film W for calculation> On the surface of the substrate (zinc-aluminum alloy plated steel sheet: 1,800 × 300 × 0.35 mm), as an undercoat paint, Fine Tough G Primer (epoxy resin-based primer: manufactured by Nippon Paint Industrial Coatings Co., Ltd.) was applied by roll coater (reference film thickness: 5 μm), and then baked for 60 seconds under the condition that the maximum temperature reached by the material was 210 °C to form an undercoat film. Next, the coating composition W for calculation was applied on the above undercoat film by roll coater (reference film thickness: 15 μm), and then baked for 60 seconds under the condition that the maximum temperature reached by the material was 250 °C, and then immediately cooled to obtain a coating film of the coating composition W for calculation (coating film W for calculation).

[0058] Coating films K, G, Y, R, B for calculation and mixed coating films W-K, W-G, W-Y, W-R, W-B for calculation were obtained in the same manner as the method for preparing the coating film W for calculation.

[0059] <Obtaining process> [[(B) First obtaining process]] The first spectral reflectance data of the first coating film obtained in the first acquisition step was measured by the following method.

[0060] Measurement of spectral reflectance data Regarding the various coating films for calculation (W, K, G, Y, R, B, W-K, W-G, W-Y, W-R, W-B) obtained above, using a spectral colorimeter SE7700 (manufactured by Nippon Denshoku Industries Co., Ltd.), which is a spectral type color measuring device, the relationship between the wavelength and the spectral reflectance was determined.

[0061] [[(C) Second acquisition step]] The color values of the second coating film obtained in the second acquisition step were measured by the following method.

[0062] Measurement of color values Regarding the various coating films for calculation (W, K, G, Y, R, B, W-K, W-G, W-Y, W-R, W-B) obtained above, using a colorimeter SM-T (manufactured by Suga Test Instruments Co., Ltd.), which is a tristimulus value direct reading type color measuring device, the color (L * , a * , b * values) was measured.

[0063] [[(D) Coefficient calculation step]] Based on the relationship between the wavelength and the spectral reflectance of the coating film W for calculation obtained above, the absorption coefficient K and the scattering coefficient S of the coating film W for calculation were calculated respectively. Based on the relationship between the wavelength and the spectral reflectance of the coating films W, K and W-K for calculation obtained above, the absorption coefficient K and the scattering coefficient S of the coating film K for calculation were calculated respectively. Similarly, based on the relationship between the spectral reflectance of the coating films W, G and W-G for calculation obtained above, the absorption coefficient K and the scattering coefficient S of the coating film G for calculation were calculated respectively. Similarly, based on the relationship between the spectral reflectance of the coating films W, Y and W-Y for calculation obtained above, the absorption coefficient K and the scattering coefficient S of the coating film Y for calculation were calculated respectively. Similarly, based on the relationship between the spectral reflectance of the coating films W, R and W-R for calculation obtained above, the absorption coefficient K and the scattering coefficient S of the coating film R for calculation were calculated respectively. Similarly, from the relationship between the spectral reflectances of the calculation coatings W, B, and W-B obtained above, the absorption coefficient K and scattering coefficient S of the calculation coating B were calculated respectively. Also, the coefficient k1 of the Sanderson correction formula was set to 0.04 and k2 to 0.57. Table 3 shows the absorption coefficient K and scattering coefficient S calculated for each calculation coating.

[0064]

Table 3

[0065] <Calculation step> [[(E) First calculation step]] <Prediction step of provisional mixing composition corresponding to paint properties> Example 1 Taking the paint properties measured by the colorimeter SM-T, which is a tristimulus value direct-reading color measuring device, as the target values, and using the absorption coefficient K and scattering coefficient S of the calculation paint composition W, the calculation paint composition K, and the calculation paint composition G, the provisional mixing of the paint composition G corresponding to the paint properties was calculated by mathematical optimization. The results of the provisional mixing of the calculated paint composition G are shown in Table 4. Also, for the paint composition G, the paint properties measured by the colorimeter SM-T, the paint properties measured by the spectrocolorimeter SE7700, and the color difference (ΔE * ) from the measurement results of the colorimeter SM-T are shown in Table 5.

[0066] [[(F) Second calculation step]] <(f1) Coefficient ratio calculation step> Using Duncan's theoretical formula, the K / S of the paint composition G was calculated from the provisional mixing of the paint composition G. <(f2) Second spectral reflectance data calculation step> Using Kubelka-Munk's theory and the Sanderson correction formula, the spectral reflectance of the paint composition G was calculated from the K / S of the paint composition G. Also, the coefficients k1 and k2 of the Sanderson correction formula were adopted as the same numerical values as above. The calculation results are shown in Table 6. <(f3) Paint properties and ΔE * Calculation step> The color difference (ΔE * ) between the paint properties calculated from the spectral reflectance calculated from the temporary formulation and the measurement results of the colorimeter SM-T was calculated. For the paint composition G, the paint properties measured with the colorimeter SM-T, the color difference (ΔE * ) between the paint properties measured with the spectral colorimeter SE7700 and the measurement results of the colorimeter SM-T, and the color difference (ΔE * ) between the paint properties calculated from the spectral reflectance calculated from the temporary formulation and the measurement results of the colorimeter SM-T are shown in Table 7.

[0067] Example 2 Calculation was performed in the same manner as the calculation method of Example 1, except that the calculation target coating film G was changed to the calculation target coating film Y. Example 3 Calculation was performed in the same manner as the calculation method of Example 1, except that the calculation target coating film G was changed to the calculation target coating film R.

[0068]

Table 4

[0069]

Table 5

[0070]

Table 6

[0071]

Table 7

[0072] [[(G) Results]] As shown in Table 6, in any of the inventive examples, the second spectral reflection data of each primary color pigment of the color of the coating film obtained using the temporary formulation could be calculated. Also, as shown in Table 7, in any of the examples, ΔE that was 5 or more *It was possible to make it 0.3 or less. In the inventive example, it was possible to convert the three-stimulus value direct reading method into a spectroscopic colorimetry method.

Claims

1. including a step of converting a trichromatic value direct reading method into a spectrophotometric method, A calculation method characterized by being used for computer color matching using a computer.

2. A first acquisition step of acquiring first spectral reflection data of a first coating film obtained from a paint composition composed of primary color pigments using a spectrophotometric color measuring device, wherein the first spectral reflection data is data showing the relationship between wavelength and spectral reflectance; A second acquisition step of acquiring the color values of the primary color pigments of the color of a second coating film obtained from a paint composition composed of primary color pigments using a trichromatic value direct reading type color measuring device; A first calculation step of calculating a provisional blending of the primary color pigments such that the color value measured using the spectrophotometric color measuring device corresponds to the color value acquired in the second acquisition step by using the first spectral reflection data acquired in the first acquisition step by a first calculation unit; A second calculation step of calculating second spectral reflection data of the primary color pigments of the color of the coating film obtained using the provisional blending by using the first spectral reflection data acquired in the first acquisition step by a second calculation unit, wherein the second spectral reflection data is data showing the relationship between wavelength and spectral reflectance, and a method for calculating spectral reflectance, characterized by including the above steps.

3. Further including a coefficient calculation step of calculating an absorption coefficient K and a scattering coefficient S of each primary color pigment based on the first spectral reflection data acquired in the first acquisition step; The method for calculating spectral reflectance according to claim 2, wherein in the first calculation step, the provisional blending of the primary color pigments is calculated by using the absorption coefficient K and the scattering coefficient S calculated in the coefficient calculation step.

4. The second calculation step includes: A coefficient ratio calculation step of calculating a coefficient ratio K / S corresponding to the provisional blending based on the provisional blending calculated in the first calculation step and the absorption coefficient K and the scattering coefficient S of each primary color pigment calculated in the coefficient calculation step; A second spectral reflectance data calculation step of calculating the second spectral reflectance data from the calculated coefficient ratio K / S, and the method for calculating spectral reflectance according to claim 3, comprising the same.

5. In the first calculation step, the calculation is performed using a mathematical optimization method or a brute force search method, and the method for calculating spectral reflectance according to claim 2 or 3.

6. The first coating film and the second coating film are the same coating film, and the method for calculating spectral reflectance according to claim 2 or 3.

7. The first coating film and the second coating film are different coating films, The color difference ΔE between the first coating film and the second coating film is 2 or less, and the method for calculating spectral reflectance according to claim 2 or 3.

8. The number of types of the first coating film is 10 or more, and the method for calculating spectral reflectance according to claim 2 or 3.

9. A method for manufacturing a paint composition, which calculates a formulation suitable for obtaining a paint composition having a desired paint property by computer color matching using a computer, and obtains a paint composition using the calculated formulation, A first acquisition step of acquiring first spectral reflectance data of a first coating film obtained from a paint composition composed of primary color colorants using a spectrophotometric colorimeter, wherein the first spectral reflectance data is data showing the relationship between wavelength and spectral reflectance, A second acquisition step of acquiring color values of each primary color colorant of the color of a second coating film obtained from a paint composition composed of primary color colorants using a tristimulus value direct-reading colorimeter, A first calculation step of calculating a provisional formulation of primary color colorants such that the color value measured using the spectrophotometric colorimeter corresponds to the color value acquired in the second acquisition step using the first spectral reflectance data acquired in the first acquisition step by a first calculation unit, A second calculation step, in which second spectral reflectance data of each primary color colorant of the color of the coating film obtained using the temporary formulation is calculated using the first spectral reflectance data obtained in the first acquisition step by the second calculation unit, wherein the second spectral reflectance data is data indicating the relationship between the wavelength and the spectral reflectance, and In the computer color matching, the second spectral reflectance data calculated in the second calculation step is used. A method for producing a coating composition, characterized by this.

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