Dye dispersion for preparing colored laundry detergent and method for preparing colored laundry detergent

Abstract

The present application provides a dye dispersion containing polyhydric alcohol and water-soluble dye dispersed therein, and relates to the dye dispersion which has lower equipment contamination, is not easy to dye the equipment, is easy to clean, effectively improves the flexibility of the dye dispersion formula, and has lower viscosity compared with other colorant dispersions; the present application also provides a method for preparing colored laundry detergent, which comprises the following steps: preparing a dye dispersion and uniformly spraying the dye dispersion on laundry detergent base powder, and the dye dispersion contains polyhydric alcohol and water-soluble dye dispersed therein; the process can be independently arranged outside the preparation process of conventional laundry detergent, and no additional drying process is needed to remove water; the present application also provides the use of the dye dispersion for preparing colored laundry detergent and the colored laundry detergent prepared by the method for preparing colored laundry detergent.

Description

Technical Field

[0001] This invention relates to the field of laundry detergent preparation, and more specifically to a dye dispersion for preparing colored laundry detergent and a method for preparing colored laundry detergent using the dye dispersion. Background Technology

[0002] Laundry detergent is an essential cleaning agent in daily life. With the diversification of consumer demand, colored laundry detergents have emerged. The typical production process involves mixing detergent raw materials for fabric cleaning, such as various surfactants and detergent additives, to form a slurry. This slurry is then dried with hot air via a high-tower spray gun to obtain laundry detergent granules of a specific density and size. To give laundry detergent more functions to meet diverse needs, various additives, such as enzymes, polymers, fragrances, and nonionic surfactants, can be added in the post-blending stage to enrich product performance.

[0003] The existing preparation process in the field of colored laundry detergent, as disclosed in this invention, is typically a pre-mixing process, which involves preparing and mixing pigment raw materials with a slurry before the spraying process. Specifically, the basic flow of this process is to add an appropriate proportion of a certain pigment raw material to the slurry, mix it evenly, and then spray-dry and granulate it to obtain uniformly colored laundry detergent granules. However, such a production process can cause the spraying tower to become contaminated with pigment, affecting subsequent laundry detergent production. Cleaning the spraying tower is also time-consuming and labor-intensive.

[0004] The preparation process opposite to the pre-compounding process is called the post-compounding process, which can also be used in the production of colored laundry detergent. For example, CN110846140A discloses a preparation process for colored laundry detergent. This process uses nonionic surfactants to disperse dyes, which are then atomized and sprayed onto the surface of laundry detergent particles during the post-compounding process. In this process, the content of nonionic surfactants in the dye-nonionic surfactant solution is required to be 90-99.5%. Such a high content range will affect the total content of surfactants in the laundry detergent formulation. In particular, when the laundry detergent base powder formulation requires no nonionic surfactants to be added, the application of this preparation method will be severely limited.

[0005] Even so, post-compounding processes still possess significant advantages in the preparation of colored laundry detergents. This is because: firstly, post-compounding processes do not require large-scale modifications to existing laundry detergent production lines, only the addition of a spraying step to apply the prepared color dispersion to the detergent base powder; secondly, post-compounding processes impart additional color gradations to the laundry detergent to meet personalized needs. However, the application of post-compounding processes is currently limited because it inevitably introduces color dispersions into the original detergent granules. As an additional component, the introduction of dye dispersions alters the overall composition of the laundry detergent. Therefore, the selection of color dispersions is crucial when developing pre-compounding processes, and this selection directly affects the design of the colored laundry detergent preparation method. Summary of the Invention

[0006] The present invention provides a dye dispersion comprising a polyol and a water-soluble dye dispersed therein.

[0007] Regarding the selection of color dispersions used in post-compounding processes, the inventors discovered that the color dispersions introduced through the spraying process in post-compounding processes, as additional components in laundry detergent, should have as little impact as possible on the composition of the laundry detergent base powder. This means that the introduced color dispersions should contain as much color component as possible under a certain weight, and should also be able to meet the material requirements of the post-compounding process, especially the viscosity requirements in the spraying process.

[0008] The inventors noted that the spraying process in the post-processing is unavoidable. In order to save production costs, the spraying device is often used to prepare both white laundry detergent base powder and colored laundry detergent. Therefore, it is necessary to switch between colorant solution and colorless solution. This requires that the colorant solution does not easily stain the equipment and is easy to clean.

[0009] The inventors also noted that the advantage of the post-processing is that colored laundry detergent can be prepared by additionally spraying pigments for dyeing. Therefore, it is advantageous to be compatible with all currently available commercial laundry detergent base powder varieties and with laundry detergent varieties that use various types of surfactants as cleaning active ingredients. Such comprehensive factors are necessary.

[0010] The inventors also noted that the introduction of water in the post-processing requires an additional drying step, which is disadvantageous for industrial production. Therefore, it is advantageous to develop water-free dye dispersions and methods for preparing colored laundry detergent.

[0011] Accordingly, the inventors selected a water-soluble dye system using polyols as dispersants as the dye dispersion to overcome the aforementioned known problems. The dye dispersion of this invention, compared to other pigment dispersions, has lower equipment staining properties, is less likely to stain equipment, and is easier to clean. Polyols, as dispersants, are less expensive than surfactants, effectively improving the flexibility of dye dispersion formulations. Furthermore, compared to surfactants, especially nonionic surfactants, polyols have lower viscosity, which is advantageous for spraying processes. In addition, since the dye dispersion of this invention does not contain water, an additional drying process is unnecessary, broadening the application scenarios of this invention.

[0012] In addition, the inventors unexpectedly discovered that the viscosity of the dye dispersion using polymer pigments decreases with the pigment concentration in the dispersion. This makes it possible for polymer pigments to meet the condition of formulations without surfactants because they do not require the use of surfactants for dispersion, and also to achieve low viscosity and high pigment concentration because of their characteristic that the higher the concentration, the lower the viscosity. Therefore, polymer pigment dispersions have a very broad prospect in the preparation of colored laundry detergents in post-concentration processes.

[0013] The present invention also provides a method for preparing colored laundry detergent, comprising the following steps: preparing a dye dispersion and uniformly spraying the dye dispersion onto laundry detergent base powder, wherein the dye dispersion comprises a polyol and a water-soluble dye dispersed therein.

[0014] Regarding the process and steps for preparing colored laundry detergent, the inventors have discovered that the dye dispersion formulation used in the spraying process has strong compatibility and eliminates the risk of equipment contamination. This method can be implemented independently of the conventional laundry detergent preparation process. This significantly expands the application scenarios for post-processing.

[0015] The inventors have discovered that if the dispersion does not contain additional water, there is no need for an additional drying process to remove moisture after the spraying process, which is advantageous for industrial production.

[0016] Based on the promising applications of polymer pigments in polymer pigment dispersions, the inventors have discovered that using polymer pigment dispersions, particularly polymer pigment-propylene glycol dispersions, can achieve superior performance under industrially acceptable conditions.

[0017] The present invention also provides the use of a dye dispersion in the preparation of colored laundry detergent and the colored laundry detergent prepared by the method for preparing colored laundry detergent described in the present invention. Detailed Implementation

[0018] The terminology used in this invention should be understood by those skilled in the art. For ease of understanding, the meanings of specific terms are described below. The following description is not intended to limit the scope of protection of this invention, but only represents the inventor's understanding of the relevant content at the time the invention was made.

[0019] dye dispersion The dye dispersion of the present invention is a homogeneous substance formed by dispersing water-soluble dyes in a dispersion medium.

[0020] The water-soluble dyes of the present invention are a subset of pigments / colorants, including all macromolecular or small molecule coloring substances that can dissolve in water.

[0021] In this invention, the water-soluble dye is preferably a polymeric pigment. A polymeric pigment generally refers to a colorant having at least one chromophore moiety attached to at least one oligomeric or polymeric chain, wherein said chain has at least three repeating units. The oligomeric or polymeric component can be attached to the chromophore via any suitable means, such as through covalent bonds, ionic bonds, or suitable electrostatic interactions. Typically, polymeric pigments are characterized by having absorbance in the range of about 300 nm to about 900 nm, which is measured by ultraviolet-visible spectroscopy.

[0022] Due to their manufacturing process, the molecular weight of polymer pigments is usually expressed as a molecular weight distribution. Therefore, the molecular weight of polymer pigments is usually reported as the average molecular weight determined by their molecular weight distribution.

[0023] The chromophore of a colorant is highly variable and can include compounds characteristic of dyes or pigments in the field. The actual group used will depend largely on, for example, the desired color and color fastness characteristics. The chromophore can be linked to at least one polyalkyleneoxy substituent via suitable nitrogen, oxygen, sulfur, or other linking motifs.

[0024] Examples of chromophores include nitroso, nitro, azo (including monoazo, diazo, triazo, tetraazo, polyazo, formazan, azomethyl bases and their metal complexes), 1,2-stilbene, diarylmethane, triarylmethane, xanthondal, quinoline, methine (including polymethyl), thiazole, indoleamine, indophenol, azine, thiazine, oxazine, aminoketone, hydroxyketone, anthraquinone (including anthraquinone, anthrone, anthraquinone, anthrimidine, flavanone, pinantrone, benzoantrone, perylene, perinone, naphthalenedicarboximide and other structures formally related to anthraquinone), indigo compounds (including indigo thiocyanate), phthalocyanine chromophores and mixtures thereof.

[0025] A suitable example of a polymer chain is a polyalkyleneoxy chain. The term "polyalkyleneoxy" as used herein generally refers to a molecular structure containing the following repeating units: -CH2CH2O-, CH2CH2CH2O-, -CH2CH2CH2CH2O-, -CH2CH(CH3)O-, -CH2CH(CH2CH3)O-CH2CH2CH(CH3)O-, and any combination thereof.

[0026] Typical examples of such groups that can be linked to chromophores are polyepoxides, such as polyepoxides and their copolymers. Typical polyepoxides and their copolymers that can be used to provide colorants include those made from epoxide (olefinic oxygen) monomers containing 2-20 carbon atoms, or more preferably 2-6 carbon atoms. Examples include: polyethylene oxide; polypropylene oxide; polybutane oxide; oxetanes; tetrahydrofuran; copolymers of polyethylene oxide, polypropylene oxide, and polybutane oxide; and other copolymers comprising block copolymers, wherein the majority of the polymeric substituents are polyethylene oxide, polypropylene oxide, and / or polybutane oxide. Furthermore, the average molecular weight of such polyalkoxide groups can range from about 132 to about 10,000, preferably from 176 to about 5,000.

[0027] It should be understood that since colorants are generally not chemically bonded to a carrier, the precise chemical ontology of the terminal groups on the polyalkoxy groups may be less critical, provided the correct function of the colorant is relevant to the composition. With this in mind, certain preferred colorants will be identified, in which certain terminal groups have been confirmed. This statement regarding terminal groups is not to be construed as limiting the invention in any way to its broader embodiments. According to such preferred embodiments, the colorant may be characterized as follows: R{A[(alkoxide component)] n R1] m} x Wherein R is an organic chromophore, A is the linking portion of the organic chromophore and is selected from N, O, S or CO2, the alkylene portion of the alkene group contains about 2 to about 4 carbon atoms, n is an integer from 2 to about 230, m is 1 when A is O, S, or CO2, and m is 1 or 2 when A is N, x is an integer from 1 to 5, and the product of n multiplied by x multiplied by m (nmx) is 2 to about 230, and R1 is selected from one of the following: And the sulfonates and sulfates of each member of the group, wherein R2 is H, an alkyl group containing up to about 20 carbon atoms, or a carboxyl-terminated alkyl group containing up to about 20 carbon atoms, j and k are OH, OM, or OR3, wherein M is a cationic moiety of an alkali metal, alkaline earth metal, transition metal (e.g., nickel), or ammonium, and R3 is an alkyl group containing up to about 20 carbon atoms.

[0028] The oligomer can be any suitable ingredient, including but not limited to oligomers selected from: (i) containing at least three oligomers selected from C2-C. 20 (ii) oligomers of monomers or repeating units of alkoxide groups, glycidol groups, and glycidyl groups; and (ii) aromatic or aliphatic oligoesters conforming to structure (I): And combinations of (iii), (i), and (ii). In structure (I), R2 and R3 are independently selected from hydrogen and C1-C. 10 Alkyl, f is an integer between 1 and 10, including 1 and 10, and g is any positive integer or fraction between 1 and 20, including 1 and 20. Those skilled in the art will understand that suitable values ​​for g include both integers and fractions because the length of the oligomeric component on a single polymeric pigment molecule is variable. Therefore, for a given sample or set of polymeric pigment molecules, the value of g represents the average length of the ester chain. In some embodiments, the polymeric pigment may include one or more oligomeric components consisting of three or more ethylene oxide monomer groups.

[0029] Exemplary polymeric pigments include Liquidint ® Polymer pigments and Palmer ® Polymer pigments, wherein the polymer pigment Liquidint ® It is the preferred option.

[0030] All of these polymeric pigments are available from Milliken Chemical Company, a subsidiary of Milliken Corporation located in Spartanburg, South Carolina. ® Polymer pigments are characterized by being water-soluble and non-staining colorants. They are widely used in laundry detergents, fabric softeners, and other consumer and industrial cleaning products. ® Polymer pigments are typically glossy liquid colorants that exhibit excellent solubility in water, compatibility with other chemicals present in their end-use formulations, and ease of handling. ® Polymer pigments can be used to provide color in both aqueous and solid systems. ®The unique polymerization properties of polymer pigments provide lower staining intensity for skin, textiles, hard surfaces, equipment, and more.

[0031] Palmer ® Polymer pigments are liquid colorants specifically developed for washable applications, such as in markers, paints, and other art products. They are free of heavy metals, non-toxic, and exhibit excellent non-staining properties on skin, fabrics, and other surfaces. Palmer ® Polymer pigments have excellent compatibility with water-based inks and provide vibrant colors.

[0032] The dyes within the scope of this invention may also be one or more colorants selected from the following categories that are suitable for use as colorants in color particles: acid dyes, basic dyes, direct dyes, solvent dyes, vat dyes, mordant dyes, indigo dyes, reactive dyes, disperse dyes, sulfur dyes, fluorescent dyes, natural colorants, etc.

[0033] In some embodiments of the present invention, the water-soluble dye accounts for 0-95% by weight in the dye dispersion, wherein the weight percentage is based on the total weight of the dye dispersion. In some preferred embodiments, the water-soluble dye accounts for 5-40% by weight in the dispersion, more preferably 10-20%. This content range imparts a wide color gamut to the dye dispersion, allowing for a wider range of color concentrations in the colored laundry detergent prepared from the dye dispersion, while also maintaining a balanced viscosity, making it suitable for spraying processes in subsequent formulations.

[0034] In this invention, polyols are selected as dispersants to disperse water-soluble dyes. Preferred examples of polyols include propylene glycol and glycerol. The amount of polyol added, or its percentage content in the dye dispersion, is determined based on the selected water-soluble dye. When a water-soluble dye with a wide solubility range is selected, the dispersant content range can be wider.

[0035] The inventors have discovered that controlling the viscosity of the aforementioned dye dispersion is important for the spraying process and even the entire post-production formulation process of colored laundry detergent. Considering factors such as dyeing performance and dispersion concentration, the inventors have found that a viscosity range of no more than 80 mPa·s is preferred. Taking into account the influence of pigment concentration in the dye dispersion, the requirements of the spraying process, and the effect of temperature on viscosity, a viscosity range of no more than 60 mPa·s is preferred, and 10 to 60 mPa·s is particularly preferred. For polymer pigment dispersions, a further preferred viscosity range is 20 to 40 mPa·s.

[0036] In one embodiment of the present invention, the dye dispersion does not contain surfactants or water. The reason for this exclusion is that the inventors have discovered that polyols exhibit excellent dispersion performance for water-soluble dyes; in this case, there is no need to add surfactants or water to improve the dispersion of the system, and the dye dispersion provides better formulation flexibility.

[0037] In a preferred embodiment of the invention, the dye dispersion is a polymer pigment-propylene glycol dispersion with a viscosity of 10-60 mPa·s, wherein the polymer pigment has a weight percentage of 0.01-40%.

[0038] Methods for preparing colored laundry detergent The method for preparing colored laundry detergent in this invention includes preparing a dye dispersion as described above and uniformly spraying the dye dispersion onto a laundry detergent base powder. The laundry detergent base powder and its preparation method, as well as the operational steps and processes involved in preparing the dye dispersion of this invention, are known in the art. The method of uniformly spraying the dye dispersion onto the base powder includes using industrial nozzles, atomizers, and other dispersing equipment to coat the liquid dispersion onto the outer surface of the laundry detergent base powder.

[0039] Based on the inventors' discovery that the dye dispersion of the present invention has the above-mentioned characteristics, especially the excellent balance between good color performance and viscosity, the method for preparing colored laundry detergent in the present invention was developed.

[0040] In one embodiment of the present invention, since the dye dispersion used does not contain water or surfactant, no additional drying process is required to remove moisture after the dye dispersion is uniformly sprayed onto the laundry detergent base powder, which simplifies the process and effectively reduces the cost of industrial production.

[0041] In a preferred embodiment of the present invention, the dye dispersion used is a polymer pigment-propylene glycol dispersion with a viscosity of 10-60 mPa·s, wherein the polymer pigment has a weight percentage of 0.01-40%.

[0042] Example The following embodiments are provided to illustrate the content of the present invention and to further understand the invention. These embodiments are not intended to limit the scope of protection of the present invention in any way.

[0043] Experiment I: Preparation of dye dispersions Prepare sufficient dye dispersions according to the weight percentages in Table 1, and set aside for use.

[0044] Table 1: Composition of dye dispersions prepared in the examples and comparative examples A1, A3, A5, A7, A9, and A11 are all dye dispersions using propylene glycol as the dispersion medium. During preparation, water-soluble dyes such as Fast Blue (FBL), Acid Red 52, and Tartrazine exhibit poor dispersibility at concentrations of 20% or 40%, resulting in a paste-like consistency in the water-soluble dye mixture. Therefore, the concentration of traditional water-soluble dyes is adjusted accordingly to 2% or 4%. However, at weight percentages of 20% or even 40%, Liquidint… ® The polymer pigments exhibit good dispersion.

[0045] B1, B3, B5, B7, B9, and B11 are all dye dispersions using AOE9 (a commercially available nonionic surfactant) as the dispersion medium. Water-soluble dyes such as Fast Blue (FBL), Acid Red 52, and Tartrazine cannot be uniformly dispersed at concentrations of 2% or 4% to form a homogeneous substance, exhibiting unacceptable dispersion performance; however, at 20% and 40% by weight, Liquidint… ® The polymer pigment exhibits good dispersibility.

[0046] Experiment II: Performance Evaluation of Dye Dispersions II-1. Viscosity Comparison Test between Traditional Water-Soluble Dye Dispersions and Polymer Pigment Dispersions At room temperature, propylene glycol dispersions of different dyes at a concentration of 5% were prepared, and their viscosity was tested. The summarized data are shown in Table 2.

[0047] Table 2: Comparison of concentrations of several traditional water-soluble dye-propylene glycol dispersions and polymer pigment-propylene glycol dispersions at 5% concentration Traditional water-soluble dye dispersions cannot be well dispersed in propylene glycol at a concentration of 6%. Therefore, the limiting concentration at which traditional water-soluble dyes can be dispersed was chosen as the viscosity test concentration. As shown in the table above, at a concentration of 5%, the viscosity of all colors is... ® Propylene glycol dispersions all exhibited significantly lower viscosity. Increased viscosity increases the propulsion burden on mass transfer units in chemical production, leading to increased energy consumption and hindering production. Therefore, Liquidint ® It has greater potential in post-processing compared to traditional water-soluble dyes.

[0048] II-2. Comparative test of viscosity of polymer pigment dispersions at different concentrations Prepare different liquidins with weight percentages of 5%, 10%, 20% and 40% respectively. ® The viscosity data of the propylene glycol dispersion is summarized in Table 3.

[0049] Table 3: Several Liquidins at different concentrations ® -Propylene glycol dispersion viscosity data In each Liquidint ® In polymer pigment-propylene glycol dispersions, the dispersion viscosity decreases with increasing polymer pigment concentration. When the polymer pigment concentration reaches 40%, the dispersion viscosity drops to approximately 20 mPa·s. Taking into account the trends in concentration and the effect of temperature on the viscosity of the substance, the viscosity range of the polymer pigment dispersion is 10–60 mPa·s at concentrations of 0.01%–40%.

[0050] Considering the excellent dispersion performance of polymer pigments in propylene glycol and other polyols, and the viscosity reduction that occurs with increasing concentration, Liquidint is a suitable choice for preparing colored laundry detergents via post-compounding processes. ® Polymer pigments can improve the color performance of colored laundry detergents while reducing the viscosity of the pigment dispersion used for spraying. This is beneficial for improving the quality of colored laundry detergents and reducing industrial production costs.

[0051] II-3. Equipment staining of dye dispersions (1) Take 2 ml of each of the four dispersions A5, A6, A9 and A10 and drop them onto four clean 304 stainless steel trays respectively. (2) Let stand overnight; (3) Clean and wipe the four stainless steel trays with clean water and a soft cloth, and observe the changes in the appearance of the metal surface.

[0052] Comparing the staining of four dispersions (A5, A6, A9, and A10) on stainless steel pallets, the pallets supported by A6 and A10 remained clean after cleaning, the pallets supported by A9 retained a slight yellow residue, and the pallets supported by A5 showed a more obvious color change.

[0053] It can be seen that the Liquidint corresponding to A6 and A10 ® Polymer pigment and dye dispersions have lower equipment contamination and equipment damage.

[0054] Experiment III: Preparation and Color Evaluation of Colored Laundry Detergent III-1. Preparation of Colored Laundry Detergent (1) Prepare 500g of colored laundry detergent according to the formula shown in Table 4, wherein the dye dispersion used is the dye dispersion A1~A12 involved in this invention (the laundry detergent base powder used is a commercially available product).

[0055] Table 4: Composition of Colored Laundry Detergent in Examples (2) Weigh out the appropriate amount of laundry detergent and place it in the rotating coating device. Turn on the drum and adjust it to rotate at a constant speed of 40-50 RPM. Weigh out the appropriate amount as needed and seal it for later use. (3) Under laboratory conditions, the corresponding dye dispersion was atomized at a pressure of 0.20 MPa and sprayed into the laundry detergent base powder in a rotary mixer, and then fully mixed in the rotary mixer; (4) A total of 500g of each of C1~C12 colored laundry detergents were prepared and sealed in jars for later use.

[0056] Given that when AEO9 is used as the dispersion medium, water-soluble dyes such as FBL, Acid Red 52, and Lemon Yellow cannot be evenly dispersed at a concentration of 2% or 4% to form a homogeneous substance, they cannot be spread out, and therefore cannot be further used to prepare colored laundry detergent.

[0057] III-2. Evaluation of the color performance of colored laundry detergents Comparing the color performance of the four groups of colored laundry detergents, C1, C2, C3 and C4, it can be found that C2 and C4 exhibit a significantly deeper blue compared to C1 and C3; even C4 (2.5g), which uses a lower amount of dye dispersion, has a noticeably deeper blue compared to C1 (5g), which uses a higher amount of dye dispersion.

[0058] It is evident that, when using the same mass of dye dispersion, the colored laundry detergent prepared using the dye dispersion of the present invention can achieve a wider range of color depths, resulting in superior color performance.

Claims

1. A dye dispersion for preparing colored laundry detergent, characterized in that: The mixture comprises a polyol and a water-soluble dye dispersed therein, wherein the water-soluble dye comprises 0.01-40% by weight, the viscosity of the dye dispersion is 10-60 mPa·s, and the water-soluble dye is a polymer pigment having the following structure: R{A[(alkoxide component)] n R1] m } x Where R is an organic chromophore, A is the linking portion of the organic chromophore and is selected from N, O, S or CO2, the alkylene portion of the alkene group contains 2 to 4 carbon atoms, n is an integer from 2 to 230, m is 1 when A is O, S or CO2, and m is 1 or 2 when A is N, x is an integer from 1 to 5, and the product of n, x and m is 2 to 230, and R1 is selected from one of the following: And the sulfonates and sulfates of each member in the group, wherein R2 is H, an alkyl group containing up to 20 carbon atoms or a carboxyl-terminated alkyl group containing up to 20 carbon atoms, j and k are OH, OM or OR3, wherein M is a cationic moiety of an alkali metal, alkaline earth metal, transition metal or ammonium, and R3 is an alkyl group containing up to 20 carbon atoms.

2. The dye dispersion according to claim 1, characterized in that: The transition metal is nickel.

3. The dye dispersion according to claim 1, characterized in that: The surfactant content in the dye dispersion is less than 1%.

4. The dye dispersion according to claim 1, characterized in that: The polyol is propylene glycol or glycerol.

5. The dye dispersion according to claim 1, characterized in that: The polyol is propylene glycol or glycerol, and the surfactant content is less than 1%, wherein the polymer pigment has a weight percentage of 5-40%, and the viscosity of the dye dispersion is 20-40 mPa·s.

6. Use of the dye dispersion according to any one of claims 1 to 5 in the preparation of colored laundry detergent.

7. A method for preparing colored laundry detergent, characterized in that... Includes the following steps: (1) Prepare a dye dispersion, wherein the dye dispersion comprises a polyol and a water-soluble dye dispersed therein; (2) Spray the dye dispersion evenly onto the laundry detergent base powder; The dye dispersion contains 0.01% to 40% water-soluble dye by weight, has a viscosity of 10 to 60 mPa·s, and is a polymeric pigment having the following structure: R{A[(alkoxide component)] n R1] m } x Where R is an organic chromophore, A is the linking portion of the organic chromophore and is selected from N, O, S or CO2, the alkylene portion of the alkene group contains 2 to 4 carbon atoms, n is an integer from 2 to 230, m is 1 when A is O, S or CO2, and m is 1 or 2 when A is N, x is an integer from 1 to 5, and the product of n, x and m is 2 to 230, and R1 is selected from one of the following: And the sulfonates and sulfates of each member in the group, wherein R2 is H, an alkyl group containing up to 20 carbon atoms or a carboxyl-terminated alkyl group containing up to 20 carbon atoms, j and k are OH, OM or OR3, wherein M is a cationic moiety of an alkali metal, alkaline earth metal, transition metal or ammonium, and R3 is an alkyl group containing up to 20 carbon atoms.

8. The method according to claim 7, characterized in that: The transition metal is nickel.

9. The method according to claim 7, characterized in that: The surfactant content in the dye dispersion is less than 1%.

10. The method according to claim 7, characterized in that: The polyol is propylene glycol or glycerol, and the surfactant content is less than 1%, wherein the polymer pigment has a weight percentage of 5-40%, and the viscosity of the dye dispersion is 20-40 mPa·s.

11. The method according to claim 7, characterized in that: No additional drying process is included after step (2) to remove moisture.

12. Colored laundry detergent prepared by the method according to any one of claims 7 to 11.

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