Color mixing method for efficiently solving metamerism phenomenon of automobile coating

Abstract

The invention provides a toning method for efficiently solving the metamerism phenomenon of automobile paint. The color mixing method comprises the steps of determining an initial color paste formula and determining a target color paste formula. The unknown color paste combination color can be predicted through the established color database and the logic of color paste splitting, so that the initial color paste formula close to the target color palette color is efficiently obtained, and compared with a mode of directly obtaining the initial formula according to a conventional color matching method such as visual comparison and color matching experience, the accuracy is higher, and the color matching efficiency is higher. Besides, after the initial color paste formula is determined, various supplementary color pastes are continuously added to accurately adjust the color value, so that the finally obtained target color paste formula is closer to the color of a target color plate provided by a client, the metamerism phenomenon does not exist, and delta E obtained under a D65 light source, an A light source and an F11 light source is smaller than 0.5.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and specifically includes a color matching method for efficiently solving the metamerism phenomenon of automotive coatings. Background Art

[0002] Metamerism, simply speaking, means the same color but different spectral compositions. If two objects present the same color under one light source but different colors under another light source, it is the metamerism phenomenon. In the field of automotive paints, since color is one of the most important indicators of automotive paints, the metamerism phenomenon is the situation that color matching work least wants to encounter. If metamerism unfortunately occurs during the development of new automotive paint colors, it may mean the failure of development or a significant increase in workload.

[0003] In the development process of new automotive paint colors, generally, the customer provides a target color plate, and then the color matching personnel of the paint supplier design a formula. According to the customer's construction conditions, the paint formula consistent with the color of the target color plate is obtained by adjusting the pigment ratio. The target color plates provided by customers come from a wide range of sources, and the preparation of such color plates often does not consider the possibility of construction, only focusing on the color effect, and many pigments not allowed in automotive paints or even effect colors made by special process methods will be used; in another case, the customer may provide the standard plate of the vehicle body and require the paint supplier to develop the paint for supporting parts, and then the problem of different systems will be faced. The ultimate result of the above problems is that the types of pigments that the paint supplier can use may not be exactly the same as the color of the target color plate, and this difference will lead to the occurrence of the metamerism phenomenon. Especially during the matching process of parts and the whole vehicle, the colors are the same under the standard light source, but there are two colors under the cold light conditions of the automotive inspection line, and this phenomenon is absolutely unacceptable to customers. Therefore, at present, both customers and paint suppliers have gradually strengthened the management of metamerism abnormalities and quantified this phenomenon, that is, setting the color difference between different light sources and the standard color, such as requiring that the color difference value ΔE is less than 0.5 under the three light sources of D65, A, and F11.

[0004] At present, the only way to solve metamerism is to rely on experience, continuously replace the color pastes to prepare new mixed color pastes for a large number of tests, and try to find the pigments consistent with those used in the standard plate. Such a color matching efficiency is too low, and in many cases, no suitable color matching scheme can be found, resulting in the consequence that it cannot be solved, and thus customer resources will be lost. Therefore, there is an urgent need to develop a color matching method for efficiently solving the metamerism phenomenon. Summary of the Invention

[0005] Aiming at the above problems existing in the prior art, the purpose of the present invention is to provide a color matching method for efficiently solving the metamerism phenomenon of automotive coatings.

[0006] To achieve the above object, the technical solution adopted by the present invention includes:

[0007] The present invention discloses a color matching method for efficiently solving the metamerism phenomenon of automotive coatings, including the determination of the initial color paste formula and the determination of the target color paste formula;

[0008] 1) Determination of the initial color paste formula:

[0009] 1-1) According to different categories of coating colors, all color pastes required for preparing each pigment category are delimited; each time, any two color pastes are selected from the delimited color pastes for combination, the color values of the mixed color pastes obtained at different proportions are measured, the functional relationship between the proportion change of the color pastes and the color values of the mixed color pastes is established, and based on the same functional relationship establishment method, the functional relationship between the proportion change of the color pastes and the color values of the mixed color pastes under any two-color paste combinations is obtained, and a color database for different color categories is obtained;

[0010] 1-2) According to the color of the target color plate, a color database similar to the color of the target color plate is selected, and one or two color pastes are selected to simulate and match the color of the target color plate. The color prediction value of each simulation match is directly obtained through the color database, and each color prediction value is compared with the color value of the target color plate. If the color difference ΔE < 5 occurs, the color paste combination is the initial color paste formula close to the color of the target color plate; otherwise, step 1-3 is performed;

[0011] 1-3) More than three different color pastes are selected to simulate and match the color of the target color plate. Assume the mass ratio relationship of each color paste, and each color paste is numbered and recorded as color paste 1, color paste 2... color paste i, where i is a positive integer ≥ 3;

[0012] The usage amount of each color paste is split one by one. Each time, one color paste is split. Starting from color paste 1, under the splitting rule that the mass fraction of each split color paste 1 unit is not less than 5 wt% of the mass fraction of color paste 1, color paste 1 is split into i - 1 color paste 1 units with the same or different mass fractions, and the obtained color paste 1 units are randomly paired with color paste 2... color paste i one by one to obtain i - 1 mixed slurry groups containing color paste 1 units;

[0013] Based on the same splitting rule and pairing method, color paste 2... color paste i are respectively split and paired to obtain i - 1 mixed slurry groups containing color paste 2 units... i - 1 mixed slurry groups containing color paste i units;

[0014] 1-4) According to the established color database, the color values of each mixed slurry group are calculated respectively, and then the color prediction difference of the mixed slurry group containing color paste j unit is calculated according to formula 1 until M j ≤ 20;

[0015] M j = (X j 2 + Y j 2 + Z j 2 ) 1 / 2 Formula 1;

[0016] Wherein, M j is the color prediction difference value of the mixed slurry group containing the color paste j unit, X j is the value obtained by successively taking the difference of the i - 1 L values obtained from the mixed slurry group containing the color paste j unit, Y j is the value obtained by successively taking the difference of the i - 1 a values obtained from the mixed slurry group containing the color paste j unit, Z j is the value obtained by successively taking the difference of the i - 1 b values obtained from the mixed slurry group containing the color paste j unit, and j takes positive integers from 1 to i;

[0017] When splitting the color paste k, if M k ≤ 20, where k ≤ j, then the average values of all L values, a values, and b values in the mixed slurry group containing the color paste k unit are respectively obtained to get value, value and value. Compare the value, value and value with the color values of the target color plate. If the color difference ΔE < 5, then the scheme of splitting the color paste k to obtain the mixed slurry group is considered an effective color paste combination scheme close to the color of the target color plate, that is, the initial color paste formula. Otherwise, adjust the mass ratio relationship of each color paste, and repeat steps 1 - 3 and 1 - 4 until a combination scheme with ΔE < 5 is obtained;

[0018] 2) Determination of the target color paste formula:

[0019] After determining the initial color paste formula, obtain the true value of the color of the initial color paste formula through plate - making tests. Compare the L value, a value, and b value of the initial color paste formula with the L value, a value, and b value of the target color plate respectively, and calculate the differences ΔL, Δa, and Δb between the initial color paste formula and the target color plate;

[0020] According to the difference situation, add supplementary color paste 1, supplementary color paste 2... supplementary color paste n for adjusting its color value to the initial color paste formula respectively, where n is a positive integer ≥ 3, to obtain the mixed slurry under the addition amount of each supplementary color paste, and establish a one - dimensional linear relationship between the color change difference before and after adding the supplementary color paste and the addition amount of the supplementary color paste;

[0021] Based on the one-dimensional linear relationship and the difference data, calculate the exact addition amounts of each supplementary color paste, and add the calculated exact addition amounts to the initial color paste formula to obtain the target color paste formula.

[0022] Further, the determination of the exact addition amount in step 2 is such that ΔE between the target color paste formula and the target color board color is < 0.5.

[0023] Further, each functional relationship is obtained through data analysis software.

[0024] Further, each functional relationship is obtained by means of trend line fitting in excel software.

[0025] Further, in step 1, when establishing the functional relationship between the proportion change of the color paste and the color value of the mixed color paste, a functional relationship is established between the proportion change of one of the color pastes in the mixed color paste and the color value of the mixed color paste.

[0026] Further, the range of the proportion change of the color paste in the mixed color paste is 0 - 100 wt%.

[0027] Further, within the range of the proportion change, at least 7 or more color values of the mixed color paste with different color paste proportions are evenly measured.

[0028] Further, the addition amount of each supplementary color paste is 0.1 - 30 wt% relative to the mass of the initial color paste formula.

[0029] Further, the Lab value is the color data measured based on the D65 light source, A light source, and F11 light source.

[0030] Further, under the D65 light source, A light source, and F11 light source, the calculated ΔE is less than 0.5.

[0031] Advantages of the present invention:

[0032] The color matching method provided by the present invention can predict the color value of an unknown color paste combination through the established color database and color paste splitting logic, thereby efficiently obtaining an initial color paste formula close to the color of the target color board. Compared with the conventional color matching methods such as visual comparison and color matching experience to directly obtain the initial formula, it has higher accuracy and higher color matching efficiency. In addition, after determining the initial color paste formula, various supplementary color pastes are added to precisely adjust the color value, so that the finally obtained target color paste formula is not only closer to the color of the target color board provided by the customer, but also there is no metamerism phenomenon, and the ΔE obtained under the D65 light source, A light source, and F11 light source is less than 0.5. Brief Description of the Drawings

[0033] The following further details the specific embodiments of the present invention in conjunction with the drawings.

[0034] Figure 1a Shows the function relationship diagram of the proportion (x) of color paste 2 and the L value (y) under the D65 light source based on the data in Table 2.

[0035] Figure 1b Shows the function relationship diagram of the proportion (x) of color paste 2 and the a value (y) under the D65 light source based on the data in Table 2.

[0036] Figure 1c Shows the function relationship diagram of the proportion (x) of color paste 2 and the b value (y) under the D65 light source based on the data in Table 2.

[0037] Figure 2a Shows the function relationship diagram of the proportion (x) of color paste 2 and the L value (y) under the A light source based on the data in Table 2.

[0038] Figure 2b Shows the function relationship diagram of the proportion (x) of color paste 2 and the a value (y) under the A light source based on the data in Table 2.

[0039] Figure 2c Shows the function relationship diagram of the proportion (x) of color paste 2 and the b value (y) under the A light source based on the data in Table 2.

[0040] Figure 3a Shows the function relationship diagram of the proportion (x) of color paste 2 and the L value (y) under the F11 light source based on the data in Table 2.

[0041] Figure 3b Shows the function relationship diagram of the proportion (x) of color paste 2 and the a value (y) under the F11 light source based on the data in Table 2.

[0042] Figure 3c Shows the function relationship diagram of the proportion (x) of color paste 2 and the b value (y) under the F11 light source based on the data in Table 2. Detailed implementation manners

[0043] To more clearly illustrate the present invention, the present invention and the accompanying drawings are further described below in conjunction with preferred embodiments. It should be clear that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0044] In the case of clarifying and explaining the object of the present invention through the following embodiments, the components of the composition are explained with parts by weight as the general standard. Without special instructions, for the sake of simplicity, "parts" described in the embodiments of the present invention have the same meaning as parts by weight.

[0045] When determining the initial color paste formula close to the color of the target color board by traditional color matching methods, it is usually based on color matching experience and visual comparison effects. Through countless times of sample board tests, a close target formula is adjusted. There are obvious visual limitations and experience dependencies. Not only is the color matching efficiency low, but also the phenomenon of metamerism is likely to occur. If the phenomenon of metamerism occurs, it may mean the failure of development or a great increase in workload.

[0046] Therefore, according to the specific embodiments of the present invention, a color matching method for efficiently solving the metamerism phenomenon of automotive coatings is provided. The color matching method is divided into two parts. The first part is the determination of the initial color paste formula, which can be understood as the preliminary screening of the color paste combination. The main work is to initially select the types of color pastes and determine the proportion of color pastes. The second part is the determination of the target color paste formula, which can be understood as the further precise adjustment of the initial color paste formula. The main work is to add supplementary color pastes to achieve targeted adjustment to make up for the difference between the initial color paste formula and the color value of the target color board, and at the same time eliminate the metamerism problem.

[0047] When determining the initial color paste formula, the specific steps are as follows:

[0048] 1-1) Establish a color database for each color category

[0049] At present, there are a wide variety of automotive paint colors, but they are nothing more than common colors such as red, green, orange, yellow, blue, black, brown, and white. When formulating a specific color category, technicians are clear about all the color pastes that may be used for formulating this color category. After the range of the types of color pastes used is determined, it is necessary to establish a color database for each color category. First, randomly select two color pastes from these color pastes for combination each time. By adjusting the proportion of one of the two color pastes in the mixed color paste, mixed color pastes with different proportions are obtained, and then the true color values of the mixed color pastes with different proportions are measured. The range of proportion change is usually 0 - 100wt%, and multiple specific proportions for formulation should be set within this range of proportion change. Using a limited number of proportions and the corresponding color value data, the functional relationship between the proportion change of the color paste and the color value of the mixed color paste is fitted. Therefore, when selecting the specific proportion to be formulated, it is necessary to ensure both the quantity of the proportion to be formulated, which should not be too small, and it is advisable to formulate more than 7 different proportions of the color paste, and also to ensure that the proportions to be formulated are evenly distributed and should not be concentrated, so that the credibility of the fitted functional relationship is relatively high. Based on the same method, by changing the types of color pastes, the functional relationship between the proportion change of the color paste and the color value of the mixed color paste under the new color paste combination is obtained, and finally all the functional relationships for any two-color paste combinations are obtained, thus successfully establishing the color database for this color category. Of course, other color categories can be obtained by referring to the above method. This work belongs to the preliminary work of the present invention, and it is necessary to make a test board for each combination to obtain the true color value data. If a color database with a similar corresponding relationship has been established in previous research, there is no need to establish it repeatedly, and the work of the present invention can start from steps 1 - 2.

[0050] 1 - 2) Simulated formulation of combinations of no more than two types of color pastes

[0051] After obtaining the target color plate, the technician first selects a color database with colors similar to the target color plate based on the color of the target color plate, and then preliminarily judges the color paste combination required for the color of the target color plate based on the color mixing experience. The color mixing experience mentioned here is a conventional skill that should be possessed by those skilled in the art. For example, if the color of the target color plate is blue, a blue paste will be selected as the main color paste first. If the blue phase is insufficient, another blue paste or a mixture of two or more blue pastes needs to be replaced. If the red phase is lacking, a purple paste needs to be added, etc. If it is preliminarily judged that good color matching can be achieved using one or two color pastes, then simulate the mixing and directly read the color prediction value from the color database, and then compare the color prediction value with the color value of the target color plate. If the color difference ΔE < 5, it means that this color paste combination is the initial color paste formula close to the color of the target color plate. If ΔE < 5 still cannot be achieved after multiple attempts, and it is found that more color paste types need to be added for better simulation of the mixing, then perform the operations in step 1-3. Those skilled in the art can understand that if the technician directly selects more than three types of color pastes for simulation of the mixing according to the color mixing experience, steps 1-2 can be directly skipped and step 1-3 can be performed.

[0052] 1-3) Simulation of mixing with combinations of more than three types of color pastes

[0053] When simulating the mixing of combinations of more than three types of color pastes, color paste splitting is required, that is: select the color pastes used for color mixing, number each color paste separately, denoted as color paste 1, color paste 2... color paste i, where i is a positive integer ≥ 3;

[0054] When splitting the color paste, only one color paste is split each time. Taking color paste 1 as an example, under the splitting rule that the mass fraction of each split color paste 1 unit is not less than 5wt% of the mass of color paste 1, split color paste 1 into i - 1 color paste 1 units with the same or different mass fractions; if the mass fraction of the split color paste 1 unit is too small, it will not be able to play the role of color paste splitting.

[0055] Randomly pair the obtained color paste 1 units with color paste 2... color paste i one by one to obtain i - 1 groups of mixed slurries containing color paste 1 units;

[0056] Before splitting the color paste, the mass fractions of color paste 1, color paste 2... color paste i can be arbitrarily specified, and the mass fractions of different color pastes can be the same or different. For example, assume that the mass fractions of color paste 1, color paste 2... color paste i are all 15 parts. Then when splitting color paste 1, color paste 1 needs to be split into i - 1 color paste 1 units, and the mass fractions of the i - 1 color paste 1 units can be the same or different, as long as the total mass fraction of the i - 1 color paste 1 units is still 15 parts. Later, it needs to be verified through calculation whether the assumption of 15 parts for all is reasonable.

[0057] Based on the same splitting rules and pairing methods, split and pair the color pastes 2... color paste i respectively, to obtain i - 1 mixed paste groups containing color paste 2 units... i - 1 mixed paste groups containing color paste i units.

[0058] 1 - 4) Calculation and analysis

[0059] According to the color database established in Step 1 - 1, calculate the color values of each mixed paste group respectively, and then calculate the color prediction difference of the mixed paste group containing color paste j units according to Formula 1 until M j ≤20;

[0060] M j =(X j 2 +Y j 2 +Z j 2 ) 1 / 2 Formula 1;

[0061] Among them, M j is the color prediction difference of the mixed paste group containing color paste j units, X j is the value obtained by successively taking the difference of the i - 1 L values obtained from the mixed paste group containing color paste j units, Y j is the value obtained by successively taking the difference of the i - 1 a values obtained from the mixed paste group containing color paste j units, Z j is the value obtained by successively taking the difference of the i - 1 b values obtained from the mixed paste group containing color paste j units, and j takes positive integers from 1 to i;

[0062] To illustrate the above calculation process more clearly, the following is an example. For example, when calculating M 1 , that is, to count the color situation of split color paste 1, first, it is necessary to find the functional relationships between color paste 1 and color paste 2... color paste 1 and color paste i from the previously established color database respectively, and then use the obtained functional relationships to calculate the L values, a values, and b values in each mixed paste group, obtaining a total of i - 1 L values, i - 1 a values, and i - 1 b values. Then, subtract these i - 1 L values successively to get X 1 , subtract these i - 1 a values successively to get Y 1 , subtract these i - 1 b values successively to get Z 1 , and then substitute them into Formula 1 to obtain the data M 1 . In this calculation process, actually, both the types of split color pastes and the combination schemes after splitting are adjusted, so as to complete the calculation of prediction data under the combination of a large number of unknown mixed paste groups, and thus more accurate color prediction values can be obtained.

[0063] If M is obtained when splitting color paste k k with a result (k ≤ j) of ≤ 20, then the sum of all L values, a values, and b values in the mixed slurry group containing color paste k units is calculated and averaged to obtain value, value, and value. The value, value, and value are compared with the color values of the target color board. If the color difference ΔE < 5, the scheme of splitting color paste k to obtain the mixed slurry group is considered an effective color paste combination scheme close to the color of the target color board. Otherwise, repeat steps 1 - 3 and steps 1 - 4 to re - split the color paste and calculate the data until a combination scheme with ΔE < 5 is obtained. Finally, determine the color paste combination scheme, which is the initial color paste formula.

[0064] By continuously trying different types and quantities of color pastes, the color prediction value obtained is made close to the color value of the target color board to obtain the initial color paste formula. During this process, the types and quantities of color pastes can be adjusted arbitrarily. The calculation of the color prediction value is all obtained through fitting curves and calculations in the color database, avoiding frequent paint - making, spraying on the board, and testing operations, and having a great efficiency advantage.

[0065] 2) Determination of the target color paste formula:

[0066] After the initial color paste formula is determined, the true value of the color of the initial color paste formula is obtained through plate - making tests. The L value, a value, and b value of the initial color paste formula are respectively compared with the L value, a value, and b value of the target color board color, and the differences ΔL, Δa, and Δb between the initial color paste formula and the target color board color are calculated to clarify the adjustment direction of the initial color paste formula. The adjustment principle is to add supplementary color paste and use its influence on the color value to make the adjusted color value closer to the color value of the target color board;

[0067] There are certain principles in selecting the supplementary color paste here. Try to introduce as few supplementary color pastes as possible and try not to introduce color pastes outside the initial color paste formula. If the original color pastes cannot meet the requirements, then introduce new color pastes from the corresponding color paste library.

[0068] Technicians need to clarify the influence of the types and dosages of supplementary color pastes on the color values of the initial color paste formula. Therefore, different supplementary color pastes should be added to the initial color paste formula one by one, and the color values of the formula after addition should be measured. The addition amounts of different supplementary color pastes can be the same or different. Then, compare the color change differences before and after addition, and approximately consider that the color change difference is in a proportional function relationship with the addition value to determine its one-dimensional linear relationship. For example, when the addition amount of a certain supplementary color paste is 2%, the color values change by ΔL’ = 1.2, Δa’ = -1.3, and Δb’ = 2.6 respectively. Then, it can be approximately considered that Y = 0.6X, where Y represents ΔL’ and X represents the addition percentage. Similarly, the other two groups of one-dimensional linear relationships can be obtained accordingly. The one-dimensional linear relationship expression is convenient for determining the precise addition amounts of each supplementary color paste, and finally, through data calculation, the target color paste formula that matches the color of the target color board is obtained.

[0069] Furthermore, considering the problem of metamerism, when collecting the color value data in each step, it is best to collect the color value data under the D65 light source, A light source, and F11 light source respectively. Of course, the ΔE of the target color paste formula determined by the color matching method of the present invention is less than 0.5 under the D65 light source, A light source, and F11 light source.

[0070] Those skilled in the art can understand that the above-obtained target color paste formula is only a color paste combination scheme that can match the color of the target color board. Many color paste combination schemes that meet the requirements can be derived by using the method of the present invention. However, considering the actual problems and development costs, providing one of the color paste combination schemes meets the requirements.

[0071] The technical solution of the present invention will be further described below through specific embodiments.

[0072] Embodiment

[0073] A customer provides a target color board (blue), and its color value data is shown in Table 1.

[0074] Table 1

[0075] Color value 45° / D65 45° / A 45° / F11 L 10.08 11.46 10.27 a -2.16 3.39 2.51 b -17.54 -15.69 -17.63

[0076] Based on the fact that the color of the target color plate is blue, the types of main color pastes that may be used when formulating blue paint are found from the color paste library. After statistics, a total of 6 color pastes are required: AR-2000(T)G314 / BF-21PASTE UDP blue paste, AR-2000(T)HOSTAPERM VITOLET 16% color paste, AR-2000(T)EMPEROR BLACK KAI UDP, AR-2000(T)WHITE water-based white paste, AR-2000(adjust)3011 / BF-21PASTE UDP (semi) blue paste, AR-2000(T)6520BULUE UDP. Then, combined with the actual color situation of the target color plate, the usage of color pastes is streamlined. Finally, the possible types of color pastes to be used are determined as: AR-2000(T)G314 / BF-21PASTE UDP blue paste, AR-2000(T)HOSTAPERM VITOLET 16% color paste, AR-2000(T)EMPEROR BLACK KAI UDP, AR-2000(T)WHITE water-based white 0, which are respectively recorded as color paste 1, color paste 2, color paste 3, and color paste 4.

[0077] Color paste 1 and color paste 2 are combined to obtain a mixed color paste, and the true color values of the proportion of color paste 2 in the mixed color paste from 0 - 100 wt% are tested. The obtained data are shown in Table 2.

[0078] Table 2

[0079]

[0080] Note: The percentage refers to the mass percentage of color paste 2 in the mixed color paste.

[0081] Based on the data in Table 2, the functional relationship between the proportion of color paste 2 and the color value is fitted through excel software. The functional relationship diagram is shown in Figure 1a - Figure 3c , where the solid line represents the curve actually drawn according to the measured true values, and the dashed line represents the fitted curve. The obtained functional relationship formula is as follows:

[0082] D65 light source

[0083] (1) The relationship between the proportion (x) of color paste 2 and the L value (y) is: y = 59.635x 6 - 169.79x 5 + 207.36x 4 - 144.93x 3 + 59.536x 2 - 11.353x + 3.546 R2 = 0.9872 (Formula 1.1)

[0084] (2) The relationship between the proportion (x) of color paste 2 and the a value (y) is: y = -370.08x 6 + 1263.3x 5 - 1619.2x 4 + 950.69x 3 - 232.36x 2 + 4.7507x + 4.0896 R2 = 0.987 (Formula 1.2)

[0085] (3) The relationship between the proportion (x) of color paste 2 and the b value (y) is: y = 914.26x 6 - 2750.4x 5 + 3017.3x 4 - 1363.4x 3 + 117.11x 2 + 88.354x - 20.909 R2 = 0.9966 (Formula 1.3)

[0086] A light source

[0087] (1) The relationship between the proportion (x) of color paste 2 and the L value (y) is: y = 21.24x 6 - 47.858x 5 + 42.349x 4 - 22.373x 3 + 7.5183x 2 + 0.7068x + 2.2054 R2 = 0.9992 (Formula 1.4)

[0088] (2) The relationship between the proportion (x) of color paste 2 and the a value (y) is: y = -218.18x 6 + 664.98x 5 - 789.52x 4 + 452.44x 3 - 118.83x 2 + 8.9827x + 0.2631 R2 = 0.9759 (Formula 1.5)

[0089] (3) The relationship between the proportion (x) of color paste 2 and the b value (y) is: y = 817.53x 6 - 2418.6x 5 + 2541x 4 - 997.71x 3 - 37.031x 2 + 120.59x - 23.587 R2 = 0.9975 (Formula 1.6)

[0090] F11 light source

[0091] (1) The relationship between the proportion (x) of color paste 2 and the L value (y) is: y = 40.117x 6 - 100.87x 5 + 101.1x 4 - 55.739x 3 + 17.984x 2 - 1.384x + 2.3694 R2 = 0.9968 (Formula 1.7)

[0092] (2) The relationship between the proportion (x) of color paste 2 and the a value (y) is: y = - 307.92x 6 + 1001.9x 5 - 1251.9x 4 + 737.48x 3 - 191.84x 2 + 9.6841x + 2.2924 R2 = 0.9879 (Formula 1.8)

[0093] (3) The relationship between the proportion (x) of color paste 2 and the b value (y) is: y = 906.93x 6 - 2742.8x 5 + 3034.2x 4 - 1399.1x 3 + 142.16x 2 + 81.348x - 20.739 R2 = 0.9965 (Formula 1.9)

[0094] Referring to the above process, color paste 1 and color paste 3 are combined in different proportions to obtain a mixed color paste. The color values of the proportion of color paste 3 in the mixed color paste from 0 - 100 wt% are tested, and the functional relationship between the proportion of color paste 3 and the Lab value is fitted by excel software as follows:

[0095] D65 light source

[0096] (1) The relationship between the proportion (x) of color paste 3 and the L value (y) is: y = 156.87x 6 - 583.04x 5 + 852.15x 4 - 617.72x 3 + 229.68x 2 - 40.879x + 3.5765 R2 = 0.9856 (Formula 2.1)

[0097] (2) The relationship between the proportion (x) of color paste 3 and the a value (y) is: y = 125.58x 6 - 440.84x 5 + 621.35x 4 - 451.42x3 +179.19x 2 -38.004x + 4.0953R 2 = 0.9943 (Formula 2.2)

[0098] (3) The relationship between the proportion (x) of Color Paste 3 and the b value (y) is: y = -1276.7x 6 +4545.9x 5 -6401.7x 4 +4518.6x 3 -1667x 2 +301.89x - 21.062R 2 = 0.9854 (Formula 2.3)

[0099] A light source

[0100] (1) The relationship between the proportion (x) of Color Paste 3 and the L value (y) is: y = 52.904x 6 -215.5x 5 +339.65x 4 -261.21x 3 +101.13x 2 -18.583x + 2.2272R 2 = 0.9896 (Formula 2.4)

[0101] (2) The relationship between the proportion (x) of Color Paste 3 and the a value (y) is: y = -74.967x 6 +278.9x 5 -402.3x 4 +280.47x 3 -95.633x 2 +13.202x + 0.253R 2 = 0.987 (Formula 2.5)

[0102] (3) The relationship between the proportion (x) of Color Paste 3 and the b value (y) is: y = -1502.4x 6 +5346.2x 5 -7520.2x 4 +5297.4x 3 -1947x 2 +349.72x - 23.774R 2 = 0.9845 (Formula 2.6)

[0103] F11 light source

[0104] (1) The relationship between the proportion (x) of Color Paste 3 and the L value (y) is: y = 70.587x 6-279.46x 5 +430.36x 4 -324.63x 3 +123.62x 2 -22.259x + 2.3944R 2 = 0.9883 (Equation 2.7)

[0105] (2) The relationship between the proportion (x) of Color Paste 3 and the a value (y) is: y = 34.061x 6 -111.45x 5 +150.74x 4 -113.33x 3 +51.901x 2 -14.293x + 2.2955R 2 = 0.9972 (Equation 2.8)

[0106] (3) The relationship between the proportion (x) of Color Paste 3 and the b value (y) is: y = -1252.3x 6 +4461.6x 5 -6286.2x 4 +4439.7x 3 -1639.8x 2 +297.81x - 20.897R 2 = 0.9857 (Equation 2.9)

[0107] Referring to the above process, Color Paste 1 and Color Paste 4 are combined in different proportions to obtain a mixed color paste. The color values of Color Paste 4 in the mixed color paste with a proportion ranging from 0 - 100 wt% are tested, and the functional relationship between the proportion of Color Paste 4 and the Lab values is fitted through excel software as follows:

[0108] D65 light source

[0109] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 1581.9x 6 -3582.8x 5 +2745.4x 4 -630.97x 3 -170.27x 2 +141.54x + 3.5504R 2 = 0.9982 (Equation 3.1)

[0110] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = 1659.9x 6 -4222.5x 5 +4128.7x 4 -1986.7x3 +520.6x 2 -105.68x + 4.2747R 2 = 0.9902 (Formula 3.2)

[0111] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 3035.7x 6 -8008.2x 5 +8216.5x 4 -4196.8x 3 +1183.5x 2 -210.53x - 20.28R 2 = 0.9875 (Formula 3.3)

[0112] A light source

[0113] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2201.7x 6 -5317.5x 5 +4673.2x 4 -1723.8x 3 +173.7x 2 +78.461x + 2.3336R 2 = 0.9975 (Formula 3.4)

[0114] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = 2664.7x 6 -7134.2x 5 +7512.6x 4 -4008.3x 3 +1209.3x 2 -245.95x + 0.6944R 2 = 0.9907 (Formula 3.5)

[0115] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 4108.8x 6 -11005x 5 +11539x 4 -6078.8x 3 +1778.3x 2 -320.64x - 22.749R 2 = 0.9878 (Formula 3.6)

[0116] F11 light source

[0117] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2118.3x 6 -5104.8x5 +4465.5x 4 -1626.5x 3 +153.31x 2 +79.971x + 2.4857R 2 = 0.9977 (Equation 3.7)

[0118] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = 1213.7x 6 -2940.3x 5 +2657.9x 4 -1120.1x 3 +231.51x 2 -46.122x + 2.4203R 2 = 0.9894 (Equation 3.8)

[0119] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 3769.9x 6 -10137x 5 +10736x 4 -5766.9x 3 +1741.9x 2 -324.05x - 19.869R 2 = 0.9883 (Equation 3.9)

[0120] Referring to the above process, the Color Paste 2 and Color Paste 3 are combined in different proportions to obtain a mixed color paste. The Lab values of the proportion of Color Paste 3 in the mixed color paste from 0 - 100 wt% are tested, and the functional relationship between the proportion of Color Paste 3 and the Lab values is fitted by excel software as follows:

[0121] D65 light source

[0122] (1) The relationship between the proportion (x) of Color Paste 3 and the L value (y) is: y = -3.1051x 6 -31.585x 5 +106.24x 4 -116.69x 3 +54.417x 2 -12.642x + 3.989R 2 = 0.999 (Equation 4.1)

[0123] (2) The relationship between the proportion (x) of Color Paste 3 and the a value (y) is: y = 144x 6 -479.99x 5 +629.09x 4 -417.07x 3 +150.73x2 -28.141x + 1.3179R 2 = 0.9847 (Formula 4.2)

[0124] (3) The relationship between the proportion (x) of Color Paste 3 and the b value (y) is: y = -10.565x 6 + 9.1215x 5 + 35.34x 4 - 57.284x 3 + 23.66x 2 - 2.4044x + 2.1878R 2 = 0.9992 (Formula 4.3)

[0125] A light source

[0126] (1) The relationship between the proportion (x) of Color Paste 3 and the L value (y) is: y = -27.56x 5 + 78.323x 4 - 81.235x 3 + 35.876x 2 - 8.5741x + 3.796R 2 = 0.9993 (Formula 4.4)

[0127] (2) The relationship between the proportion (x) of Color Paste 3 and the a value (y) is: y = -34.755x 6 + 137.68x 5 - 209.97x 4 + 151.55x 3 - 50.163x 2 + 5.4111x + 0.1558R 2 = 0.9819 (Formula 4.5)

[0128] (3) The relationship between the proportion (x) of Color Paste 3 and the b value (y) is: y = -18.801x 6 + 43.738x 5 - 19.44x 4 - 16.801x 3 + 9.4822x 2 - 0.1468x + 2.0141R 2 = 0.9993 (Formula 4.6)

[0129] F11 light source

[0130] (1) The relationship between the proportion (x) of Color Paste 3 and the L value (y) is: y = -14.087x 6 + 9.1828x 5 + 46.672x 4-73.54x 3 +38.283x 2 -9.4734x + 3.5758R 2 = 0.9992 (Formula 4.7)

[0131] (2) The relationship between the proportion (x) of Color Paste 3 and the a value (y) is: y = 37.475x 6 -108.1x 5 +115.13x 4 -59.437x 3 +19.521x 2 -4.3999x - 0.2678R 2 = 0.9961 (Formula 4.8)

[0132] (3) The relationship between the proportion (x) of Color Paste 3 and the b value (y) is: y = -28.166x 6 +68.855x 5 -43.416x 4 -5.9909x 3 +5.9191x 2 +1.0598x + 1.7841R 2 = 0.999 (Formula 4.9)

[0133] Referring to the above process, Color Paste 2 and Color Paste 4 are combined in different proportions to obtain a mixed color paste. The color values of the proportion of Color Paste 4 in the mixed color paste from 0 - 100 wt% are tested, and the functional relationship between the proportion of Color Paste 4 and the Lab values is fitted by excel software as follows:

[0134] D65 light source

[0135] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2688x 6 -6479.8x 5 +5798x 4 -2320.7x 3 +389.69x 2 +9.2835x + 4.0781R 2 = 0.9955 (Formula 5.1)

[0136] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = -1203x 6 +2828.7x 5 -2521.2x 4 +1130.7x 3 -338.31x 2 +100.08x + 0.9778R2 = 0.9881 (Equation 5.2)

[0137] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 2904.8x 6 - 7617.7x 5 + 7899.2x 4 - 4220.8x 3 + 1314x 2 - 282.56x + 2.923R 2 = 0.9886 (Equation 5.3)

[0138] A light source

[0139] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2701.5x 6 - 6476.6x 5 + 5748x 4 - 2268.3x 3 + 373.35x 2 + 6.4788x + 3.9048R 2 = 0.9953 (Equation 5.4)

[0140] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = - 748.91x 6 + 1783.2x 5 - 1611.5x 4 + 733.63x 3 - 208.65x 2 + 50.116x + 0.0298R 2 = 0.9837 (Equation 5.5)

[0141] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 2764.3x 6 - 7184.2x 5 + 7367.5x 4 - 3890.3x 3 + 1211.3x 2 - 272.46x + 2.7522R 2 = 0.9892 (Equation 5.6)

[0142] F11 light source

[0143] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2767.4x 6 - 6646.7x 5 + 5920.9x 4 - 2359.2x3 +399.89x 2 +2.5267x + 3.7021R 2 = 0.9951 (Equation 5.7)

[0144] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = -919.35x 6 +2074.5x 5 -1726.3x 4 +705.03x 3 -211.55x 2 +76.701x - 0.5441R 2 = 0.9875 (Equation 5.8)

[0145] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 3158.6x 6 -8245.1x 5 +8513.3x 4 -4539.9x 3 +1423.5x 2 -313.8x + 2.6085R 2 = 0.989 (Equation 5.9)

[0146] Referring to the above process, the Color Paste 3 and Color Paste 4 are combined in different proportions to obtain a mixed color paste. The color values of the proportion of Color Paste 4 in the mixed color paste from 0 - 100 wt% are tested, and the functional relationship between the proportion of Color Paste 4 and the Lab values is fitted by excel software as follows:

[0147] D65 light source

[0148] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2130.1x 6 -5073.1x 5 +4525.1x 4 -1855x 3 +363.77x 2 -3.2932x + 0.813R 2 = 0.997 (Equation 6.1)

[0149] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = -79.24x 6 +225.31x 5 -245.66x 4 +126.61x 3 -29.843x 2 +1.063x - 0.0779R 2= 0.9976 (Equation 6.2)

[0150] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 84.136x 6 -157.01x 5 +95.228x 4 -32.407x 3 +22.906x 2 -13.703x + 0.0903R 2 = 0.9926 (Equation 6.3)

[0151] A light source

[0152] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2151.6x 6 -5128.1x 5 +4573.6x 4 -1870.6x 3 +364.37x 2 -3.5531x + 0.7899R 2 = 0.9969 (Equation 6.4)

[0153] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = -15.007x 6 +73.957x 5 -118.53x 4 +80.792x 3 -21.009x 2 -1.9284x - 0.094R 2 = 0.9988 (Equation 6.5)

[0154] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 99.894x 6 -203.04x 5 +135.94x 4 -39.057x 3 +17.266x 2 -12.605x + 0.0455R 2 = 0.9965 (Equation 6.6)

[0155] F11 light source

[0156] (1) The relationship between the proportion (x) of Color Paste 4 and the L value (y) is: y = 2153.1x 6 -5134.5x 5 +4583x 4 -1876.7x 3+365.88x 2 -3.4026x + 0.7916R 2 = 0.9970 (Formula 6.7)

[0157] (2) The relationship between the proportion (x) of Color Paste 4 and the a value (y) is: y = -29.923x 6 +97.598x 5 -123.51x 4 +74.711x 3 -20.554x 2 +0.4404x - 0.0907R 2 = 0.9988 (Formula 6.8)

[0158] (3) The relationship between the proportion (x) of Color Paste 4 and the b value (y) is: y = 390.53x 6 -1074.4x 5 +1100.2x 4 -516.57x 3 +119.04x 2 -20.446x + 0.0993R 2 = 0.9663 (Formula 6.9)

[0159] After obtaining the above formulas, a color database for any combination of two color pastes is obtained. Based on the color database, substituting the proportion of any color paste into the corresponding formula can obtain the predicted color value. In this way, it is no longer necessary to actually prepare and mix color pastes according to the proportion of color pastes for testing, saving time cost and raw material cost.

[0160] After the color database is established, infer the types and proportions of color pastes based on the color of the target color plate. By continuously adjusting the types and quantities of color pastes until the predicted color value is close to the color value of the target color plate (ΔE < 5), the initial types and formula of color pastes are obtained. The following is an example of the reasoning process:

[0161] Based on the color mixing experience, the initial formula is predicted to consist of two color pastes, Color Paste 1 and Color Paste 2, and the proportion of Color Paste 2 in the mixed color paste is 33%. Then the predicted color value is directly obtained through Formulas 1.1 - 1.9. The results are shown in Table 3. The data has a large difference from the target value, so the attempted solution cannot be used as the initial formula. This method can be tried multiple times. The process will not be elaborated here. The obtained color differences ΔE are all much greater than 5. Next, consider simulating and preparing with more than three types of color pastes.

[0162] Table 3

[0163] Color prediction 45° / A 45° / D65 45° / F11 L 2.80 2.95 2.72 a -0.50 -0.22 -0.22 b -1.95 -1.80 -2.27

[0164] When the number of color pastes ≥ 3, the prediction value needs to be obtained by using the method of splitting the color pastes. Since all calculations are performed in Excel after establishing the color database, the calculation process of the present invention is simulated by taking the initially screened color paste formula as an example. Assume that the initial color paste formula is combined according to the mass ratio of color paste 1, color paste 2, color paste 3, and color paste 4 being 1:1:1:1. The same method can be referred to for other color paste combinations and will not be elaborated here.

[0165] The various color pastes are split according to Table 4, and the corresponding predicted color value data is shown in Table 5.

[0166] Table 4

[0167]

[0168] Note: The percentage refers to the mass percentage of the color paste that is not split in the mixed paste group in the mixed paste group.

[0169] Table 5

[0170]

[0171]

[0172] From the experimental data in Table 4, it is found that M 4 = 18.57 < 20. Then, it is necessary to further check whether the scheme of splitting color paste 4 meets the requirement of ΔE < 5. The sum of all L values, a values, and b values under the same light source is calculated and then the average value is obtained to get value, value and value. The results for other light sources can be obtained by reference, and the obtained results are shown in Table 6.

[0173] Table 6

[0174]

[0175] The data in Table 6 is compared with the color values of the target color board, and ΔE is calculated. The process data is shown in Table 7. It is found that the requirement of ΔE < 5 is met under all three light sources. Therefore, this formula is determined as the initial color paste formula, that is, 10 parts of color paste 1, 10 parts of color paste 2, 10 parts of color paste 3, and 10 parts of color paste 4.

[0176] Table 7

[0177] Color value 45° / A 45° / D65 45° / F11 ΔL -0.98 -0.70 -1.22 Δa 0.80 1.30 1.10 Δb -3.90 -3.30 -4.30 ΔE 4.10 3.62 4.60

[0178] The second part is to make precise adjustments based on the obtained initial color paste formula to obtain the target color paste formula that is closer to the target color board and has no metamerism phenomenon.

[0179] After the initial formula is confirmed, the true color of the initial formula is confirmed through plate-making tests. See Table 8. According to the color situation, select complementary color pastes for small-scale experiments. The difference between the true color value and the color of the target color plate is shown in Table 9.

[0180] Table 8

[0181] True color value of the initial color paste formula 45° / A 45° / D65 45° / F11 L 7.74 8.7 7.71 a -0.82 4.18 2.76 b -17.41 -16.24 -18.22

[0182] Table 9

[0183] Difference between the true color value and the color of the target color board 45° / A 45° / D65 45° / F11 ΔL -2.34 -2.76 -2.56 Δa 1.34 0.79 0.25 Δb 0.13 -0.55 -0.59 ΔE 2.70 2.92 2.64

[0184] Select three color pastes, namely AR-2000(T)G314 / BF-21PASTE UDP blue paste, AR-2000(T)EMPEROR BLACK KAI UDP, and AR-2000(T)WHITE water-based white paste, as complementary color pastes and conduct small-scale experiments. Examine the influence of the addition amounts of the three color pastes on the change of the initial color paste color value respectively. The small-scale test results are shown in Table 10.

[0185] Table 10

[0186]

[0187] Note: The percentage of the complementary color paste is the percentage of the total mass of the initial color paste.

[0188] Based on the data in Table 10, establish a one-dimensional linear relationship between the color change difference before and after adding the complementary color paste and the addition amount of the complementary color paste, and the difference data in Table 9. Finally, it is determined that after adding 3wt% AR-2000(T)G314 / BF-21PASTE UDP blue paste, 7wt% AR-2000(T)EMPEROR BLACK KAI UDP, and 13wt% AR-2000(T)WHITE water-based white paste on the basis of the initial color paste formula, the color difference meets the requirement of ΔE < 0.5. The results are shown in Table 11.

[0189] Table 11

[0190]

[0191] Add the calculated accurate addition amount to the initial color paste formula to obtain the target color paste formula. See Table 12.

[0192] Table 12

[0193] Type of color paste Initial formula / part Increase after adjustment / part Final formula / part AR - 2000(T)G314 / BF - 21PASTE UDP blue paste 10 1.2 11.2 AR - 2000(T)HOSTAPERM VITOLET 16% color paste 10 0 10 AR - 2000(T)EMPEROR BLACK KAI UDP 10 2.8 12.8 AR - 2000(T)WHITE water - based white paste 10 5.2 15.2

[0194] What is described in this specification is only a relatively preferred specific embodiment of the present invention. The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the present invention. Any technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments according to the concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. A color matching method for efficiently solving the metamerism phenomenon of automotive coatings, characterized in that, it includes the determination of the initial color paste formula and the determination of the target color paste formula; 1) Determination of the initial color paste formula 1-1) According to different categories of coating colors, delimit all color pastes required for blending each pigment category; randomly select two color pastes from the delimited color pastes for combination each time, measure the color values of the mixed color pastes obtained at different proportions of the selected two color pastes, establish the functional relationship between the proportion change of the color pastes and the color values of the mixed color pastes, and based on the same functional relationship establishment method, obtain the functional relationship between the proportion change of the color pastes and the color values of the mixed color pastes under any two-color paste combination, and obtain the color databases of different color categories; 1-2) According to the color of the target color board, select the color database similar to the color of the target color board, select one or two color pastes to simulate and blend the color of the target color board. The color prediction value of each simulation blending is directly obtained through the color database, compare the color prediction value with the color value of the target color board. If the color difference ΔE < 5, then determine that the color paste combination is the initial color paste formula close to the color of the target color board. Otherwise, proceed to step 1-3; 1-3) Select more than three different color pastes to simulate and blend the color of the target color board, assume the mass ratio relationship of each color paste, number each color paste respectively, denoted as color paste 1, color paste 2... color paste i, where i is a positive integer ≥ 3; Split the usage amount of each color paste. Each time, split one color paste. Under the splitting rule that the mass fraction of each split color paste 1 unit is not less than 5wt% of the mass of color paste 1, split color paste 1 into i - 1 color paste 1 units with the same or different mass fractions, and randomly pair the obtained color paste 1 units with color paste 2... color paste i one by one to obtain i - 1 groups of mixed slurries containing color paste 1 units; Based on the same splitting rule and pairing method, split and pair color paste 2... color paste i respectively to obtain i - 1 groups of mixed slurries containing color paste 2 units... i - 1 groups of mixed slurries containing color paste i units; 1-4) According to the established color database, calculate the color values of each mixed slurry group respectively, and then calculate the color prediction difference of the mixed slurry group containing the color paste j unit according to Formula 1 until M j ≤ 20; M j = (X j 2 + Y j 2 + Z j 2 ) 1 / 2 Formula 1; Among them, M j is the color prediction difference value of the mixed slurry group containing the color paste j unit, X j is the value obtained by taking the differences of the i - 1 L values in sequence from the mixed slurry group containing the color paste j unit, Y j is the value obtained by taking the differences of the i - 1 a values in sequence from the mixed slurry group containing the color paste j unit, Z j is the value obtained by taking the differences of the i - 1 b values in sequence from the mixed slurry group containing the color paste j unit, and j takes positive integers from 1 to i; When splitting color paste k, M is obtained k ≤20, where k ≤ j. Then, the average values of all L values, a values, and b values in the mixed slurry group containing color paste k are calculated respectively to obtain value, value, and value. The value, value, and value are compared with the color values of the target color board. If the color difference ΔE < 5, the scheme of splitting color paste k to obtain the mixed slurry group is considered an effective color paste combination scheme close to the color of the target color board, that is, the initial color paste formula. Otherwise, the mass ratio relationship of each color paste is adjusted, and steps 1-3 and 1-4 are repeated until a combination scheme with ΔE < 5 is obtained; 2) Determination of the target color paste formula After the initial color paste formula is determined, obtain the true value of the color of the initial color paste formula through plate-making test, compare the L value, a value, and b value of the initial color paste formula with the L value, a value, and b value of the target color board color respectively, and calculate the differences ΔL, Δa, and Δb between the initial color paste formula and the target color board color; According to the difference situation, add supplementary color paste 1, supplementary color paste 2... supplementary color paste n for adjusting its color value to the initial color paste formula respectively, where n is a positive integer ≥ 3, to obtain the mixed slurry under the addition amount of each supplementary color paste, and establish the one-dimensional linear relationship between the color change difference before and after adding the supplementary color paste and the addition amount of the supplementary color paste; Based on the one-dimensional linear relationship and the difference data, calculate the accurate addition amount of each supplementary color paste, and add the calculated accurate addition amount to the initial color paste formula to obtain the target color paste formula.

2. The color matching method according to claim 1, characterized in that, the determination of the accurate addition amount in step 2 is to make ΔE between the target color paste formula and the target color board color < 0.

5.

3. The color matching method according to claim 1, It is characterized in that each functional relationship is obtained through data analysis software.

4. The color matching method according to claim 1, it is characterized in that each functional relationship is obtained by means of trend line fitting in excel software.

5. The color matching method according to claim 1, it is characterized in that when establishing the functional relationship between the proportion change of the color paste and the color value of the mixed color paste in step 1, the functional relationship is established between the proportion change of one of the color pastes in the mixed color paste and the color value of the mixed color paste.

6. The color matching method according to claim 5, it is characterized in that the range of the proportion change of the color paste in the mixed color paste is 0-100wt%.

7. The color matching method according to claim 6, it is characterized in that within the range of the proportion change, the color values of the mixed color paste with at least 7 different proportions of the color paste are measured evenly.

8. The color matching method according to claim 1, it is characterized in that the addition amount of each supplementary color paste is 0.1-30wt% relative to the mass of the initial color paste formula.

9. The color matching method according to claim 1, it is characterized in that the Lab value is the color data measured based on the D65 light source, A light source and F11 light source.

10. The color matching method according to claim 9, it is characterized in that under the D65 light source, A light source and F11 light source, the calculated ΔE is less than 0.5.

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