A 15-day cap-off water-based marker ink and a method for preparing the same

Abstract

A 15-day cap-off non-drying water-based marker ink and a preparation method thereof, comprising the following mass components: a water-based polyurethane dispersion: 20-30 parts, a humectant: 10-15 parts, potassium sorbate: 0.2-0.5 parts, a surfactant: 0.5-0.8 parts, a dye: 1-3 parts, deionized water: 30-50 parts; wherein: the water-based polyurethane dispersion is an aliphatic polyurethane dispersion, the film forming temperature is 5-10 DEG C, and the glass transition temperature (Tg) is lower than -20 DEG C.

Description

Technical Field

[0001] This invention relates to water-based marker ink, specifically to a water-based marker ink that does not dry after 15 days of cap removal and its preparation method. Background Technology

[0002] Water-based markers have become mainstream products in the fields of art drawing, student stationery, and office marking due to their advantages of mild odor, environmental friendliness, non-toxicity, washability, and compatibility with various substrates such as paper, journaling, and hand-drawing. However, existing water-based markers on the market have a core defect: they dry out and clog easily when the cap is removed. Within a few hours to a day or two after opening and removing the cap, the water in the ink at the tip evaporates rapidly, and the dye and resin precipitate out, dry, and clog the fiber tip. When used again, the ink stops, skips, or even stops flowing altogether. Users must keep the cap tightly closed at all times, resulting in a poor user experience in scenarios where the cap is frequently opened and closed.

[0003] To improve the drying problem, most existing technologies use a single high-boiling-point moisturizing solvent to enhance water-locking ability, but this has obvious shortcomings: 1. Excessive addition of humectant will significantly reduce the film-forming speed of the resin in the ink, resulting in slow drying of ink after writing, ink bleeding and blurring of paper, and blurred lines in drawings. 2. Simply adjusting the resin emulsion cannot simultaneously ensure film-forming strength and resistance to drying; clumping will still occur at the pen tip after the cap is removed for an extended period. 3. Ordinary preservative systems are prone to failure in long-term open volatilization and contact with airborne mold spores, making the ink susceptible to mold and deterioration during storage; 4. Poor dye compatibility, uneven mixing with humectants and surfactants, resulting in pigment precipitation and color paste separation.

[0004] Currently, the industry lacks a water-based marker ink formula that can prevent the nib from drying out and clogging even after being left open for 15 days without the cap removed, while also ensuring good color rendering, quick-drying ink, storage stability, and being environmentally friendly and non-toxic. This invention addresses these industry pain points by optimizing the overall formula system. Summary of the Invention

[0005] To address the technical problems of existing water-based markers in the background art, such as easy drying and clogging after the cap is removed, easy ink smudging, easy mold growth during storage, and pigment separation and sedimentation, this invention provides an environmentally friendly water-based marker ink that does not dry after the cap is removed for 15 days. It can still write normally and smoothly after being left open for a long time, while meeting the comprehensive performance requirements of food-grade contact safety, quick-drying ink, uniform coloring, and no mold growth or separation during long-term storage.

[0006] A water-based marker ink that does not dry after 15 days of cap removal comprises the following components by weight: water-based polyurethane dispersion: 20-30 parts, humectant: 10-15 parts, potassium sorbate: 0.2-0.5 parts, surfactant: 0.5-0.8 parts, dye: 1-3 parts, and deionized water: 30-50 parts. Among them, the waterborne polyurethane dispersion is an aliphatic polyurethane dispersion with a film-forming temperature of 5-10℃ and a glass transition temperature (Tg) below -20℃.

[0007] The moisturizer is one or more selected from glycerin, propylene glycol, and polyethylene glycol 400, or a mixture thereof.

[0008] The dyes are water-soluble synthetic or natural pigments.

[0009] Detailed Explanation of the Functions of Each Component 1. The water-based polyurethane dispersion is the base component of this invention, which has a low evaporation rate and a high molecular cross-linking water-locking structure: on the one hand, it quickly forms a dense waterproof ink film on the paper surface after writing to prevent ink from smudging and penetrating; on the other hand, it encapsulates water molecules in the ink, greatly reducing the rate of water evaporation when the pen tip is open, achieving long-lasting anti-drying from the substrate level, and is the core raw material for achieving 15 days of no drying after removing the cap.

[0010] 2. The humectant, combined with the resin emulsion, forms a dual water-locking mechanism, slowly releasing moisture and inhibiting ink drying and crystallization within the pen tip's capillary fibers. The addition range is limited to 10-15 parts, ensuring 15 days of open-air humectant retention without causing excessive ink drying or ink bleeding on the paper due to excessive humectant. A preferred polyol-based humectant blend (propylene glycol, glycerin, and diethylene glycol monomethyl ether) is used, with a gradient evaporation rate to achieve short-term and long-term layered water-locking.

[0011] 3. Potassium sorbate is a broad-spectrum antibacterial and preservative agent, suitable for water-based systems. It inhibits the growth of mold and bacteria during open storage and long-term storage, preventing ink from becoming moldy and smelly, and preventing flocculent matter from clogging the pen tip. The addition amount is controlled at 0.2~0.5 parts, which meets the food-grade safety limits for stationery that comes into contact with skin or is accidentally ingested, and has no irritating odor.

[0012] 4. Surfactants improve the overall wetting and flowability of the ink, reduce the surface tension of the ink, and allow the ink to evenly wet the nib fibers; at the same time, they disperse dye particles, prevent pigment agglomeration and sedimentation, ensure even ink flow without interruption during writing, and help improve the resolubility of dried residue after the cap is removed.

[0013] 5. Food-grade dyes are water-soluble and have high color saturation and stable water solubility. They do not leach heavy metals or toxic solvents, making them safer for children. The recommended addition amount is 1-3 parts to balance the coloring depth and ink flow, preventing excessive dye precipitation and clumping.

[0014] 6. Deionized water is used as a solvent carrier to dissolve and disperse all solid and liquid phase components, regulate the overall viscosity of the ink, and adapt to the capillary flow structure of the marker pen tip.

[0015] Ink preparation method 1. Material preparation: Weigh each raw material according to its mass percentage; 2. Pre-dissolution and dispersion: Add all deionized water to the stirred tank, and add food-grade dye and surfactant in sequence while stirring at low speed. Stir for 15-25 minutes until the dye is completely dissolved and there are no particles. 3. Add functional additives: Add humectant and potassium sorbate to the system, stir at room temperature for 10 minutes to make the preservative, humectant and aqueous solution completely miscible; 4. Base material emulsification: Slowly add water-based polyurethane dispersion and stir at medium speed for 30-40 minutes to complete the homogeneous compounding of emulsion and aqueous solution, avoiding resin demulsification and stratification; 5. Homogenization and defoaming: Homogenize and stir at high speed for 10-15 minutes to remove air bubbles from the system, filter to remove trace impurity particles, and obtain the finished marker ink; 6. Filling: Fill the filtered ink into the marker pen barrel and assemble the fiber nib and cap.

[0016] Key performance indicators of products 1. Cap removal and wind-drying resistance: At room temperature of 25℃ and humidity of 50~60%, the pen tip can be completely capped and left open for 15 days. After capping and soaking for 10 seconds, it can write smoothly without ink breaks, skipping, or hard lumps clogging the tip. 2. Writing performance: The ink dries on 80g drawing and writing paper in 30-60 seconds without obvious bleeding or smudging; 3. Storage stability: After 12 months of sealed storage at room temperature, there is no stratification, sedimentation, mold, or odor. 4. Safety attributes: All accessible components are made of food-grade / environmentally friendly water-based raw materials, free of benzene solvents, heavy metals, and formaldehyde, and can be washed and wiped clean. Attached Figure Description

[0017] Figure 1-3 This is a third-party test report for this product. Specific Implementation Example

[0018] 1. Material preparation: Weigh each raw material according to the following mass percentages; The mixture contains 25 parts of waterborne polyurethane dispersion, 12 parts of humectant, 0.35 parts of potassium sorbate, 0.65 parts of surfactant, 2 parts of food-grade dye, and 40 parts of deionized water.

[0019] 2. Pre-dissolution and dispersion: Add all deionized water to the stirred tank, and add food-grade dye and surfactant in sequence while stirring at low speed. Stir for 20 minutes until the dye is completely dissolved and there are no particles. 3. Add functional additives: Add humectant and potassium sorbate to the system, stir at room temperature for 10 minutes to make the preservative, humectant and aqueous solution completely miscible; 4. Base material emulsification: Slowly add water-based polyurethane dispersion and stir at medium speed for 35 minutes to complete the homogeneous compounding of emulsion and aqueous solution, avoiding resin demulsification and stratification; 5. Homogenization and defoaming: High-speed homogenization and stirring for 10 minutes to remove air bubbles in the system, and filtering to remove trace impurity particles to obtain the finished marker ink; 6. Filling: Fill the filtered ink into the marker pen barrel and assemble the fiber nib and cap. Example

[0020] 1. Material preparation: Weigh each raw material according to the following mass percentages; The mixture contains 20 parts of waterborne polyurethane dispersion, 10 parts of humectant, 0.2 parts of potassium sorbate, 0.5 parts of surfactant, 1 part of food-grade dye, and 48.3 parts of deionized water.

[0021] 2. Pre-dissolution and dispersion: Add all deionized water to the stirred tank, and add food-grade dye and surfactant in sequence while stirring at low speed. Stir for 15 minutes until the dye is completely dissolved and there are no particles. 3. Add functional additives: Add humectant and potassium sorbate to the system, stir at room temperature for 10 minutes to make the preservative, humectant and aqueous solution completely miscible; 4. Base material emulsification: Slowly add water-based polyurethane dispersion and stir at medium speed for 30 minutes to complete the homogeneous compounding of emulsion and aqueous solution, avoiding resin demulsification and stratification; 5. Homogenization and defoaming: High-speed homogenization and stirring for 10 minutes to remove air bubbles in the system, and filtering to remove trace impurity particles to obtain the finished marker ink; 6. Filling: Fill the filtered ink into the marker pen barrel and assemble the fiber nib and cap. Example

[0022] 1. Material preparation: Weigh each raw material according to the following mass percentages; The mixture contains 30 parts of waterborne polyurethane dispersion, 15 parts of humectant, 0.5 parts of potassium sorbate, 0.8 parts of surfactant, 3 parts of food-grade dye, and 50.7 parts of deionized water.

[0023] 2. Pre-dissolution and dispersion: Add all deionized water to the stirred tank, and add food-grade dye and surfactant in sequence while stirring at low speed. Stir for 25 minutes until the dye is completely dissolved and there are no particles. 3. Add functional additives: Add humectant and potassium sorbate to the system, stir at room temperature for 10 minutes to make the preservative, humectant and aqueous solution completely miscible; 4. Base material emulsification: Slowly add water-based polyurethane dispersion and stir at medium speed for 40 minutes to complete the homogeneous compounding of emulsion and aqueous solution, avoiding resin demulsification and stratification; 5. Homogenization and defoaming: High-speed homogenization and stirring for 15 minutes to remove air bubbles in the system, and filtering to remove trace impurity particles to obtain the finished marker ink; 6. Filling: Fill the filtered ink into the marker pen barrel and assemble the fiber nib and cap. Beneficial effects

[0024] 1. Long cap removal performance: Through the synergistic effect of a specific ratio of humectant and low Tg polyurethane, the ink loses water at the nib at an extremely slow rate, and can still write smoothly 15 days after the cap is removed.

[0025] 2. Safety: Potassium sorbate food preservative is used instead of traditional Kathon or BIT bactericides, and food-grade dyes are used instead of pigments, completely solving the problems of heavy metals and skin allergies.

[0026] 3. Storage stability: Potassium sorbate not only acts as a preservative in this weakly alkaline system (pH 6.9), but also serves as a buffer to prevent polyurethane from hydrolyzing during storage.

Claims

1. A water-based marker ink that does not dry after 15 days, characterized in that: The substance comprises the following components by weight: waterborne polyurethane dispersion: 20-30 parts, humectant: 10-15 parts, potassium sorbate: 0.2-0.5 parts, surfactant: 0.5-0.8 parts, dye: 1-3 parts, and deionized water: 30-50 parts.

2. The 15-day non-drying water-based marker ink according to claim 1, characterized in that: The waterborne polyurethane dispersion is an aliphatic polyurethane dispersion.

3. The 15-day non-drying water-based marker ink according to claim 2, characterized in that: The film-forming temperature of the aqueous polyurethane dispersion is 5-10℃.

4. The 15-day cap-free non-drying water-based marker ink according to claim 2, characterized in that: The glass transition temperature (Tg) of the aqueous polyurethane dispersion is below -20°C.

5. The 15-day cap-free non-drying water-based marker ink according to claim 1, characterized in that: The moisturizer is one or more selected from glycerin, propylene glycol, and polyethylene glycol 400, or a mixture thereof.

6. The 15-day non-drying water-based marker ink according to claim 1, characterized in that: The dyes are water-soluble synthetic or natural pigments.

7. A 15-day cap-removing, non-drying water-based marker ink according to any one of claims 1-5, the preparation method of which includes the following steps: Preparation of materials: Weigh each raw material according to its mass percentage; Pre-dissolution and dispersion: Add all deionized water to the stirred tank, and add food-grade dye and surfactant in sequence while stirring at low speed. Stir for 15-25 minutes until the dye is completely dissolved and there are no particles. Add functional additives: Add humectant and potassium sorbate to the system, stir at room temperature for 10 minutes to make the preservative, humectant and aqueous solution completely miscible; Base material emulsification: Slowly add water-based polyurethane dispersion and stir at medium speed for 30-40 minutes to complete the homogeneous compounding of emulsion and aqueous solution, avoiding resin demulsification and stratification; Homogenization and defoaming: High-speed homogenization and stirring for 10-15 minutes to remove air bubbles in the system, filter to remove trace impurity particles, and obtain the finished marker ink; Filling: Fill the filtered ink into the marker pen barrel and assemble the fiber nib and cap.

Images