Laundry condensate bead containing dye-absorbing fiber

Abstract

The invention discloses laundry gel beads containing dye-absorbing fibers, and belongs to the technical field of detergents. The laundry gel bead comprises a water-soluble outer film, a washing liquid, a solid fragrance retention agent and a dye absorption fiber, wherein the dye absorption fiber adopts a double-layer structure design: the bottom layer is a high-density cross-linked cellulose layer, and the surface layer is a cation modified sponge structure layer; particularly, a tea polyphenol-iron ion chelate is adopted as a cross-linking agent to replace a traditional borate compound, so that non-toxic cross-linking is realized; according to the invention, the problems of poor cross-color prevention effect, difficult compression of the dye-absorbing fibers and difficult recovery after compression of the laundry condensate beads are solved, the laundry condensate beads containing the dye-absorbing fibers can achieve the effects of washing, color protection, fragrance retention and cross-color prevention while avoiding the aquatic toxicity of a borate cross-linking agent, and the laundry condensate beads conform to the development trend of environmental friendliness.

Description

Technical Field

[0001] The present invention relates to the technical field of detergents, and in particular to laundry beads containing color-absorbing fibers and a preparation method thereof. Background Art

[0002] Laundry detergent beads, a new generation of concentrated detergents, are widely popular in the market due to their ease of use, accurate metering, and excellent cleaning results. To address the issue of color bleed during the mixed washing process, existing technologies often incorporate color bleed inhibitors into laundry detergent beads. However, this presents the following challenges: The anti-color transfer effect of anti-color transfer laundry beads depends entirely on the formula concentration of the beads. The content of anti-color transfer agent that can be contained in a bead is relatively low. For severely discolored clothes, its protective ability may be insufficient, and there is still a risk of color transfer. The laundry beads adopt a multi-cavity design and the anti-color transfer agent is independently encapsulated. This design can maximize the protection of the anti-color transfer agent's activity and optimize its release timing. However, during long-term storage, it will gradually dissolve and diffuse into the bead liquid, affecting the use effect. For the sake of beauty, laundry beads are mostly colorful. During storage or use, the anti-color transfer agent will first adsorb the dye of the beads, further reducing the anti-color transfer effect on clothes.

[0003] Existing spunlace nonwoven towels, which have excellent water absorption, are pressed into a round cake shape through heat or vacuum compression. Water permeates through them, increasing their volume and allowing them to expand rapidly. Color-absorbing fibers, which preferentially absorb dye molecules over water, are modified with cations (such as glycidyltrimethylammonium chloride) and modified silicone oil to create a dye-repellent coating, making them hydrophobic. However, these fibers are difficult to compress and can easily expand during storage or become difficult to expand when compressed too tightly.

[0004] Therefore, there is an urgent need to develop a new type of color-absorbing fiber structure that can be easily compressed, avoid the use of toxic cross-linking agents, and maintain excellent color-absorbing performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a laundry detergent bead containing color-absorbing fibers, which solves the technical problems existing in traditional laundry detergent bead through an innovative double-layer structure design and an environmentally friendly cross-linking system.

[0006] To achieve the above object, the technical solution adopted by the present invention is: Laundry detergent beads containing color-absorbing fibers include a water-soluble outer membrane, detergent, and color-absorbing fibers. The key innovations are: S1: Double-layer structure design, the color-absorbing fiber adopts a composite structure of a bottom high-density cross-linked cellulose layer and a surface cationic modified sponge structure layer. Preparation of the bottom layer: The bamboo fiber pulp is immersed in a mixed aqueous solution of citric acid and sodium hypophosphite at a temperature of 35-45°C for 20-40 minutes, added to the reactor, and hot pressed at 115-125°C (pressure 8-12MPa, time 8-12min); after being removed, it is washed with deionized water until neutral, and dried at 60-70°C to obtain a 0.5mm sheet; Preparation of the surface layer: EPTAC and NaOH are dissolved in ethanol, and then ultrasonically dissolved at 40-50°C to prepare a modified solution. The melamine sponge is immersed in the modified solution and reacted at 65-75°C for 3-5 hours (amplitude 50-70Hz), then rinsed with 40-50°C ethanol 3-5 times, and vacuum dried at 55-65°C.

[0007] S2: An environmentally friendly cross-linking system uses tea polyphenol-iron ion chelate instead of traditional borate cross-linkers. Tea polyphenols are stirred and dissolved in a buffer solution at 40-60°C (stirring rate 500-800 rpm), with the pH precisely controlled at 5.0-5.5. The iron ion chelate solution is added dropwise while maintaining positive nitrogen pressure, and the reaction is shaken at a constant temperature. The parameters are set as follows: temperature 45-55°C, duration 1.5-2.5 hours, amplitude 150-250 rpm, to obtain a tea polyphenol-iron ion chelate solution. PDMS aqueous emulsion is added, and the mixture is stirred at 300 rpm for 30 minutes at a constant temperature of 45°C to obtain a tea polyphenol-iron ion chelate solution containing PDMS.

[0008] S3: Compression molding technology, through high temperature and high pressure compression treatment, the double layer materials are tightly combined. Spraying a tea polyphenol-iron ion chelate solution with a mass fraction of 8-12% (containing 0.05-0.15% PDMS) and a spraying amount of 150-250g / m 2 , and then solidify at 75-85°C for 25-35min, with a compression axial pressure of 10-20MPa for 1-2min; then heat-set at 55-65°C under pressure holding for 15-25min; non-ionic surfactant 35-65%, anionic surfactant 10-30%, flavor 0.1-10%, enzyme preparation 1-5%, chelating agent 1.5-2.5%, pH regulator 0.3-1%, structural stabilizer 1-3%, cosolvent 5-25%, deionized water 3-10%, non-ionic color retaining agent 0.3-7%, preservative 0.2-0.6%, polyvinyl alcohol (PVA, degree of polymerization 1700-1800, alcoholysis degree 88%) is used to form a thick film by a casting method, and finally the color-absorbing fiber, detergent, and solid fragrance agent are respectively encapsulated in the polyvinyl alcohol film in the water-soluble outer film.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. Easy to compress, sensitive to reaction, low resilience rate.

[0010] 2. Completely avoid the use of toxic borate crosslinking agent, in line with environmental requirements.

[0011] 3. Double-layer structure synergistic effect, color absorption capacity increased by 30-50mg / g. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is the flow chart of the preparation method of laundry condensate beads containing color absorption fibers.

[0013] Figure 2 is the data graph of color absorption capacity of laundry condensate beads containing color absorption fibers.

[0014] Figure 3 is the schematic diagram of laundry condensate beads containing color absorption fibers, solid fragrance, and laundry liquid.

[0015] Figure 4 is the physical picture of color absorption fibers before aging prepared by example 1 and comparative example 1.

[0016] Figure 5 is the physical picture of color absorption fibers after aging prepared by example 1 and comparative example 1.

[0017] Figure 6 is the fitting graph of absorbance and active mixed dyes.

[0018] Figure 7 is the fitting graph of absorbance and direct mixed dye concentration. DETAILED DESCRIPTION

[0019] The following examples further explain and illustrate the technical solutions of the present application. It is particularly pointed out that each specific embodiment is a specific embodiment and explanation of the technical solution, and should not be regarded as a limitation on the protection scope of the present application. Those skilled in the art still have the right to modify the technical solutions of these examples, to equivalently replace part or all of the technical features, and these modifications or replacements do not change the essence of the corresponding technical solution, and do not make the essence of the corresponding technical solution deviate from the scope of the technical solution described in the present application.

[0020] The present application proposes laundry condensate beads containing color absorption fibers and a preparation method thereof, the raw materials used are: tea polyphenols (EGCG≥98%), iron ion chelate solution (chelating agent: α-sodium glucoheptonate), PDMS water emulsion, sodium acetate buffer (pH=5.2±0.1), bamboo fiber pulp (polymerization degree 600-700, α cellulose≥90%), citric acid (food grade, purity≥99.5%), sodium hypophosphite (NaH2PO2, analytical pure), melamine sponge (density 8mg / cm 3, glycidyltrimethylammonium chloride (EPTAC, purity≥95%), sodium hydroxide (NaOH, analytical pure), anhydrous ethanol (industrial grade), fatty alcohol polyoxyethylene ether, sodium dodecylbenzenesulfonate, essence, protease, amylase, EDTA-4Na, polyvinylpyrrolidone, propylene glycol, deionized water, modified silicone oil, sodium benzoate. As shown in the accompanying Figure 1 The laundry condensation beads containing the color-adsorbing fibers and the preparation method thereof are shown in the accompanying 1. Preparation of color-adsorbing fibers 1.1 Proportioning of base layer materials The addition amount of citric acid is 6-10% of the bamboo fiber pulp, the addition amount of sodium hypophosphite is 1.5-2.5% of the bamboo fiber pulp, and the mass-to-volume ratio of the bamboo fiber pulp to deionized water is 1:4 to 1:6.

[0021] 1.2 Preparation The bamboo fiber pulp is immersed in a mixed aqueous solution of citric acid and sodium hypophosphite at a temperature of 35-45°C for 20-40 min, added to a reaction kettle, and subjected to hot pressing at 115-125°C (pressure 8-12 MPa, time 8-12 min); after removal, washed with deionized water until neutral, and dried at 60-70°C to obtain a 0.5 mm sheet.

[0022] 1.3 Proportioning of surface layer materials The density of the melamine sponge is 6-10 mg / cm 3 The concentration of ethanol is 85-95%, the addition amount of EPTAC is 15-25% of the volume fraction of ethanol, and the addition amount of NaOH is 3-6% of the volume fraction of ethanol.

[0023] 1.4 Cationic modification of surface layer EPTAC and NaOH are dissolved in ethanol, and then ultrasonic dissolution is performed at 40-50°C to prepare a modification solution, the melamine sponge is immersed in the modification solution, oscillation reaction is performed at 65-75°C for 3-5 h (amplitude 50-70 Hz), and then the sponge is rinsed with 40-50°C ethanol for 3-5 times and vacuum dried at 55-65°C.

[0024] 2. Preparation of tea polyphenol-iron ion chelate 2.1 Proportioning The molar ratio of the iron ion chelate to tea polyphenol is 1:2 to 1:3.

[0025] 2.2 Preparation Tea polyphenols are stirred and dissolved in a buffer solution at 40-60°C (stirring rate 500-800 rpm), and the pH is precisely controlled at 5.0-5.5; an iron ion chelate solution is added dropwise while maintaining positive nitrogen pressure, and the reaction is oscillated at a constant temperature with the following parameters set: temperature 45-55°C, duration 1.5-2.5 hours, amplitude 150-250 rpm; PDMS aqueous emulsion is added, and the mixture is stirred at 300 rpm for 30 minutes at a constant temperature of 45°C to obtain a tea polyphenol-iron ion chelate solution containing PDMS.

[0026] 3. Compression composite molding 3.1 Ratio between double-layer composite and cross-linked layers: bottom layer thickness 0.4-0.6mm, surface layer thickness 2.5-3.5mm, bottom layer to surface layer area ratio 1:5 to 1:7. Spraying mass percentage concentration of 8-12% tea polyphenol-iron ion chelate solution (containing 0.05-0.15% PDMS), spraying amount 150-250g / m 2 , and then cure at 75-85°C for 25-35 minutes.

[0027] 3.2 Characterization of supercompression The compression axial pressure is 10-20 MPa for 1-2 minutes, and then the temperature is controlled at 55-65°C under the pressure holding state for 15-25 minutes before heat setting.

[0028] 4. Packaging of laundry beads 4.1 Preparation of washing solution 35-65% of non-ionic surfactant, 10-30% of anionic surfactant, 0.1-10% of flavor, 1-5% of enzyme preparation, 1.5-2.5% of chelating agent, 0.3-1% of pH regulator, 1-3% of structural stabilizer, 5-25% of cosolvent, 3-10% of deionized water, 0.3-7% of non-ionic color retaining agent, and 0.2-0.6% of preservative are prepared into a washing liquid.

[0029] 4.2 Preparation of water-soluble film The film is made of polyvinyl alcohol (PVA, degree of polymerization 1700-1800, degree of alcoholysis 88%) by a casting method.

[0030] 4.3 Encapsulation The color-absorbing fiber, washing liquid and solid fragrance-retaining agent are respectively encapsulated in the polyvinyl alcohol film in the water-soluble outer film by using a bead forming machine, and then heat-sealed to form the film.

[0031] Example 1 The preparation method of laundry beads containing color-absorbing fibers is as follows: The raw materials include: tea polyphenols (EGCG ≥ 98%), iron ion chelate solution (chelating agent: sodium α-glucoheptonic acid), PDMS aqueous emulsion, sodium acetate buffer (pH = 5.2 ± 0.1), bamboo fiber pulp (polymerization degree 600-700, α cellulose ≥ 90%), citric acid (food grade, purity ≥ 99.5%), sodium hypophosphite (NaH2PO2, analytical grade), melamine sponge (density 8 mg / cm 3 , PPI 80), glycidyltrimethylammonium chloride (EPTAC, purity ≥95%), sodium hydroxide (NaOH, analytical grade), anhydrous ethanol (industrial grade), fatty alcohol polyoxyethylene ether, sodium dodecylbenzenesulfonate, flavor, protease, amylase, EDTA-4Na, polyvinyl pyrrolidone, propylene glycol, deionized water, modified silicone oil, sodium benzoate.

[0032] S1: The amount of citric acid added is 10% of the bamboo fiber pulp, the amount of sodium hypophosphite added is 2.5% of the bamboo fiber pulp, and the mass-to-volume ratio of bamboo fiber pulp to deionized water is 1:5; the temperature is controlled at 40°C, and the bamboo fiber pulp is immersed in a mixed aqueous solution of citric acid and sodium hypophosphite for 30 minutes, added to a reactor, and hot pressed at 120°C (pressure 10 MPa, time 10 minutes); after taking out, it is washed with deionized water until neutral, and dried at 60°C to obtain a 0.5 mm sheet.

[0033] Melamine sponge density 10mg / cm 3 , ethanol concentration is 95%, the amount of EPTAC added is 25% of the volume fraction of ethanol, and the amount of NaOH added is 6% of the volume fraction of ethanol; EPTAC and NaOH are dissolved in ethanol, and then ultrasonically dissolved at 40°C to prepare a modification solution, the melamine sponge is immersed in the modification solution, oscillated at 70°C for 4h (amplitude 50Hz), then rinsed with ethanol at 40°C for 5 times, and vacuum dried at 60°C.

[0034] S2: The molar ratio of iron ion chelate: tea polyphenol is 1:2.5. Tea polyphenol is stirred and dissolved in a 50°C buffer solution (stirring rate 500-800 rpm), and the pH is precisely controlled at 5.2; the iron ion chelate solution is added dropwise while maintaining positive nitrogen pressure, and the reaction is oscillated at a constant temperature. The parameters are set as follows: temperature 50°C, duration 2h, amplitude 200rpm, PDMS aqueous emulsion is added, and stirring is carried out at 300rpm for 30min at a constant temperature of 45°C to obtain a tea polyphenol-iron ion chelate solution containing PDMS.

[0035] S3: interlayer ratio: bottom layer thickness 0.5mm, surface layer thickness 3.0mm, bottom layer to surface layer area ratio 1:6. Spray 12% tea polyphenols-iron ion chelate solution (containing 0.12% PDMS, spraying amount 220g / m 2), and then cured at 80°C for 30 minutes. The compression axial pressure is 18MPa, and the duration is 2min; then the temperature is controlled at 60°C under the pressure holding state, and the duration is 20min for heat setting; 45% fatty alcohol polyoxyethylene ether, 15% sodium dodecylbenzene sulfonate, 7% essence, 2% protease, 1% amylase, 2% EDTA-4Na weight, 0.5% citric acid, 2% polyvinyl pyrrolidone, 20% propylene glycol, 4.6% deionized water, 0.5% modified silicone oil, 0.4% sodium benzoate, mixed to prepare detergent, and finally the color-absorbing fiber, detergent, and solid fragrance agent are respectively encapsulated in the polyvinyl alcohol film in the water-soluble outer film. The schematic diagram of the laundry beads is shown in the attached figure. Figure 3 shown.

[0036] Example 2 The composition and preparation process are the same as in Example 1, except that: In the preparation process S1, the amount of citric acid added is 8% of the bamboo fiber pulp, the amount of EPTAC added is 20% of the volume fraction of ethanol, and the other compositions are the same.

[0037] The PDMS content in the tea polyphenol-iron ion chelate solution in S3 of the preparation process is 0.10%, and the other compositions are the same.

[0038] Example 3 The composition and preparation process are the same as in Example 1, except that: In the preparation process S1, the amount of citric acid added is 6% of the bamboo fiber pulp, the amount of EPTAC added is 18% of the volume fraction of ethanol, and the other compositions are the same.

[0039] The PDMS content in the tea polyphenol-iron ion chelate solution in S3 of the preparation process is 0.08%, and the other compositions are the same.

[0040] Example 4 The composition and preparation process are the same as in Example 1, except that: In the preparation process S1, the amount of citric acid added is 9% of the bamboo fiber pulp, the amount of EPTAC added is 22% of the volume fraction of ethanol, and the other compositions are the same.

[0041] The PDMS content in the tea polyphenol-iron ion chelate solution in S3 of the preparation process is 0.13%, and the other compositions are the same.

[0042] Comparative Example 1 The composition and preparation process are the same as in Example 1, except that: In the preparation process S2, the tea polyphenol-iron ion chelate spray coating is eliminated and only pure PDMS solution is used, while the other compositions are the same.

[0043] Comparative Example 2 The composition and preparation process are the same as in Example 1, except that: In S1 of the preparation process, borax is used instead of citric acid and sodium hypophosphite, and the other compositions are the same.

[0044] Comparative Example 3 The composition and preparation process are the same as in Example 1, except that: In the preparation process S3, only a single bottom layer material (thickness 3.5 mm) is used without a surface cationic modified sponge, and the other steps are the same.

[0045] Comparative Example 4 The composition and preparation process are the same as in Example 1, except that: In the preparation process S3, only cationic modified melamine sponge (thickness 3.5 mm) was used without bamboo fiber bottom layer, and the other steps were the same.

[0046] The stability test of the color-absorbing fibers in Example 1 and Comparative Example 1 was conducted: the compressed color-absorbing fiber samples were placed in a 30°C / 70% RH environment for 7 days. After the samples returned to room temperature, the state of the samples was observed. Figure 4 With attached Figure 5 As shown, attached Figure 4 The upper part is Example 1, and the lower part is Comparative Example 1; Figure 5 The treated color-absorbing fibers are shown in FIG1 , with the upper half being Example 1 and the lower half being Comparative Example 1.

[0047] Based on the preparation methods of laundry beads containing color-absorbing fibers in Examples 1-4 and Comparative Examples 1-4, dye adsorption capacity was tested: 1.000g (accurate to 0.001g) of Reactive Red 3BSN, Reactive Blue B, Reactive Black WNN, Direct Blended Ruby D-BLL, and Direct Blended Blue D-3GL dyes were weighed on an analytical balance, each dissolved in 250mg / kg hard water, and then transferred to a 1000mL volumetric flask, fixed to 1000mL, and shaken for use. The three reactive dye solutions were mixed in a ratio of 1:1:1 to form a 1g / L reactive dye mixed stock solution. The two direct dye solutions were mixed in a ratio of 1:1 to form a 1g / L direct dye mixed stock solution. 100mL of the mixed dye stock solution was transferred to a 1000mL volumetric flask with a pipette (the two mixed dye test solutions needed to be prepared separately), diluted to the mark with 250mg / kg hard water, and shaken.

[0048] Take 1.0mL, 2.0mL, 4.0mL, 6.0mL, 8.0mL, 10.0mL, and 12.0mL of the 1g / L mixed dye stock solution and place it in a 100mL volumetric flask, dilute to the mark with hard water, and shake well. At (25±2)°C, use a spectrophotometer (UV-2600i Shimadzu UV-visible spectrophotometer) with a 10mm cuvette and hard water as a reference to measure the absorbance of the prepared series of solutions (the wavelength is set to 550nm for the active mixed dye and 565nm for the direct mixed dye). Plot a standard curve for the two mixed dyes with the series solution concentration (mg / L) as the horizontal axis and the absorbance as the vertical axis. The linear correlation coefficient r is used. 2 ≥0.99, as attached Figure 6 With attached Figure 7 shown.

[0049] Place the compressed color-absorbing fiber in pure water to allow it to expand and recover naturally. After drying, cut it into 1 cm × 1 cm small pieces for later use.

[0050] Weigh 0.100 g of the pretreated sample (accurate to 0.001 g) and record the weight, m0. Pipette 100 mL of the mixed dye test solution (the two mixed dyes need to be measured separately) into a 150 mL beaker. Set the magnetic stirrer to 120 rpm and insert a magnet. Stir at (25 ± 2)°C for 1 minute. Quickly add the sample and start the timer. After 20 minutes, stop stirring and aspirate approximately 25 mL of the solution. Measure the absorbance of the solution and use the absorbance to determine the concentrations of the two mixed dyes from the standard curve.

[0051] The preparation method of the laundry beads containing color-absorbing fibers in Comprehensive Examples 1-4 and Comparative Examples 1-4, the compression permanent deformation rate, and the rebound rate within 5s refer to the standard GB / T 1041-2008 "Plastic Compression Performance Standard", and the environmental protection reference standard GB / T26396-2019 "Safety Technical Specifications for Detergents".

[0052] The above test results are shown in Table 1, Table 2, and Table 3.

[0053] Table 1 Dye adsorption amount table of Examples 1-4 and Comparative Examples 1-4.

[0054] Table 2 Performance comparison of Examples 1-4 and Comparative Examples 1-4 From the above, it can be seen that in Examples 1-4, citric acid and sodium hypophosphite are used to realize cellulose crosslinking, and EPTAC modification provides cationic sites, and the whole process is free of boron, thereby avoiding the harm of borate. Although the compression permanent set of Comparative Example 2 is low, the use of borax does not meet the environmental protection requirements; in Example 1, the high-PDMS tea polyphenol-iron ion chelate is strengthened to form an interpenetrating network with PDMS, and the hydrophobic polymer is physically anchored.

Claims

1. Laundry detergent beads containing color-absorbing fibers, characterized in that: It includes a water-soluble outer membrane, a detergent, a solid fragrance agent and color-absorbing fibers; the color-absorbing fibers are a double-layer structure, with a bottom layer being a high-density cross-linked cellulose layer and a surface layer being a cationic modified sponge structure layer; the high-density cross-linked cellulose layer uses tea polyphenol-iron ion chelate as a cross-linking agent.

2. The laundry detergent beads containing color-absorbing fibers according to claim 1, characterized in that: The color absorption capacity of laundry beads is increased by 30 to 50 mg / g.

3. The laundry detergent beads containing color-absorbing fibers according to claim 1, characterized in that: The double-layer structure has an initial bottom layer thickness of 0.4 to 0.6 mm, an initial surface layer thickness of 2.5 to 3.5 mm, and an area ratio of the bottom layer to the surface layer of 1:5 to 1:

7.

4. The laundry detergent beads containing color-absorbing fibers according to claim 1, characterized in that: In the tea polyphenol-iron ion chelate, the molar ratio of the iron ion chelate to the tea polyphenol is 1:2 to 1:3, and the tea polyphenol-iron ion chelate contains 0.05 to 0.15% of PDMS.

5. The laundry detergent beads containing color-absorbing fibers according to claim 1, characterized in that: The color-absorbing fibers are compressed or folded into a circular, flower-shaped, polygonal, multi-faceted, or irregular pattern and then encapsulated into a separate cavity of the condensation bead.

6. The laundry detergent beads containing color-absorbing fibers according to claim 1, characterized in that: The washing liquid comprises, by mass fraction, 35-65% of a nonionic surfactant, 10-30% of anionic surfactant, 0.1-10% of essence, 1-5% of an enzyme preparation, 1.5-2.5% of a chelating agent, 0.3-1% of a pH regulator, 1-3% of a structural stabilizer, 5-25% of a cosolvent, 3-10% of deionized water, 0.3-7% of a nonionic color retaining agent, and 0.2-0.6% of a preservative.

7. The laundry detergent beads containing color-absorbing fibers according to claim 1, characterized in that: The water-soluble outer film is a polyvinyl alcohol film with a thickness of 20 to 50 μm.

8. A laundry detergent bead containing color-absorbing fibers according to any one of claims 1 to 7 and a method for preparing the same, characterized in that: The following steps are involved: S1: Double-layer structure design: Bamboo fiber pulp is immersed in a mixed aqueous solution of citric acid and sodium hypophosphite at a temperature of 35-45°C for 20-40 minutes, then added to a reactor for hot pressing. After removal, it is washed with deionized water until neutral, and dried at 60-70°C to obtain a sheet. Surface layer preparation: EPTAC and NaOH are dissolved in ethanol, then ultrasonically dissolved at 40-50°C to prepare a modified solution. A melamine sponge is immersed in the modified solution, shaken for reaction, and then rinsed with 40-50°C ethanol 3-5 times, and vacuum dried at 55-65°C. S2: Tea polyphenols are stirred and dissolved in a buffer solution at 40-60°C, with the pH precisely controlled at 5.0-5.5; the iron ion chelate solution is added dropwise while maintaining positive nitrogen pressure, and the reaction is shaken at a constant temperature to obtain a tea polyphenol-iron ion chelate solution; PDMS aqueous emulsion is added, and the mixture is stirred at 300 rpm for 30 minutes at a constant temperature of 45°C to obtain a tea polyphenol-iron ion chelate solution containing PDMS; S3: Spray a tea polyphenol-iron ion chelate solution with a mass fraction of 8-12% on the double-layer material prepared in S1, and then cure it at 75-85°C for 25-35 minutes, with a compressive axial pressure of 10-20 MPa for 1-2 minutes, and then control the temperature at 55-65°C under the pressure holding state for 15-25 minutes to tightly combine the double-layer material; finally, encapsulate the color-absorbing fiber, detergent, and solid fragrance agent in the polyvinyl alcohol film in the water-soluble outer film respectively.

9. The laundry detergent beads containing color-absorbing fibers and the preparation method thereof according to claim 8, characterized in that: The amount of citric acid added in S1 is 6-10% of the bamboo fiber pulp, the amount of sodium hypophosphite added is 1.5-2.5% of the bamboo fiber pulp, and the mass-to-volume ratio of bamboo fiber pulp to deionized water is 1:4 to 1:6; the density of the melamine sponge in S2 is 6-10 mg / cm 3 , ethanol concentration is 85-95%, the amount of EPTAC added is 15-25% of the ethanol volume fraction, and the amount of NaOH added is 3-6% of the ethanol volume fraction.

10. The laundry detergent beads containing color-absorbing fibers and the preparation method thereof according to claim 8, characterized in that: The hot pressing described in S1 has the following parameter settings: temperature 115-125° C., pressure 8-12 MPa, and duration 8-12 min.

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