A method for preparing a high color fastness waterborne polyurethane pigmented coating based on pigment "black replacement"

Abstract

The application discloses a preparation method of a high-color-fastness water-based polyurethane colored coating based on pigment "black replacement", and aims at the problems of large pigment consumption, difficulty in resin coating and the like of a conventional water-based imitation leather dark-color coating, and the pigment "black replacement" technology takes color science subtraction color mixing as a principle, and quantitatively replaces different proportions of three primary color pigments by using compatible black pigments for a dark-color water-based polyurethane coating fabric, so that the pigment consumption of the dark-color coating is significantly reduced under the premise of ensuring color consistency, the coating property of resin material to the pigment is improved, and the existing water-based polyurethane wet rubbing fastness problem is solved. Meanwhile, the method has excellent compatibility and can be used together with water-based polyurethane modification, crosslinking agent addition, pigment modification and the like.

Description

Technical Field

[0001] This invention belongs to the field of waterborne polyurethane coating processing, and specifically relates to a method for preparing a high color fastness waterborne polyurethane coloring coating based on pigment "black replacement". Background Technology

[0002] Waterborne polyurethane (WPU) coatings use water instead of organic solvents as the dispersion medium, and the polyurethane is cured into a film through the evaporation of water under high temperature conditions. They offer advantages such as being green, environmentally friendly, safe, non-toxic, and pollution-free, representing the current development direction of the polyurethane coating industry. However, current waterborne polyurethane colored coatings still face several performance bottlenecks, such as poor rubbing fastness, abrasion resistance, and insufficient feel. Among these, the wet rubbing fastness problem of waterborne polyurethane imitation leather colored coatings, involving multiple factors including polyurethane resin materials, colorants, additives, and processing technology, has become a common and challenging issue in the field of waterborne polyurethane colored (primarily dark) coatings. On the one hand, different dark-colored coatings typically use a mixture of three primary colorants, resulting in high pigment usage (15-20 wt%) and difficulty in resin encapsulation. On the other hand, to satisfy the self-dispersing characteristics of waterborne polyurethane resin in the aqueous phase, hydrophilic groups or segments are often introduced into the waterborne polyurethane chain, leading to a certain degree of solubility of the resin segments in a wet state, thus affecting the film strength of the polyurethane resin and its encapsulation of pigment particles. Therefore, improving and solving the problem of wet rubbing color fastness of waterborne polyurethane coatings is of great significance for the promotion and application of waterborne polyurethane coatings. Currently, the main improvement methods include waterborne polyurethane modification, addition of crosslinking agents, and modification of chromophores or pigment molecules.

[0003] Patent CN106947049A discloses a method for preparing end-capped waterborne polyurethane. This method modifies the polyurethane by synthesizing a partially esterified styrene-maleic anhydride copolymer with hydroxyl groups. This results in a stronger anchoring effect of the polyurethane chains on organic pigment particles, which improves the dispersion stability of organic pigment particles in the waterborne polyurethane emulsion and the adhesion of the waterborne polyurethane adhesive to the pigments, thereby enhancing abrasion resistance and wash fastness.

[0004] Patent CN115521682A discloses a high-fixation waterborne coating and its preparation method. This method uses 2-ethylhexyl acrylate, N-acryloylmorpholine-modified waterborne polyurethane / acrylic acid mixture, and modified cellulose to significantly improve the hardness and abrasion resistance of the waterborne coating film while ensuring excellent transparency. The synergistic effect with the polyurethane prepared by epoxy-modified polyurethane results in excellent rubbing fastness and washing fastness, exhibiting high color fixation performance. Both methods enhance the interaction force between the waterborne polyurethane and pigment particles, thereby improving the wet rubbing fastness of the waterborne polyurethane. However, the above methods are complex and time-consuming, and the modification affects the feel of the film, failing to meet the comprehensive requirements of imitation leather fabrics for feel and abrasion resistance.

[0005] Patent CN111892694A discloses a method for preparing an external crosslinking agent for waterborne polyurethane. It uses imidazole ionic liquid-modified terminal hydroxyl polyether and polyisocyanate as raw materials, and obtains the external crosslinking agent for waterborne polyurethane through an addition polymerization reaction. The waterborne polyurethane external crosslinking agent prepared by this method has high ionic strength, good hydrophilicity, and high -NCO content. Therefore, the crosslinked waterborne polyurethane coating is non-sticky, and the strong ionic bonding enhances the molecular forces between PU molecular chains, giving the crosslinked polyurethane strong mechanical strength and good comprehensive properties such as water resistance, wet rubbing resistance, and heat resistance. Although the addition of the crosslinking agent can improve the wet rubbing color fastness of waterborne polyurethane, the increased crosslinking density of the coating material improves hardness and strength, but reduces softness and extensibility, which is detrimental to its application in textiles.

[0006] Patent CN104262570A discloses a method for preparing waterborne polyurethane dyes based on black chromophores in diols. This method involves reacting the amino or hydroxyl groups contained in the molecular structure of three black dyes with chloroethanol to obtain three black diols. These black diols are then combined with smaller molecule diols, partially or completely replacing the smaller molecule diols, to prepare a black waterborne polyurethane dye. Because the black chromophores are distributed in the polyurethane chain segments through chemical incorporation, this waterborne polyurethane exhibits excellent colorfastness.

[0007] Patent CN114230759A discloses a method for synthesizing a hydrolysis-resistant, high-color-fastness waterborne polyurethane emulsion. This method involves a stepwise polymerization reaction using oligomeric diols, aliphatic diisocyanates, vinyl-modified Maya blue attapulgite hybrid pigments, ethanolamine-based hydrophilic chain extenders, 2-hydroxyethyl acrylate crosslinking agents, and glycerol crosslinking agents to synthesize a polyurethane prepolymer with Maya blue attapulgite hybrid pigments modified in the side chains. The final product is a hydrolysis-resistant, high-color-fastness waterborne polyurethane emulsion. This waterborne polyurethane emulsion can effectively improve the water resistance of waterborne polyurethane products and enhance their mechanical properties and color fastness in the production of waterborne polyurethane coatings and synthetic leather products. While the above method significantly improves the rubbing fastness of waterborne polyurethane, its limited color options and lack of colored waterborne polyurethane dyes restrict its application in imitation leather coloring coatings.

[0008] Patent CN106496489A discloses a water-soluble color chain extender, a copolymeric colored polyurethane emulsion, and a colored polyurethane-acrylate copolymer emulsion, as well as their preparation methods. This method addresses color fastness issues by modifying the polyurethane molecular chain with a water-soluble color chain extender containing at least one chromophore group and at least two amino groups. However, this method suffers from poor controllability during synthesis due to the vigorous reaction between amino groups and isocyanate groups, leading to gelation. Summary of the Invention

[0009] The purpose of this invention is to provide a method for preparing a high-colorfastness waterborne polyurethane coloring coating based on pigment "black substitution." Addressing the problems of large pigment usage and difficulty in resin encapsulation in conventional waterborne imitation leather dark coatings, this invention utilizes the basic principle of subtractive color mixing in color science to provide a pigment "black substitution" strategy. By quantitatively replacing different proportions of the three primary color pigments with a compatible black pigment, the amount of dark coating pigment is significantly reduced while maintaining color consistency. This improves the resin material's encapsulation of the pigment, thereby improving and solving the problem of wet rubbing colorfastness in existing waterborne polyurethanes. Furthermore, this method has excellent compatibility and can be used in conjunction with waterborne polyurethane modification, crosslinking agent addition, and pigment modification methods.

[0010] To solve the above technical problems, the following technical solution is adopted:

[0011] A method for preparing a high-colorfastness waterborne polyurethane coloring coating based on pigment "black replacement" is characterized by comprising the following steps:

[0012] (1) Determine the proportion R of the three primary color pigments in a unit mass of "mixed neutral gray". n Y n B n ;

[0013] (2) Color parameters (L) of waterborne polyurethane cured films with different dosage ratios α of "mixed neutral gray" * value, a * value, b * Value, C * L (value and K / S value) was determined and fitted. * α The correlation formula between α and α is as follows:

[0014]

[0015] (3) Color parameters (L) of waterborne polyurethane curing films prepared with different dosage ratios of β-monochrome black K to form "monochrome neutral gray". * value, a * value, b * Value, C * L (value and K / S value) was determined and fitted. * β The correlation formula between β and β is as follows:

[0016]

[0017] (4) Determine the "black replacement" formula for the sample (the sample to be matched) and prepare the "black replacement" colored coating.

[0018] After optimization, the three primary color pigments in step (1) are red, yellow and blue, red, green and blue, or cyan, magenta and yellow.

[0019] After optimization, in step (1), determining the proportion of the three primary color pigments in the unit mass of "mixed neutral gray" means controlling the total amount of the mixed three primary color pigments to 1g, adding the three primary color pigments and adjusting the proportion, and measuring the C obtained by the colorimeter. * The value is used as an indicator to determine the amount of the three primary color pigments used to mix into "neutral gray", which is R. n Y n B n C is required * Value < 0.2.

[0020] After optimization, in steps (2) and (3), the color parameters are measured using a spectrophotometer, and the measurement parameters are set as follows: D65 standard illuminator, 10° standard observer, d / 8° measurement geometry, mirror containing SPIN and large aperture LAV26mm.

[0021] After optimization, in step (2), the preparation of waterborne polyurethane curing films with different dosage ratios α of "mixed neutral gray" is based on R determined in step (1). n Y n B n The proportions are first prepared by mixing different dosage ratios α.× (R n +Y n +B n The "mixed neutral gray" pigment was mixed, and then 50g of water-based polyurethane "mixed neutral gray" coloring coating liquid was prepared. Finally, it was cast into a square PTFE groove and dried at room temperature (25℃) for 48 hours to form a film.

[0022] After optimization, in step (2), the value of α for different dosage ratios ranges from 0.1 to 15.

[0023] After optimization, in step (3), the preparation of the "monochrome neutral gray" waterborne polyurethane curing film with different dosage ratios of β monochrome black K refers to first preparing black pigment with different dosages of β, then preparing 50g of waterborne polyurethane "monochrome neutral gray" coloring coating liquid, and finally casting it into a square PTFE groove and drying it at room temperature of 25°C for 48h to form a film.

[0024] After optimization, in step (3), the value of β for different dosage ratios ranges from 0.01 to 2.5g.

[0025] After optimization, in step (4), determining the "black replacement" formula for the sample (the sample to be matched) refers to: based on the three primary color formula R of the sample. m Y m B m ,according to α m Substituting the value into formula (1) yields L. α * value, then L β *=L α Substituting the * value into formula (2), we obtain the β value; based on the β value and α... m The value is used to obtain the "black replacement" formula K = β, R' for the sample (the sample to be matched). m =R m -α m *R n Y' m =Y m -α m *Y n B' m =B m -α m *B n ;where α m It refers to R m / R n Y m / Y n B m / B n The ratio with the smallest median value.

[0026] The above technical solution has the following beneficial effects:

[0027] 1. This invention provides a method for preparing a high-colorfastness waterborne polyurethane coloring coating based on pigment "black replacement." This method is based on the subtractive color mixing principle of color science. By using a compatible black pigment to quantitatively replace different proportions of the three primary color pigments, the amount of pigment used in dark coatings is significantly reduced while ensuring color consistency. This improves the pigment encapsulation properties of the resin material, thereby improving and solving the existing problems of dry and wet rubbing colorfastness of waterborne polyurethane. This method not only ensures the color and mechanical performance requirements of the waterborne polyurethane coloring coating but also reduces pigment usage costs and improves the dry and wet rubbing colorfastness of the waterborne polyurethane.

[0028] 2. This invention provides a method for preparing a high-color-fastness waterborne polyurethane colored coating based on pigment "black replacement". This method has excellent compatibility and can be used in conjunction with waterborne polyurethane modification, crosslinking agent addition, pigment modification, and other methods. It is applicable to different types of waterborne polyurethane and pigment particles, and has the advantages of wide applicability, simple process operation, safety, and environmental friendliness. Detailed Implementation

[0029] This invention aims to provide a method for preparing a high-color-fastness waterborne polyurethane coloring coating based on pigment "black replacement". The pigment "black replacement" technology is based on the principle of subtractive color mixing. For dark waterborne polyurethane fabrics, it uses a compatible black pigment to quantitatively replace different proportions of the three primary color pigments. While ensuring color consistency, it significantly reduces the amount of pigment used in the dark coating, improves the coating material's ability to encapsulate the pigment, and thus improves the wet rubbing color fastness of the coating film.

[0030] The technical solution of the present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0031] Example 1

[0032] (1) The amounts of Indigo Red HH-B, Indigo Yellow HH-2GD, and Indigo Blue HH-BC, the three primary color pigments used to mix to form "neutral gray" were determined using a colorimeter as R. n =0.45g, Y n =0.35g, B n =0.2g;

[0033] (2) Based on R determined in step (1) n Y n B n The proportions are first prepared by mixing different dosage ratios α. × (R n +Y n +B nA mixture of neutral gray pigments (α values ​​of 0.1, 0.3, 0.5, 0.7, 0.9, 2, 4, 6, 8, 10, 12, 14) was prepared, and 50g of each mixture was used to prepare a water-based polyurethane neutral gray coloring coating. The coatings were then cast into square PTFE grooves and dried at room temperature (25℃) for 48 hours to form films. The K / S, C*, L*, a*, and b* values ​​of the different water-based polyurethane coloring coating films were measured using a colorimeter. Based on the L* value, the L... * α The correlation formula between α and α.

[0034] (3) Indigo black H-G40A pigment with different dosages β (β = 0.02g, 0.04g, 0.06g, 0.08g, 0.1g, 0.2g, 0.4g, 0.6g, 0.8g, 1g, 1.5g, 2g, 2.5g) was prepared, and then 50g of waterborne polyurethane "monochrome neutral gray" coloring coating liquid was prepared for each. Finally, the coating was cast into a square PTFE groove and dried at room temperature (25℃) for 48h to form a film. The K / S value, C* value, L* value, a* value, and b* value parameters of the waterborne polyurethane coloring coating film with different concentrations were measured using a colorimeter. Based on the L* value, the L value was determined by fitting. * β The correlation formula between β and β.

[0035] (4) The color sample to be matched is a dark brown waterborne polyurethane cured film prepared from 2.75g Indigo Red HH-B, 2.75g Indigo Yellow HH-2GD, and 2g Indigo Blue HH-BC. According to... α m Substituting the value of 6.1 into formula (1) yields L. α * value, then L β *=L α Substituting the value of α into formula (2), we get β = 0.02. Based on the value of β and α... m The value yielded the following "black replacement" formula for the sample (to be matched): 0.02g Indigo Black H-G40A, 0.615g Indigo Yellow HH-2GD, and 0.78g Indigo Blue HH-BC.

[0036] (5) Based on the "black replacement" formula of the sample (to be matched) determined in step (4), prepare 50g of waterborne polyurethane "black replacement" coloring coating liquid, and finally cast it into a square PTFE groove and dry it at room temperature (25℃) for 48h to form a film. Refer to GB / T3920—2008 "Test Method for Color Fastness to Rubbing of Textiles" and use a rubbing fastness tester to test the dry and wet rubbing fastness of the waterborne polyurethane cured film, and refer to the standard gray scale to rate the color fastness of the cured film. The results are: dry rubbing fastness grade 5 and wet rubbing fastness grade 5.

[0037] Example 2

[0038] (1) The amounts of Indigo Red HH-G, Indigo Yellow HH-5GC, and Indigo Blue HH-2RD, the three primary color pigments used to mix to form "neutral gray" were determined using a colorimeter, and were R... n =0.4g, Y n =0.4g, B n =0.3g;

[0039] (2) Based on R determined in step (1) n Y n B n The proportions are first prepared by mixing different dosage ratios α. × (R n +Y n +B n A mixture of neutral gray pigments (α values ​​of 0.1, 0.3, 0.5, 0.7, 0.9, 2, 4, 6, 8, 10, 12, 14) was prepared, and 50g of each mixture was used to prepare a water-based polyurethane neutral gray coloring coating. The coatings were then cast into square PTFE grooves and dried at room temperature (25℃) for 48 hours to form films. The K / S, C*, L*, a*, and b* values ​​of the different water-based polyurethane coloring coating films were measured using a colorimeter. Based on the L* value, L was obtained through fitting. * α The correlation formula between α and α.

[0040] (3) Indigo black HH-GA pigment with different dosages β (β = 0.02g, 0.04g, 0.06g, 0.08g, 0.1g, 0.2g, 0.4g, 0.6g, 0.8g, 1g, 1.5g, 2g, 2.5g) was prepared, and then 50g of waterborne polyurethane "monochrome neutral gray" coloring coating liquid was prepared for each. Finally, the coating was cast into a square PTFE groove and dried at room temperature (25℃) for 48h to form a film. The K / S value, C* value, L* value, a* value, and b* value parameters of the waterborne polyurethane coloring coating film with different concentrations were measured using a colorimeter. Based on the L* value, L was obtained by fitting. * β The correlation formula between β and β.

[0041] (4) The color sample to be prepared is a coffee-colored waterborne polyurethane cured film made from 6g of Indigo Red HH-G, 8.5g of Indigo Yellow HH-5GC, and 3g of Indigo Blue HH-2RD. α m Substituting the value of 10 into formula (1) yields L. α * value, then L β *=L αSubstituting the value of α into formula (2), we get β = 0.05. Based on the value of β and α... m The value yielded the following "black replacement" formula for the sample (to be matched): 0.05g Indigo Black HH-GA, 2g Indigo Red HH-G, and 4.5g Indigo Yellow HH-5GC.

[0042] (5) Based on the "black replacement" formula of the sample (to be matched) determined in step (4), prepare 50g of waterborne polyurethane "black replacement" coloring coating liquid, and finally cast it into a square PTFE groove and dry it at room temperature (25℃) for 48h to form a film. Refer to GB / T3920—2008 "Test Method for Color Fastness to Rubbing of Textiles" and use a rubbing fastness tester to test the dry and wet rubbing fastness of the waterborne polyurethane cured film, and refer to the standard gray scale to rate the color fastness of the cured film. The results are: dry rubbing fastness grade 5 and wet rubbing fastness grade 5.

[0043] Example 3

[0044] (1) The amounts of the three primary color pigments—Indomethacin Red HH-F2G, Indomethacin Yellow HH-5GC, and Indomethacin Blue HH-BC—used in the mixing of "neutral gray" were determined using a colorimeter as R. n =0.32g, Y n =0.34g, B n =0.34g;

[0045] (2) Based on R determined in step (1) n Y n B n The proportions are first prepared by mixing different dosage ratios α. × (R n +Y n +B n A mixture of neutral gray pigments (α values ​​of 0.1, 0.3, 0.5, 0.7, 0.9, 2, 4, 6, 8, 10, 12, 14) was prepared, and 50g of each mixture was used to prepare a water-based polyurethane neutral gray coloring coating. The coatings were then cast into square PTFE grooves and dried at room temperature (25℃) for 48 hours to form films. The K / S, C*, L*, a*, and b* values ​​of the different water-based polyurethane coloring coating films were measured using a colorimeter. Based on the L* value, L was obtained through fitting. * α The correlation formula between α and α.

[0046] (3) Indigo black HH-GA pigment with different dosages β (β = 0.02g, 0.04g, 0.06g, 0.08g, 0.1g, 0.2g, 0.4g, 0.6g, 0.8g, 1g, 1.5g, 2g, 2.5g) was prepared, and then 50g of waterborne polyurethane "monochrome neutral gray" coloring coating liquid was prepared for each. Finally, the coating was cast into a square PTFE groove and dried at room temperature (25℃) for 48h to form a film. The K / S value, C* value, L* value, a* value, and b* value parameters of the waterborne polyurethane coloring coating film with different concentrations were measured using a colorimeter. Based on the L* value, the fitted L was obtained. * β The correlation formula between β and β.

[0047] (4) The color sample to be matched is a deep reddish-brown waterborne polyurethane cured film prepared from 10g Indigo Red HH-F2G, 6g Indigo Yellow HH-5GC, and 4g Indigo Blue HH-BC. α m Substituting the value of 11.7 into formula (1) yields L. α * value, then L β *=L α Substituting the value of α into formula (2), we get β = 0.1. Based on the value of β and α... m The values ​​yielded the following "black replacement" formula for the sample (to be matched): 0.1g Indigo Black HH-GA, 6.256g Indigo Red HH-F2G, and 2.022g Indigo Yellow HH-5GC.

[0048] (5) Based on the "black replacement" formula of the sample (to be matched) determined in step (4), prepare 50g of waterborne polyurethane "black replacement" coloring coating liquid, and finally cast it into a square PTFE groove and dry it at room temperature (25℃) for 48h to form a film. Refer to GB / T3920—2008 "Test Method for Color Fastness to Rubbing of Textiles" and use a rubbing fastness tester to test the dry and wet rubbing fastness of the waterborne polyurethane cured film, and rate the color fastness of the cured film with reference to the standard gray scale. The results are: dry rubbing fastness grade 5, wet rubbing fastness grade 4-5.

[0049] Example 4

[0050] (1) The amounts of Indigo Red HH-FGR, Indigo Yellow HH-2GD, and Indigo Blue HH-2RD, the three primary color pigments used to mix to form "neutral gray" were determined using a colorimeter, and were R. n =0.33g, Y n =0.33g, B n =0.34g;

[0051] (2) Based on R determined in step (1) n Y n Bn The proportions are first prepared by mixing different dosage ratios α. × (R n +Y n +B n A mixture of neutral gray pigments (α values ​​of 0.1, 0.3, 0.5, 0.7, 0.9, 2, 4, 6, 8, 10, 12, 14) was prepared, and 50g of each mixture was used to prepare a water-based polyurethane neutral gray coloring coating. The coatings were then cast into square PTFE grooves and dried at room temperature (25℃) for 48 hours to form films. The K / S, C*, L*, a*, and b* values ​​of the different water-based polyurethane coloring coating films were measured using a colorimeter. Based on the L* value, L was obtained through fitting. * α The correlation formula between α and α.

[0052] (3) Indigo black HH-GA pigment with different dosages β (β = 0.02g, 0.04g, 0.06g, 0.08g, 0.1g, 0.2g, 0.4g, 0.6g, 0.8g, 1g, 1.5g, 2g, 2.5g) was prepared, and then 50g of waterborne polyurethane "monochrome neutral gray" coloring coating liquid was prepared for each. Finally, the coating was cast into a square PTFE groove and dried at room temperature (25℃) for 48h to form a film. The K / S value, C* value, L* value, a* value, and b* value parameters of the waterborne polyurethane coloring coating film with different concentrations were measured using a colorimeter. Based on the L* value, L was obtained by fitting. * β The correlation formula between β and β.

[0053] (4) The color sample to be matched is a deep red waterborne polyurethane cured film prepared from 14g Indigo Red HH-FGR, 3.6g Indigo Yellow HH-2GD, and 0.6g Indigo Blue HH-2RD. According to... α m Substituting the value of 1.76 into formula (1) yields L. α * value, then L β *=L α Substituting the value of α into formula (2), we get β = 0.08. Based on the value of β and α... m The values ​​yielded the following "black replacement" formula for the sample (to be matched): 0.08g Indigo Black HH-GA, 13.42g Indigo Red HH-FGR, and 3.02g Indigo Yellow HH-2GD.

[0054] (5) Based on the "black replacement" formula of the sample (to be matched) determined in step (4), prepare 50g of waterborne polyurethane "black replacement" coloring coating liquid, and finally pour it into a square PTFE groove and dry it at room temperature (25℃) for 48h to form a film. Refer to GB / T3920—2008 "Test Method for Color Fastness to Rubbing of Textiles" and use a rubbing fastness tester to test the dry and wet rubbing fastness of the waterborne polyurethane cured film, and rate the color fastness of the cured film with reference to the standard gray scale. The results are dry rubbing fastness grade 4-5 and wet rubbing fastness grade 4.

[0055] Example 5

[0056] (1) The amounts of the three primary color pigments—Indomethacin Red HH-F2G, Indomethacin Yellow HH-5GC, and Indomethacin Blue HH-BC—used in the mixing of "neutral gray" were determined using a colorimeter as R. n =0.32g, Y n =0.34g, B n =0.34g;

[0057] (2) Based on R determined in step (1) n Y n B n The proportions are first prepared by mixing different dosage ratios α. × (R n +Y n +B n A mixture of neutral gray pigments (α values ​​of 0.1, 0.3, 0.5, 0.7, 0.9, 2, 4, 6, 8, 10, 12, 14) was prepared, and 50g of each mixture was used to prepare a water-based polyurethane neutral gray coloring coating. The coatings were then cast into square PTFE grooves and dried at room temperature (25℃) for 48 hours to form films. The K / S, C*, L*, a*, and b* values ​​of the different water-based polyurethane coloring coating films were measured using a colorimeter. Based on the L* value, L was obtained through fitting. * α The correlation formula between α and α.

[0058] (3) Indigo black HH-GA pigment with different dosages β (β = 0.02g, 0.04g, 0.06g, 0.08g, 0.1g, 0.2g, 0.4g, 0.6g, 0.8g, 1g, 1.5g, 2g, 2.5g) was prepared, and then 50g of waterborne polyurethane "monochrome neutral gray" coloring coating liquid was prepared for each. Finally, the coating was cast into a square PTFE groove and dried at room temperature (25℃) for 48h to form a film. The K / S value, C* value, L* value, a* value, and b* value parameters of the waterborne polyurethane coloring coating film with different concentrations were measured using a colorimeter. Based on the L* value, L was obtained by fitting. * β The correlation formula between β and β.

[0059] (4) The color samples to be matched are 5g of Indigo Red HH-F2G, 5g of Indigo Yellow HH-5GC, and 5g of Indigo Blue HH-BC, used to prepare a deep black waterborne polyurethane cured film. α m Substituting the value of 14.7 into formula (1) yields L. α * value, then L β *=L α Substituting the value of α into formula (2), we get β = 0.03. Based on the value of β and α... m The values ​​yielded a "black replacement" formula of 0.03g Indigo Black HH-GA and 0.296g Indigo Red HH-F2G for the sample (to be matched).

[0060] (5) Based on the "black replacement" formula of the sample (to be matched) determined in step (4), prepare 50g of waterborne polyurethane "black replacement" coloring coating liquid, and finally cast it into a square PTFE groove and dry it at room temperature (25℃) for 48h to form a film. Refer to GB / T3920—2008 "Test Method for Color Fastness to Rubbing of Textiles" and use a rubbing fastness tester to test the dry and wet rubbing fastness of the waterborne polyurethane cured film, and refer to the standard gray scale to rate the color fastness of the cured film. The results are: dry rubbing fastness grade 5 and wet rubbing fastness grade 5.

[0061] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for preparing a high-colorfastness waterborne polyurethane coloring coating based on pigment "black replacement", characterized in that... The steps include: (1) Determining the proportion R of the three primary color pigments in a unit mass of "mixed neutral gray". n Y n B n (2) Color parameters L of waterborne polyurethane curing film with different dosage ratios α "mixed neutral gray" * value, a * value, b * Value, C * Determination and fitting of L value and K / S value * α The correlation formula between α and α is as follows: The preparation of waterborne polyurethane curing films with different dosage ratios α"mixed neutral gray" is based on R determined in step (1). n Y n B n The proportions are first prepared by mixing different dosage ratios α. × (R n +Y n +B n The "mixed neutral gray" pigment was mixed, and then 50 g of water-based polyurethane "mixed neutral gray" coloring coating liquid was prepared. Finally, it was cast into a square PTFE groove and dried at room temperature (25 °C) for 48 h to form a film. The α value for different dosage ratios ranged from 0.1 to 15. (3) Color parameters L of "monochrome neutral gray" waterborne polyurethane curing film prepared with different dosage ratios of β monochrome black K * value, a * value, b * Value, C * Determination and fitting of L value and K / S value * β The correlation formula between β and β is as follows: The preparation of a "monochrome neutral gray" waterborne polyurethane curing film by different dosage ratios of black K (β) involves first preparing black pigments of different dosages (β), then preparing 50 g of waterborne polyurethane "monochrome neutral gray" coloring coating liquid, and finally casting the mixture into a square PTFE groove and drying it at room temperature (25 ℃) for 48 h to form a film. The value of β for different dosage ratios ranges from 0.01 to 2.5 g. (4) Determine the "black replacement" formula of the sample and prepare the "black replacement" coloring coating; The "black replacement" formulation for the sample refers to: the three primary color formulation R based on the sample. m Y m B m ,according to , α m Substituting the value into formula (1) yields L. α * value, then L β *=L α Substituting the value into formula (2), we obtain the β value; based on the β value and α... m The value is obtained by formulating the "black replacement" of the sample, K=β, R'. m =R m -α m *R n Y' m =Y m -α m *Y n B' m =B m -α m *B n ;where α m It refers to R m / R n Y m / Y n B m / B n The ratio with the smallest median value.

2. The method for preparing a high-colorfastness waterborne polyurethane coloring coating based on pigment "black replacement" according to claim 1, characterized in that: In step (1), the three primary color pigments are red, yellow, and blue; red, green, and blue; or cyan, magenta, and yellow.

3. The method for preparing a high-colorfastness waterborne polyurethane coloring coating based on pigment "black replacement" according to claim 1, characterized in that: In step (1), determining the proportion of the three primary color pigments in the unit mass of "mixed neutral gray" means controlling the total amount of the mixed three primary color pigments to 1 g, adding the three primary color pigments and adjusting the proportion, and measuring the C value obtained by a colorimeter. * The value is used as an indicator to determine the amount of the three primary color pigments used to mix into "neutral gray" as R. n Y n B n C is required * Value < 0.

2.

4. The method for preparing a high-colorfastness waterborne polyurethane coloring coating based on pigment "black replacement" according to claim 1, characterized in that: In steps (2) and (3), the color parameters are measured using a spectrophotometer, with the following measurement parameters set: D65 standard illuminator, 10° standard observer, d / 8° measurement geometry, mirror containing SPIN, and large aperture LAV26mm.

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