Washable watercolor pen ink and preparation method thereof

Abstract

The invention relates to the technical field of ink preparation, in particular to washable watercolor pen ink and a preparation method thereof. The washable watercolor pen ink is prepared from the following raw materials in parts by mass: 3 to 5 parts of modified dye, 8 to 10 parts of water-based polyacrylic resin emulsion, 2 to 2.5 parts of composite dispersing agent, 22 to 25 parts of humectant, 0.2 to 0.5 part of pH regulator, 5 to 7 parts of hydroxypropyl-beta-cyclodextrin, 0.2 to 0.3 part of preservative and 55 to 60 parts of deionized water. The washable watercolor pen ink has remarkable advantages in the aspects of improving dye stability, reducing skin dyeing, improving product safety and environmental friendliness and the like, and is particularly suitable for infants and school children to use.

Description

Technical Field

[0001] The present application relates to the technical field of ink preparation, and particularly relates to a washable watercolor pen ink and a preparation method thereof. Background Art

[0002] Watercolor pens are very popular painting tools for children because of their sufficient moisture, rich and bright colors. Currently, the commonly used colored pen inks in the market are oil-soluble dye-based inks, and the solvents are mainly alcohols. The handwriting written with such inks is difficult to erase when modified. Although the currently available washable watercolor inks on the market can be written on the surfaces of paper, clothes, etc. and washed clean with water, they are easily stained on the skin when used by children, and the skin cleaning effect is not good. The disadvantage of washable watercolor inks in the use process is that the skin washability is poor. After painting on the skin and washing, different degrees of ink marks will be left, and even using soap or detergent cannot achieve complete cleaning.

[0003] Chinese Patent CN201210129337.3A named "A Water-based Washable Ink" discloses a washable ink, including that the hydrophilic-lipophilic balance value (HLB) of the colorant should be at least 20, the mass content of each colorant in the system is 0.1-8%, the mass content of the polyepoxy alcohol co-cleaning agent in the system is 8-20%, the mass ratio between the polyepoxy alcohol derivative substance and the polyepoxy ethanol co-cleaning agent is about 0.2-0.45, the mass ratio of the water-soluble resin to the colorant is about 0.75-1.25, the mass content of the bactericidal and mildew-proof agent is 0.1-0.5%, and the balance is made up with water and other water-soluble solvents or their combinations. In this ink system, by adding polyepoxy alcohol polymers and their corresponding derivatives and combining them with water-soluble resins, the binding ability between the colorant and the fabric or skin surface is weakened, so that the ink marks can be directly washed clean with clear water. However, its washability still needs to be further improved. Summary of the Invention

[0004] The purpose of the present application is to provide a washable watercolor pen ink and a preparation method thereof in view of the deficiencies of the current technology. For the washable watercolor pen ink of the present application, by utilizing the cavity structure of cyclodextrin in hydroxypropyl-β-cyclodextrin, the modified dye molecules can enter the cavity for secondary coating, thereby reducing the contact with the skin and textiles. At the same time, for the prepared modified dye, the dye is wrapped by polyacrylic acid resin to form a microcapsule structure to achieve the first coating, which can largely avoid the combination of the dye and the skin, and has good re-solubility on the skin without affecting the color degree of the original color of the dye, and fully improves the washability of the dye. The composite dispersant promotes the water-based polyacrylic acid resin emulsion to wrap the secondary-coated dye molecules again, further reducing the contact between the dye and the skin and textiles, and significantly improving the washability of the ink. The washable watercolor pen ink prepared in the present application is particularly suitable for watercolor pens for infants and school-age children.

[0005] In a first aspect, the present application provides a washable watercolor pen ink, adopting the following technical solutions: A washable watercolor pen ink, by mass parts, comprises the following preparation raw materials: 3-5 parts of modified dye, 8-10 parts of aqueous polyacrylic resin emulsion, 2-2.5 parts of composite dispersant, 22-25 parts of humectant, 0.2-0.5 parts of pH regulator, 5-7 parts of hydroxypropyl-β-cyclodextrin, 0.2-0.3 parts of preservative, and 55-60 parts of deionized water.

[0006] By adopting the above technical solutions, the modified dye is encapsulated by the polyacrylic resin to form a microcapsule structure, achieving the first coating, which can largely avoid the combination of the dye and the skin, and has good re-solubility on the skin without affecting the color degree of the original color of the dye, fully improving the washability of the dye. Aqueous polyacrylic resin emulsion: This emulsion is synthesized by reaction monomers such as methyl methacrylate (MMA) and butyl acrylate (BA) and functional monomers such as acrylic acid (AA), hydroxypropyl acrylate (HPA), and glycidyl methacrylate (GMA), and has good dispersibility and film-forming properties. It can well disperse and encapsulate the modified dye, further reducing the contact between dye molecules and the skin and textiles, thereby improving the washability of the ink. The composite dispersant is used to promote the re-encapsulation of the dye molecules by the aqueous polyacrylic resin emulsion. This not only enhances the dispersibility of the dye but also further reduces the contact between dye molecules and the skin and textiles, thereby improving the washability of the ink. Humectant: The humectant plays a role in maintaining moisture in the ink formula, ensuring the stability and fluidity of the ink. At the same time, the humectant can also improve the skin affinity of the ink. The pH regulator is used to adjust the acidity and alkalinity of the ink to keep it within a suitable range, which helps the stability of the ink and the comfort during use. Hydroxypropyl-β-cyclodextrin: As the second coating material, hydroxypropyl-β-cyclodextrin can effectively encapsulate the modified dye in the cavity structure, reducing the direct contact between the dye and the skin and textiles. The preservative is used to prevent the ink from being contaminated by microorganisms during storage and use, ensuring the safety and shelf life of the product. Deionized water: As a solvent and diluent, deionized water ensures the uniformity and fluidity of the ink. These components, through their respective functions and their synergistic effects, jointly improve the performance of the washable watercolor pen ink. The coating effects of the modified dye and hydroxypropyl-β-cyclodextrin reduce the direct contact between the dye and the skin and textiles; the aqueous polyacrylic resin emulsion and the composite dispersant further disperse and encapsulate the dye, enhancing the washability of the ink; the humectant and pH regulator ensure the stability and comfort of the ink; the preservative ensures the safety of the product. The synergistic effects of these components enable the ink to have good washability while maintaining bright colors, and are particularly suitable for use by infants and school-age children.

[0007] Preferably, the modified dye, by mass parts, comprises the following raw materials for preparation: 8-10 parts of dye, 1-1.5 parts of emulsifier, 25-28 parts of polyacrylic resin, 4-5 parts of xanthan gum, 70-75 parts of butyl acetate, and 20-23 parts of deionized water.

[0008] Preferably, the preparation method of the modified dye comprises the following steps: S51. According to the mass parts, dissolve the dye in deionized water, add the emulsifier, and perform ultrasonic dispersion treatment for 30-40 minutes to obtain a uniform and stable aqueous phase; dissolve the polyacrylic resin in butyl acetate, then add xanthan gum, and perform ultrasonic treatment for 50-60 minutes to obtain a uniformly dispersed oil phase; S52. According to the mass parts, slowly drop the aqueous phase into the oil phase. During the dropping, use a high-speed shear mixing emulsifier to homogenize at a speed of 2500-3000 r / min, so that the droplets are wrapped by the polyacrylic resin in the oil phase to initially form a microcapsule structure; S53. After complete emulsification, continue to stir at 400 r / min for 15-20 minutes to allow the organic solvent to fully volatilize, and then place it in a vacuum drying oven to dry at 70°C for 8-12 hours to remove the moisture on the surface of the microcapsules and the residual organic solvent, thus obtaining the modified dye.

[0009] By adopting the above technical solution, the prepared modified dye forms a microcapsule structure by wrapping the dye with polyacrylic resin to achieve the first coating, which can largely avoid the combination of the dye and the skin, and has good re-solubility on the skin, does not affect the color degree of the original color of the dye, and fully improves the washability of the dye.

[0010] Preferably, the dye is composed of Acid Red 18#, Acid Yellow 23#, and Acid Blue 9# in a mass parts ratio of 3:5:2-4.

[0011] Preferably, the emulsifier is composed of sodium dodecyl benzene sulfonate and sodium fatty alcohol polyoxyethylene ether sulfate in a mass parts ratio of 3:4.

[0012] Preferably, the preparation method of the aqueous polyacrylic resin emulsion comprises the following steps: S61. Preparation of pre-emulsion: According to the mass parts, sequentially add 75 parts of deionized water, 0.75 parts of sodium dodecyl sulfate, 1 part of sodium fatty alcohol polyoxyethylene ether sulfate, and 0.15 parts of sodium bicarbonate into a reactor, and stir until completely dissolved to form an emulsifier aqueous solution; S62. Pre-mixing of monomers: According to the mass parts, mix 30 parts of methyl methacrylate, 20 parts of butyl acrylate, 3 parts of acrylic acid, 1 part of hydroxypropyl acrylate, and 1 part of glycidyl methacrylate evenly to obtain a mixed monomer liquid; S63. Preparation of initiator solution: Dissolve 0.5 part of ammonium persulfate in 10 parts of deionized water to prepare an initiator solution with a mass concentration of 5%. S64. Polymerization reaction: Place the aqueous emulsifier solution in a reactor, heat it to 82 °C, first add 20% of the mixed monomer solution and 20% of the initiator solution to initiate the prepolymerization reaction, then heat it to 82 °C, and uniformly add the remaining 80% of the mixed monomer solution and the remaining 80% of the initiator solution within 2 hours. After the addition is complete, react at 82 °C for 3 - 4 hours; then cool it to below 45 °C, slowly add ammonia water to adjust the pH to 7.8 - 8.2, and filter to obtain an aqueous polyacrylic resin emulsion.

[0013] By adopting the above technical solution, using methyl methacrylate (MMA) and butyl acrylate (BA) as the main reaction monomers, acrylic acid (AA), hydroxypropyl acrylate (HPA), and glycidyl methacrylate (GMA) as functional monomers, and using sodium dodecyl sulfate and sodium lauryl polyoxyethylene ether sulfate as the compound emulsifying and dispersing agent, an aqueous acrylic resin emulsion with good dispersibility and film-forming properties is synthesized. This aqueous acrylic resin emulsion has good compatibility with the modified dye, can well disperse and coat the modified dye, further reduces the contact between dye molecules and the skin and textiles, and can significantly improve the washability of watercolor pen ink.

[0014] Preferably, the composite dispersant is composed of sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in a mass ratio of 2:3.

[0015] By adopting the above technical solution, firstly, the main function of the composite dispersant is to promote the re - encapsulation of the dye molecules in the second coating by the aqueous polyacrylic resin emulsion. This re - encapsulation process can further reduce the contact between dye molecules and the skin and textiles, thus significantly improving the washability of watercolor pen ink. Secondly, there may be a synergistic effect between sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in the composite dispersant. This synergistic effect may be reflected in the following aspects: Emulsification and dispersion: Both sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 are surfactants, which can reduce the surface tension of water, thus promoting the dispersion and uniform distribution of dyes in water. At the same time, they may also contribute to the formation and stability of the emulsion. Fatty alcohol polyoxyethylene ether AEO-3 has good wetting and permeability, which can help dyes better penetrate into paper or other substrates. In summary, sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in the composite dispersant work together through their emulsification and dispersion, wetting and penetration and other effects, jointly improving the washability and other properties of watercolor pen ink.

[0016] Preferably, the humectant is one of glycerol and polyethylene glycol.

[0017] Preferably, the preservative is calcium sorbate; the pH regulator is ethanolamine.

[0018] In a second aspect, the present application provides a method for preparing washable watercolor pen ink, adopting the following technical solution: As a general technical concept, the present application also provides the method for preparing the above-mentioned washable watercolor pen ink, including the following steps: S101. According to parts by mass, add deionized water and a composite dispersant into a glass beaker, stir and dissolve, then add hydroxypropyl-β-cyclodextrin, stir evenly, add a modified dye, and continue to stir for 10-15 minutes to obtain a mixed solution A; S102. According to parts by mass, add an aqueous polyacrylic resin emulsion, a humectant, a pH regulator, and a preservative into the mixed solution A and stir evenly to obtain washable watercolor pen ink.

[0019] In summary, the beneficial technical effects of the present application are as follows: 1. Multiple coating structure: Through the multiple coating structure of hydroxypropyl-β-cyclodextrin and polyacrylic resin, the stability of the modified dye in the watercolor pen ink is significantly improved. This structure can effectively prevent the direct contact of the dye with the skin or textile, thereby reducing the staining problem.

[0020] 2. Improved washability: After the modified dye is encapsulated by the polyacrylic resin to form a microcapsule structure, its binding ability to the skin is reduced, and at the same time, it has good redissolvability on the skin and does not affect the color degree of the original color of the dye. In addition, the use of the composite dispersant further reduces the contact between the dye molecules and the skin and textile, significantly improving the washability of the watercolor pen ink.

[0021] 3. Safety: The raw materials used in the present application, such as hydroxypropyl-β-cyclodextrin and preservatives, all meet the safety standards, ensuring that the product is harmless to the human body during use. At the same time, the good washability makes the product more suitable for use by infants and school-age children, reducing skin irritation or discomfort caused by staining.

[0022] 4. Environmental protection: Using an aqueous polyacrylic resin emulsion as one of the main raw materials not only reduces the impact on the environment but also reduces the irritation to the skin. At the same time, the product is easy to clean, reducing water resource consumption during the washing process. Specific embodiments

[0023] The following will describe the implementation scheme of the present application in detail in combination with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are adopted. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0024] In the following Examples and Preparation Examples, 1 part means 100 g.

[0025] Preparation Example 1 Preparation of Modified Dye The modified dye, by mass parts, comprises the following preparation raw materials: 9 parts of dye, 1.3 parts of emulsifier, 27 parts of polyacrylic resin, 4.5 parts of xanthan gum, 73 parts of butyl acetate, and 22 parts of deionized water. The dye is composed of Acid Red 18#, Acid Yellow 23#, and Acid Blue 9# in a mass parts ratio of 3:5:3. The emulsifier is composed of sodium dodecylbenzenesulfonate and sodium fatty alcohol polyoxyethylene ether sulfate in a mass parts ratio of 3:4. The preparation method of the above-mentioned modified dye comprises the following steps: S51. According to the mass parts, dissolve the dye in deionized water, add the emulsifier, and perform ultrasonic dispersion treatment for 35 minutes to obtain a uniform and stable aqueous phase; dissolve the polyacrylic resin in butyl acetate, then add xanthan gum, and perform ultrasonic treatment for 55 minutes to obtain a uniformly dispersed oil phase. S52. According to the mass parts, slowly drop the aqueous phase into the oil phase. While dropping, use a high-speed shear mixing emulsifier to homogenize at a speed of 2800 r / min, so that the droplets are wrapped by the polyacrylic resin in the oil phase to initially form a microcapsule structure; S53. After complete emulsification, continue to stir at 400 r / min for 18 minutes to fully volatilize the organic solvent, and then place it in a vacuum drying oven and dry at 70°C for 10 hours to remove the moisture on the surface of the microcapsules and the residual organic solvent, thus obtaining the modified dye.

[0026] Preparation Example 2 Preparation of Aqueous Polyacrylic Resin Emulsion The preparation method of the aqueous polyacrylic resin emulsion comprises the following steps: S61. Preparation of pre-emulsion: According to the mass parts, sequentially add 75 parts of deionized water, 0.75 part of sodium dodecyl sulfate, 1 part of sodium fatty alcohol polyoxyethylene ether sulfate, and 0.15 part of sodium bicarbonate into a reactor, and stir until completely dissolved to form an emulsifier aqueous solution. S62. Pre-mixing of monomers: According to the mass parts, mix 30 parts of methyl methacrylate, 20 parts of butyl acrylate, 3 parts of acrylic acid, 1 part of hydroxypropyl acrylate, and 1 part of glycidyl methacrylate evenly to obtain a mixed monomer solution. S63. Preparation of initiator solution: Dissolve 0.5 part of ammonium persulfate in 10 parts of deionized water to prepare an initiator solution with a mass concentration of 5%. S64. Polymerization reaction: Place the aqueous solution of emulsifier in a reactor, heat it up to 82 °C, first add 20% of the mixed monomer solution and 20% of the initiator solution to initiate the pre-polymerization reaction, then heat it up to 82 °C, and uniformly add the remaining 80% of the mixed monomer solution and the remaining 80% of the initiator solution within 2 hours. After the addition is complete, react at 82 °C for 4 hours; then cool it down to below 45 °C, slowly add ammonia water to adjust the pH to 8, and filter to obtain the aqueous polyacrylic resin emulsion.

[0027] Example 1 A washable watercolor pen ink, by mass, includes the following preparation raw materials: 3 parts of modified dye, 8 parts of aqueous polyacrylic resin emulsion, 2 parts of composite dispersant, 22 parts of glycerol, 0.2 parts of ethanolamine, 5 parts of hydroxypropyl-β-cyclodextrin, 0.2 parts of calcium sorbate, and 55 parts of deionized water. The composite dispersant is composed of sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in a mass ratio of 2:3. The preparation method of the above washable watercolor pen ink includes the following steps: S101. According to the mass parts, add deionized water and the composite dispersant to a glass beaker, stir and dissolve, then add hydroxypropyl-β-cyclodextrin, stir evenly, add the modified dye, and continue to stir for 10 minutes to obtain the mixed solution A. S102. According to the mass parts, add the aqueous polyacrylic resin emulsion, glycerol, ethanolamine, and calcium sorbate to the mixed solution A and stir evenly to obtain the washable watercolor pen ink.

[0028] Example 2 A washable watercolor pen ink, by mass, includes the following preparation raw materials: 5 parts of modified dye, 10 parts of aqueous polyacrylic resin emulsion, 2.5 parts of composite dispersant, 25 parts of polyethylene glycol, 0.5 parts of ethanolamine, 7 parts of hydroxypropyl-β-cyclodextrin, 0.3 parts of calcium sorbate, and 60 parts of deionized water. The composite dispersant is composed of sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in a mass ratio of 2:3. The preparation method of the above washable watercolor pen ink includes the following steps: S101. According to the mass parts, add deionized water and the composite dispersant to a glass beaker, stir and dissolve, then add hydroxypropyl-β-cyclodextrin, stir evenly, add the modified dye, and continue to stir for 15 minutes to obtain the mixed solution A. S102. According to the mass parts, add the aqueous polyacrylic resin emulsion, polyethylene glycol, ethanolamine, and calcium sorbate to the mixed solution A and stir evenly to obtain the washable watercolor pen ink.

[0029] Example 3 A washable watercolor pen ink comprises the following raw materials, measured by weight: 4 parts of modified dye, 9 parts of water-based polyacrylic resin emulsion, 2.3 parts of composite dispersant, 23 parts of glycerol, 0.3 parts of ethanolamine, 6 parts of hydroxypropyl-β-cyclodextrin, 0.25 parts of calcium sorbate, and 57 parts of deionized water, wherein the composite dispersant is composed of sodium dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether AEO-3 in a weight ratio of 2:3; The method for preparing the washable watercolor pen ink comprises the following steps: S101. Add deionized water and a composite dispersant into a glass beaker according to their weight fractions, stir to dissolve, add hydroxypropyl-β-cyclodextrin, stir evenly, add a modified dye, and continue stirring for 13 minutes to obtain a mixed solution A. S102. Add water-based polyacrylic acid resin emulsion, glycerol, ethanolamine and calcium sorbate into mixed solution A according to their weight proportions and stir evenly to obtain washable watercolor pen ink.

[0030] Comparative Example 1 The same as Example 3, except that an equal amount of polyvinyl pyrrolidone K30 is used to replace the aqueous polyacrylic acid resin emulsion.

[0031] Comparative Example 2 The same as Example 3, except that a mixed dye (composed of acid red 18#, acid yellow 23# and acid blue 9# in a mass ratio of 3:5:3) of equal mass parts is used instead of the modified dye.

[0032] Comparative Example 3 The same as Example 3, except that 0 part of hydroxypropyl-β-cyclodextrin is used.

[0033] Comparative Example 4 The same as Example 3, except that the composite dispersant is sodium dodecylbenzene sulfonate.

[0034] Comparative Example 5 The same as Example 3, except that the composite dispersant is fatty alcohol polyoxyethylene ether AEO-3.

[0035] Performance Testing The washable watercolor pen inks prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were sampled and made into pens respectively. The pen components include a water storage core, a fiber pen tip, and a plastic casing, etc. The amount of ink added to each pen is 1.5 grams, and the corresponding watercolor pens are marked as Examples 1 to 3 and Comparative Examples 1 to 5. The following tests were performed, and each group of test samples was tested 3 times, and the results were averaged; the test results are shown in Table 1.

[0036] 1. Skin washability test method: Step 1: Wash the tester's hand with soap and warm running tap water, and dry it thoroughly with a paper towel. Step 2: Draw the colors on the back of the hand and the palm five times repeatedly with the watercolor pens of Examples 1 - 3 and Comparative Examples 1 - 5 respectively, and dry for 5 minutes at room temperature of 25°C. Step 3: After drying for 15 minutes, rinse with running tap water for 2 minutes, dry the hand with a paper towel, and then grade it according to the following grading criteria. Grading criteria for skin staining after washing: 0 = no visible staining, 1 = slight staining, 2 = medium staining, 3 = severe staining, 4 = seems not to have been washed.

[0037] 2. Textile washability test method: Draw six lines with a length of about 20 cm on 8 standard fiber test cloths (a standard cloth specially used for color fastness detection, and the fabric is woven from six materials: pure acetate fiber, pure cotton, pure polyamide, pure acrylic, pure polyester, and pure wool)) with the watercolor pens of Examples 1 - 3 and Comparative Examples 1 - 5 respectively. After 24 hours, put the marked standard fiber test cloths into a drum washing machine, select the standard mode to wash for 50 minutes, dry the standard fiber test cloths after one machine wash, and grade them according to the following grading criteria. Grading criteria for test cloth staining after washing: 0 = no visible staining, 1 = slight staining, 2 = medium staining, 3 = severe staining, 4 = seems not to have been washed.

[0038] Table 1 Washability test Project Washability of skin Washability of fabric Example 1 0 0 Example 2 0 0 Example 3 0 0 Comparative Example 1 2 2 Comparative Example 2 2 2 Comparative Example 3 1 1 Comparative Example 4 1 1 Comparative Example 5 1 1 Analyzing the data in Table 1, it can be seen that: 1) The washable watercolor pen inks prepared in Examples 1 - 3 can be washed off with water whether painted on the skin or textile.

[0039] 2) Combining the performance comparison and analysis of the washable watercolor pen inks prepared in Example 3 and Comparative Example 1 shows that in this application, methyl methacrylate (MMA) and butyl acrylate (BA) are used as the main reaction monomers, acrylic acid (AA), hydroxypropyl acrylate (HPA), and glycidyl methacrylate (GMA) are functional monomers, and sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate are used as the compound emulsifying and dispersing agents to synthesize an aqueous acrylic resin emulsion with good dispersibility and film-forming properties. This aqueous acrylic resin emulsion has good compatibility with the modified dyes, can well disperse and coat the modified dyes, further reduces the contact between dye molecules and the skin and textile, and can significantly improve the washability of the watercolor pen ink.

[0040] 3) Comparative analysis of the performance of the washable watercolor pen ink prepared by combining Example 3 and Comparative Example 2 shows that the modified dye prepared in this application forms a microcapsule structure by encapsulating the dye with polyacrylic resin to achieve the first coating, which can largely avoid the combination of the dye and the skin, and has good re-solubility on the skin without affecting the color degree of the original color of the dye, thus fully improving the washability of the dye.

[0041] 4) Comparative analysis of the performance of the washable watercolor pen ink prepared by combining Example 3 and Comparative Example 3 shows that adding hydroxypropyl-β-cyclodextrin in this application enables the modified dye molecules to enter the cavity of cyclodextrin in hydroxypropyl-β-cyclodextrin for the second coating by utilizing the cavity structure of cyclodextrin, thereby reducing the contact with the skin and textiles and improving the washability of the watercolor pen ink.

[0042] 5) Comparative analysis of the performance of the washable watercolor pen ink prepared by combining Example 3 and Comparative Examples 4 - 5 shows that the composite dispersant is composed of sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in a mass ratio of 2:3. The main function of the composite dispersant is to promote the re-encapsulation of the second-coated dye molecules by the aqueous polyacrylic resin emulsion. This re-encapsulation process can further reduce the contact between the dye molecules and the skin and textiles, thereby significantly improving the washability of the watercolor pen ink. Secondly, there may be a synergistic effect between sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in the composite dispersant. This synergistic effect may be reflected in the following aspects: Emulsification and dispersion: Both sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 are surfactants, which can reduce the surface tension of water, thus promoting the dispersion and uniform distribution of the dye in water. At the same time, they may also contribute to the formation and stability of the emulsion. Fatty alcohol polyoxyethylene ether AEO-3 has good wettability and permeability, which can help the dye better penetrate into the paper or other substrates. In summary, sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether AEO-3 in the composite dispersant work together through their emulsification and dispersion, wetting and penetration and other effects to jointly improve the washability of the watercolor pen ink.

[0043] The above embodiments are only used to explain and illustrate the technical solutions of this application rather than limit them. Although the above embodiments have specifically described this application, those skilled in the art should understand that they can still modify the specific implementation manners of the present invention or make equivalent replacements. Any modification and equivalent replacement without departing from the spirit and scope of this application should be covered by the protection scope of this application.

Claims

1. A washable watercolor pen ink, characterized in that: The preparation raw materials include the following by weight: 3-5 parts of modified dye, 8-10 parts of water-based polyacrylic resin emulsion, 2-2.5 parts of composite dispersant, 22-25 parts of moisturizing agent, 0.2-0.5 parts of pH adjuster, 5-7 parts of hydroxypropyl-β-cyclodextrin, 0.2-0.3 parts of preservative and 55-60 parts of deionized water.

2. A washable watercolor pen ink according to claim 1, characterized in that: The modified dye comprises the following raw materials by weight: 8-10 parts of dye, 1-1.5 parts of emulsifier, 25-28 parts of polyacrylic acid resin, 4-5 parts of xanthan gum, 70-75 parts of butyl acetate and 20-23 parts of deionized water.

3. A washable watercolor pen ink according to claim 2, characterized in that: The dye is composed of acid red 18#, acid yellow 23# and acid blue 9# in a mass ratio of 3:5:2-4.

4. The washable watercolor pen ink according to claim 2, characterized in that: The emulsifier is composed of sodium dodecylbenzene sulfonate and sodium fatty alcohol polyoxyethylene ether sulfate in a mass ratio of 3:

4.

5. The washable watercolor pen ink according to claim 2, characterized in that: The preparation method of the modified dye comprises the following steps: S51. Dissolve the dye in deionized water according to the mass fraction, add an emulsifier, and perform ultrasonic dispersion treatment for 30-40 minutes to obtain a uniform and stable aqueous phase; dissolve the polyacrylic acid resin in butyl acetate, add xanthan gum, and perform ultrasonic dispersion treatment for 50-60 minutes to obtain a uniformly dispersed oil phase; S52, slowly dropping the water phase into the oil phase according to the mass fraction, and while dropping, homogenizing at a high speed of 2500-3000 r / min using a high-speed shear mixer emulsifier, so that the droplets are wrapped by the polyacrylic acid resin in the oil phase, and a microcapsule structure is initially formed; S53. After complete emulsification, continue stirring at 400 r / min for 15-20 minutes to allow the organic solvent to fully evaporate, then place in a vacuum drying oven at 70° C. for 8-12 hours to remove moisture and residual organic solvent on the surface of the microcapsule to obtain a modified dye.

6. The washable watercolor pen ink according to claim 1, characterized in that: The preparation method of the aqueous polyacrylic acid resin emulsion comprises the following steps: S61, pre-emulsion preparation: according to the mass parts, 75 parts of deionized water, 0.75 parts of sodium lauryl sulfate, 1 part of fatty alcohol polyoxyethylene ether sodium sulfate and 0.15 parts of sodium bicarbonate were added to the reactor in sequence, and stirred until completely dissolved to form an emulsifier aqueous solution; S62, monomer premixing: according to the mass parts, 30 parts of methyl methacrylate, 20 parts of butyl acrylate, 3 parts of acrylic acid, 1 part of hydroxypropyl acrylate and 1 part of glycidyl methacrylate are mixed uniformly to obtain a mixed monomer liquid; S63, preparation of initiator solution: dissolve 0.5 parts of ammonium persulfate in 10 parts of deionized water to prepare an initiator solution with a mass concentration of 5%; S64. Polymerization reaction: Place the emulsifier aqueous solution in a reactor, heat it to 82°C, first add 20% mixed monomer liquid and 20% initiator solution to initiate a prepolymerization reaction, then heat it to 82°C, and uniformly add the remaining 80% mixed monomer liquid and the remaining 80% initiator solution dropwise within 2 hours. After the addition is complete, react at 82°C for 3-4 hours; then cool it to below 45°C, slowly add ammonia water to adjust the pH to 7.8-8.2, filter, and obtain an aqueous polyacrylic resin emulsion.

7. The washable watercolor pen ink according to claim 1, characterized in that: The composite dispersant is composed of sodium dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether AEO-3 in a mass ratio of 2:

3.

8. The washable watercolor pen ink according to claim 1, characterized in that: The moisturizing agent is one of glycerol and polyethylene glycol.

9. The washable watercolor pen ink according to claim 1, characterized in that: The preservative is calcium sorbate; and the pH adjuster is ethanolamine.

10. A method for preparing the washable watercolor pen ink according to any one of claims 1 to 9, characterized in that: The following steps are involved: S101. Add deionized water and a composite dispersant into a glass beaker according to their weight fractions, stir to dissolve, add hydroxypropyl-β-cyclodextrin, stir evenly, add a modified dye, and continue stirring for 10-15 minutes to obtain a mixed solution A. S102, adding water-based polyacrylic acid resin emulsion, moisturizer, pH adjuster and preservative into mixed solution A according to their weight proportions and stirring evenly to obtain washable watercolor pen ink.