Water-based ink for whiteboard pen

Abstract

The water-based ink for the whiteboard marker is prepared by taking water as a solvent, graphene oxide as a coloring agent and flaky inorganic mineral substances as functional filler through a micro-jet high-pressure homogenization process, and has the characteristics of short stitch drying time and excellent erasability.

Description

Technical Field

[0001] The invention relates to water-based ink for a whiteboard pen. Background Art

[0002] Whiteboard markers are a common writing tool used in daily office and classroom settings. They can be used to write on whiteboards or colored boards made of non-absorbent surfaces such as plastic, enamel, and lacquer. They can be easily erased after a certain period of time, allowing for repeated use. Currently, the ink used in commercially available whiteboard markers has a pungent odor, which comes from the solvent in the ink.

[0003] Currently, the solvent commonly used in whiteboard pen ink is ethanol, or a mixture of ethanol and water (the content of ethanol in the mixture is much higher than that of water). This is because the traces need to dry quickly. The product standard QB / T 2859-2007 "Markers for Whiteboards" requires the traces to dry in ≤30s.

[0004] Patent ZL201210258138.2, "An Erasable Whiteboard Ink and Its Manufacturing Method," describes the whiteboard ink's solvent as a combination of water, C2-C4 lower alcohols, and C2-C8 ethers. Patent ZL202011091635.9, "A Whiteboard Pen Ink, Its Preparation Method, and Whiteboard Pen," describes the whiteboard pen's ink's solvent as at least one of ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, and butyl acetate. Patent ZL201611011430.9, "An Erasable Water-Based Whiteboard Pen Ink and Its Preparation Method," describes the whiteboard pen's ink's solvent as deionized water, but uses surfactants, humectants, lubricants, and ethanol as additives. Patent 201910606662.6 (application number), "A Method for Preparing Water-Based Whiteboard Pen Ink," describes the whiteboard pen's ink's solvents as water and ethanol. It can be seen that most of the currently disclosed whiteboard pen ink formulas still need to use organic solvents to meet the drying requirements, which makes the whiteboard pen ink have a pungent odor and brings a bad experience to consumers. The scientific research article "The Effect of Additives on the Performance of Water-based Whiteboard Pen Ink" published in the 168th issue of "China Pen Making" in 2023 discussed the improvement of the drying properties of water-based inks by adding glacial acetic acid, hydrogen peroxide and nano-calcium carbonate to whiteboard pen inks. The study found that: when hydrogen peroxide is used as an additive, the effect is best, and the quick-drying property and the time left on the board are improved; the second is the use of nano-calcium carbonate as an additive, and the effect is higher than the effect of the whiteboard pen before improvement. As an unstable chemical substance, hydrogen peroxide will automatically decompose into water and oxygen over time when added to the ink. Obviously, it is difficult to ensure long-term effectiveness. The addition of nano-calcium carbonate has limited effect on improving drying properties and will significantly increase the viscosity of the ink.

[0005] In addition, the problem that the lines written by whiteboard pens leave traces after being wiped off after a period of time also brings great inconvenience to consumers. The product standard QB / T 2859-2007 "Whiteboard Marker" defines the performance involved in this point as time-erasability, requiring that there should be no traces on the board surface after the lines are left for 30 days. However, the actual use of whiteboard pens is not ideal. Patent ZL202011091635.9 "A whiteboard pen ink, its preparation method and whiteboard pen" uses a cross-linked acrylic resin modified with a silane coupling agent as a film-forming resin to make the ink lines cover the whiteboard in strips. The ink can be torn off in strips and the board will not be dirty after being wiped off after 3 months. Patent 201911024419.X (application number) “An easy-to-clean whiteboard pen ink and its preparation method” uses a block polymer containing a lipophilic segment methacrylate-3-trimethylsilyl propyl ester and a hydrophilic segment N-isopropyl acrylamide as a dispersant. The lipophilic segment of the block polymer encapsulates the lipophilic dye or insoluble pigment, while the hydrophilic segment of the block polymer stretches in the solvent system to form a stable core (dye or pigment)-shell (polymer) structure, encapsulating the dye or pigment in the polymer. When writing, the solvent evaporates and the shell forms a continuous polymer film. When erasing, the entire film together with the encapsulated pigment can be easily peeled off from the whiteboard, thereby achieving easy cleaning and easy erasing of the whiteboard pen ink. The cross-linked acrylic resin modified with a silane coupling agent or the block polymer containing the lipophilic segment methacrylate-3-trimethylsilyl propyl ester and the hydrophilic segment N-isopropyl acrylamide has a complex structure and needs to be customized, which brings obstacles to the industrial production of such technical solutions. In general, there are still challenges in improving the erasability of whiteboard pen ink over time. Summary of the Invention

[0006] The present invention aims to overcome the deficiencies of the prior art and provide an easy-to-dry-erase water-based ink for a whiteboard marker and a preparation method thereof.

[0007] The object of the present invention is achieved through the following solutions:

[0008] The invention discloses a water-based ink for a whiteboard pen. The water-based ink comprises, by weight, 5.0 to 8.0 parts of graphene oxide, 5.0 to 8.0 parts of functional fillers, 2.0 to 3.2 parts of dispersing aids, 3.0 to 4.8 parts of film-forming resins, 0.5 to 1.0 parts of surfactants, 0.1 to 0.5 parts of bactericides, 0.5 to 0.8 parts of pH regulators, and 73.0 to 84.0 parts of deionized water.

[0009] The functional filler is one of montmorillonite, talc and heavy calcium carbonate.

[0010] The dispersing aid is styrene maleic anhydride copolymer.

[0011] The film-forming resin is PVA resin.

[0012] The surfactant is an acetylene glycol surfactant.

[0013] The pH regulator is an organic alkaline substance.

[0014] The bactericide is one of isothiazolinone substances or benzisothiazolinone substances.

[0015] Whiteboard pen of the present invention adopts the following method to make with marking ink:

[0016] Step 1. Add deionized water, graphene oxide, functional filler, dispersing aid and pH adjuster to a container with a stirring device according to the formula measurement requirements. After stirring evenly, transfer the mixed solution into a microjet high-pressure homogenizer and homogenize it 3 to 5 times at 1500 to 1800 atmospheres to obtain a stable aqueous dispersion of graphene oxide and functional filler.

[0017] Step 2. Add the PVA resin to the aqueous dispersion prepared in step 1, stir for 2-3 hours, then add the surfactant and fungicide, continue stirring for 0.5 hours, and then end the stirring. Filter the ink prepared above through a 1000 mesh filter bag to obtain a filtrate, which is the water-based ink for whiteboard markers.

[0018] The present invention uses graphene oxide as a colorant. Graphene oxide is a black graphene flake with a large number of hydrophilic groups such as hydroxyl and carboxyl groups on its surface, thus having good water dispersibility.

[0019] The functional fillers montmorillonite, talc and heavy calcium carbonate used in the present invention are all inorganic minerals with a flaky structure.

[0020] Microfluidic high-pressure homogenization is a highly effective method for obtaining a uniform and stable dispersion system by pressurizing the material with a high-pressure pump, forcing the material through a microchannel with a special internal structure. When the material passes through the microchannel at high speed, the pressure in the fluid drops sharply, forming a supersonic flow rate. The cavitation effect, shear force, and impact force are used to achieve particle fragmentation and homogenization. The present invention uses a microfluidic high-pressure homogenization process to form a uniform and stable black aqueous dispersion of graphene oxide and functional fillers under the action of a dispersant. Compared with the traditional grinding process using zirconium beads as the grinding medium, the microfluidic high-pressure homogenization process is beneficial for maintaining the flaky structure of graphene oxide and functional fillers.

[0021] The density of montmorillonite powder is about 2g / cm 3 The density of talcum powder is 2.7~2.8g / cm 3 The density of heavy calcium carbonate is 2.6~2.9g / cm 3, both greater than the density of graphene oxide. When writing on a whiteboard, the functional filler in the water-based ink of the present invention tends to settle at the bottom due to its higher density, while the graphene oxide is primarily distributed in the upper layer, forming a black trace as the film-forming resin solidifies. Compared to granular forms, the flake-shaped graphene oxide and functional filler are easier to erase from the whiteboard. Because the graphene oxide is separated by the functional filler, the trace remains highly erasable even after prolonged exposure.

[0022] The interaction area and interaction force between the flakes are greater than those between the particles. As the functional fillers with flake structures and graphene oxide are deposited on the whiteboard, the moisture in the ink is quickly discharged to the surface, which is conducive to the rapid drying of the traces.

[0023] The present invention uses styrene-maleic anhydride copolymer as a dispersant. The π-electron cloud of the benzene ring in the styrene-maleic anhydride copolymer forms a π-π conjugated interaction with the π-electron cloud on the graphene oxide sheet, which can stably disperse the graphene oxide. Simultaneously, the maleic anhydride in the copolymer hydrolyzes under the action of a pH regulator to generate carboxylate ions, which have an affinity for polar inorganic minerals. This ensures the stable dispersion of both graphene oxide and inorganic minerals.

[0024] Compared with the prior art, the whiteboard pen of the present invention has the following advantages using water-based ink:

[0025] 1. Deionized water is used as the solvent, and the ink is environmentally friendly and has no irritating odor.

[0026] 2. Using graphene oxide as a colorant and flaky inorganic minerals as functional fillers, a water-based ink is prepared through a micro-jet high-pressure homogenization process, which is beneficial to maintaining the flaky structure of graphene oxide and functional fillers.

[0027] 3. During the ink film formation process, high-density flaky inorganic minerals are preferentially deposited on the whiteboard, separating the whiteboard from the black graphene oxide. The traces remain well erasable even after 30 days.

[0028] 4. During the ink film formation process, the strong interaction between the inorganic mineral flake structures, between the graphene oxide lamellae structures, and between the inorganic minerals and the graphene oxide lamellae structures quickly discharges the moisture in the ink to the surface, accelerates the curing and film formation, and achieves rapid drying of the traces. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below based on specific embodiments. The protection scope of the present invention is not limited to the following embodiments, which are listed for illustrative purposes only and do not limit the present invention in any way.

[0030] Example

[0031] The "parts" in the examples all refer to "parts by mass".

[0032] Example 1

[0033] The preparation of the whiteboard pen using water-based ink in the present embodiment comprises the following steps:

[0034] Step 1. Add 83 parts of deionized water, 2 parts of a dispersing aid (styrene-maleic anhydride copolymer), and 0.5 parts of a pH adjuster (triethanolamine) to a container equipped with a stirrer. After uniform mixing, slowly add 5 parts of graphene oxide and 5 parts of a functional filler (montmorillonite powder) while stirring. The mixture is transferred to a microfluidizer and homogenized five times at 1500 atmospheres to obtain a stable aqueous dispersion of graphene oxide and the functional filler.

[0035] Step 2. Add 3.0 parts of PVA resin to the aqueous dispersion prepared in Step 1 and stir for 2 hours. Then, add 1.0 parts of an acetylenic glycol surfactant and 0.5 parts of a fungicide, isothiazolinone, and continue stirring for 0.5 hours. The ink prepared above is filtered through a 1000-mesh filter bag to obtain a filtrate, which is the water-based ink for whiteboard markers.

[0036] Example 2

[0037] The preparation of the whiteboard pen using water-based ink in the present embodiment comprises the following steps:

[0038] Step 1. Add 78.9 parts of deionized water, 2.6 parts of styrene-maleic anhydride copolymer (a dispersing aid), and 0.7 parts of diisopropylethylamine (a pH adjuster) to a container equipped with a stirrer. After uniform mixing, slowly add 6.5 parts of graphene oxide and 6.5 parts of talc (a functional filler) while stirring. The mixture is transferred to a microfluidizer and homogenized four times at 1650 atmospheres to obtain a stable aqueous dispersion of graphene oxide and the functional filler.

[0039] Step 2. Add 3.9 parts of PVA resin to the aqueous dispersion prepared in Step 1 and stir for 2 hours. Then, add 0.7 parts of an acetylenic glycol surfactant and 0.3 parts of an isothiazolinone fungicide and continue stirring for 0.5 hours. Filter the ink prepared above through a 1000-mesh filter bag to obtain a filtrate, which is the water-based ink for whiteboard markers.

[0040] Example 3

[0041] The preparation of the whiteboard pen using water-based ink in the present embodiment comprises the following steps:

[0042] Step 1. Add 74.6 parts of deionized water, 3.2 parts of a dispersing aid (styrene-maleic anhydride copolymer), and 0.8 parts of a pH adjuster (diisopropylethylamine) to a container equipped with a stirrer. After uniform mixing, slowly add 8.0 parts of graphene oxide and 8.0 parts of a functional filler (heavy calcium carbonate) while stirring. Transfer the mixture to a microfluidizer and homogenize three times at 1800 atmospheres to obtain a stable aqueous dispersion of graphene oxide and the functional filler.

[0043] Step 2. Add 4.8 parts of PVA resin to the aqueous dispersion prepared in Step 1 and stir for 3 hours. Then, add 0.5 parts of an acetylenic glycol surfactant and 0.1 parts of a fungicide, benzisothiazolinone, and continue stirring for 0.5 hours. The ink prepared above is filtered through a 1000-mesh filter bag to obtain a filtrate, which is the water-based ink for whiteboard markers.

[0044] The weight fractions of each additive in the examples are shown in Table 1.

[0045] Table 1 Mass fractions of each auxiliary agent in Examples and Comparative Examples

[0046] additives Example 1 Example 2 Example 3 graphene oxide 5.0 6.5 8.0 Functional fillers 5.0 6.5 8.0 dispersants 2.0 2.6 3.2 Film-forming resin 3.0 3.9 4.8 surfactants 1.0 0.7 0.5 fungicides 0.5 0.3 0.1 pH adjusters 0.5 0.7 0.8 Deionized water 83.0 78.9 74.6

[0047] Comparative Example 1

[0048] Compared with Example 2, the functional filler montmorillonite powder was not added, and 6.5 parts of deionized water were added accordingly. The mass and preparation process of other additives were the same as those in Example 1.

[0049] Comparative Example 2

[0050] Compared with Example 3, 8.0 parts of heavy calcium carbonate were replaced by 8.0 parts of nano calcium carbonate. The mass and preparation process of other additives were the same as those in Example 2.

[0051] Comparative Example 3

[0052] Compared with Example 2, 6.5 parts of graphene oxide were replaced by 6.5 parts of carbon black pigment. The mass and preparation process of other additives were the same as those in Example 3.

[0053] Comparative Example 4

[0054] Compared with Example 2, the addition amounts of each auxiliary agent are the same, but the preparation process of step 1 is different.

[0055] Step 1: Prepare an aqueous dispersion of graphene oxide and functional fillers using a conventional circulating grinding process using 0.3 mm zirconium oxide beads as a grinding medium. Step 2 is the same as in Example 2.

[0056] Application performance test of water-based ink for whiteboard markers

[0057] Whiteboard markers were manufactured using commercially available fiber tips, fiber water reservoirs, and pen housing components. The drying and erasability of the traces were tested according to the product standard QB / T2859-2007, "Whiteboard Markers." The erasability over time was tested using method B, which means leaving the traces on the board at room temperature for 30 days before erasing. The test results are shown in Table 2.

[0058] Table 2 Example and Comparative Example Whiteboard pen prepared with water-based ink Whiteboard pen application performance test

[0059]

[0060] The line drying time of the whiteboard pens made of water-based ink in Examples 1 to 3 is less than 30s, which meets the requirements of the product standard. The initial erasability and the time-dependent erasability are good, and the line can be easily erased without leaving any traces.

[0061] Comparative Example 1, which also uses graphene oxide as a colorant but lacks the addition of a flaky functional filler, significantly prolonged the stitch drying time compared to Example 2. Initial erasability of the stitches was good, but after 30 days, erasability deteriorated, leaving noticeable marks.

[0062] Comparative Example 2, compared to Example 3, uses nano-calcium carbonate instead of ground calcium carbonate. Nano-calcium carbonate is a cubic calcium carbonate particle with a particle size of less than 100 nm, synthesized using a liquid-phase reaction method. The addition of nano-calcium carbonate increases the solids content of the ink, which to some extent improves drying properties. However, compared with Example 2, the drying time is still significantly longer. The initial erasability of the trace is good, but after 30 days on the board, the erasability of the trace deteriorates, leaving a noticeable mark.

[0063] Comparative Example 3, compared to Example 2, uses carbon black instead of graphene oxide. Carbon black, a black pigment commonly used in black whiteboard marker ink, is mostly granular. Compared to Example 2, the drying time of the traces is slightly increased, but the initial and time-dependent erasability of the traces are significantly lower than those of Example 2.

[0064] Comparative Example 4, compared to Example 2, employed the same additives and amounts, but differed in the process for preparing the graphene oxide and functional filler dispersions. Comparative Example 4 employed a traditional grinding process, using 0.3 mm zirconium oxide beads as the grinding medium. The high shear strength generated by the collision and extrusion of the beads fragmented the graphene oxide, and a stable dispersion was produced using the dispersant. This severe disruption of the two-dimensional structure of the graphene oxide and functional filler weakened the isolation and drainage properties of the functional filler on the whiteboard. Compared to Example 2, both line drying and erasability were poor.

[0065] Those skilled in the art should note that the embodiments described in the present invention are merely exemplary and that various other substitutions, changes, and improvements may be made within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but is only limited by the claims.

Claims

1. A water-based ink for a whiteboard marker, comprising, by mass, 5.0 to 8.0 parts of graphene oxide, 5.0 to 8.0 parts of functional fillers, 2.0 to 3.2 parts of a dispersing aid, 3.0 to 4.8 parts of a film-forming resin, 0.5 to 1.0 part of a surfactant, 0.1 to 0.5 part of a bactericide, 0.5 to 0.8 part of a pH regulator, and 73.0 to 84.0 parts of deionized water.

2. according to claim 1, whiteboard pen uses water-based ink, it is characterized in that, The functional filler is one of montmorillonite, talc and heavy calcium carbonate.

3. according to claim 1, whiteboard pen uses water-based ink, it is characterized in that, The dispersing aid is styrene maleic anhydride copolymer.

4. according to claim 1, whiteboard pen uses water-based ink, it is characterized in that, The film-forming resin is PVA resin.

5. according to claim 1, whiteboard pen uses water-based ink, it is characterized in that, The surfactant is an acetylene glycol surfactant.

6. according to claim 1, the whiteboard pen uses water-based ink, it is characterized in that, The pH regulator is an organic alkaline substance.

7. according to claim 1, the whiteboard pen uses water-based ink, it is characterized in that, The bactericide is one of isothiazolinone substances or benzisothiazolinone substances.

8. A method for preparing water-based ink for any whiteboard marker according to claim 1, characterized in that: The following steps are involved: Step 1. Deionized water, graphene oxide, functional filler, dispersing agent, and pH adjuster are added to a container equipped with a stirring device according to the formula and mixed evenly. The mixture is then transferred to a microfluidizer and homogenized 3 to 5 times at 1500 to 1800 atmospheres to obtain a stable aqueous dispersion of graphene oxide and functional filler. Step 2. Add PVA resin to the aqueous dispersion prepared in step 1, stir for 2 to 3 hours, then add surfactant and fungicide, continue stirring for 0.5 hours, and end stirring; the ink prepared above is filtered through a 1000 mesh filter bag to obtain a filtrate, which is the water-based ink for whiteboard pen.

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